Gass ,/ a&/ois Book . (i I fe & DEPARTMENT OF THE INTERIOR UNITED STATES GEOLOGICAL SURVEY GEORGE OTIS SMITH, Director Water-Supply Paper 256 GEOLOGY AND UNDERGROUND WATERS OF SOUTHERN MINNESOTA BY C. W. HALL, 0. E. MEINZER, AND M. L. FULLER WORK DONE IN COOPERATION WITH THE MINNESOTA STATE BOARD OF HEALTH WASHINGTON GOVERNMENT PRINTING OFFICE 1911 / DEPARTMENT <>K THE INTERIOR UNITED STATES GEOLOGICAL SURVEY GEORGE OTIS -Mil'll. DiBBOTOB Water -Supply Paper 256 GEOLOGY AND UNDERGROUND WATERS OF SOUTHERN MINNESOTA BY C. W. HALL, 0. E. MEINZER, and M. L. FULLER WORK DONE IN COOPERATION WITH THE MINNESOTA STATE BOARD OF HEALTH WASH ] NGTON GOVERNMENT PRINTING OFFICE 1 9 I 1 CA 4 1/ CONTENTS. Page. [ntroduction 23 Area investigated 23 Purpose and scope of the investigation L':i importance and character of the work done •_':; Available sources of water l' I Artesian prospects 25 Mineral character of the water 25 Sanitary conditions 25 Pul >1 ic supplies 25 Construction of wells 25 Bistory of the investigation 26 Physiography, by C. W. Hall ami < >. E. Meinzer 26 < reneral statement 26" < reneral contour of the upland surface 26 Minor irregularities of the upland surface 28 Features of erosion 28 Relation of drainage in upland contour 30 ( reologic history, !>><>. K. Meinzer :; I General outline 32 Pre- Paleozoic time 32 Paleozoic "periods of sedimental ion :;:; I're-( Cretaceous era of erosion 34 ( Iretaceous period of sedimentation :'."> Post-Cretaceous lime 36 Geologic formations and their water-bearing capacity, by ('. \Y. Hall 37 Surface deposits :'.7 Definition 37 Glacial drift 38 ( tut wash and terrace deposits 40 Recenl alluvium 11 Loess 41 Dune sand II Cretaceous system 42 Paleozoic rocks 42 Devonian system 42 < rrdovician system 43 Afaquoketa .-hale i I Galena limestone (3 I (ecorah -hale 1 1 Platte ville limestone 44 si. Peter sandstone M Prairie du < ihien group H5 Shakopee dolomite i"> New Richmond sandstone ' > Oneota dolomite 46 4 CONTENTS. Geologic formations and their water-bearing capacity, by C. W. Hall — Cont'd. Paleozoic rocks — Continued. Page. Cambrian system 47 Jordan sandstone 47 St. Lawrence formation 47 . Dresba'ch sandstone and underlying shales 47 Algonkian system (?) 48 Red clastic series 48 Algonkian system 49 Sioux quartzite 49 Archean system 49 Artesian conditions, by O. E. Meinzer 50 Introduction • 50 Glacial drift 50 Conditions 50 Practical applications 53 Cretaceous system 54 Paleozoic rocks 56 Sioux quartzite and glacial drift 57 Mineral quality of the underground waters, by O. E. Meinzer 57 Sources of the data 57 Interpretation of the analyses 58 Soap-consuming power 59 Formation of scale 59 Foaming 60 Corrosion 60 Surface deposits 61 Alluvium and drift waters compared , 61 Decrease in mineralization from west to east 61 Analyses considered according to provinces 63 Variations with depth 65 Chlorine content 65 Content of iron and fixed nitrogen 67 Cretaceous formations 68 Two groups of water 68 Geographic and stratigraphic relations of the two groups 71 Archean-Cretaceous contact zone 73 Paleozoic formations 74 Sioux quartzite 75 Summary 76 Problems relating to wells, by M. L. Fuller and O. E. Meinzer 78 Types of wells 78 In the surface deposits 78 In the Cretaceous 80 In the Paleozoic 81 In the Sioux quartzite 81 In the Archean 82 Finishing wells in sand 82 The problem 82 Chemistry of the incrusting process 83 Remedies 85 A well of large diameter and open eind 85 CONTENTS. 5 Problems relating to wells, by M. L. Puller and <>. K. Meinzer Continued. Finishing wells in sand -Continued. Page. A well oi huge diameter finished with a Bcreen 85 Finding a coarse layer 86 Driving the casing to the proper depth 86 Developing a natural screen 86 Making an artificial gravel screen 86 An independent pump 87 Removing the screen frequently 87 Summary 87 Drilling in quartzite 87 Phenomena due to variations in atmospheric pressure 88 Fluctuation of head 88 Variations in the yield of flowing wells 89 Roiliness of the water during Btorme 89 ' ' Blowing " and ' ' breathing " wells 90 Freezing of wells 91 Drainage by wells 92 The problem 92 Necessary conditions 92 Removal of debris and sediment from the water 93 Extent of areas that can be reclaimed 93 Hydraulic rams 94 Scientific prospecting for water 95 Public water supplies, by O. E. Meinzer 95 General statement and table 97 Cities and villages equipped with public waterworks Ill Uses of public waterworks 114 Sources of supply 116 Quantity L16 Quality. " 116 Cost '. 117 Surface sources 117 Underground sources 117 Data for southern Minnesota 119 Methods of lifting water 120 Power 121 Storage and distribution 121 Consumption of water 123 Price charged 124 The sanitary problem L26 Descriptions, by counties L28 Anoka County, by C. W. Hall and M. L. Fuller L28 Surface features L28 Surface deposits 128 Rock formations 129 Underground water conditions ISO Yield of water L30 Head of the water LSI Quality of the water LSI Summary and analyses 131 Bigstone County, by 0. E. Meinzer 132 Surface features 132 6 CONTENTS. Bigstone County — Continued. Page. Surface deposits 132 Description 132 Yield of water 133 Head of the water 1 33 Quality of the water r 133 Cretaceous system 133 Description 133 Yield of water 134 Head of the water 1 34 Quality of the water 134 Archean rocks 1 34 . Water supplies for cities and villages 135 Ortonville 135 Graceville 135 Beardsley 135 Clinton 135 Farm water supplies 136 Summary and analyses 136 Blue Earth County, by C. W. Hall and M. L. Fuller 138 Surface features 138 Surface deposits 138 Cretaceous deposits (?) 139 Paleozoic formations 139 Well records '. 140 Flowing wells 141 Water supplies for cities and villages 141 Mankato 141 Lake Crystal 142 Mapleton 142 Good Thunder 142 Amboy 142 Vernon Center 142 Summary and analyses 142 Brown County, by O. E. Meinzer 143 Surface f eatures 143 Surface deposits 144 Description 144 Yield, head, and quality of the water 144 Cretaceous deposits 144 Description 144 Yield of water 145 Head of the water 145 Quality of the water 145 Paleozoic formations 145 Sioux quartzite 146 Archean rocks 146 Water supplies for cities and villages 146 New Ulm 146 Sleepy Eye 147 Springfield .... 147 Comf rev. ..„._.„..., 147 COX IK. \ I 3. 7 Brown I tounty — Continued. Farm wain- Buppliea 117 Summary and analyses L48 Carver County, by C. W. Hall and M. L. Fuller 1 19 Surface features L49 Surface deposits 149 Rock formations 149 Eead of the water -. . . L50 Table of analyses r. I Chippewa County, by 0. E. Meinzer L51 Surface features L51 Surface deposits 152 I '.-'lip! inn 152 5field of water L52 Eead of the water L52 Quality of the water 152 Cretaceous deposits 152 Archean rocks L53 Water supplies for cities and villages L53 Montevideo L53 Milan 1 -~»:i Maynard : L54 Farm water supplies 154 Summary and analyses 154 Cottonwood County, by 0. E. Meinzer L55 Surface features 1 55 Surface d< posits .' 155 Description L55 Yield of water L56 Eead of the water 156 Quality of the water L56 Cretaceous system 156 Description L56 yield of water 157 Eead of the water r>7 Quality of the water I">7 Sioux quartzite 158 Description L58 Yield of water L58 Quality of the water L59 Water supplies for cities and villages L59 Windom L59 Mountain Lake 159 Westbrook L60 Farm water supplies 160 Summary and analyses L6] Dakota County, by C W. Hall and M. L. Fuller 162 Surface features 162 Surface deposits 163 Rock formations 164 Well records [66 Water sup] i lie- for cities and villages L67 Hastings 167 8 CONTENTS. Dakota County— Continued. Page. Water supplies for cities and villages — Continued. South St. Paul ._ 167 Mendota 168 Summary and analyses 168 Dodge County, by C. W. Hall and M. L. Fuller 169 Surface features 169 Surface deposits 170 Paleozoic formations 170 Water supplies for cities and villages 171 Kasson 171 West Concord 171 Hayfield 172 Summary and analyses 172 Faribault County, by C. W. Hall and M. L. Fuller 173 Surface features 173 Surface deposits 173 Paleozoic formations 173 Well records 174 Underground water conditions 175 Wells 175 Hpad of the water 175 Water supplies for cities and villages 176 Blue Earth 176 Wells 176 Winnebago 177 Elmore 177 Bricelyn 177 Easton 177 Delavan 178 Kiester 178 Minnesota Lake 178 Summary and analyses 178 Fillmore County, by C. W. Hall and M. L. Fuller 179 Surface features 179 Surface deposits 179 Paleozoic formations 180 Underground water conditions 181 Head of the water 181 Quality of the water 182 Wells : 182 Springs ■ 182 Water supplies for cities and villages 182 Lanesboro 182 Spring Valley 183 Preston 183 Rushford 183 Chatfield 183 Harmony 183 Wykoff 183 Fountain 184 Mabel '... 184 Canton 184 Summary and analyses 185 CONTENTS. 9 Paga Freeborn County, by C. W. Hall and M. L. Fuller L86 Surface features 186 Surface deposits 186 Cretaceous deposits (?) 186 Paleozoic formations 187 Underground water condit ions 188 Wells 188 Plowing areas 188 Springs 188 Water supplies for cities and villages 189 Albert Lea 189 Alden 189 Hartland 189 Emmons 189 Summary and analyses 189 Goodhue County, by C. \Y. Hall and M. L. Fuller 190 Surface features 190 Surface deposits 190 Rock formations 191 Underground water conditions 193 Head of the water 193 Quality of the water 193 Springs 1 93 Water supplies for cities and villages 194 Red Wing 194 ( 'annon Falls 196 Kenyon 196 Zumbrota 196 Pine Island 196 Goodhue 190 Summary and analyses 196 Hennepin County, by C. W. Hall 198 Surface features 198 Surface deposits -. 198 Rock formations 199 Sources of water 201 Lakes 201 Streams 201 Springs 201 The glacial drift 202 The sandstones 202 Head of the water 202 Quality of the water 202 Minneapolis public BUpply 203 Houston County, by C. W. Hall and M. I.. Puller 204 Surface features 204 Surface deposits 204 Hoik format ions 206 Underground water conditions 207 Sead Of tin- water 207 Quality of the water 207 Springs 208 10 CONTENTS. Houston County — Continued. Page. Water supply for cities and villages 208 Caledonia 208 Houston 209 Spring Grove 209 Hokah 209 Summary and analyses 209 Jackson County, by O. E. Meinzer 210 Surface features 210 Surface deposits - 211 Description 211 Yield of water 211 Head of the water 211 Quality of the water 212 Cretaceous system 212 Description 212 Yield of water •, 212 Head of the water 212 Quality of the water 213 Paleozoic formations 213 Sioux quartzite 213 Water supplies for cities and villages 214 Jackson 214 Lakefield 214 Heron Lake 215 Alpha , 215 Farm water supplies 215 Summary and analyses 216 Kandiyohi County, by O. E. Meinzer 217 Surface features 217 Surface deposits 217 Description 217 Yield of water 218 Head of the water 218 Quality of the water 218 Cretaceous system 219 Archean rocks 219 Water supplies for cities and villages 219 Willmar 219 Atwater 220 New London 220 Farm water supplies 220 Summary and analyses 221 Lac qui Parle County, by O. E. Meinzer 221 Surface features =. 221 Surface deposits 222 Description 222 Yield, head, and quality of the water 222 Cretaceous system 223 Description 223 Yield of water 223 Head of the water 223 Quality of the water 224 C0NTE1 11 Lac qui Parle County — Continued. Archean rocks l'-I AWi 1 1 r supplies for cities and villages 225 Madison 225 I >a sm m 225 1 1< ryd 225 Bellingham 226 Farm water supplies 226 Summary 226 Leaueur County, by C. W. Ball and M. I.. Fuller 227 Surface features 228 Surface deposits 228 Paleozoic formations 228 Underground water conditions 229 Wells 229 Bead 6f the water 230 Springs 230 Wuicr supplies for cities and villages !':'.() Lesueur 230 Waterville 231 Montgomery 231 Lesueur Center 231 Elysian 231 Kilkenny LMI Summary and analyses 231 Lincoln < lounty, l>y < >. E. Meinzer 232 Surface features 232 Surface deposits 233 Description 233 Yield of water 236 Bead of the water 236 Quality of the water 236 Underlying formations 237 Description Yield, head, and quality of the water 237 Water supplies for cities and villages 237 Lake I lent ni i 237 Tyler 238 [vanhoe 238 Bendricks 238 Farm water supplies Summary and analyses 239 Lyon County, by 0. E. Meinzer 240 Surface teat ure- 240 Surface deposits 2 in Description l' lo Yield of water l' II Bead of the water 241 Quality of the water 241 Cretaceous system 24] Description 241 Yield of water 242 B< id Of the water 24 | 12 CONTENTS. Lyon County — Continued. Page. Cretaceous system — Continued. Quality of the water '. 246 Shallow zones , 247 Intermediate zones 247 Deep zones 247 Paleozoic and Algonkian rocks 248 Archean rocks 248 Water supplies for cities and villages 248 Marshall 248 Tracy 249 Minneota 249 Cottonwood 249 Balaton 250 Farm water supplies , 250 Summary and analyses 250 McLeod County, by O. E. Meinzer 252 Surface features 252 Surface deposits 252 Description 252 Yield of water 252 Head of the water 253 Quality of the water 254 Formations beneath the glacial drift .- 254 Description 254 Yield of water 255 Head of the water 255 Quality of the water 255 Water supplies for cities and villages 255 Hutchinson 255 Glencoe 256 Brownton 256 Stewart. 256 Lester Prairie 256 Silver Lake 257 Winsted - 257 Farm water supplies 257 Summary and analyses 257 Martin County, by 0. E. Meinzer 258 Surface features 258 Surface deposits 259 Description 259 Yield of water : 259 Head of the water 259 Quality of the water 261 Underlying formations 261 Description 261 Yield, head, and quality of the water 262 Water supplies for cities and villages 263 Fairmont 263 Sherburn 263 Welcome 264 Ceylon 264 Truman 264 CONTENTS. 13 Martin County — Continued. Page. Farm water supplies 264 Summary and analyses 265 Meeker County, l>y O. E. Meinzer 266 Surface features *. 266 Surface deposits 266 Description 2GG Yield of water 2GG Head of the water 266 Quality of the water 2G7 Formations beneath the glacial drift 267 Description 2G7 Yield, head, and quality of the water 2G8 Water supplies for cities and villages 268 Litchfield 2G8 Dassel 269 Eden Valley 269 Grove City 269 Farm water supplies 270 Summary 270 Mower County, by C. W. Hall and M . L. Fuller 271 Surface features 271 Surface deposits 271 Paleozoic formations 272 Underground water conditions 273 Wells 273 Head of the water 273 Water supplies for cities and villages 273 Austin 273 Adams 273 Grand Meadow 274 Le Roy 274 Rose Creek 274 Lyle 274 Summary and analyses 274 Murray < 'ounty, by O. E. Meinzer 275 Surface features 275 Surface deposits 275 Description 275 Yield of water 276 Head of the water 276 Quality of the water 277 Cretaceous system 277 Sioux quart /.it e 277 Water supplies for cities and villages ■ 278 Slayton 278 Fulda 27s Currie 27s [ona 27!) A voca 27!) I arm water BUppliefi 27!) Summary and analyses 27!) 14 CONTENTS. Page. Nicollet County, by C. W. Hall and M. L. Fuller 280 Surface features 280 Surface deposits 280 Alluvium 280 Terrace gravels 280 Glacial drift 281 Cretaceous system 281 Paleozoic formations '. 281 Well records - 282 Algonkian rocks 282 Archean rocks 283 Water supplies for cities and villages 283 St. Peter 283 Nicollet 283 Summary 283 Nobles County, by O. E. Meinzer 283 Surface features 283 Surface deposits , '. 284 Description 284 Yield of water : 284 Head of the water 284- Quality of the water 285 Cretaceous system 285 Description 285 Yield of water 287 Head of the water 287 Quality of the water 287 Sioux nuartzite 288 Water supplies for cities and villages . 288 Worthington 288 Adrian 289 Ellsworth '. 289 Wilmont 289 Farm water supplies 289 Summary and analyses 289 Olmsted County, by C. W. Hall and M. L. Fuller 290 Surface features 290 Surface deposits. .-.' 291 Faleozoic formations 291 Underground water conditions 293 Wells 293 Head of the water 293 Water supplies for cities and villages 293 Rochester 293 Stewartville 293 Eyota 293 Summary and analyses 294 Pipestone County, by O. E. Meinzer 294 Surface features 294 Surface deposits 295 Description 295 Yield of water 295 Head of the water 295 Quality of the water 295 CONTENTS. 15 Pipestone County— Continued. Cretaceous system 295 Sinux. quartzite 295 Description 295 Yield of water 296 Bead of the water Quality of the water 297 Water supplies for cities and villages 297 Pipestone 297 Jasper 298 srton 298 Ruthton 298 Farm water supplies 299 Summary and analyses 299 Ramsey County, by C. W. Ball and M. I.. Fuller 300 Surface features 300 Surface deposits 301 Paleozoic formations 302 Underground water condil ions 303 Bead of the water 303 Quality of the water 303 St. Paul public Bupply 304 Summary 304 Redwood < iounty, by < ». E. Meinzer *304 Surface features 304 Surface deposits 305 Description 305 Yield of water 305 Bead of the water 305 Quality of the water 306 Cretaceous system 306 I >e& -i-i | • t ion 306 Yield of water 307 Bead of the water 307 Quality of the water 308 Sioux quartzite 308 A rein -a n rocks 30S Archean proper 308 White clay 309 Water supplies for cil ies and villages 311 Redwood Falls 311 Lamberton 311 Walnut Grove 3li* Sanborn ••!- Farm water supplies 312 Su miliary and analyses 313 Renville County, l>y < >. E. Meinzer 31 i Surface features 314 Surface deposits 314 Description 314 Yield of water 314 Bead of the water 315 Quality of the water 315 16 CONTENTS. Renville County — Continued. Page. Cretaceous and Archean formations 316 Description 316 Yield of water 319 Quality of the water 319 Water supplies for cities and villages 319 Renville 319 Olivia 320 Bird Island 320 Fairfax 321 Hector 321 Morton 322 Sacred Heart 322 Franklin 322 Buffalo Lake 322 Farm water supplies : 323 Summary and analyses 323 Rice County, by C. W. Hall and M. L. Fuller 324 Surface features 324 Surface deposits 325 Paleozoic formations 326 Underground water conditions 327 Wells 327 Head of the water 327 Water supplies for cities and villages 327 Faribault 327 Northfield 328 Lonsdale 329 Summary and analyses 329 Rock County, by O. E. Meinzer 330 Surface features 330 Surface deposits 330 Description 330 Yield of water 330 Head of the water 331 Quality of the water 331 Cretaceous system 331 Sioux quartzite 332 Description 332 Yield of water 333 Head of the water 333 Quality of the water 333 Water supplies for cities and villages 334 Luverne 334 Hardwick 334 Farm water supplies 334 Summary and analyses 335 Scott County, by C. W. Hall and M. L. Fuller 336 Surface features 336 Surface deposits 337 Paleozoic formations 337 Underground water conditions 339 Wells 339 Head of the water 340 Springs 340 CONTEN CS. 17 Scott County — Continued. Page. Water supplies for cities and villages 340 New Prague 340 Belle Plaine 340 Shakopee 340 Jordan 340 Merriam Junction 3 II .Summary and analyses :; 1 1 Sibley County, by C. W. Hall and M. I.. Fuller :;il Surface features 341 Surface deposits 342 Rock formations 343 Underground water conditions 345 Yield of water 345 Head of the water 345 Water supplies for cities and villages 345 Winthrop 345 Henderson 345 Gibbon 345 Summary 34(i Steele County, by C. W. Hall and M. 1.. Fuller 346 Surface features 346 Surface deposits 346 Paleozoic formations 347 Underground water conditions 348 Wells :; IS Bead of the water 348 Water supplies for cities and villages 348 Owatonna :'. IS Blooming Trairie 349 Ellendale _. 349 Summary and analyses 349 Swift County, by < ). E. Meinzer 350 Surface features 350 Surface deposits 350 Description 350 Yield of water :',.">0 Head of the water 351 Quality of the water 351 ( Iretaceous system 351 Description 35 1 Yield of water 352 Quality of the water 352 An hea ii rocks Water supplies for cil iee and \ illages Fen -oi i Appleton 353 Farm water supplies Summary and analyses :'"">i Wabasha County, by C. W. Hall and M. L. Fuller Surface features... Surface deposits 60920°— whp 256—11 2 18 CONTENTS. Wabasha County — Continued. Page. Rock formations 356 Underground water conditions 358 Wells 358 Head of the water 358 Springs 358 Quality of the water 359 Water supplies for cities and villages r 359 Wabasha 359 Lake City . 359 Plainview 359 Elgin 359 Mazeppa 359 Waseca County, by C. W. Hall and M. L. Fuller 360 Surface features 360 Surface deposits 360 Paleozoic formations 361 Underground water conditions 362 Wells 362 Head of the water 362 Quality of the water 362 Water supplies for cities and villages 362 Waseca 362 New Richland 362 Summary and analyses 362 Washington County, by C. W. Hall and M. L. Fuller 363 Surface features 363 Surface deposits 364 Rock formations 364 Underground water conditions. 366 Head of the water 366 Springs 367 Water supply at Stillwater 367 Summary and analyses 367 Watonwan County, by 0. E. Meinzer 368 Surface features 368 Surface deposits 368 Description 368 Yield of water 368 Head of the water 369 Quality of the water 369 Underlying formations 369 Description '. 369 Yield of water 370 Head of the water 371 Quality of the water 371 Water supplies for cities and villages 371 St. James 371 Madelia 372 Farm water supplies 372 Summary and analyses 372 CONTENTS. 19 Winona County, by C. W. Hall and M. L. Fuller 374 Surface features 374 Surface deposits 374 Bock formations 375 Underground water conditions 377 Head of the water 377 Quality of the water 377 Springs .- 377 Water supplies for cities and villages 377 Winona 377 St. Charles 378 Lewiston and Utica 378 Rolling Stone 378 Summary and analyses 378 Wright County, by 0. E. Meinzer r 380 Surface features 380 Surface deposits 380 Description 380 Yield of water 380 Head of the water 381 Quality of the water 381 Cretaceous rocks (?) * 381 Paleozoic and older formations 382 Description 382 Yield of water 383 Head of the water 383 Quality of the water 384 Water supplies for cities and villages 384 Buffalo 384 Delano 384 Monticello 384 Howard Lake 385 Cokato • 385 Waverly 386 Farm water supplies 386 Summary and analyses 386 Yellow Medicine County, by O. E. Meinzer 387 Surface features 387 Surface deposits 388 Description 388 Yield of water 388 Head of the water 388 Quality of the water 389 Cretaceous system 389 Description 389 Yield of water 389 Head of the water 389 Quality of the water 389 Archean rocks 390 Description 390 Yield of water. -. 390 20 CONTENTS. Yellow Medicine County — Continued. Page. Water supplies for cities and villages -. 391 Granite Falls 391 Canby .- 391 Clarkfield 391 Echo 392 Wood Lake 392 Hanley Falls 392 Farm water supplies 392 Summary and analyses 393 Index 395 ILLUSTRATIONS. / Page. Plate I. Topographic map of southern Minnesota In pocket. Hi Map showing thickness of surface deposits in southern Min- / nesota In pocket. III. Map showing occurrence of granitic rocks and Sioux quartzite in southwestern Minnesota In pocket. IV.' Map showing underground water conditions in southern / Minnesota In pocket. V. Section sheet showing geologic structure and quality of under- / ground water in southern Minnesota 34 VI. /General geologic section of southern Minnesota 36 VI I ^Geologic sections in northern Bigstone County 134 VIII: Geologic sections in Brown County 144 IX/Geologic sections in southern Cottonwood and northern Jackson / counties 156 X. Analyses of Minneapolis waters arranged and averaged according to / rock formations 202 XI. Geologic sections in Lac qui Parle County 222 XI I. ^Geologic sections in Lyon and western Yellow Medicine counties.. 244 XIII. Geologic sections in southern Murray and northern Nobles counties. . 276 XIV." Analyses of St. Paul waters arranged and averaged according to rock / formations 304 XV. Geologic sections in Renville County 320 XVI. Geologic sections in Watonwan and southeastern Brown counties.. 370 XVI I ! Geologic sections at Elk River 384 XVIII." Geologic sections in eastern Yellow Medicine County 390 Figure 1. Map showing area included in the report, and location of sections given in Plate V 24 2. Diagrammatic section across southern Minnesota 32 3. Diagrammatic section of the Cretaceous showing (1) the conditions that limit the flowing area, and (2) the supposed relations of hard and soft waters 55 4. Ideal section showing the structure which gives rise to flowing wells near the margins of quartzite plateaus 57 5. Diagram showing the relations of hard and soft Cretaceous waters. . 71 6. Diagram showing the two most common types of deep-well pumps.. 79 7 . Diagram showing two methods of drilling ' ' tubular " wells 80 8. Diagram showing the deflection of the drill in Sioux quartzite 88 9. Diagram showing the principle of the air lift 120 21 GEOLOGY AND UNDERGROUND WATERS OF SOUTHERN MINNESOTA. By C. W. Hall, O. E. Meinzer, and M. L. Fuller. INTRODUCTION. AREA INVESTIGATED. The region described in the present report includes approximately the southern two-fifths of the State of Minnesota and has an area of 28,265 square miles (fig. 1). Aside from the area occupied by the cities of Minneapolis and St. Paul, this is essentially an agricultural region. According to the census of 1905 it is inhabited by 1,295,850 persons, of whom 519,750 live on farms, 317,100 live in villages and small cities, whose existence depends on the agriculture of the region in which they are situated, and 458,800 live in Minneapolis and St. Paul, whose commercial importance depends upon an area reaching far beyond the limits of the district considered. Though southern Minnesota has passed the pioneer stage of agricultural development, there is yet in store for it great industrial progress and an accom- panying increase in population. PURPOSE AND SCOPE OE THE INVESTIGATION. Importance and character of the work done. — Although this is a region of abundant precipitation and contains a large store of both surface and underground water, yet the economic and sanitary problems connected with its water supplies are numerous and im- portant. Their importance is great if only the present develop- ment is considered; it is vastly greater if consideration is had of the inevitable future increase of urban population and the multiplica- tion of industrial requirements. The purpose of the present investigation has been to determine to the fullest practicable extent the principal facts in regard to the underground waters — their quantity, head, mineral quality, sani- tary conditions, and their depths beneath the surface — as well as the best methods of drilling to them and finishing wells for their utilization and to consider all other questions relating to their recov- ery for human use. Furthermore, to make the investigation of the greatest practical service, the results have been applied as definitely as possible to particular localities, much emphasis having for this reason been placed on the countv reports. 23 24 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. The principal problems involved in the investigation are sum- marized below. Available sources of water. — In any given locality, what water- bearing formations occur, at what depths do they lie, and how much Figure 1. — Map showing area considered and location of sections on Plate V. will they yield ? As a result of lack of knowledge on these questions, on the one hand, communities have been content to rely on unsatis- factory supplies obtained near the surface, though better water may be had at greater depths, and, on the other hand, expensive drilling INTBODTJCTION. 25 has been continued long after the lowest water horizon has been passed. By assembling all available data obtained from outcrops and well records it has become possible in large measure to answer these ques- tions for each locality, and for places for which the data at hand are not sufficient to warrant positive statements the probabilities can at least be presented in order to give a reasonable basis for intelligent action. Artesian prospects.— A question in which nearly all communities are interested is whether flowing wells can be obtained by drilling to the deeper horizons. Much blind optimism prevails in regard to this subject. Many communities have at one time or another borne the loss of expensive drilling at places where there was no real prospect of obtaining flows, and other communities are likely to suffer in the same way unless they are properly informed. In making this investigation it has been found that the deep wells already drilled give ample data for determining definitely for most communities whether or not there is any prospect of obtaining flow- ing wells. It is by no means necessary that every village or city should drill a deep well in order to learn whether flows can be obtained. Even where there are no prospects for flowing wells, the question of head is important. If the water rises higher from the deeper than from the shallower beds, it is important that the community should know it. Mineral character of the water. — The underground waters of south- ern Minnesota differ widely in their mineral content. Even in the same locality waters obtained from different horizons may be radi- cally different. As the mineral character of any water is highly important and determines to a great extent its value for domestic and industrial uses, this subject has here been fully considered, and the results of many analyses of Minnesota waters have been pre ented. Sanitary conditions. — That there is an important relation between the character of the water supply of a community and its health is a fact now well recognized. Accordingly, in the present survey, the sanitary quality of the water supplies of nearly all the villages and cities in southern Minnesota was carefully examined. Public supplies. — The problems connected with the source, lifting, storage, and distribution of public supplies are numerous, and, because of the several variable factors involved, they are not pre- cisely the same for any two communities. Many serious mistakes are made in connection with the public supplies of villages and small cities, and it is hoped that the presentation of facts and the discus- sion of conditions in southern Minnesota will be of general value. Construction of wells. — The drillers and the people of the area in- vestigated are at present contending with a number of vexatious 26 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. problems, partly mechanical and partly geologic in character, per- tainino; to the successful construction of wells. A discussion of these problems is presented in this report. HISTORY OF THE INVESTIGATION. The underground water survey upon which this report is based has been conducted under the general supervision of Prof. C. W. Hall, of the University of Minnesota. The field work for the eastern part of the area was done in 1906 by M. L. Fuller, who was assisted by F. G. Clapp and H. S. Spaulding; that for the western part was done in 1907 by O. E. Meinzer, who was assisted by E. B. Tourtellot. The investigations in 1907 were made in cooperation with the Min- nesota state board of health, which has already rendered to the State much admirable service in connection with the sanitation of the public water supplies. In general, Professor Hall and Mr. Fuller are responsible for the maps and sections of the eastern part and Mr. Meinzer for those of the western part. The authorities for most of the well sections are given in connection with the sections, but the correlations were made by the authors unless otherwise stated. In the preparation of this report the authors are indebted to many persons for assistance, suggestions, and criticisms, but especially to Mr. H. A. Whittaker and Mr. A. W. Johnston. Mr. Whittaker has given valuable aid in connection with the presentation of anal} T ses of the waters; Mr. Johnston has done much good work on the maps and sections of the eastern area. Further acknowledgments are made in the chapters on the mineral quality of the underground water and on public water supplies. PHYSIO GRAPHY. By C. W. Hall and O. E. Meinzer. GENERAL STATEMENT. Southern Minnesota as a whole is a low plateau which, generally speaking, is just starting a new cycle of denudation. In describing the topography it will be convenient to discuss, first, the general con- tour of the upland surface; second, the minor irregularities of this surface; and, third, the erosion features of the new cycle, the dissec- tion of the plateau that has thus far been accomplished by the streams which are to-day vigorously gnawing into it at a thousand points. GENERAL CONTOUR OF THE UPLAND SURFACE. A glance at the topographic map (PI. I) will show that the plateau surface of southern Minnesota lies at two distinctly different levels. The southwestern portion, forming only a small part of the total area, stands fully 500 feet above the adjacent upland plain and the PHYSIOGKAPHY. 27 transition from the one level to the other, although gradual, is rela- tively well defined, especially toward the northwest. This higher plateau, extending from Minnesota far into the Dakotas, has long been known as the "Coteau des Prairies." The upland surface of the area, exclusive of the coteau, exhibits a few large flexures, which are extremely gentle but which influence profoundly its topography and underground water and have great significance in the interpretation of its geologic history. Its highest portion, in the southeastern part of the State, forms a flat dome culminating at an elevation of about 1,400 feet above sea level in Mower County, whence it declines very gradually in all directions. Toward the east it slopes downward to the cliffs of the Mississippi, the tops of which have' an elevation of about 1,200 feet above sea level. Toward the west it slopes to the valley of Blue Earth River, which stands about 1,100 feet above sea level, beyond which it rises gently in the direction of the coteau. Toward the north it slopes to the northeast corner of the area under consideration, where the plateau is lowest, its altitude there scarcely exceeding 900 feet. Taking a different viewpoint, it will be seen that the Minnesota Valley, from Bigstone Lake to the great bend at Mankato, occupies essentially the axis of a trough in the western portion of the plateau. That is, from the crest of the uplands bordering the valley, where the average altitude is 1,050 feet, the surface rises gently in either direc- tion, reaching an elevation of about 1,200 feet at the foot of the coteau on the one side and at the north-central margin of the area on the other. Although the average upland altitude along this stretch of the Minnesota Valley is about 1,050 feet, the axis of the trough itself slopes downward from Bigstone Lake, where it is only slightly less than 1,100 feet above sea level, to Mankato, where it is somewhat below 1,000 feet. This slope is shown by the contour lines on the topographic map, the 1,100-foot contours diverging from Bigstone Lake southeastward, and the 1,000-foot contours diverg- ing from Minnesota River to Mankato. In the same sense the valley of Blue Earth River occupies the axis of a trough between the coteau on the west and the Mower County dome on the east. This axis has a north-south trend and declines from somewhat less than 1,200 feet above sea level at the state line to less than 1,000 feet at Mankato, where it converges with the axis first described. A third trough has an axis extending from the con- vergence of the other two at Mankato to the low district comprising the northeastern part of the area. In other words, the upland surface of southern Minnesota culmi- nates in three elevated regions. The most prominent is the coteau, occupying the southwestern part of the State; a much lower one is the dome in the southeastern part; and a still lower and less 28 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. conspicuous one lies near the center of the northern boundary of the area here considered. Between these three elevations there are three troughlike depressions whose axes slope away from the highest eleva- tion in the southwest toward the lowest depression in the northeast. MINOR IRREGULARITIES OF THE UPLAND SURFACE. All but the southeastern corner and perhaps the extreme south- western corner of the region is covered with glacial drift deposited during the most recent ice invasion, and hence the upland topogra- phy is essentially that produced by glaciation. Nowhere is there a more typical example of ground moraine left in the wake of a conti- nental ice sheet than is exhibited by the extensive, slightly undulat- ing, monotonous expanses of southern Minnesota, dotted with count- less shallow lakes and ponds and covered with an interminable network of swamps. This ground moraine gives to the region its characteristic topography, but it is interrupted at intervals by belts of terminal or recessional moraine, which have a surface that is equally poorly drained but much more irregular and hummocky, and that stands conspicuously above the surrounding ground moraine (PL II). The topography includes several other groups of modifying fea- tures, among them (1) flat areas that once lay at the bottom of extensive glacial lakes; (2) sharp ridges of quartzite which, in a few localities in the southwest, project abruptly above the smooth sur- face of the drift beneath which they are nearly buried; (3) outliers of resistant, horizontally bedded limestones, forming low mounds or mesas in the southeast, where the drift is thin or absent; (4) depres- sions due to sink holes where the limestone is near the surface; (5) sand dunes; and (6) areas in the southeast quarter in which the topographic rugosities have been covered over by a smooth, thin veneer of wind-driven loess. FEATURES OF EROSION. A glance at the topographic map will give a general idea of the amount of stream erosion in this area. One deep broad gorge — the valley of Minnesota River — has been cut through the heart of the area; another much deeper gorge — the valley of Mississippi River — forms its eastern boundary. The gorge of the Minnesota is not at many places cut more than 200 feet below the upland level; the gorge of the Mississippi locally reaches a depth of 500 feet. The southeastern part of the region is much more thoroughly dis- sected than the rest, and the difference is so great that the region can be divided into two distinct physiographic provinces. The southeastern province, adjacent to the Mississippi and approxi- mately 500 feet above it, is traversed by an intricate drainage system PHYSIOGRAPHY. 29 which has cut innumerable steep, rugged valleys and ravines several hundred feet into the hard rocks, in some localities leaving only remnants of the plateau surface. Here there are no lakes or swamps, for the drainage is good. A thousand steep-graded ravines conduct rain water to the Mississippi. The erosion features are conspicuous, for the present cycle of denudation is well under way and has nearly reached the stage when the denuding processes shall have attained their maximum activity. The other province, which includes much the greater portion of the total area, has an entirely different aspect. It is, indeed, dissected by one great gorge, the Minnesota Valley, the physiographic devel- opment of which, as shown by its width and depth, is anomalous as compared with that of the region through which it passes. The mo- notony of the upland surface is also interrupted by several smaller gorgelike valleys, most conspicuous among which are those of the upper Mississippi, Blue Earth, and Des Moines. Moreover, these major valleys are joined by many rugged, canyon-like tributaries that are incised into the uplands, locally producing a surface similar to that found in the southeastern province. But this stream erosion is local and exceptional. Nearly all these tributary gorges are very short and affect the topography for only a few miles back from the major valleys. Extensive interstream areas are virtually untouched by stream action. In other words, in this province the cycle of denudation is just beginning, and the region is still in its physiographic infancy. The interstream regions, which comprise vastly the greater portion of the total area, constitute the unmodified drift plain, with its ground moraine and belts of terminal and recessional moraines. The numer- ous lakes, ponds, and swamps in this region show the lack of adequate drainage. Here and there sluggish streams meander lazily over the surface, conducting the water from one swamp to another and bringing it slowly toward some distant drainage channel. One district in this province — the slope from the coteau to the lower plain — is unique. Although the gradient of the general surface here is so slight that it is scarcely perceptible, yet it has been ample to allow the surface water to run off and erode to sufficient depths to tap the ground waters, and hence to start springs that give rise to perennial streams. The little canyons thus formed, like those tributary to the Minnesota and other major valleys, are being actively eroded headward, and are encroaching more and more on the upland surface, draining lakes and swamps and diverting the sluggish creeks which meander across the uplands. Here is a great arena of stream piracy. As the cycle advances, the lazy streams of the uplands, which are entirely consequent upon the slight original irregularities of the drift plain, will be captured at many points by the vigorous subsequent streams that are aggressively developing headward. 30 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Each of the streams that rise on the coteau and empty into Minne- sota River encounters a diversity of conditions. It runs swiftly down from the coteau, eroding actively, but as it reaches the foot of the slope its grade is abruptly lessened and it is compelled to make its way across a broad, nearly flat plain. It is in much the same situation as a mountain torrent that descends through precipitous canyons and emerges suddenly on a broad plain where its velocity is checked and it is obliged to deposit its load and build up a great alluvial fan. Where the stream coming down from the coteau reaches the foot of the slope, it is no longer able to erode, and, indeed, can hardly trans- port the sediment it accumulates in its swift course. At first it flows virtually at the general level of the plain, but gradually, as it proceeds, it cuts a shallow valley. When at last it nears its mouth, it undergoes another profound change. The Minnesota is flowing at a level 100 or 200 feet lower, to reach which the stream must descend by leaps and bounds. Hence, when the stream leaves its shallow valley it enters a rugged and often picturesque gorge, from which it emerges into the broad Minnesota Valley, where it mingles its water with that of the greater stream. These are the vicissitudes of a youthful stream — one which has not yet adjusted its gradient to the topography of the region through which it flows. The topography of the extreme southwestern part of Minnesota differs somewhat from that of any considerable adjacent part of the State, although it is similar to that of a large area in Iowa. It is not notably dissected and has only shallow valleys, but its drainage is complete, lakes and swamps being few and far between. The topographic map (PI. I) shows that lakes are present through- out most of the territor}^ described, but that they are absent (1) in the southeastern province, (2) on the slope from the coteau, and (3) in the southwestern corner. Their scarcity in Lac qui Parle County and adjacent parts is explained in the report on that county. RELATION OF DRAINAGE TO UPLAND CONTOUR. It will be instructive at this point to inquire, What would be the directions of drainage if all the valleys made by recent erosion were filled and the original plateau surface were everywhere restored ? It is evident that the southwest corner would be drained southward, that the extensive northwestern trough would drain toward and along an axis nearly corresponding to the present Minnesota River from Big Stone Lake to Mankato, that the south-central trough would in like manner drain toward and along an axis roughly corresponding to Blue Earth River, and that the water from both these troughs would drain northeastward, nearly along the line of the present Minnesota River below Mankato. In other words, the drainage of most of southern Minnesota in its general features is consequent GEOLOGIC HISTORY. 31 upon the contour of the upland surface. But in the southeast this is not true. If the upland surface were here restored no Mississippi River would flow southward, providing the outlet for the drainage of most of southern Minnesota, but, on the contrary, the surface waters would flow, in general, northward from the high ground in the southeast toward the lower region in the northeast. In going from St. Paul down the Mississippi this discordance between the direc- tion of drainage and the direction of the upland slope is apparent. At St. Paul the cliffs from the valley bottom to the upland level are only of moderate height, but they become increasingly higher down- stream, at a rate entirely out of proportion to the gradient of the stream, until they tower above the river in picturesque grandeur. Farther south, along the eastern margin of Iowa, the upland surface slopes southward and the cliffs diminish in height. The influence of the topography on the level of the ground-water table, the general underground circulation, the occurrence of springs, and the artesian pressure or conditions of the region is fully considered in this report, both in the general discussion and in the various county reports. GEOLOGIC HISTORY. By O. E. Meinzer. GENERAL OUTLINE. Five great rock divisions occur in southern Minnesota. Named in the order of their age, these are the Archean, Algonkian, Paleozoic (here including the Cambrian, Ordovician, and Devonian systems), Cretaceous, and Quaternary. Tertiary stream deposits doubtless exist in some localities, but they are so unimportant that they have not been differentiated and are here considered with the Quaternary. In the northwestern and the north-central parts of the area the Archean system, consisting of granite and allied crystallines, outcrops in a number of localities and everywhere lies within a few hundred feet of the surface, but toward the south and east it slopes downward abruptly and is found only at considerable depths (PI. III). In the southwest the Sioux quartzite, which is of Algonkian age, projects up through younger formations in four districts and appears at the surface at numerous localities (PL III). The contact between the quartzite and the granite is nowhere exposed, and has only rarely been reached in drilling. In the east and south, where the granite is far below the surface, it is overlain by a succession of indurated sandstones, shales, and limestones, aggregating many hundreds of feet in thickness, at least the upper part being of Paleozoic age. Throughout most of the western part, and probably in isolated areas of the eastern part, of southern Minnesota, Archean, Algonkian, and Paleozoic rocks are 32 UNDERGROUND WATERS OP SOUTHERN MINNESOTA. covered by Cretaceous deposits consisting of soft, plastic shales and incoherent sandstones which together attain a maximum thickness of at least 500 feet, though they are generally much thinner. Spread out over all of these formations is a mantle of glacial drift which was laid down in the Pleistocene epoch, and which, except for the alluvium recently formed in stream valleys, is the youngest deposit in the region. PRE-PALEOZOIC TIME. It is difficult to outline, even in a general way, the pre-Paleozoic history of southern Minnesota. That the Sioux quartzite originated as a deposit of sand is shown by the cross bedding and ripple marks that are still preserved. Later it became thoroughly indurated, at least in some parts; it was affected by diastrophic movements, the character and intensity of which are unknown; and through these movements it came to be subjected to erosion, which, no doubt, was long continued. The prevailing features of the now nearly buried quartzite surface seem to be elevated table-lands here and there dis- sected by canyons, and generally ending in abrupt escarpments, Feet IOOO-, LAC QUI PARLE CO RENVILLE CO~~--..^ Glencoe S. j}Paleozoic (Minneapolis) Red Wing Granlta Sea level (Paleozoic / [Paleozoic IOOO- ~'a\ >Ked series *lRed y [clastic s^P [series y^y --IOOO Horizontal scale o io 20 30 40 50 60 Miles Figure 2.— Diagrammatic section across southern Minnesota. beyond which the quartzite disappears to depths not reached even by deep wells; but just what processes produced this fossil topog- raphy is a matter of speculation. As has been indicated, in the eastern part of the area here con- sidered, the granitic surface is low and is deeply buried beneath sedimentary rocks, while in the northwest it is everywhere relatively near the present surface. When the sedimentation in the east began, the granitic surface probably had even greater relief than it has at present; the sinking of this surface in the east, which seems to have taken place since that time, probably being more than counter- balanced by the erosion that has reduced the elevation in the north- west. These relations are shown in Plates III and V, and, with less detail, in figure 2, in which the dotted line x-x' represents, in a con- servative generalization, the projection of the pre-Paleozoic granitic surface, and hence suggests the relief of that surface in the west before it was reduced by erosion. The depression formed in the east by the granitic surface is filled with indurated sediments (fig. 2). The upper strata of these sedi- GEOLOGIC HISTOEY. 33 ments outcrop and, by the fossils which they include, are known to be of Paleozoic age; the lower part consists of a great thickness of red clastic beds which are not known to come to the surface, and whose age and relations are therefore problematic. Their exact re- lations to the red Sioux quartzite, on the one hand, and to the recognized Paleozoic strata, on the other, remain undetermined. N. H. Winchell and Warren Upham, the former then state geologist, believed that the Sioux quartzite, the Keweenawan series of the Lake Superior region, and the red clastic beds encountered below the recog- nized Paleozoic strata in deep drilling in southeastern Minnesota are all Paleozoic (equivalent to the Potsdam of New York); that the red clastic beds are younger than the Keweenawan series; and that they lie conformably below the recognized Paleozoic sediments. Their view as to the age of these rock series has never been generally accepted and appears to have all the probabilities against it. Recently C. W. Hall has restudied the red clastic series. He has indicated his disbe- lief in the assumption that it is closely related to the Sioux quartzite, and has shown that its lithologic character, stratigraphic situation, and geographic relations suggest that it is the sedimentary extension of the Keweenawan rocks of the Lake Superior basin, and may represent a transition from Proterozoic to Paleozoic time. 6 In this paper it is tentatively called Algonkian ( ?). PALEOZOIC PERIODS OF SEDIMENTATION. During much of the first part of the Paleozoic era the sea extended into the southern and eastern part of the area, but there is no evi- dence that at any time it covered the northwestern part. In order to understand the physical history of this period it is necessary to revert to the subject of the contour of the granitic surface. In the northwestern and north-central parts of the area this surface is every- where within a few hundred feet of the present surface ; in the eastern and southern parts it lies very much lower; and the transition from the higher level of the northwest to the lower levels of the southeast is strikingly abrupt (Pis. Ill and V and fig. 2). It is as if the ele- vations of an irregular surface of great relief were beveled off to a certain level, and the most rational explanation seems to be that such a beveling has in fact taken place. At the beginning of the Paleozoic there was probably a high granitic area in the northwest. As the era progressed this elevated district was worn down and furnished sediments which were deposited in the southeastern depressions and regions beyond, into which the sea had come, the base a Final Rept. Geol. and Nat. Hist. Survey Minnesota, vol, 1, 1882, pp. 422, 424, and 537. 6 Unpublished manuscript. 60920°— wsp 256—11—3 34 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. level to which the denudation was carried varying more or less, of course, with the oscillations of the sea. At first, when the land was high and erosion was rapid, the sediments were all clastic, and a portion of them were gravelly; later, when the land had been re- duced to a lower relief, there were long epochs in which only small quantities of fine sediments were borne seaward, and in the clear waters, teeming with lime-secreting animals, were formed thick beds of limestone. At last the submerged depressions became nearly filled with sediments and only a slight change in the level of the sea was necessary to drain the southeastern area. The Paleozoic rock succession of southern Minnesota contains one prominent unconformity, with others, no doubt, of minor impor- tance. The stratigraphic record proves that the sea extended into this area during at least the latter portion of the Cambrian period and nearly all <>1* the Ordovieian, and again during a part of the Devonian period. It further proves that the area emerged at some time during the late Ordovieian, the Silurian, or the early Devonian, for the Devonian strata rest upon an erosion surface of the Ordovieian. The Paleozoic history can therefore be summarized as follow-: A long period of submergence and sedimentation with many vicissitudes of relatively minor importance; a gradual hut probably complete emergence; a period of erosion; asecond submergence less extensive; and a complete ami final emergence, followed by a long period of erosion. PRE-CRETACEOUS ERA OF EROSION. The era <>f erosion which followed t he I Devonian sedimentation must have been long. From all indications it continued without interrup- tion during the latter part of the Paleozoic and throughout all of the Triassic, Jurassic, and early Cretaceous periods of the Mesozoic. Not until the middle or late Cretaceous did the sea again invade the region. During all this time none hut the most gentle diastrophic movements took place, ami it i- improbable that the region was ever lifted to any great height ahove the sea or had any pronounced relief. In the area in which the Cretaceous sediments rest upon the Archean, the upper part of the latter i- almost everywhere thoroughly decomposed to ; , considerable depth. The granitic residuum and the deposits immediately derived therefrom ate described at some length in the report- on Redwood and Renville counties, and it i< only neces- sary to peruse the reports «, n the various counties in which the Cretaceous rests on the Archean in order to understand how wide- spread and profound was the decomposition of the Archean surface at the time the record was sealed. This condition can not be without significance. It musl mean that the region was low and that the SHOWING GEOLOGIC STRUCTURE AND QUALITY OF UNDERGROUND WATER IN SOUTHERN MINNE GEOLOGIC HISTOEY. 35 erosive agents had become inoperative in removing the products of weathering, which were consequent^ allowed to accumulate to great depths. Another significant fact shown by the numerous sections given in this report and by all other available data is that the sediments which comprise the Cretaceous system, even in its basal members, consist almost exclusively of impalpable clay and of quartz sand such as would result from the complete decomposition of the granite. Basal gravels would probably not be so generally wanting if the region as a whole had possessed any great relief. What was the topography when the Cretaceous sedimentation began? Was southern Minnesota then a peneplain? The upland surface formed by the Paleozoic rocks of southeastern Minnesota and adjacent parts of Wisconsin and Iowa have long been regarded as an ancient peneplain (fig. 2), but, because Cretaceous sediments are not found here to any extent, it is not certainly determined whether this supposed peneplain was pre-Cretaceous or post-Cretaceous. But farther west, where Cretaceous strata rest directly upon the weathered Archean surface, the topography that existed immediately preceding the sedimentation has been preserved, except in so far as more recent deformations have produced modifications. Plates III and V show essentially what is known about this fossil topography. It is evi- dent from these plates that, while it appears nearly level when com- pared with the topography of the granitic surface preserved beneath the more ancient sediments, it has a relief of several hundred feet. Although changes of elevation have taken place since Cretaceous time, many of the irregularities are of such a character that they must have been present at the time of the Cretaceous sedimentation. If a further allowance is made for a certain amount of possible rejuve- nation of the streams concomitant with the submergence, it still remains a question how nearly the ancient surface may at one time have approximated a base level. The Sioux quartzite areas certainly rose several hundred feet above the surrounding country and formed ridges or mesas of striking prominence, comparable to the present quartzite ridges near Baraboo, Wis., while much lower and yet dis- tinct elevations also existed in the granite areas. CRETACEOUS PERIOD OF SEDIMENTATION. The Cretaceous seas encroached upon southern Minnesota from the west, and extended eastward an indefinite distance. The areas of Sioux quartzite were apparently not submerged, but were surrounded by the sea, thus forming rocky islands. A maximum of fully 500 feet of sediments were laid down, consisting chiefly of impalpable clay with some interbedded strata of sand. (See the report on Lyon 36 UNDERGROUND WATERS OE SOUTHERN MINNESOTA. County.) The submergence probably began in the Dakota epoch and ended in the Niobrara, although this is not definitely known. POST-CRETACEOUS TIME. Since the sea retreated in Cretaceous time it has not again returned, and throughout the Tertiary the entire area was once more subjected to stream erosion. Several times the Pleistocene or ''Glacial" con- tinental ice sheets invaded the region from the north, eroded the surface, and finally retreated, leaving thick deposits of glacial drift. All but the southeastern corner was at one time covered with ice, and by far the greater part was overridden by the ice of the last advance. The slight amount of postglacial stream erosion accom- plished upon the }^oungest drift sheet has been described in connection with the physiography. The uplands of southeastern Minnesota and adjacent parts seem to represent a surface which was first beveled and then gently bowed up. Mississippi River flows through this elevated area in a direction nearly opposite to the inclination of the upland surface. Such a condition could be brought about in several ways, but probably the river existed before the present elevation, and was able to cut down its valley rapidly enough to maintain its course in spite of the regional uplift. The amount of erosion effected by the Mississippi and its tributaries in this area gives a rough measure of the time that has elapsed since the uplift and present denudation cycle began. The time represented by this erosion is certainly brief when com- pared to the total time involved in the geologic history recorded in southern Minnesota; it is certainly very long when compared to the time since the youngest drift sheet was deposited. The preglacial topography of the region in the southwest known as the Coteau des- Prairies is still imperfectly understood, mainly owing to the great thickness of the drift deposits, at least in some localities. But this thickness of the drift itself proves that the present plateau-like elevation of the coteau is not entirely preglacial in origin. (See the report on Lincoln County, pp. 232-236.) Nevertheless, the high quartzite areas were there at the time of the ice invasions, and associated with them there was probably other relatively high ground; and these elevations were together competent to block the ice or divert its course to some extent. Thus in the last glacial epoch, and perhaps in a measure in earlier invasions, the ice assumed the shape of a huge tongue which was pushed across southern Minne- sota and far into Iowa, occupying the relatively low region repre- sented by the Minnesota and Blue Earth basins, and confined between the quartzite ridges and associated high land on the one side and the elevated area of southeastern Minnesota on the other. Plate II U. S. GEOLOGICAL SURVEY WATER-SUPPLY PAPER 256 PLATE VI i;, .-, Cretaceous. Algonkian (!). Formation. Columnar sectin Benton shale. Dakota sandstone. Maquoketa shale. Galena limestone. Deoorah shale. Platteville limestone. St. Peter sandstone. Prairie du Chien group: Shakopee dolomite. New Richmond sandstone. Oneota dolomite. ordan sandstone Drtslmch sandston Red elastic serie Sioux qiiartzite. m Character of strata. nsisting oi bowlder clay, sand, gravel. Approximate thickness. Yields freely in some valleys Soft blue shale and incoherent sandstone. White sandstone, etc. Limestone and sandston Shale, dolomite, and argillaceous! Limestone and shale. White or yellow sandstone, with f Yellow, bull', pink, or red dolomiti White sandstone. Buff' to reddish dolomite. Coarse-grained white sandstone. Dolomite, shale, and sandstone. Fine-grained white sandstone; shaly beds toward base. Shale, white sandstone, and thin limestone. \ Eefds small or moderate supplies l'n Yields small or moderate suppli" Locally yields moderate supplh Locally yields small supplies. Yields moderate or large supplies Yields large supplies. Locally yields small supplies. Yields moderate supplies. Generally yields moderate supplh Yields large supplies. Yields little water. Yields large supplies. Yields freely in some parts. Red sandstone and shale. Partly volcanic clastic rocks. YVhiteclay. (Decomposition |,nVm/t. In ,. : u t cuoiked and then bek.n:.'in*lM-..perl) ' » the Cretaceous D.-enn.p..sed granitic rock of red, yellow, orareea <-Olor. . gneis3, and schist. •i iclds little, water. Yields small supplies, Rarely yields small supplh Rarely yields small supplh >'.>t water bearing. GEOLOGIC SECTION OF SOUTHERN MINNESOTA. GEOLOGIC FORMATIONS. 3Y reveals a remarkable variation in the thickness of the drift, and also makes it evident that this variation has a relation to the path of ice movement. The drift is thin along the central portion of the tract followed by the ice tongue of the last invasion ; it is thick — locally very thick — along the margins of this tract as delineated by the moraines. The explanation appears to be that the ice tongue tended to erode along the central portion of its course where it was thick and the axial velocity relatively great, while it deposited its load along the margins toward which it deployed. The data at hand seem to show that the Cretaceous deposits have been removed to a greater extent along the axis of the ancient ice tongue than on either side. This may be the result of preglacial stream erosion, but it may also be due to the greater erosive activity of the ice along this line. GEOLOGIC FORMATIONS AND THEIR WATER-BEARING CAPACITY. By C. W. Hall. The five great geologic divisions recognized in this area have already been described. In the order of their age and superposition they are the Archean, Algonkian, Paleozoic (which here includes Cambrian, Ordovician, and Devonian rocks), Cretaceous, and Quater- nary (including the Pleistocene series, the Recent series, and some undifferentiated Tertiary stream deposits). (See PI. VI.) In regard to their importance in furnishing water supplies, the Pleistocene ranks first and the Paleozoic second, while the Cretaceous and Algonkian are of minor value, and the Archean is virtually destitute of available supplies, everywhere marking the lower limit of water horizons. SURFACE DEPOSITS. DEFINITION. The term "surface deposits" will be used throughout this paper to include all Pleistocene and Recent formations, together with such pre- Pleistocene materials as can not well be differentiated from them — for example, Tertiary stream deposits, which without doubt exist in some localities. In other words, it is made to include the glacial drift and all associated water and wind deposits, as well as the allu- vium laid down in the valleys outside of the drift-covered area. Such a terni is . «en to numerous criticisms, but is here employed because of its great convenience in describing underground water supplies. In discussing the surface deposits the following convenient but rather arbitrary subdivisions are recognized: (1) Glacial drift, (2) outwash and terrace deposits, (3) recent alluvium, (4) loess, and (5) dune sands. 38 UNDERGROUND WATERS OP SOUTHERN MINNESOTA. GLACIAL DRIFT. The bulk of the glacial drift consists of a matrix of clay in which are imbedded, in the most promiscuous manner, pebbles and bowlders of various sizes and composition, the whole forming an impervious mass known' as bowlder clay or till. This material was deposited by the various ice sheets which invaded southern Minnesota in the Pleistocene epoch. It was laid down either at the base of the ice as ground moraine or at the margin of the ever-melting ice sheet as terminal or recessional moraines. Intermingled and interbedded with this impervious bowlder clay, in the most intricate, chaotic, and varied maimer, and also frequently lying beneath it or above it, there are beds of porous, water-laid sands and gravels which consti- tute the water-bearing members of the drift. In some places these sand and gravel beds lie between two till sheets of distinctly different age, and represent an interglacial epoch, but the majority of them probably have not this significance. Inspection of the numerous sections of the drift given in this report makes it evident that, although a very large percentage of its material consists of impervious bowlder clay, the interbedded layers of sand and gravel are present in nearly every locality, and are nearly always encountered by wells penetrating the drift to any considerable depth. By comparing the well sections of the same locality, it also becomes evident that most of these porous beds vary widely in thickness, in coarseness of mate- rial, and in the depth at which they lie. Only rarely can a bed be traced definitely by means of well sections for more than a few miles. In the terminal and recessional moraines the percentage of sand and gravel is much higher than in the more general ground moraine. In general the drift has a dark color due to the unoxidized condition of the iron which it contains, but at the surface there is a nearly con- tinuous mantle of yellow, partly oxidized drift, varying in thickness but averaging perhaps not over 15 feet and nowhere attaining any great depth. The water in the drift is almost universally charged with iron in the soluble ferrous condition due to the general dearth of oxygen, but the analyses show that in the surficial yellow zone the water is comparatively free from iron, the obvious explanation being that the iron is here oxidized to the relatively insoluble ferric condition. In many of the undrained depressions peat deposits are forming at the present time from the accumulation of vegetable matter, and in these localities ferric compounds may be absent. Occasionally beds of yellow clay, as well as thin layers of soil and peat, exist between the deposits of dark "blue" clay. The gray or blue till, which constitutes the bulk of the drift of southern Minnesota, is derived in large part from the Cretaceous shales of this color. Pebbles of crumbly, gray-blue shale are fre- quently found in well drillings and surface exposures, and this shale is referred without question to the Cretaceous. In certain localities GEOLOGIC FORMATIONS. 39 in the eastern part of the State, however, deposits of red drift occur, the material evidently being derived from the red formations of the Lake Superior region. The distinction between northwestern and northeastern drift is frequently very clear and even striking, and the mineral composition of the water can, in a measure, be predicted through a knowledge of the source of the glacial drift from which it is derived. All but the southeastern portion of southern Minnesota was invaded by one or more ice sheets and (with the exception of a few small rock outcrops) is now covered with glacial drift. As has already been pointed out, the thickness of the drift varies through a wide range, and in some localities is great. The thickness of surface deposits, as shown on Plate II, is based on the large number of well sections assembled in the course of the investigation. In localities where few wells penetrate the underlying rocks and in localities where the forma- tion immediately beneath the drift is so similar in general character to the drift itself that drillers do not differentiate clearly between the two, the map is necessarily more or less inaccurate and the thickness indicated is likely to be too great. The drift lying at the surface along the eastern margin of the gla- ciated area, though probably not all of the same age, is distinctly older than the Wisconsin drift which covers most of southern Minne- sota. This difference in age is shown chiefly by the differences in the amount of weathering and erosion. In the oldest drift the calca- reous matter has been leached out completely to a depth of several feet, but in the Wisconsin drift this leaching has scarcely begun. The upper part of the oldest drift has been oxidized to a deep brown, but in the Wisconsin drift the oxidation of the surficial zone has generally gone only far enough to produce a pale bluish yellow color. The areal distribution of the Wisconsin drift and that of the older drift sheets, as well as the belts of terminal and recessional moraines, are shown in Plate II. The surficial layer of drift is generally not very compact, and hence allows a slow percolation of water, especially along the more grav- elly seams, but also to some extent through the unconsolidated clayey portions. Since the surface is usually poorly drained, this upper layer is in general saturated nearly or quite to the top, and very shallow dug or bored wells receive sufficient seepage for small supplies. However, in periods of prolonged drought the ground-water level is lowered, and these shallow wells are frequently left entirely dry. At greater depths occur the seams of sand and gravel already described, through which the water percolates more freely and in which it is under greater pressure, and hence will be supplied to wells at a much more rapid rate. Drilled wells ending in the best of these sand and gravel horizons yield supplies which are but slightly affected by drought, and which are adequate not only for farm use but for all 40 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. ordinary industrial and public purposes as well. In the various county reports and in the table of public water supplies (pp. 98-113) will be found a large amount of specific information in regard to the yield of wells ending in the drift. OUTWASH AND TERRACE DEPOSITS. Large streams overloaded with rock debris issued from the melting ice sheets of the Pleistocene epoch and flowed over the surface, depos- iting beds of gravel, sand, and clay, in part quite distinct from the drift proper. Eventually these glacial floods entered preexisting val- leys and rapidly filled them with rock debris. More recently the streams have cut into this filling, and now flow at lower levels, leaving the remnants as terraces. Outwash sands and gravels occur in many portions of southern Minnesota. Nearly the whole of Anoka County is covered by them, as well as large portions of many of the counties to the west. Ter- races are found mainly in the valleys of Mississippi River and Minne- sota River, but also occur along the smaller tributaries of these streams within the driftless area of southeastern Minnesota. Other elevated valley deposits remote from any present lines of drainage may be mentioned. Among these are the channel leading from Mendota southeastward across Dakota County to Rosemount, that from the northwestern corner of the same county to the Vermilion Valley near Farmington, and the chain of kamelike deposits in northern Kandiyohi County. The terraces along the Mississippi vary in width from a few hundred yards to over 10 miles, as in the "Prairie" south of Hastings. Along the Minnesota the most extensive terraces are found near Shakopee and Belle Plaine, and opposite St. Peter. Of these the first and second have a width of 1^ miles, while the third has a width of about 4 miles. The outwash sands and gravels, being open and porous, readily absorb the rain falling upon them. Where they are underlain by impervious clay, and where the region remains undissected by stream erosion, they are saturated nearly to the surface with water that con- tains relatively small amounts of dissolved minerals and is yielded freely to shallow dug or driven wells. In the terraces most of the water is derived directly from the rain, although some comes from the seepage out of the rocks forming the valley walls. The terrace gravels and sands are open and porous, and although they absorb water quickly, are as ready to give it up where the conditions are favorable as where they are cut by deep valleys. In the narrow terraces, and to some extent in the broader sandy ones, little water exists above the level of the bottom of the adjacent valley, although at many points some distance back from the drainage channels water is found at higher levels, owing to the GEOLOGIC FORMATIONS. 41 slope of the ground-water table. Where clayey layers are found, local water pockets may exist in depressions in the impervious bed. RECENT ALLUVIUM. This term refers to the gravel, sand, and clay deposited by the streams since the close of the Pleistocene epoch. It is present in greater or less amounts in all the valleys of southern Minnesota, but the thickest accumulations are in portions of the Mississippi and Minne- sota valleys, where it locally attains a depth of over 100 feet. The water of the alluvium is derived in part from the direct down- ward percolation of the rain falling on the flood plains, in part from seepage from the adjoining hillsides, and in part from the river in its flood stages, ^hen the water level in the stream rises faster than the ground water, the ordinary movement, which is toward the stream, is reversed and the river water penetrates the alluvium on each side. Although the alluvium is usually saturated below the level of the stream, not all of the water is available to wells. Clayey materials, although containing much water, hold it so firmly that little or none is given up, and even sands do not always yield their water freely. Hence it not infrequently happens that wells fail to secure the needed supplies. However, where gravel or coarse sand is encountered the yield is large. LOESS. This deposit, locally known as yellow loam or yellow clay, is a fine, nearly structureless silt, with practically no coarse grains of any kind. It is buff in color, and although somewhat plastic when wet is not a true clay. It is found mainly on the upland plateaus of the south- eastern counties, where it locally attains a thickness of 25 feet. If it has ever been deposited at lower levels in the valleys, the evidences of its presence have for the most part been removed by the subsequent deepening and widening of the valleys. The loess of this region appears to have been deposited originally by glacial waters in the Mississippi Valley, and later to have been taken up by the wind and distributed over the uplands. The deposits in southern Minnesota are so thin and so high above the general ground-water level of the region that most of the rain which they absorb eventually escapes into the underlying materials. Hence the loess is almost never a source of water, even to open wells, although in other States where it is thicker it is not uncommonly p, source of importance. DUNE SAND. Dunes are found at several points in southern Anoka County, where the sand derived from the outwash deposits has been blown by the wind into bare rounded hills from 10 to 20 feet high. Because of their exposed position they are of little value as a source of water. 4'2 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. CRETACEOUS SYSTEM. Cretaceous formations are present throughout most of the western half of the area, and thin scattered remnants appear to be widely distributed in much of the eastern half. But the mantle of drift is so nearly continuous and so little dissected by stream erosion that there are only a few small Cretaceous outcrops, and consequently knowledge in regard to the Cretaceous formations has been very meager until recently, when they have been penetrated by numerous deep wells. In their typical development in Bigstone County and in Lyon and adjacent counties they attain a maximum thickness, as far as known, of about 500 feet, and are composed of thick beds of plastic gray-blue shale, and thinner beds of white sand or sandstone. The shale, which is popularly known as "soapstone," contains pyri- tiferous layers or concretions, and in some parts includes numerous beautiful crystals of selenite. The sandstone beds, which form only a small portion of the total thickness, occur chiefly near the bottom and top of the series, although the Lyon County sections show a sandy horizon near the middle. While exact correlations are impos- sible, there is little question that the Cretaceous of southwestern Minnesota is continuous with that of South Dakota and western Iowa and corresponds to the Dakota, Benton, and possibly higher forma- tions. In the vicinity of New Ulm, where plant fossils referred to the Dakota have been described, the deposits have a more littoral aspect, and consist in large part of white sandstone and red clay. The sandstones are saturated with highly mineralized water under artesian pressure sufficient to bring it to the surface throughout con- siderable areas (PI. IV) . In a large portion of southwestern Minne- sota these sandstones constitute an important source of water supply. Although all the Cretaceous water is rich in certain dissolved minerals, some of it is soft, and hence much better for many purposes than the hard water from other horizons. PALEOZOIC ROCKS. Southern Minnesota contains a thick succession of Paleozoic for- mations comprising various beds of limestone, shale, and sandstones, most of which are of Cambrian or Ordovician age. Rocks of the Devonian period are but meagerly represented, and those of Silurian and Carboniferous age are not known in the area. DEVONIAN SYSTEM. The Devonian rocks occur in Mower County with extensions east into Fillmore County and west into Faribault. They are of various character. The lower portions consist of a gray, impure, somewhat granular limestone, interbedded with which are layers of shale of a GEOLOGIC FORMATIONS. 43 dirty brown color, due to weathering. Above the limestone lies a division consisting of sandy layers which locally develop into a true sandstone. The total thickness can not be definitely determined, although the well at Austin revealed a section of 5 1 feet in which there were observed no sandy layers. The beds of sandstone constitute the principal water-bearing portions of the Devonian. Toward the west these become so deeply buried that the water in them is under considerable artesian pressure. ORBOVICIAN SYSTEM. MAQUOKETA SHALE. The Maquoketa shale, like the Devonian representative in this area, is composed of a series of beds of varied character. In the main it consists of light-gray shales, but toward the base it carries more or less magnesian limestone, and the upper layers consist of argil- laceous sandstone. The succession of beds is not constant, however, but varies from place to place. Where well developed the formation has a thickness of about 100 feet. More or less water exists in the pores and lamination planes of the shales, in the solution passages or bedding planes of the limestone or dolomite, and in the clayey sand- stone at the top, but the amounts are usually small and the forma- tion does not generally afford satisfactory supplies. GALENA LIMESTONE. The Galena limestone immediately underlies the Maquoketa shale, and is succeeded downward by the Decorah shale and the Platteville (" Trenton") limestone. It is composed of several distinct members. Its highest layer in the recognized section, designated the Maclurea zone, is coarsely stratified, and in weathering passes into a coarse porous rock having almost the water-bearing qualities of a sand- stone. It is strongly stained by the alteration of its content of ferrous carbonate and pyrite into oxides of iron. Beneath this lies a stratum 20 feet thick, which is heavily bedded and in places strikingly colored by infiltration bands. It is frequently mistaken for a sandstone. On account of its characteristic fossils it is called the Lingulasma zone. Below this, constituting a heavily bedded stratum, is the Camarella zone, which is about 30 feet thick and is a somewhat carbonaceous limestone impregnated with iron pyrites and chalcopyrite. It is sharply separated from the shaly fossil-bearing layers of the under- lying Decorah shale. The well-defined bedding planes of the Galena limestone afford rather favorable conditions for the circulation of water, especially after they have been enlarged by solution, and moderate supplies are generally found by wells, except when the formation occurs on knobs and hills or near the edges of valleys where the water has an 44 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. opportunity to escape to the lower lands. The supplies are most abundant in the basal layers, in which the water is collected along the contact of the impervious Decorah shale. DECORAH SHALE. The Decorah shale is known in many localities in Fillmore and Olmsted counties, at St. Charles and Clinton Falls, near Faribault, at Elgin, Cannon Falls and southward to Kenyon, old Concord, and Mendota, in Minneapolis and St. Paul, and at other points along the Mississippi gorge. It occurs persistently beneath the Galena lime- stone just described, and in many localities where the limestone has been removed by glacial erosion or weathering la} T ers of the Decorah shale of varying thickness are found. It is reached by drilling in a considerable area of southeastern Minnesota. These shales are fissile, crumble easily, and carry few fossils. Their color is green or greenish- gray, weathering always to a dirty brown, due to the amount of iron originally present as a sulphide or carbonate. Interbedded with the shales, and in some localities constituting more than one-half of the thickness of the formation, are layers of crystalline limestone made up of fossil bryozoa, corals, crinoidal forms, and brachiopods. The characteristics of this formation are so unique that it can gener- ally be recognized in well sections. It contains little water, but serves a useful purpose, since it forms an impervious layer which holds a supply of water in the overlying formations, particularly the glacial drift and loess, where these rest upon the Decorah shale. PLATTEVILLE LIMESTONE. Lying beneath the Decorah shale is a bed of limestone from 12 to 30 feet in thickness, which is known as the Platteville or "Trenton" limestone. It is somewhat varied in lithologic character, in places being granular and even conglomeratic, while in others it is thoroughly crystalline. It is recognized in Minneapolis and St. Paul as the building-stone layer. In the southern part of the State it is more uniform from top to bottom and shows more distinctly the effects of water percolation along its joints and bedding planes. ST. PETER SANDSTONE. This formation is widely distributed and underlies the greater part of the area between Minnesota and Mississippi rivers, and much of Ramsey, Washington, Anoka, and Hennepin counties to the north. It varies from about 80 to 200 feet in thickness and consists of a fine- grained, white or yellow sandstone, with locally a bed of shale about 40 feet above the base. The greater part of the water of the St. Peter sandstone enters through its outcrop, where it lies immediately below the glacial drift, which serves as an excellent feeder. North of the Mississippi GEOLOGIC FORMATIONS. 45 and along its western margin extending through Scott, Lesueur, Waseca, Blue Earth, and Faribault counties, the formation is covered with drift. In Dakota County, however, especially in the southern part, the coating is thin, and the sandstone, except for a few feet of soil, is at the immediate surface and absorbs considerable quantities of water directly from the rainfall. In the counties along the Mis- sissippi it caps the uplands over extensive areas, except for a thin cover of loess which helps to collect the water and feed it to the sandstone. Owing to its position on the uplands throughout the southern portion of the area and to the deep channels cut into it by the Mississippi and its tributaries, its waters are here drained into the valleys, leaving the adjacent portions of the formation with only meager supplies. In the vicinity of St. Paul and Minneapolis the Mississippi cuts deeply into the St. Peter but does not penetrate the shale parting in the lower portion, and therefore the water beneath is confined and when encountered by wells will rise in large quan- tities nearly or quite to the surface. In the area between the Minne- sota and Mississippi margins the St. Peter, in common with other beds, is bent into a broad basin, the center of which is considerably depressed below the rims. In this basin, owing to the comparatively impervious overlying and underlying beds, the waters are confined under artesian pressure sufficient to lift them many feet above the level at which they are encountered, and the amount yielded is consequently large. PRAIRIE DTJ CHIEN GROUP. Shakopee dolomite. — This formation is a fine-grained, granular, yello\v, buff, pink, or reddish magnesian limestone, commonly ranging from 25 to 75 feet in thickness. In some localities the rock is oolitic and in others some quartz sand is present. It outcrops at Shakopee and elsewhere near Minnesota River and between St. Paul and Hast- ings on the Mississippi. To the south it rises to the uplands, underlies the thick drift deposits along the east side of the Minnesota, and out- crops in the bluffs and ravines adjoining the Mississippi. At Shako- pee, Inver Grove, and elsewhere a few wells end in this formation, but the supplies which it yields are very small. Most wells either stop in the overlying sandstone or penetrate a lower horizon. New Richmond sandstone. — This bed is rarely seen in outcrop and is not generally recognized by drillers in the northern counties. In the southern part of the State, however, it becomes better denned and apparently attains a thickness as great as 40 feet in some locali- ties. In exposures it is somewhat iron-stained, but drillings usually show it to be a pure white quartz sand. It is often more or less cemented by lime, which fact makes it difficult to distinguish it in wells from the limestone above and below, especially where, as at points in the north, it appears to be very thin. 46 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. The water probably enters chiefly through joints and other open- ings in the associated limestones. In the more calcareous phases it occurs in what are termed "fissures" by the drillers, but which appear to be local sandy zones from which the cement has been dis- solved, leaving layers of nearly pure sand. In some places joints and true solution openings seem to exist. In the sandy phases the water occupies the pores between the grains as in the St. Peter and other sandstones. Notwithstanding its thinness, the New Rich- mond is a very persistent water-bearing bed, being found throughout nearly the entire area, alwaj^s yielding more or less water, except where drained by adjacent valleys. In the north, where the forma- tion is especially thin, the supplies are generally small, although nearly always sufficient for domestic or farm demands. In Minne- apolis and St. Paul there are, however, many important wells receiv- ing their water from this sandstone. Oneota dolomite. — This is a buff or reddisn magnesian limestone from 75 to 175 feet or more in thickness. In texture it is sometimes granular, apparently being made up of a very fine dolomitic sand, which not infrequently shows distinct stratification and cross-bedding, but as a rule it is seen in heavy uniform layers of a thoroughly crys- talline habit. In its upper portion abound small openings and pockets from one-fourth to one-half inch or more in diameter and generally lined with crystals, giving the rock a distinctly porous character. In the southeastern counties, where the limestone is strongly developed in the bluffs of the Mississippi and its tributaries, there are extensive solution passages, some of which reach the dimensions of caves that may be penetrated for some distance. On the west the formation is seldom seen at the surface, but exists beneath the drift and outcrops in a few localities near Minnesota River. In the tract between the Minnesota and the eastern expo- sures along the Mississippi it lies beneath a thick covering of younger rocks (Pis. IV and V). In the upper and more porous portion of this formation small quantities of water are found, but the greater part is contained in the larger solution passages representing joints, bedding planes, or other lines of easy circulation, greatly enlarged by streams and sheets of percolating waters. One of these solution passages, known as Tyson's cave, about 4 miles northeast of Wykoff, is said to have an underground stream upon which a boat can penetrate for 200 feet. The flow of this stream is given as 50 cubic feet per minute. Another large stream, 1^ miles south of Lanesboro, flows 360 cubic feet per minute, and has in the past been used as a source of water power Owing to the density of the limestone, it affords little water to wells, except from the solution passages. When these are encountered they generally yield freely, but it is always uncertain when or where they will be penetrated by the drill. On the flat upland bordering GEOLOGIC FORMATIONS. 47 the Mississippi, the formation is an important source of domestic and farm supplies, except where drained by adjacent valleys, in which the numerous springs issuing from it are of considerable importance. CAMBRIAN SYSTEM. Jordan sandstone. — The Jordan sandstone is a loosely cemented, medium to coarse grained, white sandstone, becoming yellow or brown by oxidation along its outcrops and jointing planes. It ranges from less than 75 to nearly 200 feet thick and is exposed in the valleys of the Minnesota and tributary streams and in the lower part of the bluffs of the Mississippi and its branches from near Hast- ings southward to the Iowa state line. Elsewhere it is deeply buried beneath younger rocks (Pis. IV and V). Except in the areas adja- cent to its outcrops, it is saturated with water, which is under pres- sure and is yielded freely. When several wells are located close together there is a liability c^f some interference, but this is not com- monly serious. Except perhaps in Minneapolis and St. Paul, and at its outcrop areas, it is believed that the formation will yield all the supplies that it will be called upon to furnish for a long time to come. St. Lawrence formation. — This formation consists of buff magnesian limestone, alternating with layers of greenish shale, more or less sandy, and in its upper portion with beds of green sand several feet in thickness. It underlies nearly all of southeastern Minnesota, outcropping only in the Minnesota Valley west of Mankato and in that part of the Mississippi Valley near the Iowa line. Its thickness commonly ranges between 100 and 200 feet. The water of the for- mation is probably obtained almost entirely from the porous over- lying and underlying sandstones and from the glacial drift where this rests directly upon it. It is not a water-bearing formation of impor- tance, and is seldom if ever utilized, the yield being small. Its chief value lies in its function as a confining bed. Dresbach sandstone and underlying shales. — The Dresbach sand- stone underlies the St. Lawrence formation. It is seen along St. Croix River in northern Washington County and along Mississippi River in the southeastern part of the State. It also occurs in the Minnesota Valley, and has been reached by deep wells in every part of southeastern Minnesota as far west as Blue Earth and Faribault counties. It consists of an incoherent fine-grained sand of a prevail- ingly white color in its upper portion, followed downward by more compact layers with associated shaly beds. Throughout south- eastern Minnesota, wells which penetrate the formation show a thickness ranging between 50 and 100 feet at the various localities where records are preserved. The formation is an important bearer of water. The water, which comes largely from the eroded edges lying beneath the glacial drift, 48 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. is nearly everywhere under artesian pressure, and usually rises above the surface within the gorges of Mississippi and St. Croix rivers and some of their tributaries. The formation seems to consist of two or three somewhat independent water-bearing beds, which differ in their yield and in the height to which the water will rise. Beneath the Dresbach sandstone lies a series of beds having a persistently shaly habit. In some places the shale assumes a calca- reous character and carries layers of limestone several inches in thickness. More rarely pyritiferous beds occur, in which pellets and crystals of iron sulphide constitute a considerable portion of the material. Farther south these beds become less shaly and attain a thickness of several hundred feet, a large part of which consists of water-bearing sandstone. In the Minnesota Valley the beds come to the surface within a few miles of New Ulm, and their catchment basin extends beneath the drift from Brown County in a north- easterly direction to Chisago County and thence into Wisconsin. They hold much water under good artesian pressure, but are seldom penetrated in drilling because satisfactory supplies are usually obtained before they are reached. ALGONKIAN SYSTEM (?). Red clastic series. — The red clastic series, being generally deeply buried, is the least known of any rocks in the area. Nevertheless these red beds are revealed by deep drilling everywhere from the gneisses and quartzites of the southwestern counties eastward into Wisconsin and from the Iowa boundary northward beyond Still- water. They are nowhere exposed within this area, except possibly at Courtland, near New Ulm, in some coarse conglomerates lying upon the Sioux quartzite. In thickness they vary greatly, being many hundreds of feet thick at Minneapolis and Stillwater and gradually thinning out toward the south. In texture they vary from coarse conglomerate, through varying phases of sandstone, to fine shale, which usually forms the upper part. In color they also vary some- what, being much redder in the north than to the southeast. From their stratigraphic situation and relation to other rock formations it seems probable that these rocks are the sedimentary extension of the Keweenawan series of the Lake Superior basin. This opinion is strengthened by the fact that similar volcanic rocks are character- istic of the Keweenawan, and also by the fact that the diabase which in the Stillwater well is penetrated at a depth of 717 feet is pro- nounced Keweenawan. Until the age of the whole series is settled beyond question, however, the rocks will be called Algonkian (?). They carry little water, and drilling should always be discontinued when they are encountered. This fact was recognized twenty-five years ago by W. E. Swan, an experienced driller in the region. GEOLOGIC FOBMATIONS. 49 ALGONKIAN SYSTEM. Sioux quartzite. — This formation is exposed in a number of out- crops and has been encountered in many wells in southwestern Minnesota and adjacent parts of South Dakota and Iowa. Its dis- tribution in this State is shown on Plates III and IV. Although it consists essentially of thoroughly indurated red quartzite, it contains a few thin layers of pipestone and also some portions which are but slightly cemented and quite porous. A small amount of water is con- tained in the less indurated beds and in the joints which break up the rock, and in localities where there is no other available source of water the formation will yield supplies which, though not copious, are adequate for most purposes. AECHEAN SYSTEM. Rocks consisting of dark-colored hornblende or biotite schists, probably belonging to the Keewatin series, have been reached in a number of the deeper wells in the northwestern part of the district under investigation. They are presumed to be a southwestward extension of rocks which appear at the surface in eastern Minnesota along Kettle River and at different places on the north side of the Mesabi iron range. Gneisses and granite gneisses are found in more or less continuous exposures from New Ulm to Ortonville along Minnesota River, and in several outcrops upon the high prairie region to the southwest, in Brown, Lyon, and Yellow Medicine counties. They have been reached in a large number of wells on both sides of the river and no doubt underlie all the other formations. The occurrence of the Archean rocks is shown on Plate III. In most parts of southwestern Minnesota, where the Archean rocks are covered by Cretaceous deposits, they are profoundly decomposed. The decomposition product, as brought up by the drillers, usually consists of white clay at the top, succeeded downward by decom- posed granite of a red, yellow, light-gray, or greenish color. In a number of wells the white clay exceeds 50 feet in thickness, though it is generally much thinner. It is without a doubt a product of the decay of granitic rocks. In some places it contains embedded grains of quartz and is clearly residual, but in others its freedom from grit, its great thickness, or the fact that it includes interbedded layers of sand indicates that it has been transported and redeposited by water. If, as is probable, it was so redeposited when the Cre- taceous seas invaded the region,' the white clay is in part a basal Cretaceous formation. In this report it is included with the Archean except where it is evidently Cretaceous. Where the white clay or ordinary granitic residuum is encountered there is little probability of procuring water, though some successful wells stop in these materials. The solid rock is virtually destitute of available water. . 60920°— wsp 256—11 4 50 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. ARTESIAN CONDITIONS. By O. E. Meinzer. INTRODUCTION. A flowing well appeals strongly to the imagination, and hence in southern Minnesota, as in other parts of the country, there is a great tendency for the people to be too optimistic in regard to artesian prospects and too ready to involve themselves in heavy expendi- tures for drilling, with the hope of securing a flow. In nearly every village there are those who believe flowing wells could be obtained if drilling were carried deep enough, but perhaps in a majority of cases such a belief is based upon the most meager and imperfect knowledge of the conditions, and the wish alone is father to the thought. It is important that the people should understand that a flowing well is not an accident, but rather the resultant of a definite combination of structural and topographic conditions, which can to a certain extent be determined by those who have made a study of the subject. It is important for them to realize that random drilling without expert advice is a most costly and unwise method of pros- pecting for artesian water. In southern Minnesota flows are obtained from three distinct sources. These are the glacial drift and the Cretaceous and Paleo- zoic rock systems. Although the same general hydraulic principles are involved in all three, yet their structural and topographic rela- tions are so diverse that the artesian conditions are manifested some- what differently, and intelligent prospecting requires a knowledge of the peculiarities of each. These three geologic divisions are widely distributed and the water which they contain is generally under considerable pressure. Nevertheless, it is only in small districts where the conditions are peculiarly favorable that the pressure is great enough to lift the water above the surface. In other words, districts in which flows can be secured are the exception and not the rule. Out of the 28,000 square miles included in this report, the water from some formation will rise above the surface in approximately 700 square miles, or about 2\ per cent of the total area. GLACIAL DRIFT. CONDITIONS. The structure of the drift is unlike that of any other deposit, and the resulting artesian conditions are likewise peculiar. The surficial layer, consisting of clay with an admixture of gravel, is loosely aggregated and absorbs a certain amount of water, which percolates through it slowly. Since most of the drift-covered region is a gently AETESIAN CONDITIONS. 51 undulating plain with but slight relief and poor drainage, the rain which falls upon it flows off but sluggishly, and therefore has ample opportunity to penetrate the semiporous surface layer. Hence it follows that the ground-water table is normally near the surface, and in swampy districts virtually coincides with the land surface. In the higher morainic belts and in proximity to erosion channels, the depths of water are somewhat greater, but so imperfect is the porosity that the water table follows the topographic irregularities closely. The greater part of the drift at some distance below the surface layer is quite compact and appears to be entirely impervious, but there are interbedded with it coarse layers of sand and gravel which are nearly always saturated with water under artesian pressure. When a well is sunk into the drift the drill passes through relatively dry and im- pervious clay until a sand and gravel horizon is encountered. Then the confined water promptly rises through the boring, filling it to a level at which equilibrium is established. The water column in the well then balances the pressure in the water-bearing beds. If water is pumped out this balance is disturbed and a new supply at once flows into the well.- If, on the other hand, water should be poured into the tubing, the column in the well would then overbalance the artesian pressure and water would be forced out at the bottom of the tube until the normal level was again reached. The rate at which this adjustment takes place depends upon the porosity of the sand or gravel and is a measure of the rate at which water will be yielded. It follows that a crude estimate of the water that may be procured from a well is obtained by pouring water into it, and this method of testing is occasionally resorted to by drillers. On the higher belts of glacial moraine the water level in the wells may stand at considerable depths below the land surface, even though it rises above the horizon at which it is tapped, but on the ordinary drift plain it usually stands near the surface of the land, and in small tracts depressed below the general level of the plain it may flow at elevations slightly above the land surface. Never- theless, the absolute elevation of the water surface in wells is invari- ably greatest in regions of greatest elevation and is lowest in the depressed areas, even though here it is nearer the land surface or may even rise above it. It is probable that the most effective catchment areas- are the regions of high morainic belts. Because of the large percentage of porous material in these moraines their absorption of the rainfall is more complete than that of the area of true till, which in part forms the surface of the plains. The water that is absorbed by the moraines percolates slowly outward from them beneath the bowlder clay of the drift plains, thereby establishing artesian conditions. Where 52 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. these artesian conditions exist the ground moraine or till acts as a confining bed and appears to be fairly impervious. Nevertheless, there is doubtless some leakage through it, and this leakage may be one of the reasons why artesian basins within the drift are so mod- erate in extent. In this connection it is interesting to review a prin- ciple stated by Professor Chamberlin in 1885.° At points where water from the lower beds rises just to the level of the surface ground- water table the deeper water and the surficial water are in equilib- rium, and even though the bed that separates them is not entirely impervious there is no tendency for the water to pass in either direc- tion. In localities where the water from the deeper beds rises to a level below that of the surficial ground-water table the two bodies of water are not in equilibrium, and if the material separating them is at any point not entirely impervious water will pass from the surficial layer into the deeper beds. This relation is the general one throughout southern Minnesota. It exists not only in the morainic belts, but over the greater part of the plains. Where, in contrast to this condition, the waters from the deeper beds tend to rise above the level of the ground-water table, the resultant pressure is upward through the confining layer, and if the latter is not perfectly imper- vious there will be leakage out of the deeper beds, and as a conse- quence a diminution of the artesian pressure. The greater the dif- ference between the ground-water level and the level to which the artesian water rises the greater is this pressure, and the more rapidly will leakage take place. This condition is found only in limited areas within the low-lying districts, and the difference in the two levels is rarely great. It is only in exceptional situations where the ground- water table is nearly at the surface, as in specially depressed locali- ties, or where it is suddenly deflected downward, as along the margins of postglacial valleys, that the waters from the deeper beds will rise above the surface. In rare instances the drift gives rise to great pressure, but this is due to unusual features and need not be considered in discussing general conditions. Confining layers of till are not sufficiently impenetrable to pre- vent the escape of waters upward from the confined beds when the pressure is outward. Neither can they prevent the passage of water downward into these beds in localities where the balance of pressure favors movement in this direction. It is therefore proper to regard the entire region in which the water from confined beds fails to rise to the surficial ground-water level as a catchment or intake area. The material of the moraines and their relations to the flowing districts indicate that they play a most important part in supplying the deeper beds, but the remaining portions of the intake area, as just defined, probably also exert an appreciable influence. a Chamberlin, T. C, Requisite and qualifying conditions of artesian wells: Fifth Annual Report U. S. Geol. Survey, 18S5, pp. 139-140. ARTESIAN CONDITIONS. 53 In order to maintain artesian conditions it is probably not essen- tial that the confining layer should be absolutely impervious, but only that it should be less pervious than the water-bearing body below. Leakage upward and outward does not preclude the main- tenance of artesian pressure, provided the supply to the bed that acts as a reservoir be more rapid than the leakage outward from the bed. PRACTICAL APPLICATIONS. An understanding of the conditions that have been discussed should assist in judging of the prospects of securing flows in any given local- ity. If the till does not form an ideal confining stratum because leakage may take place through it, it is evident that general eleva- tion of surface will have less to do with the occurrence of flowing- well areas than local topography, because the till sheet is probably not capable of resisting high pressures and transmitting them for long distances. Hence a large area of relatively low land, even though it is probable that ground waters percolate toward it from an adja- cent area of relatively high land, is not likely to be a general flowing- well area. On the other hand, a valley or other limited local depres- sion, especially if its borders are rather abrupt, is a favorable locality for securing flowing wells, because pressures do not have to be trans- mitted great distances to such an area, and hence are not likely to be lost through leakage. If, in addition to this favorable local topo- graphic condition, the till contains an abundance of the lenticular masses of sand and gravel which form the most favorable deep-seated reservoirs for the storage of water under pressure, the combination of conditions is ideal, and exploration is likely to develop flowing wells. Illustrations of favorable topographic conditions will be found on Plate IV. It is evident that the water is likely to rise near to the surface at the foot of a relatively abrupt slope. If this slope occurs at the base of a steep morainic belt, the conditions may be regarded as exceptionally favorable. Exactly this situation gives rise to the flowing wells in the northeastern corner of Nobles County. There a high area of moraine rises toward the west, while the general surface descends gently toward the east. Into this gently sloping surface the valley of Jack Creek has been incised, and here a flow- ing-well area has been developed. Farther east the prairie, by a gentle grade, is brought to a level considerably below that of the valley of Jack Creek, but the water, nevertheless, will not rise to the prairie surface. It is probable that the pressure is dissipated by leakage before it reaches these points more distant from its source. Although postglacial valleys cut a short distance into the drift are the most favorable topographic features for the production of flows, yet if these valleys are cut through the confining beds artesian con- ditions are thereby destroyed and flows will not be secured. 54 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. A number of small tracts in which flows may be found in the drift are indicated on Plate IV. In general, no attempt has been made to show the localities that are regarded as favorable for flowing wells except where developments have proved that these conditions actually obtain. Hence there can be little doubt that water will rise above the surface in small districts not indicated upon the map. Although sufficiently complete data do not exist for an accurate estimate of the area over which flows from the drift may be secured, such crude esti- mates as are possible appear to indicate that the flowing-well areas constitute less than 1 per cent of the total drift-covered surface. CRETACEOUS SYSTEM. The Cretaceous formations present a structure and resulting arte- sian system that are in sharp contrast to those of the drift. The water-bearing members are without doubt far more continuous over wide areas and are better adapted to transmit water for long dis- tances, while the confining beds are very much more competent. The former consist of sandstone strata; the latter of a great thickness of shale which is so fine-grained and homogeneous that it is highly impermeable, so soft and plastic that all fissures are sealed even under moderate pressure, and so widespread and continuous, except near its margins, that there are few interruptions where water might escape. The Cretaceous, in its typical development, fulfills more nearly the ideal conditions than do most artesian systems. There are two areas in southern Minnesota in which this system gives rise to flows (1) in the valley occupied by Bigstone Lake and (2) along the foot of the coteau in Lyon and Redwood counties. The first is not extensive; the second covers approximately 200 square miles and contains a large number of flowing wells. The first shows no unusual features, but the second presents several problems, which will be briefly discussed. Both of the areas are shown in Plate IV, and they are described in detail in the reports on Bigstone, Lyon, and Redwood counties. In the Red River valley, directly north of the region included in this paper, flows are obtained over a wide territory. The Cretaceous formations extend from the western mountains, across the Dakotas, into Minnesota. In the high altitudes of the mountains the sandstones outcrop, thus forming ideal catchment areas. Eastward they pass beneath thick shale beds, and as they reach lower altitudes their water comes to be confined under great artesian pressure. The so-called James River valley is a broad belt in the eastern part of North and South Dakota, sufficiently depressed so that the Cretaceous water will rise far above the surface, and is an artesian basin of unusual interest, made possible only by the great ARTESIAN CONDITIONS. 55 efficiency of the shale beds in preventing leakage. The artesian supply is there being squandered on a grand scale. East of the James River valley lies the Coteau des Prairies with an elevation too high for flowing wells. There, indeed, as far as present knowledge is concerned, the entire Cretaceous system is virtually lost; but it reappears beneath a thin coating of drift under the low plain on the east side of the coteau, where it again gives rise to flows. But in one respect the artesian conditions are here essentially dif- ferent from those on the west side of the coteau, for the flowing area is only 6 or 8 miles in width, and is bounded on the east not by higher ground but by a gently descending plain. The topographic features are similar to those just described for the drift artesian area in north- eastern Nobles County. The structure is, however, believed to be entirely different. The principal sandstone strata, and with them the artesian conditions, are here terminated by the impervious Archean rocks, against which they abut (fig. 3), and in addition to this the confining beds become less perfect at the margin and a certain Sandstone -tT^^T^o-'i- Arcbean ~'~ " Figure 3.— Diagrammatic section of the Cretaceous, showing (1) the conditions that limit the flowing area and (2) the supposed relations of hard and soft waters. H, Main artesian hard-water zone; S, prin- cipal soft-water zone; hh', area in which hard water predominates; ss', area in which soft water pre- dominates. amount of leakage and consequent lowering of the head results. In the report on Lyon County are presented some of the data upon which these conclusions are based. When the first deep wells were drilled in the city of Marshall, the artesian pressure was found to be great, in some instances sufficient to lift the water 200 feet above the surface. Since that time (about 15 years) it has quite steadily diminished. (See specific data in the report on Lyon County.) Some of this decrease may be attributed to local interference, but apparently the explanation lies in part in the general lowering of the head. Although there are now many flowing wells, the total draft on the artesian beds is not large, and if this draft is the cause of the change in pressure, either the capacity of the water-bearing beds is very small or their conductivity is poor. Whatever may be the ulterior factors involved, it would certainly be prudent for the people of Lyon and Redwood counties to conserve their artesian supply more carefully in the future by preventing the waste that has heretofore been permitted. 56 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. PALEOZOIC ROCKS. The Paleozoic rocks form an artesian system which differs from each of the other two. They consist of a succession of beds of sand- stone, shale, and limestone, lying in a sort of pre-Paleozoic basin, and dipping gently from the periphery toward the interior of this basin. The sandstones form the principal water-bearing members and the shales constitute the most competent confining layers, while the limestones and overlying drift perform both functions to some extent. The alternation of relatively porous, with relatively impervious beds gives a succession of more or less independent artesian horizons, but the confining layers are far less competent than those of the Cre- taceous, and the intake areas are less definitely limited. In these respects the Paleozoic artesian system therefore stands intermediate between the other two. It is, however, in its topographic relations that the Paleozoic is most distinctive. It lies in southeastern Minnesota, and hence the surface consists essentially of a plateau dissected by deep-stream valleys, which in very large measure control the head. If the plateau were not dissected, the water from all horizons would come relatively near the surface, but would probably nowhere be lifted above it. But the deep valleys, which cut through successive formations, allow leakage from the water-bearing beds at many points, giving rise to countless springs, but destroying artesian conditions and greatly lowering the head of the water on the uplands. At the same time they locally bring the surface below the level to which the water beneath the undissected confining beds will rise, thus making possible the flowing wells obtained along the principal streams. The total area in southern Minnesota in which the water from Paleozoic formations will rise above the surface has been roughly estimated at 300 square miles. This area is outlined on the map (PI. IV). It will be seen that the flowing wells are confined to the valleys, and the general fact needs to be here emphasized that flows can not be obtained on the uplands. The relations of the head to the depth are similar to those in the drift. On the uplands the water from the shallow sources rises nearest the surface, and the head is generally progressively lower as deeper horizons are reached. On the other hand, in the valleys where artesian prospects exist there is a tendency for the pressure to increase slightly with the depth. Wherever the Paleozoic beds have been drawn upon to any large extent, the pressure, which in most places was originally not great, has gradually diminished, owing perhaps chiefly to interference and local depletion. To obtain the greatest benefit from the prevailing artesian conditions it is necessary here, as in the Cretaceous basin, to stop the waste that has hitherto been tolerated. MINERAL QUALITY. 57 SIOTTX QUARTZITE AND GLACIAL DRIFT. Small flowing areas may result where bodies of Sioux quartzite rise above the general level of a region. In such a place the catch- ment area is furnished by the quartzite ridge or plateau, and the confining bed is the impervious bowlder clay that laps up on the quartzite and extends as a continuous sheet to an altitude consid- erably higher than the surrounding surface. A part of the water that falls as rain sinks into the joints and less firmly cemented portions of the rock, through which it is transmitted to sandy beds of the drift that are in contact with the quartzite but lie below the confining layer of clay. A part of the water may also find its way to the deeper por- tions of the drift through sandy deposits between the quartzite and the bowlder clay without entering the former. Beneath the con- fining layer the water accumulates head, and on the low ground near £=C-r---- Drift Figure 4. — Ideal section showing the structure which gives rise to flowing wells near the margins of quartzite plateaus. the quartzite plateau it may be under sufficient pressure to rise to the surface when the confining layer is punctured. These relations are illustrated in figure 4. One of the most interesting flowing areas of this type is the one east of Hard wick (see the report on Rock County), but others are found in similar locations. MINERAL QUALITY OF THE UNDERGROUND WATERS. By O. E. Meinzer. SOURCES OF THE DATA. In all 484 mineral analyses of water from the various geologic formations in southern Minnesota appear in this paper, those from each county being arranged according to formations in a table at the end of the corresponding county report. In connection with the tables are given the depth and diameter and the owner and location of the well or other source from which each sample was taken, also the date, analysts, etc. Generally the date refers to the time the 58 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. sample was collected, but in some cases it is the date of the comple- tion of the analysis. The analyses were obtained from various sources: (1) For some years past Prof. C. W. Hall has collected chemical data from railway companies, water-softening companies, chemists, etc., and the analyses thus secured constitute a large proportion of those given in this report. Acknowledgment is due to the following companies and individuals for furnishing data: Chicago, Milwaukee and St. Paul Railway Company, G. N. Prentiss, chemist; Chicago and Northwest- ern Railway Company, G. M. Davidson, engineer of tests; Minneap- olis and St. Louis Railroad Company; Dearborn Drug and Chemical Works of Chicago; Dr. C. W. Drew, chemist, Minneapolis; A. D. Meeds, chemist, Minneapolis Board of Health; Prof. C. F. Sidener, University of Minnesota; Prof. E. E. Nicholson, University of Min- nesota; St. Paul Board of Water Commissioners; and others. (2) During the field work conducted by M. L. Fuller in 1906 a number of samples were collected from the southeastern part of Minnesota, some of which were analyzed by H. S. Spaulding and some by W. S. Hendrixson, Iowa College, Grinnell, Iowa. (3) In 1907 the Minne- sota State Board of Health cooperated with the United States Geo- logical Survey, and mineral analyses were made in their laboratories by their chemist, H. A. Whittaker, of 1.00 samples collected by O. E. Meinzer. Nearly all the analyses collected by Professor Hall were reported as hypothetical combinations and were given in grains per gallon. In order to have them agree in form with those made for the Survey, they were recalculated so that the amount of each element or radicle is shown, and the quantities are expressed in parts per million parts of water. All carbonates were recalculated as bicarbonates (HC0 3 ). It may be well to call attention to the circumstance that the total solids are in every case less than the sum of the constitutents given, which results from the fact that the bicarbonates, if they exist in solution, break down in whole or in part to form normal carbonates, and hence are only in part converted into solid matter. This can be made clearer by the following illustration, in which two bicarbonate radicles and an atom of calcium come out of solution: Calcium 4-Bicarbonate radicle — ^Calcium carbonate-f- Water 4-Carbon dioxide. Ca 4 2HC0 3 » CaC0 3 + H 2 + co 2 Solution — > Solid + Liquid 4- Gas Relative weights : 162 - > 100 + 18 + 44 INTERPRETATION OF THE ANALYSES. Underground water dissolves mineral substances from the rocks through which it percolates; and the different ingredients thus held ■ MINEBAL QUALITY. 59 in dilute solution produce noteworthy chemical and physical effects in industrial and domestic processes and in the human body. It is therefore of great moment to know the amounts and relative propor- tions of these ingredients. It is not feasible to discuss here this entire subject, with its numerous ramifications, but a few of the most important effects of the substances commonly found in solution will be briefly outlined. In what is said about the interpretation of the analyses, a recent article by Herman Stabler is closely followed. SOAP-CONSUMING POWER. For toilet and laundry purposes it is desirable to have water that will readily form a lather when soap is used. Calcium, magnesium, iron, and aluminum in solution have the capacity of combining with soap and thereby destroying its power to produce a lather. As iron and aluminum are usually present only in small amounts, the soap- consuming power can be judged approximately by considering merely the content of calcium and magnesium. The smaller the quantity of these two elements the better is the water for toilet and laundry purposes. It must be remembered, however, that one part of mag- nesium consumes as much soap as 1.6 parts of calcium.. Soft water is water that lathers readily, and hard water is water that has the power of consuming much soap before it will form a lather. The amount of soap necessary to produce a lather in a given quantity of water is a measure of the hardness. Boiling the water decreases its soap-consuming capacity by causing the precipitation of part of the calcium, magnesium, iron, and aluminum. FORMATION OF SCALE. When water is heated and concentrated in boilers, much of the dissolved substance is precipitated, forming scale and sludge, which diminish the heating power of the fuel and may eventually ruin the boiler. Suspended matter, silica, and compounds of calcium, mag- nesium, iron, and aluminum are scale-forming materials; and among these calcium and magnesium are usually present in much the largest quantities. Generally the calcium occurs in the scale as either car- bonate or sulphate, and the magnesium, iron, and aluminum as oxides. Since there is some uncertainty as to the compounds that will be formed, it is not possible to calculate, from a given analysis, the exact amount of scale that will be deposited, but the following for- mulas, computed by Stabler, will give approximately the amount and character of it. a The mineral analysis of water for industrial purposes and its interpretation by the engineer: Eng. News, vol. 00, 1908, p. 355. 60 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. A = 0.0246 Ca + 0.0138 Mg + 0.0107 Fe + 0.0157 A1 + 0.00833 Cm + 0.00833 Sm. B = 0.00833 SiO 2 + 0.0138 Mg+ (0.016 CI + 0.0118 3O 4 -0.0246 Na- 0.0145 K). The symbols in these formulas represent amounts as follows: In pounds per 1,000 gallons of water — A, the amount of scale; B, the amount of the hard-scale forming ingredients in the scale. In parts per million — Sm, the amount of suspended matter; Cm, the amount of colloidal matter (silica plus oxides of iron and aluminum) ; Si0 2 , silica; Fe, iron; Al, aluminum; Ca, calcium; Mg, magnesium; Na, sodium; K, potassium; S0 4 , sulphates; CI, chlorides. It is sometimes uncertain whether iron and aluminum are in solu- tion or in colloidal state, but little error will be introduced by assum- ing that Sm equals silica only. In applying the first formula to the analyses in this report, the results will not be greatly in error if only the calcium and magnesium terms are computed. Boiler scale varies in hardness with the composition of the water. The principal precipitates that make the scale hard are calcium sulphate and mag- nesium oxide. Silica also increases the hardness. The greater the value of B in comparison with the value of A, therefore, the harder will be the scale. When water is heated nearly to boiling under atmospheric pressure, as in an open feed-water heater, much of the calcium and other sub- stances that form soft scale are precipitated, but the hard-scale forming ingredients are left in solution. The result of such prelimi- nary treatment, therefore, is to reduce the total amount of scale formed in boilers, but to increase its hardness. FOAMING. Foaming in boilers is the forming of bubbles that do not readily break, and hence are liable to carry water out "with the steam, thus interfering with the proper action of the engine. Dissolved sub- stances increase the tendency to foam; but as sodium and potassium compounds are much more soluble than those of the other bases, and therefore remain in solution in the boiler water after the other bases have been precipitated, the proportion of sodium and potas- sium in solution is enormously increased. Therefore, the length of time a boiler can be used without blowing off the concentrated water can be measured by the amount of sodium and potassium in the boiler feed. The greater the amount of these two elements the greater will be the tendency for the water to foam. CORROSION. Water that will corrode iron is, of course, deleterious wherever that metal is used. Under the high temperatures in boilers the magnesium, MINERAL. QUALITY. 61 iron, and aluminum may be precipitated as hydrates and the acid radicles thus left in solution may cause corrosion. The carbonate and bicarbonate radicles to some extent counteract this tendency, while the danger of corrosion increases with the amounts of the sul- phate radicle and chlorine. SURFACE DEPOSITS. ALLUVIUM AND DRIFT WATERS COMPARED. The surface deposits vary widely in composition, porosity, etc., and there are correspondingly great differences in the chemical character of the waters. The alluvium water is generally less min- eralized than that from the glacial drift, as is shown by the following table compiled by M. L. Fuller. All the samples whose analyses appear in this table were collected in the eastern portion of the State, but similar results would be shown if waters of these two sources were compared in other parts of the area under consideration. Relative mineralization of waters from glacial drift and alluvium. [Parts per million.] Depth and formation. Num- ber of analy- ses! Cal- cium (Ca). Magne- sium (Mg). Sodium and po- tassium (Na+K). Bicar- bonate radicle (HCO s ). Sulphate radicle (SO*). Chlorine (CI). Total solids. to 25 feet: Drift 17 9 17 13 9 3 90 81 102 69 112 71 32 25 35 27 40 25 23 21 22 7 14 6 348 341 399 314 509 279 64 44 99 29 65 23 26 14 12 63 6 4 444 Alluvium 25 to 50 feet: Drift.. Alluvium 50 to 100 feet: Drift 406 500 312 514 299 It will be seen that the two groups do not differ greatly in the relative proportions of the different constituents, but for virtually each constituent and for each range of depth given, the average amount in the alluvium waters is somewhat less than that in the drift waters. This difference is especially noticeable in the deeper wells. DECREASE IN MINERALIZATION FROM WEST TO EAST. A marked difference exists between the mineralization of the waters from the surface deposits (glacial drift, alluvium, etc.) in the western and eastern parts of southern Minnesota. This is shown by the following table, in which all the analyses available were averaged for each county, except that in a few cases where the number was small several counties were taken together. A total of 229 analyses enter into the tabulation. 62 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Mineral content of waters from the glacial drift and other surface deposits in southern Minnesota, by counties, showing decrease from west to east. [Parts per million.] NORTHERNMOST TIER OF COUNTIES. Counties. Num- 1 er of analy- ses. Calcium (Ca). Magnesi- um (Mg). Sodium and po- tassium (Na+K). Bicarbon- ate radicle (HC0 3 ). Sulphate radicle (SO,). Chlorine Total (CI). solids. Bigstone Chippewa and Swift 9 9 3 4 8 16 196 135 126 100 73 53 74 113 45 49 29 29 18 28 178 80 26 18 S3 10 8 483 506 418 371 415 246 358 873 125 108 83 29 16 15 27 92 96 14 2 7 5 1,646 747 632 Meeker Wright...: 467 401 Hennepin and Anoka Ramsey and Washington. 252 345 SECOND TIER OF COUNTIES FROM THE NORTH. 4 14 18 10 257 99 96 98 108 49 38 33 83 87 48 10 496 499 516 375 541 157 52 74 212 37 16 10 1,526 706 McLeod Carver, Scott, and Dakota 522 428 THIRD TIER OF COUNTIES FROM THE NORTH. Lincoln Lyon Redwood Brown Nicollet and Lesueur. Rice Goodhue Wabasha 9 220 67 103 575 543 12 5 199 83 163 617 628 15 6 189 68 76 582 411 6 3 174 69 63 638 307 7 5 71 30 S4 368 135 6 7 106 44 24 410 44 35 2" 86 23 19 338 33 9 5 82 29 12 359 32 9 1,264 1.419 1,067 964 575 547 366 354 FOURTH TIER OF COUNTIES FROM THE NORTH. Pipestone 2 12 5 .8 3 7 9 110 203 223 167 25 67 77 53 13 77 87 60 395 452 522 559 45 523 600 291 18 23 8 4 444 1,145 1.2S0 902 Blue Earth Waseca Steele 107 98 41 34 28 59 478 486 75 105 12 8 507 659 Dodge Olmsted and Winona 64 25 7 298 27 8 298 FIFTH TIER OF COUNTIES FROM THE NORTH. Rock 2 6 7 10 4 3 4 4 2 124 221 135 156 96 122 77 SO SO 29 77 47 48 34 34 17 25 32 46 64 50 76 44 23 11 11 15 515 421 417 459 480 412 263 365 358 88 575 270 371 76 105 63 35 33 8 35 11 10 3 30 11 18 23 584 1,245 742 Martin Faribault 901 496 520 329 343 Houston •_ 370 The above table shows that in each tier of counties, from the west- ern margin of the State eastward to the Mississippi, there is a gradual but decided decrease in the total mineralization of the water from the glacial drift and other surface deposits, and that this is due to a decrease in the amounts of most of the important constituents. Thus, excluding Pipestone and Rock counties, the average content MINERAL QUALITY. 63 of calcium and magnesium is only a little over one-third as great in the eastern as in the western part, the average content of sodium and potassium is only about one-tenth as great, and in the content of sulphates the difference is still wider. The cause of this condition is not difficult to find. The glacial drift of the western counties is derived from the Cretaceous sediments which underlie the western portion of this State, as well as the region beyond, while the drift of the eastern counties was abraded chiefly from the Paleozoic formations. The marked difference between the Cretaceous and the Paleozoic rocks, in the amount of soluble matter which they contribute to the underground water, is shown later in this chapter. ANALYSES CONSIDERED ACCORDING TO PROVINCES. For the present purpose, southern Minnesota will be separated into three general provinces — southeastern, southwestern, and north- central. Although this is a somewhat arbitrary division of the region, it makes it possible to bring out important relations that can not otherwise be shown. Broadly speaking, it may be said that in the first province the glacial drift is underlain by Paleozoic formations and in the second by Cretaceous. The third, which lies entirely north of Minnesota River, is in a sense intermediate. The southeastern province includes the following counties : Anoka, Hennepin, Ramsey, Washington, Carver, Scott, Dakota, Lesueur, Rice, Goodhue, Wabasha, Blue Earth, Waseca, Steele, Dodge; Olm- sted, Winona, Faribault, Freeborn, Mower, Fillmore, and Houston. The ensuing table gives the composition of waters from different depths in the glacial drift and other surface deposits of this area. It was compiled by averaging all the available analyses within the assigned limits of depth. Mineral content of waters from different depths of glacial drift and other surface deposits of ■ the southeastern province, southern Minnesota. [Parts per million.] Depth. Num- ber of analy- ses. Calcium (Ca). Magne- sium (Mg). Sodium and po- tassium (Na+K). Bicarbo- nate radi- cle (HC0 3 ). Sulphate radicle (S0 4 ) Chlorine (CD. Total solids. to 25 feet 20 30 12 18 87 88 102 81 30 32 36 30 22 14 12 46 346 361 452 375 57 69 55 78 22 34 6 31 431 25 to 50 feet 418 50 to lOOfeet 460 Over 100 feet 463 The table shows that the waters of this group are moderately mineralized, and that the principal constituents are calcium and magnesium in equilibrium with the bicarbonate radicle, the quanti- ties of chlorine and sulphates and of sodium and potassium being comparatively small. The normal amounts of chlorine are probably 64 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. less than those in the table, because the averages are raised by includ- ing a number of samples believed to be polluted by sewage. The average water of this group consumes considerable soap, but can be appreciably softened by heating. In boilers it is not corrosive, has little tendency to foam, and forms scale that is only moderately hard. The following counties are included in the southwestern province: Bigstone, Lac qui Parle, Yellow Medicine, Lincoln, Lyon, Redwood, Brown, Pipestone, Murray, Cottonwood, Watonwan, Rock, Nobles, Jackson, and Martin. The table here given was compiled, like the previous one, by averaging all available analyses within the pre- scribed limits of depth from which the samples were taken: Mineral content of waters from different depths of glacial drift and other surface deposits of the southwestern province, southern Minnesota. [Parts per million.] Depth. Num- ber of anal} r - ses. Calcium (Ca). Magne- sium (Mg). Sodium and po- tassium (Na+K). Bicarbo- nate radi- cle (HC0 3 ). Sulphate radicle (SO,). Chlorine (CI). Total solids. to 50 feet 37 18 20 13 157 213 198 235 57 85 72 78 51 95 136 125 448 530 550 523 301 598 874 074 38 13 14 17 868 50 to 100 feet 1,293 100 to 200 feet 1,300 Over 200 feet 1,417 In this province the waters from all depths are highly mineralized, each of the common ingredients being present in quantity. Since there are large amounts of calcium and magnesium, the waters are very hard; and since the sulphate radicle is much in excess of the sodium and potassium they will form hard scale in boilers. The following counties are included in the north-central province : Swift, Kandiyohi, Meeker, Wright, Chippewa, Renville, McLeod, Sibley, and Nicollet. The next table shows the average composition of the waters from different depths in the surface deposits of this region : Mineral content of waters from different depths of glacial drift and other surface deposits of the north-central province, southern Minnesota. [Parts per million.] Depth. Num- ber of Calcium Magne- analy- ses. (Ca). (MgJ. 19 135 47 6 137 49 11 78 37 18 71 35 Sodium J Bicarbo- and po- ; nate radi- tassium I cle (Na+K). (IICOs). Sulphate radicle (SO,). Chlorine (CI). Total solids. to 50 feet... 50 to 100 feet. 100 to 200 feet Over 200 feet. 416 541 513 144 183 44 55 621 837 527 A casual comparison of the three tables makes it evident that this group is in general intermediate in composition between the first two. MINERAL QUALITY. 65 VARIATIONS WITH DEPTH. The table for the southeastern province shows no important vari- ation with depth in any of the dissolved constituents. In the tabulation for the southwestern province the waters within 50 feet of the surface are on an average somewhat less highly miner- alized than those at greater depths, there being smaller quantities of calcium, magnesium, sodium and potassium, bicarbonates, and sul- phates. Inspection of the 27 analyses of waters less than 50 feet deep shows that this difference is due chiefly to the samples derived from the alluvial and outwash sands and gravels at the surface. If only analyses from the glacial drift proper were considered, the waters from a depth of less than 50 feet would be shown to have virtually the same mineralization as those from deeper sources. With the exception just noted, the composition does not appear to vary with the depth, the differences shown in the table being small and probably accidental. Thus the average composition of the 18 samples secured from between 50 and 100 feet is essentially the same as that of the 13 samples from a depth of more than 200 feet. In the waters of the north-central province a distinct variation with depth is discernible. The samples from less than 100 feet below the surface are somewhat richer in total solids than the deeper waters, owing to their decidedly greater content of calcium and magnesium and of the sulphates. The amount of bicarbonates is practically the same for different depths, and, since the analyses which were aver- aged together differ widely in the amounts of sodium and potassium, it is probable that the variations shown in respect to these elements should be regarded as accidental. Because of the difference in the quantity of the alkaline-earth bases (calcium and magnesium), the soap-consuming power and the amount of scale deposited in boilers are greater in the shallow than in the deep waters; and because of the much larger amount of sulphates, with no corresponding differ- ences in the alkalis and bicarbonates, the soap-consuming power after heating the water is much greater, while the scale formed is much harder. The deep water is superior to the shallow for boiler, laundry, and toilet purposes. CHLORINE CONTENT. The tables show the average chlorine content to be highest in the waters near the surface, but this is believed to be due to the more frequent contamination of shallow wells. The sources of many of the samples included in the tables for the southwestern and north- central provinces were examined from a sanitary point of view, and bacteriological analyses were made of the waters. If all samples are rejected that were thrown under suspicion of pollution either by 60920°— wsp 250— IX 5 66 UNDERGROUND WATERS OE SOUTHERN MINNESOTA. inspection of the source or by the fact that they contained Bacillus coli, or both, those that remain show the following content of chlorine: Chlorine content of unpolluted waters from the glacial drift and other surface deposits. _ , . Number of Southwestern province: analyses. 1 part per million 1 2 parts per million 2 3 parts per million 4 4 parts per million 4 5 parts per million 4 6 parts per million 3 7 parts per million 4 8 parts per million 9 parts per million 2 10 parts per million Total less than 10 parts per million 24 More than 10 parts per million 3 North -central province: 1 part per million 3 2 parts per million 6 3 parts per million 2 4 parts per million 2 5 parts per million 2 6 parts per million 2 7 parts per million 1 8 parts per million 9 parts per million 1 10 parts per million 1 Total 10 parts or less per million 20 More than 10 parts per million 5 In the first group, of the three analyses with more than 10 parts per million, one represents water from the shallow open well that furnishes the public supply at Mountain Lake and shows only 11 parts; the other two represent waters from the village wells at Canby and Clinton. By referring to the proper county reports (Yellow Med- icine and Big stone), it will be seen that in both of the last-named wells the water is drawn from the base of the drift, from horizons especially close to the Cretaceous waters in the region where they contain the largest quantities of chlorine. In the second group two of the five analyses with more than 10 parts per million represent the waters from the village wells at Olivia and Renville and show, respectively, 13 and 14 parts. These are rather deep wells and extend virtually to the underlying Cretaceous or altered Archean, from which the excess of chlorine may be derived. The other three analyses represent waters from the city wells at Litchfield, a private well at Litchfield, and the village wells at Atwater and show, respectively, 17, 35, and 35 parts per million. All three are shallow wells driven into surficial deposits of sand. "While there is no indication of MINERAL QUALITY. 67 pollution, it seems possible that the extra amount of chlorine comes originally from sewage. The evidence of the reliable analyses avail- able seems to be that the waters from the glacial drift and other sur- face deposits in these two provinces tend to contain not over 10 parts per million of chlorine unless (1) they are mingled with water from another formation which bears more chlorine or (2) they receive chlorine through human agencies. However, the number of analyses is too small to allow generalization, and more extended investigation may develop different results. CONTENT OF IRON AND FIXED NITROGEN. Most of the iron in solution in the water is in the ferrous state, but whenever it comes in contact with oxygen the greater part is con- verted to the ferric state, in which condition it is so nearly insoluble that most of it is precipitated. In order to ascertain the true con- dition of the iron in the underground waters, it is therefore necessary to take the samples directly from the wells before the water has been aerated. Moreover, it must be derived from a drilled or driven well rather than from an open well of large diameter in which the water is reservoired and comes in contact with the atmosphere before it is pumped. The following table contains such samples from drilled and driven wells and springs as were collected with the precautions above prescribed, and, for purposes of comparison, the samples that were taken from open (bored and dug) wells. The table shows not only the content of iron, but also that of free ammonia and nitrates, in the same samples. Content of iron, free ammonia, and nitrates in waters from the glacial drift and other surface deposits. [Parts per million.] Nitrate radicle (NO.). Drilled and driven wells and springs Depth less than 50 feet Depth 50 to 100 feet Depth 100 to 200 feet Depth over 200 feet Bored and dug wells: Depth less than 50 feet Depth over 50 feet Driven wells— all shallow Number Total Free of iron ammonia analyses. (Fe). (NHs). 9 0.9 0.3 6 3.1 .6 7 2.5 1.4 17 2.3 1.8 17 .7 .1 5 1.6 .7 4 .1 .1 7.8 1.0 .0 .1 23.6 4.3 5.2 a Springs are included with wells less than 50 feet deep, although some of them would more properly be classified with the deep wells. The table shows that the waters from drilled and driven wells of all depths over 50 feet contain considerable iron, but those from the shallow wells contain relatively little. This condition apparently results from the fact that in the bulk of the drift the iron and other substances capable of oxidation exist in a partly reduced or deoxi- dized state (as is shown by the dark color of the clay and sand), and 68 UNDERGROUND WATERS OF SOUTHERN" MINNESOTA. the water is consequently robbed of virtually all dissolved oxygen which it may once have possessed; while, on the other hand, the deposits near the surface are generally oxidized (as is proved by their yellow color), and hence have not the power of divesting the water of its load of atmospheric oxygen. The deeper waters there- fore have abundant opportunity to take into solution iron in a soluble ferrous condition, while near the surface this element is kept in the insoluble ferric state by the excess of oxygen. The driven wells represent more strictly surficial conditions than do springs and drilled wells less than 50 feet deep, and accordingly they show a still lower content of iron. The smaller average amounts of iron in the water from the bored and dug wells of equivalent depths should probably be attributed, at least in part, to aeration of the water after the latter enters the well and before it is pumped to the surface. Analogous to ferrous and ferric iron are the two combinations in which most of the fixed nitrogen in the water is found. Where there is a deficiency of oxygen, ammonia predominates, but in waters containing an abundance of oxygen the prevailing nitrogenous com- pounds are the nitrates. This condition is shown in the above table, in which in general the ammonia varies directly and the nitrate radicle inversely with the iron. It is possible that in water contain- ing ferrous iron some of the ammonia is formed by the reduction of nitrates after the water is pumped. The large amount of nitrates in the shallow bored and dug wells is probably in part caused by the direct introduction of decomposed organic material. CRETACEOUS FORMATIONS. TWO GROUPS OF WATER. The following table includes all the available analyses of waters derived from Cretaceous formations in southern Minnesota. They are arranged according to their calcium content. Analyses of waters from Cretaceous formations in southern Minnesota. [Parts per million.] County. Lyon Watonwan. . Do Lyon Cottonwood. Lyon Cottonwood. Lyon Cottonwood. Jackson No. a Calcium (Ca). Mag- nesium (Mg). Sodium and po- tassium (Na+K). Bicar- bonate radicle (HCO,). Sulphate radicle (S0 4 ). Chlorine (CI). 11 329 97 339 676 1,279 51 9 327 118 83 512 1,026 4 10 324 116 146 503 1,121 10 14 324 99 422 387 1,679 47 9 287 99 129 713 759 19 12 261 75 203 420 934 40 7 219 75 150 539 705 6 13 209 139 415 716 1,317 30 10 159 46 348 385 971 12 8 158 57 43 459 346 3 Total solids. 2,449 1,853 1,994 2,774 1,677 1,789 1,545 2,473 1,797 845 a The numbers are those under which the analyses are given in the tables accompanying the correspond- ing county reports, MINERAL QUALITY. 69 Analyses of waters from Cretaceous formations in southern Minnesota — Continued. County. Lyon Do Do Brown Do Lyon Redwood Lyon Cottonwood Redwood Lyon Bigstone Yellow Medicine. Lyon Bigstone Do Do Do Do Do Redwood Lac qui Parle Calcium (Ca.) 139 138 130 77 71 59 57 40 37 32 31 25 23 22 18 17 17 17 17 17 17 10 Mag- nesium (Mg.) Sodium and po- tassium (Na+K). 182 214 242 163 144 524 508 269 512 457 258 951 251 536 351 321 337 341 1,021 1,029 423 248 Bicar- bonate radicle (HCOs). 231 283 296 2SS 270 325 371 268 2S3 701 242 478 229 361 527 493 566 562 400 400 263 483 Sulphate radicle (SO4). 630 645 689 223 257 950 912 291 933 450 378 .871 137 819 284 248 252 256 1,167 1,161 709 136 Chlorine (CJ). 18 39 18 131 104 49 29 92 13 40 52 535 215 63 78 65 67 68 490 505 23 27 Total solids. 1,150 1,244 1,271 789 756 1,793 1,816 854 1.710 1,339 836 2,662 759 1,663 1,044 931 977 978 2,946 2,959 1,345 697 If all the Cretaceous analyses tabulated above are divided into two arbitrary groups, those showing less than 80 parts per million of calcium and magnesium being placed in the "soft water" group, and those showing a greater content of these elements being included in the "hard water" group, the average results will be as follows: Average content of soft and hard Cretaceous waters. [Parts per million.] Group. Number of analyses. Calcium (Ca). Mag- nesium (Mg). Sodium and po- tassium (Na+K). Bicar- bonate radicle (HC0 3 ). Sulphate radicle (SO*). Chlorine (CI). Total solids. 17 15 26 210 10 74 500 215 414 445 584 837 146 35 1,486 1,625 The data thus presented bring out a number of very interesting facts. In the first place they show that the Cretaceous waters differ radically in their content of calcium and magnesium, the elements which give hardness to the waters. The range of calcium, as shown in the large table, is between 10 and 329 parts per million, and the range in magnesium between 7 and 97 parts. Although there are some analyses that show intermediate amounts of these elements, there appears to be a tendency for the Cretaceous waters to be either rather soft or very hard. It will be observed that the total amount of solids dissolved in all the Cretaceous waters is great. Of the 32 analyses given above, the range is between 697 and 2,959 parts per million, and the average is 1,560 parts. It will further be noted that the average of total solids is nearly the same for the two groups (that is, the hard and the soft), 70 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. but that the substances which make up the totals occur in very different proportions. All the Cretaceous waters are rich in the alkalies (sodium and potassium), but the soft waters are much richer than the hard, the average content in the former group being 500 parts per million, while in the latter it is only 215. It should here be explained that among the latter, No. 9 in Watonwan County and No. 8 in Jackson County, which show less sodium and potassium than the others, probably represent Cretaceous water diluted by water from the drift. All Cretaceous waters contain an abundance of sulphates, and in many the quantity is excessive; but the average amount is greater in the hard waters than in the soft, being 837 parts per million in the former and 584 in the latter. While the large table shows that there is a wide range in the sulphate content within each of the two groups, it also seems to show that the averages are not entirely accidental, but that there is a tendency for the waters with much calcium and magnesium to have especially large amounts of sulphates. Virtually all the Cretaceous waters are rich in chlorine. Only four analyses in the above tables show 10 or less parts per million, and these represent waters which, from their known geologic relations, may well be derived in part from the glacial drift. Nearly all the waters whose analyses are given above come from deep drilled wells, and in very few of them is it probable that the chlorine content has been appreciably augmented by pollution. The average chlorine for the soft waters is much greater than that for the hard, and although there are great variations in both groups it appears evident that these averages represent real tendencies. Indeed, all the distinctly saline waters are soft. The average content of combined carbonic acid (represented by the bicarbonate radicle) is only moderate, and it is nearly the same in the two groups; furthermore, the range among the individual analyses is relatively small. In general, two distinct waters of different chemical composition seem to occur; calcium, magnesium, and the sulphate radicle pre- dominate in one water over the alkalies and chlorine; sodium, potassium, and sulphates, with moderately large amounts of chlorine, predominate in the other over the alkaline-earth bases. The differ- ences are presented graphically by the continuous lines in figure 5. The first water is extremely hard and forms a great amount of hard scale in boilers; moreover it is corrosive and readily causes foaming. The second is distinctly softer and much better for laundry and toilet purposes, but it is likely to cause serious foaming, especially in loco- motive boilers. The first type is better for irrigation than the second. The amounts of iron and nitrogen and their relations to each other are indicated by the following table. Only such samples are MINERAL QUALITY. 71 included as were collected with the precautions prescribed for the waters from the surface deposits. Content of iron, free ammonia, and nitrates in the Cretaceous waters, southern Minnesota. [Parts per million.] Group. Number of analyses. Total iron (Fe). Free ammonia (NH 3 ). Nitrate radicle (N0 3 ). 4 14 2.5 .5 2.1 2.0 0.1 .0 The hard Cretaceous water, like the deep drift water, is rich in iron and ammonia and is virtually devoid of nitrates. As in the case of the drift, this is probably" to be explained by the deficiency of oxj^gen. The soft water is like the hard in containing much ammonia and essentially no nitrates, but it stands in sharp contrast Parts per million Soft-water av srage \ ' V \\ \ v \\ \ " \ v \ \ / \ \ \ \ \>''' *' /\ /' / \x aa a ft a; A o o bo o 03 s ft 3 m 2 o Feci. 430 8 3 372 586 189 90 260 12 4 346 473 220 no 945 13 3 839 519 730 463 1,000 10 3 929 600 416 791 1,100 10 3 788 378 1,098 208 368 173 60 289 401 . 897 26 1,700 114 51 262 393 623 64 Northwest city well, Wahpe- ton, N. Dak Well of John Lockman in Breckenridge, Minn "Workman's well," Aber- deen, S. Dak "Artesian well," Aberdeen, S. Dak Andover, S. Dak Bristol, S. Dak.a City artesian well, Webster, S. Dak Sept. 28, 1907 do Oct. 31,1907 do Nov. 18,1904 May 20,1907 June 30,1905 1,004 949 2,318 2,445 2,295 1,642 1,332 <* It is not certain that this water comes from the Cretaceous. Mineral quality. 73 Analyses 1 and 2 were made for this survey by H. A. Whittaker, chemist, Minnesota state board of health. Analyses 3, 4, 5, 6, and 7 were furnished by G. N. Prentiss, chemist, Chicago, Milwaukee and St. Paul Railway Company. It is significant that the analyses here given can also be divided into two groups, one containing hard and the other soft water, and that all of the main generalizations made above with respect to the Cretaceous waters of southern Minnesota will hold in regard to these analyses. As far as known, the Cretaceous water of the Red River region belongs to the soft group. In an investigation conducted by J. H. Shepard a of the South Dakota Agricultural College, it was found that two types of Creta- ceous water exist in South Dakota. The water of one type is rich in calcium and magnesium, and is therefore hard; that of the other type is poor in these elements, and is consequently soft. As in Min- nesota, the soft water contains more sodium and chlorine, but some- what smaller amounts of sulphates than the hard, and it holds very little iron, while the hard water holds relatively much. Moreover, according to Shepard, the soft water comes from a higher horizon than the hard. The former he designates "first flow" water, and the latter "second flow" water. In the following table the averages of the analyses of each group are given, and in figure 5 the relations of the two groups are shown by means of the dotted lines. This figure shows that the two South Dakota types correspond to the two types found in Minnesota. It would be hazardous, from the data here considered, to correlate the 250-foot zone at Marshall with the "first flow" stratum of South Dakota, and the 400-foot zone at Marshall with the "second flow" stratum of South Dakota; but the fact should not be overlooked that these groups of analyses bear important and reliable evidence of the general correlation of the Minnesota Cretaceous with the Cretaceous of South Dakota. Average content of the two groups of Cretaceous waters in South Dakota. [Parts per million.] Group. Number of analyses. Calcium (Ca). Magne- sium (Mg). Eodium (Na). Sulphate radicle (SO*). Chlorine (CI). Total solids. 10 10 27 279 20 79 773 249 4f>5 770 4S0 145 2,261 2,019 ARCHEAN-CRETACEOUS CONTACT ZONE. Two samples were analyzed, one of water which comes from near the contact of the Cretaceous and the decomposed upper portion of a Shepard, J. H., The artesian waters of South Dakota: South Dakota Agr. Coll. and Exper. Sta. Bull. No. 41, 1895. u UNDERGROUND WATERS OE SOUTHERN MINNESOTA. the granite, and the other from the white kaolin that lies between these two rock systems. In both places the yield was extremely small. The analyses are given in the following table: Two analyses of waters from the Archean- Cretaceous contact zone in Lyon County. [Parts per million.J No.« Calcium (Ca). Magne- sium (Mg). Sodium and po- tassium (Na+K). Bicar- bonate radicle (HC0 3 ). Sulphate radicle (SO*). Chlorine (Ci). Total solids. 18 19 38 89 32 69 934 611 85 254 258 778 1,340 5S0 2,669 2,274 The two samples are somewhat similar, and they are most closely allied to the soft Cretaceous waters. Their most distinctive charac- teristic is the quantity of sodium chloride (common salt) which they contain. The mineralization is probably derived from the Cretaceous sediments and not from the Archean residuum. PALEOZOIC FORMATIONS. The following table, compiled by M. L. Fuller, shows the average composition of the waters from the various Paleozoic formations, based on a large number of reliable analyses: Average composition of waters from the various Paleozoic formations. [Parts per million.] Formation. Num- ber of analy- ses. Calcium (Ca). Mag- nesium (Mg). Sodium and po- tassium (Na+K). Bicar- bonate radicle (HCO3). Sulphate radicle (SO.). Chlorine (CI). Total solids. Devonian sandstone 1 10 14 14 11 35 3 8 5 6 2 1 2 4 21 66 94 84 74 92 80 87 88 61 134 86 99 92 93 77 12 25 30 25 37 30 31 27 22 20 53 30 17 34 28 6.7 41 20 14 23 31 15 37 36 98 16 9.4 75 95 36 276 366 372 346 433 359 316 319 258 328 349 431 466 422 342 18 95 61 25 52 75 85 36 59 347 40 38 57 44 60 9 9.5 8 4.1 8.4 13 22 38 45 29 6.1 1.2 15.7 109 36 269 482 St. Peter sandstone New Richmond sandstone Shakopee and Oneota dolomites Jordan sandstone St. Lawrence formation. . Dresbach sandstone Lower sandstone 430 336 409 445 430 345 400 St. Peter, New Rich- mond, and Jordan 739 St. Peter, New Rich- mond, Jordan, Dres- bach, and lower sand- 363 New Richmond, Jordan, Dresbach, and lower 391 Jordan and Dresbach 509 Jordan, Dresbach, and lower sandstones Dresbach and lower sand- 483 418 The above table shows (1) that the average waters from all the Paleozoic formations are moderately mineralized; (2) that calcium, a The number is that under which the analysis is given in the table accompanying the Lyon County report (p. 251). MINERAL QUALITY. 75 magnesium, and the bicarbonate radicle are the principal ingredients; and (3) that only minor quantities of chlorine and the alkalies are usually present. The tables accompanying the various county reports, however, show that some of the Paleozoic waters are highly mineralized, similar to the Cretaceous and drift waters of the south- western part of the State; and this is perhaps generally true in the southwestern province, where the Paleozoic strata extend beneath beds of Cretaceous from which they probably derive much of their water. The average water of this group has considerable temporary hard- ness but less permanent hardness. It deposits scale that is only moderately hard, and it will not readily foam nor will it corrode the boilers in which it is used. The table reveals no important differences in the total solids nor in the chemical composition of the waters from the various Paleozoic formations, except that the waters from the sandstones are perhaps not quite as hard as those from the limestones, and the waters from the lowest beds are distinctly richer in chlorine than those from higher horizons. SIOUX QUARTZITE. The following table gives analyses of waters from the Sioux quartzite : Analyses of waters from the Sioux quartzite. [Parts per million.] County. Jackson Pipestone.. Jackson Pipestone.. Do Rock Pipestone.. Do Watonwan. Rock Highest. Lowest.. Average. No. a Calcium (Ca). 277 160 130 104 85 81 72 48 27 15 277 15 100 nesium (Mg). 149 49 41 36 28 19 10 149 9 49 Sodium and po- tassium (Na+K). 134 33 276 110 20 7 38 16 532 2 532 2 117 Bicar- bonate radicle (HCOs). 489 620 692 372 351 310 317 261 199 58 692 58 367 Sulphate radicle (S0 4 ). 877 41 886 368 89 45 59 16 389 24 16 279 Chlorine (CI). 33 8 31 45 36 11 532 5 532 5 81 Total solids. 1,807 845 1,855 833 442 393 425 269 1,618 106 1,855 106 859 There is an enormous range in the total solids and in all of the constituents contained in the various quartzite waters. The ex- planation of this is evident. The quartzite itself contributes very little to the water, and thus in an area where it occurs at the sur- face the rain enters the rock at once and remains virtually free of dissolved substances. Analysis 3 in Rock County shows a remark- ably soft and slightly mineralized water. It comes from a spring at the margin of a quartzite plateau which is here covered with only 1 The number is that under which the analysis is given in the table accompanying the corresponding county report. 76 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. a few feet of drift. The rain soaks at once into the crevices of the rock and emerges at a lower level, having dissolved very little of any mineral constituent. In a district deeply covered with drift, the water falling as rain has a long, history previous to its entrance into the quartzite, and its mineralization is similar to that of other waters in the drift. Analysis 10 in Jackson County is characteristic of this type. This water comes from a well that passes through more than 100 feet of drift before entering the rock. It is extremely hard and is com- parable to some of the most highly mineralized drift waters in the same region. Again, the quartzite no doubt comes in contact with Cretaceous and other stratified formations, and from these may receive waters that are characteristic of the source from which they come. Analysis 13 in Watonwan County probably belongs to this class. Many of the quartzite waters are nearly free from iron, and the few analyses at hand show an absence of ammonia. The quartzite contains essentially no available iron, nor anything that will con- sume oxygen; hence it may be assumed that in localities where it lies near the surface, its water will retain its atmospheric oxj-gen and will be poor in both iron and ammonia. The water pumped from this formation is quite free from the fine suspended matter which is frequently present in water drawn from the incoherent sediments of the drift and Cretaceous. Where it is also free of iron, it retains, after reaching the air, a perfect absence of turbidity perhaps never found in drift and Cretaceous waters. SUMMARY. The following table shows the average composition of the prin- cipal groups of water discussed in this chapter (see also PI. Y): Average composition of the principal groups of underground ivaters. [Parts per million.] Formations. Num- ber of analy- ses. Calcium (Ca). Mag- nesium (Mg). Sodium and po- tassium (Na+K). Bicar- bonate radicle (HCOs). Sulphate radicle (SOO. Chlorine (CI). Total solids. Glacial drift and other surface deposits: Southeastern prov- 86 88 25 29 17 15 137 10 88 191 135 7-4 26 210 84 100 31 58 47 35 10 74 29 49 23 8S 44 65 500 215 34 117 372 499 446 507 414 445 358 367 62 542 154 .48 5S4 837 74 279 24 21 53 10 146 35 21 81 438 Southwestem prov- 1 132 North-central prov- ince- Depth less than 100 feet 673 Depth more thau 100 feet 513 Cretaceous: MINERAL QUALITY. 77 In conclusion, the following general facts can be pointed out: 1. The average composition of the waters from the glacial drift and other surface deposits in the southeastern province is essen- tially the same as that from the underlying Paleozoic formations in the same region. 2. The average composition of the waters from the glacial drift and other surface deposits in the southwestern province is similar to that of the hard waters from the Cretaceous strata in the same district, except that the content of sodium, potassium, and sulphates is much less. 3. In average composition the waters from the glacial drift and other surface deposits of the north-central province are intermediate in nearly every respect between those from the same deposits in the other two provinces, the water from shallow sources in general resembling that in the southwestern province, and the deeper water resembling more nearly that in the southeastern. 4. The least mineralized waters are those from the Paleozoic for- mations and from the drift and other surface deposits in the same area; the most highly mineralized are the Cretaceous waters, while next in rank are those from the drift in the southwestern (Cretaceous) province. The waters from the Sioux quartzite range from very low to very high. 5. The softest waters are those of the soft-water group of the Cretaceous, while the Paleozoic waters, those from the drift and other surface deposits in the southeastern province, and those from the lower portions of the drift in the north-central province are only moderately hard. The hardest waters are those belonging to the hard-water group of the Cretaceous and those from the drift in the southwestern province. The waters from the Sioux quartzite range from very soft to very hard. 6. The Paleozoic waters and those from the surface deposits in the southeastern province contain the smallest amounts of alkali, while the Cretaceous waters, and especially the soft Cretaceous waters, contain the greatest quantities. The quartzite waters range from very low to very high in their alkali content. 7. The range in the amount of combined carbonic acid (bicar- bonates) is much less than that of any other constituent. This is true of every group of water in southern Minnesota and of all the groups taken together. The waters in the eastern part of the State average somewhat lower in this respect than those in the western, but the difference is not great. None of the analyses made for the Survey showed the presence of normal carbonates. 8. The Cretaceous waters and the waters from the surface deposits in the southwestern province contain notable quantities of sulphates. The Paleozoic waters and those from the surface deposits in the 78 UNDEEGEOUND WATEES OF SOUTHEEN MINNESOTA. eastern part of the State have a considerable range in the quantity of sulphates they contain, though usually only moderate amounts are present. In the upper portion of the drift in the north-central prov- ince the sulphate content is generally high, while in the lower por- tion it is usually very low. In the quartzite waters the range is great. 9. In chlorine the soft Cretaceous waters rank highest, some being distinct]} 7 salty to the taste. The hard Cretaceous waters and the deepest Paleozoic waters also contain considerable quantities of this element, but the normal waters from the glacial drift and other sur- face deposits throughout southern Minnesota and from the upper formations of the Paleozoic generally contain only small amounts. 10. The deeper drift waters and the hard Cretaceous waters are usually relatively rich in iron and free ammonia and poor in nitrates, while the very shallow drift and alluvium waters and other waters containing free oxygen average lower in iron and ammonia and higher in nitrates. The soft Cretaceous waters are relatively low in iron and nitrates, but relatively high in ammonia. The relations of these three constituents to each other are shown by the following summary table, which is based chiefly upon analyses of samples from the sur- face deposits and Cretaceous: Relations of iron,Jree ammonia, and nitrates to each other in underground icaters of south- ern Minnesota. [Parts per million.] All groups except soft Cretaceous water. Soft Cretaceous water. Iron (Fe). Number of analy- ses. Free ammonia (NH 3 ). Nitrate radicle (N0 3 ). Number of analy- ses. Free ammonia (NH 3 ). Nitrate radicle (NO3). 8 3 7 13 13 16 9 2 0.02 .01 .02 .78 1.11 1.26 1.67 1.16 19.2 31.7 22.6 .5 .1 .3 .1 .0 3 3 3 3 1 1 2.46 0.0 0.1 .0 0.2 1.17 3.38 1.01 1.69 .0 0.3 to 1 .0 1 to2 .0 2to3 .0 3 to 5 PROBLEMS RELATING TO WELLS. By M. L. Puller and O. E. Meinzer. To explain the advantages and disadvantages of the different types of wells for the various conditions found in southern Minnesota, and to discuss the multitude of problems that are confronted in construct- ing and finishing these wells, would require an extensive treatise. In the following pages only a few subjects pertaining to wells are con- sidered — subjects which are especially important for the area under consideration, PROBLEMS RELATING TO WELLS. 79 TYPES OF WELLS. IN THE SURFACE DEPOSITS. -Casing -Pump rod -Casing -Pump pipe -Pump rod A majority of the wells of southern Minnesota draw their water from the glacial drift. Since the drift sheet, which is spread over most of the region, is but slightly eroded and poorly drained, and since much of the loosely aggregated material near the surface is more or less porous, small supplies of water are generally found near the surface except in periods of prolonged drought. It was a simple matter for the pioneer to dig down to water, and the shallow dug well was therefore at first the prevailing type wherever the drift was suffi- ciently deep and undissected. Later well augers or boring machines were introduced, with which it was pos- sible to penetrate the incoherent deposits more readily. By the use of these machines wells were con- structed that have a somewhat smaller diameter and greater depth than those dug by hand, but which resemble the latter in principle. In both types it is difficult to sink deeper after a saturated sand bed' is reached, and hence weak surficial water horizons are utilized and reli- ance for obtaining a sufficient supply is placed chiefly in the large diame- ter and the pervious casing (com- monly consisting of boards), by means of which the seepage is re- ceived from an extensive surface. Because of its large diameter, such figure e.-Diagram showing the two most com- a well also serves as a reservoir, mon types of deep-wen pumps. gradually filling up to the ground-water level, and thus accumulating a store of water during the intervals that it is not pumped. A bored or dug well is unsatisfactory in several respects. The constant fluctuation of the level of the water causes the wooden casing to decay rapidly, with the result that the clay and gravel on the sides cave and fall into the bottom of the well, soon filling it above the ground-water table. When the casing is partly rotted the well becomes a veritable trap for mice, rats, rabbits, and other small animals, which decompose in the water, producing conditions notori- -Valve of plunger -Valve ra Pump cylinder ■Valve of plunger -Valve -Water level Suction pipe "TUBULAR' INDEPENDENT PUMP 80 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Pump ■Drill rod ously filthy. Furthermore, in seasons of protracted drought the yield, which in most instances is normally small, becomes much reduced, or the well may dry up entirely, thus subjecting the farmer to great inconvenience. As the herds of live stock grow in size the difficulties attending an uncertain water supply increase in serious- ness, and as the farmers become prosperous many of them are ready to abandon their unsatisfactory shallow wells and to employ a driller to sink to stronger and more reliable beds at greater depths. The most common type of drilled wells ending in the drift is the so- called "tubular," which is cased with 2-inch iron pipe and terminates with a sand screen or strainer, through which the water is ad- mitted. In this type the plunger and valve are inserted in the cas- ing and there is no independent pump pipe (fig. 6). The wells are usually drilled by the "jetting" process, in which water constantly forced down through a hollow drill rod by means of a pump, is ejected with some force through a small orifice at the bottom and returns to the surface on the outside of the drill rod, carrying up the material that has been loosened by the drill or by its own impact. Another method, less frequently employed, is locally known as the "hydrau- lic" process. In this case water poured down the hole is forced up into the hollow drill rod with every downward stroke of the latter, and is prevented from returning by means of a valve. Thus the water is brought up carrying the drillings with it. Both methods are shown diagrammatically in figure 7. One of the principal diffi- culties met in drilling in the drift is presented by the glacial bowlders, which block effectually the progress of all driUs of frail construction. These obstacles can best be removed by the use of explosives. There are now numerous drilled drift wells of larger diameter, owned by municipalities, railway companies, and various manufactur- ing concerns, and not infrequently by farmers. A well more than 3 or 4 inches in diameter is usually made with a "standard rig," in ■Orifice -Drill "JETTING PROCESS" "HYDRAULIC PROCESS" Figuee 7.— Diagram showing two methods of drilling "tubular" wells. PEOBLEMS RELATING TO WELLS. 81 which a heavy percussion drill is suspended by means of a cable and is withdrawn at regular intervals in order that the drillings may be removed by lowering a bailer or "sand bucket." Virtually all drilled wells ending in the drift are provided with iron casing from top to bottom. While on a large proportion of farms the bored wells have been replaced by drilled ones, in most of the villages they are still in general use for furnishing domestic supplies. Dug wells of great diameter, sunk into alluvial or outwash gravels, are frequently used for public and locomotive supplies. In the areas where sand or gravel lies at the surface, shallow, inex- pensive driven wells are the prevailing type and for the most part furnish very satisfactory supplies. Such a well consists merely of a perforated "sand point" attached to an iron pipe and driven into the sandy deposits either by means of mallets wielded by hand or by some contrivance similar to a pile driver. IN THE CRETACEOUS. The Cretaceous rocks consist essentially of soft shale and sandstone that can be penetrated quite as readily as the drift. Hard material, perhaps chiefly concretionary in character, is frequently encountered, but there are no erratic bowlders such as cause trouble in the drift. Most of the wells that draw from this system are of the small "tubular" type, and although generally several hundred feet in depth, are for the most part drilled with very light rigs, by the "jetting" process above described. Wells passing through the Cretaceous, like those in the drift, are cased throughout with iron pipes. IN THE PALEOZOIC. In the southeastern part of the State, where there is considerable relief and the rock lies near the surface, the drift does not always supply enough water even for farm use, and consequently numerous wells have been drilled into the Paleozoic formations. Since in many places on the uplands the distance to water is great, many of these wells are deep. For penetrating the indurated limestones, shales, and sandstones of the Paleozoic, relatively heavy percussion drills are necessary, and it is not found advantageous to have the hole less than 5 or 6 inches in diameter. In most instances casing is inserted only to the unweathered rock, below which the well is open. IN THE SIOUX QUARTZITE. In the southwestern part of the State there are localities in which the Sioux quartzite (locally known as "the red rock") is so near the surface that little or no water is obtained from the overlying deposits. 60920°— wsp 256—11 6 82 TJNDEBGBOUND WATEES OF SOUTHEBN MINNESOTA. In these areas the problem of water supplies was at one time acute, but wells are now sunk into the rock and adequate quantities of water are secured there from. The quartzite is very hard, hence drilling into it is a slow and expensive process. Moreover, the mechanical difficulties prove quite insurmountable to anyone not skilled in this kind of work. Most of the wells are 6 inches in diameter and are made with heavy percussion drills. They require no casing nor screens, and when once constructed are permanent. IN THE AECHEAN. Although the Archean crystalline rocks are essentially not water bearing, much money has been expended in drilling into them, fre- quently to considerable depths. The admonition is here repeated that when unweathered granite or allied igneous rock is reached drilling should in all cases be discontinued. FINISHING WELLS IN SAND. THE PEOBLEM. Throughout the southwestern part of Minnesota and adjacent parts of Iowa and South Dakota the majority of drilled wells end in sand belonging either to the glacial drift or the Cretaceous system. The successful finishing of these wells is perhaps the most important prob- lem in connection with water supplies in this area. Most of them have 2-inch iron casing which serves also as the pump pipe (fig. 6.). The sand rises with the water so persistently that it is found necessary to put a screen or strainer at the bottom of the casing to shut out the sand while admitting the water. Various types of screens are in use, but the common type for wells of small diameter consists of a per- forated iron pipe surrounded by a brass gauze of fine mesh, and the whole inclosed in a perforated jacket to protect the gauze. The screen is small enough so that it can be let down inside the casing. Wells finished in this manner prove satisfactory for a time, but in the course of a few years the yield diminishes and eventually almost no water can be obtained. When the screens are removed they are found to be effectually sealed by a coating of silt, etc., firmly cemented into a hard impervious mass. The cost of a screen is not great, and the substitution of a new one for the old every few years would be no serious matter were it not that the removal of a screen is attended by great difficulties. In many instances the coating of cemented silt becomes so thick that the screen can not be withdrawn on the inside, and it is then necessary to pull up the entire casing in order to remove it. The labor and difficulty involved in this process are considered by many drillers to be equivalent to those of sinking a new well. PEOBLEMS RELATING TO WELLS. 83 Moreover, the rusted casing is liable to break, or the hole may cave in, and the well is then usually lost. The clogging of the screen has been found to be so great a nuisance that in many localities the drilled wells have nearly all been abandoned and shallow sources are again resorted to. Especially has this been done in the recent years of abundant rainfall, following a series of dry years in which many of the drilled wells were sunk. The aggregate cost of the wells that have thus been abandoned in this region amounts to hundreds of thousands of dollars, and, furthermore, the return to shallow wells is not a solution of the problem. In recognition of the magnitude of the difficulty the entire matter was investigated with a view to finding a practical remedy. CHEMISTRY OF THE INCRUSTING PROCESS: In order to ascertain the composition of the incrustant and the chemical changes involved in the incrusting process, a typical 2-inch well was selected from which had recently been removed a screen of the ordinary construction, coated with the usual hard, dirty-gray substance. The water from this well and the incrusting material were both analyzed. The well is owned by George Clynick and is located in the SW. { sec. 33, T. 104 N., R. 29 W., in Martin County, Minn. It was drilled in 1S99 and is 70 feet deep and 2 inches in diameter. It yields all that the windmill can pump. The head is 13 feet below the surface. In drilling the material penetrated was (1) blue clay; (2) bluish-white sand, at first very fine but changing to coarse grit, in which the well ends. The well has an iron casing, with a screen at the bottom. The screen is a perforated galvanized iron pipe surrounded by brass gauze, the whole inclosed in a perforated brass sheath. It is 3 feet long and about 1 inch in diameter. The length of time required for it to become effectually clogged is reported to be about five years. Analysis of water in clogged well. [Date, July 25, 1907. Analyst, H. A. Whittaker, chemist, Minnesota state board of health.] Parts per million. Silica (Si0 2 ) 24 Iron (Fe) 2. 6 Calcium (Ca) 140 Magnesium (Mg) 54 Sodium and potassium (Na-f-K) 22 Carbonate radicle (C0 3 ) Bicarbonate radicle (HC0 3 ) 259 Sulphate radicle (SO<) 389 Chlorine (CI) 4 Nitrate radicle (N0 3 ) 1. 5 Free ammonia 2. Carbon dioxide (C0 2 ) 54 Total solids... , , 772 84 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Analysis of material that incrustcd screen in clogged well. [Date, Sept. 26, 1907. Analyst, R. B. Dole, U. S. Geological Survey.] Clay, sand, silica, etc 56. Oxides of iron and aluminum (Fe 2 3 +Al.,0 3 ) 2. 8 CalciUm (Ca) 13. Magnesium (Mg) 1.3 Alkalies (Na+K) 7 Carbonate radicle (C0 3 ) 20. 6 Sulphate radicle (SO<) 4 Chlorine (CI) 1 Phosphate radicle. (PO) Organic and volatile matter 5. 3 100. 2 To the above analysis the following note was added : Of the 56 per cent comprising the silica and insoluble silicates, only 31 per cent is volatilized by hydrofluoric acid, showing that there is probably considerable clay present. Indeed, clay, sand, and carbonates of calcium and magnesium comprise 90 per cent of the deposit. The probable presence of sand particles is indicated by the fact that the substance was gritty when first pulverized and required two days' grinding to reduce it to a powder fine enough for analysis. The principal cementing substance is probably calcium carbonate precipitated from the water. The sand, silt, and clay are packed about the screen by the inflow of the water, and the interstices are then filled with calcium carbonate and other materials. Thus the whole becomes a nearly impervious sheath which shuts out the water. Whenever in any well the pump is operated the weight of the water column is decreased by the removal of water, and it is this diminution in pressure that causes a new supply of water to flow through the screen into the well. The reduction of the pressure may allow a portion of the carbon dioxide to pass out of solution, dis- turbing the equilibrium between the free carbon dioxide and the bicarbonate radicle and effecting partial decomposition of the latter substance. As a result of this reaction, calcium carbonate is prob- ably precipitated and is incorporated in the incrusting material. Only minute quantities of calcium carbonate need be deposited in order to effect the sealing of the screen in the course of several years. Possibly precipitated iron also adds to the cementing material. Electrolysis may occur between the brass and iron portions of the screen, but does not seem to be an adequate cause. City and village wells are usually provided with large brass screens, and these do not appear to cause as much trouble as the ordinary screens in the 2-inch farm wells, but brass screens in the 2-inch farm wells become incrusted as readily as the ordinary brass and iron ones, and the incrustant appears to be of the same character. If the diagnosis given is correct, the process does not depend chiefly upon the nature PEOBLEMS RELATING TO WELLS. 85 of the screen, but upon changes that unavoidably accompany the withdrawal of water from the well, and hence the remedy must be sought along mechanical rather than chemical lines. REMEDIES. A study of the mechanical aspects of the problem makes it possible to put forth some suggestions, which, if followed, should prove of value, diminishing the annoyance and expense connected with wells finished in sand. A well of large diameter and open end. — Two-inch wells should not be drilled in regions where the screens become incrusted. For farm purposes wells from 4 to 6 inches in diameter can generally be fin- ished successfully with open ends, whereas it is invariably necessary to put screens into those which are only 2 inches in diameter. The explanation is simple. With a given rate of pumping the upward velocity of the water in a well varies inversely as the square of the diameter; while the capacity of a current to move solid particles has been proved to vary as the sixth power of the velocity. Consequently sand that will cause no trouble in a large well will be driven rapidly into a small one if it is not screened. Practically the effect is prob- ably even greater than the above ratio indicates, because in the wells of large diameter the inflow and upward velocity are nearly constant as long as the rate of pumping is kept constant, while in a well of small diameter the casing usually serves also as the pump pipe, and hence the upward current is not uniform, being zero during the down- ward stroke and varying from zero to a maximum and back to zero during the upward stroke. This can be better understood by refer- ence to figure 6. In general it will be found more satisfactory and ultimately more economical to drill wells at least 4 inches in diameter than to put down the small 2-inch "tubulars." It is important, however, to understand that the finishing of sand wells with open ends should be attempted only where the rate of pumping is to be slow, for example, in farm wells where windmills are used. As a rule wells furnishing water for public supplies and all others pumped by steam or gasoline engines should be provided with screens. A number of sand wells used for public supplies in southern Minnesota were finished without screens and nearly all of these have given trouble. The sand rises with the water, cutting out the pump valves, clogging the mains, and filling the wells to such an extent that the supply is greatly diminished or the wells are totally ruined. A well of large diameter finished with a screen. — Drilled sand wells of large diameter invariably require screens if the rate of pumping is to be rapid, and some require them even though the rate of pumping is slow. Whenever there is danger that the sand will rise it is the 86 CJNDERGROUND WATERS OF SOUTHERN MINNESOTA. part of discretion to put in a screen. It should be remembered, however, that a JV-ineh well with a screen is much better than a 2-inch well similarly finished. In the latter the screen must of neces- sity tit snugly into the casing, and when it becomes incrusted it is liable to refuse to come up, thus causing much trouble and fre- quently making it necessary io pull the entire casing. In a 5-inch Well, on the other hand, a small enough screen can be used so that there will be no difficulty in removing it. Experience shows that it is poor economy to drill --inch wells. Finding a coarse layer. -The glacial deposits, in which ninny of the wells under consideration end. are irregular and may alternate rapidly from tine sand to coarse gravel. It is a matter of great importance to finish a well where the material is coarsest. Drillers understand the significance of this but are not always successful in practice. As a rule, the coarsest part of a sand and gravel bed is at the bottom, but this is not invariably so. Driving the easing to the proper depth. — Commonly a thin layer of "hardpan" lies at the contact between a bed of clay and a deposit of water-bearing sand and gravel. Frequently there is difficulty in driving the easing through the "hardpan," and hence it is often allowed to stop above this hard layer or to tit only loosely into it. If a screen is inserted it is somewhat smaller than the casing and can easily be projected through the hole in the "hardpan" and into the water-bearing sand. This is a careless method of finishing a well. The clay is liable to be washed down and to come in contact with the screen, thus greatly hastening the clogging process; or if the well has an open end the caving of the clay may obstruct the entrance. Not infrequently wells are ruined by neglect of the driller in this respect. Whether they are to be finished with or without a screen, it is important to have the easing driven com- pletely through the cap of "hardpan" and down into the coarsest part of the sand or gravel. Developing a natural sereen. -Glacial deposits, and to some extent also Cretaceous strata, are poorly sorted, tine sand and coarser grit generally being more or less mixed together. When a well is to be finished in one of these deposits it should be pumped for a pro- tracted period in such a manner as to remove the fine silt ami leave a natural screen of coarser material. This frequently makes it pos- sible to finish the well without a screen where otherwise one would have been required, but it should be done even where a screen is inserted. Proper treatment in this respect requires patience and skill, but it undoubtedly results in superior wells. Making an artificial graeel screen. — The process of developing a natural sereen is sometimes supplemented by introducing into the well a quantity of gravel o crushed tile of the proper coarseness. PROBLEMS RELATING TO WELLS. 87 This method has proved successful with drillers who arc; willing to devote sufficient time and effort to it 7 and often makes it possible to finish a well without putting in an ordinary screen. An independent pump. — As has already been explained, in 2-inch wells the casing usually serves also as the pump pipe; a device that produces more or less unsatisfactory results. The water must enter as rapidly as it is drawn up by the pump. This gives an intermittent and irregular current into the well and increases greatly the danger of drawing up sand. Even where a screen is used it is liable to force fine silt through the meshes or to break holes in the screen, and the great reduction of pressure in the well on the upstroke probably increases the precipitation of calcium carbonate. When the yield is small or when the inflow of the water is obstructed by the incrusting of the screen, pumping becomes difficult and the wear and tear become great. An independent pump hung in a well of adequate diameter involves some additional cost, but is much more satisfactory. Removing the screen frequently. — Much of the difficulty with the screens could be avoided if they were renewed more frequently. A screen which is left in the well until it has become so completely sealed that its removal is absolutely necessary not only is an aggravation for a long time before its removal, but also is likely to have become so thickly coated that it can not easily be withdrawn. Summary. — Only wells of large diameter should be drilled (that is, 4 inches or more). Care should be taken to drive the casing through the cap of "hardpan" and through any beds of quicksand which may exist, to the coarsest portion of the deposit. The fine sand should then be removed by protracted pumping and a natural screen of coarser sand or gravel developed. Gravel of the proper coarseness may also be introduced into the well to be added to the natural strainer. If the water is to be drawn at a slow rate and an inde- pendent pump is used, it is not usually necessary to put in a metal screen. If, however, the water will not become clear and the sand persists in rising, a screen should be inserted and tightly attached to the bottom of the casing. It should be considerably smaller than the latter in order that it can easily be removed when it has become incrusted. As soon as the yield of the well shows distinct signs of reduction, the screen should be drawn up and cleaned or else replaced by a new one. DRILLING IN QUARTZITE. The Sioux quartzite ("red rock") presents a group of difficulties which are exceedingly troublesome to any driller not accustomed to penetrating this formation, but if these difficulties are foreseen and properly guarded against they become much less serious. The following are some of the principal points that must be observed: 88 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. (1) The machine must be strong and heavy. Many of the rigs that are satisfactory for sinking into the drift and Cretaceous are entirely inadequate for hard rock drilling. (2) The well must be large enough to admit heavy drill rods. A hole 6 inches in diameter can perhaps be drilled -more advantageously than any larger or smaller size. (3) The drill must be kept properly sharpened and tempered. It is customar} T to have the outfit include a forge and to be equipped with two drills in order that one can be sharpened while the other is in service. The length of time a drill can be used advantageously before it is exchanged for a newly sharpened one varies with the hardness of the rock, the average period being about forty minutes. (4) The drill must be kept up to the standard diameter. As the hard rock abrades its sides, it gradually becomes smaller and makes a hole of diminished diameter. When once the size of the hole has been reduced, it is well-nigh impossible to enlarge it. Thus it hap- pened, before this contingency was vigilantly guarded against, that the well would persistently shrink in diameter as the work progressed, until it was no longer feasible to continue drilling. It is now the a & practice to restore the drill to its standard diameter each time it is removed and sharp- ened. (5) The well must be kept straight. Its obstinate tendency to become crooked was oft perhaps the greatest difficulty encountered Soft Hard ^ HarcT^ v by the pioneer rock drillers. This may be FrouKE 8.-Diagram showing ihe caused h J the presence of " crevices " which deflection of the drill in Sioux the drill persists in following, instead of cut- quartzite. ^ straight downward into the hard rock. More commonly perhaps it is due to the fact that there are great differences in the degree of induration. Thus when the drill passes from a relatively soft portion into harder rock (the contact plane between the two being oblique), instead of going directly downward into the hard rock it tends to follow the contact plane and to remain in the soft portion (fig. 8). It is about as difficult to straighten a hole that is out of alignment as it is to enlarge a contracted one, and the experienced workman is therefore watchful to prevent any departure from the plumb line. The principal precaution to be taken is to work with a taut cable when the drill shows a tendency to be deflected. PHENOMENA DUE TO VARIATIONS IN ATMOSPHERIC PRESSURE. FLUCTUATION OF HEAD. The fluctuations in the level to which water rises in wells are con- trolled by a number of factors, most of which (such as rainfall, melt- ing of snow, and freezing and thawing of the ground) relate to the supply contributed to the underground reservoirs. But attention is PROBLEMS RELATING TO WELLS. 89 here directed to a class of fluctuations more limited in their range and less frequently observed, but no doubt occurring very generally. They are the variations in water level resulting from the changes in the pressure of the atmosphere. An example is afforded in the vicinity of Winnebago, where it is reported that some of the wells show slight daily variations of level, the water frequently standing lowest at about 10 a. m., when the barometric pressure is usually greatest, and highest at about 4 p. m., when the pressure is likely to be least; while still greater fluctuations mark the passage of storms, the water rising materially with the decrease in pressure on their approach, and subsiding on the return of fair weather and a high barometer. VARIATIONS IN THE YIELD OF FLOWING WELLS. It follows as a corollary of what has just been said that the dis- charge from flowing wells is greater when the barometer is low than when it is high. Although this is perhaps a universal phenomenon, the difference in discharge is usually so small that it is quite unob- served. However, where the artesian pressure is slight, as in many of the drift and Paleozoic wells of the region under consideration, the effect of the fluctuations in atmospheric pressure is frequently apparent, and it sometimes happens that a well will flow during storms but will cease flowing when the weather clears up. The well of the Red Wing Malting Company, 470 feet deep and ending in sandstone, is said to flow 25 per cent more when the wind is north- east (during storms) than ordinarily. ROILINESS OF THE WATER DURING STORMS. Most wells, except when first sunk, yield clear water. In isolated cases, however, the water, which is ordinarily clear, becomes cloudy or milky on the approach of storms, and more rarely it turns to a bright yellow or deep red color under the same conditions. Among the instances of milkiness before storms may be mentioned certain wells near Lakeville in Scott County, while of discoloration the most pronounced examples are in the vicinity of Waterville in Lesueur County. Examination shows the milkiness to be due to the presence of a slight amount of suspended silt or clay, and the yellow and red colors to fine particles of iron oxide held in suspension. Since this phenomenon is closely associated with the changes in the weather, it is altogether probable that in some way it results from fluctuations in atmospheric pressure. In the case of flowing wells it could perhaps be explained by the increased discharge during low barometer, the water at these times having a greater velocity and hence being able to bring up sediment that usually remains 90 UNDEEGBOUND WATEES OF SOUTHEEN MINNESOTA. undisturbed. But the fact that the phenomenon occurs also in wells that do not flow seems to discredit such a hypothesis and leaves the precise explanation obscure. "blowing" and "breathing" wells. "Blowing" and "sucking" are common phenomena in southern Minnesota, not only in drilled wells, but also in those of the dug and bored types. In the latter the air passes in and out through open- ings in the curbs, in some instances with considerable force. Often the whistling of the escaping air is loud enough to be heard for several rods. In some wells in other sections of the country the current is strong enough to operate a whistle that can be heard at a distance of a mile or more. The indraft is usually less rapid and less conspicuous than the outward current, and in warm climates it is often overlooked, but its presence is abundantly demonstrated by freezing wells. In the majority of instances, however, the "blowing" is observed to be intermittent and to alternate with periods of "suck- ing." In this case the well is commonly known as a "breathing" well, or it may be aptly caUed a "barometer" or "weather" well. Since the "blowing" is commonly associated with a falling bar- ometer and the "sucking" with a rising barometer, it seems certain that they are caused by the variations of atmospheric pressure. The essential condition is that the well must be in connection with underground cavities not filled with water and not in free communi- cation with the atmosphere. This condition is common in the Paleozoic area, where formations of limestone are traversed by solu- tion passages forming a cavernous network, where these formations are now covered by drift or other relatively impervious material, where the ground-water level is often low, leaving the passages filled with air instead of water, and where the wells are generally not cased below the point at which they enter indurated rock. Porous gravels of the drift will serve the same function as the solution passages of the limestone, provided they he above the ground-water level and are not shut out by the casing. When, on the approach of a storm, the pressure at the surface is reduced, the air confined in the earth rushes out until equilibrium is reestablished; but when, upon the return of fair weather, the pressure again increases air is forced back through the well into the earth. In the few wells from which water is spouted during the period of "blowing," the casing probably extends virtually to the water, but not far below it. Some of the "blowing" wells of southern Minnesota will be briefly described. (1) In a number of the valleys between Wabasha and Reads Landing and elsewhere in the same vicinity, a dozen or more wells are known which exhibit the phenomenon of "blowing," the air coming in strongly at depths of about 60 feet from openings in PKOBLEMS EELATING TO WELLS. 91 the limestone into which the wells are mainly drilled. (2) In the region of Waseca, under a layer of clayey hardpan at about 100 feet below the plateau surface, there appears to be a bed of coarse gravel which yields "blowing" wells whenever encountered, but which does not afford water. In one well of the group it is known that the "blowing" alternates with a "sucking" of the air. (3) On the prairies in the vicinity of Roberds and Cannon lakes, near Fari- bault, many "blowing" wells are reported. According to the local drillers the phenomenon is confined to uncased wells, the air being found in gravel beneath beds of clay, never in gravel near the surface. According to their statements, when the wind is from the south air is expelled with a whistling sound; when from the north it is drawn in. Poisonous gas is sometimes given off with the expelled air, occasionally producing fatal results. In winter, during periods of north wind, freezing occurs to a depth of 80 feet, notwithstanding the attempts to prevent it by coverings. (4) In Lac qui Parle County there are a number of "barometer" wells ending in gravel. In one of them water is forcibly ejected when a storm is approaching. FREEZING OF WELLS. At certain points in southern Minnesota much trouble is experi- enced from the freezing of the water in wells, and it is often only with the greatest difficulty that the wells are kept in use during the winter. It is known that the freezing takes place in the clear weather following a storm, when the barometer stands unusually high, while the wells thaw during storms or periods of low barometer. It is further noted in some wells that the freezing takes place when there is an inward current, while the thawing is associated with a discharge of air. These facts show that barometric fluctuation is the general cause of the difficulty. The freezing occurs in dug and drilled wells, but is not manifested in double-tube wells when both casings are carried below the water level, although where the outer extends only to the rock or stops at some other point before the water is reached there is danger of freezing. In some wells the mischief seems to be caused not by the air passing down on the inside of the casing, but by its penetrating on the outside or through natural passages intersecting the well. In the treatment of freezing wells the aim is either to warm the air passing in or to prevent its entrance. The most common method of accomplishing the first of these purposes is to pack manure about the top of the well, the heat generated by its decomposition tending to warm the air to some extent. This method should be condemned, since it involves the danger of polluting the water. A better remedy is to prevent the entrance of the air. If possible this should be done by carrying air-tight casings to a sufficient depth, 92 UNDERGROUND WATERS OE SOUTHERN MINNESOTA. but air currents can also be stopped by filling the space between the two tubes with some impervious material. A filling of cement rest- ing on an improvised plug is very effective, as is the use of rubber packers, where these can be secured. The homemade rag packing is unsatisfactory, as it is generally sufficiently porous to permit the air to get in. Where the air does not enter through the well, but passes down on the outside or circulates in underground passages intersect- ing the drill hole, it may be advisable to fill the space between the outer and inner tubes from top to bottom with cement. In dug wells the remedy lies not in housing the well, a method that has been found unsuccessful, but rather in making an air-tight curb of cement or other material tightly fitted to the well curb, which should also be lined with cement for some feet below the surface to prevent the entrance of air through the soil. DRAINAGE BY WELLS. THE PROBLEM. Over much of the drift-covered uplands of southern Minnesota the ground-water level is near the surface, and numerous undrained depressions exist as swamps or lakes. The soils of such depressions are usually rich, and when reclaimed yield splendid crops, tracts originally almost worthless being converted to valuable farming lands that add materially to the productiveness of the region. Artificial drainage, therefore, is a problem of great importance. Cooperative drainage by ditching is undoubtedly the best general method, and is the one commonly employed where the relief is suffi- cient to make it possible and where the wet lands are not separated from the drainage line by ridges of too great height. But where the topographic conditions are such that it is not feasible to conduct the water to a natural drainage channel, small tracts can in some cases be reclaimed by drainage wells. NECESSARY CONDITIONS. The efficiency of wells for drainage purposes depends upon the difference in head of the surface and underground water, and upon the texture of the deposits into which the Water is introduced. The texture is important in determining the water-bearing capacity, the rate at which the water is conducted away, and the liability of the passages to become filled by sediment unavoidably carried down by the water. Of the various materials encountered in drilling, gravels are among the best for drainage by wells, since they not only have a high degree of porosity, averaging 30 to 35 per cent of their volume, but the openings are so large that they conduct water readily and do not PKOBLEMS RELATING TO WELLS. 93 easily become clogged by foreign matter. Sand, though fully as porous as gravel, offers more resistance to the passage of the water and has a greater tendency to become clogged. This latter difficulty is a serious obstacle to draining into sand, especially into the finer varieties. Of the consolidated materials in southern Minnesota, sand- stones and limestones only need to be considered. The former are rather porous, but present the same difficulties as unconsolidated sand. The limestone in itself is virtually impervious, but its bedding planes, joints, and solution passages afford ideal conditions for drain- age by wells. REMOVAL OF DEBRIS AND SEDIMENT FROM THE WATER. One of the principal precautions to be taken in connection with drainage into wells is to prevent the entrance of solid matter, which will in time partly choke up the pores of the formation into which the water is poured, and will thus greatly reduce the capacity of the well. This foreign material consists of two kinds — (1) floating vege- table matter in the form of leaves, twigs, grass, slime, etc., and (2) suspended particles of clay and silt. The floating matter can readily be strained out by allowing the water to pass through a screen. The particles of clay and silt are less easily removed. Perhaps the most feasible method is to have a settling reservoir, but it is possible that, under conditions otherwise favorable, some method of filtration could profitably be employed. If the wet land is drained through a sub- surface system of tiles, the water conducted to the well will be less burdened by sediment than if it flows upon the surface. EXTENT OF AREAS THAT CAN BE RECLAIMED. The number of acres that can be reclaimed with a well of a given diameter depends upon the factors already mentioned as governing the capacity of the well, and upon the quantity of water that must be removed per acre. In many cases not only the visible water but also the tributary ground water must be disposed of. Where the conditions are favorable, a single 4-inch well will sometimes remove ponds 2 or 3 acres in extent and drain land areas of 10 to 60 acres between the thawing in the spring and the time of planting." At a few places in southern Minnesota wells have been used for the drainage of wet lands. Six miles south of Blooming Prairie, Steele County, a well successfully drained several acres, while 3 miles south of Albert Lea a 3-inch well drained 5 acres. Similar results are said to have been obtained in other localities. If reservoirs were a Horton, R. E., The drainage of ponds into drilled wells: Water-Supply Paper U. S. Geol. Survey No. 145, 1905, pp. 30-39. Crider, A. F., Drainage of wet lands in Arkansas by wells: Water-Supply Paper U. S. Geol Sur%-ey No. 160, 1906, pp. 54-58. 94 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. excavated they would not only serve to free the water of sediment, but, by receiving the water at times of heavy rainfall, would keep the wells more constantly employed and would thereby increase their effective capacity. HYDRAULIC RAMS. The benefits resulting from the use of hydraulic rams have seldom been brought to the attention of the spring owners and the owners of flowing wells. The statement is often made by a property holder that he would give a considerable sum of money for a flowing well at his house like that of some more fortunate neighbor on lower ground, or for a spring like those in an adjacent valley. Of course the conditions may make it impracticable for a farmer to obtain such water at his home, but hi many localities the same advantages may be secured by installing a hydraulic ram. Given a flowing well or spring with a few feet of head and a moderate yield, this appliance can frequently be successfully used to lift an adequate supply of water to a house and barn at a considerably higher level. With 5 feet of head at the ram, the water may be conveniently raised to about 30 feet, while with large rams and favorable condi- tions of head and volume, water can be carried as much as half a mile and lifted 200 feet. The length of the supply pipe should be at least 30 or 40 feet to give the most efficient results. An actual test on a small ram costing $9, with 70 feet of supply pipe and 12 feet of fall, showed that with 2.1 gallons per minute furnished to the ram, 0.3 gallon was delivered through 100 feet of pipe at a height of 50 feet above the ram. The only cost of operating is that of repairs. Although not in common use in southern Minnesota, rams have, nevertheless, been employed hi a number of instances. At Hokah one has been used to pump the water from a 544-foot well with a head of about 18 feet, to the village 30 or 40 feet above it. At Sterling Center several of the flowing wells are connected with rams and the water lifted to the houses on the higher lands. The same is true of the flowing-well district about the head of Straight River in southern Steele County and near Geneva in northern Freeborn County. The heads are usually from 10 to 15 feet, the lift 25 or 30 feet, and the distance carried often several hundred feet. Rams are seldom used for pumping the water of springs, although in a number of instances this might readily be done. The largest springs, however, are often in deep valleys, such as those of the streams entering the Mississippi near the southeastern corner of the State. Here it would be necessary to lift the water greater distances than is practicable with rams. PROBLEMS RELATING TO WELLS. 95 SCIENTIFIC PROSPECTING FOR WATER. In southern Minnesota, as in other sections of the country, pros- pecting for water has been conducted in a desultory manner, and but little attention has been given to securing or preserving definite information in regard to the water horizons penetrated in deep drilling. Many of the deepest wells have been sunk by the munici- palities, at considerable cost; with only slight additional expen- diture data in regard to the underground waters could have been obtained which would be of great permanent value to the com- munities concerned. Random methods are just as extravagant in securing water supplies as in any other line of work, and precise information is of equally great value. It is desired here to make a plea for more intelligent action in the future. Whenever a community goes to the expense of sinking a deep well it should at the same time secure a record of its underground water resources to the depth drilled, and the contract made with the driller should provide for it. Approximately the following procedure should be observed: 1. Samples should be kept of all material penetrated and full descriptive notes made of everything found by the drill and of all difficulties or unusual conditions met in drilling. The record should include the exact thickness of each stratum and its depth beneath the surface. The drillings should be submitted for examination to a competent geologist. 2. All water-bearing strata should be described in special detail. If the material consists of sand, gravel, or sandstone, it is important to note the porosity, induration, and size of grain, as well as varia- tions with depth in any of these. 3. The height to which the water will naturally rise should be ascertained for each water-bearing stratum. The notes should state whether the water at higher levels was shut out by casing when the head was measured. 4. At each depth at which a new supply is encountered the yield should be tested. The record must show not only the rate at which the well was pumped, but also the distance that the water level was lowered thereby, and the length of time that the pumping was con- tinued. The best method is to insert the suction pipe a definite depth into the water and then determine the rate of pumping required to lower the water level this distance. By raising and lowering the pump very precise results can be obtained. Where the forma- tion consists of incoherent sand that persists in coming into the well it may not be feasible to make accurate determinations of the yield, but in this case the general conditions should be described. In all instances it is necessary to note whether the water comes from 96 UNDERGROUND WATERS 01 SOUTHERN MINNESOTA. only the lowest bed, the higher ones being shut out by casing, or whether water from different levels contributed to the yield. 5. The quality of the water from each horizon should be ascer- tained, as important results may thus be produced. Great effort should be put forth to obtain samples from each source unadulter- ated by the water from other levels. It may not be feasible to have a complete analysis made of the water from each depth, but the temporary and permanent hardness can at least be determined, and a few other simple tests made, winch will throw much light upon the character of the water. 6. In the well as finally completed, the length and diameter of the casing and the description of the screen (if one is required) should be noted in detail. The method of finishing the well, the difficulties encountered, and indeed the entire history of the process should be described. If the method above outlined is faithfully pursued, the community will have in its possession a reliable record of its water resources and underground conditions which will be of great intrinsic value. If a competent engineer or other person with expert knowledge is em- ployed to superintend the prospecting and to make and record the various tests, the data will of course be so much the more reliable and complete. In the future when new supplies are required for public waterworks, for industrial concerns, or for any other purpose, trustworthy information will be at hand, and this will make intelli- gent action possible and may show the way to a better supply than would otherwise be secured. Indeed, it may prove a distinct asset to the community, as far as industrial development is concerned. When, later, other deep wells are drilled, similar records should be kept, and these can then be compared and contrasted with the original and with each other, thus giving a body of information that will be far more comprehensive and reliable than the record of any single well. One of the greatest difficulties experienced, especially in the smaller settlements, is to retain such data as have been secured. With the frequent changes hi the official personnel, well records which were at first preserved are almost invariably lost sooner or later, and even the depth of the hole may become a matter of uncer- tainty. It is therefore important that special care be taken to preserve the record. Several copies should be made and deposited in different places for safe-keeping. It would be well to have one copy registered hi a county office in which permanent records are filed. If the drilling project ends unsuccessfully it should not be assumed that the record is, therefore, of no value. Negative facts are fre- quently worth as much as positive ones. Moreover, a knowledge of the difficulties that are to be expected may aid in a future drilling enterprise to overcome these obstacles and to achieve success. UNDERGROUND WATERS OF SOUTHERN MINNESOTA. 97 PUBLIC WATER SUPPLIES. By 0. E. Meinzer. GENERAL STATEMENT AND TABLE. In connection with the field work upon which this report is based the public supplies in the cities and villages of southern Minnesota were thoroughly examined, especial attention being given to the geologic and sanitary aspects of the source of the water. The inves- tigations in 1907 were conducted in cooperation with the Minnesota state board of health, and mineral, sanitary-chemical, and bacterio- logical analyses of most of the supplies were made in their laboratories. Later, through correspondence with the superintendents of the various waterworks, the statistical data were verified and corrected for January 1, 1908. This revised body of information forms the basis upon which the following table of public water supplies was con- structed. For the most part, the sanitary data do not appear in this paper, but are in possession of the state board of health, to be used as occasion demands. The present chapter is little more than a summarized statement of the information presented in the table. 60920°— wsp 256—11 7 98 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. S.S.s-1 ZJ— >- > (A >• p lOOiOJO IOO S* o ft r ^ o . n ^ 03*^ d *» su S3 s? OWcoH -^ o o o a 6 COCO Oaj O 3 R S ft — — ft=2 co ceZ -r so >o oc so ■** cccomQ ft ft ft £ § * p £ft S ^ 2 § h, sfl.2 o3v-,.2 £ 03« > fl g '-=33 .CO . Z Z Z £ R S w Z NO zjp'p'^z J zi _'iOiflO lO o o 33 -^ SO io cc so o O SO r-H en -h.-i I I I CO r-t CO I I I 00 « t- 03.^ D3 <~> E ' su . 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P^^^ CJ OJ GJ . , g«-S g 03 g So -OS 9S 1- §^ ^ 3 ^a «a o M ft3 «6 ■§ S s^ P L - ftS 0?^ CJ "9 £- £a5« 1 1 |5«a^ S»SS >.p C3 a> o> oi.SS 3.2 J= J3£!J2 cjj3 fig & « 5 o 03 ° , M * u 2 <^ .s-s-a ^ 3 ^^2 °b& ^a " s £ * ^ : ft ..^E'o3 iJfi^ o £ 2 IHPhP-^5 3-ft 108 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. £ o3 _ 3 "5 "° ■* oj.S C-.d W w ^ <- ^ 2g, 03.S 53^3 o T3 +^ >-^3 B C 2 h>h CM C3-* • o >o o o go 00 E2<© ,-( ^>H O r? O O 00000 00000 00000 00; o3 O 03 O 03 03 03 cE^ESE w X *-' CO W Oj t-i V P^Pupo, &.c+> 5 S £ g SI lOr-lO r-. O O L-" o o c Or-l r-l ** CO -e-N • --:u- Ao '.o pV§oT ^t Si QJ ^ 03 r 00000 3 -a*£5' a -a' J £ T3 -g P.-C £ "O *i "§ g-s-a'C-ot-SSggt-SS.S o : : : :o 000 ft § I fc ^-g O ^PCNI ^ 00 O^t^OlfTSO 000 o *tf c3 »o -** 1 ^ . 00-^"*? v-< 3 >>.:* p a> 3 p « fe - o - .i c c ftOhli'' 00 U— ■ i> l—t 1 ;-) ri -3 fflpqfflffl ffl WOooo "a : 03 >»2 S3 S'S* S - — O O 0000 OU jfiO PUBLIC WATER SUPPLIES. 109 03 TO 03 03 03 qj h fn fn g 03 u o co « tHt1< _o ® a 03 "03 £o3 ss O -*-* 1 w'S 03 +^<-T+^ fepqfct SS 03 03 (3 03 rH ,-H CO .CO 0505»O-^ 00 r:--i-^'4 nH< >> I : ; >> . : ■^•8 ti l^- >> Sh 03 i-i ravit do.. ra v and rect. ravit o o :o o lO i-H o -o o=3o O 03 >C o fin M ?" O.iOlO oo nm-* ihth ooo oo o o o o o ooo oo ONIO o o MOOO 03 oo'io 4^ +J . o o ' 03 03 >a ' H-U 03 ■ ^(-O g 03 g o &,£>«> ' c3§S§ ■£ ® 8 £ O ^H JOwN _J OOO fifi OOO m 2 T o o o »o O CO o'oT ooofi3 NHIOOOOD rH i-H CO i-l lOCN »OCN O O t^ CNl •V O O Ol i-H i-l ■ OJOOHOOC >!-H IMt-H i-lrH Or-HOO >> o ™ ^ o «N «H« i-fc* NUD^I ,-H r+*nN"i-d«jiH® sw -^ 5 03k_-rt C3 d S 03 S 03 OP OO ooo •a . ■ si'g •§ t "O -g ■§ ^ : oooo oo : wo OO t^ CO O ^* :_o3 :> 9 • 03 pi os3o« :.g : QOO OO oo 03 03 03 C3T3 ft flHK« os g c i; o fi 9-h a w S II Mil 1|§ ado PhPhPh 03 2 , ,.. ■S3 o3 o O [h 3 'iH t~Tl< OOl & . fl 3 E'Sp 03 03 t>>03 . fl bas o fc*, - 03 03 S"C 03 O So." ^(JfXfc e o u -a oo o O ® § c3 ;oov htH JOO OO . S 03 03 ^ ia oSs 03 {h td 03 03 ooww 110 UNDERGROUND AVATERS OF SOUTHERN MINNESOTA. C tf — S'S o ^.S ft£ +» ft'— a o ft B <" B- If 8 ' 681 a> o3 o _c3 cd EE c3 « EE 03 ffi £ !h^; irao _;o o oB3 o MKlfiiO 10 o o o o o r: :- ~. (M - CO ss nOiflOiONOiQN OliOH ■** >a> g SftSS r d- ) ; s aSiocc!B>';jofia 2>-&££'agfcHd£iS^'3s-3 oo o :oo oo : :o oo £. h, o.^ij £ -b u ^3 oo :qoo5o : o o c o x = ■: i-h o o -t ■* — - O i-l i-l i-H >-H ,-1 o o o o o ^ 'O 'O ^ X) s :o oo tD^Tjicoc O 3 ~ O C: X — C LC O M § : 1 : c : : o3 o3 o3 e3 o> ajooo 2 a » E? JS "5 f <" » « ^ ^ n n ^ * PUBLIC WATER SUPPLIES. Ill m o O O in t- IMIM CD 0J ° 3 e© sfeee w © cd - J n j s iCOO D g3 o3 c3 03 a) a) a« a> qj a> a feg g^^ss g§ [i, [=,£=, Sf^finfiH SSS S hS 03 qj 03 03 03 J*>H £ !* l?> 2 ^ OOiOiOO C~CN CN ** CO ICO CO O in O CO O C*~ CN CN COOCNOOCO ^-' o o o o o o o 00 O OlOLTlOO CM .-I OJt^WOT}* oomoo OiCNOO ;00O0 ? o in oo o o — ■ o o o c ^ iO w oo oo oo ocTo~ ooooo o o o o o OO OJOO O 00 i-l -- T-t T-H CM i-H ^H i-H > t=->.l S * 5 <° K ° ° , g.ng.hgT3T3! ofioflo : ic } C3 (_, fi C3 r oooo gT3 a : a > fi 03 F O - oo £ on; i; c: — :_ ;.. i_ ., . b :5o5o O OlO o o 00-*m^O o in o 'M o o : ^ CO GC u- X — ■ o o o o o o m in r- o »n ■<* -^ C3 oooooooo T3 'O ^ ^ 'O 'O 'O ^ o a> ■a.s 35. ° •; oo IOOIOOO Co ooc»; 3 j : :oflo oio onooo" ^ co ootaxC'J't 2 =3 P?C3° O (-, . O CD o ._ o c3 -O :/. ; ta -ScsS^ '. =3 •£ o a) a> > ojj3 g ft„ a) a e d S o c3 cSdc3S.S-S.H.SJ o oo o°J csaiiC" C c a t -T pi „; L3 « cd " -5 -5 -5 § -5 P, 1" oooooom (ONO'O'^'tO ■- e S ■" ^ , be Sh c3'S S c3 o o.-"£X £ O O O (X Ph Ph p, cj 112 UNDEKGEOUND WATERS OF SOUTHERN MINNESOTA. O u k, SC o J- ^■5,58 i d i — • i-VS i i' M ^ O *i s 3 si o * .. * <-TkT 3286 S jjJ 6 fc su ..2 ... CM «SO - v. - v S3 S3 ^ S3 Sk,SE i So E*3 S s .2 .S £h >h >h (* ^ S «« S.-i §§ -1 ^ 8J2 SS >>>. ft. nioBicoi as r-H CMCM V> 1- JO" 3 1 — cooo.ac_: §225225? O SCO IS S3 o afiocfao s» e» E SO CM — t t~ CM »o o o ' ~ c sr it - — cr so o Cj CM CM ^ lO CM ^ lO O CM r-< t^S y,^- 3 £ D s3 < . ^ ._ — SO O CM C lO SO X O SO SO —* X C71 so CM^- rH SO * TC t~. Tji M CM CM SO CM CO rH ^P • : c: i- c x t J) •**.-**.** -»~«« NO CM SOf-> f SO SI 5 "3.S. |9 4^ k, a> O MO _; ■all i o fto k. g£3S&£ • 5 i o t- iS-H O CO 4' H CD 2 o ■Si-sjSg :o 5 5 3 5o8 T: s - r -■- l~ , ^.- "55 a o 9 ° S 55 co S ■z. o o o o o o o : : : : : : ■ ^ io -^ t^- oc io o 3 5o S ss oc :n :c2o SffiQ o p o >g ■^ lO C U7 w ■^* sc 5 i> X ~ " = 5 ! ■'*£ S — • i- ' . O CD 03 m ~ S - _ - o o = a g+s+ij.U.iisjJ) C S3 ^: = J2 ■ . CD >> a; . > o 3 ~ c = :■: srs& , . t.SE^ "* ■■ > "S rf S w> w> w, a C--' a j2 -5 ? - - s3 S3 fj >, d u. CCX CO oO CC CO OC CO CO i~ f H PUBLIC WATER SUPPLIES. 113 V> Vj Vj oSopo • *: o o o o o cqiooo -* -r ,-h -r -^ 2 o o o 4< Z ■o "o -o ij 2 : : :oc £ o *- £ £ "o .is £ - »0 'D LT7 * O 4 § tp -r eo -t i I a> 41 O o a « « > >>> iaj.B ■ ■ ■ a* a- £T~ >_; ™ ^ £3 .— .S .— -S o o >-. ~ '_-_'_ 60920°— wsp 256—11 8 114 UNDERGROUND WATERS 0\- SOUTHERN MINNESOTA. CITIES AND VILLAGES EQUIPPED WITH PUBLIC WATERWORKS. The foregoing tabic includes all public waterworks (as far as known) that have pressure mains, anil also a few where no mains have been laid, the system furnishing a very limited service. It does not, however,, include villages provided merely with lire engine ami hose and an adequate source from which to pump, although their tire protection may be comparably good, DeGrnfV, Holland, N erst rand, Shakopee, Trosky, and Wabasso arc examples of this class. As is shown in a tabic below, nearly all the larger settlements ami many that are still very small are equipped witli systems of water- works. It will be seen that the list includes three-fourths o( the villages having a population between 500 ami 1,000 and one-half of those having between 250 and 500, as well as eight progressive hamlets whose population is still less. In all but five or six eases the waterworks are owned ami operated by the municipalities. Indeed, the great majority of the settlements are too small to attract private capital for such an enterprise. Number of cities and villages in southern Minnesota with public waterworks. Population. With water- works. Without water- works. Tor icnt with water- works. l ,ow or mora 50 .M S 127 ITS 4 IS 95 500 to 1,000 74 250 to 500 50 22 74 85 71 ISO USES OF PUBLIC WATERWORKS. The manifold and varied uses made of the water from public supplies may be grouped as follows: Public use: Fire protection. Public building;?- schools, etc. Sprinkling streets, irrigating parks?, etc. Domestic use: Prinking and cooking. Toilet and laundry. Disposal of sewage. Irrigation and sprinkling. Live stock. Industrial use: Poilor supplies, ote. In nearly all the smaller municipalities protection against tire is regarded as the primary function of a system of waterworks, all other uses being considered incidental and of minor importance. Indeed, experience lias proved that almost without exception, even in the smallest villages, the money expended in this way is saved PUBLIC WATER SUPPLIES. 115 to the community before many years elapse, in the immunity from disastrous fires which is thus afforded. That the value of the public supply for domestic use; is not popu- larly appreciated is clearly proved by the data presented in the table below. As will be shown later, the waterworks have, as a rule, been efficiently equipped at considerable cost and are usually pro- vided with pure water. Considering only the municipalities in which waterworks have been installed, in nearly one-third of those having less than a thousand inhabitants the public supply remains virtually unused for domestic purposes, in less than one-fourth it is used by 50 per cent of the population, and altogether it is used by only 25 per cent of the people residing in these villages. This failure to utilize the public supplies where they are available can be traced to several causes, the principal ones being as follows: (1) The fact that fire protection was the end in view when the waterworks were installed, and that the people are to a great extent oblivious to the other advantages brought within their reach; (2) a persistent but unwise prejudice in favor of private wells; and (3) the expense involved in making service connections and in paying for the water itself. The extent to which the public- supply is used by the people increases with the size of the settlements. Thus in the cities and villages having a population of more than 1,000, excluding Minneapolis and St. Paul, it is used by about 44 per cent of the inhabitants, while in the two large cities the great majority depend at least partly upon the public supplies. The industrial applications of the public water likewise increases with the population. The principal requirement of this character in many of the smaller towns is for the railway locomotives, which at numerous points are provided from the public supply. In the larger centers, however, the demands for water in various com- mercial operations are much more extensive, and the dependence of industry upon the public supply has become an important matter. Number of cities and villages in -which specified percentages of people use the public water supplies provided. Percentage of people using the public supply. Cities and villages with more than 1,000 inhabit- ants. « Number. Per cent of total. Villages with less than 1,000 inhabit- ants. Number. Per cent of total. 90 to 100 per cent. . . SO to 90 per cent 25 to 50 per cent 5 to 25 per cent Less than 5 per cent 5.7 42.9 31.4 14.3 5.7 6.6 17.0 18.0 29.2 29.2 100. 100. a Excluding Minneapolis and St. Paul. 116 UNDERGROUND WATEKS OF SOUTHERN MINNESOTA. SOURCES OF SUPPLY. In selecting a public water supply the principal features that require attention are the following: (1) The quantity of water available, (2) the quality of the water, and (3) the cost. Quantity. — In estimating the quantity that can be drawn from any proposed source it is not usually sufficient to know the normal or average amount. Where only limited storage facilities are pro- vided, calculations should rather be based upon the minimum pro- duction — the supply afforded in the most protracted periods of drought. Likewise it is not safe to base estimates upon the average consumption. There will be times when much more than the ordi- nary amount of water will be used, and unless the supply is adequate to meet these unusual demands, much inconvenience will result. Moreover the seasons of minimum supply and maximum demand are likely to coincide. Finally, it is important to take into account the probable increase in population and industrial development, and to provide for the enlarged needs at least of the immediate future. Quality. — The quality of the water should be considered with reference to its sanitary character, agreeability, and mineral com- position. The numerous causes of pollution which exist in cities and villages render it relatively difficult and expensive to obtain water supplies that are removed from all danger of contamination. As will be shown later, a large proportion of the private wells in cities and villages are polluted, and it is therefore especially important that the public waterworks should be provided from a source that is carefully safeguarded. The agreeability of the water refers to those properties which render it pleasant or offensive to the senses; that is, its appearance, odor, taste, temperature, etc., without reference to its effect upon the health. An illustration is afforded by the " irony" water, so abundant in southern Minnesota. The iron in solution gives this water a characteristic taste, and upon precipitation renders it turbid. The water may be entirely whole- some, but the people frequently refuse to use it, and any supply that the people reject is a failure. Indeed, the popular preference for private wells and the prevalent disinclination to use the public water for drinking and culinary purposes is in large measure due to the fact that for the public supply agreeability is ignored and the water is not rendered attractive to the consumers. The mineral quality of the water has already been exhaustively discussed in a preceding chapter. For fire extinction, flushing of sewers, sprinkling of streets, etc., the quality of the water is of no consequence; for drinking and cooking the sanitary character and agreeability are important; while for bathing and laundry purposes, and for boiler and most other PUBLIC WATER SUPPLIES. 117 industrial uses, the mineral properties are important, as soft a water as possible usually being required. The mineral content is also a consideration for drinking and cooking purposes, and, less frequently in this area, for irrigation. Cost. — The cost includes (1) the original outlay for the well or other source and (2) the cost of operation. While there should be no hesitation in making the expenditures necessary to secure a source that is satisfactory both in quantity and quality, yet there has undoubtedly been too great a willingness on the part of many of the communities of this section to spend large sums of money in drilling deep wells where adequate and safe supplies could have been obtained at much less cost, and where the benefits expected to accure from the deep drilling were not of an essential character justifying the great expenditure even if they had been assured. Too often, especially in small municipalities where competent engineering advice is not employed, the cost of operation is not given sufficient weight when plans for installing a public supply are considered. The cost of pump- ing the water is an important matter, as it may be the determining factor in the use of the system by the public. Surface sources. — If a settlement is located near a river or lake, surface water can in most cases be obtained with less original cost and less expense for pumping than underground water. Moreover, there is ordinarily no limit to the quantity available, and it usually has the advantage of being softer and better adapted for bathing, laundry, and boiler purposes than underground water. On the other hand, it is more subject to pollution, and small communities do not find it feasible effectively to guard the source or to install and main- tain an efficient filter or other means of purification: A river is liable to be polluted by settlements upstream, while a lake may become locally contaminated by the sewage and wash from the settlement concerned. But, aside from the real merits of the case, a practical difficulty is the fact that the popular reluctance to use a public supply is much greater where surface water is drawn upon. Underground sources. — In regard to underground supplies there are a number of difficulties and disadvantages, those most commonly experienced being the following: The yield may be insufficient or not permanent; the expense of lifting the water to the surface may be great; the water may contain organic impurities; or it may be highly mineralized. In southern Minnesota the last-named diffi- culty is the most general and perhaps the most serious. Underground water derived from shallow sources may be impure. Open wells sunk into surficial deposits should be relied upon as safe only if their environs are protected from pollution. On the other hand, water from deep horizons is almost invariably free of organic 118 UNDERGROUND WATERS OP SOUTHERN MINNESOTA. impurity at its source, but, as has been shown by comparative chem- ical and bacteriological analyses, it frequently does not possess the same quality when it reaches the consumers. This is because of pollution at the well or in the reservoirs or other parts of the S3 r stem. The remedy for this condition is theoretically simple: If all parts of the system are kept tight the introduction of shallow water or sewage will be prevented, and the water will be delivered at the tap uncon- taminated. The introduction of organic matter may occur in any of the follow- ing ways: (1) Surface water may pass downward on the outside of the well casing and mingle with the deep water. Where there is a thin overlying impervious layer or none and the casing extends only a short distance down, there is perhaps considerable danger of pol- lution in this manner; but where there is an impervious bed of reason- able thickness and the casing projects well below the level to which the deep water rises, this cause of contamination can not be conceived to be common. (2) The casing may leak. If a suction pump is used (the well casing acting also as the pump pipe) water at or near the surface may be drawn into the system; otherwise it may flow in more slowly. (3) The casing may extend only up to the bottom of the manhole or "pit" of the well, and the leakage from the pump together with ground water and surface wash may enter the manhole and flow into the well. A large proportion of the drilled wells used for public supplies in southern Minnesota are intentionally so finished that they serve also as drains for the waste water — an arrangement that deserves condemnation. A better method is to dispense with the manhole altogether and to brmg the casing above the surface of the ground. (4) Water is sometimes conducted by gravity from the source to a reservoir, especially where springs at some distance from the settlement are utilized. Since there is no pressure in the pipes or mains in such a system, surface water or sew- age may enter where leaks occur. If the water in the pipes is under constant pressure there is no danger of pollution, since any opening will then allow water to escape but will not permit anything to enter. (5) Reservoirs sunk into the ground are seldom entirely waterproof, and where they are employed, contaminating agencies should be kept at a distance. Moreover the reservoir should have its top built well above the ground and should be kept as nearly filled as possible, so that the pressure will be outward and polluting liquids will get no opportunity to enter. In no case should the water be stored in cis- terns placed under the pump house. It is obvious that there is no advantage in having a deep-water supply if the water is allowed to be exposed to contamination anywhere in its journey from the source to the consumer's tap. However, as has already been said, the PUBLIC WATER SUPPLIES. 119 principles involved in preventing pollution are for the most part simple, and consist substantially in the application of common sense all along the line. Data for southern Minnesota. — The following table shows the sources from which the public waterworks in southern Minnesota are supplied : Sources of public water supplies in southern Minnesota. Source. Number. Per cent. Wells 162 8 7 6 3 87 4 4 3 2 186 100 About 91 per cent of the waterworks are provided with under- ground water; about 67 per cent, or approximately two-thirds, from drilled wells more than 100 feet deep. Although small glacial lakes are remarkably numerous throughout most of this region, they are utilized by only a few communities as a source for public supplies. Of the few villages which use surface water, in perhaps the majority the supply is intended for fire protection only (for example, Silver Lake and New London) ; while in several others it is utilized because a satisfactory underground source is wanting (for example, Granite Falls and Cottonwood) ; in only a very few is the water used exten- sively for drinking and cooking. The following table shows the geologic sources of the underground water used for public supplies. Where the water is drawn from different sources, only the principal one is considered; supplies whose geologic source is in doubt are omitted from the tabulation. Sources of underground water used for public supplies in southern Minnesota. Source. Number. Per cent. Alluvium and outwash deposits Glacial drift Total surface deposits Cretaceous system Platteville, Galena, and higher Paleozoic formations St. Peter sandstone Shakopee dolomite, New Richmond sandstone, and Oneota dolomite Jordan sandstone Dresbach sandstone and underlying shales Total Paleozoic Sioux quartzite 16 10 60 39 76 49 9 6 14 9 13 8 5 3 IS 10 19 12 66 42 4 3 100 120 UNDERGROUND WATERS OP SOUTHERN MINNESOTA. Air !_,_ pump I -Natural head Water Air -Air METHODS OF LIFTING WATER. The type of pump employed for bringing water to the surface depends to a great extent on the depth from which it must be raised. If the lift is less than the height of a water column that will balance the pressure of the atmosphere, the pump can be stationed at the surface and the water can be raised by means of a suction pipe let into the well; but if the water stands at a lower level, the pump must be let down into the well. The cost of pumping is much less where the water rises near enough to the surface to make it possible to pump by suction. Deep-well pumps are necessarily limited in their capacity, are expensive to keep in repair, and work at a me- chanical disadvantage. However, where the water stands low in the wells or is lowered very much by pumping, this is usually the only feasible way of lifting it. A third method which is employed at several places, but has not yet come into general use, is known as the air lift. This is a very simple device. An iron pipe is placed in the well, extending from the top nearly to the bot- tom. Air is driven down the pipe. Escap- ing near the bottom of the well far below the water level, the air displaces the water and lessens the weight of the water column sufficiently so that the water will rise and discharge from the well (fig. 9). This method is not limited absolutely by the depth to the water, but it is most successful where the water rises nearly to the surface. The following table shows the various methods used in southern Minnesota : Methods of lifting water to the surface in public veils. Deep-well pumps 79 Suction pumps 37 Natural flow 17 Air lifts 5 Deep-well and suction pumps 1 Deep-well pumps and natural flow 1 Deep-well pump and air lift 1 Suction pump and air lift 1 Suction pumps and natural flow 6 148 Much interest is being manifested in the air lift, and it seems probable that it could be advantageously used in some wells where pumps are at present employed. For these reasons the data in re- gard to the air lifts now installed are given in the following table: -fc-^-'S-VVater Figure 9. — Diagram showing the principle of the air lift. PUBLIC WATER SUPPLIES. Data in regard to air lifts in public water wells. 121 City or village. Blue Earth . Boyd Brownton . . New Prague Pipestone... Sleepy Eye. Waseca Depth of well. Feet. 672 62 304 289 200 350 222 600 1,157 Depth of water in well. Feet. 640 54 280 173 104 254 177 475 1,032 Ratio. 0.95 .87 .92 .60 .52 .73 Yield per minute. Gallons. 350 25 to 50 140 100 100 POWER. The following table shows the different methods of generating power at the various pumping stations: Power used at public pumping stations in southern Minnesota. Over 1,000 Less than inhabit- 1,000 in- ants. habitants. 9 75 44 11 4 1 1 1 1 3 5 62 93 Total. Internal combustion engines (gasoline and gas) Steam engines Electric motors Windmills Water power Artesian pressure Combinations Total reported The great convenience of gasoline engines in the pumping stations of the smaller villages is obvious, and the table shows how largely this relatively new device for applying energy is being employed. In most of the cities and larger villages, where more expensive ma- chinery has been installed and where more pow r er is required and longer hours of pumping are necessary, the steam engine has for the most part been retained. Water power is used (directly or indirectly) at three pumping stations, windmills in three, and an hydraulic ram in one. Where windmills, hydraulic ram, or artesian pressure are employed, there is usually an arrangement by which gasoline or steam engines can be used in case of fire or other emergency. STORAGE AND DISTRIBUTION. In order to make the water available it is essential that it be forced to all parts of the system of mains and branch pipes. For ordinary purposes it is only necessary to have sufficient pressure to deliver the water readily from the taps at the highest elevations at which it is to be used, but in case of fire the system is not effective unless the pressure is great enough to project the water forcibly for some 122 UNDERGROUND WATERS OP SOUTHERN MINNESOTA. distance so that it can be lodged in quantity in the heart of the flames and at other inaccessible points. The following table shows the different methods employed in southern Minnesota for applying both the domestic and fire pressures: Number of public water systems using specified methods of applying pressure. Gravity o Direct from pump Compressed air Direct from source (natural head ) . No pressure Total reported . a Hydrostatic pressure from a standpipe, a tanlc mounted upon a tower, or a reservoir situated on ele- vated ground. ' Closely related to the question of pressure is that of storage. There are several principal reasons for storing water. It is frequently a matter of economy. Where the consumption is small, the supply for one or more days can be pumped in a few hours, and by stor- ing it at an elevation or under compressed air a nearly constant pressure can be maintained without further attention. In many cases storage is required in order to provide adequate protection against fire, for unless the rate at which the source and pumps can furnish water is equal to the rate at which the water will be used in case of fire it is necessary to maintain a reserve supply. It is evi- dent that these reasons for storing water apply to small villages rather than to large cities. Where the normal consumption is great it ni&j become economical to keep the plant in continuous operation and to pump directly from the source into the mains, thus exerting direct pressure and dispensing with all reservoirs. Moreover, the capacity of the source and pumps is necessarily so great that extra demands in case of fire can easily be met. There are many possible combinations for storage and distribu- tion, each of which has certain advantages and disadvantages. The particular combination best adapted for any given municipality depends upon the conditions to be met, involving a large number of intricately interdependent factors. For fire protection it is necessary to have (1) a strong pressure, (2) a sure pressure, and (3) an ample reserve of water. It is impor- tant at this point to emphasize the fact, too often overlooked, that in small settlements where fires are infrequent and where it is not feasible to support a well-disciplined fire department, the weak feature in the system, as far as fire protection is concerned, most commonly consists in not providing for a pressure that can be depended on. Where reliance is placed upon machinery not in operation every day or at least every week, or upon the concerted PUBLIC WATER SUPPLIES. 123 action of men not constantly working together, the fire protection is very much poorer than it appears to be. In villages the protection is good in proportion as the human element in the system is elimi- nated. In most of the large cities where the system is extensive the domestic pressure is kept constant and relatively low, while special pressure is obtained in case of fire by the use of portable fire engines; but in smaller cities better results are invariably secured by applying the pressure to the entire system by means of the pumps at the pumping station, the pressure thus being obtained more promptly and certainly; and in the villages gravity pressure is found to be the surest. Any system employing compressed air or direct pumping relies upon the working of an engine and pump (in a vil- lage generally a gasoline engine), and since it is impossible to have as good machinery or as well- trained engineers in a village as in a city, the danger of a breakdown at the critical moment is much greater, and experience has shown that it is not uncommon for the engine to refuse to work at the very time when it is most needed. A good arrangement adopted in many villages is to have gravity pressure which can be reinforced by direct pumping. Underground reservoirs are liable to pollution, and where storage is required it is therefore desirable to employ either compression chambers or reservoirs so high as to be above the reach of contam- ination by sewage. Mechanical considerations frequently require reservoirs at or near the surface. Thus where deep-well pumps must be used it is often advantageous to allow these to discharge into surface reservoirs, and to utilize duplex or triplex force pumps for raising the water higher, rather than to compel the deep-well pumps to make the entire lift; also where air lifts are installed it is generally necessary to have a surface reservoir into which the water may be discharged; but in such cases it may be advisable to build the reservoir just above the surface rather than to sink it into the ground. CONSUMPTION OF WATER. The following table gives approximately the amount of public water consumed in southern Minnesota: Consumption of water from public supplies in southern Minnesota. Total daily consumption. Total num- ber of people supplied. Average daily con- sumption per capita. Gallons.- 17,591,854 • 10,781,044 8,911,000 695,000 "261,974 a 197,023 106,490 16,221 Gallons. 67 St. Paul : 55 Other cities and villages with more than 1,000 inhabitants 84 43 37,978,898 581,708 65 a The total population according to the 1905 census is here given. 124 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. It should be understood that the above figures generally represent only rude estimates and include certain vitiating factors which destroy their value for drawing refined inferences. The daily per capita con- sumption is derived by dividing the total daily consumption by the number of people supplied; but this gives a result uniformly too high, since under ' ' total consumption " are included the water used for industrial and public purposes and also that lost through leakage — a by no means inconsiderable amount. It is not easy to allow even approximately for the last-named items. Although industrial con- sumption increases with the population, the proportion of people in the smaller communities using the public supply is so low, and in so many places large amounts of water are sold to the railway companies for use in locomotives, that it is not at all evident that the per capita allowance should be greater in the large than in the small municipalities. The per capita estimates for Minneapolis and St. Paul are rendered relatively too low by the fact that they are based upon the total population. From a general consideration of the subject it seems safe to say that, on an average, village inhab- itants (those provided with public supplies) consume less water than the residents of cities; and it is believed that the chief explanation of this difference is that the latter have better facilities for applying water to useful purposes (bathrooms, sewage disposal, irrigating lawns, etc.) than the former, and moreover have learned to use these facilities more liberally. PRICE CHARGED. The following table shows the methods of charging for water, in so far as they have been reported : Number of cities and villages using specified methods of charging for water. Flat rates 55 Meter rates 34 Both flat and meter rates 31 Free 3 Total number reporting price 123 The method of installing meters and charging for the water actu- ally used is found to be much more satisfactory than that of collecting a fixed (or flat) rate per annum. By the latter method a small proportion of the consumers frequently waste more than is used by all of the rest of the community. The relative prevalence of different minimum flat rates (including the minimum charge where meters are used) is shown below. In most towns meter rates are arranged according to a sliding scale, the larger consumer getting a better rate than the person using only a small quantity of water. PUBLIC WATER SUPPLIES. 125 Number of cities and villages having specified minimum annual flat rates (including minimum charges where meters are used). Free 3 $2 1 $3 10 $3.75 1 $4 13 $4.50 1 $4.75 2 $5 36 $5 .40 1 $6 19 $8 1 $9 1 $12 : 2 $18 1 In the following statement the relative prevalence of different maximum meter rates is shown. The maximum rates represent most closely the price paid for domestic consumption. The average maximum rate is 33 cents per 1,000 gallons. Number of cities and villages having specified maximum meter rates per 1,000 gallons. 8 cents 1 10 cents 1 12 cents 1 13 cents 1 14 cents 1 15 cents 1 20 cents 8 25 cents 11 27 cents 3 30 cents 7 33 cents 1 35 cents 1 40 cents 12 45 cents 1 47 cents 2 50 cents 7 53 cents 1 56 cents " 1 80 cents 2 $1 1 Although in most instances the price is not high, it appears for- midable to many village inhabitants who have always been accus- tomed to think of water as a commodity that nature furnishes free to all, and with many of the people this is the real barrier to the use of the public supply. In a large proportion of the smaller vil- lages so little use is made of the waterworks that the resulting reve- nue is almost negligible. These communities have already gone to great expense to install the system, and they are paying a 126 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. considerable sum each year for maintenance and operation. The additional cost involved in furnishing the domestic supplies for all the people wonld not he great. In view of these Pacts it is pertinent to raise the question whether it would not be good public policy for municipalities of this class to furnish water for domestic pur- poses free of charge anil (o pay for the maintenance ami operation of the waterworks wholly by taxation. The conditions at Ilanley Falls, described in the report on Yellow Medicine County, are instruc- tive in this connection. In this village the water is supplied free and is used by all the people. There is no extra expense for serv- ices, since the village marshal attends to the pumping, as the usage is in many other villages. Almost the only additional cost is for gasoline to run the engine, and this is nearly negligible. The daily per capita consumption is only about 30 gallons, which fact shows that there is little disposition on the part of the people to abuse their privilege. Indeed, the total consumption is not much greater than in some villages where the supply is almost unused for domestic purposes, but where the water is wantonly squandered at a few taps for which a flat rate of only a few dollars is annually paid. THE SANITARY PROBLEM. The domestic water supply for a great majority of the village inhabitants of southern Minnesota is derived from shallow, open wells, a situation resulting from the geologic conditions already described. Since few villages have sewers, these wells are necessa- rily near one or more privies or cesspools. In order to ascertain to what extent they are affected by these sources of pollution, water was analyzed from eleven private dug or bored wells situated in as many different villages. These wells are believed to be fairly representa- tive of the most common type in use in the smaller settlements, as care was taken to select only such as were not more exposed to pol- lution than the average. The water of nearly all these wells is used extensively for drinking and cooking. Water from ten of them showed the presence of Bacillus coli, which is considered a conclu- sive evidence of contamination by human or other animal excreta. In the water from the eleventh well the results were uncertain, but there were some indications of B. volt. A brief description of the wells follows : 1. Well about 2 toot in diameter and 40 feet deep, cased with wood. Hotel privy about 30 feet distant. The water is used extensively for drinking and cooking. B. coli found in the water. 2. Well about 2 feet in diameter and 20 feet deep, eased with tile. The surround- ings are clean and tidy. Privy 20 or 25 feet distant. The water is used for drinking and cooking. B. coli present. 3. Well 18 inches in diameter and 50 feet deep, eased with tile. Hotel privy about 50 feet distant. The water is used extensively for drinking ami cooking. B. coli present. PUBLIC WATER SUPPLIES. 127 4. A dug well 37 feet deep, cased with boards. Privy and stable about 50 feet dis- tant. The water is used for drinking and cooking. B. coli present. 5. A bored well of the usual construction and with the usual surroundings. Water used extensively for drinking and cooking. B. coli present. 6. Well 2 feet in diameter and about 30 feet deep, cased with wood. There is a privy 75 feet distant. The water is used for drinking and cooking. B. coli present. 7. Well 2 feet in diameter and 25 feet deep, cased with glazed tile. A privy is 50 feet from the well. B. coli present. 8. Well 2\ feet in diameter and 35 feet deep, cased with wood. Privy is 40 feet dis- tant. The water is used for domestic purposes. B. coli present. 9. A shallow, private bored well' of usual construction and surroundings. Used exten- sively for drinking and cooking. B. coli present. 10. Well about 3 feet in diameter and 30 feet deep, cased with brick. The surround- ings are clean and tidy. Privy 80 feet distant on lower ground. Dwellings near by on higher ground. Water used for drinking and cooking. B. coli present. 11. Well 2 feet in diameter and 22 feet deep, cased with wood. The casing is in good condition, and the ground is graded up around the well. Two privies at distances of about 80 and 100 feet, respectively. Stable nearer the well. Water used for domestic purposes. The results of the analysis were not con- clusive, but there were some indications of B. coli. It can not be affirmed that the bacillus is in all cases derived from the environing privies; in some instances it may be washed into the well with the fasces of domestic animals, or it may be introduced in other conceivable ways. Neither is it intended here to imply that all this water is dangerous to health. Nevertheless it must be admitted by everyone that the situation is far from satisfactory from either a sanitary or an esthetic point of view. In conclusion, it is desired to make a plea for higher ideals of cleanliness and sanitation in the villages of southern Minnesota. Either a system of waterworks or a system of sewers is incomplete in itself. Every community should aim to procure an adequate and safe source of water supply, to install an efficient system of waterworks with mains reaching as nearly as possible to every home, and to construct an approved and extensive system of sewers. The people should then avail themselves of the opportunity afforded, thus securing pure water for drinking and cooking, an abundant and convenient supply for toilet and laundry purposes, and an effective, cleanly, and sanitary method of disposing of sewage and waste water. It is commonly objected that such a system of waterworks and sewers would be financially ruinous to an ordinary village, but this need not be so if it is rightly planned in the beginning. A common difficulty is that too much is expended upon makeshifts. A source is obtained which is unsatisfactory or inadequate; a tank that is too small is erected upon a tower that is too low; mains are laid which are too small or are inferior in quality; and if a sewer is con- structed it is improperly built or not laid deep enough to make its 128 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. extension feasible. The result is that money must constantly be spent for reconstructing defective parts, and no progress can be made in extending the system. Every village, when it first takes up the problem^ should, with the aid of expert engineering advice, plan a complete system that will be satisfactory and adequate for the present and for a considerable time to come. The essential portions of the system should first be provided, and future expenditures can then be applied to extension rather than to remodeling. In progress toward ideal conditions the main reliance must be placed in the education of the people in the elementary principles of sanitation. When once they comprehend that in drinking the "clear, cold" water from their shallow private wells they are imbib- ing the bacteria-laden seepage from their privies or barnyards, and when, furthermore, they understand that better conditions are within their reach, they will be ready to do their part in the work of improvement. DESCRIPTIONS BY COUNTIES. ANOKA COUNTY. By C. W. Hall and M. L. Fuller. SURFACE FEATURES. The upland surface of Anoka County is comparatively low, aver- aging but little over 900 feet above sea level and only about 100 feet above Mississippi River. In general it is flat or gently undulating, with many broad shallow sags occupied by swamps or lakes, but in the extreme northwest it consists of morainic hills. The streams occupy shallow valleys which do not affect to any extent the general character of the country. Everywhere the surface of the county indicates a recent origin. It has been modified but little since the glaciers withdrew from it. r SURFACE DEPOSITS. The glacial drift has considerable thickness, but is exposed at the surface chiefly along the southeastern edge and in several small areas on the western border of the county; elsewhere it is covered by out- wash deposits. It is prevailingly clayey, but in places is sandy and may include layers of clear sand or gravel which contain considera- ble amounts of water but do not yield it as generously as the sand- stones beneath the drift. The red clay was doubtless derived from the Lake Superior region, its color being due to the decomposition of the basic eruptive rocks; the blue clay, which overlies the red, was deposited in part by glaciers from the northwest, and is derived, in large part at least, from the Ordovician and Cretaceous shales. ANOKA COUNTY. 129 The outwash deposits consist of gravel and sand 20 to 50 feet thick, laid down by streams issuing from the melting ice sheet and flowing over the flat upland surface. The materials thus deposited cover by far the greater part of the surface of Anoka County, being absent in only a few narrow strips along the eastern and western edges. Be- cause of their open and porous character they readily absorb the rain falling on their surface. Hence they are saturated wherever they lie below drainage level, and will usually yield supplies adequate for domestic and farm purposes. Alluvial deposits are limited to narrow strips along Mississippi and Rum rivers and several smaller streams. They generally con- tain water and afford supplies to many private wells. In Grow Township, north of Anoka, dunes are prominently devel- oped, forming hills of very clean sand 10 to 30 feet in height. They readily absorb the rain falling on them, but because of their exposed position are of little consequence as a source of water supply. ROCK FORMATIONS. The Platteville limestone is represented in this county only by the basal 25 feet or more found in a few small areas in the extreme south- ern portion of the county. Below the Platteville is the St. Peter sandstone, which extends over much of the southern half of the county. Because of the thick- ness of the overlying drift and the abundance of water that it usually contains, very few wells have been sunk into the St. Peter, but wells drilled at Centerville penetrate it, finding rather large supplies. Locally water from this formation is under considerable head and rises nearly or quite to the surface. Next below the St. Peter lies the Prairie du Chien group, consisting, in succession, of the Shakopee dolomite, New Richmond sandstone, and Oneota dolomite. The Shakopee is probably about 35 feet thick. The exact position of the area in which it lies immediately beneath the drift has not been definitely determined, but it is known to extend in the southern part of the county from the east edge westward and southwestward, crossing Mississippi River near Anoka. The New Richmond is a thin bed, but carries considerable water and will afford satisfactory supplies to private wells. The Oneota extends across the county probably from near the northeast corner to the river, a little west of Anoka. It is compact and contains little water. The Jordan sandstone, which is next beneath the Oneota, under- lies a considerable area of the county and is a strong water-bearing formation. Below the Jordan are the St. Lawrence formation, the Dresbach sandstone and underlying shales, and the red clastic series, the latter resting upon granite. The St. Lawrence formation, characterized 60920°— wsp 256—11 9 130 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. by considerable green sand with green shale partings, probably under- lies the county throughout practically its whole extent, although it has been reached by wells in but few localities. The Dresbach sand- stone and underlying shales underlie all of Anoka County and make a strong water zone. At Elk River, less than 3 miles east of this county, the red clastic series has been penetrated to a depth of 215 feet. Granite was encountered at St. Francis at the depth of 550 feet, and outcrops are found only 20 miles from the northern border of the county. At several points in the vicinity of Center ville Lake, wells have been sunk for the city of St. Paul. Below is given the record of one of these wells which at the surface is 883 feet above sea level and ends at about 404 feet above sea level. Section of well near Centerville Ldke. a Thick- ness. Depth. Glacial drift: Black muck Blue clay Sandy clay "Hard pan " Sand and gravel Clay St. Peter: Sandstone (remnant) Shakopee: Magnesian limestone New Richmond: Soft sand Oneota: Hard magnesian limestone Jordan: Sandstone St. Lawrence: Green and blue shale (penetrated) . Feet. 4 8 30 10 72 10 12 33 7 127 Feet. 4 12 42 52 124 134 146 179 186 313 400 479 a Fourteenth Ann. Rept. St. Paul Board of Water Commissioners, 1895, p. 134. At Anoka the stratigraphic section begins approximately at the horizon at which the Centerville wells end. The first formation encountered below the surface deposits, which here are 80 feet thick and consist of alluvial and outwash materials and red bowlder clay, is a 40-foot layer of soft blue shale, beneath which there is a series of harder layers, most of which are probably more indurated shales. The old well of the Minnesota Potato Starch Company is 390 feet deep and is reported to have entered a white sandstone to a depth of 30 feet. The new well owned by the same company is 420 feet deep and has penetrated this sandstone somewhat farther. The lower portion of the section revealed by these wells no doubt belongs to the Dresbach sandstone and underlying shales. UNDERGROUND WATER CONDITIONS. Yield of water. — Owing to the fact that a great sheet of out-wash sand and gravel lies at the surface throughout most of the county ANOKA COUNTY. 131 and is underlain by a bed of impervious bowlder clay, the conditions are unusually favorable for obtaining generous and permanent sup- plies of water at shallow depths. For larger supplies the various sandstones described above can be penetrated. The heaviest de- mands upon the underground water are made in the southeastern corner of the county, where on occasions millions of gallons are pumped in one day for the St. Paul public supply. Head of the water. — In the Mississippi Valley above Anoka and also some distance below that city, as well as in the lower portion of the valley of Rum River, the water from the deeper sandstones will rise above the surface, and flowing wells can be obtained. Both of the deep wells of the Minnesota Potato Starch Company at Anoka flow at the surface. In the new well the water will rise about 20 feet above the level of Rum River, or 880 feet above sea level. This well is 8 inches in diameter, and with the top of the casing at approxi- mately 867 feet above sea level the natural flow is about 210 gallons per minute. Advantage has not yet been taken of the artesian con- ditions in the vicinity of Anoka, although they have considerable potential value. More wells should be drilled into the deep sand- stone, and no water should be allowed to run to waste, as this will inevitably deplete the supply and diminish the artesian pressure. On the uplands the water from the sandstones will rise nearly to the surface, but probably no flows can be obtained. In the deep wells at Centerville the water rises virtually to the surface or 883 feet above sea level, and in the deep well of the St. Francis Potato Starch Com- pany, at St. Francis, near the opposite corner of the county, the water also rises within a few feet of the surface. Quality of the water. — The water from the outwash sand and gravel, as well as that from the sandstone formations, is moderately hard, but not excessively mineralized. An analysis of water from each source is given below. SUMMARY AND ANALYSES. Unfailing supplies for farm and domestic purposes can generally be obtained from the porous sand and gravel near the surface. Where larger supplies are required or where a source less exposed to pollut- ing agencies is sought, drilling should be continued to the underlying sandstones. In the valleys and on some of the terraces of the Missis- sippi and its principal tributaries, flowing wells can be obtained from the deeper horizons, and throughout the county the water is under sufficient head to rise nearly to the surface. The only city that has a system of waterworks is Anoka. The plant is owned by a private company and the water is taken from Rum River. 132 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Mineral analyses of water in Anoka Count)/. [Parts per million.] Silica (SiOs) 17 Iron ( Fe) 1.1 Calcium (Ca) 19 Magnesium (Mg) 12 Sodium and potassium (Na+ K) 12 Carbonate radicle (CO3) Bicarbonate radicle (I1C0 3 ) 142 Sulphate radicle (SOi) 2 Chlorine (CI) 1 Nitrate radicle (N0 3 ) Total solids 149 8.8 1.2 65 IS 31 .0 264 20 48 .0 332 1. Spring; at Itasca in outwash gravel. Analysis by C. W. Drew. 2. Tlie new flowing well of the Minnesota Potato Starch Company at Anoka, 420 feet deep, in the Dres- bach sandstone and underlying shales. Analysis made for this Survey December 9, 1907, by 11. A. Whit- taker, chemist Minnesota state board of health. BIGSTONE COUNTY. By O. E. Meinzer. SURFACE FEATURES. The greater part of Bigstone County consists of a nearly level upland plain about 1,100 feet above sea level, abruptly limited on the west and south by a broad, deep valley, incised to a depth of 125 to 150 feet below its surface. This valley, which is now occupied by Lake Traverse, Bigstone Lake, and Minnesota River, originated at a time when the present outlet of Red River of the North was blocked by an ice sheet and its discharge forced southward. The lakes are due to the dams that have been thrown across the valley by the small, swift streams tributary to it. The alluvial fan of Little Minnesota River forms the dam that separates Lake Traverse from Bigstone Lake, and is thus the divide between the Mississippi and Hudson Bay drainage basins. The upland plain is for the most part very poorly drained and abounds in small lakes. Immediately adjacent to the valley there are many short gulleys, but they are of such slight extent that they interrupt the regularity of the upland surface but little. SURFACE DEPOSITS. Description. — The glacial drift consists of bowlder clay and deposits of sand and gravel. The latter are usually interbedded with the bowlder clay, but locally lie at the surface. In the valley the drift and older formations are generally concealed beneath a thin layer of recently deposited alluvium. Considering only the uneroded upland areas, the drift sheet is most attenuated in the southern and in the northwestern and northeast- ern parts of the county, where it is in many places not much over 100 feet thick, and is most developed in the central portion, where it is locally more than 300 feet thick. In the valley, for some miles south from the northern boundary of the county, older formations BIGSTONE COUNTY. 133 are virtually at the surface; and the same is true below Ortonville (PL II). Yield of water. — The sand and gravel beds at various depths in the drift are generally saturated with water, which they deliver to wells at greatly differing rates. In most localities, however, there is at least one bed that will furnish enough for all ordinary purposes. In general it is more difficult to get satisfactory supplies from the drift in the northern than in the southern part of the county, apparently because there are fewer beds of coarse sand. In the region between Odessa and Appleton, and in other sections of the county, the sand and gravel that lies at the surface yields water freely. Head of the water. — Only one flowing well supplied from the drift has been recorded in the county. This well is on the farm of Albert Struck, a short distance northwest of Correll (NE. J sec. 7, T. 121 N., R. 44 W.), and is 186 feet deep. Along the sides of the valley there are numerous springs, all of which are fed by the waters that saturate the drift. Springs of this kind furnish the public supply of Brown Valley and are largely drawn upon at Ortonville. The drainage of the drift waters toward the valley lowers the head beneath the uplands at all points near the valley border. Throughout most of the county the water in the deeper wells remains at some distance below the sur- face, but northward it rises increasingly near the surface, and about 10 miles beyond the county line flowing wells are obtained. Quality of the water. — None of the water from the glacial drift is soft, and some of it is extremely hard and very highly mineralized. The analyses in the accompanying table seem to show that water from the upper portion is apt to be harder than that from the deeper beds, and also that it is generally harder in the northern than in the south- ern part of the county. However, the water from the sand and gravel deposits at the surface may contain only moderate amounts of min- eral matter in solution. CRETACEOUS SYSTEM. Description. — The Cretaceous rocks consist of soft blue shale ("soapstone") and interbedded sandstone strata. A small shale outcrop occurs in the valley near the north end of Bigstone Lake (sec. 23, T. 124 N., R. 49 W.), and another has been described by N. H. Winchell on the Dakota side nearly opposite the northwestern corner of this county. a For some miles along the valley these shales he near the surface, but no other exposures have yet been observed. The well sections shown in Plate VII illustrate the character of the Cretaceous rocks in this region. They have considerable thickness in the northwestern part of the county, but thin out toward the east a Second Ann. Rept. Geol. and Nat. Hist. Survey Minnesota, 1873, p. 190. 134 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. and especially toward the southeast, a condition resulting in part from the irregularities of their upper surface, but chiefly from the inclination of the granitic surface upon which they rest. Altitude of granitic surface and thickness of overlying Cretaceous rocks, Bigstone County. Locality. Brown Valley. . Graeeville East of Johnson Dumont Ortonville Appleton Altitude of top of Cretaceous rocks above sea level. Thickness of Cretaceous rocks. Feet. Feet. 980 440 830 200 900 50 875 35 Yield of water. — Sandstone strata usually produce liberal supplies of water. An example is the new village well at Graeeville, which has been pumped for 48 hours continuously at the rate of 60 gallons per minute. But in a large portion of the county, especially in the eastern and southern parts where the series is thin, there is nothing but shale, and no water-bearing beds are found. Head of the water. — In the valley, from the northern boundary of the county for some miles southward, the Cretaceous sandstone gives rise to flowing wells. Both of the deep village wells at Brown Valley overflow at the surface, the upper of the two at 1,014 feet above sea level. There is also a flowing well 6 miles south of this village (sec. 25, T. 124 N., R. 49 W.), but it has not been determined how much farther down the valley flows could be secured. At Graeeville the Cretaceous water rises to a level about 70 feet below the surface or 1,040 feet above the sea, and at Dumont, 10 miles north, it is lifted virtually to the surface, which is about 1,040 feet above sea level. In Bigstone County flowing wells can be expected only in the valley. Quality of water. — The water from the Cretaceous rocks is soft, in which respect it is radically different from the water of more shallow sources. It is, however, very rich in alkali sulphates and chlorides. Especially is this true at Brown Valley. (See the analyses in the accompanying table and also PL V.) ARCHEAN ROCKS. The Archean system includes several types of crystalline rocks. The drillings from the wells at Brown Valley and Graeeville consist of mica schist, but the rocks exposed near Ortonville are granite and gneiss. The upper portion of the system is usually greatly decom- posed where it is overlain by Cretaceous strata which protected it from glacial erosion. One of the decomposition products especially conspicuous in some localities is a white kaolin. The Archean rocks are reached at different depths down to about 600 feet. They U. S. GEOLOGICAL SURVEY WATER-SUPPLY PAPER 256 PLATE ' Feet above- level Brown Valley Graceville Vicinity of Clinton Dumont - 700- H500-U < Blue shale Yellow clay Blue clay- Sand and gravel Bowlder bed Blue clay Clay and sand - E^^E^Btue shale-r^ — / - Vicinity of Johnson Yellow clay Clay and sand Blue shale ;Sand ( Thin of ~dbi$hT) Decomposed schistose material Blue clay Blue clay Decomposed granitic material / Brownish-blue White sandstone J31ueshale Mica schist ignite sand vrij-j-VJ.Mica schist GEOLOGIC SECTIONS IN NORTHERN BIGSTONE COUNTY. By 0. E. Meinzer. BIGSTONE COUNTY. 135 outcrop at various points in the valley below Ortonville, but nowhere else in the county (PL III), and there is only a small part of the county in which they are less than 300 feet below the surface. In general they are not water bearing, but in rare instances small supplies are derived from the disintegrated upper portion. WATER SUPPLIES FOR CITIES AND VILLAGES. Ortonville. — Ortonville is at the point where Bigstone Lake dis- charges into Minnesota River. Granite lies at no great depth below the valley level, and numerous outcrops occur a short distance from the city. The public supply is taken from a combination dug and drilled well which is about 60 feet deep, ends in a bed of gravel immediately above the granite, and yields several hundred gallons per minute. The water rises within 12 feet of the surface, or 966 feet above sea level. It is used by about 500 people and by the rail- way company and electric-light plant, about 65,000 gallons being consumed daily. Perhaps 75 per cent of the inhabitants depend upon private supplies. On the upland the wells are commonly dug >r drilled through blue bowlder clay to a depth of about 80 feet, at which level there is a recognized layer of water-bearing sand. Many springs issue from the side of the valley, and these are utilized largely for domestic purposes. Graceville. — The public supply at Graceville is derived from two 8-inch wells which tap the Cretaceous sand stratum about 435 feet below the surface. The stratigraphic section is shown in Plate VII. The test of one of the wells was mentioned above (p. 134). The water is soft but rich in the alkalies. An analysis is given in the table (pp. 137-138). Virtually all the people use this supply, and an average of 10,000 gallons is consumed daily. The well at the mill is 440 feet deep, ends in the same sand stratum as the village wells, and also furnishes soft water, which rises to a level 70 feet below the surface, and is yielded freely. Beardsley. — Nearly the entire water supply for the village of Beardsley is derived from a thick bed of outwash gravel at the sur- face. Underlying this deposit there is glacial drift, resting, no doubt, upon a series of Cretaceous shales and sandstones, beneath which lies the granite. The section below the drift is probably similar to that given for Brown Valley. The public supply, which comes from a well 6 feet square and 40 feet deep, is only moderately hard, and is used by about two-thirds of the people, approximately 6,000 gallons being consumed daily. Clinton. — The glacial drift is unusually thick in this locality. Water-bearing beds have been found beneath the village as follows: 1. Gravel at 120 feet. The water is hard and strongly charged with iron. 136 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. 2. Blue clay with layers of fine sand between 125 and 195 feet. The fine sand and hard water will clog and encrust well screens in a short time. 3. Gravel at 195 feet. The water is less strongly charged with iron than that in the 120-foot bed. It rises to about 120 feet below the surface. The 5-inch well of J. L. Erickson, which extends to this horizon, has been tested at 25 gallons per minute. 4. Sand at 240 feet. 5. Gravel at 330 feet. This is penetrated 14 feet by the 8-inch village well, which is finished with a screen and has been pumped for six hours continuously at the rate of SO gallons per minute. The water rises to a level about 120 feet below the surface and is only moder- ately hard, as is shown by the analysis given in the table (pp. 137-138). About SO per cent of the people use the public supply, the remainder depending for the most part upon cisterns, in which they collect rain water. FARM WATER SUPPLIES. The farm supplies in the county are obtained chiefly from the following sources: (1) Drilled wells, (2) bored and dug wells, (3) driven wells, and (4) springs. A large proportion of the wells at the present time are of the drilled type, ranging from 50 to more than 300 feet in depth, but commonly between 100 and 200 feet. Most of the drilled wells are 2 inches in diameter and are finished with screens that become effectually clogged in a few years, but there are also some 5-inch wells, which as a rule do not require screens. SUMMARY AND ANALYSES. Throughout the county the granitic rocks lie within several hun- dred feet of the surface, and since they are essentially nonwater- bearing and there is no water-bearing formation below them, the entire supply must be developed from the overlying formations at limited depths. The first indications that the granitic rocks have been reached in drilling are given by the decomposition products that so commonly mantle the hard rock in this region. These consist of clays of a brilliant red, yellow, or green, or frequently of a nearly white color, and may contain silvery flakes of mica or allied minerals, and angular grains of transparent quartz. Drillers can not fail to notice these striking characteristics, but they are frequently puzzled because they do not understand their meaning. There are two distinct sources of underground water to be drawn upon in the municipal and rural developments in the county — (1) the sand and graA^el beds in the glacial drift and (2) the sandstone strata beneath the shale ("soapstone"). The drift will nearly every- where contribute supplies sufficient for ordinary purposes, but unfor- tunately the water is very hard. The sandstone beneath the shale BIGSTONE COUNTY. 137 yields generously in some places (as Graceville) but is absent in others (as Ortonville), and the localities in which it will prove to be a satisfactory source can be determined only by actual trial, although the chances are best in the northern and western portions of the county. The water is soft, but in some places (as Brown Valley) contains an objectionable amount of alkalies. There are three possi- ble reasons for drilling through the drift and shale to the deeper beds of sand or sandstone — (1) to obtain a sufficiently large supply in a few localities where the yield from the drift is inadequate; (2) to obtain soft water; and (3) to obtain flows, in the valley only, for the water will not rise to the upland level. Mineral analyses of water in Bigstone County. [Analyses in parts per million.] Surface deposits (glacial drift, etc.). Upper portion. South part of county. North part of county Lower portion. Depth feet. . Diameter of well .. .inches. . Silica (Si0 2 ) Iron (Fe) Iron and aluminum oxides (Fe 2 03+Al20 3 ) Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+K) Carbonate radicle (CO3) Bicarbonate radicle (HCO3) . . Sulphate radicle (SO4) Chlorine (CI) Nitrate radicle (NO3) Total solids , 50 50 (a) 28 190 4 31 2.6 251 108 37 12 130 127 464 477 213 320 37 946 97 12 1,132 671 6 224 93 43 424' 650 6 5 1,272 4 366 293 664 1,749 56 2,946 482 243 156 366' 2,143 15 3,277' 4.5 152 116 282 7.4 146 76 413 1,065 15 439 856 17 1,838 1,595 420 502 36 1,165' Depth feet. Diameter of well . . .inches . Silica (Si0 2 ) Iron (Fe) Iron and aluminum oxides (Fe203+Al 2 3 ) Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+K) Carbonate radicle (CO3) Bicarbonate radicle (HCO3) . Sulphate radicle (SO*) Chlorine (CI) Nitrate radicle (NO3) Total solids Cretaceous. Vicinity of Graceville. 440 23" 18 10 351 527' 284 78 1,044 440 8 10 6 17' 9 321 493' 248 65 13 17 11 337 566 252 67 562 256 Vicinity of Dumont (Traverse County). 304 2 5 .4 4 25 10 478 871 535 2, 662' Vicinity of Brown Valley. 480 4.4 17 1,021 400' 1,167 490 2,946' Hi. 520 4.5 17 1,029 400' 1,161 505 2, 959' a Large. 138 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. 1. Well at Ortonville. November 6, 1907. 2. "Hunter's well" at Ortonville. November 24, 1907. 3. Well at Correll. September 19, 1888. 4. Springs which furnish the public supply at Brown Valley (Traverse County). October 5, 1907. 5. Well at Graceville. October 20, 1889. 6. Village well at Dumont. (Traverse County). October 5, 1907. 7. Railway well at Graceville. January 20, 1890. 8. Well at Graceville. September 21, 1895. 9. Village well at Clinton. October 3, 1907. 10. Mill well at Graceville. October 5, 1907. 11. New village well at Graceville. October 5, 1907. 12. Well at Graceville. October 24, 1895. 13. Well at Graceville. September 11, 1895. 14. Well at the hotel at Dumont (Traverse County). October 5, 1907. 15. Lower village artesian well at Brown Valley (Traverse County). October 5, 1907. 16. Upper village artesian well at Brown Valley (Traverse County). October 5, 1907. Analyses 4, 6, 9, 10, 11, 14, 15, and Hi were made for the United States Geological Survey by H. A. Whit- taker, chemist Minnesota state board of health. Analyses 1, 2, 3, 5, 7, 8, 12, and 13 were furnished by G. N Prentiss, chemist Chicago, Milwaukee and St. Paul Railway Company. BLUE EARTH COUNTY. By C. W. Hall and M. L. Fuller. SURFACE FEATURES. The surface of Blue Earth County is that of an elevated plain, the continuity of which is broken at varying intervals by narrow and rather sharp valleys of several tributaries of Minnesota River. The average elevation above sea level is somewhat less than 1,000 feet, which is considerably less than that of the counties to the east and west. The highest points are near the southeastern and southwestern corners, whence the surface slopes gradually northward to the uplands that border the Minnesota and lie about 150 feet above that river. The surface, except for the valleys mentioned, is generally rather flat, but is marked by broad shallow depressions containing lakes or marshes, and at some points near the southern border is somew r hat rolling. A noticeable feature of the valleys is the series of terraces along the larger streams, especially along the Minnesota. The quarry districts north of Mankato and northwest of Minneopa Falls are located on such terraces, while Mankato itself is on a low alluvial terrace. SURFACE DEPOSITS. The alluvium of Blue Earth County is found along the present streams and especially in the valley of Minnesota River. The thick- ness varies, rock projecting through in some places, while in others wells fail to strike rock at considerable depths. Water occurs in rather large quantities, but is given up slowly, owing to the fineness of the deposit. Terrace gravels are simply alluvial deposits of greater age than those now forming. They represent the deposits of glacial and post- glacial streams flowing at levels considerably above the present river. Originally these older deposits extended entirely across the valley of the Minnesota, but later the stream cut through them, leaving only remnants. The gravels and sands are seldom more than 10 to 20 BLUE EARTH COUNTY. 139 feet thick and rest upon shelves cut into the drift or older rocks. Owing to their position in the valleys, they are not important as sources of water supply. The glacial drift is a gray, heterogeneous, pebbly clay, with inter- mingled masses of sand and gravel. Its thickness increases from southeast to northwest, being between 100 and 150 feet at the south- eastern corner and over 200 feet at the northwestern, while in the intervening area it is between 150 and 200 feet, except beneath the stream valleys, where it varies from 25 to 125 feet. A belt of deep drift, apparently representing an old channel either of the Minnesota or one of its tributaries, extends from Mankato beyond Janesville, in Waseca County, the thickness along this tract being 50 to 100 feet greater than on either side. The sandy and gravelly layers of the drift contain water in con- siderable amounts, enough being available in nearly all cases for farm and industrial supplies. The amount of sand, and consequently of available water, generally increases with the depth. A striking and persistent feature of the drift of this and adjacent counties is the yellow layer which covers all older deposits and varies in thickness from approximately 5 to 20 feet. There is frequently present at the bottom of this oxidized zone a water-bearing bed of some economic significance for shallow supplies. CRETACEOUS DEPOSITS (?). Some years ago clay and fine sand, probably derived from Cre- taceous deposits, were excavated near Mankato for the manufacture of fire bricks. They formed a mass of more or less broken and trans- ported material within the glacial drift, and the original bed whence they were derived has not been found. Whether there are other Cretaceous deposits in the county, and whether those deposits are Cretaceous, are questions not yet settled. PALEOZOIC FORMATIONS. Blue Earth County is so deeply covered with drift that no rocks are exposed on the uplands, but along Minnesota River and the lower portions of its tributaries Paleozoic formations outcrop. The Galena and Platteville limestones have not been definitely recognized, but from the fact that they are found in wells a short distance south of this county and also in the deep well at Waseca, 13 miles east, it is probable that they underlie the eastern edge of the county. The St. Peter sandstone is not known to outcrop anywhere in the county, but is penetrated by wells at a number of points along the 140 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. eastern border, where it is about 100 feet thick. It differs from the sands of the glacial drift in its uniformity, its great thickness, and the absence of clay partings. It affords much water for domestic and farm supplies. The rocks of the Prairie du Chien group outcrop along Minnesota River, forming terraces marked by numerous quarries, and occur as a broad subglacial belt across the center of the county. They con- sist essentially of buff and pink dolomite. The presence of a sandy zone corresponding to the New Richmond sandstone is not fully established. The dolomite carries some water in joints and solution passages, especially in its weathered upper surface at the base of the drift, and in a number of wells yields water rising nearly or quite to the surface. Upon the uplands, however, the water must be lifted a considerable distance to bring it to the surface. The Jordan sandstone lies below the alluvium of the Minnesota Valley north of Mankato, and below the drift along a belt stretching from this city to the southwestern corner of the county. It is about 75 feet thick and generally yields supplies sufficient for all purposes. However, on the uplands the water must be lifted a considerable distance. The St. Lawrence formation consists chiefly of shale and mag- nesian limestone and appears to be about 200 feet thick. It outcrops in the Minnesota Valley near Judson and probably extends beneath the drift to the southwestern corner of the county. It carries little water except in occasional sandy layers and near its upper surface. The Dresbach sandstone and underlying shales have not been seen at the surface, but they underlie the drift and the Paleozoics through- out the county. From the record of deep wells at Mankato these beds appear to include about 420 feet of material, mainly sandstone. They are saturated with water and yield large supplies to wells at Mankato, the public waterworks and several large industrial plants depending chiefly on it for their supplies. Beneath the shales that underlie the Dresbach sandstone is a series of red sandstones, shales, and quartzites which has been penetrated nearly 1,300 feet in the Mankato well, but which affords only an insignificant amount of water compared to that yielded by the over- lying formations. Beneath these red sediments is Archean granite, which is likewise virtually not water bearing. WELL RECORDS. Below are given three well sections, two of which extend to Archean rocks, showing a rapid rise of the latter toward the west, with a cor- responding thinning of the stratified series. With such conditions the correlations are necessarily conjectural. BLUE EARTH COUNTY. Section of deep well on Bunker Hill, at Mankato. - 141 Thick- ness. Depth. Glacial drift, etc.: ' Clay, sand, and gravel Paleozoic and lower formations: Limestone, green shale, and sandstone [St. Lawrence] Sandstone and shale [Dresbach sandstone and underlying shale] Red sandstone and shale (entered) ." Feet. 290 205 420 1,289 Feet. 290 495 915 2,204 o Upham, Warren, Final Rept. Geol. and Nat. Hist. Survey Minnesota, vol. 1, 1882, pp. 422-424. The correlations are not by Mr. Upham. Section of well at Minneopa Falls. Thick- ness. Depth. Glacial drift, etc.: Soil, sand, gravel, and weathered limestone Paleozoic and lower formations: Blue shale AVhite sandstone ( J ordan?) "Red claylike stone " ''Blue slate, white when dry' Pink sand AVhite sand (Dresbach?) Red quartzite, conglomerate, etc Dark-gray quartzose sandstone or conglomerate, with some red shale Crystalline rocks (Archean) Feet. 100 10 35 20 100 10 100 200 60 365 Feet. 100 110 145 165 265 275 375 575 635 1,000 Section of village well at Lake Crystal. Thick- ness. Depth. Glacial drift Paleozoic and lower formations: Sandstone (lower part of Jordan ?) Limestone and shale (St. Lawrence) Limestone, shale, and white sandstone (Dresbach sandstone and underlying shale).. Red clastic series Granite (entered) Feet. 145 40 140 324 50 20 Feet. 145 185 325 649 699 719 FLOWING WELLS. In the lower areas of the county there are many flowing wells, some of which are supplied from Paleozoic formations, but the majority of which end in the drift at depths of 50 to 100 feet. A chain of these wells extends along Blue Earth River from the Faribault County border to its confluence with the Minnesota, and others are located along Watonwan, Maple, Little Cobb, and Lesueur rivers, but none are obtained on the upland prairie. WATER SUPPLIES FOR CITIES AND VILLAGES. Mankato. — Within the city of Mankato is to be found a w T ide range of well conditions. Some supplies are obtained from the drift, others from the successive sandstones and limestones, and many from the alluvium lying along the flood plain of Minnesota River. A large 142 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. number of artesian wells have been drilled. For a time all of them yielded generously, but in recent years they have shown signs of decrease in flow, this tendency being greatest in the wells that furnish water with high iron content. When hard deposits, such as iron crusts, travertine layers, etc., form in the well, shooting with dyna- mite will frequently give relief. The observations made upon the data collected at Mankato seem to indicate that more attention can be given with profit to the shallower Paleozoic sources. While the water from these has a lower head, it seems to be somewhat softer than that in the deeper beds. The public supply is obtained from four flowing wells 650 feet deep. About two-thirds of the population use this water, and an average daily consumption of 783,000 gallons is reported. Lake Crystal. — The public supply at Lake Crystal is derived from a well 719 feet in depth, the log of which is given on page 141 . Shal- low wells furnish the supply for a large part of the population, although there are several deeper wells also ending in glacial drift. Mapleton. — The public supply of Mapleton village, which is used by virtually all of the people, is drawn from a 4-inch well 224 feet deep, in which the water rises to about 30 feet below the surface. The deeper wells enter a sandstone which is probably the St. Peter. Patches of limestone have been found overlying the sandstone, indi- cating that the Galena or the Platteville limestone is present in some localities but not in others. Good Thunder. — The public supply at Good Thunder is taken from a well that is 374 feet deep and ends in sandstone. Most of the people use private wells. Amboy. — In Amboy village the public supply is derived from a 6-inch well that extends to a depth of 486 feet and taps a standstone which is probably the Jordan. Fully two-thirds of the people use water from private wells. Vernon Center. — The waterworks are supplied from a well 147 feet deep. The public water is not extensively used. SUMMARY AND ANALYSES. For ordinary purposes the glacial drift usually affords adequate supplies, but, except possibly in the northwestern portion of the county, the deep-lying sandstones will yield still more generously. The three well sections given above show the stratigraphic succession. Although flows are commonly obtained in the valle3 T s from both the drift and the sandstones, they can not be secured on the upland prairie from either source. BROWN COUNTY. 143 Mineral analyses of water in Blue Earth County. [Analyses in parts per million.] St. Peter sand- stone. Jordan sand- stone. Dresbach sandstone and underlying shales. Depth feet. Silica (Si0 2 ) Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+K) Bicarbonate radicle (HCO3) Sulphate radicle (SO4) Chlorine (CI) Total solids 225 17 152 46 78 464 310 4 855 22 170 58 85 455 470 14 1,037 650 9 111 38 64 461 174 8 635 650 6 79 35 44 417 85 4.8 459 650? 65 126 52 25 380 233 20 654 1. Village well at Mapleton. November 15, 1906. 2. Village well at Amboy. November 14, 1906. 3. Well at the Hubbard Mills, No. 1, in Mankato, 1889. 4. City wells at Mankato. 5. Well at the flouring mill in Mankato. Analyses 1 and 2 were made for the United States Geological Survey by Prof. W. S. Hendrixson. Analy- sis 4 was furnished by G. M. Davidson, chemist Chicago and Northwestern Railway Company. Analysis 5 was made by the Kennicott Company. BROWN COUNTY. By O. E. Meinzer. SURFACE FEATURES. The surface of Brown County is a nearly level plain, most of which lies between 1,000 and 1,100 feet above sea level. The southwestern corner, however, is higher and has a more irregular topography, probably being part of the moraine that can be traced northwestward across Yellow Medicine County and in the opposite direction through Martin County into Iowa. a The northeastern boundary is formed by Minnesota River, which occupies a valley 150 to 200 feet deep. Big Cottonwood and Little Cottonwood rivers flow eastward across the county through shallow trenches until they approach the Minnesota, where their grade increases and their valleys are deep and gorgelike. In other words, these valleys are not in topographic adjustment with that of the Minnesota. The latter was excavated rapidly at the close of the last glacial epoch by the abundant waters issuing from the melting ice, while the former are still flowing on the surface of the upland throughout the greater part of their course. The wide inter- stream areas have only a very imperfect and sluggish drainage, and contain numerous swamps, ponds, and lakes. Near the Minnesota Valley the upland is dissected by many deep valleys, which do not, however, exceed a few miles in length. a Upham, Warren, Final Rept. Geol. and Nat. Hist. Survey Minnesota, vol. 1, 1882, p. 581, 144 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. SURFACE DEPOSITS. Description.— The surface deposits include recent alluvium and glacial drift. The former is found only in the valleys of Minnesota River and its tributaries, and is not important; the latter is present everywhere except in small tracts in the valleys of Minnesota and Cottonwood rivers, and in a few other localities where underlying formations are exposed. The entire drift mantle has frequently been pierced in drilling wells. Throughout most of the county it is between 100 and 200 feet thick, but over a restricted section in the eastern part it has a somewhat greater thickness, while in the southwestern corner, where the quartzite occurs, and in the valleys of Minnesota and Cottonwood rivers, where postglacial erosion has taken place, it is generally thinner. The drift consists of unassorted bowlder clay with interbedded deposits of sand and gravel, which are roughly assorted and stratified and comprise the pervious, water-bearing members. Porous, gravelly beds also frequently lie at the base of the drift, and in the southeastern part of the county these attain a remarkable thickness, as is shown by the section of the mill well at Hanska given in Plate XVI. Yield, head, and quality of the water. — The sand and gravel which occurs in the drift or at its base usually yields generous supplies of water. In most of the county the water rises within 50 feet of the surface, but in the deeper wells on the upland prairie near Minnesota River it frequently remains at depths of 100 to 200 feet. Especially is this true in the vicinity of New Ulm. In the valley of Cottonwood River at Springfield there is a small area of flowing wells that are about 30 feet deep and end in a bed of sand beneath a layer of clay. These wells have a head of only a few feet and flow several gallons per minute each. Along the Minnesota and its tributaries there are many springs, one of the largest of which is the "Big Spring," in the Golden Gate vicinity. The water derived from the drift has invariably been found to be hard but otherwise good. (See the analyses in the accompany- ing table, p. 148.) CRETACEOUS DEPOSITS. Description. — Between the drift and the older indurated forma- tions there is a series of beds consisting of layers of clay, shale, marl, sand, sandstone, lignite, etc. The sandstone is generally white, while the clays and shales have various colors but are predominantly red. The fossil leaves, the oxidized condition of the clay, the marked cross-bedding, the lack of continuity of the strata, and the presence of lignite, all indicate that these are either nonmarine or littoral deposits. The fossil leaves determined by Leo Lesquereux and James Hall seem to correlate them with the Dakota sandstone of the U. S. GEOLOGICAL SURVEY WATER-SUPPLY PAPER 256 PLATE VIII Sleepy Eye Feet above sea level Cottonwood River Little Cottonwood River Sigel Twp. Cottonwood Twp. Milford Twp. New Ulm 900 o — fsSE?E£oz Yellow clay" Blue clay Gravel Granite Clay Gravel Clay ( Mb pebbles ) Gravel Clay \(No pebbles) Pebbly day Blue clay -:■<■■ Red and white clay Sandstone Yellow clay Blue clay Red^day Red and white clay Sandstone V Shale Gravel. White clay (Wb pMles) (Corltains one thin stratum of brownish red clay) White clay Turning darker) Red granite Yellow clay Blue clay Sand Blue clay Red day White clay {With $treak* of red and green clay) - Sandstone Yellow day Blue clay — \~ Sand -" Red clay Sandstone Clay, sand, and gravel Sand" Red clay Green clay Sandstone Granite GEOLOGIC SECTIONS IN BROWN COUNTY. By O E. Meinzer. Sleepy Eye. — Generalized section from field notes of M. L. Fuller. Cottonwood lliver. — Well 3 miles southeast of Sleepy Eye, on bank of Cotton- wood River. Reported by N. H. Winchell in Fourteenth Ann. Rept. Geol. and Nat. Hist. Survey Minnesota, i885, p. 15, on authority of 0. M. Phelps, who drilled the well. Little Cottonwood River.— Well on farm of George Helget, NE, ] see. 36, T. 109 N., R. 32 W. Si^el Township.— Well on farm of ,1. Zimmerman, SE. | sec 1!), T. 109 N., R. 31 W Cottonwood Township. — Well on fa II. 30 W.; approximate. i rge Haas, SE, I sec. 6, T. 109 N., Milford Township.— Well on farm of .1. M. Haubrick, SW. \ sec 21. T. 110 N , R. 31 W. This section and the three preceding are Riven on the authority of Fred. Ilamann, driller, New Ulm. New Ulm. — City wells on a terrace about i;> feci above the river. Authority, Charles Stoll and others. The altitudes for all except the lirst and last sections an I) approximately known. BROWN COUNTY. 145 Upper Cretaceous. They are exposed in the Minnesota Valley at New Ulm and for several miles below that city, and .also at various points in the valley of Cottonwood River. They have been pene- trated in numerous wells south of the Cottonwood and in the vicinity of New Ulm (PL VIII). From the data at hand it may be said that the Cretaceous deposits range up to at least 200 feet in thickness, and that they are present throughout most of the southern section of the county except in the southwestern corner, where the quartzite is near the surface. At Sleepy Eye and in much of the northern part they appear to be absent, but in this county they may so far resemble the drift that it is difficult to differentiate them in well sections. The red, green, and white clays or shales, the white sand- stones, and the layers of lignite are at once recognized as Cretaceous, but it is probable that the blue and yellow cl&ys and the sand and gravel which are referred to the drift are in fact partly Cretaceous. If this is true, the thickness of the drift is not everywhere so great as is supposed and a thin layer of Cretaceous material may exist beneath the drift in localities where it has not been recognized as such. Yield of water. — Where Cretaceous sandstones are found they will produce large quantities of water. The three city wells at New Ulm are together pumped at the rate of 350 gallons per minute, and all the Cretaceous farm wells that were reported yield ample supplies. Head of the water. — The water from the sandstones has about the same head as that from the drift. As far as is known, there is no place in the county where they will produce flowing wells. At New Ulm, on the first terrace, the water rises to 75 feet below the surface, which is about 30 feet below the level of the river, or 765 feet above the sea. Near the river it will therefore stand about 200 feet below the level of the upland prairie. According to report, when the first well was sunk into the Cretaceous sandstone at New Ulm, nearly twenty years ago, the water rose 35 feet higher than it does at present. Quality of the water. — Although the sandstone water is not soft, it is generally considered less hard than that from the drift, and it stands in marked contrast to the extremely hard water found in Watonwan County in the formations that lie below the. drift and are supposed to be Cretaceous. It contains considerable quantities of sodium chloride, as is shown by analyses 5 and 6 in the accompany- ing table (p. 148). PALEOZOIC FORMATIONS. It is probable that remnants of the white Dresbach sandstone and underlying shale exist in the southeastern corner of the county, and they may have been penetrated in the mill well at Hanska. (See a U. S. Geol. and Geog. Survey Terr., vol. 6, pp. 6, 68, 76, 90, 93. Final Rept. Geol. and Nat. Hist, Survey Minnesota, vol. 1, 1882, pp. 98, 574, 576. 60920°— wsp 256—11 10 146 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. PL XVI and also the reports on Blue Earth and Watonwan coun- ties.) Wherever these formations are present they yield copiously. SIOUX QUARTZ ITE. Bodies of Sioux quartzite are known in several localities in the southwestern corner of this county, and in Nicollet County in the vicinity of New Ulm. The former, which is a part of the large quartz- ite area to the southwest, has several outcrops; the latter, which belongs to the smaller Courtland area, comes to the surface only in Nicollet County, opposite New Ulm. It is not known whether this rock is continuous between the two areas. It may exist at consid- erable depths in the south-central and southeastern parts of the county, but at Sleepy Eye and throughout the northern portion generally it is known to be absent. It contains only small quantities of water, of no economic value except in the southwestern corner, where no other supply is available. ARCHEAN ROCKS. Granitic rocks are exposed at various points in the Minnesota Valley on both sides of the river and are encountered at Sleepy Eye at a depth of about 200 feet (PI. III). In much of the northern part of the county the granitic surface probably lies directly under the drift, but southward from Sleepy Eye and New Ulm it slopes down and disappears below the Cretaceous, Paleozoic, and Algon- kian sediments. These rocks, which extend to an indefinite depth, will yield little or no water. WATER SUPPLIES FOR CITIES AND VILLAGES. New Ulm. — The city of New Ulm is situated upon several terraces on the west side of Minnesota River. The Cretaceous formations are exposed in the city, but on the undissected upland are covered by a thick mantle of glacial drift. At the pumping station of the city waterworks granite occurs at a depth of about 200 feet, but on the east side of the river both the quartzite and the granite come to the surface. The main water-bearing bed is a 20-foot stratum of sandstone at the base of the Cretaceous, about 150 feet below the river level. The public supply is taken from three wells about 195 feet deep, which tap this sandstone. The head and yield of these wells have already been given (p. 145). The water, an analysis of which will be found in the accompanying table (p. 14S), is used by about 3,400 people, and on an average about SO, 000 gallons is con- sumed daily. Perhaps 40 per cent of the inhabitants depend upon private wells, which can be classified into two groups ; — (1) shallow- dug wells ending in sand and gravel and generally supplying con- siderable water, and (2) drilled wells extending to the sandstone and yielding liberally. The Chicago and Northwestern Railway Company BROWN COUNTY. 147 and several of the breweries are supplied from wells belonging to the second group. An analysis of the water from the railway well is given in the table (p. 148). Sleepy Eye. — The stratigraphic section for this locality is shown in Plate VIII. The public supply is obtained from two wells, one of which is 4| inches in diameter and 180 feet deep and has been tested at 40 gallons per minute, and the other 4 inches in diameter and 222 feet deep and has been tested at 100 gallons per minute. The water is reported to rise to a level between 45 and 60 feet below the surface, or between 975 and 990 feet above the sea. It is used b} r about 400 people, approximately 29,000 gallons being consumed daily. The private wells for domestic supplies are generally between 15 and 75 feet in depth, but a few domestic wells and the wells which supply the Chicago and Northwestern Railway Company, the Sleepy Eye flouring mill, the electric-light plant, and several other indus- trial concerns extend to the 200-foot bed. The maximum test re- ported for any well entering this bed is 185 gallons a minute. The water is hard, as is shown by the analyses in the table. Springfield. — The village of Springfield lies on the banks of Cotton- wood River. The business portion is in the valley, while most of the dwellings are on the terraces and the upland. On the first terrace, which is only 5 or 10 feet above the flood plain, flows are obtained from a layer of sand about 30 feet below the surface. The uplands are underlain by glacial drift, but Cretaceous outcrops are found in the valley near the village. The people are at present dependent on private supplies. There are four types of wells — dug, driven, bored, and drilled. The dug wells are generally between 10 and 20 feet deep; the driven, between 10 and 35 feet; the bored, between 30 and 100 feet; and the drilled, between 100 and 150 feet. The dug and driven wells are chiefly in the valley and on the first terrace, where an abundance of water can be obtained from the alluvial deposits at shallow depths, while the drilled wells are on the upland. For boiler purposes water from the river is chiefly used. The public water- works were formerly supplied from two wells, 4 inches in diameter and 36 feet in depth, but are now reported to be supplied from springs. The water is pumped into an elevated tank and thence distributed through the mains by gravity pressure to about twenty-five taps. The average daily consumption is estimated at 30,000 gallons. Comfrey. — The village of Comfrey has a system of public water- works supplied from a well which is 8 inches in diameter and 140 feet deep, but the people generally use water from private wells. FARM WATER SUPPLIES. There are two principal types of farm wells in the county — (1) bored and dug wells and (2) drilled and driven wells. In the west- ern part of the county the former predominate, while in the eastern the latter are more numerous; but everywhere the drilled wells are gradually supplanting the dug and bored ones. Some of the latter 148 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. stop in the surficial zone of yellow clay, but many extent! into the blue bowlder clay and penetrate seams of sand and gravel at depths of 50 to 100 feet. The drilled wells extend to the deeper, gravelly portions of the drift, or, less frequently, enter the Cretaceous strata. They range from about 100 to 350 feet in depth, but seldom exceed 225 feet. The 2-inch wells that end in sand must be provided with screens, but screens are not generally necessary in wells of larger diameter, nor in wells that penetrate sandstone, even though their diameter is small. As elsewhere in southwestern Minnesota, the screens cause considerable annoyance by becoming incrusted with mineral substances deposited by the water. SUMMARY AND ANALYSES. Except in the southeastern part of the county, either the quartzite or the granite lies relatively near the surface. The quartzite con- tains small stores of water, but should not be penetrated except in the southwestern corner, where no other supplies can be obtained. The granite is not water bearing, and drilling should therefore not be continued when it is encountered. The beds of gravel, sand, and sandstone, in the formations above the quartzite or granite, gener- ally contain supplies sufficient for all ordinary purposes. No flows are to be expected except in small and unimportant areas, such as the one at Springfield. The water is generally hard, but averages somewhat softer in the sandstone than in the sand and gravel nearer the surface. Mineral analyses of water in Brown County. [Analyses in parts per million.] Springs. Surface deposits (glacial drift, etc.). Cretaceous. Depth feet. Diameter of well inches . Silica (SiOg) Iron and aluminum oxides (.Fe^Os+Alji > :i ) Calcium ( Ca) Magnesium ( Mg) Sodium and potassium (Na+ K) Carbonate radicle (COg) Bicarbonate radicle (HCO3) Sulphate radicle (SOj) Chlorine (CI) Nitrate radicle (NO3) Total solids ais 210 4 28 2.3 149 28 2.1 223 87 82 472 20 34 743 123 5 565 5S9 10 473 793 150 60 47 600 208 7 195 and S 288 223 131 70S 789 10 71 30 144 270 2.57 104 1. Springs at New Ulm. February 5, 1S90. 2. AVell at the roller mill in Sleepy Eve. July 1. 1889. 3. "City well" at Sleepy Eye. March 17, 1900. 4. Well at Sleepy Eve. July, 1S90. 5. City wells at New Ulm. August 16, 1007. 0. Depot well at New Ulm. April 30, 1892. Analysis 5 was made for the United States Geological Survey by H. A. Whittaker, chemist Minnesota state board of health; the others were furnished by G. M. Davidson, chemist Chicaeo and Northwestern Railway Company. UNDERGROUND WATERS OF SOUTHERN MINNESOTA. 149 CARVER COUNTY. By C. W. Hall and M. L. Fuller. SURFACE FEATURES. In the northeastern part of Carver County there is an area of rough topography, whence the surface stretches off toward the southwest into a broad level area. On the southeast the county is bounded by the deep, wide Minnesota Valley, near which the upland is consider- ably dissected. SURFACE DEPOSITS. The glacial drift is in general between 200 and 300 feet thick and yields satisfactory supplies of water from its gravelly beds. Upon the uplands stretching out from the morainic region of Hen- nepin County and the northeastern part of Carver County lies a broad expanse of outwash gravels, sands, and clays, reaching quite across the county toward the south and west. Extensive deposits of clays, which appear at Chaska and Carver, indicate an interesting lake stage in the history of Minnesota River near the close of glacial times. An unusual development of the terrace gravels is seen along the course of the Minnesota where it forms the boundary of the county. This gravel zone locally narrows to a few hundred feet, but is gener- ally 2 miles or more. Water is found in it in considerable quantities, except near the edges of the terraces. Recently deposited alluvium occurs in the Minnesota Valley and along several of the smaller streams, but is not important. ROCK FORMATIONS. Although the Cretaceous has never been found in this county it is possible that it will be discovered in future well drillings. The upper- most Palezoic formation present is probably the Oneota dolomite, which has been found in the neighborhood of Lake Minnesota and at Eden Prairie, in Hennepin County, and also in adjacent parts of Scott County. The first formation yet disclosed in the well drillings recorded from Carver County is the Jordan sandstone, which is present in the eastern part and has a thickness, where not eroded, of about 115 feet. It carries an abundance of water and is a valuable source of supply. The St. Lawrence formation, although usually containing much shale, in this county consists to a considerable extent of a yellow to red magnesian limestone. According to well records available, it is as much as 185 feet thick. It is not seen at the surface within this county, but St. Lawrence Township, in Scott County, on the oppo- site side of Minnesota River, is the type locality of the formation. a Second Ann. Rept. Geo!, and Nat. Hist. Survey of Minnesota, 1873, p. 150. 150 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Though it is saturated with water, it is so compact that it is not important as a water-bearing formation. The Dresbach sandstone and underlying shale were penetrated in the deep well at Chaska, where the drill apparently entered them a distance of 215 feet and reached an abundant supply of water under artesian pressure. It is probable that in the western part of the county the St. Lawrence and Jordan formations are both absent and that the Dresbach sandstone lies immediately below the drift. The section of the deep well at Glencoe to the west (given in the report on McLeod County) and the sections of wells to the north and south make it reasonably certain that water-bearing sandstones are present throughout this county. The following two well sections also give valuable information on this important point: Section of city tvell at Chaska, on the flood plain of Minnesota River. [Authority, the mayor of Chaska.] Brick clay "Hardpan" White sandstone [Jordan?] Shale [St. Lawrence?] White and red sandstone.. Shale Thick- ness. Depth. Feet. 150 50 80 185 200 15 Feet. 150 200 280 465 665 Section of railway well at Hamburg. [Authority, chemist Minneapolis and St. Louis Railroad.] Thick- ness. Depth. Surface soil Yellow clay Blue clay "Hardpan" Soft yellow clay "Hardpan"../ Water-bearing sand White sandstone.. . Feet. 35 Feet. 1 8 75 119 125 203 209 244 HEAD OF THE WATER. On the uplands the water in the surficial sand and gravel stands very near the surface, while that from the deeper horizons, although under considerable pressure, remains some distance below the surface. In the Minnesota Valley, along the southeastern border of the county, however, the water from the deeper formations rises above the sur- face, good flowing wells being obtained at Chaska and Carver. In the abandoned railway well at Hamburg the water stood 90 feet below the surface, or about 910 feet above sea level; in the city well at Chaska it is reported to rise 30 feet above the surface, or about 780 feet above sea level. CHIPPEWA COUNTY. 151 TABLE OF ANALYSES. In the following table, analysis 3 was furnished by the chemist of the Minneapolis and St. Louis Railroad; the others by G. N. Prentiss, chemist, Chicago, Milwaukee and St. Paul Railway Company: Mineral analyses of water in Carver County. [Analyses in parts per million.] Glacial drift. Depth feet Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+K) Bicarbonate radicle (HC0 3 ) Sulphate radicle (SO4) • Chlorine (CI) Total solids 100 150 53 20 482 228 2.7 695 233 145 50 51 625 152 1.9 712 Oneota(?) dolomite. 2 416 22 3 Jordan sandstone. 491 69 32 9.7 387 6.6 2.1 310 400 145 52 44 600 169 2.8 707 a Spring. 1. Well at Chanhassen. November 22, 1897. 2. Well at Cologne. November 15, 1894. 3. Spring at Carver, owned by the Minneapolis and St. Louis Railroad Company. 1892. 4. Well at Chanhassen. August 14, 1902. 5. Well at Cologne. August 4, 1902. CHIPPEWA COUNTY. By O. E. Meinzer. SURFACE FEATURES. Chippewa is a typical prairie county, with very imperfect drainage and numerous lakes and ponds. Minnesota River, which here occu- pies a valley 1 to 2 miles wide and 100 to 150 feet deep, forms the southwestern boundary. Its principal affluents in this county are Chippewa River and Hawk Creek, two streams which have cut rather deep trenches into the upland but have developed only short tribu- taries and hence have left the extensive interstream areas quite unaffected by erosion. There are several interesting deserted river channels associated with the Minnesota Valley. One of these starts from the bend of Pomme de Terre River, east of Appleton, and extends southeastward to the vicinity of Watson, where it joins the valley of Chippew T a River, which has an unusual wddth from this point to where it opens into the Minnesota Valley at Montevideo. This deserted channel is also ^connected with the Minnesota Valley by a channel north of Milan and another more prominent one midway between Milan and Watson." a Upham, Warren, Final Kept. Geol. and Nat. Hist. Survey Minnesota, vol. 2, 1885, p. 208. 152 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. SURFACE DEPOSITS. Description. — The glacial drift forms a continuous cover for the entire county except in a number of small areas near Minnesota River where the granite has been exposed by stream erosion. Its average thickness is 200 feet or somewhat less. On the upland bordering the Minnesota Valley it is about 150 feet, but it increases gradually toward the northeast. However, on account of irregularities in the surface upon which the drift rests, the thickness varies considerably within short distances. Yield of water. — The glacial drift is the only source of water that can be relied on. Where it is thick enough it usually includes one or more sand and gravel seams saturated with water and capable of pro- viding supplies adequate for ordinary purposes; but where it is thin it is likely to be devoid of any satisfactory water-bearing bed, as at Montevideo and in other localities. Head of the water. — The water from the drift nearly everywhere rises close to the surface. Flowing wells with slight pressure are found in the valley of Chippewa River north of Watson, and one or two are reported in the village of Milan. It is probable that they can be secured in other low tracts, but there is no important flowing area. Quality of the water. — The reports on Swift, Kandiyohi, and Renville counties show that in this region the water from the upper portion of the drift includes large quantities of calcium and sulphates, while that from the lower portion generally contains less calcium and rela- tively small quantities of sulphates. The shallow water is therefore harder than that from deeper sources and is poorer for boiler purposes.' What is true in the adjoining counties is probably also true in this county, although no specific data were obtained. CRETACEOUS DEPOSITS. The Cretaceous deposits consist of soft, blue shale (" soapstone ") and thin strata of sand. They have been encountered in several wells in this county and are found in all the counties bordering on Chippewa. Their total thickness is nowhere great, perhaps rarely 100 feet, while in the vicinity of Montevideo and Granite Falls, and in other localities, they are known to be absent. When the Cretaceous shale is reached in drilling there is little probability of obtaining water, but in rare instances a satisfactory water-bearing bed of sand is discovered below the shale. The typical Cretaceous water is soft, but contains large quantities of alkali and of sulphates and chlorine. (See the reports on Bigstone, Lac qui Parle, and Yellow Medicine counties.) There is probably no Cretaceous water in this county that has not been mixed with water from the drift. CHIPPEWA COUNTY. 153 ARCHEAN ROCKS. The granitic rocks are exposed in a number of places near Min- nesota River (Pi. Ill) and underlie this entire county at depths which at few if any points exceed 500 feet. On the uplands near Granite Falls granite was struck at a depth of about 200 feet; in the vicinity of Montevideo, at about 130 feet; and in the village of Milan, at about 200 feet. In the northeast it is more deeply buried, but from the available data it appears improbable that it lies very far below the surface anywhere within this county. As in other sections of southwestern Minnesota, the upper part of the granite is generally much decomposed, and in many places is overlain by white clay. At the stock yards in Montevideo this clay is reported to have been penetrated to a depth of 70 feet. It is with- out doubt a product of the granitic rock, but its thickness in some localities, its freedom from grit in many places, and the fact that it includes some interbedded layers of sand, all indicate that in part it has been transported and redeposited by water; in other words, it is a sedimentary deposit rather than a granitic residuum. If, as is prob- able, the sedimentation took place when the Cretaceous seas invaded the region, the white clay is in part a sort of basal Cretaceous forma- tion. When the white clay or ordinary granitic residuum is encoun- tered there is little probability of securing water, though successful wells are occasionally finished in these materials. After the solid granite has been entered there is virtually no hope of getting water. WATER SUPPLIES FOR CITIES AND VILLAGES. Montevideo. — The granite lies near the surface and in many places is covered by a layer of white clay. The glacial drift is thin, but is virtually the only water-bearing formation, there being no deep or strong water zone. No soft water is available, but the analyses given in the table show a considerable variation in hardness. The public supply is secured from springs about 1 mile north of the village, whence the water is conducted by gravity to the pumping station. In 1907 the springs yielded about half a million gallons per day, only about one-fifth of which was utilized. In view of the meager ground-water resources of the village, these springs must be considered invaluable. About two-thirds of the people use water from private wells, which are either bored or dug and end in sand or yellow clay at depths of about 20 to 30 feet. The yield of these wells is small and is easily affected by drought. Milan— In the village of Milan the granitic rocks are about 200 feet below the surface, and are overlain by a thin bed of shale. The water supply is derived from the glacial drift, chiefly from wells ranging between 20 and 60 feet in depth. The public supply, which is not yet 154 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. extensively used, comes from a well 9 feet in diameter and 25 feet in depth. Maynard. — All the people in this settlement use water from private wells, the public waterworks being maintained almost exclusively for fire protection. FARM WATER SUPPLIES. There are two principal types of farm wells, bored and drilled. The former, which are shallow and do not always yield adequate sup- plies in dry years, are gradually being replaced by drilled wells. The latter do not average much over 100 feet in depth. The 2-inch wells require screens, but the wells of larger diameter are finished success- fully with open ends. Since the screens are liable to become clogged in the course of a few years, their use should be avoided wherever possible, and for this reason 6-inch wells are recommended for farm purposes. SUMMARY AND ANALYSES. In all sections of the county the granitic rocks lie within a few hundred feet of the surface. Since granite will not yield water and there is no water-bearing formation below it, deep drilling should not be undertaken. In rare instances small supplies are found after the shale ("soapstone"), the white clay, or the ordinary decomposed granite are reached, but the glacial drift is the only reliable source of water. Analyses of water from the upper and lower portions of the drift at Benson, Willmar, Grove City, Renville, Olivia, Bird Island, Hector, and other places east of Chippewa County show that the water from the lower portion has much less permanent hardness than that from the upper. Since the same is probably true in the parts of Chippewa County where the drift has considerable thickness, drilling to the deeper drift horizons is recommended. Near the Minnesota Valley, where the drift is relatively thin, the beds containing the softer water are likely to be absent. Mineral analyses of water in Chippeiva County. [Analyses in parts per million.] Depth fee t . Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+K) Bicarbonate radicle (HCO3) Sulphate radicle (SOj) Chlorine (CI) Total solids 1. 0. 3. CO 100 75 201 14(i 43 32 67 37 42 195 439 4C4 651 241 5 99 7 8 399 089 461 1,281 91 32 19 190 663 19 588 1. Springs north of Montevideo, used for public supply. November 23. 1907. 2. "Casgreve's well" at Montevideo. November 23, 1907. 3. "Clark's well" at Montevideo. November 23, 1907. 4. Railway well at Milan. December 2, 1897. The above analyses were furnished by G. N. Prentiss, chemist Chicago, Milwaukee and St. Paul Railway Company. UNDERGROUND WATERS OF SOUTHERN MINNESOTA. 155 COTTONWOOD COUNTY. By O. E. Meinzek. SURFACE FEATURES. The prevailing topography of Cottonwood County is that of a nearly level and poorly drained prairie. But this topograph}' is modified in the north by a ridge of quartzite and in the south and west by a morainic belt. The eastern portion of the quartzite ridge rises from 1,300 to 1,500 feet above sea level and stands prominently above the surrounding country, especially above the region to the north. Westward it becomes wider but less conspicuous as a plrysiographic feature. Its trend is shown in Plate IV. Mound Creek, Little Cottonwood River, and one of the branches of Watonwan River all flow across this ridge and have cut little canyons into it. The morainic belt forks at Windom, one arm extending to the north, and the other to the northwest in the direction of Westbrook and Currie. The Blue Mounds constitute the most prominent portion of the moraine, and reach an altitude of about 1,500 feet above the sea. a Cottonwood County is drained northward into Cottonwood River, eastward into the Watonwan, and southward into the Des Moines. The last-named stream flows through the southwestern part, follow- ing a peculiar course. It enters from Murra}" County, running southeastward apparently along the trend of an ancient valley in which Lake Shetek and Heron Lake now lie. Where it reaches the Jackson County line it turns abruptly and flows northeastward for 8 or 9 miles, where it meets a valley from the north and again turns toward the southeast. It occupies a valley that has been cut con- siderably below the upland surface. SURFACE DEPOSITS. Description. — The glacial drift forms a nearly continuous cover for the older formations, being interrupted only in the small areas where the Sioux quartzite comes to the surface. A general con- ception of its thickness can be acquired from Plate II and from the ensuing discussion of the Cretaceous and Algonkian. Over an extended region in the central, east-central, and northeastern parts of the county it has an average thickness of less than 100 feet, and in many localities of less than 50 feet; but in the southern, western, and extreme northern parts its thickness ranges from 200 to more than 300 feet. In drilling the city well at Windom the drift was found to be 250 feet deep, and in a number of other wells in this aUpham, Warren, Final Rept. Geol. and Nat. Hist. Survey Minnesota, vol. 1, 1882, p. 491 et seq. 156 UNDERGROUND WATERS OP SOUTHERN MINNESOTA. vicinity between 250 and 300 feet. Near the western margin of the county the entire drift sheet has seldom been penetrated. Yield of water. — Where the drift is thick it usually includes layers of sand or gravel that afford sufficient water for farm purposes and also for ordinary industrial and public supplies; but in the central and eastern parts, where it is thin, it is frequently found to be devoid of any bed that will yield much water. The alluvium of the Des- Moines Valley yields abundantly from very shallow depths. Head of the water. — Throughout the county the water from the drift is under considerable artesian pressure, commonly rising within 50 feet and frequently within 25 feet of the top of the well. Although there is no extensive area in which flows can be obtained, there are several small ones, most of which are related to the quartzite ridge. The latter stands higher than the surrounding country, and the drift laps up over it. A part of the rain that falls on this elevated ground is transmitted, either directly or through the pervious portions of the rock, to the sand and gravel seams of the drift. Wherever there is an opportunit}^ the water leaks out and flows to a lower level, thus producing many springs along the margins of the ridge. But where the impervious bowlder clay extends up over the rock the water is confined, and hence accumulates head and gives rise to conditions requisite for obtaining flowing wells. These relations are shown in a diagrammatic way in figure 4. In the valley of Des Moines River all along its course the water from shallow horizons is raised approximately to the surface, and flowing wells could probably be secured in some localities. Quality of the water. — The water from the glacial drift is all hard. In the accompanying table of analyses (p. 162), Nos. 3, 4, and 5 repre- sent water from moderate depths in the drift, and it will be seen that all three of these samples have an extremely high content of calcium and of the sulphate radicle for which reason they have a very great permanent hardness and will produce much hard scale in boilers. In the same table Nos. 1 and 2 represent water from deposits of sand and gravel near the surface, which, although also hard, has a much smaller content of scale-forming minerals. CRETACEOUS SYSTEM. Description. — Shales and sandstones have been encountered in several wells in the vicinities of Windom and Westbrook and in many wells immediately north of this county. The section of the city well at Windom shown in Plate IX is typical for that region. The well at the flouring mill at Westbrook, 568 feet deep, and the one drilled for the railway company in the same village, 642 feet deep, are both reported to pass through a certain amount of shale and to end in sandstone. It is evident from these data that a wedge U. S. GEOLOGICAL SURVEY WATER-SUPPLY PAPER 256 PLATE IX GEOLOGIC SECTIONS IN SOUTHERN COTTONWOOD AND NORTHERN JACKSON COUNTIES. By O. E. Meinzer. Heron Lake. — Well drilled in 1905 in village of Heron Lake for Chicago, St. Paul, Minneapolis and Omaha Railway Company. Authority, G. J. Savidge, driller, Wayne, Nebr. Near Heron Lake. — Well on farm of Mr. Runser, 1J miles north- east of Heron Lake. Authority, E. W. Anderson, driller, Heron Lake. Wilder. — Well 1 mile northwest of Wilder, on farm of C. B. Cheadle. South of Windom. — Well 5 miles south of Windom, on farm of Arthur Johnson. This section and the one preceding are given on the authority of H. Hanson, driller, Windom. Windom. — Approximate section reported for the deep city well. The altitudes of the second, third, and fourth sections are only approximately known. COTTONWOOD COUNTY. 157 of shale and sandstone enters the county from the south, west, and north, between the glacial drift and the quartzite. It is probably all Cretaceous in age, although the lower portion may be in part Paleozoic. If the drift were all removed from Cottonwood County, about one-half of the surface (the central, northeastern, and east- central parts) would constitute a quartzite area standing conspicu- ously above the adjacent region and surrounded and overlapped by nearly horizontal strata of Cretaceous sediments, somewhat as the ocean surrounds and overlaps an island. Yield of water. — In the vicinity of Windom several wells have been successfully finished at a depth of about 300 feet in beds of Cretaceous sands. The city well at Windom, which was given the most severe test, was pumped continuously for twenty-four hours at the rate of 120 gallons a minute. At Westbrook and Lamberton drilling into the Cretaceous has been less successful. The mill well at Westbrook does not yield a great supply, and the railway well seems never to have been satisfactory. At Lamberton no water- bearing stratum of consequence was found after the shale was entered, but in the vicinities of Walnut Grove, Revere, and San- born there are many good wells supplied apparently from the Cretaceous. Head of the water. — At Windom the Cretaceous water rises to a level about 100 feet below the surface, or approximately 1,260 feet above the sea; in the mill well at Westbrook (according to report) to about 50 feet below the surface, or 1,370 feet above the sea; and at Walnut Grove, near the northwest corner of this county, to about 12 feet below the surface, or 1,216 feet above the sea. The Cre- taceous area of flowing wells of Lyon and Redwood counties extends approximately to the Cottonwood county line (PI. IV). Quality of the water. — Two distinct types of water are derived from the Cretaceous strata of this region. Both are highly mineralized and both are rich in sulphates, but in one the sulphate radicle is in equilibrium chiefly with calcium and magnesium, giving the water a great permanent hardness and causing it to form much hard scale in boilers, while in the other the content of calcium and magnesium is low, and the sulphate radicle is to a much greater extent associ- ated with sodium and potassium, producing a soft water, which is liable, however, to cause foaming in boilers. The water obtained from the Cretaceous wells in the vicinity of Windom and that from the deep railway well at Westbrook belong to the first type, while the water from the mill well at Westbrook and that from the Cre- taceous wells in the region of Walnut Grove and Revere belong to to the second. Analyses 6, 7, 9, and 10, in the accompanying table, represent water of the first type; No. 8, water of the second. Soft- water horizons occur under Walnut Grove at 900 feet above sea 158 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. level and higher, and under Westbrook at about 850 feet above sea level. Hard water seems to be found both above and below the soft. The city well at Windom terminates about 1,080 feet above the sea, and the other Cretaceous wells of that section at approxi- mately the same level. Although it is by no means safe to infer that softer water can be secured at Windom by drilling deeper, yet there is reason for believing that it may. It must be remem- bered that the mill well at Westbrook has only a small yield, and probably draws from a thin layer which may not furnish enough water to supply a well in other localities, and which, in careless drilling, can readily be passed through unnoticed. SIOUX QUARTZITE. Description. — This formation consists of a hard, red, siliceous rock, properly called quartzite, but commonly known throughout the region as the "red rock." The second tier of townships from the north contains the main quartzite ridge, and east of Highwater Creek there are many outcrops. The most westerly exposure is found along Highwater Creek, east of the village of Storden; the most southerly, in sec. 12, T. 106 N., R. 37 W. ; and the most north- erly, along Mound Creek, in T. 108 N., R. 36 W. (PL III). A ledge of rock, with an east-west or slightly southeast-northwest trend, seems to run beneath the village of Mountain Lake. It is entirely covered by drift, but is frequently encountered in drilling. Quartzite was struck 5 miles east and a little south of Mountain Lake, at a depth of 90 feet; in the village of Mountain Lake, at 70 feet; 7 miles west and a little north of the village, at 60 feet; 2 miles farther west, at 40 feet; and at intermediate points along this line, at less than 100 feet. The well data that have been secured are too meager to show whether this is a ridge separated by a depression from the main ridge in the northern part of the county or rather the southern edge of a quartzite plateau continuous with the main ridge. West of the last-named locality (which is sec. 25, T. 106 N., R. 36 W.), the rock has not been encountered, and there is good reason to believe that it lies at a considerable depth; but 7 miles northwest (sec. 12, T. 106 N., R. 37 W.) it comes to the surface. Likewise, east of Jeffers (NW. I sec. 22, T. 107 N., R. 36 W.), a well 230 feet deep was drilled without reaching rock, while in the village of Jeffers it occurs at 104 feet. These data seem to indicate an ancient valley in the quartzite of this region. Yield of water. — This formation affords small quantities of water from its joint fissures and less firmly cemented layers. If in drill- ing a well a moderate yield is obtained before the rock is struck, the rock should not be penetrated for additional supplies ; but where the quartzite is near the surface and the yield of the overlying drift COTTONWOOD COUNTY. 159 is small and uncertain, it is advisable to drill into the rock. Where attempts to get water from the quartzite have failed the reason has usually been that drilling was not continued to a sufficient depth. Quality of the water. — The quartzite itself contributes very little mineral matter, but its water, if it is derived from overlying glacial drift or Cretaceous strata, receives mineral constituents from these sources before it enters the quartzite. There is therefore a wide range in the content of the water from this formation. WATER SUPPLIES FOR CITIES AND VILLAGES. Windom. — The city of Windom lies on the banks of Des Moines River. On the upland the glacial drift is about 300 feet deep, and the entire valley has been excavated out of this material (PI. IX). The public supply is a mixture of water from three zones — (1) surface clay and sand, which contribute water to a reservoir 14 feet in diam- eter and 16 feet deep; (2) a bed of sand and gravel at a depth of 65 feet, which supplies five 3-inch driven wells, the water rising about 10 feet below the surface; and (3) a stratum of sand at a depth of 280 feet, which supplies an 8-inch drilled well already men- tioned. The 16-foot well is intended at present only as a reservoir to receive the natural flow of the driven wells, but it is not entirely waterproof and admits some shallow water. In 1907 the five driven wells would together yield several hundred gallons per minute when the 16-foot well was emptied so that they were given a head of about 6 feet. They furnish most of the public supply, having an advantage over the deep well both in head and in the mineral quality of the water. Perhaps 25 per cent of the inhabitants utilize the public supply to some extent, but few use it exclusively. About 15,000 gallons are consumed daily. Nearly all the people have private wells, many of which are driven into the surficial sands. The rail- way company uses water from a shallow well. Mountain Lake. — Quartzite has here been found at a depth of 70 feet. Above the rock lies the glacial drift, which in some parts of the village contains beds of water-bearing sand. The public water- works are supplied from a well that is 12 feet in diameter and stops in a bed of sand at a depth of 40 feet. Its yield is not great and is much affected by drought. In July, 1907, pumping at the rate of approximately 50 gallons per minute lowered the water level from 20 feet below the surface to 30 feet, while in the autumn of 1906 the well could be emptied in 2^ hours. Although the water is hard, it is much better in this respect than that from the bottom of the drift, as can be seen by a comparison of analyses 2 and 3 in the table. About 400 people use the public supply, and it is also used at the mill and the creamery. On an average approximately 20,000 gallons is con- sumed daily. The private wells are for the most part bored a short 160 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. distance into the glacial drift. Where good beds of sand occur they provide ample supplies for domestic purposes, but where these are wanting it is often difficult to get a sufficiently large and permanent yield, and the water is not always good. The railway company has a well that is drilled into the quartzite. WestbrooJc. — The drift, which is deep in this locality, is underlain by Cretaceous shales and sandstones. Drilling 642 feet deep has not reached the quartzite. All the people use water from private wells, which are commonly between 15 and 30 feet in depth and rarely exceed 75 feet. They end in yellow clay or in sand and gravel and many of them furnish only small quantities of water and fail in dry years. A bored well, 3 feet in diameter and 64 feet deep, supplies the public waterworks. It is reported to have the follow- ing section: Section of village well at Westbrooh. [Authority, Bert Milligan, borer, Westbrook.] Thick- ness. Depth. Yellow clay.. Blue clay] Blue sand, v.. Blue clay I Sand (.water). Feet. 17 Feet. IT In this well the water stands about 25 feet below the surface, and pumping at the rate of 25 gallons per minute empties the well in a little over an hour. The water that it yields is hard, as is shown by analysis 4 in the table, and is used only for the railway locomotives, for sprinkling the streets, and for fire protection. The mill welh which yields soft water, and the deep well drilled for the railway company have already been discussed. FARM WATER SUPPLIES. The wells which furnish farm supplies may be grouped into the following classes: (1) Wells driven^ into the surficial sandy deposits, (2) wells bored into yellow clay or gravelly beds near the surface, (3) wells bored into seams of sand and gravel interbedded with the blue bowlder clay, (4) wells drilled into these deeper seams, (5) wells drilled into Cretaceous strata of sand or sandstone, and (6) wells drilled into quartzite. The wells of the first group are virtually confined to the valley of Des Moines Kiver. Those of the second are generally unsatisfactory because of their small and uncertain supplies COTTONWOOD COUNTY. 161 of water, and have to a great extent been abandoned for deeper wells, while most of those of the third group yield adequate and per- manent supplies and comprise a majority of the farm wells of the county. There are also many wells belonging to the fourth group and a few belonging to the last two. Drilled wells have a number of advantages over bored ones, and wells from 4 to 6 inches in diam- eter prove more satisfactory than those which are only 2 inches in diameter. Drilling into quartzite is avoided as much as possible because of the expense and difficulties involved. It is necessarily an expensive process, and it is well for a farmer fully to understand that fact before- hand. It is sometimes necessary to sink several hundred feet into the rock in order to get an adequate yield, while the cost per foot is great and increases with the depth. However, rock wells rarely need be failures. A driller with a heavy rig and a comprehensive knowl- edge of his trade can penetrate quartzite to an indefinite depth, and is seldom obliged to abandon a hole. But this kind of work presents peculiar difficulties and should not be undertaken without a thor- ough apprenticeship, nor with an outfit that is too light. The drill- ing of wells in quartzite is discussed on pages 87-88. SUMMARY AND ANALYSES. Public, industrial, and private supplies are obtained chiefly from seams of sand and gravel interbedded with bowlder clay, and these will always be the most accessible and valuable sources. The strata of sand and sandstone found beneath shale (" soap- stone") in the southern and western portions of the county, at depths of 300 feet or more, generally but not always yield large quantities of water. The water from this source will rise to a level about 100 feet below the surface at the southern margin of the county, and vir- tually to the surface at the northern. Deep drilling should not be undertaken for the purpose of securing flowing wells except in the northwestern corner. In the northern part both hard and soft water horizons have been discovered. In the southern only hard water has thus far been found, although it is possible that softer water exists at greater depths than have yet been reached. (See the reports on adjoining counties.) Where the Sioux quartzite ("red rock") is so near the surface that no adequate source of water is found above it, it is advisable to drill into the rock, which if penetrated to a sufficient depth will in nearly all instances provide permanent though small supplies, 60920°— wsp 256—11 11 162 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Mineral analyses of water in Cottonwood County. [Analyses in parts per million.] Surface deposits (glacial drift, etc.). Cretaceous. Depth feet.. Diameter of well i .ich.es. . Silica(Si0 2 ) Iron (Fe) Iron and aluminum oxides (FeaOs+AlsOa) Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+K) Carbonate radicle (CO3) Bicarbonate radicle (HCO3) Sulphate radicle (SOj) Chlorine (CI) Nitrate radicle (NO3) Total solids 40 144 60 156 28 26 713 133 42 21 .0 456 157 11 3.5 611 313 105 127 1.7 235 78 142 4 302 102 114 527 1,012 3 504 769 3 620 876 1,846 1,501 1,729 292 2 14 2.5 11 158 57 43 .0 459 346 3 .0 845 320 8 31 568 2 642 8 33 642 8 21 219 75 150 37 9 512 287 99 129 6.4 159 46 3-18 539 705 6 1,545 283 933 13 2.1 1,710 713 759 19 385 971 12 1,677 1,797 1. Railway well at Windom. December 5, 1900. 2. Village well at Mountain Lake. July 18, 1907. 3. Well at Mountain Lake. January, 1900. 4. Village well at Westbrook. July 9, 1903. 5. Creamery well at Bingham Lake. January, 1900. 6. Well of A. E. Johnson, 5 miles south of Windom (Jackson County). July 19, 1907. 7. Railway well at Bingham Lake. June 21, 1900. 8. Well at the flouring mill at Westbrook. December 26, 1907. 9. Railway well at Westbrook. May 16, 1901. 10. Railway well at Westbrook. June 28, 1901. Analyses 2 and 6 were made for the United States Geological Survey by II. A. Whittaker, chemist Min- nesota state board of health. Analysis 8 was made for the United States Geological Survey by M. G. Rob- erts, chemist Minnesota state board of health. Analyses 1, 3, 4, 5, 7, 9, and 10 were furnished by G. N. Prentiss, chemist Chicago, Milwaukee and St. Paul Railway Company. DAKOTA COUNTY. By C. W. Hall and M. L. Fuller. SURFACE FEATURES. Dakota County is one of the lowest of those bordering Mississippi River in southeastern Minnesota. The greater part of the land is less than 1 ; 050 feet above sea level, or only 200 to 300 feet above the river. The plateau character is less marked than in most counties, owing to the irregularity of the morainic surface in the eastern and northern parts of the county. Throughout this morainic area the surface is a confused jumble of sharp cones and irregular gravelly hills of all sorts, alternating with sharp hopper-shaped or irregular basins of great depth, often occupied by ponds and lakes. In many places the eleva- tion varies 100 to 150 feet within a distance of a few rods. The rock surface south of the moraine, and especially in the southern portion of the county, is somewhat irregular, owing to the fact that the softer rocks have been worn down to levels considerably lower than the more resistant beds, such as the Galena limestone, Decorah shale, and Platteville limestone afford. At several points these limestones give rise to mounds and flat-crested hills, resembling the buttes and mesas of the West. DAKOTA COUNTY. 163 Both Mississippi and Minnesota rivers are bordered by bluffs, but of different character, those of the former being generally of rock, while those of the latter are commonly of drift. Both streams have flood plains 1 to 2 or more miles in width. With the exception of these streams and Vermilion and Cannon rivers, the county is without important drainage lines, and shows little to suggest the deep sharp valleys and intervening narrow-crested ridges so characteristic of the counties of the southeast. This fact is due in part to its slighter elevation above the Mississippi and the consequent low grade of the streams, and in part to the presence of the drift covering which has filled the ancient valleys. Other irregularities are due to the effect of glacial and interglacial drainage in scouring out channels or forming terraces along the sides of the valleys. Among these lines of glacial drainage may be men- tioned particularly one leading from near Mendota southeastward across the moraine to the Mississippi Valley near Gray Cloud Island; one extending from Minnesota River near the county line in T. 115 N., R. 20 W., southeast to the vicinity of Farmington; another entering the county near Prairie Lake and extending eastward to the Vermilion Valley by way of Fairfield and Farmington; and those through the valley of Cannon River by way of its tributary, Chub Creek. Through all these ancient valleys large volumes of water poured from the ice in the west, excavating broad channels, often bordered by noticeable bluffs, and depositing extensive sheets of sand and gravel. At this time the Mississippi was flowing at an elevation of 100 to 150 feet above its present level, and, together with the glacial channels men- tioned, formed the long terrace at Inver Grove and extensive terrace flats in the vicinity of Hastings. At a later period the drainage of this region became readjusted, several of the valleys were filled with morainic material, and the streams then remaining began to erode the earlier deposits, eventually excavating the channels in which they now flow. On their sides remnants of the old levels are preserved as terraces standing 100 to 200 feet above the present bottoms. These terraces are now prominent features of the valley walls along Missis- sippi, Minnesota, and Cannon rivers. SURFACE DEPOSITS. The alluvium of Dakota County is a loamy stratified sand and gravel deposited by the present streams in the Mississippi and associated valleys. Its thickness reaches a maximum of 100 feet or more. Considerable water occurs in the materials, but owing to the silt present it is sometimes given up very slowly. Supplies for domestic purposes and for small industrial establishments can generally be obtained, 164 UNDERGROUND WATERS OE SOUTHERN MINNESOTA. The terrace sands and gravels lie 100 to 125 feet or more above the streams. They occur in narrow belts along the Mississippi south of St. Paul, widening out at the eastward swing of the river to a point near Hastings, where they are over 10 miles wide. They are 100 feet thick or more in most places, and at a few points reach a thickness of over 200 feet, as in the buried channel of the Mississippi beneath the Hastings Prairie. They contain considerable water in places, but, because of their porous nature, are freely drained on the side toward the valleys, making it necessary for wells to go nearly to the river level before obtaining permanent supplies. In many localities rock or drift is encountered before this level is reached, and here the wells usually fail to secure adequate supplies from the terrace deposits. This is true at several points on the Hastings Prairie. Outwash gravels, which are stratified deposits made by the waters flowing from the ice front in the Pleistocene epoch, occur in valleys southeast of Mendota, at Crystal Lake, along Vermilion River near Farmington, and along Cannon River in the southern part of the county. Water is found in them in considerable amounts, supplied partly by rainfall and partly by inflow from the surrounding hills. It is usually near the surface and is available to wells of ordinary depth, affording ample supplies for farm and domestic or small industrial purposes. The glacial drift is of two types — (1) the older or pre- Wisconsin drift, which underlies the uplands in the eastern two-thirds of the county, and is usually a thin deposit and not an important source of supply, although it carries some water in its sandy beds; and (2) the younger or Wisconsin drift, which is distinguished from the older drift by the absence of weathering. It constitutes the surface formation over a considerable part of the western portion of the county, in places reaching a thickness of 100 feet or more. Being of greater depth, it is a better source of supply than the older drift and yields water to a large number of farm wells. In general, how- ever, the available amounts are not sufficient for large industrial or public supplies. ROCK FORMATIONS. In this county the series comprising the Galena limestone, Decorah shale, and Platteville limestone is prevailingly shaly, but contains some thin layers of limestone. The lowest 20 feet consists of two beds of magnesian limestone separated by a bed of crumbling and rapidly disintegrating shale. The maximum thickness of these rocks in this county appears to be about 175 feet. They underlie the larger part of northwestern Dakota County, the best exposures being in the highlands south of St. Paul. Over the greater part of the area they are covered by thick deposits of drift and are penetrated by DAKOTA COUNTY. 165 but few wells. Near the river the water from these beds has been drained away, but elsewhere the supply is somewhat larger, though generally less than in the overhang drift. The St. Peter sandstone has a maximum thickness in Dakota County of about 160 feet. It outcrops along the valley of the Missis- sippi and forms the surface formation over extensive upland areas in the southwestern part of the county- Beneath the shaly beds that occur in the lower part of the formation considerable amounts of water under artesian pressure are found. The upper part of the for- mation, however, has been largely drained of its supplies by the deep gorge of the Mississippi. In the uplands, where they are not drained by adjacent valleys, good supplies are afforded to dug and drilled wells, but the water, being unconfined, is under little head and is not sufficient in amount to meet the needs of large industries or public supplies. The Shakopee dolomite, which here is about 25 feet thick, underlies considerable areas of the uplands as well as the Vermilion and Cannon river valleys. It carries some water in interbedded lenses of sandstone and in the joints and caverns formed by the extensive leaching the formation has undergone, but the amounts are less than in the over- lying drift. Near the Mississippi even these small supplies are lost by drainage. The New Richmond sandstone, which appears to have a consider- able thickness in its typical development in southern Minnesota, is not recognized everywhere in this county. In some localities, how- ever, it appears to be present and to yield supplies to many private wells. The yield would probably nowhere be sufficient for public supplies. The Oneota dolomite, which is petrographically similar to the Shakopee, occurs at the surface along Mississippi River near Hast- ings and for some distance south, and underlies the entire county. It carries a little water which is yielded to private wells, especially near Hastings. It is important as providing a cap to confine the waters of the underlying sandstone. The Jordan sandstone underlies the Mississippi Valley in the northern part of the county and affords abundant supplies for all ordinary purposes. The water is under sufficient head to carry it considerably above the river level. The St. Lawrence formation consists of alternating beds of lime- stone, shale, etc. It has a total thickness of about 200 feet, of which 75 feet is exposed above the river level below Hastings. It contains little water. The Dresbach sandstone lies beneath the St. Lawrence formation and is in turn underlain by shales. The sandstone beds are generally saturated with water under considerable pressure and afford supplies 166 UNDERGROUND WATERS OE SOUTHERN MINNESOTA. adequate for all ordinary demands. In the valleys of Mississippi and Cannon rivers they give rise to flows. The red clastic series underlies the shales last mentioned, and is found in all drillings in southeastern Minnesota which have pene- trated to. that depth. In thickness these rocks vary more than any other division in this part of the State. They are of but little value for yielding water supplies. WELL RECORDS. Below are given three typical well sections together with the prob- able correlations of the strata: Section of Chicago, Milwaukee and St. Paul Railway well at Mendota. [Authorities: W. E. Swan, driller; N. H. Winchell, Thirteenth Ann. Rept. Geol. and Nat. Hist. Survey Minnesota, 18S5, pp. 55-56; C W. Hall, Bull. Minnesota Acad. Nat. Sci., vol. 3, No. 1, 1889, p. 141.] Thick- ness. Depth. St. Peter sandstone, including talus Shakopee dolomite New Richmond sandstone (estimated) Oneota dolomite Jordan sandstone St. Lawrence and lower formations: Gray shale Green shale .' Limestone Blue shale Sandstone "Hard" rock,, inclosing beds of shale (not sandstone) Feet. 147 40 15 90 95 50 110 10 30 125 145 Feet. 147 187 202 292 387 437 547 557 587 712 857 Section of Swift & Co. well at South St. Paul. Thick- ness. Depth. Feet. 40 125 130 155 50 140 200 40 Feet. 40 165 295 St. Lawrence and lower formations: 450 500 Shale 640 840 Red clastic series 880 DAKOTA COUNTY. 167 Section of Chicago, Milwaukee and St. Paul Railway well at Hastings. Oneota dolomite: Ordinary magnesian limestone White sandstone Sandy magnesian limestone Jordan sandstone: Sandstone, somewhat ferruginous St. Lawrence and underlying formations: White sandy shale Sand, sandy shale, and dolomite Sand, and green sand Green shale and green sand Sandy shale, sand, and green sand Dresbach sandstone, with lumps of iron pyrite Green sandy shale Blue shale Sand, and green sand Gray shale, sand, and limestone Sandstone and lumps of iron pyrite and some limestone Fine to coarse sandstone Red clastic series: Fine to coarse sandstone, with traces of red shale White and pink sands Red shale with some white sand Red and white sandstones Red shale White sand and some red shale Thick- ness. Feet. SO 15 12 95 25 43 20 110 15 60 20 70 20 5 30 160 40 30 20 15 40 235 Depth. Feet. 80 95 107 202 227 270 290 400 415 475 495 565 585 590 620 780 820 850 870 885 925 1,160 a Drilled in 18S5 by W. E. Swan; see references for the well at Mendota, above. WATER SUPPLIES FOR CITIES AND VILLAGES. Hastings. — This city stretches from the flood plain of the Missis- sippi to the summits of the morainic bluffs which stand to the west. The business part is built upon a shelf of the dolomites of the Prairie du Chien group, and the larger part of the residence district lies upon the broad terrace 100 to 120 feet above Mississippi River. Wells sunk upon this terrace have furnished the water supply for most of the inhabitants. Several deeper wells penetrating the sandstone forma- tions have also been drilled, among which may be mentioned the one at the Gardiner Mills, 850 feet in depth, the one at the state asylum, 830 feet in depth, and the one belonging to the Chicago, Milwaukee and St. Paul Railway Company, the section of which is given above. Recently a well 495 feet deep has been drilled for the city, and a sys- tem of public waterworks is being installed. South St. Paul. — The residence portion of South St. Paul is built upon the terrace that lies along the west side of Mississippi River at an elevation of 100 feet above the stream. Wells 165 feet in depth obtain an abundant supply of water from the Jordan sandstone, while a second great reservoir of underlying water occurs at a depth of 500 feet, and the most copious reservoir of all is tapped at a depth of 650 feet. All these water-bearing formations yield artesian supplies in abundant quantities. The section shown by the group of wells owned by Swift & Co. is given above. Here as elsewhere there is a question as to the permanence of the artesian supply. A few years 168 UNDERGROUND WATERS OF SOUTHERN MINNESOTA, ago the well belonging to the Union Rendering Company, which is a short distance from the plant of Swift & Co., flowed continuously at the surface. At the present time this well Hows intermittently. On Sundays there is always a flow, caused, no doubt, by the shutting down of some of the wells belonging to Swift & Co., the Stock Yards Company, and others. This indicates that the flow is not as good as formerly and that the diminution of head is due to the heavy demands made upon the deep water. The public supply, which is used by about one-halt' the people, is obtained from a flowing well 880 feet deep. Mendota. — In this village the supply is derived chiefly from com- paratively shallow wells. The St. Peter sandstone affords a reservoir of great capacity. The section of an artesian well drilled for the Chicago, Milwaukee and St. Paul Railway Company in 1884 is given above. The water from this well is rather hard but does not differ materially from the water drawn from the same formation in Min- neapolis and St. Paul. The well originally flowed 300 gallons a min- ute at 14 feet above the ground, but now barely Hows at the surface. SUMMARY AND ANALYSES. The largest and most permanent stores of water exist in the sand- stones, but supplies adequate for farm and domestic use can fre- quently be obtained at less depths from the surface deposits. In the valley of the Mississippi, and probably also in the valley of Cannon River. Hows can be obtained from the sandstone strata. When the red clastic series is encountered drilling should be discontinued. Mineral analyses of water in Dakota County. [Analyses in parts per million.] Glacial drift. St. Peter sand- stone. Shakopee t o Oneota dolo- mite. Jordan sand- stone. Depth feet . Silica (SiOa) Iron (Fe) Iron and aluminum oxides t, I AlsOs) Calcium (Ca.) Magnesium (Mg) Sodium and potassium iX;i-K*. Bicarbonate radicle (HCO s ; Sulphate radicle (SO*) Chlorine (Cl> Total solids 90 IS 1.6 143 10 4 69 i."4 $7 26 10 34$ 50 356 86 28 3.2 33$ SI 4.9 339 337 44 OS 354 333 17 303 269 70 352 100 "24"' 49 •23 4.4 222 ~13 5.3 263 35 01 •JO 358 DODGE COUNTY. Mineral analyses of water in Dakota County — Continued. 169 Dresbach sandstone and underlying shale. 16. Depth feet. Bilica (SiOs) Iron ( Fe) Iron and aluminum oxides (F2O3+ A1 2 3 ) Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+K) Bicarbonate radicle ( IICO3) Sulphate radicle (SO-i) Chlorine (CI) Total solids 2.1 52 17 12 2i,2 7 1.3 220 52 17 11 259 8.8 1.8 220 661 12 1,100 11 1,100 1.7 855 .9 Small. 39 58 414 94 65 580 04 28 185 195 80 308 773 85 32 215 425 80 200 897 75 30 100 313 147 92 020 52 14 0.4 258 0.0 12 254 475 13 26 16 244 45 12 288 1. Chicago, Milwaukee and St. Paul Railway well at Farminglon. August, 1890. 2. Chicago, Milwaukee and St. Paul Railway well at Farmington. November 1, 1901. 3. Chicago, Milwaukee and St. Paul Railway well at Farmington. November, 1900. 4. "Husausa water" well at Mendota. 5. Well of Magnus Brown at Farmington. November, 1900. 0. Chicago, Rock Island and Pacific Railway well at Inver Grove. 7. Swift &. Co. well at South St. Paul. 8. City well at Hastings; water taken at the depth of 140 feet. November, 1907. 9. Railway well at Mendota. August, 1890. 10. Railway well at Mendota. May, 1901. 11. Chicago, St. Paul, Minneapolis and Omaha Railway well at Mendota. April, 1901. 12. Chicago, Milwaukee and St. Paul Railway artesian well at Hastings. 1885. 13. Chicago, Milwaukee and St. Paul Railway well at Hastings. 1885. 14. Gardiner Mills well at Hastings. 15. Swift & Co. well at South St. Paul. 1905. 10. City well at Hastings. November, 1907. Analyses 8 and 10 were made by H. A. Whittaker, chemist, Minnesota state board of health. Analyses 3 and 5 were made for the United States Geological Survey by H. S. Spaulding. Analyses 1, 2, 9, and 10 were furnished by G. N. Prentiss, chemist, Chicago, Milwaukee and St. Paul Railway Company. Analy- sis 4 was made by Prof. C. F. Sidener, University of Minnesota. Analysis 6 was furnished by J. M. Brown, division engineer, Chicago, Rock Island and Pacific Railway Company. Analyses 7 and 15 were furnished by W. D. Richardson. Analysis 11 was furnished by G. M. Davidson, chemist, Chicago, St. Paul, Minne- apolis and Omaha Railway Company. Analysis 12 was made by Prof. J. A. Dodge, University of Minne- sota. Analysis 13 was made by J. P. Magnusson, University of Minnesota. DODGE COUNTY. By C. W. Hall and M. L. Fuller. SURFACE FEATURES. Much of the surface of Dodge County is very even, including large expanses in which there is hardly a noticeable irregularity. The highest land is along the southern edge, where the elevation above sea level reaches 1,350 feet and is generally more than 1,300 feet. In the northern portion most of the land stands between 1,200 and 1,300 feet but descends to 1,100 feet along the northern border. The country is so flat that the drainage is very poor, considerable areas being wet and marshy before they are artificially drained. The county is crossed by the two middle branches of Zumbro River; the southern branches head along the eastern border. In the south- western part there is a series of marshy depressions which at high water drain south into Cedar River. Most of the streams flow in shallow and somewhat indefinite channels, but the middle forks of the Zumbro near the eastern edge of the county have valleys 200 feet in depth, bordered in places by more or less precipitous banks. 170 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. SURFACE DEPOSITS. The surface deposits consist chiefly of glacial drift, which is a heterogeneous mixture of clay with pebbles and bowlders, locally containing interbedded layers of water-bearing sand and gravel. In most instances adequate supplies for domestic and farm purposes and even for small industries may be obtained. PALEOZOIC FORMATIONS. Beneath the surface deposits there is a succession of alternating beds of shale and limestone, the latter greatly predominating. At the southern margin of the county these are believed to embrace the Platteville limestone, Decorah shale, and Galena limestone, and also to include the lowest beds of the overlying Maquoketa shale, attaining a total thickness of several hundred feet. Toward the northeast this series of beds gradually thins out, the beds terminating successively from the top downward, until, in the valleys near the northeastern corner, underlying formations come to the surface. Below are given two well sections which illustrate this series in a general way. The first is the log of the well drilled for the Chicago Great Western Eailway Company in the village of Hayfield, near the southern extremity of the county. This well apparently passed through 390 feet of Ordovician strata without reaching the St. Peter sandstone. The second section is that of the well drilled for the same railway company at Dodge Center, which lies very near the geographic center of the county. In this section the Maquoketa shale appears to be absent. Well section at Hayfield. [Authority, J. J. Banks.] Glacial drift: Black soil Gravel Yellow clay Quicksand Blue clay Sand and clay Maquoketa, Galena, etc.: Limestone Shale Limestone Shale Thick- ness. Feet. 112 28 335 25 10 20 Depth. Feet. 2 4 12 15 127 155 490 515 525 545 DODGE COUNTY. 171 Well section at Dodge Center. [Authority, Mr. Knowlton, assistant chief engineer Chicago Great Western Railway Company.] Thick- ness. Depth. Glacial drift: Feet. Clay 28 Clay and quicksand 12 Blue clay and bowlders 44 Blue clay 28 Galena limestone and lower formations: Limestone and yellow clay 10 Limestone 102 "Hard rock" 52 Shale 73 " Hard rock" 17 White shale 11 Shale 82 Sandstone (probably St. Peter) : 31 Shale I 14 Feet. 40 84 112 122 224 276 349 366 377 459 490 504 Though the Galena and Platteville limestones contain no strong water-bearing beds, they yield supplies adequate for most ordinary purposes wherever they lie below the ground-water level, and espe- cially where they are immediately underlain by a bed of impervious shale. The St. Peter sandstone, which is about 100 feet thick, is exposed along the Zumbro Valley in the northeastern portion of the county, whence it dips southwestward and passes beneath the Platteville. Except near its outcrop it affords strong supplies of water. Beneath the St. Peter sandstone occurs a succession of limestones, shales, and sandstones. Several of the sandstones are important water-bearing beds. These include (1) the New Richmond, about 20 feet thick and 35 feet below the base of the St. Peter; (2) the Jordan, about 120 feet thick and 250 feet below the St. Peter; (3) the Dresbach, about 80 feet thick and 600 feet below the St. Peter. All these would yield copiously, but there is no. object in drilling to them so long as adequate supplies can be obtained from the St. Peter. WATER SUPPLIES FOR CITIES AND VILLAGES. Kasson. — The village of Kasson is provided with a public supply drawn from the St. Peter sandstone, which lies at a depth of about 300 feet and yields a safer and more permanent supply than any zone nearer the surface. West Concord. — In West Concord the water supply is virtually all derived from private wells. The public waterworks take water from a drilled w r ell 150 feet deep. 172 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Hayfield. — The stratigrapliic section near Hayfield is shown by the log of the railway well which is given above. Adequate water supplies are obtained at moderate depths from the glacial drift and the Galena and Platteville limestones. The public waterworks are sup- plied from .a well 377 feet deep, which ends in either the Galena or the Platteville. An analysis of the water is given in the accompanying table. SUMMARY AND ANALYSES. Except in the northeastern corner of the county, an adequate supply of water for ordinary purposes can be obtained at moderate depths from the glacial drift or the Galena and Platteville limestones. Owing to the unbroken surface and to the impervious strata beneath the water-bearing beds, the water usually stands relatively near the top of the wells. As is shown by the analyses, the water is all moderately hard. Whenever supplies are desired larger than can be derived from the drift or the Galena and Platteville limestones, drilling should be con- tinued to the St. Peter sandstone, which underlies virtually the entire county and is nowhere more than a few hundred feet below the surface. Nothing would generally be gained from drilling to still lower zones, for the water which they contain is fully as hard as that from the St. Peter and will rise no higher. Mineral analyses of water in Dodge County. [Analyses in parts per million.] Depth feet . Silica (Si0 2 ) Iron (Fe) Calcium (Ca) Magnesium (Ms) Sodium and potassium (Na+K) Bicarbonate radicle (HC0 3 ) Sulphate radicle (SO^ Chlorine (CD Total solids Glacial drift and Galena lime- stone. 120 14 92 34 5 447 5.9 4.5 140 12 73 21 7.5 2S9 240 21 114 35 8.5 440 5S 13 487 S.7 2.8 SS 28 11 234 39 13 326 St. Pe- ter sand- stone. 504 IS 1.3 SS 24 19 328 53 7.3 374 1. Chicago and Northwestern Railway well at Claremont. November, 1SS8. 2. Chicago and Northwestern Railway well at Kasson. June, 1SS9. 3. Chicago and Northwestern Railway well at Claremont. October, 1S90. 4. Well furnishing the public supply at Hayfield. November. 1900. 5. Chicago Great Western Railway well at bodge Center. November, 1900. Analyses 4 and 5 were made for the U. S. Geological Survey by H. S. Spaulding and Prof. W. S. Hen- drixsoii, respectively. Analyses 1, 2, and 3 were furnished by'G. M. Davidson, chemist Chicago and Northwestern Railway Company. UNDERGROUND WATERS OF SOUTHERN MINNESOTA. 173 FARIBAULT COUNTY. By C. W. Hall and M. L. Fuller. SURFACE FEATURES. Of the nine counties bordering on Iowa, Faribault occupies the middle place. The highest tracts within this county are the morainic belt about Elmore, on the southern border, where the elevation exceeds 1,250 feet above sea level on either side of Blue Earth River, and the morainic belt culminating in the Kiester Hills, which reach an elevation of more than 1,400 feet above sea level. The Kiester Hills and their extension stretch across the county with a northwest- southeast trend for 25 miles. The remainder of the county is strik- ingly level and plateau-like. According to Winchell the northern part is probably the bed of an ancient lake, known as Lake Minnesota. The surface drainage of Faribault County is effected through Blue Earth River and its tributaries. This stream rises in northern Iowa and flows almost due north across Faribault County, descending approximately 5 feet to the mile and occupying a valley which has been cut on an average to a depth of nearly 100 feet. The branches of the Blue Earth also lie in deeply grooved valleys cut into the plain that comprises a large proportion of the surface of the county. SURFACE DEPOSITS. Faribault County is everywhere deeply covered with glacial drift, the older rocks rarely occurring within 100 feet of the surface. The drift is a heterogeneous mixture of gray pebbly clay containing grav- elly or sandy layers that commonly yield good supplies of water. The morainal deposits, which have already been referred to, contain much gravel and sand and are marked by irregular rolling surfaces. Water is present in ample quantities, but on the elevations the ground-water level is relatively far below the surface. The glacial lake deposits, which were laid down when Lake Minnesota existed as a result of the obstruction of Minnesota River to the north, consist of ill-assorted sands and gravels about 10 feet thick, or too thin to be important as water bearers. The alluvium of Faribault County consists of silty sands and gravels deposited along the present streams. These deposits, wher- ever utilized, seem to afford sufficient water for all ordinary purposes. PALEOZOIC FORMATIONS. On the map of the Geological Survey of Iowa 6 the Mississippian limestone is indicated as reaching the state line opposite the western half of Faribault'County. As in this region the drift is thick and there has been little deep drilling, it is uncertain whether the Mississippian actually extends into Minnesota. It has never been recognized. a Final Rept. Geol. and Nat. Hist. Survey Minnesota, vol. 1, 1882, pp. 460-461. ?> Ann. Rept. Geol. Survey Iowa, vol. 17, 1906, PI. I. 174 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Devonian rocks are supposed to underlie the drift throughout a small area in the southwestern corner of the county. Fair supplies of water are generally obtained from the sandstone layer that is present locally in these beds. The Galena limestone, Decorah shale, and Platteville limestone, according to the record of the well in Freeborn, in the next county to the east, appear to have a combined thickness of about 300 feet. The limestones contain a large quantity of water fed from the over- lying drift. This water is given up generously to wells and in some instances is under sufficient head to be lifted nearly or quite to the surface. The St. Peter sandstone appears to lie immediately beneath the drift in an area northwest of a line extending approximately from Minnesota Lake through Blue Earth to Martin County. It is about 100 feet thick and consists of white or yellow sands commonly carry- ing large amounts of water which is available to wells penetrating through the overlying materials. The Prairie du Chien group (which when complete includes the Shakopee, New Richmond, and Oneota formations) is present imme- diately below the drift in the northwestern corner of the county. The rocks of this group here present consist of pink to buff magne- sian limestone, apparently characterized by joints and other fissures in the upper part, in which is found considerable water derived from the overlying drift. The New Richmond sandstone, a prominent water-bearing formation of this group in more easterly counties, has not been recognized. The Jordan sandstone is about 75 feet thick. It probably comes to the subglacial surface in the northwestern corner of the county, but dips southeastwardly beneath the Prairie du Chien group and thus underlies the whole county. It is reached by deep rock wells and affords large supplies of water, supplementing to an important degree the other water-bearing beds. Beneath the Jordan lie about 200 feet of St. Lawrence formation (limestone and shale), below which, in turn, is the Dresbach sand- stone and underlying shales, several hundred feet in thickness. Their water-bearing capacity here is similar to that which they have in other counties. The Dresbach sandstone could be depended on for supplies if the overlying beds should fail. The red clastic series and the granite beneath are not water bearing to an important degree. WELL RECORDS. Below are given the sections revealed by drilling in two localities of this county, together with the probable correlations of these sec- tions. The first is the log of the deep well sunk for the city of Blue Earth; the second is that of a boring in the village of Wells, FARIBAULT COUNTY. 175 Well section at Blue Earth. [Authority, G. W. Buswell.] Thick- ness. Depth. Glacial drift: Soil Yellow and blue clay Gray clay Sand and quicksand (water) Blue clay White sand (water) Gravel "Drift rock" Platteville and Galena (?): Limestone "Hard rock" St. Peter: Sandstone Prairie du Chien group: Limestone Jordan sandstone St. Lawrence formation (limestone and shale) Dresbach sandstone Shales Red shale and sand Granite Feet. 3 3 58 40 25 69 5 2 2 91 215 80 170 65 115 200 20 Feet. 3 6 64 104 129 198 203 205 285 287 378 593 673 843 908 1,023 1,223 1,243 Well section at Wells. [Authority, C. F. Loweth, civil engineer.' Thick- ness. Depth. Glacial drift Limestone (probably Galena) Sandstone (water) Blue shale Blue limestone White shale White limestone and sandstone (water) Green shale Sandstone (St. Peter) entered. Feet. 125 30 3 42 8 18 10 30 Feet. 125 155 158 200 208 226 236 266 UNDERGROUND WATER CONDITIONS. Wells. — As the ground-water level is generally near the surface there are many very shallow wells. These have not, however, proved to be entirely satisfactory either in their yield or in the quality of their water, and in many localities it has been necessary to sink wells to deeper water horizons. Some of these deeper wells obtain their supplies from sandy or gravelly layers in the lower por- tion of the drift, but many of them enter the underlying rock and draw from sandstone or limestone. The wells penetrating to the deep-lying, water-bearing sandstones have been sunk for industrial and public supplies and for the use of large stock farms. Head of the water. — Everywhere within the glacial drift the water is under pressure, the layers of bowlder clay furnishing a confining bed. Thus wherever wells are drilled the water rises, and many wells flow when casing is applied. The head of the water is derived from the morainal districts in the eastern and southern parts of the 176 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. county. The valleys of the larger streams have cut below the general level of the ground-water table, giving rise to springs from the upper beds and to flowing wells from the lower. Few of the flowing wells are more than 75 feet deep and many are less than 60 feet. They are situated along Blue Earth and Maple rivers and their tributaries, from the southern boundary of the county northward to the Blue Earth county line. In fact, it is possible to obtain flowing wells in nearly every valley in the county, the conditions being especially favorable in the deepest ones or those nearest the morainal ridges (PI. IV). Flows are also obtained on the lower ground in the vicinity of Wells, the head and supply apparently originating in the morainal ridge a few miles southwest of the village. WATER SUPPLIES FOR CITIES AND VILLAGES. Blue Earth. — The position and extent of the water-bearing layers beneath the city of Blue Earth are shown in the careful record given above of the well drilled in 1889. Several thick water-bearing beds occur in the glacial drift, which is here 200 feet deep. The lowest of these beds yields the largest supplies. Probably the best source of water for the city is the St. Peter sandstone, which is reached at 285 feet and is 90 feet thick or more. Below the St. Peter lies the Jordan sandstone, which is 80 feet thick. At the depth of 840 feet the Dres- bach sandstone is reached, and this, with the underlying shaly sand- stone, extends 180 feet downward. It furnishes large supplies but the water has not the quality of that from the St. Peter and Jordan. The deep city well was drilled to a depth of 1,243 feet in the hope of obtaining a flow. The water from the lower beds was somewhat salty and hard, and consequently the well was plugged at the top of the red sandstone and shale 200 feet above the bottom. Subse- quently the well filled still higher, and the supply of water gradually diminished while the population of the city increased. Hence, in 1904 a second well was sunk to the bottom of the Jordan sandstone. The new well is very near the old one and its log is essentially the same. During the drilling of the well any connection that might exist between the two was carefully noted. It was observed that in the new well, as in the old, water came freely from the deeper layers of glacial drift. When the St. Peter sandstone was entered, pumping at the old well lowered the supply in the new. The new well was cased to the top of the Jordan, or to a depth of about 590 feet. Sub- sequent operation, however, has convinced the authorities that the St. Peter is the stronger water producer of the two and steps are being taken to utilize both instead of confining the supply to the Jordan. The new well yields 350 gallons per minute. Wells. — The village of Wells stands on a prairie 1,150 feet above sea level. From this point the surface rises very gradually toward FAKIBAULT COUNTY. 177 the east and southeast, attaining an altitude considerably above that of the village. The water supply comes from two rather distinct zones — beds of sand and gravel in the glacial drift beneath the blue bowlder clay and sandstone strata at greater depths. (See the section given above.) In former years the water flowed several feet above the surface wherever a pipe was driven through the blue clay, and consequently it was a very simple matter to obtain water. As the quantity diminished and as citizens sought for further supplies, they found, on passing through the blue shale and limestone, that a white sandstone was reached and that this also yields generously. Analysis 11 gives the composition of the water from this zone. The supply for the waterworks is derived from two wells, one of which is 216 and the other 265 feet deep. About two-thirds of the inhabitants use the public water, and about 100,000 gallons of it is consumed daily. Winnebago. — At Winnebago the public supply is obtained from an 8-inch well, drilled to a depth of 266 feet, in which the water stands 6 feet below the surface. Supplementary to the public sup- ply, there are along the valley of Blue Earth River many flowing wells, the number of which has constantly increased from the settle- ment of the county to the present time. These flowing wells have always yielded water of a fairly uniform head and volume, being but little influenced either by abundant rains or by periods of drought. Their head is about 20 feet above the river. The following statement is made by Mr. Pierce: There are at present flowing wells all along Blue Earth River, the valley of which is about 60 to 80 feet lower than the surrounding country. The wells all flow when a depth of about 50 feet is reached, and should this vein fail a second one is reached at a depth of 75 feet. Several veins of nonrising water are drilled through before reaching these flows. The vein yielding the flow is invariably preceded by an extremely hard layer of blue clay, a genuine hardpan. The water is always located in a bed of coarse sand, which seems to have the same appearance and quality wherever penetrated. Elmore. — The public supply at Elmore is drawn from a well 110 feet deep, in which the water stands 8 feet below the surface. An analysis of the water from the railway well, which is 177 feet deep, is given in the accompanying table. Bricelyn. — The public supply of Bricelyn, which is used by about three-fourths of the people, is derived from a well 107 feet deep, in which the water stands 19 feet below the surface. The private wells vary greatly in depth. Many flowing wells have been obtained on the lower ground in the valley of Brush Creek, the one nearest Bricelyn being a half mile east of the village. Their average depth is about 75 feet, and they apparently procure their water from a bed of gravel that lies upon the Paleozoic of this part of the county. Easton. — The public supply at Easton is taken from a well 110 feet deep, in which the water stands virtually at the surface. Nearly 60920°— wsp 256—11 12 178 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. one-half the people use this supply, the water being furnished free of charge. Delavan. — The public supply at Delavan is taken from a well 473 feet deep, and is evidently drawn from the Jordan sandstone. The water stands 15 feet below the surface. The Chicago, Milwaukee' and St. Paul Railway Company uses a well that obtains its supply from a depth of 60 feet. An analysis of this water is given in the table. Kiester. — In the village of Kiester the public supply is drawn from a well 400 feet deep, but most of the inhabitants rely on private wells. Minnesota Lake. — The public supply at Minnesota Lake is obtained from a drilled well 185 feet deep. Most of the people have private wells. SUMMARY AND ANALYSES. The beds of sand and gravel in the deeper portion of the glacial drift afford a convenient and satisfactory source of water supply, and a large reserve is stored in the underlying rock formations, especially in the St. Peter, Jordan, and Dresbach sandstones. The section of the deep well at Blue Earth given above will serve to show the position ami approximate thickness of these formations. The water from the lower beds will not rise higher than that from the glacial drift, ami deep drilling for flowing wells is therefore not advised. Mineral analyses of trater in Faribault ( 'ounty. [Analyses in parts per million.] Glacial drift. Mix- ture. Paleozoic. Depth feet.. Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+lO Bicarbonate radicle (HCOs) Sulphate radicle (SOO- Chlorine (CI) Total solids Ill 37 34 404 91 1.5 520 90 33 11 431 30 1.5 3S6 96 35 15 461 43 1.0 426 323 47 496 102 3S 4.1 462 82 29 112 547 110 6.0 615 266 and 150 16S 53 97 402 491 5.9 1083 ■ 266 1S4 55 51 398 451 4.0 944 265 SI 29 95 522 91 2.9 558 1 . 240 179 50 9S 412 476 6.6 1.044 177 96 31 67 435 146 4.5 603 1. Railway well at Delavan. October 13, 1SSS. 2. Railway well at Huntley. October 10, 1SSS. 3. Railway well at Hunt lev. October 12. 1892. 4. Railway well at Huntley. December 27. 1899. :>. Railway well at Huntley (new source). September IS, 1901. 6. Railway well at Wells. 1892. 7. Mixture of water from the village and railway wells at Winnebago, 266 and 150 feet deep, respectively. April 8. 18s>;>. 8. Village well at Winnebago. April 8, 1S95. 9. Village well at Wells. February 19, 1S96. 10. City well at Blue Earth. 1S99. 11. Railway well at Elmore. Analyses 1. 2, 3, 4, 5, 6, 8, aud 9 were furnished by G. N. Prentiss, chemist Chicago, Milwaukee and St. Paul Railway Company. Analyses 7, 10. and 11 were furnished by G. M. Davidson, chemist Chicago and Northwestern Railway Company. UNDERGROUND WATERS OP SOUTHERN MINNESOTA. 179 FILLMORE COUNTY. By C. W. Hall and M. L. Fuller. SURFACE FEATURES. Fillmore County lies on what was originally a broad plateau. In the western and southern portions of the county the plateau character is still preserved, but in the northern and eastern parts the surface is very rugged, consisting of deep, sharp valleys separated by ridges with flat or gently rolling crests, the latter representing remnants of the original surface. The elevation of the plateau in the western half of the county is more than 1,300 feet above sea level, but to the east it descends to 1,250 feet, or about 550 to 600 feet above the Mississippi. In the western part of the county, where the plateau has not been dis- sected, it is fairly level, the flatness being due in part to the mantle of glacial drift that rests "upon it. Farther east there is little or no drift, but the upland surface is covered by a thin mantle of yellowish silt or loess, which, though it somewhat masks the inequalities of the rock surface, does not completely hide them, leaving a rather rolling sur- face. In the areas underlain by the Galena limestone and Decorah shale occasional basins or sink holes as well as mounds and low hills of the limestone occur. The principal valleys are those carved by Root River and its tribu- taries. In the harder rocks the valleys are narrow and canyon-like, but those in the softer rocks reach a width of a mile in places and con- tain extensive deposits of alluvium. The streams generally flow in rapids where they cross from harder to softer rocks, the change also being marked by terraces along the sides of the valleys. In some places bluffs and picturesque pinnacles border the valleys. SURFACE DEPOSITS. The surface deposits include alluvium, loess, and glacial drift. The alluvium of Fillmore County includes the gravels and sands deposited by Root River and its tributaries. The thickness of these deposits in some places is not known, but perhaps reaches 50. feet or more, the average probably being between 25 and 30 feet. They contain considerable water and usually yield ample supplies for domestic and farm purposes. The loess is a fine yellow loamy silt deposited over the uplands to a depth rarely exceeding 10 feet. It is unimportant as a water-bearing bed, but is of value owing to the fact that it collects rainfall and feeds it to the underlying rock. The glacial drift of Fillmore County consists chiefly of clay mixed with pebbles and bowlders, but locally it contains gravel and sand layers and in some places deposits of peat. It is found mainly in the western third of the county, where its greatest thickness is 100 feet. 180 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. In the eastern part it is very thin, in many places occurring onl} 7 in scattered patches. No water is found in these thin isolated deposits, but in the sand and gravel layers of the thick accumulations quan- tities sufficient for farm and domestic purposes occur. Certain dark clays, about 20 feet thick and underlain by several feet of water- bearing sandstone, have been thought to be Cretaceous, but there is little ground for this assumption. PALEOZOIC FORMATIONS. The Devonian rocks in Fillmore County consist of thin-bedded, even-grained, granular, yellow magnesian ami arenaceous limestones. They outcrop on the hilltops in the southwestern townships and have a total thickness of about 100 feet. They afford a small supply of water to shallow wells and give rise to occasional springs. The Maquoketa shale consists of calcareous and sandy shales aggre- gating about 80 feet in thickness. It outcrops along a - northwest- southeast line from a point near Hamilton on the western to Granger on the southern boundary. Because of their impervious character the shales contain practically no water, but intercept the water seeping through the overlying Devonian and residuary material, forming an important spring horizon. The Galena limestone, Decorah shale, and Platteville limestone outcrop in a number of bluffs bordering the headwaters of Root River. On the uplands the Galena limestone yields moderate quan- tities of water, but near the valley edges the water is largely lost by leakage. The supplies from the Platteville limestone are very small, as the water either escapes into the adjacent valleys where the forma- tion outcrops or sinks into the underlying St. Peter sandstone. The St. Peter sandstone outcrops in the upper parts of the bluffs bordering the principal streams and constitutes the surface rock on the upland areas in the eastern third of the county. It yields large supplies except near the valleys, where leakage has removed most of the water. The Shakopee dolomite is about 75 feet thick and is exposed in the bluffs bordering the principal streams in the eastern half of the county. Where it lies beneath the St. Peter sandstone it seems to hold up the water in that formation and makes shallow wells pos- sible. It carries some water in its bedding planes and sandy layers, but rarely affords supplies to wells. It gives rise to some springs along the valleys. The New Richmond sandstone is from 25 to 40 feet thick and out- crops in the principal valleys. It is not an important source of water supply. The Oneota dolomite is essentially a magnesian limestone, but in this county carries some green sand and occasionally shaly layers. FILLMORE COUNTY. 181 It is about 200 feet thick and is exposed in the valleys of Root River and its tributaries. It carries less water than the alluvium of the valleys and less than the overlying New Richmond. In itself it is not to be regarded as a source of water supply. The Jordan sandstone is about 100 feet thick. It outcrops in the Root River valley as far upstream as Lanesboro and also along several tributaries of this stream in the eastern portion of the county. Along its exposures in the valleys the supplies of water that it yields are usually small, but to the west where it passes under the uplands it carries large amounts of water and is the strongest water-bearing bed encountered. Here the water must, however, be raised several hundred feet to bring it to the surface. The St. Lawrence formation consists of about 175 feet of lime- stones, shales, and sandy beds, of which about 75 feet are exposed in the bottom of the Root River valley below Peterson. It carries a little water in the sandy beds, but because everywhere except in the valley mentioned it is overlain by the Jordan, which is a much stronger water bearer, it is of little importance as a source of supply. The Dresbach sandstone occurs about 125 feet below Root River at the eastern boundary of the county. It is an open porous sand- stone, saturated with water under considerable pressure, and yields supplies that rise nearly or quite to the surface of the river bottoms. In the valleys and near the edge of the uplands this sandstone affords the best source of water, but where it is deep below the surface, as in the western part of the county, there is no advantage in sinking to it, as equally satisfactory supplies can be obtained from the Jordan at a considerably less depth. Beneath the Dresbach sandstone are shales that carry little or no water. Below these shales is a sandstone that affords large volumes of water, but perhaps no more than the Dresbach sandstone, although it is under somewhat greater head. At still greater depths is the red clastic series, resting in turn on a granite foundation. UNDERGROUND WATER CONDITIONS. Head of the water. — Flowing wells are obtained in the valleys of Root River and its affluents as far upstream as Rushford. The water comes from the Dresbach and underlying sandstones and rises to 730 feet above sea level. It will not, however, rise to the surface in the upper parts of the valley, and on the uplands stands several hundred feet below the surface. Even in the highest portions of the county, the water from shallow horizons underlain by impervious formations may stand near the surface. The head of the drift wells varies with their position, depending on the altitude of the sur- rounding morainic masses and outwash plains. There are several flowing wells in T. 101 N., R. 13 W., near the state line, and others occur along upper Iowa River in Iowa. 182 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Quality of the water. — The water of the county is all moderately hard. It contains considerable quantities of calcium and mag- nesium and the bicarbonate radicle, but is not otherwise highly mineralized. See the analyses given in the accompanying table. Wells: — The wells of Fillmore County may be divided into several groups, the most important of which are (1) the shallow wells in glacial drift, (2) the shallow wells in alluvium, (3) the nonflowing rock wells, and (4) the flowing rock wells. The drift is not commonly a source of water except near the western border of the county, where it is 50 to 75 feet thick or more in places and usually carries considerable water at a level within easy reach of shallow open wells. Eastward across the county the drift decreases rapidly in thickness and yields but little water, so that it is necessary for wells to enter a rock formation. Except near the edge of the uplands, satisfactory supplies can be obtained at depths of 100 to 150 feet. Near the deepest valleys, however, the water is free to escape from the bluffs, and many of the upland wells must penetrate to depths of several hundred feet. It is not unusual for wells near the bluffs to go 250 to 350 feet for their supplies, and in some of them water is not obtained until the level of the valley bottom is reached. In general the wells on the south side of the valleys are deeper than those on the north side, because of the southward dip of the rocks. In the deep valleys many farm and village wells obtain their supplies from the alluvium at very shallow depths, but more satisfactory wells are procured in the valleys by drilling into the underlying sandstones, which are reached at moderate depths and from which the water rises nearly or quite to the surface. Springs. — In the deep valleys everywhere cut into the rock in the eastern portion of the county the water is free to escape and issues in numerous springs, some of them very large. These springs occur along lines that mark the upper surface of impervious shales and limestones. Many of the streams fed by such springs are capable of affording water power, and some of them are sources of supply for public waterworks. The strongest springs are said to be on the north side of the east-west valleys, the emergence of the water being facilitated by the southward dip of the rock. WATER SUPPLIES FOR CITIES AND VILLAGES. Lanesboro. — The village of Lanesboro obtains much of its supply from large springs issuing from the New Richmond sandstone and possibly from the Oneota dolomite and Jordan sandstone. The spring known locally as the City Spring is inclosed to form a cement- lined cistern about 15 by 30 feet in size, from which the water is pumped by an electric motor into the village system. Although only about 27,000 gallons is consumed daily, the spring is said to be FILLMORE COUNTY. 183 capable of yielding four times that amount. Analyses of the water are given in the tables (Nos. 4 and 5) . There is a large spring in the park near the village, the water of which apparently comes from the Jordan; another \\ miles south of the village is one of the largest springs in this locality and was formerly used for water power. These springs are interesting geologically as well as economically, because they indicate that large streams flow through deep-lying Paleozoic rocks. The drainage of the region is sufficient to produce such underground erosion that long cavernous passages have been carved out of the limestone. Where these springs are used for drinking supplies, the source should be sought out and guarded against pollution. Spring Valley. — The public supply at Spring Valley was at first ob- tained from springs issuing from the limestones and shales. This source soon became inadequate and the present supply is derived chiefly from a well 40 feet in diameter, sunk into the limestone and shale 18 feet below the surface. Preston. — One of the most notable springs of the county is that furnishing the Preston public supply. It issues from bedding planes at the base of the New Richmond sandstone and the top of the Oneota dolomite. It is only 2 feet above the level of the river and was formerly subject to overflow, but is now protected by cement walls. The water is collected in a cement cistern built down to the rock. The yield is said to be 250 gallons a minute, of which only about 30 gallons is required for the public supply. The flow is constant and independent of seasons. The water has but little permanent hard- ness and will not form much scale if heated before being admitted to boilers. Two analyses are given in the table. Rushford. — The first public supply for Rushford was installed about 1887, the water being obtained from a well sunk on the side of the bluff above the village. This well was used for a number of years, but, because of the expense of pumping, a new well 553 feet deep was sunk in 1901 on low ground in the center of the village, and flow- ing water was obtained. The flow shows certain puzzling fluctua- tions. When the barometric pressure is low, and usually in the spring, it discharges out of a pipe 1§ feet above the ground, but at other times the flow stops. The changes are irregular, however, and may have some other cause besides variations in barometric pressure. Chatfteld. — The village of Chatfield, which extends into Olmsted County, has a system of public waterworks deriving its supplies from wells sunk to the Jordan sandstone. Private wells drilled to depths of 65 to 100 feet procure an adequate supply. Harmony. — The public supply at Harmony comes from a well 220 feet deep, which ends in the St. Peter sandstone. The water is reported to stand 130 feet below the surface. It is used largely for domestic purposes. Wylcoff. — The public supply at Wykoff is derived from a well 600 feet deep, which has been pumped at the rate of 180 gallons a minute. 184 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. The water is reported to stand 300 feet below the surface. It is used by most of the people for domestic purposes. Fountain. — The first deep well in the vicinity of Fountain is said to have been sunk by William Herman. Its success showed the possibilities of deep wells, and accordingly others were drilled by private persons and by the municipality. The first village well was originally 6 inches in diameter and 376 feet deep, but later it was sunk to a depth of 585 feet and now obtains a good supply, the water rising within 340 feet of the surface. A street well was sunk to a depth of 376 feet and was pumped by a windmill and later by a gaso- line engine, but it finally failed. A new village well, sunk in 1906 to a depth of 608 feet, obtains water at depths of 90 feet and 370 feet and at the bottom. The records of the two deep wells are as follows: Section of the village wells at Fountain. [Authorities: Old well, W. G. Banks: new well, O. H. Case.] Old well. New well. Thick- ness. Depth. Thick- ness. Depth. Feet. 20 155 45 30 Feet. 20 175 220 250 Feet. 10 160 Feet. 10 Galena, Decorah, and Platteville: 170 30 200 St. Peter sandstone 90 30 40 ISO 340 370 410 590 90 290 85 375 New Richmond sandstone 35 410 190 Jordan sandstone (entered). The large springs from which Fountain derives its name are a mile or more northwest of the village and issue at a level 147 feet lower than the general level of the village. The water comes in large volume from solution crevices in the limestone immediately above the shales (see the above sections). At one time it was lifted by a ram to the village, but the springs were abandoned because of the muddiness of the water after storms, evidently due to the earth entering the underground passages through the sinks in the vicinity. Since these sink holes are often made the receptacles of refuse, the waters are liable to pollution, and the village did well to abandon its supply. Mabel.^-The public supply at Mabel is here drawn from a well 140 feet deep, in which the water rises within 40 feet of the surface. A majority of the people use private wells. Canton. — In the village of Canton there is a well 240 feet deep. The stock yards are supplied from a well reported to be 318 feet deep. These wells apparently derive their water from the New Richmond and Jordan sandstones, respectively. FILLMORE COUNTY. 185 SUMMARY AND ANALYSES. The most reliable supplies in Fillmore County are derived from the deep sandstone formations. The water from these beds stands at a level far below the upland surface, but rises nearly to the level of the deepest valleys and near Rushford produces flows. Many satisfac- tory wells for farm and domestic supplies are obtained from the sur- face deposits and from the rock formations near the surface. These wells have an advantage over those going to the deep sandstones both in depth and in head. The waters from all the horizons utilized are similar in chemical composition. They contain rather large amounts of calcium and magnesium and the bicarbonate radicle, but little other mineral matter. Mineral analyses of water in Fillmore County. [Analyses in parts per million.] Root River. Springs. Depth feet. Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+Kj Bicarbonate radicle ( HC03) Sulphate radicle (SO-0 Chlorine (CI) Total solids 20 6.5 290 7.2 .0 242 74 21 7.5 334 10 1.0 278 62 20 9.5 303 8 1.6 257 83 26 10 385 16 326 73 24 3. 318 16 24 286 60 21 4.5 251 93 2 248 78 25 11 240 38 79 18 4.1 314 8.1 25 286 St. Peter and New Richmond sandstones. 15. 16. 18. Jordan sandstone. Depth feet. Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+K). Bicarbonate radicle (HC0 3 ) Sulphate radicle (SO4) Chlorine (CI) Total solids 476 47 456 341 26 67 312 310 280 10 3 241 60 7.1 304 28 295 190 90 32 12 460 5.9 4.5 389 318 88 30 415 6.5 9.1 352 389 79 24 6.5 350 20 1.2 305 585 '82 33 3.8 342 23 1.1 301 600 76 23 334 22 4 296 1. Water from Root River at Lanesboro. October, 1892. 2. Water from Root River at Lanesboro. 1903. 3. Water from Root River at Preston. October, 1892. 4. Spring at Lanesboro. August, 1903. 5. Spring at Lanesboro. December, 1906. 6. Spring at Spring Valley. October, 1906. 7. Spring at Preston. December, 1899. 8. Spring at Preston. 1906. 9. Chicago, Milwaukee and St. Paul Railway well at Rushford. November, 1892. 10. Chicago, Milwaukee and St. Paul Railway well at Spring Valley. August, 1888. 11 . Chicago, Milwaukee and St. Paul Railway well at Spring Valley. December, 1899. 12. Chicago, Milwaukee and St. Paul Railway well at Mabel. January, 1889. 13. Chicago, Milwaukee and St. Paul Railway well at Preston. Sept. 1892. 14. Chicago, Milwaukee and St. Paul Railway well at Mabel. September, 1892. 15. Chicago, Milwaukee and St. Paul Railway well at Canton. September, 1892. 16. Village well at Haimony. January, 1889. 17. Well at the stock yards in Canton. December, 1888. 18. Chicago, Milwaukee and St. Paul Railway well at Fountain. December, 1895. 19. Village well at Fountain. December, 1890. 20. Village well at Fountain. February, 1907. Analyses 5, 6, and 8 were made for the United States Geological Survey by H. S. Spaulding; all the others were furnished by G. N. Prentiss, chemist Chicago, Milwaukee and St. Paul Railway Company. 186 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. FREEBORN COUNTY. By C. W. II aii. and M. L. Fxn i er. SURFACE FEATURES. Five bo rn County lies upon the plateau that forms the southeastern portion o( the State. Its topography is very simple. The extremes of altitude are between about 1,150 feet above sea level in the north- western corner ami about 1,350 feet on the morainic summits in the central portion. Its average altitude is not less than 1,250 feet. Two well-defined belts o( morainic mounds extend from north to south across the county, one of them through the eastern part ami the other ami larger belt through the west-central part. Owing - to the irregular surface caused by the deposition of these belts, a number of lakes have been formed which lie in the depressions ami mark the ground-water level in this part of the county. Along the eastern ami western borders ami on the smooth stretch between the morainic districts the land is relatively level and has an altitude between 1,150 and 1,250 feet, with very little variation. The streams which carry off the surface drainage of the county flow partly southward across Iowa to Mississippi River ami partly north- westward across Faribault ami "Waseca counties into Minnesota River. The west-central morainic belt forms the divide that sepa- rates these waters. There are no streams of considerable size within the county ami many hundred square miles show no definite drainage valley. SURFACE DEPOSITS. The glacial drift varies from 75 to more than 200 feet in thickness. Along the eastern bonier of the county wells indicate a thickness of 100 feet, which increases gradually westward ami northward to more than 200 feet, the last-named thickness being reported near Hartland ami near Clarks Grove. The two broad north-south morainic belts are composed of diversified material, including very characteristic drift masses of bowldery gravel and sand, extensive stretches of stratified gravels and sands, and not uncommonly an excellent brick clay, quite free from the bowlders so common in the ordinary drift. Water abounds in these morainic accumulations, but owing to the diversified character of the material the supply is far from uniform. Modified drift constitutes the surficial deposit of the level tracts between the morainic ridges. The stratified character of this mate- rial is frequently seen in the dug wells, which are 10 to 50 feet deep. Much of the material is in the form of a lake deposit, but doubtless it was mostly formed as an out wash from the melting ice and accumu- lating moraines. FREEBORN COUNTY. 18*7 CRETACEOUS DEPOSITS (?). The presence of Cretaceous rocks has repeatedly been announced for Freeborn County , a but a review of the records shown by the wells reported fails to make clear the presence of deposits of this period. Fragments of "coal" or wood in advanced stages of transformation to coal have frequently been dug up, but nowhere has there been reported a deposit that may positively be referred to Cretaceous age. In Blue Earth and other counties, particularly Chisago, interglacial peat beds have been discovered ; fragments of wood may come from these, and the fragments of lignite or "coal" may easily have been brought in the glacial drift from the counties lying farther west, where such deposits are known to occur. PALEOZOIC FORMATIONS. The limestone referred to the Devonian is an extension westward of the formation seen at the surface at and near Austin. It occurs beneath about one-half of the county, with its greatest thickness in the southeastern corner. Associated with it is a belt of water- bearing sandstone which may also belong to the Devonian or may prove to be an arenaceous layer of the earlier period represented by the Galena, Decorah, and Platteville formations. Good supplies of water have been drawn from this limestone through a number of wells drilled into it in the southeastern part of the county. Beneath the drift in the northwestern quarter of the county occurs the buff magnesian Galena limestone, underlain by a thin bed of Decorah shale and 25 or 30 feet of Platteville limestone. The total thickness of these formations, as indicated by the Freeborn well, appears to be more than 300 feet. Little or no water is found in the shale, but in general the limestones will yield enough for domestic and farm purposes and occasionally, where the upper surface is broken and fissured, enough for industrial and small public supplies. The St. Peter sandstone underlies the Platteville limestone through- out the county and is generally 600 to 700 feet below the surface. Its thickness is believed to be about 140 feet, and it is usually saturated with water under considerable pressure, the supplies entering the wells freely and affording quantities usually sufficient for all purposes. Beneath the St. Peter sandstone is a succession of limestones, sand- stones, and shales, reaching a depth of many hundred feet. All the sandstones, except those of the red clastic series, contain large amounts of water which would be yielded to deep wells penetrating them. In general, however, the supplies are no greater than those from the St. Peter, and hence there has beenusuallyno advantage in sinking to them. a Ann. Rept. Geol. and Nat. Hist. Survey Minnesota, 1874; Final Rept., vol. 1, 1882, pp. 382-385, etc 1SS UNDERGROUND WATERS OF SOUTHERN MINNESOTA. l T Nl>F.KOKOVNO WATEK CONDITIONS. Wells. —Owing io the fact that the entire surface of the county is covered with drift, rarely loss than LOO and at many points more than 200 feet thick, by far the greater number of the wells obtain their supplies from this material, though many have also been sunk io the underlying rock formations. The wells may be grouped in four general classes — P shallow wells in glacial drift, (2) deeper wells in drift. (3) wells sunk to the glacial-subglacial contact /one. and (4) wells entering the Paleozoic rocks. The wells of the first class seldom exceed 30 feet in depth ami obtain their water from thin, gravelly layers in the upper portion of the drift. The water at this horizon is more liable io pollution from the surface seepage than any of the deeper supplies, and it often fails in dry seasons. For both these reasons this source of water is gen- erally less desirable than the deeper formations. Most wells of the second class are 25 to 75 feet deep ami penetrate a considerable thickness o( yellow and blue drift. They obtain their supplies from interbedded gravelly layers at varying depths. Being of the tightly cased tubular type and carried through impervious clays, these wells generally are freer from danger of contamination than those in the first class. The water is commonly harder but more, palatable than that of the shallow wells. In some places, however, where much ancient and slowly decomposing organic material occurs in the drift, the waters may taste strongly of iron and sulphur derived from the lignite, black clay, etc. The third class of wells — those entering the materials of difficult stratigraphic assignment between the drift ami the underlying hard rock — commonly obtain abundant water. The supply is. however, very often of the ferruginous or sulphurous character described above. Not uncommonly wells sunk into the upper layers of the Paleozoic limestones gather their waters from this contact zone. In such wells the limestone serves as a reservoir for collecting supplies. Most of the wells of the fourth class obtain their water from the formations lying only a short distance below the glacial drift. Thus near the northeastern corner a number are supplied from the Devonian sandstone. But the deeper wells pass through the upper formations and reach the St. Peter or sandstones at still lower levels. Flowing areas. — Flowing wells are found in the lowlands about Geneva. Albert Pea. and Glenville, in Riceland Township, and else- where. The water is obtained in part from the base of the drift and in part from the upper portion of the underlying Paleozoic formations. The head appears to come from the adjacent moraines. Springs. — The surface of Freeborn County is in general undissected and springs are accordingly scarce. Nevertheless, a considerable num- ber of small springs issue along the streams and at the foot of the morainal hills, where they are used for stock purposes. FREEBORN COUNTY. 189 WATER SUPPLIES FOR CITIES AND VILLAGES. Albert Lea. — The public supply at Albert Lea is used by approxi- mately one-half the people, and it is estimated that 200,000 gallons of water are consumed daily. The supply is obtained from two drilled wells. One is 448 feet deep and ends in the Galena; the other is 660 feet deep and reaches the St. Peter sandstone. The water is under sufficient head to rise to the surface, and the maximum yield is very large. It is reported that the wells under test have yielded at the rate of 1,000 gallons a minute. Al/len. — The well that furnishes the public supply at Alden is j!15 feet deep and ends in the Galena. About one-fourth of the people use the water from this well, and nearly '20,000 gallons are consumed daily. Hartland. — The public waterworks in the village of Ilartland are supplied from a well that ends in the Galena limestone at a depth of about 300 feet. Emmons. — The waterworks at Emmons are supplied by a drilled well 160 feet deep. Virtually all the people depend on private wells. SUMMARY AND ANALYSES. The glacial drift furnishes the most accessible and largely utilized source of water supply in Freeborn County. Several strong water- bearing beds, however, lie at greater depths and afford a large reserve that can be tapped by deep wells anywhere within the limits of the county. Mineral analyses of 'water in Freeborn County. [Analyses in parts per million.] Depth Calcium (Ca) Magnesium (Mg) Sodium and potassium (N'a+K;. Bicarbonate radicle < I [CO3) Sulphate radicle (SO4) Chlorine (CI) Total solids .feet. Glacial drift. 1. 2. 3. 4. 5. 14 18 20 m> 643 151 98 110 100 99 42 26 33 30 30 19 33 Hi 22 12 398 445 394 496 455 164 52 98 18 27 65 25 1.5 639 435 481 i 423 St. Peter sand- stone. 1. Chicago, Milwaukee and St. Paul Railway well at Albert Lea. 1897. 2. Chicago, Rock Island and Pacific Railway well at Albert Lea. 3. Chicago, Milwaukee and St. Paul Railway well at Albert Lea (former sunply;. 4. City well at Albert Lea. 1892. 5. Minneapolis and St. Louis Railroad well at Albert Lea. 1903. 1892. 190 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. GOODHUE COUNTY. By C. W. Hall and M. L. Fuller. SURFACE FEATURES. Like other counties bordering on Mississippi River Goodhue County has a surface consisting of relatively level upland tracts separated by the deep valleys of the numerous tributaries of that stream. These upland areas, which are a part of a once continuous plateau, range in elevation from 1,000 feet above sea level in the north to 1,100 feet in the center, and 1,150 feet in the south, where they stand 450 feet or more above the Mississippi. They preserve the flat or gently rolling aspect characteristic of the original plateau surface, and are also marked here and there by sudden variations of level where the rocks change in hardness. The highest elevations are in the areas of the harder and more resistant Galena and Platte- ville limestones. The irregularities of the uplands are subdued in the east by a coating of loess, and in the west by the glacial drift. The county is crossed in its northern part by Cannon River. The bed of this stream is 250 to 300 feet below the uplands. Along the south side of the county the north branch of Zumbro River has eroded a channel 100 to 150 feet deep. Besides these there are numerous short tributaries of the Mississippi occupying ravines or valleys, which in their lower portions may be so much as 400 feet below the adjacent uplands. Except a few of these ravines, the valleys of Goodhue County are not canyon-like, and the streams are so numerous that the upland tracts are generally small. Along Cannon River, and also along the Mississippi, both above and below the mouth of the Cannon, are found series of terraces, some of which are of considerable extent. They represent the action of the waters from the glaciers that once occupied the region and bear evidence of some interesting features in the glacial and post- glacial history of the State. SURFACE DEPOSITS. The surface deposits of Goodhue County include alluvium, terrace gravels, loess, and glacial drift. The alluvium, consisting of stratified, loamy gravel, sand, and silt deposited by the streams, has an unknown thickness, but prob- ably is at most 150 feet thick. Considerable amounts of water, derived from rainfall, from downward percolation from the streams, and from leakage from the hillsides, occur in the pores of the deposit and are available to wells of moderate depth in amounts sufficient for domestic, farm, or small industrial purposes. Along Mississippi River within this county are some of the most notable alluvial beds the State affords. GOODHUE COUNTY. 191 Owing to recent erosion by the streams their ancient flood plains are now seen only as narrow shelves or terraces. Water is readily absorbed by the gravels and the sands of these terraces, but because of their exposed position this water is quickly drained away; hence the terraces are not generally satisfactory sources of supply unless the wells penetrate to a point below the level of the adjacent streams. The loess is a yellow unstratified silt reaching 15 feet or more in thickness. It is found mainly on the flat-crested ridges between tke streams, being elsewhere largely removed by subsequent erosion. Owing to the thinness of the deposit it is seldom a source of water supply, but is important because it absorbs quickly the water falling on its surface and feeds it to the underlying rock. The glacial drift of Goodhue County is in some places 50 to 100 feet thick and is predominantly of the clayey type, weathered to a yellow color for 10 to 20 feet below the surface. Locally it is some- what gravelly, especially at its base, thus affording good facilities for the storage of water. The drift-covered area occupies a strip several miles long from the northern point of the county southwest- ward to a point south of Dennison, where its boundary turns south- eastward, passing near Zumbrota and Pine Island. Much discussion has been aroused by certain beds of clay found in the central portion of Goodhue County, the best-known exposure of which is in T. 112 N., R. 15 W. It is a fine blue clay of uniform texture and of so excellent a quality that it is used in a large manu- factory of tile and earthenware at Red Wing. It has all the char- acters of the Cretaceous as known in identified localities and has accordingly been considered to be of Cretaceous age. Inspection of the beds, made possible by quarrying operations, has shown, however, that glacial gravels lie beneath the clay, and this situation leads to the conviction that the material, though derived from Cretaceous beds elsewhere, is stratigraphically a mass of glacial drift. ROCK FORMATIONS. . Rocks are exposed in the bluffs along Mississippi River and its larger tributaries in practically continuous outcrops across the county. On the crest of the ridges between the streams, however, rock rarely shows at the surface because of the mantle of loess. Farther west the rock formations are still more deeply buried by glacial drift. The Galena, Decorah, and Platteville formations, with a thickness varying from 50 to 75 feet, occur beneath the highest lands in the southwestern part of the county, but are of little value as a source of water. oSardeson, F. W., The so-called Cretaceous deposits in southeastern Minnesota: Jour. Geology, vol. 6, 1898, pp. 679-691. 192 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. The St. Peter sandstone is about 150 feet thick and outcrops along the rim of the uplands bordering the Cannon and Mississippi river valleys. In the eastern part of the county it underlies the upland flats between the streams, from which it passes beneath the glacial deposits to the west, appearing at the surface only in deep valleys. Where deeply buried it carries considerable water and affords good supplies to wells that pass through the overlying drift and limestone, but along its outcrops its supplies are much smaller, owing to the escape of the water into the adjacent valleys. The Shakopee dolomite, which is about 25 to 40 feet thick, out- crops along the edge of the bluffs of Cannon and Mississippi rivers and their tributaries. Its contact with the overlying St. Peter affords a notable spring line. Certain sandy layers afford a little water, but its significance is in its relation to the two sandstones between which it lies. The New Richmond sandstone is about 30 feet thick and outcrops between the Shakopee and Oneota dolomites in the river bluffs. It carries considerable water and at some distance from the valleys may furnish supplementary supplies of importance. Beneath the drift area, however, it is of slight importance as a water bearer, because the St. Peter, which also is here under cover, furnishes more copious supplies. The Oneota dolomite is similar to the Shakopee in all its rock char- acters but reaches a thickness of 150 feet in its outcrops along Missis- sippi and Cannon rivers. It carries some water in joints and bedding planes, but the yield is much less than from the overlying New Richmond sandstone, and hence it is of little importance as a source of supplies. Wells starting in the Oneota should be carried through it to the Jordan sandstone. The Jordan sandstone is about 90 feet thick, outcropping in the lower bluffs of the deepest valleys in the eastern part of the county. From its outcrop it dips slightly southwestward, underlying the entire county in that direction. Near its outcrop it will furnish only small supplies, but on the uplands, at a distance from the valleys, it will yield large supplies of good quality to deep wells. The St. Lawrence formation consists of shale and dolomite with some sandstone and green sand, the whole having a thickness of about 140 feet. It occurs in the lower portions of the bluffs and beneath the alluvium of the Mississippi Valley and its large tribu- taries. It carries a little water, especially in its sandy layers, but because of the compact texture of the formation as a whole the vol- ume is much less, than in the overlying Jordan or in the underlying Dresbach sandstone, and hence it is rarely to be considered as a source of supply. GOODHUE COUNTY. 193 The Dresbach is a white to gray mica-bearing sandstone with some shale. It is about 85 feet thick and lies entirely below the level of Mississippi River. It carries large amounts of water in its porous, sandy layers, and its supplies are available to deep wells at all points in the county. The water is under considerable artesian pressure and will rise to the level of the Mississippi flood plain or slightly higher. The shales which underlie the Dresbach sandstone are present throughout the county and will yield large supplies of water. In the Mississippi River valley the water is usually under sufficient head to flow at the surface. Beneath these shales occurs the red clastic series, consisting of a succession of red sandstones, quartzites, and shales, the total thickness of which varies more than that of any stratified formation of southeastern Minnesota. This variation is probably due to the uneven granite surface upon which the rocks were laid. Experience has shown that when these red rocks are reached little additional water may be expected, and the water which they do contain is very hard and rich in sodium chloride. Granite has been reported at Red Wing at a depth of a little more than 200 feet, but this report has not been verified. UNDERGROUND WATER CONDITIONS. Head of the water. — In the southwestern portion of the county the water stands but little below the upland surface, many shallow wells being only 15 to 30 feet deep, but toward Mississippi and Cannon rivers the ground- water table gradually drops and adjusts itself to the drainage level of the deep valleys. Along the entire length of Mississippi and Cannon rivers and many tributary streams in this county flows of good volume are obtained from the Dresbach sandstone. This artesian supply has been util- ized constantly since 1881, and the demands upon it have steadily increased, not only in Red Wing but at various places throughout the length of the valley; as a result the flow has been slowly dimin- ishing. Quality of the water. — So far as has been determined by the inves- tigation the water from all horizons is hard but wholesome. The water from the red clastic series is especially hard and high in chlo- rine content. Springs. — Numerous springs occur along the contact zone of the several Paleozoic formations and afford copious supplies of whole- some water for dairying and locally for power. These springs flow from different horizons in different parts of the county. In the high area near the southwestern corner the top of the Galena limestone 60920°— wsp 256—11 13 194 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. affords an excellent base along which the water makes its way within the glacial drift, loess, and residuary material that together make up the surface covering. The top of the Shakopee affords another horizon of springs where the supplies are collected from the extensive St. Peter sandstone. From the highest exposures of the Shakopee to the lowest Oneota there are no well-defined spring hori- zons, but at the bottom of the Jordan sandstone there is another spring zone of notable proportions, the underlying shaly beds of the St. Lawrence formation giving the necessary floor along which the waters of the sandstone creep to the valleys. WATER SUPPLIES FOR CITIES AND VILLAGES. Red Wing. — The lower portion of the city of Red Wing is built on the Mississippi flood plain, which is more than a mile in greatest width. The water supply from the alluvium is copious, but because of seepage from higher ground it has become so contaminated that it is unsafe for human use. The underlying rock, which yields large supplies of water, is reached at depths varying up to 130 feet. At Red Wing and in its immediate vicinity the artesian zones are heavily drawn upon. The first flowing well was drilled for the Chicago, Milwaukee and St. Paul Railway Company. It reached a depth of 500 feet, passing through the shales of the St. Lawrence formation, the Dresbach sandstone, and underlying shales, and pene- trating the red rock. Water rose under a pressure of 40 pounds per square inch at the surface and maintained an excellent supply until the casing became corroded and the well clogged. A second well drilled for the railway company yielded equally good supplies. Among other firms utilizing artesian waters are the following: Sim- mons Milling Company, G. A. Carlson, Lagrange Milling Company, Red Wing Malting Company, Minnesota Malting Company, Red Wing Brewing Company, Minnesota Stoneware Company, Red Wing Gas Company, and Chicago Great Western Railway Company. There are also two flowing wells at the State Training School, 2 miles from the city. The strongest well at present is probably that of the Chicago Great Western Railway Company, the water from which rose 28 feet above the surface. The flows of some of the wells have been very large. In the Chicago, Milwaukee and St. Paul Railway well, for example, W. E. Swan, the driller, reported the original flow at 800 gallons a minute and the head at 75 feet above the surface. The first flow was struck at 191 feet, and the yield increased until the red rock was reached. Formerly the flowing wells were used without pumping, but at present some of them are pumped. The diminished oWinchell, N. H., Final Rept. Geol. and Nat. Hist. Survey Minnesota, vol. 2, 1885, pp. 20, 21. GOODHUE COUNTY. 195 yield is due to local interference from the drilling of many wells in the same vicinity and, in some of the older wells, to the corroding of the casing. Analyses of the water from several of the flowing wells are given in the accompanying table. The following record of the strata underlying Red Wing is compiled from drillers' notes and data published by the Geological Survey of Minnesota : General well section at Red Wing. a Thick- ness. Depth. Jordan sandstone b St. Lawrence formation: Sandy shale , Blue shale Sandstone Blue shale Alternating sandstone and limestone. .. Dresbach sandstone and underlying shales: White sandstone Shale and shaly sandstone Red shale, etc Granite (entered). Feet. 70 10 50 10 30 45 50 250 9 Feet. 35 85 95 125 170 220 470 479 a Winchell, N. H., Thirteenth Ann. Rept. Geol. and Nat. Hist. Survey Minnesota, 1884, pp. 57-58. b This formation and the upper layers of the St. Lawrence occur only in wells located in the upper portion of the city. The public supply is taken from Mississippi River. Although origi- nally intended for fire protection, it has become generally installed in the business part of the city for ordinary use. The residence dis- tricts still use shallow wells and cisterns to a large extent. Without nitration the river water is not fit for domestic supplies because of the large communities located upon the banks farther upstream. Likewise the water afforded by shallow wells is here, as everywhere, soon polluted. In order to have a safe supply, it is necessary to utilize deep artesian waters or else install an efficient plant for filter- ing the river water. The following table shows the mineral quality of the water from the various sources : Composition of water at Red Wing. Mississippi River. Shallow wells. Deep wells. Hardness: Temporary 6.2 5.2 8.7 5.5 5.6 3.3 11.4 12.1 9.2 Residue: Fixed 147.2 52.0 512.8 180.3 208 Volatile 67.3 199.2 693.1 275.3 196 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Cannon Falte. — The public supply at Cannon Falls is derived from a flowing well which is 270 feet deep and taps the Jordan sandstone. The following is the approximate stratigraphic section for the vicinity of Cannon Falls : General section of deep wells at Cannon Falls. Platteville limestone (on tops of surrounding hills"). St. Peter sandstone Shakopee dolomite New Richmond sandstone Oneota dolomite Jordan sandstone Thirk- ness. Feet. ■j;. 150 36 8 150 Depth. Feet. 25 175 210 218 368 448 Kenyon. — The public supply for the village of Kenyon is obtained from a shallow well in the weathered and fissured limestone. The first strong water-bearing formation beneath this locality is the St. Peter sandstone, which lies immediately under the Platteville lime- stone, at a depth of not more than 125 feet. Approximately 200 feet below the bottom of the St. Peter the top of the Jordan sandstone, the second great water-bearing formation of this region, will be reached. Zumbrota. — The public supply at Zumbrota is obtained from a well 210 feet deep. Most of the people use shallow private wells. Pine Island. — The public supply at Pine Island is derived from a well 156 feet deep, which has been tested at 100 gallons a minute. This water is used by about two-thirds of the people of the village. Goodhue. — The public supply at Goodhue is derived from a well 10 inches in diameter and 275 feet deep, which has been tested at 300 gallons a minute. The water is used by nearly all the people for domestic purposes. SUMMARY AND ANALYSES. Several sandstone formations will yield large and permanent sup- plies of moderately hard water in Goodhue Comity. In the deepest valleys flows are obtained from the Dresbach sandstone and under- lying beds, but on the uplands the water from the lowest horizons stands far below the surface. The red clastic series should never be penetrated, as it will furnish only meager amounts of highly mineral- ized water. GOODHUE COUNTY. 197 Mineral analyses of water in Goodhue County. [Analyses in parts per million.] Springs. St. Peter and New Richmond sandstone. Jordan sand- stone. Depth feet. Silica (Si0 2 ) Iron and aluminum oxides (F2O3+AI2O3) Iron (Fe) Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+K) Bicarbonate radicle (HCO3) Sulphate radicle (SCn) Chlorine (CI) Nitrate radicle (N0 3 ) Total solids 97 28 20 442 20 14 30 20 1.7 40 8.4 270 15 7 210 21 2.9 96 27 13 292 24 18 .15 79 27 16 322 52 18 2.3 544 116 28 18 296 100 33 70 23 5.2 308 34 4.8 72 20 7.4 343 24 1.0 74 32 4 313 23 1.5 514 303 306 277 Dresbach sandstone and underlying shales. 14. Depth feet. . Silica (Si0 2 ) Iron and aluminum oxides (F2O3+AI2 3 ) Iron (Fe) Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+K) Bicarbonate radicle (HCO3) Sulphate radicle (SO*) Chlorine (CI) Nitrate radicle (NO3) Total solids 225 9.0 300 3.6 325 2.2 9.5 1.6 62 17 22 326 18 5.0 Trace. 312 66 30 46 275 74 61 147 25 49l" 65 1.0 483 1.5 62 18 29 310 21 28 Trace. 331 450 4.2 4.50 0.0 450 10 1,018 2.5 9.9 54 23 74 319 6.5 132 43 281 464 240 343 64 29 72 306 40 101 406 1,277 52 14 57 264 22 60 Trace. 361 61 37 9.0 370 10 6.7 315 1. Spring at the bed of Cannon River at Cannon Falls. 1902. 2. Spring at Vasa. 1902. 3. Experimental well at Red Wing, situated on opposite side of Chicago, Milwaukee and St. Paul Railway tracks from the pumping station. 4. Village well at Kenyon. November 23, 1906. 5. Railwav well at Cannon Falls. December 1, 1882. 6. City well at Cannon Falls. November 23, 1906. 7. Village well at Zumbrota. November 19, 1906. 8. Artesian well at the St. James Hotel in Red Wing. 9. Artesian well of the J. H. Rich Sewerpipe Company at Red AVing. June 11, 1896. 10. Minnesota Stoneware Company well at Red Wing. January 28, 1896. 11. Artesian well at the Red Wing brewery. 12. Railway well at Red Wing. 1891. 13. Well at the poor farm near Red Wing. 1902. 14. Artesian well of the Red Wing Sewerpipe Company. May 11, 1898. 15. Artesian well at the Chicago, Milwaukee and St. Paul Railway station, Red AVing. 16. AVell at the state training school in Red AA r ing. 1899. Analyses 4, 0, and 7 were made for the United States Geological Survey by H. S. Spaulding. Analyses 3, 8, 11, and 1.5 were made by M. G. Roberts, chemist Minnesota state board of health. Analyses 1, 2, and 13 were made by J. P. Maghusson, chemist University of Minnesota. Analyses 5 and 12 were furnished by G. N. Prentiss, chemist Chicago, Milwaukee and St. Paul Railway Company- Analyses 9 and 14 were furnished by Edgar & Carr, chemists. Analysis 10 was furnished by the Dearborn Drug and Chemical Company, Chicago. Analysis 16 was furnished by C. F. Sidener, chemist University of Minnesota.' 198 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. HENNEPIN COUNTY. By C. W. Hall. SURFACE FEATURES. The upland surface of Hennepin County consists chiefly of moraines, which form a series of irregular hills alternating with sharp depressions generally occupied by marshes, sloughs, and lakes. Minnetonka, the largest of the lakes, is more than 10 miles long and has 221 miles of shore line, so that in this respect it is one of the most remarkable lakes in the country. Southeast of Crow River, in the northeastern part of the county, there is a considerable area of relatively flat land in which few lakes occur. Minnesota River, which borders the county on the south, has a broad valley cut into the upland to a depth of 150 or 200 feet. The Mississippi, which forms most of the eastern boundary, has a valley of more youthful aspect. Above Minneapolis it flows through a nar- row and shallow trench, but in the heart of the city it descends the Falls of St. Anthony, and thence to Fort Snelling at the southeastern extremity of the county, where it is joined by the Minnesota, flowing through a deep but narrow gorge which has been excavated in post- glacial times by the recession of the falls. SURFACE DEPOSITS. Alluvium representing the flood-plain deposits of the present streams occupies the bottom of the valleys of Minnesota and Mississippi rivers, and to a less extent the valleys of some of the larger tributaries. It contains abundant water, but owing to the presence of considerable silt does not give up its water as freely as do the more porous gravels of the drift deposits. The outwash and terrace deposits consist of sand grading into gravel at the base, the whole attaining 50 feet or more in greatest thickness. The outwash deposits form a broad belt along the Mis- sissippi from Dayton to the vicinity of Minneapolis; the terrace deposits are found chiefly within the latter city and on the elevated terraces along Minnesota River. The surfaces of both outwash and terrace gravels are generally comparatively flat, but certain undula- tions appear upon them representing channels of old streams by which they were deposited in the Pleistocene epoch. Except near the eroded margins, the supplies of water which they furnish are generally suffi- cient for domestic and farm purposes. The glacial drift occurs over the greater part of the county. The surficial layer is largely of the gravelly type, especially in the north near the Mississippi. Over most of the county the drift is of a grayish- blue color, which is due to its derivation from the Ordovician and HENNEPIN COUNTY. 199 Cretaceous shales farther northwest. In the southeastern part of the county, however, a considerable amount of red material occurs, doubt- less brought from the Lake Superior region far to the northeast. The thickness of the deposits varies, but probably averages 100 to 120 feet, or even more, and in a number of wells in the Lake Minnetonka region reaches a maximum of more than 200 feet. Considerable water exists in the interbedded gravel layers, and this is the source of supply for most of the farm and domestic wells throughout the southern and western portions of the county. At Minneapolis the drift waters have, however, become greatly reduced because of the heavy demands which hundreds of wells make upon them. In the correlation of well records from different parts of the county it has become obvious that along certain lines the drift is much deeper than elsewhere, thus plainly marking the position of preglacial or interglacial stream channels. One of these buried valleys lies within the city of Minneapolis and extends from a point near the Mississippi in the north part of the city westward and southwestward through a chain of lakes toward Minnesota River. Its presence and general course can easily be followed by the well sections reported from this vicinity. Another buried channel is suggested beneath Minnetonka, where the drift is more than 200 feet in depth and the rocks occur at a less depth on either side. ROCK FORMATIONS. The Decorah shale is represented by a total thickness not exceeding 30 feet, and the Platteville limestone by an upper layer of impure lime- stone 10 feet thick, a middle layer of shaly limestone 5 feet thick, and a lower layer of argillaceous limestone 15 feet thick. The Decorah shale is present at only a few localities, the most important of which is on the west side of the Mississippi, about 2 miles west of the Falls of St. Anthony. The Platteville limestone occurs in the elevated land in the northern and northeastern portions of Minneapolis and south of that city to Minnesota River, constituting a flat, thin belt several miles long and of undetermined width. This is the rock over which the water flows at the Falls of St. Anthony. It contains some underground water in the joints, bedding planes, and solution passages, but the amounts are too small to be taken into account as a source of supply. The St. Peter sandstone, where not eroded, ranges from 150 to 175 feet in thickness. According to well drillings it is characterized by a number of shale partings in the lower third of the formation. It outcrops in the bluff of the Mississippi below the Falls of St. Anthony, and occurs beneath the limestone at the falls. West of Minneapolis it forms a subglacial belt extending from the Mississippi to the Minnesota, but the exact position of its boundaries can not be 200 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. indicated, on account of the deep covering of drift. The formation contains large amounts of water, especially in the portions away from the river and beneath the bed of the stream. Near the river the water of the upper part is largely removed owing to drainage into the deep valley. The lower part of the formation, beneath the shale, is every- where water bearing, and, although much depleted by the large number of wells that have been sunk to it, still affords supplies to numerous wells in Minneapolis and the vicinity. The Shakopee dolomite is the lowest of the formations that outcrop in the county. It lies beneath the surface deposits in a north-south belt across the central portion but is everywhere deeply covered with drift and carries but little water. The new Richmond sandstone here consists merely of a series of sandy lenses occurring at somewhat different horizons in the lime- stone. Probably in more than one-half the wells of Hennepin County it was not detected by the driller. Where it exists it will supplement the supplies from the other sandstones, although it does not hold as much water proportionately as the St. Peter or Jordan, owing to the presence of the limy cement which partly fills its pores and to its lenticular distribution. The Oneota dolomite reaches a thickness of 100 feet or more. It underlies Minneapolis and the rest of the eastern part of the county, but is seldom utilized as a source of water supply. The Jordan sandstone is SO to 100 feet thick. In the northern part of the county it lies beneath thick deposits of drift and in the neighborhood of Lake Minnetonka it occurs in the preglacial valleys. Like the other formations, it dips eastward, and numerous wells prove its existence in the eastern two-thirds of the county. It is penetrated by the deep wells in Minneapolis and forms a strong water horizon. The St. Lawrence formation, according to the recent investigations of Prof. F. W. Sardeson, consists of two layers of dolomite, one form- ing the upper part of the formation and the other its bottom, between which is interpolated a series of green and blue shales associated with considerable sandstone. There is some water within the formation, but it is too much loaded with mineral salts to be satisfactory for either drinking or commercial supplies, as was proved by two wells which were drilled into it within the city of Minneapolis. The Dresbach sandstone and underlying shales are found in every well within this county that reaches lower than the St. Lawrence. These formations constitute a strong water zone. The red clastic series occurs in great thickness beneath Hemiepin County, as was proved in drilling the well at Lakewood Cemetery in Minneapolis. This well, which reached a depth of 2,150 feet, passed through at least 1,140 feet of these beds and penetrated the HENNEPIN COUNTY. 201 granitic rock. The red series carries a little water, but its yield is utterly insignificant when compared with the abundant supplies that can always be found in the overlying formations. SOURCES OF WATER. The sources of water utilized in Hennepin County are varied, de- pending on the situation, the purpose for which water is desired, the quantity required, and other factors. Lakes. — In this county, probably more than in any other of south- ern Minnesota, the lakes have been utilized for water supplies. This is due to the large population in the cities of Minneapolis and St. Paul, which draws on the surrounding country for food of every description. Many of the market gardens are located beside the lakes, and the crops are freely watered from the supplies which they afford. Around the larger lakes, particularly Lake Minnetonka, Christmas Lake, and Medi- cine Lake, the villas, lawns, and gardens are all watered from pipes leading from the lakes. Streams. — There is scarcely a stream in the county that is not drawn on heavily for water supplies. Indeed, many of them have practically disappeared within the last generation through the demands for water to use upon the adjacent land, and the lakes which are intimately associated with them in the drainage of the county are consequently becoming notably smaller. Springs. — From the Falls of St. Anthony down the gorge of Missis- sippi River to Fort Snelling and thence up Minnesota River to the west line of the county numerous springs issue from the valley walls. The geologic structure determining their occurrence is very simple. The Paleozoic rocks beneath the glacial drift are the floor on which the waters entering the drift flow until their outlet is reached. In other parts of the county, especially from the falls northeastward along the Mississippi to Dayton, and thence along Crow River to the west line of Greenwood Township, there are many excellent springs, but they are neither so large nor so numerous as those along the Mississippi-Minnesota stretch above mentioned. In the interior of the county are also many springs, due largely to the morainic character of the glacial drift. They are utilized extensively as a source of water supply, but within the cities and villages they are liable to contamination and should not generally be used for drinking purposes. In the southwestern part of Minneapolis is a series of springs that feed several lakes. This series includes the Glenwood- Inglewood springs, which provide a large amount of drinking water for the city and which are situated along a slope that forms one side of the preglacial valley now occupied by Bassetts Creek. The Paleozoic rocks are here covered by a gray bowlder clay, upon which 202 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. lies a red bowlder clay. Between these two beds of clay issue the springs. Analyses of several spring- waters will be found in Plate X. The glacial drift. — The glacial drift is the principal source of water supply for the people of the county. Everywhere wells are sunk into this material, and the water stands so near the surface that it is obtained with the greatest ease. Owing to the contamination of the water, however, this supply is fast falling into disuse in the thickly populated parts of the county. The sandstones. — There are three strong water-bearing sandstones in the county, the St. Peter, the Jordan, ami the Dresbach. The St. Peter is first reached in drilling, and is therefore heavily drawn on. The Jordan is sufficiently coarse and porous to allow the water to percolate through it with great freedom, and hence affords copious supplies. The Dresbach sandstone carries a large supply of water. The approximate depths to these zones can be ascertained by referring to Plate X. HEAD OF THE WATER. In the Minnesota Valley along its entire stretch bordering this county, in the Mississippi Gorge below the Falls of St. Anthony, and in the Mississippi River valley in the northern part of the county, the water from the deeper beds will rise above the surface and flowing wells can be obtained. On the upland surface at Minneapolis and elsewhere, however, the water from all horizons remains a short dis- tance below the surface and must be pumped. QUALITY OF THE WATER. The mineral composition of the water from the various sources mentioned above is graphically shown in Plate X. It will be seen that the analyses here given indicate no notable differences in the composition of the waters from the three chief water zones — the St. Peter, Jordan, and Dresbach sandstones. The water from all three is moderately mineralized, the principal dissolved constituents being the bicarbonate radicle, calcium, ami magnesium, which produce some scale in boilers and render the water hard. Much of this scale can be removed by heating the water before admitting it into the boilers, and the same process will reduce its hardness or soap-consuming property. The water from the St. Lawrence formation, and without doubt that from the Shakopee and Oneota dolomites and the red clastic series, is harder than that from the three principal sand- stones. The water from the glacial drift (including the springs that ■issue from the drift) varies considerably, but, according to the analyses given, has a slightly lower average hardness than the sand- stone waters. The water from the river also contains considerable quantities of calcium and magnesium and of the bicarbonate radicle, but its average hardness is less than that of the underground waters. SifelSiO,) Oxides of iron and aluminum (Fe, Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na + K) Bicarbonate radicle (HCOj) Sulphate radicle (BO, i Chlorine (CI) Total solids AV. AY 28. 9.2 3.1 137. CLAOIAL DRIFT AV AV 19. 1.4 75. 25. 14. 325. 5.3 308. AV. 14. 1.7 64. 28. 5/6 297. 26. 4.2 354. NEW RICHMOND 15. 68. 29. 11. 360. 7.7 316. 20 AY 16. 4.4 80. 30. 9.4 405. 12. 6.2 350. 107. 32. 19. 342. 125. 22. LHtKSIlACH. ETC City datum 700.5 [Glacial drift. ■ Lkenrah shale 'Platteville limestone St. Peter sandstone r Shakopee dolomite New Richmond sandstone Oneola dolomite Jordan sandstone St. Lawrence formation Dresbach sandstone 840 850 848 845 854 m I ! Shale3 and sandstones Red clastic series AV. 13. 3.4 75. 29. 6.5 378. 21. 2.5 328. ANALYSES OF MINNEAPOLIS WATERS ARRANGED AND AVERAGED ACCORDING TO ROCK FORMATIONS. issl', by .1 \ Dodge. 382 b) .i \ i ge . byG.M. David on 1897, bj Edgar & ■ 'in' porati vi 1 spring wator \nalyi i ■ , 1883, byW, v Noye In 1 1 !■■ 1 1 \ui.ii] spline wilier. Analysis Jan. 21, 18S(i, liy *'. V. NidiMier, ii Glenv I pring watm Inalyaii February, 1885, by J. A.Dodge. 12. Si Vnti j I alls mineral i pring water, : deal Modi, ii 15. Well of J. S. Frankforter. in Well of \ Dickenson, Twenty-fourth venue SE, Analysis i 1894, In ' w Drew Is. W.llal II. S. Soldiers' Ilmne. Analysis . I in in. Well <4 E. S w oodwortb Elevator i 'ompany A Marine] Well of General Electric Company. Analyi , imi, in C. W, Drew, dOmaha Elailway Company. Analy- Analysis Dec. 21, 1897, by Edgar A 21. Will of Chicago, SI. Paul, Minimal mils sisjuly 2(1, mill, by il. M. Davidson 22. Wi'll of Baltimore Parkin- < pany Mariner. 23. Well of O. W. Kossubc. Analysis Feb. Ii. lSlKi. liy F.d«ur A Mariner. 2-1. Well of Minneapolis Biewine ('empair.' Anal v>i s Mav 12, lilllll. bv li M Davidson J.. Weill,! Xurlbern Pa. ilie II. el,..., I 1901, by li. .\ rid on 'I. Well el Nell! P.l, ill. PaillMU elli|>.'li\ : Vuah ii d I., i F : eli e. . .'v i. nil I, mil Saull Ste M '.e r ii .: 27 We||",,(.l .,„ • 8l III 2 u. ll u .',,.. Buildin 29. Wollol >.i Ii '' U He ,1 30, Well of Interior Elevator Company, v- I ' □ B I 96, b Edgar & Mariner ;i Well.. i Minneapolis Knitting Work* \i..P. i l<« ''. I'm. in l I' M.-e.la lii.' Well al Weal lintel A,, all i \u nil ,. In .1 \ IgO :; v.eii ... He e ,, i.i, , i inula i v. He i. 'i V..II ii .1.1 .a iiini. in,.. \ i.i.l s i Ii, , ::i, lam,. |,, \ n .u |, ffi ii " I." I i "•". Building '... dj i In 1894, in C, H Drevi 111 '■■'■ "i i ile "i e Anali i I el, ,, |.»i, | M \ n Me ,1 '., «ell 111 |-..aei hell e, \ I , . .1 I e I : . I . . I T> . 1 , i ;, III I l|.,-| Analysis Fob. 20, 1907, Analysis Sept. 2s. Analysis Api 21, 1899, by Kdgar £ I. \ Ii M,,.| liS Well al line , Mil wailkee uinl SI Paul 1,'nil r. a ■. I,.,, 1000 b; • i'e -in "SI Well al Me. I., i I lain I. 1 01 I to i .in HENNEPIN COUNTY. 203 MINNEAPOLIS PUBLIC SUPPLY. The Minneapolis public water supply is taken from Mississippi River. In early days fire protection was needed for the mills erected around the Falls of St. Anthony and for the groups of stores and shops built along the banks of the stream. The river was drawn on to pro- cure water for this purpose and ever since has furnished the public supply. Some years ago the pumping stations at the Falls of St. Anthony were closed by the city water department and a larger pump- ing station was erected 3 miles or more up the river, where there was no danger of sewage contamination from the city. Later the east-side pumping station was erected. The pollution of the river water is the most serious objection to its use as a city supply. The basin of the Mississippi above the pumping stations contains about 20,000 square miles and is the home of 300,000 to 400,000 people, of whom approximately 75,000 live in cities and villages located on the banks of the river. Under these conditions it is practically impossible to prevent the pollution of the stream and its accompanying serious risk to the health of all citizens making use of the water. Moreover, the immense number of logs coming down the river annually, the contamination from sawdust, and the pollution incident to the residence on the river of hundreds of men engaged in the lumbering industries lead to continual risk in the use of the water. The investigations of the Minneapolis water department have led to the recommendation of settling reservoirs and a sand filtration plant, by which the matter in suspension, and especially the organic content of the water, could be removed. The expense of such a sys- tem, which would amount practically to $1,500,000, led the water department to proceed only to the establishment of the settling reser- voirs. A filtration plant would cost approximately $1,000,000. Meanwhile the question has been raised whether the waters stored in the sandstone formations would not furnish a more satisfactory source. In a comparison of the two prospective sources of supply, sev- eral factors must be considered, the most important of which may be enumerated as follows: (1) The quantity available, (2) the sani- tary quality, (3) the mineral quality, (4) the cost of installation, and (5) the cost of operation. The last-named factor, the cost of supplying the water after the plant is installed, resolves itself chiefly, so far as the underground source is concerned, into a question of the head of the water — that is, the height to which the water will be lifted by artesian pressure and the distance it must be lifted artificially in order to bring it to the surface. The head will depend in large measure on the quantity of water available, and hence these two factors must be considered together. 204 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. The general problem of the yield and head of underground water involves three more specific problems — (1) the total quantity of water now stored in the rock formations, (2) the rate at which new supplies of water will be furnished to the rock formations from winch the water is withdrawn by pumping, and (3) the resistance that the rock offers to the transmission of water. The volume of water in the for- mations underlying Minneapolis is without doubt very large, and the potential annual accession from the rainfall is also great. The cru- cial question, however, pertains to the resistance of the rock to the transmission of water. As no precise data are at hand in regard to the porosity and size of grain of the various sandstones, no definite statements can be made as to the rate at which the rocks will con- duct water under a given pressure gradient. Nevertheless, rough calculations have been made in winch maximum and minimum values for the porosity and size of grain have been used, and these calcula- tions indicate, with favorable assumptions, that if the quantity of water required for the Minneapolis public supply were pumped from wells, even though these wells were distributed over a considerable area and should draw from all the principal water zones, the water level in the wells would be materially lowered. As only a moderate lowering of the water level would greatly increase the cost of pumping, it is evident that a system depending on underground supplies should not be installed without first conducting a careful series of experi- ments on the water-yielding capacity of the available formations. The mineral quality of the various waters has already been dis- cussed; the sanitary problems involve so many issues beyond the proper scope of this report that they can not be considered here. HOUSTON COUNTY. By 0. W. Hall and M. L. Fuller. SURFACE FEATURES. The upland surface of Houston County is a much dissected plateau 1,150 to 1,300 feet above sea level and more than 500 feet above the valley of Mississippi River. Where the upland surface remains the topography is relatively level, but in the vicinity of the streams it is extremely rugged. The sink holes due to the caving of the subter- ranean drainage channels are a common feature, and in some places their linear arrangement is very noticeable. A thin covering of loess subdues irregularities and helps to make the upland surface more nearly level. SURFACE DEPOSITS. There is little or no glacial drift in this county, the only covering for the rocks being the residuum resulting from their decay and the HOUSTON COUNTY. 205 mantle of yellow silt or loess, the whole rarely more than 25 feet thick. In the early days many shallow wells were sunk into the loess and residuum, but it was found that the supplies from this source were small and uncertain. In the valleys of Mississippi River and its tributaries there are alluvial deposits which vary in thickness from a few feet to nearly 200 feet, the usual range being between 50 and 100 feet. Water occurs everywhere in these deposits, but because of the clay silt present it is yielded rather slowly in many wells. In the gravel fan at the mouth of Root River, opposite La Crosse, the materials are coarser than elsewhere, and larger supplies should be obtained at this point than elsewhere. In general the yield is smaller than that from the underlying rocks. There are many terraces along the sides of the Mississippi River valley. They extend up the tributary valleys and form an important economic as well as an interesting topographic feature. Owing to the leakage on the exposed valley sides wells must be sunk about to the level of the flood plain before permanent water supplies can be obtained. ROCK FORMATIONS. Rock outcrops occur everywhere along the cliffs of the valleys of the Mississippi and its tributaries, affording abundant opportunity for the determination of the character and thickness of the succes- sive beds. The rock formations outcropping at the surface are all Paleozoic. The green Decorah shale is represented by a thickness of 25 feet, and is underlain by a massive bed of Platteville limestone,, averaging 15 feet in thickness. Because of resistance to erosion, together with geologic position, these formations constitute the highest land in the county, capping the high areas in the southwestern corner. They yield small supplies to shallow wells, but are of little value as a source of water. Some springs occur at the margins of their areas, but most of the water sinks through the crevices of the formations into the underlying sandstone. The St. Peter sandstone here is about 80 feet thick, or only one- half the thickness of the same formation in Hennepin County. It occurs beneath the Platteville limestone in the southwestern part of the county and underlies a large area of the uplands south of Root River. Although cemented by iron and somewhat resistant in places, a condition due to surface alteration, it does not generally give rise to rock exposures, the outcrop area commonly being flat and covered with grass and trees. It yields moderate supplies of water to shallow wells, but owing to the free escape of its water to the adjoining low- lands it does not afford amounts sufficient for industrial or public supplies. 206 UNDERGROUND WATERS OP SOUTHERN MINNESOTA. The Shakopee dolomite is about 75 foot thick, occurring beneath the uplands above t ho river valleys. It carries some water in joints, bedding pianos, and solution passages, and gives rise to a number of springs, but it does not generally afford supplies adequate even for domestic and farm purposes. The New Richmond sandstone, which ranges up to 35 feet in thick- ness, is exposed beneath the Shakopee in the uplands several hundred feet above the stream. It affords little water along its outcrops, but where it is covered by younger rocks, as in the southwestern portion of the county, it may furnish supplies of considerable importance to moderately deep wells, though generally the amounts will prove insuf- ficient for industrial or public supplies. The Oneota dolomite, which is approximately 150 feet thick, out- crops in the upper portion of the cliffs bordering Mississippi and Boot rivers and their tributaries and forms conspicuous bluffs and pinnacles. The upper portion is often broken and characterized by the presence of chert and other concretions. It contains some water in joints, bedding planes, and solution passages. Along the borders of the valley springs of considerable importance issue from this for- mation, a few yielding sufficient quantities for industrial or public sup- plies and even for water power. The Jordan sandstone, a coarse buff sandstone about 100 feet thick, outcrops below the Oneota in the cliffs bordering Mississippi and Root rivers. In the greater part of the county it yields abundantly, the public supplies for several villages being derived from it. Near the outcrops, however, the yield is greatly reduced because of the escape of the water into adjacent valleys. The St. Lawrence formation consists of green and gray calcareous shales with some green sand and occasional sandstone layers, having a total thickness of about 175 feet. It outcrops in the lower portions of the cliffs of the Mississippi and underlies the bottom of Root River and the lower portions of its tributaries to the western border of the county. It contains considerable water in the sandy layers and is said to yield ilows at a few localities in the valleys. It has, how- ever, little value as a water zone, its yield being materially less than that from the overlying Jordan or the underlying Dresbach sandstone. The Dresbach sandstone is a massive, crumbling sandstone about 60 feet thick, with occasional cemented layers. It outcrops along the cliffs of the Mississippi and beneath the alluvium of Root River. Its base is approximately at the level of the Chicago, Milwaukee and St. Paul Railway along the Mississippi. It is a strong water-bearing formation, and in the valley of Root River yields abundantly, the water being used for industrial and public supplies. Beneath the upland it contains large quantities of water, but there is generally no HOUSTON COUNTY. 207 advantage in sinking to it, as the supplies are not materially larger than those from the Jordan except near an outcrop of the latter. Underlying the Dresbach sandstone are several hundred feet of shale and sandstone, which lie almost entirely below the level of the flood plain of the Mississippi and are encountered only in deep wells. The upper portion consists of blue and green shale and the lower of porous sandstone. The shale furnishes an impervious cap, which confines the water in the sandstone, thus giving rise to splendid flows from the sandstone in the valleys of Mississippi and Root rivers. The yield is generally sufficient for all purposes, including industrial and public supplies. Beneath the last-mentioned sandstone are the red shales, sand- stones, and quartzites of the red clastic series, which rests upon the granitic rock. Neither the red clastic series nor the granite will yield much water. Following is the section of an artesian well drilled in 1878 in the village of Brownsville for the Chicago, Milwaukee and St. Paul Railway Company. The granite was here encountered at about 70 feet above sea level. Well section at Brownsville. [Authority, W. E. Swan, driller.] Thick- ness. Depth. Alluvium: Blue clay Basal Cambrian: Limestone Blue shale Green shale Sandstone (probably including some of the Algonkian (?) red clastic series). Granite (entered 20 feet). Feet. 40 60 70 375 Feet. 40 65 125 195 570 UNDERGROUND WATER CONDITIONS. Head of the water. — Flowing wells can be obtained in the valleys of Mississippi and Root rivers throughout their entire extent in this county and also in the lower courses of the tributary streams (PL IV). On the upland the water in the deep wells remains several hundred feet below the surface. For example, in the village well at Caledonia it is reported to stand about 250 feet and in the village well at Spring Grove about 300 feet below the surface. Quality of the water. — The water from all horizons is moderately mineralized, the principal constituents being calcium, magnesium, and the bicarbonate radicle. (See the accompanying table of analyses and PI. V.) A wide variation in the waters of this county in normal chlorine content was noted by H. C. Carel a in his investigations several years ago. A general statement summarized from these reports is to the effect that the deep-lying water-bearing strata are a Eighteenth Rept. Minnesota State Board of Health, 1899-1900, pp. 241-260; Nineteenth Rept., 1901-2, p. 346-356. 208 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. much more heavily loaded with chlorine than the shallower beds. At Houston in 1900 there were 28 artesian wells, ranging in depth between 230 and 310 feet, all obtaining their water from sandstones lower than the Dresbach. The shallowest of these wells yielded the least chlorine, 44.2 parts per million; the deepest yielded 187.2 parts per million. On the higher ground around Houston, where the sup- plies are drawn from the Jordan, the New Richmond, and even from so high a formation as the St. Peter, the amount of chlorine is appre- ciably less. The average chlorine content of springs flowing from these formations is, for the county, only 4.6 parts per million. As a summary of Card's investigations the following figures have been compiled from the large amount of material gathered by him: Average chlorine content of underground waters. Parts per million. Springs (several formations) 4.6 Shallow wells 2. 8 Jordan sandstone 9. 4 Dresbach sandstone 13 Lower sandstone 9.5 Red clastic series 76 Springs. — There are springs along the base of the cliffs at numerous points, the waters draining freely from the rocks wherever they are cut by deep valleys. In the vicinity of Hokah many springs rise from the base of the Jordan sandstone. Several miles west of Hokah is Stimpson Spring, which was long a favorite resort and which is reported to issue from above an impervious limestone as a stream of considerable size. When the county was first settled there were many gristmills operated by water power, and streams issuing from springs were frequently utilized. Winnebago Creek, Pine Creek, Thompson Creek, Money Creek, Beaver Creek, Crooked Creek, and Crystal Creek are all examples. WATER SUPPLY FOR CITIES AND VILLAGES. Caledonia. — The village of Caledonia and the farms adjacent have reported a number of wells ranging from 250 to 312 feet in depth, in some of which the water stands more than 250 feet below the surface. A generalized section of these wells is given below. General section at Caledonia. Thick- ness. Depth. Loam clay and bottom of St. Peter sandstone . Shakopee dolomite New Richmond sandstone Oneota dolomite Jordan sandstone (entered 40 feet). Feet. 70 40 10 150 Feet. 70 110 120 270 a Winchell, N. H., Final Rept. Geol. and Nat. Hist. Survey Minnesota, vol.1, 1882, p. 208. HOUSTON COUNTY. 209 The public supply is obtained from a well 320 feet deep. Two analyses of the water are given in the table (p. 210). About 3 miles from Caledonia there is a spring which for many years was used by the Chicago, Milwaukee and St. Paul Railway Company for locomo- tive supplies. An analysis of water from this spring is also given in the table. Houston. — The village of Houston lies in the valley of Root River, which here apparently flows over a bed of the St. Lawrence formation. In the valley flowing wells are obtained from the Dresbach and lower sandstones. The public waterworks are supplied from a well 6 inches in diameter and 302 feet deep, which has been pumped at the rate of 130 gallons a minute. The water rises 12 feet above the surface, or about 960 feet above sea level. All the people depend on private supplies. Spring Grove. — The village of Spring Grove is situated in the highest portion of the county, where the Platteville limestone occurs. The public waterworks are supplied from a well 396 feet deep, but many of the private wells are shallow. The water in the deep wells stands far below the surface. Hokah. — Along the valley of Root River in the vicinity of Hokah there are flowing wells with considerable head. In several wells where the situation is favorable the natural head of water is used to operate hydraulic rams that lift the water to levels to which it would not otherwise rise. At Hokah this inexpensive and convenient method of pumping is employed at the village waterworks. Ordi- narily this device raises sufficient water, but a gasoline engine can be used in case of shortage. The village well is 544 feet deep, the water rising 18 feet above the surface or 692 feet above sea level. The yield exceeds present needs, though in the past there has been some difficulty owing to the loss of water either through a leak in the casing or through the uncased portion of the sandstone. An analysis of the water is given in the table. The public supply is used by about one-half the people and about 5,000 gallons is consumed daily. SUMMARY AND ANALYSES. The three strongest water-bearing formations are the Jordan, Dresbach, and basal Cambrian sandstones. On the upland they lie at depths of several hundred feet and the water stands far below the surface. In the deepest valleys they occur at or near the surface, and where not exposed by erosion give rise to flows. The basal Cam- brian sandstone is best protected from erosion and is therefore the best artesian zone. The water from all sources is moderately hard. 60920°— wsp 256—11 14 210 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Mineral analyses of water in Houston County. [Analyses in parts per million.] 1. 2. 3. Depth feet.. Silica (Si0 2 ) Iron (Fe) Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+K) . Bicarbonate radicle (HCO3) Sulphate radicle (SO4) Chlorine (CI) Total solids IS 25 110 299 300 320 61 21 9.3 326 5 1.3 267 49 ' 28 6.3 264 3.4 23 246 102 31 30 389 61 47 406 331 4.6 280 3.9 137 15 13 435 24 34 441 69 31 3.3 335 27 4.2 300 1.7 64 24 56 279 50 71 404 5.3 62 28 11 327 18 286 320 16 2.7 70 31 11 256 12 30 322 544 9.2 2.9 76 29 6.7 343 28 4 279 1. Spring at Caledonia used by the Chicago, Milwaukee and St. Paul Railway Company. 1892. 2. Spring at Hokah used by the Chicago, Milwaukee and St. Paul Railway Company. 1892. 3. Chicago, Milwaukee and St. Paul Railway well at Houston. October, 1892. 4. Chicago, Milwaukee and St. Paul Railway well at River Junction. June, 1900. 5. Chicago, Milwaukee and St. Paul Railway well at Spring Grove. July, 1892. 6. Chicago', Milwaukee and St. Paul Railway artesian well at River Junction. April, 1902. 7. Chicago, Milwaukee and St. Paul Railway well at Houston. May, 1895. 8. Village well at Caledonia. July, 1894. 9. Village well at Caledonia. November, 1906. 10. Village well at Hokah. November, 1906. Analyses 1 to 8, inclusive, were furnished by G. N. Prentiss, chemist Chicago, Milwaukee and St. Paul Railway Company. Analyses 9 and 10 were made for the United States Geological Survey by H. S. Spaulding. JACKSON COUNTY. By O. E. Meinzbr. SURFACE FEATURES. In general the surface of Jackson County slopes very gradually from the southwestern corner, which is nearly 1,600 feet above sea level, to the northeastern, where the altitude is about 1,300 feet. The surface constitutes a nearly level and poorly drained upland prairie covered with lakes, ponds, and swamps. This nearly level surface is, however, interrupted by two prominent physical features. One of these is a morainic belt which has a more irregular topography and a higher general altitude than the surrounding prairie and runs with a north-south trend through the middle tier of townships, also occupying the southwestern corner of the county. The other is the valley of Des Moines River, which is a postglacial gorge between 100 and 150 feet deep. This gorge is a rather striking feature in a region otherwise so little affected by erosion, but its extreme youth is apparent from the fact that it has only a few short tributaries and drains only a narrow strip of land on either side. In the geologic future the system of tributaries will become greatly extended and the sluggish streams on the undissected uplands will be captured by Des Moines River. Heron Lake, the largest lake in southwestern Minnesota, is entirely within this county. It seems to lie in the nearly obliterated valley of an ancient stream which once flowed southeastward along the line of Lake Yankton, Lake Shetek, Heron Lake, and Spirit Lake." oUpham, Warren, Pinal Rept. Geol. and Nat. Hist. Survey Minnesota, vol. 1, 1882, p. 507. JACKSON COUNTY. 21L SURFACE DEPOSITS. Description. — The glacial drift forms a mantle which everywhere covers the older formations and averages between 200 and 300 feet in thickness. At several points south of this county the thickness revealed by drilling was somewhat less than 300 feet; in the southern half of the county many wells end in drift at 200 to 300 feet below the surface, and several apparently at still greater depths; in the northeastern and north-central parts underlying formations have been reached at 250 to 300 feet. In some localities in the north- western part, however, the drift is relatively thin, owing to the pres- ence of a buried quartzite ridge. Thus in the vicinity of Okabena the rock has been reached at depths of about 150 feet, in the village of Heron Lake at 110 and 195 feet, and at points just across the Nobles County line at 100 and 120 feet, although the average thick- ness in the northwestern part is greater than these figures would indicate. The following section, to a depth of 350 feet, is typical of the drift. It is the log of a well drilled near Jackson, on the farm of H. W. Miller, NE. \ sec. 30, T. 102 N., R. 34 W. Well section near Jackson. [Authority, Gilbert Nourse, driller, Jackson.] Thick- ness. Depth. Yellow bowlder clay Blue bowlder clay Yellow bowlder clay White sand Blue clay (bowlders at 300 feet) Yellow clay "Light green" clay ("greasy," contains pebbles). Fine sand Feet. 25 175 15 5 130 5 5 Feet. 25 200 215 220 350 355 360 368 Yield of water. — Seams of sand and gravel thick enough and coarse enough to yield adequate supplies are found at some depth in nearly every locality. The 10-inch village well at Lakefield and the 8-inch village well at Alpha serve as examples. The former, which termi- nates in a thick gravel layer 190 feet below the surface, has been pumped for eight hours continuously at the rate of 175 gallons a minute; the latter, 96 feet deep, has been tested for two hours at 100 gallons a minute. The alluvial deposits in the valley of Des Moines River often provide large quantities of water from very shal- low depths. Head of the water. — In a region having a relatively low altitude there is usually not much difference in the head of the water from different depths, that from all horizons coming near the surface. The eastern part of Martin County affords a good example of this condition. 212 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. On the other hand, in an area of relatively high altitude, where the water has many opportunities to percolate to lower levels, there is likely to be an important difference in the head from the various horizons in the same locality, the water frequently coming nearer the surface in the shallow than in the deep wells. Jackson County, and especially the morainic belt occupying the central part, offers a good illustration of this second condition. Thus, at Lakefield there is a gravelly bed at a depth of 80 or 90 feet from which the water rises within about 10 feet of the surface, and another at 180 feet from which it rises only within about 100 feet of the surface; in the deepest wells of this region the water frequently remains still farther below the surface. Near Des Moines River the head is lowered by seepage into the valley, as is shown by the many springs along the valley sides. Quality of the water. — The waters from the glacial drift are repre- sented in the accompanying table (p. 216) by analyses 2 to 7. They all contain considerable quantities of calcium and magnesium, together with large amounts of sulphates, for which reason they have a great permanent hardness and will deposit hard scale in boilers. The water from the alluvium in the Des Moines Valley is only moderately hard and hence is better adapted for use in boilers. It is represented by analysis 1 in the table. CRETACEOUS SYSTEM. Description. — In this county and in all the adjoining counties strata of shale and sandstone believed to be of Cretaceous age have been encountered by the drill immediately beneath the drift. It is there- fore probable that they underlie much of this county, though every- where deeply buried. In some localities in the northwestern part, however, they are absent. Plate IX shows the approximate sections of several wells that enter the Cretaceous rocks. According to S. J. Moe, of Lakefield, a well on the farm of A. L. Bradley, SW. \ sec. 35, T. 103 N., R. 36 W., east of Lakefield, is about 500 feet deep, passing through nearly 200 feet of shale and ending in sand. Yield of water. — In all but the northwestern part of the county formations of sand or sandstone will probably be found at depths ranging from about 250 to 500 feet. These will generally furnish copious supplies of water, but the unconsolidated sand will cause trouble in some wells if not skillfully handled. Head of the water. — On the upland prairies the water from deep sources will remain at depths of 100 to 250 feet. In the valley of Des Moines River it will of course rise nearer the surface, but flows can nowhere be expected. Windom, Minn., and Estherville, Iowa, are both situated in this valley, the former being just north of the Jackson County line and the latter several miles south. In neither JACKSON COUNTY. 213 city can flows be obtained from the Cretaceous. The water seems to rise to about 1,250 feet above sea level in the northern part of the county and to somewhat less than 1,200 feet in the southern, while the valley of Des Moines River is more than 1,300 feet above sea level at the northern boundary and more than 1,250 feet at the southern. Quality of the water. — Analysis 8 in the accompanying table repre- sents Cretaceous water. It is high in calcium, magnesium, and sulphates, and is therefore a hard water and poor for boiler purposes. PALEOZOIC FORMATIONS. At Lake Park, Iowa, a few miles south of this county, a well was drilled for the railway company to a depth of 804 feet. Stratified formations, chiefly shale, sand, and sandstone, seem to make up about 550 feet of this depth. The upper portion is supposed to be Creta- ceous in age, but the lower probably belongs to some Paleozoic for- mation. This well was tested with a large steam pump. The water is said to stand nearly 300 feet below the surface, or about 1,200 feet above sea level. It is so hard that it is not used by the railway company. SIOUX QUARTZITE. In most of this county the Sioux quartzite or "red rock" lies many hundreds of feet below the surface, but in the northwestern part it is sometimes encountered at depths of 100 to 200 feet. The well data which have been assembled show that a completely buried quartzite ridge extends with a northwest-southeast trend through parts of Murray, Nobles, and Jackson counties (PI. III). This ridge is sepa- rated by a deep depression from the quartzite area in Pipestone and Rock counties, and also apparently from that in Cottonwood County. It is smaller than these areas and does not rise so high. In Pipestone County the rock rises to more than 1,700 feet above sea level, and in Cottonwood County to about 1,500 feet; the extreme altitude reached in this area, so far as is known, is about 1,370 feet. In preglacial times it formed a low ridge, and in pre-Cretaceous times it must have stood up conspicuously above the surrounding country. At present it is entirely concealed beneath Cretaceous and glacial deposits. No quartzite wells were reported east of Heron Lake nor south of Okabena station. The Sioux quartzite will invariably yield some water if the drilling is carried deep enough, the water coming from the joints and less firmly cemented portions. The railway well at Heron Lake, whose section is given on Plate IX, is 6 inches in diameter at the bottom and was tested at 90 gallons a minute. The head and quality of the water from the quartzite are similar to that of the overlying formation. 214 UNDERGROUND WATERS OP SOUTHERN MINNESOTA. WATER SUPPLIES FOR CITIES AND VILLAGES. Jackson. — The village of Jackson is situated upon the banks of Des Moines River which has here cut a valley about 100 feet deep. On the west side of the river there is a narrow flood plain and a series of four terraces standing- at levels 15, 40, 60, and 80 feet higher. The valley is carved out of the glacial drift, and the ilood plain ami terraces are covered with deposits of alluvium. The public supply is pumped from a well 26 feet in diameter and 20 feet deep, cased with brick and mortar. It is located at the north end of the village on the Hood plain near the river and terminates in alluvial gravel. In July, 1907, the water stood about 10 feet below the surface and was lowered about 3 feet when the well was pumped for two or three hours at the rate of about 300 gallons a minute. In times of severe drought, however, the yield is so much reduced that the well can be emptied in a short time. An analysis of the water is given in the table. About 600 people are supplied and 50,000 gallons of water is consumed daily. About two-thirds of the inhabitants use water from private wells, which are bored or dug into the alluvial gravels and are very shallow. These gravels are saturated with water and usually yield generous supplies, but the probability of pollution is great, especially on the lower levels. The Chicago, Milwaukee and St. Paul Railway Company uses water from the river. Lakejleld. — The glacial drift is deep at Lakeiield, and the under- lying formations have never been reached in drilling. There are porous water-bearing deposits (1) near the surface, (2) at a depth of 100 feet or less, and (3) at a depth of about 185 feet. The fol- lowing is the approximate section of the upper 190 feet: Well section at Lakefield. Thick- ness. Depth. Yellow bowlder clay Feet. 15 10 10 140 15 Feet. 15 Gravel ." 25 Yellow bowlder clay 35 Blue bowlder elav (.frequently sand at about 100 feet) 175 Sand and grave) 190 Blue bowlder clay. The public supply comes from a drilled well, which has already been described. About 200 people use the water, and the daily con- sumption amounts to approximately 25,000 gallons. The mill well is 180 feet deep and taps the same zone that furnishes the public supply. The water from both is hard but is probably as good for JACKSON COUNTY. 215 boiler purposes as can be obtained. Several analyses are given in the table. About 80 per cent of the-people depend on private wells, most of which end in the yellow clay or gravelly seams near the surface, but some of which penetrate to the beds of sand at depths of 100 feet or less. Heron Lake. — All the people of Heron Lake are supplied from pri- vate wells; there are no public waterworks. Most of the data in regard to the railway well, whose section is shown on Plate XV, have already been given. The fact should be added, however, that the 25-foot bed of sand and gravel at the base of the drift was tested and found to yield about 65 gallons a minute from an 8-inch hole. Alpha. — The village of Alpha lies upon a nearly level drift-covered plain. The public waterworks are supplied from a drilled well that has already been described. An analysis of the water is given in the table. All the people use water from private wells, most of which are shallow and yield moderate and uncertain supplies. There are, however, a few private drilled wells that are deeper and more satisfactory. FARM WATER SUPPLIES. By far the greater number of the farms are supplied by bored wells 1 to 3 feet in diameter and cased with wood or tile. Some end in the surficial yellow clay or gravel, but many pass through blue bowlder clay and tap seams of sand and gravel at depths commonly ranging between 50 and 100 feet. The shallow wells are liable to furnish only small and uncertain supplies, but the deeper ones yield much more copiously. There are also a few drilled wells scattered through the county, most abundant in the northern part. They have a wide range in depth. Some are less than 100 feet deep and terminate in the same beds as the bored wells, but others have been sunk farther; a num- ber of farm wells more than 300 feet deep are reported. Several extend to the Cretaceous strata, and a very few in the northern part penetrate the quartzite. The most desirable type for farm purposes is the 6-inch drilled well finished with an open end. It is more permanent, yields more water, and is better protected from pollution than the bored type. Two-inch wells should not be drilled in this county, for they require screens, which become cemented by minerals precipitated from the water. If a screen must be put into a 6-inch well it should be con- siderably smaller than the diameter of the casing, so that it can be removed readily when it becomes incrusted. Wells of moderate depth are preferable to very deep ones because the water is likely to rise nearer the surface and to be less highly mineralized. 216 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. SUMMARY AND ANALYSES. The sand and gravel beds lying at moderate depths are the most satisfactory source of water. They are generally superior to the very shallow sources (1) in yield of water, (2) in permanence of sup- ply, and (3) in freedom from pollution; and to the deeper drift deposits (1) in the height to which the water will rise, and (2) in its mineral quality. However, where an adequate supply is not obtained at a moderate depth there need be no hesitation in drilling farther. Deep sandstone zones that would yield abundantly no doubt occur in most of the county, but probably nothing would be gained by sinking to them. Two important questions are always asked in regard to the lower formations: (1) Will they give rise to flows? and (2) Will they supply softer water than the shallower beds ? These questions may be answered for this county somewhat as follows: Flowing wells can not be obtained from deep horizons, and on the upland the water will always stand far below the surface. In regard to soft water the answer is less certain. No soft-water beds have thus far been discovered in this county, but there is a possibility that they exist. The probabilities in the case are set forth in the dis- cussion of this subject in the report on Cottonwood County (pp. 157-15SV Mineral analyses of water in Jackson County. [Analyses in parts per million.] Allu- vium. 20 312 25 2.5 Depth feet. . Diameter of well inches. . Silica (SiO.,) Iron (Fe).T Aluminum ( Al) Iron and aluminum oxides (Fe o 3 +AL0..) : Calcium (Caf. I 69 Magnesium (Mg) 29 Sodium and potassium (Na+K).. 54 Carbonate radicle (C0 3 ) j .0 Bicarbonate radicle (HC0 3 ) 381 Sulphate radicle (S0 4 ) I 88 Chlorine (CI) 4 Nitrate radicle (N0 3 ) 3.5 Total solids 4S3 Glacial drift. 96 S 23 2.5 2.3 117 39 62 Ui 142 55 2 671 1S5 6 260 403 3 5 220 81 99 444 697 6 1.326 ISO 31 2.7 72 464* 199 3 692~ 190 10 11 2.8 180 S and 6 6 119 42 33 46l' 145 3 593* 159 45 10 462 217 1.6 662 Creta- ceous. 292 2 14 11 158 57 43 459' 346 3 845~ Sioux quartzite. 9. 10. 217 217 6 8 29 27 10 130 149 276 692 886 33 1,855 82 134 4S9 1. Village well at Jackson. Julv 24, 1907. 2. Village well at Alpha. Julv 24, 1907. 3. Well at Okabena. October IS, 1S95. 4. Well at Prairie Junction. August 30, 1S95. 5. Mill well at Lakefield. Julv 20, 1907. 6. Village well at Lakefield. Julv 20, 1907. 7. Village well at Lakefield. July S. 1902. 8. Well on the farm of Arthur Johnson, 5 miles south of Windom. Julv 19, 1907. 9. Railway well at Heron Lake. September 19, 1900. 10. Railway well at Heron Lake. November 22, 1902. Analyses 1, 2, 5, 6, and S were made for the United States Geological Survey by H. A. Whittaker, chemist Minnesota state board of health. Analyses 3, 4, and 7 were furnished bv G. *N. Prentiss, chemist Chicago, Milwaukee and St. Paul Railway Company. Analyses 9 and 10 were furnished by G. M. David- son, chemist Chicago, St. Paul, Minneapolis and Omaha Raflwav Companv. UNDERGROUND WATERS OF SOUTHERN MINNESOTA. 217 KANDIYOHI COUNTY. By O. E. Meinzer. SURFACE FEATURES. Kandiyohi County has three distinct types of topography and can accordingly be divided into as many physiographic provinces" — (1) the irregular morainic region north and east of Willmar, (2) the area of gently rolling prairie south and west of that city, and (3) the level sandy plain in the northeastern part of the county. All three prov- inces are poorly drained and contain some lakes, but in the first named the lakes are most abundant. SURFACE DEPOSITS. Description. — The surface deposits consist almost entirely of glacial drift, which comprises bowlder clay and beds of sand and gravel. There is no outcrop of older rock and in only a very few places have the underlying formations been disclosed in drilling. Throughout a large portion of the county the drift averages not less than 300 feet in thickness. At Willmar drilling has been carried to a depth of 280 feet; in sec. 6, T. 119 N., R. 34 W., to a depth of 298 feet; in sec. 22, T. 121 N., R. 36 W., to a depth of 303 feet; in sec. 20, T. 121 N., R. 35 W., to a depth of 318 feet; and in sec. 7, T. 120 N., R. 35 W., to a depth of 337 feet, apparently without reaching the bottom of the drift sheet in any case. In the southwest the drift is generally between 200 and 300 feet thick, and in the northeastern part it is also commonly less than 300 feet and is locally thin. The following section shows the material penetrated by the two railway wells at Willmar, all of it probably consisting of glacial drift : Well section at Willmar. [Authority, A. H. Hageland, chief engineer Great Northern Railway Company.] Clay Gravel.. , Clay Gravel Quicksand "Hardpan" Dry sand "Hardpan" Clay and quicksand. Clay Gravel Clay Sand (water) Gravel (water) Thick- ness. Feet. 26 6 42 22 2 65 11 15 10 13 3 14 18 21 Depth. Feet. 26 32 74 96 98 163 174 189 199 212 215 229 247 268 oUpham, Warren, Final Rept. Geol. and Nat. Hist. Survey Minnesota, vol. 2, 1885, pi. 40. 218 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Yield of water. — The beds of sand and gravel are the water-bearing portions of the drift. In the northeast, where these are spread out over the surface, copious supplies can be obtained at slight depths. In the irregular morainic area there are also abundant deposits of water-bearing sand and gravel, but they are intermingled with the bowlder clay in the most complicated manner. In the gently undu- lating province the drift consists more largely of clay; yet in nearly every locality water will be found at some level. As a rule the deepest beds are the most persistent and contribute the largest and most permanent supplies of water, but the structure of the drift is so essentially irregular that every such rule has exceptions. In the vicinity of Willmar three rather distinct water zones are recognized. These are represented in the section of the Willmar railway wells given above by (1) the clay and gravel near the surface, (2) the bed of gravel between the depths of 74 and 96 feet, and (3) the sand and gravel deposit below 229 feet. The railway wells are 10 inches in diameter and are supplied from the lowest of the three zones. One of them was tested with the following results: a (1) Before pumping: Water stood at 10 feet below the surface. (2) After pumping at the rate of 157 gallons per minute for six hours continuously: Water stood 13 feet below the surface. (3) After pumping at the same rate for nineteen hours continuously: Water stood 14£ feet below the surface. (4) After pumping at the same rate for thirty hours continuously: Water stood 14£ feet below the surface. (5) Five minutes after pumping was stopped: Water had again risen to its normal level of 10 feet below the surface. The 8-inch city well at Willmar, which also extends to the deepest of these zones, has been pumped for four hours continuously at the rate of 500 gallons a minute. Head of the water. — On account of the surface irregularities there is considerable difference in the head of the water. In most localities it rises near the surface, and at the base of the high morainal ridge flows can frequently be obtained. There is a group of flowing wells in Lake Andrew Township (T. 121 N., R. 35 W.) and such wells could no doubt be obtained in other localities. At Willmar the water from both the deep zones comes virtually to the surface, or slightly higher than the level of Foot Lake. Quality of the water. — The three analyses given in the accompan} T ing table (p. 221) represent the three types of water found in this county — (1) the water from the sandy deposits at the surface, which is moder- ately hard; (2) the water from the upper portions of the glacial drift (not including No. 1), which is very hard and in which the great quantities of calcium present are largely associated with the sulphate o Furnished by A. H. Hageland, chief engineer Great Northern Railway Company. KANDIYOHI COUNTY. 219 radicle, thus producing much hard scale in boilers; and (3) the water from the lower portion of the drift, which is only moderately hard and contains relatively small amounts of the sulphate radicle. CRETACEOUS SYSTEM. Very little is known of the formations beneath the drift. A thin bed of the Cretaceous, composed chiefly of shale, is without doubt present in some parts of the county, but is not in others. The follow- ing data bear on this subject: (1) Twenty feet of blue shale were pene- trated in drilling 2 miles south of Raymond; (2) shale and sandstone have been discovered in a number of wells in Swift and Chippewa coun- ties to the west; (3) shales have been encountered at Renville, Olivia, and Bird Island, which are 7 or 8 miles south of this county; and (4) Cretaceous rocks, in which fossils belonging to the Benton epoch have been identified, a are exposed about 10 miles beyond the northeastern extremity of this county. No successful wells ending in Cretaceous rocks have been reported. Where these rocks are present they may consist entirely of impervious beds, which would not furnish water, and they are probably nowhere of value as a water-bearing formation. ARCHEAN ROCKS. So far as is known, granite has never been struck in this county, though in a number of places drilling has gone to a depth of more than 300 feet. However, there can be no doubt that it lies generally within a few hundred feet of the surface. The following data throw light on this subject: (1) At Benson, 17 miles west of this county, granite was entered at a depth of about 400 feet; (2) along Minne- sota River, about 14 miles southwest, it is exposed at the surface; (3) at Renville, Olivia, Bird Island, and Hector, 7 to 10 miles south, it has been found at depths of 325 to 450 feet; (4) at Grove City, 4 miles east, it was encountered at a depth of several hundred feet; (5) at a few points not more than 10 miles east it was discovered at depths of less than 300 feet; and (6) in a number of localities 15 to 25 miles north and northeast it comes to the surface. The granite will not supply water, and no water-bearing formation exists below it. WATER SUPPLIES FOR CITIES AND VILLAGES. Willmar. — The stratigraphic section and water zones below Willmar have already been discussed. The upper beds yield very hard water and the lowest provide a softer supply. (See the analyses in the oKloos, J. M., A Cretaceous basin in the Sauk Valley, Minnesota: Am. Jour. Sci., ser. 3, vol. 3, 1872, pp. 17-26. 220 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. table.) The water from all depths rises nearly to the surface. The public supply is taken from a well 8 inches in diameter and 273 feet deep, ending with a screen in the same thick deposit of sand as the railway wells described above. About 1,200 people use this water, and 100,000 gallons is consumed daily. Perhaps 70 per cent of the inhabitants are supplied from private wells, of which most are bored or dug into yellow clay or gravelly seams near the surface and yield small quantities of hard water, but a few are drilled to a depth of about 100 feet and yield more generously. The well at the flouring mill, which is about 100 feet deep, has been abandoned because the water is too hard for boiler purposes. Atwater. — In the village of Atwater sand and gravel deposits near the surface furnish the entire water supply. An unsuccessful well drilled for the municipality passed through beds of sand at about 250 and 400 feet in depth, but although these were water bearing the well was finished in them with difficulty. The public supply is drawn from four wells 3 inches in diameter and about 35 feet deep. They are pro- vided with screens and are pumped by suction at about 75 gallons a minute. The water is only moderately hard, as is shown by the analysis given in the table- below. About 95 per cent of the people use water from private wells, which are bored or driven into the surficial layers of sand, and the railway company is likewise sup- plied from a shallow well. New London. — The domestic supply in the village of New London is obtained chiefly from driven wells. The public waterworks draw from the lake, and surface water is generally used for industrial purposes. FARM WATER SUPPLIES. Three types of wells are in use in this county — (1) driven, (2) bored or dug, and (3) drilled. The driven wells are confined to the localities in which a bed of sand or gravel lies at the surface. In the large area in the northeastern part of the county where this condition prevails, nearly all the wells are driven. They are shallow and inexpensive and usually afford liberal supplies of only moderately hard water. The bored and dug wells are also shallow and do not generally reach the blue clay. Many of them furnish only small quantities of water and fail entirely in dry years, but some yield more abundantly. Most of the farm wells, especially in the morainic area, are bored or dug. Drilled wells, for the most part 2 inches in diameter, are found in nearty all parts of the county, but are most abundant in Arctander Township (T. 121 N., R. 36 W.). They vary greatly in depth, prob- ably averaging not much more than 100 feet. They provide ample supplies in localities where the bored wells fail. As the deep drift layers contain the softest water, there would be an advantage in drilling to them. LAC QUI PARLE COUNTY. 221 SUMMARY AND ANALYSES. In every part of the county the granite probably lies within a few hundred feet of the surface, and deep-water zones therefore do not exist. The glacial drift is, however, several hundred feet thick and contains an abundance of water. In general, the best boiler supplies come from the lower portions of the drift. Mineral analyses of water in Kandiyohi County. [Analyses in parts per million.] Surface deposits. 1. Sur- face sand and gravel. 2. Upper por- tion of glacial drift. 3. Lower por- tion of glacial drift. Diameter of well inches Depth feet Silica (Si0 2 ) Iron ( Fe ) Iron and aluminum oxides (Fe203+ AI2O3) Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+ K) Carbonate radicle (CO3) Bicarbonate radicle (HCO3) Sulphate radicle (SOi) Chlorine (CI) Nitrate radicle (NO3) Total solids 29 2 88 36 7 346 42 35 5 421 34 4 224 76 10 454 227 148 50 1,012 272 8.4 2 3.2 65 35 61 .0 454 56 4 .0 464 1. Village wells in Atwater. September 23, 1907. 2. Well of Nels Anderson at Willmar. September 24, 1907. 3. City well at Willmar. September 24, 1907. The above analyses were made for the United States Geological Survey by H. A. Whittaker, chemist Minnesota state board of health. LAC QUI PARLE COUNTY. By O. E. Meinzer. SURFACE FEATURES. Most of the surface of Lac qui Parle County consists of a plain which slopes very gradually toward the northeast, descending from about 1,200 to 1,000 feet above sea level. This plain is interrupted on the northeast by the valley of Minnesota River, which has here been cut to depths of 100 to 150 feet, and on the southwest by the Coteau des Prairies (Dakota Hills) which lies about 500 feet above the plain. A low morainal ridge crosses the southwestern part of the county with a trend roughly parallel to the margin of the Coteau. The flatness of the plain, which occupies most of this county and extends southward into Yellow Medicine, Lyon, and Redwood counties, stands in decided contrast to the gentle undulations of the Coteau, with its numerous lakes. This difference is explained by Warren Upham as follows : a When the ice sheet, dissolved by a warmer climate, was retreating northeastward across Lac qui Parle County, the waters of its melting were carried to the southeast a Final Rept. Geol. and Nat. Hist. Survey Minnesota, vol. 1, 1882, p. 622. 222 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. along the margin of the ice, which was a barrier preventing their flow in the direction of the present drainage. * * * A glacial lake * * * was formed in the Minne- sota basin along the front of the ice and reached from Faribault and Blue Earth counties to Big Stone Lake. * * * By this submergence the drift in Lac qui Parle County and upon a large part of the Minnesota basin farther southeast was spread more evenly and many of its hollows that would have held small lakes were filled. * * * Dur- ing the somewhat later recession of the ice across Big Stone County, free drainage could take place from its border, and the drift presents a more undulating and rolling surface, dotted by many little lakes. J. E. Todd explains in essentially the same manner the very similar topography of the so-called James River valley in South Dakota on the west side of the Coteau des Prairies. Several streams flow northeastward across Lac qui Parle County. They occupy shallow valleys until as they approach Minnesota River they descend rapidly to its level. They have few tributaries and leave large areas without any well-defined drainage system. SURFACE DEPOSITS. Description. — The glacial drift consists of bowlder clay with asso- ciated deposits of sand and gravel. A thick accumulation of gravel commonly lies at the base, as is shown by the sections given in Plate XL Such a basal gravel is commonly found in other counties, but is especially well developed in this region. Because of the irregular surface upon which the drift rests, its thickness varies greatly within short distances. Throughout most of the county the thickness is between 100 and 200 feet; but in much of the south central part it is less than 100 feet, and 2^ miles south of the county line the under- lying rock comes to the surface; north of Dawson and between Daw- son and Madison the average thickness is more than 200 feet, and the same is true in the southwestern corner of the county (PL II). The Minnesota Valley has been excavated virtually out of the drift, and consequently the underlying rocks are here generally near the surface and in a few localities they form outcrops. Yield, head, and quality of the water. — Supplies adequate for ordi- nary purposes can be obtained in most places from the deposits of sand and gravel in the drift, but where the drift sheet is thin it does not invariably contain a satisfactory water-bearing bed. Throughout most of the county the water rises nearly but not quite to the surface, but within several miles of the Minnesota Valley the « head is lowered by leakage, which manifests itself in numerous springs on the valley side. South of Marietta there are a number of flowing wells which derive their head from the high land to the west. They are not accurately located on the map showing, underground water conditions (PI. II). All the water from the glacial drift is hard. o Todd, J. E., The moraines of southeastern South Dakota: Bull. U. S. Geol. Survey No. 158, 1899, p. 124. . GEOLOGICAL SURVEV Milbank South Dakota Near Bellingham Near Madison South of Dawson Boyd North of Boyd Camp Release Twp. g Yellow clay ^"HardpanlL- ggClay.ek--.^ Blue shale *;-., HardJblue shale iWhite sand Whfecjay IfYellow da; i Gravel I Clay Sand* and gravel " Gravel, 'Vlillll '..lu'll Granite I Blue shale I Hard blue s hale -~ ^ Hard Blue shale Itluc slul.- ''-I'.- " — Dark-colored : ■; , ' : 'White clay" a-fiy- ... Decon-. 1 "-'-™ Hards 'Decomposed si-anile Milbank, s. liuk.- Nal. Ilisl. Survey M Ncarlli-lliiigli-nn. NeaiMadiaon. I 1 11. 10 \V.; lipproxini Norlheast.ofI-.ladi-. preeecling are given i -Given bvN.H. Win nno-ol-., I KS5, p. 14, ( Well "i, farm of I 1 ir.i i-oiecosstul wellon fin , in Fourteenth Ann Kept. Geol. and lli.irilyof.l. \Y. Williams. -.iff, N'W. J see. 12, T. HON., R. 45 W. Jens Jacob-son, SE. \ sec. lj-T.118 N., GEOLOGIC SECTIONS IN LAC QUI PARLE COUNTY. By O.E. Meinzer. South of Madison.— Well on farm of L. P. Satre, NE. } sec. 16, T. 117 N., R. 44 W. Southwest of Dawson.— Well on farm of J. J. Windingstaad, SB. ', see. 14, T. 110 N., R. 44 W. Dawson. — Generalized seel ion soulli of river at Dawson. South of Dawson.— Well on farm of E. A. Throndrud, SW. 1 see. 8, T. 116 N , R.43W. Boyd. — W. Swenson's well. This -eclim, and the six immediately preceding arc given elneflj lie authority ot Nicholas Danielson, driller, Dawson. rr, „.,„,, NE l«ec 33 T 117 N., famp Release Town-hip W ell on lane ol . obi, M ,1 lao.-o„. l\ E. 1 sec. 33, 1. R 41 W Allthorily, J. M. Haul-res, driller, Montevideo Most of the altitudes are only approximately known. LAC QUI PARLE COUNTY. 223 CRETACEOUS SYSTEM. Description. — The Cretaceous rocks include (1) soft, uniform gray- blue shale, or "soapstone," (2) darker and harder shale, and (3) thin beds of unconsolidated white quartz sand. The shale predominates greatly, the only stratum of sand generally being a thin layer at the base of the series, even this being absent in some places. The hardest shale is in most places found next the sand. The Cretaceous rocks are present throughout most of the county, but generally not in the vicinity of Minnesota River, nor that of Lac qui Parle River as far upstream as Dawson, nor in the extreme south central part. Owing to their uneven upper and lower surfaces, the thickness varies, reaching in this county at least 225 feet. The sec- tions given in Plate XI represent the series in its typical development. Yield of water. — In drilling in this county any one of the following three conditions may be encountered: (1) The Cretaceous may be absent, the drill passing directly from the glacial drift into the granitic rocks; (2) shale or "soapstone" may alone be present, in which case the rocks will contribute no water; (3) the Cretaceous may be present and include a layer of sand, which, even if it is thin, may afford liberal supplies. Because the Cretaceous is so irregular in distribution and thickness it is impossible to predict the exact localities in which it will be found as a water-bearing deposit. All except two or three of the sections shown in Plate XI represent successful wells, most of them capable of yielding copiously. The following table gives the data in regard to these wells: Typical wells in the Cretaceous, Lac qui Parle County. a Owner and location. Depth to Thickness water- of water- Yield. bearing bearing stratum. stratum. Feet. Feet. 207 8 Ample . . 237 (?) ...do.... 200 Thin. ...do.... 325 2 ...do 150 (?) ...do 148 li 100 gal- lons (?) 185 (?) Ample. . 185 (?) ...do 135 £ Moderate 142 Thin. Ample.. Head. Hiram Graff, NW. i sec. 12, T. 119 N., R. 45 W Well 4 miles northeast of Madison Lars Roise, SE. i sec. 16, T. 118 N., R. 44 W.6 L. P. Satre, NE.Jsec. 16, T. 117 N., R. 44 W J. J. Windingstaad, SE. \ sec. 14, T. 116 N., R. 44 W Dawson village well c E. A. Throndrud, SW. J sec. 8, T. 116 N., R. 43 W.. OleHusby, NE. } sec. 36, T. 117 N., R. 42 W N . Swenson, in village of Boyd A. Olerud, SW. | sec. 10, T. 116 N., R. 42 W Feet below surface. 40 40 17 60 19 16 70 25 16 22 a The water from all these wells is soft. & Section not shown in PI. XI. c The analysis of this water is given on page 224. Head of the water. — The head is virtually the same as that of wells in the deeper drift zones, the water in most places rising nearly but not quite to the surface. The range in the wells given in the 224 UNDEBGBOTJND WATEBS 01 SOUTHERN MINNESOTA. above bable is 16 to 70 feet below the surface. At Madison the Cre- taceous water rises to about 1,080 feel above sea level, at Dawson to 1,050 feet, and at Boyd to 1,040 feet. Quality of tin water. — The water from the Cretaceous strata is soft but contains large quantities of sodium, the sulphate radicle, and chlorine. The following analysis is typical, except that in some locali- ties there is a much higher content of chlorine. At Madison, for example, the water is perceptibly saline. Mineral analysis of Cretaceous water. Parts per million. Silica (SiOa) 11. 4 Iron and aluminum oxides (AbOj-r-FeoO;^ 3. 6 Calcium (Ca) 10 Magnesium (Mg) 7. 5 Sodium and potassium (Na-{-K) 24S Carbonate radicle (C0 3 ) Bicarbonate radicle (HCO s ) 4S3 Sulphate radicle (S0 4 ) 136 t 'hlorine (CD 27 Nitrate radicle (NO s ) AKCHEAX ROCKS. Granite outcrops at a number of points in the valley of Minnesota River and in a small area 2^- miles south of the county line. It has also been discovered in drilling in nearly every part of the county. As its surface is not regular, it is found at different levels, but in most localities it lies at a depth of several hundred feet. It is nearest the present surface in the region bordering the Minnesota and in the eastern and south central sections of the county. At Dawson it has been encountered at a depth of 155 feet; near Marietta, at 345 feet; and at Milbank, S. Dak., at 283 feet. Where the granite was protected from glacial erosion by overlying formations the upper part is decayed ami is locally veneered by a white clay, which is often wrongly called "marl," but in fact is the leached decomposition product of the granite, though in some places it has been transported and redeposited by water. The granite is not water bearing, except that rarely an adequate supply is derived from gritty parts of the white clay or other decom- posed rock. In the well of John Hanson, the section of which is given in Plate XI, drilling was carried to a depth of 298 feet and entered solid granite without finding water. A charge of dynamite was then exploded, after which the well yielded generously. However, in most wells this procedure would not be successful. « East village well at Dawson. Sample collected August 29, 1907. Analyst, H. A. Whittaker, chemist Minnesota State Board of Health. LAG QUI PARLE COUNTY. 225 WATER SUPPLIES FOR CITIES AND VILLAGES. Madison. — Madison has no public supply. The water zones may be classified as follows: 1. Surficial yellow clay and sand, utilized chiefly by bored wells 30 to 40 feet deep. At present this zone furnishes most of the supply. The water is hard. 2. Seams of sand and gravel in the glacial drift, tapped by drilled wells commonly between 100 and 160 feet deep. This water is also hard. 3. Strata of Cretaceous sand, reached by drilled wells at a depth of about 300 feet, but not yet used much. The water is soft but saline. Dav:son. — The underground water conditions are not the same in different parts of the village of Dawson. On the south side of the river the Cretaceous intervenes between the basal granite and the glacial drift, which is here less than 100 feet deep. At the bottom of the Cretaceous is a thin layer of white quartz sand, which affords soft water (PI. XI). On the north side of the river the drift appears to be fully 200 feet deep and to rest directly on the granite, the soft- water zone being absent. The waterworks, which were completed in 1908, are supplied by two wells south of the river, both of which are about 148 feet deep, and end in the soft-water stratum. The village authorities have reported that the two wells have been pumped at the rate of about 160 gallons a minute for twelve hours continuously. The water is soft but con- tains rather large quantities of alkali sulphates and chlorides, as is shown by the analysis given above. It will be employed large ly for all purposes, its softness recommending it for domestic use. Several other soft-water wells have been drilled on the south side, one of which supplies the creamery. Most of the private wells are bored and end in yellow clay or gravel at depths of 30 or 40 feet, yielding small quantities of hard water. There are a few drilled wells which tap the deeper layers of sand and gravel in the drift and also furnish hard water. The well at the mill is an example of this type. Boyd. — In the well of N. Swenson, the section of which is given in Plate XI, the Cretaceous shale is encountered at a depth of 80 feet, and the white clay, which presages granite, at 130 feet. At other points the glacial drift is known to be deeper. The Swenson well ends in a 6-inch layer of Cretaceous sand and provides a small quantity of soft water, while the well of A. Olerud, which is just north of the village and no doubt reaches the same horizon, affords a larger amount of the same kind of water. It has not been deter- mined how extensively soft water could be obtained. 60920°— wsp 256—11 15 226 UNDERGEOUND WATEES OF SOUTHEEN MINNESOTA. The glacial drift here contains an uncommon proportion of sand and gravel (PI. XI). The 8-inch well which supplies the public water- works is 62 feet deep and draws from this source. The water rises within about 5 feet of the surface, and according to J. M. Haubris, the driller, of Montevideo, pumping at the rate of 80 gallons a minute for fifteen hours continuously lowered this level only 4 inches. The water is hard and is at present used almost exclusively for fire pro- tection. The mill is supplied by a well 120 feet deep, which yields an abundant supply of hard water. Most of the private wells are dug or bored into yellow clay or gravel and many are not more than 20 or 30 feet deep. Bellingham. — The domestic supplies at Bellingham are derived chiefly from private wells 20 to 100 feet deep. The public water- works are also provided with a well, the water being used to a moderate extent for various purposes. The soft-water well of Mr. Hiram Graff, the description of which is given above, points to the possibility that soft water can be obtained in Bellingham. FARM WATER SUPPLIES. There are two principal types of farm wells — bored and drilled. The former are relatively shallow and many of them have not adequate or permanent supplies; the latter are deeper and generally more satisfactory and reliable. By far the greater number stop in glacial drift and yield hard water, but those which tap Cretaceous strata and afford soft water are widely distributed. Many farms now have hard water where a soft-water supply could be procured by drilling a little deeper. Two-inch wells terminating in the drift must be provided with screens, which are liable to become clogged in a few years. Wells of larger diameter are therefore more satisfactory and economical for farm' purposes. SUMMARY. As granite that is not water-bearing lies everywhere within a few hundred feet of the surface, deep drilling should never be undertaken in this county. After the white clay (which generally lies above the granite) has been entered the chances of finding water are very poor, and whenever hard granite is reached drilling should be discontinued. The two sources of underground water consist of (1) sand and gravel deposits interbedded with the bowlder clay and (2) layers of sand below shale ("soapstone"). The former nearly always yields plenty of water; the latter is more uncertain but frequently furnishes ade- quate supplies. The former contains hard water, the latter generally soft. LESUEUR COUNTY. 227 In this region drilling for soft water is to be encouraged, for although there is no certainty that it will be found, the conditions in most parts of the county are favorable to success. Moreover, the experiment is not expensive. If soft water exists at all, it will be reached only a short distance below the hard-water horizons; and the "soapstone," through which it is necessary to pass, is very readily penetrated. If no soft water is found, the casing can usually be withdrawn. On the other hand, drilling for flowing wells in this county is to be discouraged. Although the water usually rises near the surface, no flows can be obtained except in a few small areas where they are derived from shallow layers. Hence all attempts to obtain flows by deep drilling must be considered a waste of money. LE SUEUR COUNTY. By C. W. Hall and M. L. Fuller. SURFACE FEATURES. The upland surface of Lesueur County ranges in height from about 900 feet above sea level near Minnesota River to nearly 1,100 feet in the central and eastern portions of the county. The general level of the plateau is broken by two irregular morainal ridges. One of these, standing 50 to 75 feet above the adjoining plain, extends along the eastern end of the county, lying for 1 to 5 miles of its width in Lesueur County and for the remainder in Rice County to the east. The other ridge, which is of similar character, is only 3 or 4 miles wide and extends from the southeast corner of the county diagonally across the southern townships to Minnesota River near St. Peter. Both the ridges and the general plateau surface, which is undulating or gently rolling, are dotted with lakes, some of which are several miles long. The stream valleys are those of the Minnesota and its tributaries and that of Cannon River in the southeastern corner. The Minnesota River valley lies 100 to 200 feet below the adjacent uplands, but the valleys of the remaining streams, except the lower portions of those entering the Minnesota, are not deep nor character- ized by steep sides. Along the east side of the Minnesota, within its flood plain, there is a strip of low alluvial deposits from one-eighth to one-half mile in width. Above this at Kasota and Ottawa are ter- races 1 or 2 miles wide and underlain by the Shakopee dolomite, described below. Near Kasota and Lesueur there are two of the so-called prairies, representing flat terrace surfaces standing 100 feet or more above Minnesota River. The Lesueur prairie is more than 4 miles wide. Back of these terraces the land rises in a sort of bluff to the upland level, which is generally 50 to 100 feet higher. Along upper Cannon River there are gravel terraces formed by the streams during the glacial period. 228 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. SURFACE DEPOSITS. Lesueur County is everywhere deeply drift covered except along the Minnesota Valley, and even here the rock projects through the alluvium. The surface deposits include alluvium, terrace sands, and unmodified glacial drift. The glacial drift consists of pebbly clay with bowlders and inter- mingled sandy or gravelly layers, the sand and gravel being especially abundant in the moraines. Between the morainal districts stratified outwash deposits have been laid down. The drift attains its greatest development on the uplands near Minnesota River, where it is locally more than 200 feet thick. Water is found in considerable amounts in the various sandy and gravelly layers and is available to wells of moderate depth, enough usually being obtained to supply large industries as well as households and farms. The alluvium consists of loamy sands and gravels deposited in the principal valleys, at some places to a depth of perhaps 100 feet or more. It usually affords supplies sufficient for domestic and farm purposes. The terrace sands and gravels are similar to those of the alluvium except that less silt is present. In the Minnesota Valley they lie about 100 feet above the present stream, having been deposited by the river flowing at the level indicated and left in their present situa- tion on terraces by the subsequent erosion of the stream. Their thickness is generally 20 to 30 feet; beneath them the wells penetrate the unmodified drift. Water is readily absorbed by the porous materials and is commonly abundant in the portions remote from the streams, affording supplies for domestic, farm, and small industrial purposes. Near the valleys the water escapes by percolation to the lower land and many wells fail to obtain the necessary supplies until the underlying rocks are reached. PALEOZOIC FORMATIONS. The Galena and Platteville limestones have not been seen at the surface but have been encountered in wells and probably underlie several square miles of the highland on the eastern border of the county. The St. Peter sandstone, like the overlying Galena and Platteville limestones, has not been seen at the surface but has been found in wells at a number of points, as at Elysian and Waterville. It is 100 feet thick and more and underlies the Platteville and the drift in the southeastern portion of the county. The volume of water which it yields is generally considerable, being sufficient for farm and industrial purposes and for the public supplies of small cities. The water does not occur under great pressure. The Prairie du Chien group is represented by the pink to buff Shakopee and Oneota dolomites, which outcrop at Kasota and other LESUEUR COUNTY. 229 points along the Minnesota Kiver and underlie the drift throughout the western half of the county. Their water supply is limited to the creviced portions and the interbedded lenses of sandstone. On the valley border, where the water escapes readily, the supply lies at a considerable depth. In such localities wells must go below drainage levels to procure adequate amounts of water. On the uplands the supplies are larger and are obtained at a higher level. The best supply probably comes from a sandy bed in the upper part of the group, supposed to be the representative of the New Richmond sandstone of the counties along the Mississippi. The Jordan sandstone, which is about 90 feet thick, outcrops along the Minnesota and dips eastward beneath the uplands underlying the entire county. It can be reached anywhere in the region by mod- erately deep wells and will usually afford supplies adequate for all purposes, the water being under sufficient pressure to cause it to enter the wells freely. Beneath the Jordan sandstone there are about 150 feet of shale and limestone, not water bearing, known as the St. Lawrence formation. Beneath these lies the Dresbach sandstone, a water-bearing bed 50 to 100 feet thick and similar to the Jordan. Its yield, however, is usually no greater than that of the Jordan and there is therefore no advantage in drilling to it, unless the supplies of the Jordan should be locally exhausted by heavy withdrawals. Below the Dresbach there are several hundred feet of shales and water-bearing sandstone beds, below which lie, in turn, the red clastic series and the granite, neither of which is important as a water bearer. UNDERGROUND WATER CONDITIONS. Wells. — The wells of Lesueur County fall into five clearly defined groups: The first includes the shallow wells of the drift-covered uplands, the second the deep upland wells obtaining their supplies from the drift, the third the upland wells entering the rock, the fourth the shallow valley wells ending in alluvium, and the fifth the deep artesian wells of the valleys. The first group, comprising the shallow wells of the upland, are commonly of the dug or bored types. Water is obtained from sandy or gravelly layers of the drift, but the supplies reached are usually small and are liable to fail in dry seasons. The water, too, is not of the best quality. For these reasons the deeper drilled wells are to be preferred. The wells of the second group obtain their supplies from the water-bearing beds yielding good supplies, which are generally found before the rock is struck. The deeper upland wells comprising the third group enter the rock, obtaining their supplies from the St. Peter sandstone, the creviced and sandy portions of the Prairie du Chien group, or the Jordan sandstone. Ample supplies are generally obtained. In the valleys the shallow wells which make up 230 UNDERGROUND WATERS OV SOUTHERN MINNESOTA. the fourth group arc commonly of the driven type and are sunk from 20 to 40 feet into the alluvium. They are especially abundant along the Minnesota. The supplies are usually rather small and of unsatis- factory quality. For large supplies in the valleys recourse is had to deep-drilled wells (the fifth group) which penetrate to the Dresbach and underlying sandstones. From these water is obtained in large volumes and under sufficient head to lift it 75 feet above the river in places. Head of the (rater. — In view of the differences in surface altitude found in this county, the head relative to the surface must vary within comparatively wide limits. Ordinarily the shallow drift wells on the uplands find the ground-water level but a few feet below the surface, whereas the deeper drift supplies and the water from the rock formations stand at a lower level, the head usually becoming progressively lower as greater depths are reached. But in the Minnesota Valley, which is several hundred feet below the uplands, the water from the rock formations will rise above the surface without rising any higher above sea level than elsewhere in the county. In the city well at Lesueur, which is 668 feet deep, the water rises 18 feet above the surface, or 77$ feet above sea level. In the well at Lesueur Center, 340 feet deep (extending 52 feet below the surface at Lesueur), the water rises within 180 feet of the surface, or 898 feet above sea level. In other words, the water at Lesueur Center is lifted 00 feet above the level to which it will rise in the flowing well at Lesueur. Springs. — Springs are very numerous where the Minnesota and its tributaries have cut their valleys into the drift. The water of the drift escapes from the sandy layers at many points and affords sup- plies to numerous farms. The largest springs occur where the lime- stone rises above the valley level and outcrops in the bluffs. This rock serves to collect and concentrate the water from the overlying drift and thus affords a plane along which the water makes its way from the underground supplies to the surface. WATER SUPPLIES FOR CITIES AND VILLAGES. Lesueur. — The 8-inch flowing well which furnishes the public supply for Lesueur is the deepest well in the county. It penetrates far into the Dresbach sandstone and underlying shales, as is shown by the following section: Well section at Lesuew. Thick- ness. Depth. Ft,t. Alluvium and drift 176 St. Lawrence formation (shale and dolomite - ) 100 Dresbach sandstone and underlying shale 392 Feet. 176 276 66S LESUEUR COUNTY. 231 When this well is pumped at the rate of 400 gallons a minute the water is lowered 15 feet below the surface. About one-half the people use the public supply, and approximately 40,000 gallons is consumed daily. An analysis of the water is given in the table on page 232. Waterville. — Waterville has a system of public waterworks supplied from an 8-inch well 185 feet deep, which probably ends in glacial drift. About 10,000 gallons is consumed daily. Montgomery. — The glacial drift in the locality of Montgomery is about 175 feet thick and rests on strata of limestone and sandstone, which are penetrated by a few of the deepest wells. The following is the section of the well drilled in 1904 for the Minneapolis and St. Louis Railroad Company: Well section at Montgomery. [Authority, chief engineer Minneapolis and St. Louis Railroad Company.] Thick- ness. Ucpth. Clay and "hardpan" (glacial drift). Limestone (probably Oneota) Loose sandstone (probably Jordan). Hard sandstone (probably Jordan). . Feet. 175 27 18 32 Feet. 175 202 220 252 The public supply is derived from a 10-inch well which is 213 feet deep. At least one-half of the people use the water, and about 25,000 gallons is consumed daily. Several analyses of water from this village are given in the table. Lesueur Center. — The well that supplies the public waterworks of Lesueur Center is 340 feet deep*. Only a small amount of water is used, as most of the people depend on private wells. Elysian. — The village of Elysian has a well 287 feet deep, which apparently taps the St. Peter sandstone. Only a small proportion of the people use the public supply. Kilkenny. — The waterworks at Kilkenny are supplied from a well 250 feet deep, which derives its water from the St. Peter sandstone. SUMMARY AND ANALYSES. Underlying this region are several sandstones, all of which yield water generously. In the valley of the Minnesota they give rise to flowing wells, but on the uplands no flows can be obtained from rock formations at any depth, for the head of water is lowest in the deep wells. However, the water from the sandstones is not so highly charged with iron as that from the drift and in this respect is dis- tinctly preferable. 232 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Mineral analyses of water in Lesueur Count v. [Analyses in parts per million.] Depth feet.. Silica (SiO«) Caleium*(Ca) Magnesium (Mg) Sodium and potassium (Na+K) B icarbonate radicle (HCCM.. Sulphate radicle (SOO-. Chlorine (CI) Total solids Glacial drift. 19 50 23 135 44S 61 3.7 618 25 80 30 7.6 340 52 1.3 3ft? 1S5(?) 25 54 31 9.6 321 11 3.4 294 Fragile!*] rock formations. 195 4.S 70 14 61 287 73 14 487 344 10 110 36 42 468 64 2.7 578 340(?) 518 67 512 273 51 S 15 9.1 624 273 59 510 85 ti.O 531 273 168 " 1.2 453 4S 1.6 442 315 ■!•) 437 18 1.7 369 140 6.6 114 40 90 545 9S 70 687 668 7.8 55 21 42 270 4S 29 3(16 November, 1901. December, 1901. 1892. 1. Follert's spring in sec. 14, T. Ill N., R. 26 W, 1902. 2. Chicago, St. Paul, Minneapolis and Omaha Railway well at Lesueur. 1901. 3. City well at Waterville. September, 1S97. 4. Montgomery Brewing Company well at Montgomery. May, 1905. 5. Well at the'New Prague Flouring Mill at New Prague. November, 1906. 6. City well at Montgomery. December, 1901. 7. Minneapolis and St. Louis Railroad well at Montgomery. 8. Minneapolis and St. Louis Railroad well at Montgomery. 9. Minneapolis and St. Louis Railroad well at Montgomery. 10. H. H. Flower's creamery well at Cleveland. 1901. 11. Chicago and Northwestern Railway well at Kasota. 12. City well at Lesueur. 1901. Analysis 1 was made by J. P. Magnusson; analysis 3 by C. W. Drew; analysis 4 by the School of Brew- ers; and analysis 5 by EL S. Spaulding. Analyses 2, 11, and 12 were furnished by G. M. Davidson, chem- ist Chicago and Northwestern Railway Company; analyses 6 and 10 by G. N. Prentiss, chemist Chicago, Milwaukee and St. Paul Railway Company; and analyses 7, S, and 9" by the Minneapolis and St. Louis Railroad Company. LINCOLN COUNTY. By O. E. Meinzer. SURFACE FEATURES. Lincoln is a prairie county, most of which lies on the coteau more than 1,700 feet above sea level. In the northeast, however, the surface slopes down to the lowland plain bordering the Minnesota Valley, and in this slope descends about 500 feet within a few miles (Pis. I and V). The coteau abounds in lakes and swamps and has a very imperfect drainage, but the slope has become incised by numerous ravines, some of which are deep enough to be fed by permanent springs. These ravines will gradually be cut down and their heads will slowly encroach on the upland prairie, until in the distant future all of Lincoln County will be dissected into hills and valleys, and the lakes and swamps will have disappeared. The county is crossed by two morainal ridges that rim parallel to each other with a northwest-southeast trend (PI. II). Both can be traced northwestward into South Dakota and southeastward through Minnesota into Iowa. They stand higher than the surrounding prairie and have a more irregular relief. The crest of the outer (or more southwesterly) ridge rises nearly 2,000 feet above sea level. It is interrupted by several remarkable gaps evidently formed by streams in the last glacial epoch. a aTJpham, Warren, Final Rept. Geol. and Nat. Hist. Survey Minnesota, vol. 1, 1SS2, p. 603. LINCOLN COUNTY. 233 SURFACE DEPOSITS. DESCRIPTION. On the coteau the glacial drift is Very thick, but it thins out in the direction of the lowland plain, and in the extreme northeastern corner the North Branch of Yellow Medicine River has cut through it and exposed a sandstone formation. As has just been stated, the coteau forms a relatively even plateau about 500 feet above the lowland plain, the slope from one level to the other being well denned and relatively abrupt. The large fea- tures of the topography (the coteau, slope, and lowland plain) are the same as they were at the close of the Pleistocene epoch, only minor characters be.ng due to more recent erosion. The question at once arises: To what extent is the coteau of preglacial origin, and in how far has it been formed by deposits of drift ? It has been the general opinion that in this region the older forma- tions lie at a higher level than farther northeast and that the greater thickness of the drift accounts for only a small part of the 500 feet of increase in altitude. This was the view of the Minnesota Survey geologists, Warren Upham's statement on this point being as follows: Till, or the unstratified bowlder clay, deposited by the ice of the glacial period, forms a thick sheet, probably averaging a hundred feet in depth upon the surface of all this district (Lyon, Lincoln, and Yellow Medicine counties). * * * Though no exposures of strata older than the drift have been found upon the Coteau des Prairies in this district and northwestward, the underlying formations are believed to rise here much higher than on either side, in the basins of the Minnesota, Big Sioux, and James rivers. The altitude of the coteau is doubtless thus caused by the greater height of the formations, probably Cretaceous, upon which these drift deposits lie, rather than by extraordinary thickness of the drift beyond that which it com- monly has throughout southwestern Minnesota. The depth that is added to the general drift sheet by the accumulations of the terminal moraines does not appear to average more than 50 to 75 feet. Upon the Coteau des Prairies the knolls and hillocks of the morainic belts rise 20 to 50 and rarely 75 or 100 feet above the adjoin- ing hollows; and the thickness which they add to the drift sheet appears to be from 50 to 150 feet. At the time this statement was made there were no deep wells in the region, the deepest one reported in Lincoln County being 94 feet. Hence there was no direct evidence as to the thickness of the drift. Knowledge is still very imperfect, but a number of rather deep drillings made in recent years indicate that Mr. Upham's statement will require some modification. It still seems altogether probable that the elevation of the coteau is to large extent caused by older formations (though as yet there is no proof of this in Minnesota); but the well data at hand show that the average thickness of the drift is here much greater than on the adjacent lowland plain, and a Final Rept. Geol. and Nat. Hist. Survey Minnesota, vol. 1, 1882, p. 601. 234 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. that so far as this county is concerned a considerable part of the higher elevation results from this greater thickness. The well records also seem to indicate that the present margin of the coteau is determined by the deposits of drift, and that locally the underlying formations are no higher above sea level beneath the coteau than beneath the lowland plain. The following table, showing the altitude of the top of the Creta- ceous (or the bottom of the drift "i on the plain near the foot of the coteau. is introduced here for comparison with similar data to be given for Lincoln County. Altitude above sea level of the surface upon which the glacial dr(ft rests, for specified points, at the foot of the coteau. Feet. Tracy 1. 235 Amiret 1. 200 Marshall 1. 125 Ghent - 1. 200 Minneota 1. 155 Canby 1. 140 All the drillers at Marshall assert positively that they have never encountered anything on the coteau or the upper part of the slope but sand, gravel, and ordinary pebbly clay, though on the lower part of the slope and on the lowland plain they constantly drill into "soap- stone," which is the name they apply to the Cretaceous shale. They all differentiate between "soapstone" and the blue clay of the drift which contains pebbles and bowlders. Near Russell (Lyon County), on the farm of T. Thompson. XE. \ sec. 30. T. 110 X., R. 42 TV., the following well section is reported: Well section near Russell {Lyon County^. Thick- ness. Depth. Feet. Fa>. Gravel, sand, and blue elav 2S0 ?>0 Blueelay 80 360 Sandv blue elav 15 ' 375 Sand! ". 15 390 This weU was sunk by Adair Brothers, of Marshall, who drill chiefly in the Cretaceous on the lowland plain, but who report that nothing in the nature of "soapstone'' was reached at this place. If the entire section consists of glacial drift , the surface of the underlying formations is here less than 1.200 feet above sea level. At Tyler the following section is reported for the old village well, the thickness of the various beds being only approximately correct. LINCOLN COUNTY. 235 Well section at Tyler. ■ Thick- ness. Depth. i Feet. 1 40 Feet. 40 70 110 20 130 100 230 100 330 170 500 1 5 505 45 550 1 8 558 Yellow clay Blue clay Quicksand Blue clay Yellow clay and gravel. Blue clay Hard layer Blue clay Gravel..' This well was drilled by Oxholm Brothers, of Arco, who also sunk the well at the former "ounty poor farm (4 miles north and 1 mile east of Lake Benton) to a depth of 560 feet and several other wells in the county to depths of about 500 feet. These men have drilled in shale in South Dakota and hence distinguish between that material and the blue clay of the glacial drift. They state emphatically that they have never encountered shale in Lincoln County. They also report bowl- ders, generally more or less decayed, between depths of 300 and 500 feet. If the above section consists entirely of drift, the surface of the underlying formations is here not more than 1,190 feet above sea level. The railway well at Tyler reached a depth of 575 feet. In reporting this well the representative of the railway company states that " all material penetrated is characteristic glacial deposit. " If this is true, the older formations at this point do not rise more than 1,175 feet above the sea. The following section is given for the unsuccessful well at Ivanhoe : Well section at Ivanhoe. Thick- ness. Depth. Yellow clay Red sand Blue clay Yellow clay Sand Shale Blue clay (contains pebbles and bowlders). Conglomerate Soil ("perfectly black") Yellow clay Blue clay (entered) 53 23 29 150 93 10 77 1 3 11 37 Feet. 53 76 105 255 348 358 435 436 439 450 487 If the beds here passed through are all drift, as they appear to be, the underlying surface is not more than 1,260 feet above sea level. The testimony of all the drillers in Lincoln County is to the effect that the glacial drift is very deep and that the Cretaceous shale or "soapstone" is never penetrated. Three other deep wells have been 236 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. drilled in the county — at Ivanhoe, Tyler, and Lake Benton — but no reliable section could be obtained. In the western part of Murray County the drift is also reported to be very thick, but no drillings were saved from the deep wells. At Wilmont, in Nobles County, a coarse gravel containing pebbles that show glacial striae occurs at a depth of 348 feet. It is notable that the valley of Minnesota River, the margin of the coteau, and the three morainal ridges (two in this county and one farther northeast) are all parallel. It seems probable (1) that before the Pleistocene epoch the territory now occupied by the coteau was in general a relatively high area; (2) that this preexisting highland modi- fied the course of the ice tongue of the last and probably those of earlier glacial invasions; (3) that this ice tongue acted much like a valley glacier, scouring its channel and forming thick deposits at its margin; and (4) that the thickest accumulation of drift occurs near the edge of the coteau and in preexisting valleys of the region. On the west side of the Coteau des Prairies (in South Dakota) where the upland descends to the so-called James River valley, the topo- graphic features of coteau, slope, and "valley" are strikingly similar to those on the eastern, and the history of the two sides is probably similar. On both sides ice tongues are believed to have acted in much the same way and to have been followed by temporary lakes which smoothed out the lowland surface. On both sides also post- glacial erosion has been most active on the slope. YIELD OF WATER. The sand and gravel deposits of the glacial drift are usually water bearing. The 6-inch village well at Tyler, which is 230 feet deep, has been tested at 35 gallons a minute, and the 6-inch railway well at the same place, which is 575 feet deep, at 88 gallons a minute. Generally, however, supplies adequate for ordinary purposes can be procured at more moderate depths. HEAD OF THE WATER. Flowing wells are found in the valley of North Branch of Yellow Medicine River in the northeastern corner of the county. It is pos- sible that an occasional flow may also be obtained in other localities near the foot of the moraines, but there is no important artesian basin. As a rule, the water stands near the surface in shallow wells and far below the surface in the deepest wells. However, in the deep railway well at Lake Benton, which is situated in a gap in the outer moraine, the water rose nearly to the surface. QTTALITY OF THE WATER. The water from the glacial drift is all hard. Most of it is extremely hard and highly mineralized and is very poor for boiler purposes. The analyses in the accompanying table seem to show that the least LINCOLN COUNTY. 237 mineralized water is that from very shallow wells, and this is prob- ably true, though the samples represented are too localized to war- rant any general conclusion. The water from the deep well drilled at Lake Benton for the railway company (analysis 10 in the table, on p. 239) is also less mineralized than the average drift water, but nothing is known as to the source of this sample except the depth of the well. • UNDERLYING FORMATIONS. Description. — Sandstone supposed to belong to the Cretaceous system is exposed in the valley of North Branch of Yellow Medicine River, a and other outcrops occur in Lyon County. This is probably the same sandstone that lies above the principal shale or "soap- stone" beds at Canby, Minneota, and Marshall. The Cretaceous of Lyon County, known to attain a thickness of nearly 500 feet, is believed to extend below the drift of Lincoln County and to be con- tinuous with the thicker formations farther west. (See the discus- sion of the Cretaceous in the report on Lyon County.) About 7 miles west of Minneota there lies beneath the drift a 40-foot bed of limestone which, if report is to be trusted, probably lies stratigraphic- ally above the outcropping sandstone. In the vicinity of Elkton, 1 mile west of the state line, the Sioux quartzite has been encountered at depths of 200 feet and less, and in one well in the southeastern part of this county (sec. 30, T. 109 N., R. 44 W.) hard rock that may belong to the same formation was struck at a depth of 450 .feet. In the north the Archean granite occurs immediately below the Cretaceous. Yield, head, and quality of water. — As very little is known from direct evidence in regard to the Cretaceous of this region, the reader is referred to the report on Lyon County. Throughout most of Lincoln County the water from the sandstones would remain at depths of several hundred feet. In the northeastern corner the altitude is low enough so that it would rise nearly or quite to the surface, but the principal water-bearing bed, elsewhere in the county, is not present here, the granite being found in its stead. In general, the Cretaceous water is even harder than that from the drift, but certain soft-water zones have been discovered in Lyon and other counties. WATER SUPPLIES FOR CITIES AND VILLAGES. Lake Benton. — The outer moraine crosses the region about Lake Benton, and the village lies in a unique gap in the moraine, caused by a stream that once flowed southwest ward. The glacial drift is known to be very thick. The well which furnishes the public supply aUpham, Warren, Final Rept. Geo. 1 , and Nat. Hist. Survey Minnesota, vol. 1, 1S82, pp. 598 and 599. 238 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. is L2 feet in diameter ami was sunk to a depth of 10 foot, chiefly through sand ami gravel. It is cased with brick ami admits water at all levels. In the summer of 1907 the lake had risen almost to the top of the well, which was nearly full of water. The well has been tested at 400 gallons a minute ami is reported to yield an ample supply even in dry years. The water is hard, as is shown by the analysis given in the table below. It is used by about 250 people, the average daily consumption amounting approximately to 7,500 gallons. Most of the private wells are of the dug or bored variety ami are shallow, but there are also a few drilled wells, most of which are less than 100 feet deep. Tiller. — The glacial drift is very thick near Tyler, as is shown by the sect ion on page 235. The public supply is derived from a well 6 and S inches in diameter and 230 feet deep, which has a brass screen at the bottom. The water rises within 70 feet of the surface, or 1,680 feet above sea level. When the well was completed, in 1906, it was pumped for about twenty hours continuously at the rate of 35 gallons a minute. The water is very hard and contains much iron, which is oxidized and precipitated when exposed to the air. It is utilized for various purposes, but seems to be avoided for drink- ing and cooking because of its iron content. Shallow private wells are in general use. The mill and creamery are supplied from drilled wells that yield very hard .water. An analysis of the water from the creamery well is given in the table. IvanTboe. — The public waterworks in the village of Ivanhoe are supplied from a 10-inch well that is finished with a screen at a depth of 315 feet, the water being reported to rise within about 100 feet o( the surface. Most of the private wells are sunk into yellow clay and are shallow, but there are a few deeper drilled wells. The strati- graphic section, to a depth of 4S7 feet, has boon given on page 235. Hendricks. — The well that furnishes the public supply for Hen- dricks is 10 feet in diameter ami 10 feet deep and ends in sand and gravel below a layer of clay. Perhaps 75 people use the water, ami on an average 3,000 gallons is consumed daily. Most of the inhabit- ants rely on shallow private wells. I'AKM WATER SUPPLIES. There are two principal types of farm wells — bored and drilled. The former are shallow and terminate in yellow clay or are some- what deeper and reach sand and gravel beds beneath a layer of blue clay. Their depth averages less than 50 feet and is rarely as much as 100 feet. Wells of the latter type range from less than 100 feet to nearly 500 feet in depth, the great majority being between 100 and 200 feet. The most satisfactory type for farm purposes is the 0-inch drilled well. LINCOLN COUNTY. 239 SUMMARY AND ANALYSES. Throughout most of the county strata of sandstone, which would afford large quantities of water, are believed to exist, but they lie at considerable depths and the water would generally stand several hundred feet below the surface and be extremely hard. Soft-water zones containing adequate supplies may occur, but they are easily passed through unnoticed in drilling. If any further prospecting for soft water is undertaken, the careful methods described in the chapter on problems relating to wells (pp. 95-96) must be followed or failure will be almost certain. The sandstone may give place to granite in the northern and to quartzite in the extreme southern part of the county. In the northeastern corner, where the altitude is low, such sandstone strata as do exist will be encountered rela- tively near the surface, and the water will rise almost or quite to the surface. The Sioux quartzite should not be penetrated unless no other source of supply is available. The granite should never be entered, because it is not water bearing. Mineral analyses of water in Lincoln County. [Analysis in parts per million.] Depth feet Diameter of well inches Silica (Si0 2 ) Iron and aluminum oxides (Fe203 4 AlaOa) Calcium (Ca) Magnesium ( Mg; Sodium and potassium (Na+Kj... Bicarbonate radicle ( HCO3) Sulphate radicle ( S0 4 ; Chlorine (CI) Total solids Surface sand and gravel. 10 21 45 4.8 99 27 54 216 284 3 623 16 144 1 26 140 45 30 403 286 2 735 20 2 28 2.06 186 55 31 534 279 20 8&3 207 63 34 403 469 20 1,016 Glacial drift. 24 24 72 I 1 , 29 21 1.6 180 58 32 573 255 16 855 24 130 30 6 422 99 9 527 140 2 26 407 97 238 956 1,091 7 2,337 575 10,8,6 42 5 318 127 309 941 1,147 15 2,427 585 2 31 3.5 311 103 198 724 976 15 1,994 (?) 10. 27 1.7 121 47 25 410 198 6 628 1. Well on the shore of Lake Hendricks, at Hendricks. June 22, 1900. 2. Village well at Lake Benton. December 8, 1893. 3. A test well at Lake Benton. June, 1891. 4. A driven well at Lake Benton. November 29, 1898. 5. Well at Lake Benton. July 20, 1891. 6. A driven well at Lake Benton. June 10, 1902. 7. Creamery well at Tyler. January 31, 1900. 8. Railway well at Tyler. January 22, 1901. 9. Railway well at Tyler. December, 1899. 10. Railway well at Lake Benton. June 30, 1X92. The above analyses were furnished by G. M. Davidson, chemist Chicago and Northwestern Railway Company. 240 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. LYON COUNTY. By O. E. Meinzer. SURFACE FEATURES. The topographic features of Lyon County are unique. As the map shows (PL I), the surface descends from about 1,750 feet above sea level in the southwestern corner to about 1,075 feet in the north- eastern corner. But the grade is not uniform. As far as the 1,500- foot contour the descent is slight, thence for some miles it is relatively rapid, and below the 1,200-foot contour it is very gradual. The county is thus divided into three physiographic provinces — the upland plain, the slope, and the lowland plain. The upland plain occupies the southwestern corner and forms a part of the Coteau des Prairies, which extends westward into South Dakota. It is crossed by a moraine, and in some parts is hilly, though generally only gently undulating. It is poorly drained and contains many lakes and swamps. The only stream of any consequence is Redwood River, which rises in Pipestone County and flows north- eastward across Lyon County. The slope from the upland to the lowland is not precipitous. It is not a cliff or escarpment, but only a gradual descent. Nevertheless, the gradient is sufficient for the surface waters to erode actively, and consequently this tract has become dissected by numerous ravines and valleys, all of which run northeastward toward the lowland plain. The largest have been cut deep enough to tap the upper zones of underground water and are now fed by springs. Extensive stream capture is destined to take place in this region before the drainage, which is still extremely youthful, shall have become adjusted. The lowland plain of this county is a part of a much larger expanse lying between the coteau and Minnesota River. It is very flat and quite featureless. It is crossed by Yellow Medicine, Redwood, and Cottonwood rivers, which descend from the coteau and here occupy shallow valleys with but few tributaries, thus leaving the general surface of the plain poorly drained. SURFACE DEPOSITS. Description. — The glacial drift, which is a mixture of clay, sand, and gravel, ranges in thickness from a thin veneer to perhaps more than 400 feet. It is most attenuated in that portion of the lowland plain that lies next the slope from the coteau. Here the average depth is less than 50 feet, and in a few places streams have cut down to the underlying formations. Toward the northeast it thickens grad- ually, in some localities on the lowland plain attaining a depth of 100 feet ; toward the southwest it thickens greatly and rapidly, within a few miles reaching a depth of several hundred feet. LYON COUNTY. 241 At Taunton, Minneota, Ghent, Marshall, Heckman, and Dudley the average thickness is less than 50 feet ; in the country surrounding Green Valley it is between 50 and 100 feet; in the locality of Cotton- wood, about 100 feet; at Amiret, about 80 feet; and in the vicinity of Tracy, between 100 and 200 feet. Three miles northeast of Lynd (SW. i sec. 19, T. Ill N., E. 41 W.) underlying shale was found at 155 feet; but wells in this village reach 125 feet, and a well near Russell 390 feet, apparently without passing out of the drift, the average thickness of which on the coteau is probably more than 300 feet. (PI. II.) Yield of water. — On the lowland plain in the northeastern part of the county the drift is too thin to be a reliable source of water, and in some localities it contains no water-bearing bed; but on the upland plain in the southwest it is deep and includes thick seams of sand and gravel, which afford abundant and permanent supplies. Head of the water. — There are a few small areas of flowing wells supplied from the drift. Many of these wells are just outside of the Cretaceous flowing area and are located in the valleys on the slope (PL IV). Generally, however, these valleys have been cut so deep that they have tapped the water-bearing seams and allow the water to escape through springs, thus destroying artesian conditions. Flowing wells from the drift have been reported as follows: (1) A group of very shallow wells about 5 miles southwest of Minneota, on sees. 16, 17, 20, and 21 in T. 112 N., R. 43 W.; (2) a well 66 feet deep on the farm of H. Kuhling, NE. £ sec. 6, T. Ill N., R. 42 W.; (3) a well 89 feet deep on the farm of Sobinskie Brothers, SW. J sec. 36, T. 110 N., R. 41 W.; and (4) a well 85 feet deep 3 miles north of Tracy, on the farm of O. Pierce, NE. { sec. 2, T. 109 N., R. 40 W. No doubt there are other small areas in which flows could be obtained. Quality of the water. — The water is very hard and very poorly adapted for use in boilers. In some wells, especially on the lowland plain, it is too rich in magnesium, alkali, and sulphates to be satisfac- tory for drinking and culinary purposes. CRETACEOUS SYSTEM. DESCRIPTION. The series of shales and sandstones shown in Plate XII has been penetrated in an indefinite number of wells in all parts of Lyon County except the southwestern, where the drift is very deep. Although there is no direct fossil evidence as to the age of these rocks, there can be no reasonable doubt that they constitute the eastward exten- sion of the Upper Cretaceous of South Dakota. Their geographic position and lithologic character and the head and mineral composi- tion of the water all indicate this. 60920°— wsp 256—11 16 242 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. As far as is known the upper surface of the Cretaceous has no great irregularities. A line drawn from the southeastern to the north- western corner of the county would represent approximately its 1,200-foot contour. Thus at Tracy its altitude is about 1,235 feet; atAmiret, 1,200 feet; at Marshall, 1,125 feet; and at Minneota, 1,155 feet. From the 1,200-foot contour it descends gradually toward the northeast, reaching about 1,000 feet in the northeastern corner. Less is known about the Cretaceous surface in the southwestern part, but it certainly does not rise as much as the present surface of the land. In the sections given in Plate XII the Cretaceous ranges from 125 to 455 feet in thickness, but the extreme range is somewhat greater. In the northern and especially the northeastern part its thickness is least, the granite coming near the surface; in the central and south- ern parts it is commonly penetrated to depths of 350 to 450 feet, and the bottom is rarely reached. It probably thickens westward be- neath the coteau. There is so much monotony in the sections of the Cretaceous that it is not possible to correlate them with certainty from well records. The stratigraphic succession at Marshall has been determined most accurately, and many well sections within 5 or 10 miles of that city, especially to the east and southeast, have been correlated with it. The main artesian zone (B in PL XII) and the principal soft-water zone (D in PL XII) are well recognized there. YIELD OF WATER. In the vicinity of Marshall the following water-bearing strata are found: (1) The shallow zone. The section for the first 100 feet below the surface is not constant, but there are several sandy layers which yield abundantly. (2) The soft-water zone. This occurs at a depth of 250 feet and supplies a number of wells, but its yield is so small that were it not for the relative softness of the water, it would not be utilized at all. The soft-water well at the new mill will fur- nish about 2 gallons a minute with the pump at the bottom of the well. (3) The 300-foot zone. In Marshall a hard impervious layer is encountered at about 300 feet below the surface, or 50 feet below the soft-water zone ; but 1 mile east of the city, on the farm of C. H. Middleton (SE. \ sec. 3, T. Ill N., P. 41 W.), there was found asso- ciated with this hard layer a 6-foot sandstone stratum which gives rise to a flow of 2 or 3 gallons a minute, and near by, on the farm of C. E. Overstrud (NE. \ sec. 3, T. Ill N., R. 41 W.), the same hard layer and artesian sandstone stratum were penetrated. These wells show that a layer at one place water bearing may at no great distance be quite impervious, and that small amounts of water are commonly associated with the hard layers so frequently encountered in drilling LYON COUNTY. 243 through the soft shale. (4) The main artesian zone. About 400 feet below the surface occurs the sandstone that supplies most of the flowing wells of the vicinity. In Marshall it furnishes sufficient amounts of water for all ordinary purposes, but at some distance east, southeast, and northeast its yield is very small. (5) The deep zone. The new mill well extends to a depth of 490 feet and is evidently sup- plied from a lower source than the other artesian wells in the city. It is reported to flow 600 gallons a minute from a 6-inch pipe. At Minneota the Cretaceous contains the following water-bearing beds: (1) Several layers of sand and sandstone between the depths of 25 and 110 feet. These are probably to be correlated with the shallow zone at Marshall. They yield abundantly. The 6-inch village well, which is supplied from this source, has been pumped con- tinuously for twenty hours at the rate of 30 gallons a minute. (2) A stratum of sand at a depth of 250 feet. This would probably fur- nish considerable water, though the sand is fine and incoherent. In the region between Minneota and Ghent the same two zones occur that are given above for Minneota. Near Cottonwood and farther west water is found at a depth of about 100 feet and at 150 feet or more. In the entire northern part of the county the main artesian sandstone is absent and the granite exists in its place. East of Marshall, in the vicinity of Dudley, there are two princi- pal sources from which the wells draw their water — one at depths ranging from about 160 to 230 feet, and the other at an average depth of about 400 feet. The former corresponds, in a general way, to the soft-water beds at Marshall, and the latter to the main artesian sandstone of that locality. The supply from the former varies, but is usually small; the latter yields copiously in the district west and south of Dudley, but fails entirely farther east and north where the granite is nearer the surface. The shallow deposits of sand found at Marshall do not seem to be represented here. Partial list of ivells that end in the upper water zone in the vicinity of Dudley, showing owner, location, and depth. Feet. J. G. Schultz, SW. I sec. 1, T. Ill N., R. 41 W 230 T. L. Wolf, NE. \ sec. 12, T. Ill N., R. 41 W 220 E. De Clerk, NE. \ sec. 6, T. Ill N., R. 40 W 212 Margaret Lenerds, \ sec. 6, T. Ill N., R. 40 W 190 Chris. Rock, NW. \ sec. 5, T. Ill N., R. 40 W 170 C. Schoel, NW. \ sec. 4, T. Ill N., R. 40 W 160 B. Snyder, SW. \ sec. 4, T. Ill N., R. 40 W 178 W. E. Heagle, NW. \ sec. 9, T. Ill N., R. 40 W 190 F. W. Ludwig, SW. \ sec. 3, T. Ill N., R. 40 W 166 H. Snyder, NW. \ sec. 14, T. Ill N., R. 40 W 190 Benj. Christianson, NE. \ sec. 14, T. Ill N., R. 40 W 162 R. Castle, SW. \ sec. 14, T. Ill N., R. 40 W 190 244 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Partial list of wells that end in the lower water zone in the vicinity of Dudley, showing owner, location, and depth. Feet. W. H. Baughman, SE. \ sec. 12, T. Ill N., R. 41 W 405 Watt Fuller, SW. \ sec. 13, T. Ill N., R. 41 W 403 C. W. Snyder, NW. \ sec. 29, T. Ill N., R. 40 W 435 J. Ciesielski, NW. \ sec. 28, T. Ill N., R. 40 W 425 E. C. Kochrane, SE. \ sec. 15, T. Ill N., R. 40 W 356 J. F.Fischer, NE. J sec. 22, T. Ill N., R. 40 W.a 345 Near Amiret and in the region east and northeast of that village there are numerous wells ranging from less than 400 to more than 500 feet in depth, and a large proportion of these yield generously. The strata in which they end apparently correspond, in a general wa}-, to the lower artesian sandstones at Marshall, the granite being here deeply buried. At Tracy the best water-bearing bed exists 600 feet below the surface. The 6-inch city well, which extends to this depth, has been pumped for fifteen hours continuously at the rate of 50 gallons a minute. From the data that have been given, the following provisional correlation of the water-bearing members of the Cretaceous can be made: (1) Shallow zones — represented by the sandy beds generally less than 100 feet below the surface in the vicinities of Marshall, Ghent, Minneota, Cottonwood, etc. (2) Intermediate zones — represented by the 250-foot and 300-foot strata in the locality of Marshall, the 250-foot sand layer in the region about Ghent and Minneota, and the upper sources in the vicinity of Dudley. (3) Deep zones — represented by the lower sandstones in the terri- tory including Marshall, Dudley, Amiret, and Tracy. HEAD OF THE WATER. The area in which the Cretaceous gives rise to flowing wells lies on the lower portion of the slope from the coteau and on adjacent parts of the lowland plain. It is 6 to 8 miles wide and extends from the vicinity of Ghent southeastward into Redwood County (PI. IV). With few exceptions, only the deep zones produce flows. The southwestern margin of the area crosses Lynd and Sodus town- ships (T. Ill N., R. 42 W., and T. 110 N., R. 41 W.) in a direction nearly due southeast, and then turns more nearly eastward and crosses the southern part of Amiret Township (T. 110 N., R. 40 W.). It lies between the 1,200-foot and 1,300-foot contours. Northwest of Amiret it nearly coincides with the latter, but as it is followed south- eastward it gradually descends, leaving the county at an altitude of about 1,250 feet above sea level, and getting down almost to 1,200 feet at Walnut Grove, 6 miles east of the county line. In the F. Mellenthine well, 1 mile south and 6 miles west of Marshall (SW. \ o The section of this well is given in PI. XII. GEOLOGIC SECTIONS IN LYON AND WESTERN By O. E. Meinzer. Vicinity of Cottonwood. — Generalized for the vicinity of Cottonwood. The section is .nllli ulist different lit (I i ffereill localities. Canhy (Yellow Medicine Comity). — Deep well drilled lor the villaee; record pre- served by villain' authorities. . Mioneola.— The upper 111) feet is seuer.ili7.ed. 'I he section below that depth i- fchat oi the Bowing well belonging to H. A. Rush, as reported by W. A. Crowe, the original NearGhent — Well Smiles norl T. 112 N.. It. 42 W. The altrti from Adair Brothers, drillers. Ma Marahall.— Generalized from i Wheeler, O. W. Martin, and Will hash i penetrated only in thee The section of the old weel of Ghent, on farm of J. DeCock.NW ! sec. 7, le is only approximately known. Data obtained ball. dividual sections given by Adair Brothers, S. P m MoColgan, drillers at Marshall. The last 75 feet wuiill well, and no accurate data could he obtained. as reported by J. E. Todd in Water-Supply Pape Theseelinn of Iheold null veil was r.-;.cr: -1 I .'.I. la. . a..c- ... . - ■-; 1 i - -I" i 3 Qeo] Survey No. 102, 1903, p. 481. P, Upper shale and sandstone; E, pnn- YELLOW MEDICINE COUNTIES. cipal shale series (upper portion); D, intermediate sandstone, etc.; C, principal shale serin (lower portion); It. main artesian sandstone; A, ba-al series M ear Dudley —Well ;! miles -out heast of Dudley, on (arm .it .1.1'. I'laohor, it. , see. 22, T. Ill N., R. 40 W.; approximate. The altitude also is approximate. AUllmri'lics, Adair Ibotbors, drillers, Marshall. Aniiret — Flowing well at Aiuiret owned bv Webb & McLaughlin; approximate. Authorilv, O. \V, Marlin, driller, Marshall. , Tru-y ' -Deep v. II drill,. I al Ti „-, in 111" wilder,,! Iss., SI,. II van re| od b; Prof. N. H. Winchell (Four nth Ami lb ' ' ">'" "'.' *.'" "^ ',!",',','," sera, ISSa, p|>, :. ,i ii i ■. '.',,.., a ■, . , Dan ei ■, e.n.n in., ''aue. The well was diill.d by Swan e; SI u ev, and the drl lings were oxaiuin. .1 h> 1 ro o-.jr Winohell. The description of the sti Lynd Township.— Well drilled in on the farm of F. Mellenthine. SW. i Met a, lean, driller, Marshall. " mil' and Ii miles west of Marshall. ,9, T. Ml N., R 42 W. Authority, William LYON COUNTY. 245 sec. 9, T. Ill N., R. 42 W.) the water rises slightly above the surface at an altitude of about 1,290 feet; in the well at Amiret it overflows at 1,280 feet; at Tracy it rises to about 1,230 feet; and at Walnut Grove to 1,216 feet. The northeastern margin is approximately parallel with the south- western. Starting north of Ghent it passes over Grandview and Fair- view townships (T. 112 N., R. 42 W., and T. 112 N., R. 41 W.) to the southeast corner of the latter township. Thence it crosses Clifton Township (T. Ill N., R. 40 W.) diagonally, and leaves the county near the southeast corner of this township. The southwestern margin of the flowing area is evidently de- termined by the surface altitude, but another explanation is necessary to account for its limits toward the northeast, for the surface con- tinues to descend in this direction. The failure to obtain flows on the lower ground to the northeast may result from either of two causes, decrease in the artesian pressure or interruption of the artesian zone. It was observed that near the margin the wells commonly give rise only to very small flows, and that in some wells at least this is not due to lack of pressure but rather to the absence of any bed that will yield much water. The well on the farm of T. L. Wolf, NE. | sec. 12, T. 11 1 N., R. 41 W., will serve as an example. It is located near the northeastern margin, is 520 feet deep, and has a section similar to that of the successful flowing wells immediately to the west and south. At the depth of 410 feet it penetrated a hard and nearly impervious layer which corresponds stratigraphically to the much thicker and more porous sandstone that gives rise to flowing wells farther west and south. This nearly impervious layer yielded only a slight flow, which, however, had a good pressure. Farther northeast no flows are obtained because deep drilling fails to find water-bearing beds. The flowing well at Minneota, whose section is given in Plate XII, is another illustration of this condition. It yields only a few gallons a day, the water escaping drop by drop; yet when the top of the well is closed the confined water exerts considerable pressure, showing that the small yield is not due to a lack of head. Moreover, the water can be pumped down to any level almost instantly. The main artesian zone is evidently absent, and only a minute quantity of water is transmitted by the nearly impervious white formation. In some wells the pressure is slight or the water does not rise to the surface, but a general survey of the conditions has led to the conclusion that the flowing area does not extend farther east and north primarily because of the rise of the granite surface and the consequent interruption of the principal artesian sandstone. At Marshall the pressure has diminished to a marked extent since the first flowing wells were sunk. The following data are for the main artesian zone. 246 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Decrease in artesian pressure in wells at Marshall. Depth of well. Date of test. Head above Head above surface. sea level. Old flouring-mill well a M. Guiseke's well c. . . . Feet. 392 11894. t (») (1901. \1906. Feet. 207 161 131 70 Feet. 1,375 1,329 1,300 1,240 a Authority, chief engineer Marshall flouring mill. b In U. S. Geol. Survey Water-Supply Paper No. 102, 1903, p. 4cSl, J. E. Todd states that the head is reported to be 161 feet, but gives no date, c Authority, Adair Brothers, drillers, Marshall. The data given for the city well, which is 410 feet deep, substantially corroborate those given in the above table. In 1895 it had a pressure of 90 pounds to the square inch; that is, the water would have risen 207 feet above the surface, or fully 1,375 feet above sea level, but at present the head is much lower — probably lower than that given for the Guiseke well in 1906. a There are no flowing wells at Tracy, but the head there also has been greatly lowered. In the city well, which is about 600 feet deep, the water is reported to have risen in 1892 to a level about 50 feet below the surface, or 1,360 feet above the sea, whereas in 1907 it was reported to remain 180 feet below the surface, or 1,230 feet above sea level. Tins shows approximately the same loss of head as at Marshall, and suggests that the decrease of pressure may be a general phenomenon. In the well at the new flouring mill in Marshall, which reaches a deeper source than the other flowing wells of the city, the pressure at present is 40 pounds to the square inch; that is, the water would rise about 92 feet above the surface, or 1,270 feet above sea level. The 250-foot zone at Marshall yields so little water and has been pumped so hard that the head has been lowered greatly. It once produced flows, and even as late as in 1906 the water in the mill well is reported to have risen, when the well was not pumped for a week, within 16 feet of the surface. A few flowing wells end in the 300-foot stratum. QUALITY OF THE WATER. The analyses given in the accompanying table (pp. 251-252) show that in some important respects the Cretaceous waters of this region are similar and in other respects they differ widely. They are all highly mineralized, but they vary greatly in the total amount of mineral matter that they contain. Likewise they are all characterized by a large content of sodium and of sulphates and chlorine, but there is a great difference in the absolute quantities of all these. They differ most radically, however, in their content of calcium and mag- nesium, and hence in their hardness and scale-forming properties. a Information furnished by Eugene Simmons, superintendent of the public waterworks, Marshall. LYON COUNTY. 247 The quality of the water from the various Cretaceous strata will be discussed under the heads of shallow zones, intermediate zones, and deep zones. Shallow zones. — The water from the shallow sources at Marshall is very hard, as well as rich in the alkali sulphates, and that from the strata near the surface at Minneota is similar. Intermediate zones. — The water that comes from depths interme- diate between the shallow and deep zones seems to be relatively soft. The following data bear on this point: The water from the 250-foot and 300-foot strata at Marshall is soft, as shown by analyses 6, 7, and 8 in the table. In the J. DeCock well, near Ghent (PI. XII), the 9-foot stratum that lies at a depth of 265 feet supplies water which is considered soft. At Minneota the 10-foot layer of sand encountered at a depth of 246 feet in drilling the deep flowing well (PI. XII) is reported to contain soft water. In the vicinity of Cottonwood the water from the lower beds — that is, from depths about 150 feet — is said generally to be soft (for exam- ple, the old mill well, which was 152 feet deep) . In the village well, the water, which is supposed to come from a depth of 175 feet, contains great quantities of common salt (sodium chloride), but is rather soft and not otherwise excessively mineralized. In the region about Dudley the wells between 160 and 230 feet in depth, given in the list on page 243, all yield water that is considered soft. At Walnut Grove the village well and other wells between the depths of 150 and 325 feet supply soft water. Deep zones. — The water from the main artesian sandstone, which occurs at Marshall at a depth of about 400 feet, is extremely hard; it also contains large amounts of sodium and of sulphates and chlorine, and is very corrosive. No unmixed sample could be obtained from the well at the new mill, but its water also seems to be very hard. At Tracy the water from the depth of 600 feet is hard, but in general less highly mineralized than that from the deep sources at Marshall. It is significant that some of the deepest wells afford soft water, as is shown by analysis 10 in the table. A few of the wells reported to belong to this class are given in the following list: Partial list of deep " soft-ivater' ' wells in Lyon County, shoiving oivner, location, and depth. Feet. T. Jansen, SE. \ sec. 17, T. Ill N., R. 41 W a 422 Fred Mellenthine, SW. i sec. 9, T. Ill N., R. 42 W 530 B. Reese, SE. \ sec. 3, T. Ill N., R. 42 W 415 F. A. Revard, SW. i sec. 19, T. Ill N., R. 41 W 505 Andrew Silvius, NW. i sec. 6, T. 110 N., R. 41 W a 506 A., J., andE. Van Moer, NW. \ sec. 17, T. HON., R. 40 W 447 G.T.Walker, SW. \ sec. 18, T. Ill N., R. 41 W "433 a Todd, J. E., Water-Supply Paper U. S. Geol. Survey No. 102. p. 481. 248 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. PALEOZOIC AND ALGONKIAN ROCKS. Remnants of Paleozoic strata may exist; but if so, they are deeply buried and have not been recognized. The Sioux quartzite is certainly absent in most of Lyon County, but may be present in the southwestern part, though there is no evidence of it. Even if present, it is of no value as a source of water. ARCHEAN ROCKS. Granite or its decomposition products have been struck in drilling at Cottonwood, Ghent, and Minneota, and elsewhere north of Three- mile Creek and Redwood River, as well as at one point near the center of the county (NW. I sec. 6, T. 110 N., R. 41 W.), and at Tracy, in the extreme southern part. The data bearing on the depth of this rock below the surface and its elevation above sea level are shown in Plates III and XII. In most places where the granite is penetrated it is found to be much altered at the top, commonly being so thoroughly decayed that it is as soft as any clay. The following are some of the indica- tions of granitic residuum which every driller should understand: (1) Clays of brilliant red, yellow, green, white, etc.; (2) silvery flakes of mica; (3) angular, transparent grains of quartz; (4) hard, " glassy" layers alternating with softer material. These last are the quartzose bands of the original gneissic rock. In many localities there is a compact white formation consisting of kaolin or associated minerals derived from the underlying granite. In some places it has a sur- prising thickness, and contains interbedded seams of grit; such seams prove that it is not there a truly residual product, though resulting from the decomposition of the rock and nearly always lying upon it. (See the Minneota, Canby, and Tracy sections in PI. XII.) The granite is not water-bearing, except that rarely small supplies are developed in the upper part. WATER SUPPLIES FOR CITIES AND VILLAGES. Marshall. — The underground water conditions in Marshall have been fully described. The public supply is obtained chiefly from a combination dug and drilled well less than 100 feet in total depth. An artesian well 410 feet deep, and also the mill well and the river can be drawn on in case of fire. The combination well is reported to yield about 50,000 gallons a day, and the artesian well will flow at least 30,000 gallons in the same period. The water from the former is preferred to that from the latter because it is somewhat less highly mineralized. Analyses of both are given in the table (pp. 251-252). About 600 people use the public supply and on an average a Todd, J. E., Water-Supply Paper U. S. Geol. Survey No. 102, 1903, p. 481. LYON COUNTY. 249 approximately 40,000 gallons is consumed daily. About three-fourths of the inhabitants use water from private wells, most of which are less than 100 feet deep. The small supplies from the 250-foot soft- water zone are utilized in boilers and to some extent for culinary purposes. The water from the deep artesian sandstone is ruinous to boilers. Tracy. — There are in Tracy two principal sources of underground water, the glacial drift at depths of less than 200 feet, and the sand- stone stratum at 600 feet. The stratigraphic section is given in Plate XII. The deep well which furnishes the public supply has already been described. The analyses in the table show that its water is hard. About 50,000 gallons is used daily, and approximately 1,800 people are served. The Chicago and Northwestern Railway Company uses water from Lake Sigel for boiler purposes, and most of the people south of the railway are also supplied with this water. The private wells are dug, bored, or drilled, and range from a few feet to about 175 feet in depth, ending in glacial drift. The water in the shallow wells is considered poor. Minneota. — The entire supply for the village of Minneota comes from depths of less than 125 feet. The public supply is taken from a well 6 inches in diameter and 111 feet deep. It passes through glacial drift and below that through layers of "soapstone," sand, and sandstone, and is finished with an open end in a sandstone stratum. The water rises within 20 feet of the surface, or about 1,165 feet above sea level. About 7,000 gallons is consumed daily. All the we]ls in the village yield hard water. An analysis of the public supply is given in the table below. Softer water could prob- ably be obtained at a depth of 250 feet (PL XII). About 75 per cent of the people use water from private wells, many of which are bored to depths of less than 30 feet and end in glacial drift, but some are drilled into the Cretaceous sandstone. Cottonwood. — The granitic residuum at Cottonwood lies within 200 feet of the surface and is very thick. The glacial drift is 75 or 100 feet deep. Between the drift and the granitic material are strata of shale and sandstone. The entire population depends upon pri- vate supplies. There are only a few wells in the village, but most of the people have cisterns which are filled either with rain water or with water hauled from farm wells. The few private wells are of the dug or bored type and are about 20 to 40 feet deep. It is difficult to get water at shallow depths, but better supplies seem to occur between 100 and 150 feet below the surface. The railway well is 139 feet deep and ends in coarse sand yielding hard water. The creamery well is 160 feet deep and extends into white sand. The old mill well, now abandoned, was 152 feet deep and stopped in sand- stone that yielded water reported to be soft. It seems that all these 250 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. were successful wells. The well which was intended to supply the public waterworks was drilled to a depth of 375 feet, penetrating deep into the granitic rocks. It is cased to 175 feet and is said to get its meager supply from this depth. As the yield is very small and the water contains great quantities of sodium chloride (see the analysis given in the table), it is used only for fire protection. The well will soon be abandoned and water from the lake will be used. Balaton. — The public supply for the village of Balaton is taken from a well 8 feet in diameter and 27 feet deep. It passes through coarse gravel and is cased with stone. In 1907 the water stood about 13 feet below the surface, and pumping at the rate of 45 gallons a minute lowered it but slightly. It is moderately hard and supplies about 250 people, approximately 10,000 gallons being consumed daily. About one-half of the inhabitants use water from private wells. The dug wells are generally 20 or 30 feet deep and end in a thick bed of outwash gravel, but the drilled wells pass through blue bowlder clay and extend to sand and gravel layers at depths of 100 to 150 feet. The railway well is similar to the village well. The mill and creamery are supplied from drilled wells. FARM WATER SUPPLIES. On the lowland plain occupying the northeastern part of the county there are a few shallow bored wells that end in glacial drift, but these are generally unsatisfactory both in the quality and the quan- tity of the water that they furnish. For this reason by far the greater number of the farms here are supplied by drilled wells that tap the Cretaceous strata. Near the northern margin of the county these are commonly between 100 and 200 feet deep: northeast of Dudley they are generally 200 feet deep or less; in the vicinity of Marshall and thence southeastward between Dudley and Amiret to Redwood County there are many flowing wells between 300 and 500 feet deep, but also numerous shallower drilled wells. On the upland plain or coteau in the southwestern part of the comity the entire farm supply is derived from the glacial drift. Most of the wells are bored and are less than 100 feet deep, but there are also many drilled wells whose average depth is somewhat greater. On that part of the slope which is included in the Cretaceous flow- ing area numerous deep wells penetrate the artesian strata, but where flows can not be obtained virtually all the wells end in drift. SUMMARY AND ANALYSES. The facts in regard to the underground waters can best be sum- marized as follows: LYON COUNTY. 251 Underground water conditions in Lyon County. Area. Zones. Depth. Yield. Head. Quality. (Glacial drift Feet. to 100+.. 25 to 150... 150 to 230.. to 100.... 50 to 100 -200 to 300. 300 to 550.. to 300 None to moder- ate. Near sur- face. ...do Hard. Northern portion of lowland plain (north Shallow Cretaceous.. Intermediate Creta- ceous. Do. of Ghent, Dudley, and Milroy.) Southern portion of lowland plain and slope (approximate- ly coinciding with the Cretaceous flow- ing area (PI. IV), between Dudley, Ghent, Lynd, arid Tracy.) Southwe stern por- tion — the upland plain and that por- tion of the slope not Small to moder- ate. None to moder- ate. ...do ...do ...do ..do Rather soft. Hard. Shallow Cretaceous (absent in east ■ part). Intermediate Creta- ceous. Deep Cretaceous Do. Small to moder- ate. Moderate to large. . ..do -i- to -125. ( + ) Variable . . Low Soft. Varying, gener- ally hard. Hard. included in the Cre- taceous flowing area. (Southwest of Tracy, Lynd, and Min- neota.) [Cretaceous 300 to 1,000 (?) do Varying. Mineral analyses of water in Lyon County. [Analyses in parts per million.] Glacial drift and top of Cretaceous. Cretaceous. Depth feet. . Diameter of well inches.. Silica(Si0 2 ) Iron(Fe) Aluminum ( Al) Iron and aluminum oxides (Fe 2 03+Al 2 3 ) Calcium (Ca) Magnesium (Mg) Sodium and potassium(Na+ K) Carbonate radicle (CO3) Bicarbonate radicle (HCO3)... Sulphate radicle (SO,) Chlorine (CI) Nitrate radicle (NO3) Total solids 20 111 6 27 1.5 20 3.2 10 185 250 2 3.2 .13 1.8 250 1} 1.2 .15 2.5 300 2 2 :-n 2.1 312 6 12 178 75 103 436 559 26 1.167 3.2 142 70 205 .0 380 691 33 .0 1,370 207 89 126 563 657 6.8 1,387 163 74 134 439 604 1,230 26 306 95 24s 1,209 628 1,943 31 16 258 242' 378 52 836* 40 13 269 268 291 92 854' 59 20 524 325' 950 49 1, 793' 6.4 17 12 423 .0 268 709 23 .0 1,345 Depth feet. . Diameter of well inches.. Silica(Si0 2 ) Iron (Fe) Aluminum (Al) Iron and aluminum oxides (Fe 2 3 +Al 2 3 ) Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+ K) Carbonate radicle (CO3) Bicarbonate radicle (HCO3) - - - Sulphate radicle (SO<) Chlorine (CI) Nitrate radicle (NO3) Total solids Cretaceous— Continued. 422 li 2.8 Tr. 3.4 22 16 536 36l' 819 63 1,663' 11. 390 "22 329 97 676 1,279 51 2,449 485(?) 6 23 3 261 75 203 420* 935 40 1,789' 410 8 10 209 139 716 1,317 30 2,473 430 4* 2.06 324 99 387 1,679 47 2,774 600 10 to 6 16 4.4 138 36 283 645 39 1,244 600 "24 5 139 33 182 231 630 18 1,150 592 "s.3 3. 130 33 242 "296' 689 18 i.'m' Archean-Creta- ceous contact zone. 375(?) 6 and 8 5 3.8 38 32 934 85' 258 1,340 Tr. 2,669 3 89 69 611 254 778 580 252 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. 1. Well at Minneota. 2. Village well at Minneota. August 23, 1907. 3. Wellof the Chicago and Northwestern Railway Company at Marshall. May, 1900. 4. City well at Marshall from which the public supply is usually taken. August 12, 1007. 5. We'll at Tracy. October 28, 1SS0. 6. Well at the Marshall Bottling Works. November 12, 1908. 7. Well of H. H. Adair at Marshall. November 12. 190S. S. Well of C. H. Middleton, near Marshall, in the SE. i sec. 3, T. Ill N., R. -11 W. November 12, 1908 9. Village well at Walnut Grove (Redwood County). 10. Welfof T. Jansen, near Marshall, on the SE. i sec. 17, T. Ill N., R. 41 W. November 12, 190S. 11. Flowing well at the old mill in Marshall. March 0. 1S90. 12. City flowing well at Marshall. August 12, 1907. 13. Flowing well at Marshall. April 28, 1902. 14. Flowing well of the Chicago and Northwestern Railway Company at Marshall. February 13, 1903. 15. City well at Tracv. August 13, 1907. 16. City well at Tracy. August 26, 1896. 17. We'll at Tracv. March 0, 1881. IS. Village well at Cottonwood. August 21, 1907. 19. Flowing well on the property of W. A. Rush at Minneota. August 23, 1907. Analyses^, 4, 0, 7, S. 9, 10, 12, 15, IS. and 19 were made for the United States Geological Survey by H. A. Whitta'ker, chemist Minnesota state board of health. Analyses 1. 3, 5, 13, 14, and 17 were furnished by G. M. Davidson, chemist, Chicago and Northwestern Railway Company. Analyses 11 and 16 were fur- nished by Edgar & Mariner, chemists. Chicago. McLEOD COUNTY. By O. E. Meinzer SURFACE FEATURES. The surface of McLeod County consists of a gently undulating plain which is covered with many swamps and small lakes. The principal streams are Buffalo Creek and South Branch of Crow River, both of which flow eastward across the county. They occupy shallow valleys and have accomplished but little postglacial erosion. SURFACE DEPOSITS. Description. — The glacial drift occurs in all parts of the county and its average thickness is great. Older formations nowhere come to the surface, and they have been reached in only a few wells. In the city well at Glencoe the drift was found to be at least 2S0 feet thick and possibly 354 feet.° At Brownton it has been penetrated to a depth of 304 feet; at Stewart to a depth of 265 and perhaps 320 feet, and on a farm south of Stewart to a depth of 375 feet, without apparently reaching the bottom. In the village of Buf- falo Lake, 6 miles west of this county, it was found to be about 340 feet thick. At Hutchinson it has been penetrated to a depth of 230 feet, and in several wells between that city and Brownton to depths of more than 300 feet, without reaching the bottom, and in a well near Lester Prairie the underlying rock was entered 360 feet below the surface. Yield of water. — The drift yields generous quantities of water, the deepest sand and gravel beds especially furnishing large and permanent supplies. The 10-inch flowing well at the flouring mill in Hutchinson, a This statement is based on the correlations made by Prof. C W. Hall. A different interpretation is given by Wan-en Upham. See Final Rept. Geol. and Nat. Hist. Survey Minnesota, vol. 6, 1900, oppo- site PI. 37. McLEOD COUNTY. 253 about 180 feet deep, has been pumped at the rate of 800 gallons a min- ute, and when given a head of 6 feet it will flow 200 gallons a minute. The 6-inch village well at Brownton, reported to be 304 feet deep, has been tested with an air lift at the rate of 95 gallons a minute. The 8-inch village well at Stewart, 320 feet deep, appears to have a less generous yield. According to report it "will supply 60 gallons a minute when the pump is placed 107 feet below the water in the well, but fails to furnish this amount when the pump is only 87 feet below the water level. Head of the water. — Flowing wells can be obtained in the valley of South Branch of Crow River all the way from Otter Lake to Lester Prairie (PI. IV) . The water from various sand and gravel beds will come to the surface, but the strongest artesian zone lies at a depth of about 200 feet. Several flowing wells are found east and north of Otter Lake and in the valley leading eastward from this lake. In the city of Hutchinson there are about 55 flowing wells which range in depth, according to their surface altitudes, between 180 and 210 feet. In the well at the mill, situated on the bank of the river, the water is under sufficient pressure to rise 28 feet above the surface, or to a level 1,055 feet above the sea. In wells located upon ground higher than about 1,055 feet above sea level the water does not come to the surface. A few flows have been obtained from a 45-foot seam which has about the same head as the 200-foot zone, and flows of very slight yield are obtained from a depth of about 170 feet. Not many flowing wells have been drilled in the valley between Hutchinson and Biscay, but there are several in the vicinity of Biscay, and some at various points along the valley to Koniska and beyond. At tbe village of Biscay the water will rise about 20 feet above the surface, or approximately 1,040 feet above sea level. At Lester Prairie, on the north side of South Branch near the point where that stream flows out of the county, the water from a 100-foot zone and also from lower beds comes virtually to the surface, which is here 980 feet above sea level. Flows could probably be secured on the river bottom all the way from Koniska to Lester Prairie. On the west side of Lake Marion (T. 115 N., R. 30 W.) there are several flowing wells about 100 feet deep; in the valley of Buffalo Creek the water rises virtually to the surface and in a few wells over- flows with a slight head. The head decreases toward the southeast, away from the high morainic area, which is in large measure the cause of the artesian conditions. This fact is made clear by the following table showing the head to which the water from the drift rises in the various localities in. the county. 254 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Height to which water rises from the glacial drift in McLeod County. Locality. Above (+)or belo\v(— ) surface. Above sea level. Feet. +28 +22 -13 -24 -30 Feet. 1,055 1,040 980 1,045 995 970 Quality of the water. — In this region there is both a vertical and a horizontal variation in the mineral character of the water from the glacial drift. In general, the hardness decreases from the west east- ward, and from the upper portion of the drift downward. Thus the shallow drift water is not as hard in this county as in Renville County, but in both counties it is harder than the average water from the deep drift zones. (See the analyses in the table on pp. 257-258.) FORMATIONS BENEATH THE GLACIAL DRIFT. Description. — Nearly all that is known about the formations beneath the glacial drift is derived from the record of the deep well which was sunk for the city of Glencoe in 1897. The drillings of this well were preserved by Mr. T. M. Paine, of Glencoe, and were examined and described by Prof. C. W. Hall and Prof. J. A. Partridge of the Univer- sity of Minnesota. The following is the section given : Section of the deep well at Glencoe. Thick- ness. Depth. Feet. Feet. 3 3 78 81 67 148 39 187 38 225 55 280 10 290 20 310 43 353 1 354 56 410 134 544 34 578 14 592 10 602 218 820 54 874 62 936 139 1,075 565 1,640 Soil Gravel and sandy clay Blue clay ' Gravelly clay Uniform sand with streaks of clay Gravel and sand Blue shale Gray sandy shale Gray uniform sand A drift conglomerate Gray shale, grading into red White sand Pink sand, grading nearly to white and showing evidence of consolidation White sand, grading into pink Light-gray sand Pink sand , toward the bottom becoming highly colored White sandstone, varying to pink Pink sandstone Red shale and sandstone of uniformly persistent color Red to pink shale and sandstone , with but little variation (no samples) . . This well extends 645 feet below sea level without encountering granite, and penetrates at least 1,286 feet of stratified formations. If the section (below the drift) includes Cretaceous, Paleozoic, and Algon- ]kian strata, it probably represents several distinct systems separated McLEOD COUNTY. 255 by unconformities. At Buffalo Lake, 6 miles west of McLeod County and 23 miles west of Glencoe, granitic rock is reached at about 340 feet below the surface, or 725 feet above sea level, and there are no stratified rocks present, the glacial drift resting immediately upon the granite. All the stratified formations in the Glencoe section therefore disappear before reaching Buffalo Lake. Yield of water, — The section of the deep well at Glencoe consists largely of water-bearing sandstones. The beds lying between the depths of 310 and 354 feet yielded some water, but a larger supply came from the sandstones below 410 feet. The well is now cased to a depth of 385 feet, below which it is open. With the pump placed 100 feet below the surface, or about 10 feet below the normal level of the water, it has been tested at the rate of about 175 gallons a minute for thirty-six hours continuously. It is also reported to have been tested at 150 gallons a minute with the pump inserted only 2 feet below the water level. In the 8-inch railway well at Glencoe, which is 566 feet deep, pumping at the rate of 115 gallons a minute lowered the water about 1 foot. Head of the water. — The deep well at Glencoe was drilled for the purpose of obtaining a flow, but this project failed. At first the water rose to a level 115 feet below the surface, or 880 feet above the sea — about the height to which it now rises in the 566-foot railway well. At a greater depth the water came within 90 feet of the surface, or 905 feet above sea level, which is the head at the present time. The view is held by some of the people that the water from the lower strata would rise higher if the well could be tightly cased, so that the deep water coming up through the well could not leak out into the upper formations. This theory is based on a sound principle too often ignored in drilling artesian wells; but the altitude at this point makes it virtually certain that the water would not rise to the surface from any horizon penetrated in the Glencoe well. Quality of the water. — The mineral character of the water from the Paleozoic sandstones is shown by the three analyses, given in the table on page 258, of samples taken from the deep Glencoe well. This water does not differ greatly from that of the lower portions of the drift, except that it is somewhat higher in the alkalies, sulphates, and chlorine. WATER SUPPLIES FOR CITIES AND VILLAGES. Hutchinson. — The public supply and nearly all of the domestic and industrial supplies at Hutchinson are obtained from the strong artesian layer that occurs at a depth of about 200 feet. This zone is so satisfactory that drilling to greater depths has never been under- taken. It gives rise to flows in all parts of the city except the south- western, where the altitude is greatest. The well at EL H, Ames's 256 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. flouring mill, which is described above (p. 252), furnishes the public supply, the city being given the use of the water free of charge. This well was drilled about twenty years ago and there appears to be no diminution in the pressure. The analysis contained in the table shows that the water is moderately hard. About 33,000 gallons is consumed daily. Glencoe. — The public supply in Glencoe is taken from the 1,640- foot well, which has been fully described. About 1,000 peoj)le use the water, and 125,000 gallons is daily consumed. Approxi- mately one-half the inhabitants, however, rely upon private wells, only a few of which are drilled to any considerable depth. The brewery well is 224 feet, the creamery well 230 feet, and the railway well 566 feet deep. Several analyses of water from this vicinity will be found in the table on pages 257-258. Brownton. — The glacial drift in the locality of Brownton is known to be thick, but no definite section is available. The village well is 304 feet deep and ends with a screen in a bed of gravel. Its head and yield are given above. The water is relatively soft, as is shown by the two analyses given in the table. It is used by nearly all the people, and the daily consumption averages about 4,000 gallons. Stewart. — At Stewart the section, to a depth of -at least 320 feet, consists of bowlder clay with interbedded layers of sand and gravel. The best water zones seem to be found below 265 feet. The well which furnishes the public supply ends with a screen in one of these deeper beds. The data in regard to this well have already been given (pp. 253-254). The water, an analysis of which will be found in the table, is softer than that from the more shallow wells. About 20,000 gallons is consumed daily, but most of this is taken by the railway company, for nearly all the people, perhaps 90 per cent, use water from private wells. Lester Prairie. — The village of Lester Prairie is located on the north side of Crow River on a level terrace underlain by alluvial sand and gravel, which extends to a depth of about 30 feet and is saturated with water nearly to the surface. Beneath the alluvium is the ordinary glacial drift, consisting of blue clay and sandy seams from which the water rises virtually to the surface, or 980 feet above sea level. North of the village, at a somewhat higher altitude, stretches the gently undulating drift plain which comprises most of the county. The public waterworks are supplied from a well 20 feet in diameter, which ends in the alluvial deposits at a depth of 22 feet. In 1907 the water stood 8 feet below the surface, and pumping at the rate of 200 gallons a minute was reported to empty the well in about one hour. The water is rather hard, as is shown by the analysis given in the table below. Only a small amount is consumed. Near all the people use water from private wells, which are driven into the alluvium and yield generously, though on an average less than 20 feet deep. McLEOD COUNTY. 257 Silver Lake. — The domestic supply at Silver Lake is obtained chiefly from bored wells between 20 and 65 feet deep. The public waterworks are supplied from the lake. Winsted. — In Winsted village, as in Silver Lake, the domestic supply is derived mainly from bored wells less than 100 feet deep, but the public waterworks are supplied from the lake. FARM WATER SUPPLIES. At one time virtually all the farm wells were bored or dug, and most of them are still of this type. They are shallow and yield varying quantities of hard water. Gradually they are being replaced by drilled wells, especially in the vicinities of Glencoe, Brownton, Bis- cay, and Hutchinson. The drilled wells are generally 2 inches in diameter and range from less than 75 to more than 300 feet in depth, most being between 100 and 200 feet. SUMMARY AND ANALYSES. The deposits of bowlder clay, which are everywhere several hundred feet thick, contain numerous layers of sand and gravel, the deepest of which yield large and permanent supplies. In general, the water from the lowest beds is the softest and least liable to incrust the screens placed in the wells,, but there are exceptions to this rule. Flows are obtained only in certain low areas. In the eastern portion there are thick formations of sandstone, and it is probable that these occur, at least in part, throughout most of the county, at depths of 400 to 600 feet and more. They will furnish large quantities of only moderately hard water, but will not give rise to flows at any point in this county. Mineral analyses of water in McLeod County. [Analyses in parts per million.] Surface deposi ts (glacial drift etc.). 1. 0. 3. 4. 5. 6. 7. 8. 9. 10. 11. Depth feet. . Diameter of well . . . inches . . 21 120 22 28 Tr. 22 240 31 . 2 28 144 39 144 40 84 112 2 115 120 172 3 180 10 Silica (Si0 2 ) 22 Iron(Fe) 5 Aluminum ( Al) Iron and aluminum oxides (Fe 2 03+Al 3 03)... 3.3 78 24 5 8 149 50 37 .0 547 117 54 12 740 .8 136 44 61 .0 415 110 130 4.2 731 4.7 113 46 10 6.2 112 49 20 7 76 24 5 8.4 96 43 54 7.4 88 38 45 6.4 96 42 56 12 117 42 39 103 39 Sodium and potassium (Na+K) 29 Carbonate radicle (CO3) .0 Bicarbonate radicle (HCO3) . Sulphate radicle (SO4) Chlorine (CI)... . 330 27 3.2 484 65 19 516 61 27 307 41 3.6 540 79 4 572 10 1.5 560 71 3 628 28 2 512 67 2 Nitrate radicle (NO3) .0 Total solids 303 496 529 308 550 467 550 549 531 60920°— wsp 256—11 17 258 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Mineral analyses of water in McLeod County — Continued. Surface deposits (glacial drifts, etc.)— Continued. 12. 13. 14. 15. ' 16. 226 Depth feet. Diameter of well inches. Silica(Si0 2 ) ' 24 Iron(Fe) 2.8 Aluminum (Al) 4.9 Iron and aluminum oxides (Fe 2 3 +Al 2 03) Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+K) Carbonate radicle (CO3) Bicarbonate radicle (HCO3) . Sulphate radicle (SO*) Chlorine (CI) Nitrate radicle (N0 3 ) Total solids 230 3 117 48 28 647 65 1 568 609 230 2 260 3 120 51 1.2 40 23 304 304 320 6 6 8 29 26 686 I 503 54 ; 512 20 49l' 3.1 75 34 75 588" ' "s " 48i" 3.2 42 10 440 24 1.3 449 Paleozoic sandstones. 1,(140 5 and 6 1.7 78 40 456 107 35 1,640 I 1,640 SandO 8and6 8.8 .5 4.7 429 116 37 .0 600 1.2 75 33 464 158 165 870 1. Well at Hutchinson. November 24, 1897. 2. Well of Lee Arnold at Brownton. September 17, 1907. 3. Village well at Lester Prairie. September 19, 1907. 4. Well at Glencoe. September 3, 1888. 5. Well at Glencoe. May 3, 1888. • 6. Well at Hutchinson. October 13, 1888. 7. Well at the flouring mill at Brownton. December 5, 1894. 8. Well at Brownton. December 5, 1894. 9. "Bullick's well" at Brownton. December 5, 1894. 10. Mr. Hayden's well at Glencoe. April 22, 1895. 11. Flowing well at the flouring mill at Hutchinson. This well furnishes the public supply. Septem- ber 18, 1907. 12. Flowing well on the farm of William Conrad, NE. \ sec. 31, T. 116 N., R. 28 W. One and one-half miles east of Biscay. September 18, 1907. 13. Creamery well at Glencoe. May 9, 1895. 14. "Bretchet's well" at Glencoe. May 9, 1895. 15. Well at Stewart. March 3, 1896. 16. Village well at Brownton. September 17, 1907. 17. Village well at Brownton. October 3, 1895. 18. Village well at Stewart. September 14, 1907. 19. City well at Glencoe. July 21, 1898. 20. City well at Glencoe. September 17, 1907. 21. City well at Glencoe. July 17, 1897. Analyses 2,3, 11, 12, 16. 18, and 20 were made for the United States Geological Survey by H. A. Whittaker, chemist Minnesota state board of health. Analyses 1,4,5,6,7,8,9,10,13,14,15,17,19* and 21 were furnished by G. N. Prentiss, chemist Chicago, Milwaukee and St. Paul Railway Company. MARTIN COUNTY. By O. E. Meinzer. SURFACE FEATURES. The surface of Martin County constitutes a gently undulating and poorly drained upland plain with no notable irregularities except in the morainic belt southeast of Fairmont. It descends from an altitude of about 1,400 feet above sea level in the southwestern corner to about 1,100 feet in the northeastern, the slope being quite imper- ceptible, but nevertheless sufficient to affect in an important way the head of the underground waters. Most of the numerous lakes in this county are arranged in three nearly parallel chains, apparently occurring along the lines of a preglacial river system which drained the region toward the south. a At present the drainage system is entirely different. Elm Creek, Center Creek, and South Creek flow aUpham, Warren, Final Rept. Geol. and Nat. Hist. Survey Minnesota, vol. 1, 18S2, p. 479. MARTIN COUNTY. 259 eastward and discharge into Blue Earth River a few miles beyond the county line; East Fork of De Moines River, rising along the west- ern margin of the county, flows across the southwestern corner; and several small streams rising in the northern part flow northward into Watonwan River. These streams have shallow valleys and but few tributaries, thus leaving most of the upland prairie untouched by erosion. SURFACE DEPOSITS. Description. — The glacial drift, which consists of bowlder-clay and interbedded seams of sand and gravel, forms a continuous mantle over all of this county. As the underlying formations have seldom been reached in drilling, even in wells between 200 and 300 feet deep, it is certain that the drift sheet is generally thick, but there is a corresponding uncertainty as to its actual thickness. Moreover, there is evidence that the surface on which the drift rests is irregular, causing corresponding irregularities in the thickness of the drift sheet itself. Ancient valleys seem to have been cut into the underlying formations, and the drift is unusually deep where these valleys existed. In general it is most attenuated in the eastern part and increases in thickness toward the southwest. Its average thickness for the entire county is probably between 200 and 300 feet. Yield of water. — The water-bearing portions of the drift can be divided into two rather distinct groups: (1) Gravelly deposits associated with the surficial yellow clay above the impervious blue clay, and (2) layers of sand and gravel interbedded with the blue clay or lying at its base. Few of the former deposits are more than 40 or 50 feet below the surface. Because of their imperfect porosity and the slight pressure to which their water is subjected, the yield is commonly small; and because of their surficial position the supply is readily affected by the season and may fail entirely in times of drought. The second group of deposits occur at various depths and have a wide range in thickness, porosity, and water-yielding capacity. Occasionally a well is drilled that passes through no bed sufficiently thick and coarse to furnish an adequate supply, but such wells are exceptional. In nearly every locality are found one or more sandy beds that will yield at least as much water as an ordinary windmill is capable of pumping. The village well at Sherburn, which ends with a 6-inch bore in a 10-foot stratum of sand at a depth of 248 feet, was pumped, immediately after its completion, at the rate of 160 gallons a minute for a continuous period of about six hours without noticeably lowering the water. Head of the water. — The water in the sand and gravel beds is always under pressure, and hence rises in the wells which tap them. 260 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. The following table shows the surface altitude and the height to which the water rises above sea level in different parts of the county : Table showing approximately the head of the water from deep-drift zones in Martin < 'ounty. ' j i Altitude T „„ lllit „ Altitude to which ^ ocam >- of surface.! water rises. Feet. Sherburn 1,295 Ceylon . Welcome.. Triumph.. Fairmont. Granada.. 1,260(?) 1,243 1,230 1,195 1, 133 Fret. 1,215 1,200(?) 1,501 1 , 130 1,130 1,100 In the extreme western and southwestern parts of the county, where the surface is more than 1,300 feet above sea level, the water from the deeper beds in the drift commonly fails to rise within 100 feet of the surface; throughout most of the western half of the county, where the surface is between 1,200 and 1,300 feet above sea level, the water stands somewhere between 50 and 100 feet below the sur- face. On the other hand, in the eastern and northeastern parts, where the surface is between 1,100 and 1,200 feet above sea level, the water usually rises within 50 feet of the surface, and in the valleys of Center, Elm, and Perch creeks, which are depressed slightly below the 1,100-foot level, flowing wells with slight pressure occur. Flows can be obtained (1) in the vallej^ of Center Creek from the county line upstream above Granada; (2) in the valley of Elm Creek from the county line upstream to sec. 35, T. 104 N., R. 30 W., and possibly still farther; (3) in the valleys of the two small branches which join Elm Creek in sec. 5, T. 103 N., R. 29 W.; and (4) near the headwaters of Perch Creek. Sixteen flowing wells were noted in the portion of Center Creek valley that lies in this county, and 23 in the portions of Elm Creek valley within the county. It is probable that there are a few others that were not noticed. In an area of relatively low altitude, such as the eastern part of this county, the waters from the various zones (whieh occur at dif- ferent depths and are apparently separated b}" layers of impervious clay) usually rise very nearly to the same level, the water from the deep zones is likely to be lifted slightly higher than that from the shallow ones. Thus on the farm of W. R. Benton, sec. 5, T. 103 N., R. 29 W., in a well drilled to a depth of 198 feet, beds of water-bearing sand or gravel were encountered at depths of 50, 110, 150, and 190 feet. All these produced flows, but from none did the water rise more than a very few feet above the surface. Likewise, in W. H. Thomp- son's flowing well at Granada water-bearing beds were encountered at depths of 50, 75, and 107 feet. From the first the water rose 2 feet above the surface; from the second, 2 feet above the surface, MARTIN COUNTY. 261 and from the third, 6 feet above the surface. In a region of rela- tively high altitude, on the other hand, such as the western part of this county, the water generally rises higher from shallow sources than from the deeper ones; this fact-could be illustrated by numerous examples. Quality of the water. — All the waters from the drift have a high content of calcium, magnesium, and. sulphates, and therefore have a great permanent hardness and form hard scale in boilers. There are however, considerable differences in the degrees of mineralization, even in the same locality, as is shown in the analyses contained in the accompanying table. UNDERLYING FORMATIONS. Description. — As there are no rock outcrops in this county and only a small number of wells that penetrate formations older than the drift, the geologic structure is largely a matter of conjecture. How- ever, it seems probable that Cretaceous, Paleozoic, Algonkian, and Archean rocks are all present and are separated from each other by pronounced unconformities. The evidence in regard to the presence of the Cretaceous can be summarized as follows : West of Martin County there are many wells that apparently end in Cretaceous rocks and a few in different parts of this county have penetrated strata of shale, sand, and sandstone which appear to belong to this series; but there is no reliable evidence of Cretaceous rocks in Faribault County to the east. Furthermore, there is considerable evidence that the Cretaceous exists south of the western and central parts of Martin County but is absent south of the eastern part. Alternating layers of shale, sand, and sandstone, which appear to belong at least in part to the Cretaceous, have been penetrated at Estherville, Iowa, and at Kingsted, Iowa, south of the western and central portions of this county, respectively; but a short distance east of Ringsted wells encounter indurated Paleozoic limestones without passing through anything that could be inter- preted as Cretaceous. Likewise, north of the central and western parts a number of wells have been drilled which pass through a con- siderable thickness of soft shale, sand, and sandstone, apparently continuous with the great body of Cretaceous sediments to the west. It therefore appears probable that in the eastern portion of Martin County Cretaceous deposits are absent or very thin, but that in the western portion they are continuous and attain a greater thickness. At Blue Earth, 8 miles east of the county line, at least 800 feet of Paleozoic strata lie below the glacial drift and extend downward nearly to sea level; at Mountain Lake, 7 miles northwest of Martin County, the Sioux quartzite, which is referred to the Algonkian sys- tem, lies immediately beneath the drift at an altitude of 1,237 feet 262 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. above sea level. Thus, in a distance of 45 miles from Blue Earth across Martin County to Mountain Lake, all the Paleozoic formations from the Galena limestone downward terminate and the underlying surface rises from near sea level to 1,237 feet above sea level. The Paleozoic formations no doubt dip gently toward the southeast, and so if the glacial drift and Cretaceous deposits were removed they would probably be seen outcropping in parallel northeast-southwest trending belts, the oldest formations lying next to the Sioux quartzite, and successively younger formations coming to the surface toward the southeast. Several wells have penetrated a fine-grained gray or white sand- stone, and a well just south of the SW. \ sec. 35, T. 101 N., R. 31 W., passed entirely through this sandstone which was here found to be 100 feet thick. It is possible that the formation in question belongs to the Cretaceous sandstone that occurs at Emmetsburg, Iowa, a but more probably it belongs to the St. Peter sandstone, which was found to be 91 feet thick at Blue Earth. The formations older than the St. Peter are not known to have been penetrated in drilling in this county. At Blue Earth the Paleozoic rocks consist chiefly of alter- nate formations of sandstone and limestone, but it is probable that in Martin County, where the ancient shore is approached, the lime- stones give way in part to shales and sandstones. As has been ex- plained in the report on Faribault County, there is no evidence that the Carboniferous extends into Minnesota. Yield, head, and quality of the water. — At no great depth beneath the glacial drift occur the Cretaceous and Paleozoic sandstones which have just been discussed. Though they have not yet been explored in this county, there is no doubt that they will furnish large supplies of water, except possibly in the northwestern corner. There is little probability that flowing wells can be obtained from the deep beds of this county, but the water may generally be expected to rise about as high as that from the lower portion of the drift. In the northern and eastern parts it will come near the surface, but in the high area comprising the southwestern part it will remain at a depth of more than 100 feet. At Blue Earth the water rises within 32 feet of the surface, or 1,050 feet above sea level; at St. James, within 32 feet of the surface, or 1,053 feet above sea level; in the sandstone wells in this county, within 50 or 100 feet of the surface; and at Estherville, Iowa, within 120 feet of the surface, or about 1,165 feet above sea level. It is probable that the deep water is as hard or even harder than that from the glacial drift. (See the reports on Watonwan and Fari- bault counties.) a Norton, W. H., Ann. Rept. Geol. Survey Iowa, vol. 3, 1S92, pp. ISO and 187. MAETTN COUNTY. 263 WATER SUPPLIES FOR CITIES AND VILLAGES. Fairmont. — Fairmont is situated just east of Center Chain of Lakes in a locality characterized by an irregular morainic topography. The following log of the new well at the high school presents a typical section of the upper portion of the glacial drift, the total thickness of which is here rather great. Well section at Fairmont. [Authority, Brown & Wilkins, drillers, Fairmont.] Thick- ness. Depth. Soil Yellow clay. Blue clay — Gravel Feet. 3 20 87 3 Feet. 3 23 110 113 The public waterworks are supplied from Lake Budd. About 1,500 people use the water, and it is also used in the locomotives of the railway companies. Altogether about 120,000 gallons is con- sumed daily. Nearly all the people use water from private wells for drinking and culinary purposes. Most of the private wells are 2 inches in diameter and end in beds of sand and gravel at various depths, most of them being between 60 and 100 feet deep. There are also some shallow bored and dug wells. The ground water is hard, as is shown by the analyses given in the table (p. 265). Sherburn. — West Chain of Lakes lies just east of Sherburn vil- lage. The glacial drift is here at least 250 feet thick. The section reported for the village well is as follows: Well section at Sherburn. [Authority, William Tenhofl, superintendent of public waterworks, Sherburn,] j Thick- ness. Depth. Yellow clay , Feet. 20 Feet. 20 Blue clay 110 130 Sand 4 134 104 238 Sand.. .'. m 248 Blue clay (entered). The data in regard to this well have already been given. The analysis in the table (p. 265) shows that the water is not so highly mineralized as much of the water in this region. The public supply is used by about 250 people, and approximately 13,000 gallons is consumed daily. At least 75 per cent of the inhabitants rely on private wells, which are generally shallow and provide small quanti- ties of water. There are, however, a few drilled wells, the deepest of 264 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. which yield abundant and permanent supplies. The railway com- pany takes water from Temperance Lake; the creamery is supplied from a well 180 feet deep; and at the mill the public supply is used at present. Welcome. — In many parts of the village of Welcome sand and gravel are found at depths of 20 to 40 feet, beneath which there is blue clay to about 150 feet. Other layers of sand occur below this depth. The public waterworks are at present supplied from a com- bined dug and drilled well that reaches to the 150-foot sand stratum, but because of faulty construction its yield is not great. Nearly all the people use water from private wells, most of which are bored or dug to depths of 20 to 40 feet and end in the deposit of sand and gravel mentioned above. In some parts of the village this deposit is absent, and wells are drilled to the deeper beds or get meager supplies from sandy seams at intermediate levels. In the table below analyses are given of the public supply and of water from the mill well, which is 40 feet deep. Ceylon. — The waterworks at Ceylon are supplied from a drilled well 8 inches in diameter and 300 feet deep. Pumping from this well at the rate of 100 gallons a minute is said to produce no noticeable effect. Nearly all the people use water from private sources. The dug and bored wells end in yellow clay at depths of about 20 to 40 feet and furnish moderate supplies; the drilled wells are deeper and yield more abundantly. Truman. — The village of Truman has a system of public water- works supplied from an 8-inch well, which is 104 feet deep and in which the water rises virtually to the surface. The inhabitants depend almost entirely on private wells. FARM WATER SUPPLIES. There are two types of wells corresponding to the two groups of water-bearing beds in the drift mentioned above (p. 259) — (1) shallow bored or dug wells, which are generally less than 40 feet deep and end in yellow clay or sandy deposits above the impervious blue clay ; and (2) drilled wells, with iron casings, which end in strata of sand and gravel interbedded with the blue cla}^. The yield from first type of wells is generally small and uncertain; it is brought to a maximum by making the wells of large diameter, with casings of wood or tile that will admit water at all depths. When the county was first settled these wells were depended on entirely, but they were found to be unreliable in dry years and to be otherwise unsatisfactory. The drilled wells range in depth from about 50 to 300 feet, but are generally between 75 and 175 feet. Their average depth is greatest in the western and southwestern parts of the county, where wells MARTTN COUNTY. 265 between 200 and 300 feet deep are not rare, and least in the eastern and northeastern parts, where the average depth is perhaps not more than 100 feet. The yield is generally large and is not seriously affected by drought. Most of the wells are only 2 inches in diameter and are finished with screens, which cause much trouble by becoming incrusted. Wells of such small diameter should not be drilled in this county except where flows are expected. '■ SUMMARY AND ANALYSES. The deeper beds of sand and gravel in the drift furnish adequate supplies for all ordinary purposes and will probably always be the chief source of water. At greater depths lie sandstones which will yield copiously but whose water will rise no higher than that from more shallow sources, so that virtually no hope is offered that flows could be obtained in them. Moreover, much of the water from deep beds is very hard, and there is no evidence that any of it is softer than that now used from the more shallow beds. Mineral analyses of water in Martin County. [Analyses in parts per million.] Depth feet.. Diameter of well Silica (Si0 2 ) Iron (Fe) Iron and aluminum oxides (Fe203+ A1 2 3 ) Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+K) Carbonate radicle(C03) Bicarbonate radicle (HC0 3 ) Sulphate radicle(S0 4 ) Chlorine (CI) Nitrate radicle (NO3). Total solids Surface deposits (glacial drift, etc.) 322 100 5so 19 1.5 7 181 28 466 425 6 70 2 24 2.6 5.1 140 54 .0 259 3*9 4 1.5 772 100 2 210 61 .529 524 5 1,158 90 4.1 197 58 496 556 3.6 1,182 150 Large 23 1 3.3 137 67 495 367 47 4 1,018 185 2 212 59 468 SON 3 1,522 248 2.5 117 32 307 233 4 (?) 11. 12. 13 205 2.1 121 47 10] 415 23.5 296 6,4 186 58 49 454 415 4 %>,:> 404 6 9 218 466 598 3 1. Railway well at Fox Lake on the shore of the lake. September 20, 1899. 2. Mill well at Welcome. September 20, 1901. 3. Flowing well on the farm of M. E. Davidson, NE. \ sec. 28, T. 103 N., R. 29 W. July 15, 1907. 4. Well of George Clynick, SW. J sec. 33, T. 104 N., R. 29 W. July 15, 1907. 5. Well at the livery stable at Granada. September 20, 1901. 6. Former well of the Chicago, Milwaukee and St. Paul Railway Company at Fairmont. November 2 1892 ' 7. Well at Fairmont. October 25, 1888. 8. Village well at Welcome. July 23, 1907. 9. Former village well at Welcome. September 20, 1901. 10. Village well at Sherburn. July 23, 1907. 11. Village well at Sherburn. November 15, 1895. 12. Village well at Sherburn. June 30, 1899. 13. Village well at Sherburn. July 23, 1901. 14. Former city well at Fairmont. March 21, 1894. Analyses 3, 4, 8, and 10 were made for the United States Geological Survey by H. A. Whittaker, chemist Minnesota state board of health. Analyses 2, 5, 6, 7, 9, 11, 12, 13, and 14 were furnished by G. N. Pren- tiss, chemist Chicago, Milwaukee and St. Paul Railway Company. Analysis 1 was furnished by 6. M. Davidson chemist Chicago and Northwestern Railway Company. 266 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. MEEKER COUNTY. By O. E. Meinzer. SURFACE FEATURES. The surface of Meeker County presents the following three types of topography, which correspond to different underground water con- ditions: (1) The irregular, morainic relief that characterizes most of the county; (2) the gently undulating surface that occurs only in the southern part; and (3) the large, sandy plain in the center of the county and similar smaller level areas. North Branch of Crow River crosses the northern and South Branch the southern part of the county, both draining toward the Mississippi. They have few tributaries and the surface is but imperfectly drained. SURFACE DEPOSITS. Description. — The glacial drift consists of impervious bowlder clay and beds of sand and gravel. The sand and gravel beds are inter- mingled with the clay in various ways, and in this county are espe- cially prominent at the surface in the level tracts already mentioned. The drift covers the entire county, no outcrops of older rocks being known, but so few deep wells have been drilled that there is little information on which to base an estimate of its thickness. At Eden Valley underlying formations have been encountered at a depth of 200 feet, and in several other localities in the northern part at depths of 100 to 200 feet; 6 miles north of this county the rocks come to the surface. In the southern part the drift is thicker, how- ever, so that the average for the county is perhaps not far from 250 feet. Yield of water. — The porous beds of sand and gravel are usually saturated with water which they give up readily. Thin deposits near the surface are liable to fail in dry years, but those which lie at greater depths, as well as the thick beds at the surface, are little affected by drought. Head of the water. — The irregular, morainic topography of a large part of this country is likely to give rise to small areas in which flow- ing wells with slight pressure can be obtained. Such areas are usu- ally found on the lowest ground near streams and lakes, at the foot of high, morainic belts. There are several flowing wells on the hill- side north of Eden Valley, and others could probably be obtained from the same zone in the village. A few are found along North Branch of Crow River in the vicinity of Forest City, between Eden Valley and Litchfield ; one has been reported on the east side of Swan Lake, northeast of Dassel, and another west of Stella Lake, about 4 a Upham, Warren, Final Rept. Geol. and Nat. Hist. Survey Minnesota, vol. 2, 1885, pi. 40. MEEKER COUNTY. 267 miles west of Darwin. There are also several on the low ground between Strout and Rosendale, south of Grove City. 'Flowing wells could no doubt be obtained in other depressed localities. Quality of the water. — The underground waters differ chiefly in the quantity of sulphates which they contain. In this important respect they differ widely, but in a systematic manner, as is shown by the table of mineral analyses (p. 271). The water from shallow sources contains a large amount of sulphates associated with much calcium and magnesium, so that it has a permanent hardness and produces hard scale in boilers; but the water from the deeper sources contains only small quantities of sulphates, with less calcium and magnesium, and will form less hard scale. This second type is found nearer the surface in the northern than in the southern part of the county. The shallow water is all hard, but that from the sand and gravel interbedded with the bowlder clay is somewhat harder than that from the sandy deposits at the surface. FORMATIONS BENEATH THE GLACIAL DRIFT. Description. — About 8 miles north of this county the granitic rocks are exposed; in the village of Eden Valley they were struck at a depth of 300 feet, and in several other wells in the northern part of the county at 200 to 300 feet; in Grove City they were probably pene- trated a few hundred feet in a well which went to a depth of nearly 700 feet ; and in the village of Buffalo Lake, south of this county, they were found to lie about 340 feet below the surface. From these data it seems safe to infer that throughout the northern and western parts granite exists within a few hundred feet of the surface and lies immediately beneath the drift or is separated from it by a rela- tively thin series of stratified rocks. On the other hand, at Glencoe, 15 miles southeast of this county, about 1,300 feet of sandstone and other sedimentary rocks have been penetrated, and a depth of 1,640 feet below the surface, or 645 feet below sea level, has been reached without encountering granite. From Grove City and Eden Valley to Glencoe these stratified forma- tions must therefore thicken rapidly, and the granitic surface must descend with relative abruptness. It is thus possible that the south- eastern part of Meeker County is underlain by a thick sedimentary series. The stratigraphic formations between the granite and the drift may be Cretaceous, Paleozoic, or Algonkian. From 6 to 10 miles beyond the northern boundary of the county there are outcrops of beds consisting chiefly of shale, in which Cretaceous fossils have been discovered. a In several wells in the northern and western portions a Kloos, J. H., Am. Jour. Sei., 3d ser., vol. 3, 1872, pp. 17-26. 268 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. of this count)' shales, etc., probably of the same age, have been entered, but there is no evidence that Cretaceous rocks exist in the eastern or southern parts. The great thickness of sediments found at Glencoe comprises chiefly Paleozoic and Algonkian strata, and these may extend into this county. After the Paleozoic formations had been deposited and had been subjected to long erosion the Cretaceous seas probably encroached on the region from the west and spread a thin deposit over the older rocks. At Eden Valley the following section has been reported for a deep well drilled for the railway company: Well section at Eden Valley. [Authority, J. V. McCarthy, driller, Minneapolis.] Thick- ness. Depth. Clay, etc Fine sandstone Black shale Granitic formation. Feet. 200 70 30 60 Feet. 200 270 300 300 From the data at hand it is impossible to determine whether the sandstone and shale in this section should be correlated with the Cretaceous or the Paleozoic. Yield, head, and quality of the water. — At Glencoe the sandstone provides liberal quantities of water, but it has not yet been ascer- tained to what extent this series is developed in Meeker County. In the railway well at Eden Valley, whose section is given above, the supply from the sandstone stratum was tested at 15 gallons a minute; in the northwestern part of the county other wells have been drilled to granite without passing through any water-bearing sandstone. In no locality can flowing wells be obtained by deep drilling. The Paleozoic rocks afford fairly good boiler water, but probably not better than that from the deeper beds of the drift. Compare the analyses in the accompanying table (p. 271) with those given in the report on McLeod County. The granite is not water bearing, except that small supplies are rarely procured from the altered upper portion. WATER SUPPLIES FOR CITIES AND VILLAGES. Litchfield. — Litchfield lies in the midst of an extensive plain under- lain by a deposit of sand and gravel, which at present furnishes the entire water supply. Beneath this deposit lies the bowlder clay of the glacial drift. The public supply is derived from a system of twenty-eight 2-inch driven wells about 42 feet deep, which end in sand, the water rising to a level 20 feet below the surface. Pumping by suction from all these wells combined at the rate of 600 gallons MEEKER COUNTY. 269 a minute for several hours continuously produces no noticeable effect on the level. , About 500 people use the water, and 60,000 gallons is reported to be consumed daily. Fully three-fourths of the inhabitants depend on private wells, nearly all of which are driven to depths of 25 to 45 feet and yield generously. The railway com- pany is also supplied by a shallow well. The water from the sand and gravel near the surface is hard and will produce considerable scale in boilers. This is shown by an analysis of the water from J. T. McNulty's well, which is given in the table. There are some indications that better water could be obtained by drilling deeper. Basset. — The village of Dassel lies in the midst of a morainic area with an irregular surface and numerous small lakes. The following section is reported for the upper 65 feet: Well section at Dassel. Thick- ness. Depth. Feet. Yellow clay 20 Blue clay - - - - > 20 Sand i 10 Blue clay - - - ' 12 "Hardpan' (a few inches thick) \ , Sand and gravel (water) ". J Feet. 20 40 50 62 65 Beds of sand also lie at depths of 120 and 180 feet, the deeper bed furnishing much water. The public supply is taken from a well 8 inches in diameter and ISO feet deep, which is finished with a screen. The water rises to a level 55 feet below the surface, or 1,034 feet above the sea, and pumping has been continued for eighteen hours at the rate of 45 gallons a minute. The water has considerable temporary but little permanent hardness and will not produce much hard scale in boilers. An analysis will be found in the table. Eden Valley. — The valley in which the village of Eden Valley lies is partly filled with alluvial sand and gravel, saturated with water, and most of the wells are driven to a depth of about 30 feet in these deposits. The public supply is obtained from a system of nine 2^-inch wells, one of which is 28 feet and the others 44 feet deep. The water rises to a level about 15 feet below the surface, and the combined system of wells has been tested at 75 gallons a minute. Approximately 5,000 gallons is consumed daily. The railway com- pany has abandoned the deep well the section of which is given above, and at present uses shallow water. According to the anafyses contained in the table below, the deep drift water is better for boiler purposes than that from shallow sources. Grove City. — The village well now in use at Grove City is nearly 700 feet deep. No reliable record was kept, but the drill seems to have passed through several hundred feet of glacial drift, then 270 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. through strata of shale and sandstone, and finally through a con- siderable thickness of partly decomposed granite. The well was at first finished in such a manner that water could enter only from the bottom, when it yielded but 16 gallons a minute. The casing was then cut at the sand and gravel zone found between the depths of 220 and 260 feet, and a 30-foot brass screen was inserted, after which the well was successfully tested at 75 gallons a minute. The water now rises to a level 57 feet below the surface, or 1,150 feet above the sea. About four-fifths of the inhabitants use water from shallow private wells. The analyses given in the table show that the water from the deep zone which supplies the waterworks is not as hard as the shallow water that is tapped by the private wells. FARM WATER SUPPLIES. There are three principal types of farm wells — -driven, bored or dug, and drilled. The driven wells are confined to the level tracts where the sand and gravel are at the surface, and the very shallow and inexpensive wells of this type usually yield generously. Shallow- bored and dug wells still exist in large numbers and are widely dis- tributed, though especially characteristic of the morainic areas. There are also many drilled wells, especially in the eastern and north- ern parts of the county, and these generally afford abundant supplies. They have a wide range in depth, about 100 feet being the most common. Nearly all are 2 inches in diameter and are finished with screens. In the southern part of the county these screens generally become incrusted in the course of several years, but in the northern part it seldom so happens. In the northern part the water from the drift has not much permanent hardness, and this is also true of the water from the lower portion of the drift in the southern part. The suggestion is therefore made that in the latter region there would be an advantage in drilling deeper than is usually done at present, both to get softer water and to diminish the ctifficulty with the screens. This difficulty can also be obviated in great measure by drilling wells of larger diameter. SUMMARY AND ANALYSES. Water-bearing sandstone may be present in the southeastern part of the county at a depth of several hundred feet, but this has not been proved by actual drilling. Where it is present it will yield a fairly good quality of boiler water, but probably not better than the deeper portions of the drift. It will nowhere give rise to flows. The most significant fact to be noted here is that the water from the shallow sources is generally poorer for boiler purposes than that from the deposits at some depth. MOWER COUNTY. 271 Mineral analyses of water in Meeker County. [Analyses in parts per million.] Depth feet. . Diameter of well inches. . Silica (SiOa) Iron (Pe) Iron and aluminum oxides (Fe203+ AI2O 3 ) Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+K) Carbonate radicle (CO3) Bicarbonate radicle (HCO3) Sulphate radicle (SO4) Chlorine (CI) Nitrate radicle (NO3) Total solids Surface deposits. Surface sand and gravel. 44 2; 24 .5 2.4 93 27 20 .0 327 94 11 2.5 439 40 2 25 .2 1.2 115 32 21 .0 293 166 36 .0 550 Upper portion of glacial drift. 60 32 Trace. 4.8 154 32 25 400 183 27 20 C84 .0 Lower portion of glacial drift. 130 2 27 1.2 6.4 88 27 420 14 3 382' .2 2.4 429 15 399 250± 8 28 1 3.2 69 24 21 .0 356 26 2.5 .0 349 1. Village wells at Eden Valley. October 10, 1907. 2. Well of J. T. McNulty at Litchfield. September 21, 1907. 3. Well on West Main street at Grove City. This well belongs to the municipality, but has no connec- tion with the waterworks. September 21, 1907. 4. Well of James McCane, near Eden Valley, on the NW. \ sec. 10, T. 121 N., R. 31 W. October 10, 1907. 5. Village well at Dassel. September 20, 1907. 6. Village well at Grove City. This is the well that supplies the public waterworks. September 21, 1907. The above analyses were made for the United States Geological Survey by H. A. Whittaker, chemist Minnesota state board of health. MOWER COUNTY. By C. W. Hall and M. L. Fuller. SURFACE FEATURES. Mower County is among the highest and flattest of the counties in southeastern Minnesota. Its surface extends for miles with hardly an irregularity to catch the eye. The highest part is a broad, flat swell, which is crossed by the Chicago, Milwaukee and St. Paul Rail- way in the vicinity of Dexter, where the elevation is 1,416 feet above sea level, or 786 feet above the Mississippi at La Crosse. From this vicinity the land declines with a gentle slope to an altitude of 1,300 feet near the eastern boundary, and to about 1,200 feet along Cedar River near the western edge. The valley of the Cedar is the only one of consequence in the county, and its bottom is generally less than 100 feet below the level of the adjacent prairie tract. Other streams flow in shallow depressions or meander about over the prairie, not yet having cut valleys. SURFACE DEPOSITS. The surface deposits include ordinary glacial drift, outwash gravels, and recently deposited alluvium. The whole surface of Mower County, except at one or two points in the stream valleys, is covered by glacial drift, which has a thickness ranging up to 50 ,feet in the valley of Cedar River, from 75 to 100 feet along the eastern margin 272 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. of the county, and from 150 to more than 200 feet in the central por- tion. The drift generally yields sufficient water for domestic and farm purposes. Outwash gravels occur along the course of Cedar River. They are probably not more than 50 feet thick and contain moderate amounts of water. They supply domestic and farm wells at a number of points. The alluvium deposited by the present streams is of minor im- portance in this county, being limited to narrow belts of no great thickness. PALEOZOIC FORMATIONS. The Devonian consists of a lower fine-grained dolomitic limestone and an upper shaly sandstone. The former underlies the greater part of the southern half of the county, except in the valleys of Cedar River and Rose Creek, in which the streams appear to have cut through the limestone. The sandstone, which is known as the " Austin rock," occurs immediately beneath the drift in the central and northwestern portions of the county. Its thickness has nowhere been definitely measured, but probably does not exceed 50 feet. Though not especially porous, this sandstone has yielded good sup- plies at several points, the volume in some places being sufficient for industrial and public supplies. The Maquoketa, Galena, Decorah, and Platteville formations prob- ably have a considerable combined thickness, but they have not been positively recognized in the county. They probably lie below the drift throughout a belt several miles wide in the northeastern part of the county. Beneath the rocks already described no doubt occurs the entire Paleozoic sequence of southeastern Minnesota, older than the Platte- ville limestone. The separate formations are described in connection with the several counties in which they lie at the surface. A sec- tion of the formations at Austin is embodied in the following record of the deepest city well. Compare with this the record of the city well, 260 feet deep, published by the Geological Survey of Minnesota. Section of city well at Austin b Thick- ness. Depth. Glacial drift: Surface soil and loam Sand and gravel Clay and sand Paleozoic formations: Light-colored limestone (arenaceous) Dark-colored limestone "Mud vein " (water-bearing) Dark-colored limestone, etc. (Maquoketa and Galena) Shale, etc. (Galena) White, fine-grained sandstone (St. Peter) Dolomite and sandstone (Shakopee, New Richmond, Oneota). Feet. 5 17 12 4 45 2 340 55 105 125 Feet. 5 22 34 38 83 85 425 480 585 710 a N. H. Winchell, Fourteenth Ann. Rept. Geol. and Nat. Hist. Survey Minnesota, 1885, p. 16. 6 Furnished by Prof. Andrew Nelson. MOWER COUNTY. 273 Throughout the county the St. Peter sandstone will yield large and permanent supplies, as will also the several sandstones at greater depths. UNDERGROUND WATER CONDITIONS. Wells. — The wells of Mower County are of four general classes: The first embraces the shallow wells ending in glacial drift; the second, the drilled weUs which end in the deeper portions of the glacial drift; the third, the shallower rock wells reaching the Devo- nian sandstone in the southern and the St. Peter in the northern parts of the county; and the fourth, the deep rock wells. The shal- lowest wells are generally dug or bored, the water being obtained in sandy or gravelly layers in the drift and, in a few wells, in the Paleo- zoic rocks at a depth of from 10 to 40 feet. Where the drift is thick, it supplies many drilled wells. These average more than 100 feet in depth, and some of the deepest ones exceed 200 feet. Where the drift is thin, the supplies of water which it yields are not satisfactory, and rock wells are relied on, most of them obtaining their supplies from the Devonian sandstone or the sandstone lenses in the Galena and Platteville, though in some places, as at Austin, wells have been sunk to the St. Peter sandstone, from which large supplies of good water are procured. Head of the water. — The head of the water in the shallow drift wells conforms in a general way to the topography. In the southeastern corner of the county there are several flowing wells which belong to the artesian areas of the vicinity of Chester, Iowa. In the deeper wells there is much greater variation in the head relative to the sur- face. At Austin the water from the St. Peter, Platteville, and Galena rises within 10 feet of the surface, or about 1,185 feet above sea level; at Rose Creek, which lies 90 feet higher than Austin, the water from the Devonian sandstone stands 130 feet below the surface, or about 1,165 feet above sea level. WATER SUPPLIES FOR CITIES AND VILLAGES. Austin. — The public supply at Austin is derived from four wells, one 300 feet deep, and three ranging between 600 and 710 feet. There is also a well 175 feet deep which is no longer used. The wells are near to one another and are piped to flow into a cistern 22 feet deep, from which the water is pumped into the mains. The maximum combined daily yield is about 1,000,000 gallons. Nearly one-half of the people use the public supply, and about 500,000 gallons is con- sumed each day. Adams. — The public supply at Adams is drawn from a well 291 feet deep, ending in Devonian rock, and is used by about two-thirds of the people. The rest depend chiefly upon shallow private wells. 60920°— wsp 256—11 18 274 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. The depth to the St. Peter sandstone probably exceeds 500 feet, but ample supplies can be procured from rock formations nearer the surface. Grand Meadow. — The public supply at Grand Meadow is obtained from a well 125 feet deep, which probably ends in Devonian sand- stone. Most of the people depend on private wells. Le Roy. — The village of Le Roy is provided with a public supply drawn from a well 422 feet deep. The log of this well to a depth of 382 feet, is as follows: Section of village well at Le Roy. [Authority, W. G. Banks.] Thick- ness. Depth. Feet. Glacial drift ! 10 Limestone and shale j 1G0 Blue clay 45 Sandstone 60 Limestone and shale I 107 Feet. 10 170 215 275 382 Rose Creek. — The public supply at Rose Creek is derived from a well which ends in what is supposed to be Devonian sandstone at a depth of 175 feet. This well has been tested at the rate of 100 gallons a minute. Most of the people are supplied from private wells. Lyle. — In this village the average thickness of the surface mate- rial scarcely exceeds 35 feet. A layer of sandstone and gravel within the Devonian furnishes most of the water. The public supply is drawn from a well 240 feet deep. Most of the people depend on private wells. SUMMARY AND ANALYSES. In all parts of the county large and permanent supplies can be pro- cured from the St. Peter sandstone at a depth of several hundred feet, and it is probably never necessary to drill to the sandstones that lie still deeper. • For most purposes adequate supplies can be obtained from the glacial drift, Devonian sandstone, or Galena and Platte- ville arenaceous layers, before the St. Peter sandstone is reached. The water from all depths is moderately hard. Judging from analysis 9 in the table below, the water from the St. Peter contains but little mineral matter that will form hard scale in boilers or that can not be removed by heating. MURRAY COUNTY. 275 Mineral analyses of water in Mower County. [Analyses in parts per million.] Surface deposits. 2. 3. 12 30 97 90 32 9.2 8.6 15 306 280 133 55 2.8 16 430 342 Devonian, Galena, and Platteville. St. Peter sand- stone. Depth feet. Calcium (Ca) Magnesium ( Mg) Sodium and potassium (Na+K) Bicarbonate radicle (HCO3) Sulphate radicle (SO4) Chlorine(Cl) Total solids 60 21 3 276 9 2 235 15 56 58 16 190 56 25 311 226 75 24 8.5 302 47 4.1 315 135 62 21 10 296 10 5.2 253 272 127 11 413 243 67 15 18 316 10 .9 245 600 69 24 7.2 314 17 6.1 279 1. Hall's spring at Austin. May, 1901. 2. Chicago, Milwaukee and St. Paul Railway well at Ramsey October, 1892. 3. Chicago, Milwaukee and St. Paul Railway well at Le Roy. November, 1892. 4. Chicago, Milwaukee and St. Paul Railway well at Adams. December, 1892. 5. Chicago, Milwaukee and St. Paul Railway well at Dexter. October, 1892. 6. Former city well at Austin. November, 1891. 7. Old Chicago, Milwaukee and St. Paul Railway well at Austin. June, 1901. 8. New Chicago, Milwaukee and St. Paul Railway well at Austin. August, 1901. 9. City well at Austin. June, 1901. The above analyses were reported by G.N. Prentiss, chemist Chicago, Milwaukee and St. Paul Railway Company. MURRAY COUNTY. By O. E. Meinzer. SURFACE FEATURES. The surface of Murray County consists of a gently undulating, poorly drained prairie which slopes gradually from about 1,800 feet above sea level in the western part to less than 1,300 feet in the north- eastern. Two parallel moraines extend over this prairie with a northeast-northwest trend, the outer crossing the southwestern and the inner the northeastern part of the county. They have an irregu- lar, hummocky topography and rise distinctly above the surrounding country. The streams of the county have few tributaries, and the extensive interstream areas are covered with a network of swamps, ponds, and lakes, the largest of the latter being Lake Shetek, in the north-central part. Beaver Creek rises in the outer moraine and flows eastward to the inner, where it joins the outlet of Lake Shetek to form Des Moines River, which thence flows southeastward along the outer margin of the inner moraine. The area beyond the outer moraine is drained southwestward by Chanarambie Creek, which has cut a gorgelike valley ; the region inside of the inner moraine is drained in the opposite direction by Plum Creek, which likewise occupies a deep narrow valley. SURFACE DEPOSITS. Description. — So far as is known, the glacial drift covers the older rocks at all points in the county, and throughout most of the region it is thick. A number of wells have been reported which end in drift at depths of more than 250 feet, and several over 400 feet deep also 276 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. appear, from the sections furnished by the driller, to be entirely in the drift. No record has been received of any well in the western half of the county that has reached the underlying formations, but such wells are numerous in the northeastern and southeastern corners where the drift is relatively thin. See the list of rock wells given below. The sections shown in Plate XIII are typical of the drift in this county and are especially interesting in showing the existence of the interbedded layers of yellow cla}^. Yield of water. — The structure of the drift is to a great degree chaotic, and no water-bearing layer can be traced for a great distance. Thus the sections of two wells a mile apart may be quite different. Yet in nearly every locality one or more pervious beds exist which reserve ample stores of water. The 8-inch village well at Slay ton, 205 feet deep, is pumped at the rate of 45 gallons a minute, and the 6-inch village well at Currie, 120 feet deep, has been tested for thirty- six hours continuously at the rate of 60 gallons a minute. Head of the water. — Owing to differences in altitude there are im- portant differences in the depth at which the water stands below the surface. In the two high morainic belts it remains at considerable depths, especially in the deeper wells, but on the lower prairie land which comprises most of the county it usually rises nearly to the surface from all horizons. There are several small areas of flowing wells, which may be enumerated as follows (PI. IV) : 1. The Badger Lake area. This is a small district surrounding Badger Lake, 2\ miles east of Iona. About six flowing wells, ranging between 85 and 110 feet in depth, have been drilled in this basin. The lowest has a good pressure, but reduces the head of those on higher ground. 2. The Lime Creek area. There is a flowing well in the NE. \ sec. 34, T. 106 N., R. 41 W., and one in the SE. \ sec. 24, T. 106 N., R. 41 W. Others can be obtained along this stretch of Lime Creek. 3. The Lake Wilson area. Three flowing wells have been drilled in the village of Lake Wilson. These are about 85 feet deep, have a head of several feet, and flow from 5 to 10 gallons a minute each. 4. The Beaver Creek area. There is a flowing well 133 feet deep in the SE. \ sec. 4, T. 106 N., R. 42 W., and one 35 feet deep about 1 mile north of Lake Wilson. It seems probable that others with slight pressure could be procured along this portion of Beaver Creek. There is also a flowing well 80 feet deep 2 miles north and 2 miles east of Lake Wilson, and one of the same depth a half mile farther east. There is little doubt that other depressed localities would afford wells in which the water would rise slightly above the surface. In a low area bordering a high morainic tract the water from the seams of sand beneath the blue bowlder clay is likely to rise approximately to the surficial ground-water level, and if a small portion of such an GEOLOGIC SECTIONS IN SOUTHERN MURRAY AND NORTHERN NOBLES COUNTIES By O. E. M Willmont —Village well. Authority, G. J. Savidgc, driller. Wayne, Nebr. Xi.rilm.-.l "i :-'l"\-l"ii Well ! null im.il I ■.' 1,11 1, v. ,0 3 ) Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+ K) Carbonate radicle (C0 3 ) Bicarbonate radicle (HCO3) Sulphate radicle (SO<) Chlorine (CI ) Nitrate radicle (N0 3 ) Total solids 47 120 31 1.3 5.4 68 3S 57 .0 349 145 5 .5 529 252 58 36 395' 350 150 45 1,112 60 144 33 1,217 93 9 194 196 71 75 70 82 401 567 514 485 45 1.5 1,164 78 12 36 4.6 5.3 179 60 24 429' 374 3 907' 348 8 29 3 3.2 435 159 114 .0 38.6 1,583 6 Trace. 2,540 1. Village well at Adrian. July 30, 1907. 2. Well at the residence of Doctor Williams, at Wilmont. August 1, 1907. 3. Railway well at Bigelow. November 28, 1900. 4. City wells at Worthington. November 27, 1900. 5. Two city wells at Worthington. July 31 , 1907. 6. Village well at Wilmont. August 1, 1907. Analyses 1, 2, 5, and 6 were made for the United States Geological Survey by H. A. Wh'ttaker, chemist Minnesota state board of health. Analyses 3 and 4 were furnished by G. M. Davidson, chemist Chicago, St. Paul, Minneapolis and Omaha Railway Company. OLMSTED COUNTY. By C. W. Hall and M. L. Fuller. SURFACE FEATURES. The greater part of the surface of Olmsted County belongs to the plateau which extends over the entire region. In the southern half it stands at an elevation of about 1,300 feet above sea level, but to the north, where softer rocks are exposed, it subsides to an altitude of 1,000 to 1,200 feet. In this region the upland surface is not con- tinuous, the rather even crests of the ridges between the streams being its only representative in places. In certain localities the •gen- eral plateau level is broken by mounds and hills of the Galena, Decorah, and Platteville formations or by the sinks of the limestone surface. The principal valle3 7 s are those of the Zumbro, in the west- ern part of the county, and of the tributaries of the Root and other streams in the southeast and east. The valleys are only 200 to 300 feet deep, and, though marked by steep walls or bluffs in places, do not OLMSTED COUNTY. 291 commonly have the canyon-like character exhibited by the streams nearer the Mississippi. In the limestone areas the streams some- times flow in underground channels for considerable distances. About three-fourths of the area of Olmsted County is drained due north by the South Fork of the Zumbro. The erosion which has been effected by the Zumbro has caused a rapid encroachment of its tributaries from the south upon the basins of streams draining the region covered by Olmsted and Dodge counties, thus affording a clear example of stream piracy. SURFACE DEPOSITS. The surface deposits include alluvium, loess, and glacial drift. The alluvium consists of irregularly stratified gravels and sands deposited along the valleys of the present streams, especially Zumbro and Root rivers. Its thickness varies, but probably rarely exceeds 50 feet, though locally it may be considerably greater. It contains moderate amounts of water and affords supplies to shallow wells sufficient for domestic and farm purposes. The narrow shelves or terraces which occur in some localities along the borders of the valleys contain little water at depths above the level of the adjacent streams. The loess deposits are too thin to be important as sources of sup- ply, but they serve to collect the rain falling on the upland surfaces and to feed it to the underlying rock formations. The glacial drift in Olmsted County is a heterogeneous mass of clay, pebbles, and bowlders. There seem to be two sheets, separated locally by beds of peat. Near the southwestern corner of the county the drift is 75 to 100 feet thick, but it becomes thinner eastward until in the eastern part of the county it is present only in scattered patches. In the southwestern area the drift includes a number of sandy or gravelly layers capable of holding considerable amounts of water, which is yielded to farm and domestic wells throughout the uplands. Where the drift is in patches it is rarely of importance as a source of water. PALEOZOIC FORMATIONS. The Maquoketa shale, as represented in this county, consists of about 15 feet of argillaceous shale, sandy shale, and impure lime- stone. It is present only in a small area in the southwestern, part of the county, where it yields small supplies to domestic and farm wells of moderate depth. The Galena limestone, Decorah shale, and Platteville limestone have an aggregate thickness of about 200 feet. They are found beneath the higher uplands, where the limestones locally yield water supplies of moderate volume. The Decorah shale is not water 292 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. bearing but serves to collect the water from the overlying limestones, bringing it to the surface as springs, which are locally important for farm purposes. The St. Peter sandstone is about 110 feet thick and outcrops along the Root" River valley in the southeastern part of the county and along the Zumbro River valley and its tributaries in the northern and northwestern parts of the county. Generally it has a flat grass or timber-covered surface, which is locally broken by mounds of sandstone preserved by a hard cap of the overlying Platteville lime- stone. It dips southwestward and underlies the greater portion of the county. It usually affords abundant water for domestic and farm purposes and even for small industrial and public supplies. The Shakopee dolomite, which is about 35 feet thick, outcrops in the cliffs along the principal rivers and underlies extensive areas of uplands near the northern border of the county. It affords a very compact widespread base for the overlying St. Peter, but yields water enough only for the most restricted requirements. Many springs emerge from the top of this formation where it outcrops. The New Richmond sandstone is exposed in the upper portion of the Zumbro and Root River valleys. It underlies a large part of the Shakopee area in the northern part of the county and will furnish supplementary supplies of importance to wells of moderate depth. The Oneota dolomite occurs beneath the alluvium in the bottom of the Zumbro Valley and its tributaries in the northern part of the county and in the Root River valley near the county line on the south. It also underlies the uplands throughout the county and is about 200 feet or less in thickness. It contains very little water but gives rise to springs along the valleys mentioned. The Jordan sandstone is about 120 feet thick. The formation underlies the entire county and is generally saturated with water, yielding good supplies to deep wells, though on the uplands the water must be lifted several hundred feet by pumps. The St. Lawrence formation consists of 200 feet or more of calca- reous shales and sandstones. It carries some water, but the amount is less than in the overlying Jordan or in the underlying Dresbach. The Dresbach sandstone, which is here about 50 feet thick, underlies the St. Lawrence and is a strong water-bearing bed, but not stronger than the Jordan, 250 feet above it. Where large volumes are needed, however, for industrial or public purposes, the Dresbach sandstone will furnish supplementary supplies that will doubtless prove important. Below the Dresbach sandstone are about 150 feet of grayish or greenish shales, and below these is more than 200 feet of porous sandstone containing abundant water. As is true of the Dresbach, however, owing to the abundance of water in the overlying Jordan, OLMSTED COUNTY. 293 there is no advantage in sinking wells to this lower sandstone except for supplementary supplies. The red clastic series, consisting of red shale, sandstone, and quartzite, underlies the sandstone just described and is in turn underlain by the granite. Neither of these, however, affords water supplies and neither has been reached by borings in this county. UNDERGROUND WATER CONDITIONS. Wells. — Formerly wells 10 to 35 feet deep were common through- out the county, but the supplies were found deficient in dry seasons and the water more or less liable to pollution. For these reasons drilled wells entering the rock have been largely substituted, though many shallow wells are still in use. Most of the drilled wells pene- trate the rock only a short distance, but at Rochester a well has been sunk to the Dresbach sandstone, this being the only well of notable depth in the county. Head of the water. — The head of water, relative to the surface, varies considerably, owing to the topographic irregularities. In the northern portion of the county there are a few flowing wells. WATER SUPPLIES FOR CITIES AND VILLAGES. Rochester. — The public supply of Rochester is obtained from a series of wells sunk into the alluvium near the mouth of Bear Creek. These wells derive their head from the alluvium of the creek valley south of the city. The water is used by about one-half of the people. Several years ago a deep well was drilled at the State Hospital for the Insane near Rochester. As the hospital grounds are con- siderably above the city, the drilling was begun in Galena or Platte- ville limestone. The section is interesting because it represents nearly the entire Paleozoic development of southeastern Minnesota: Well section at Rochester. Thick- ness. Depth. Soil, loess, drift, and broken limestone St. Peter sandstone Shakopee dolomite, New Richmond sandstone, and Oneota dolomite. Jordan sandstone Limestone and sandstone (St. Lawrence and Dresbach?) Shale Sandstone Feet. 75 100 150 175 300 80 80 Feet. 75 175 325 500 800 880 960 Stewartville. — A well 63 feet deep has furnished the public supply at Stewartville up to the present, but a new well was being drilled in 1908. About 8,000 gallons of water is consumed daily. Eyota. — A compressed air system of waterworks has recently been installed by the village of Eyota. The supply comes from a well 10 inches in diameter and 203 feet deep. 294 UNDERGROUND WATERS OE SOUTHERN MINNESOTA. SUMMARY AND ANALYSES. The sandstones that underlie this county yield ample and perma- nent supplies. Usually an adequate amount of water can be ol>t ained from the St. Peter at a moderato depth, but where it can not there need be no hesitation in drilling to the Jordan, which lies about 200 feet deeper and has proved an excellent water-bearing formation wherever it has been encountered. No Hows can be obtained on the uplands, to what over depth drilling may be carried. Mineral analyses of water in Olmsted County. [Analyses in parts per million.] Dresbaoh sand- stone. Depth feet Silica (SiOs) Calcium (Cal Magnesium ( Mg) Sodium and potassium ( Na+ K) Bicarbonate radicle (HCOs) Sulphate radicle (SO«) Chlorine (CD Total solids Alluvium and gla- cial drift. St. Peter sand- stone. .Ionian sand- stone. 1. 2. 3. 4. 32 32 140 150 13 14 12 9. 8 80 77 65 73 22 15 17 31 11 7.0 2. 6 15 352 300 279 368 ll 15 2. 7 • >•> 9. 6 4.7 4 11 320 290 241 343 13 79 is 5.9 288 (> 5 290 1 . City wells at Rochester. July, 1S90. 2. City wells at. Rochester. October, 1900. 3. Chicago and Northwestern Railway well at Ryota. May, 1S89. 4. Chicago and Northwestern Railway well at Rochester. 'May, 1S89. 5. Rochester well at the Hospital for the Insane at Rochester*. October, 1900. Analyses 1, 2, 3, and 4 were furnished by (5. M. Davidson, chemist, Chicago and Northwestern Railway Company. Analysis 5 was made for the United States ecological Survey by ll. s. Spaulding. PIPESTONE COUNTY. By O. E. Meinzer. SURFACE FEATURES. Most of Pipestone County consists of a gently undulating prairie, but near the northeastern corner it is crossed by an irregular morainal ridge that rises above the surrounding plain and reaches an altitude of more than 1,900 feet above sea level. This ridge forms the boundary between the swampy, lake-covered region to the northeast and the better-drained area virtually free of lakes or swamps to the southwest. It also forms the divide between the Mississippi and Missouri basins, giving rise to Redwood and Des Moines rivers on its northeastern flank and to Flandreau Creek and Rock River on its southwestern. Rock River flows southward through a rather wide valley near the eastern margin of the county, and just before it leaves this county it is joined by Chanarambie Creek coming from the east. Flandreau, Pipestone, and Split Rock creeks drain the western half of the county, all flowing southwestward. PIPESTONE COUNTY. 295 SURFACE DEPOSITS. Description. — The upland surface is in general covered with the bowlder clay and sandy deposits of the glacial drift, but in the valley of Rock River and in some of the smaller valleys are found extensive alluvial deposits, for the most part also of glacial origin. The drift varies greatly in thickness. On the morainal ridge in the north- eastern corner it is several hundred feet deep and the underlying formations have seldom if ever been reached in drilling, but in many localities in the central, southern, and western parts it is absent or very thin. A line drawn diagonally from the northwestern to the southeastern corner will roughly form the boundary between the deep and the shallow drift. Plate II shows the thickness of the drift in as much detail as possible. Yield of water. — In the northeastern part of the county and in other localities in which the drift is deep, it will usually supply plenty of water for all purposes, but where its depth is not great the yield is frequently inadequate. In the areas where it is thinnest the drift furnishes only a small percentage of the water consumed, but the proportion increases with the thickness and is virtually 100 per cent where the drift is as much as 300 feet thick. The drift is so chaotic in its structure that chance must determine whether, in a given locality, with a given thickness of drift, a satisfactory supply can be procured without drilling into rock, but the chances increase with the thickness in a geometric progression. Head of the water. — The only flowing wells reported in this county are one 19 feet deep, just north of Edgerton, and one 45 feet deep, situated southwest of Pipestone on the farm of Anna M. Kothe, NW. \ sec- 22, T. 106 N., R. 46 W. The level to which the water rises varies considerably and is farthest below the surface in the deepest wells on the morainal ridge. Where the quartzite projects above the general level of a region the head of water in the surrounding drift is higher than elsewhere, and many springs occur. Quality of the water. — All the water from the surface deposits is more or less highly mineralized, the drift water generally being harder and richer in dissolved minerals than the water from the alluvium. CRETACEOUS SYSTEM. Throughout most of southwestern Minnesota a series of shales and sandstones of Cretaceous age lies below the drift, and it is not improb- able that this series extends into the northern and eastern parts of Pipestone County, but it has probably never been reached in drilling. SIOUX QUARTZITE. Description. — Beneath the less indurated deposits lies the Sioux quartzite, or "red rock," which is referred to the Algonkian system. 296 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Although on the whole this rock is remarkably uniform in color, hardness, and composition, consisting essentially of a thoroughly indurated red quartzite of great thickness, yet it is not entirely uniform. Its color ranges through various shades of red, from light pink to dark purple. The hardness also varies greatly, and in a few places strata of incoherent sand are encountered. Neither is the composition altogether uniform, for interbedded with the quartzite there are occasional thin layers of pipestone, of which one outcrops in the famous Indian quarry near the city of Pipestone and others are reported by drillers. The rock is plainly stratified and commonly cross-bedded and ripple marked, has a gentle but varying dip, and is broken up by a system of joints. The quartzite surface consists for the most part of relatively level plateaus cut by canyons and abruptly terminated by escarpments. The following is a representative list of wells which enter the quartz- ite, together with the depth to the rock and the distance it was penetrated : Table of typical wells in the Sioux quartzite of Pipestone County. [Given on the authority of drillers and other persons.] Owner and location. Depth to rock. Distance drilled in rock. Total depth of well. C M. Flagg, NW. $ sec. 3G, T. 107 N., R. 40 W W. L. Tallman, SE. } sec. 25, T. 107 N., R. 40 W. . M. Ackerman, NE. J sec. IS, T. 107 N., R. 45 W... J. R. Atwood, NW. i sec. 17, T. 107 N., R. 45 W— J. Iluemoeller, NW. i sec. 32, T. 107 N., R. 45 W. . A. Johnson, SW. Jsec.31, T. 107N., R. 45 W W. F. Boock, SW. i sec. 27, T. 106 N., R. 46 W . . . J. R. Hubbard, S. J sec. 8, T. 106 N., R. 46 W J. Johannsen, SE. J see. 32, T. 106 N., R. 46 W W. S. McDonald, NE. J sec. 22, T. 106 N., R. 46 W I. B. Smith, SE. i sec. 29, T. 106 N., R. 46 W P. V. Whitehead, SE. } sec. 18, T. 106 N., R. 46 W Pipestone city well, No. 1 Pipestone city well, No. 2 R. O.Curl, NW. isec. 19, T. 106 N., R. 45 W A. McQuaid, NE. i sec. 6, T. 106 N.,R. 45 W F. Buck, NE. i sec. 7, T. 105 N., R. 46 W L. Erickson, SE. { sec. 22, T. 105 N., R. 46 W S. Grummer, SW. J sec. 19, T. 105 N., R. 46 W H. F. Hanson, NW. \ sec. 30, T. 105 N., R. 46 W. . H. O. Hogsted, SE. \ sec. 34, T. 105 N., R. 46 W... A. Mitchell, SW.J sec. 27, T. 105 N., R. 46 W G. Nelson, NW. \ see. 34, T. 105 N., R. 46 W Taylor & Burg, SW. \ sec. 18, T. 105 N., R. 46 W .. J. W. Wehrman, N. 4 sec. 29, T. 105 N., R. 46 W... L. W. Alexander, NW. { sec. 5, T. 105 N., R. 45 W J. O. Alexander, SW. \ sec. 5, T. 105 N., R. 45 W.. Myers & Miller, E. isec. 4, T. 105 N., R. 45 W J. D. Quinn, NW. f sec. 6, T. 105 N., R. 45 W Feet. 30 60 140 100 SO 30 50 300 42 102 22 SO 30 70 10 SI 35 17 4 20 97 70 100(?) 80(?) 37 60 Feet. 270 110 80 70 90 130 72 258 27 96 6 173 323 SO 140 50 200 44 S5 146 210 38 31 100(?) 70(?) 500 100 Feet. 300 170 220 170 170 160 122 300 300 129 118 86 200 350 160 170 120 210 125 35 102 150 230 135 101 200 150 537 160 Yield of water. — Formerly the quartzite was not considered a water-bearing formation, but the great dearth of water in some locali- ties forced the experiment of deep drilling into it. Almost everywhere it was found to yield some water, and it is now depended on as a reliable source of supply. The body of the quartzite is massive and firmly PIPESTONE COUNTY. 29*7 cemented; but the water percolates through the joints or "crevices" by which the rock is broken and also through certain portions in which the pore space is not entirely filled by cementation. Below the ground-water level all open spaces are saturated and will contribute some water to a well brought into communication with them. Although the amount furnished by any single "crevice" or pervious layer is usually small the effect is cumulative, and as drilling is con- tinued the well becomes connected with more and more of these water-bearing elements. The depth to which it is necessary to sink in order to get an adequate supply is to a large extent determined by chance, depending on the course of the well in passing through com- pact and unbroken rock or in encountering many "crevices" or pervious beds. Nevertheless, the yield of rock wells is usually very small as compared with that of wells in more porous formations. It is cus- tomary for drillers to guarantee only 100 gallons an hour in farm wells, though the actual yield is often much greater. In nearly all wells the supply is found to be permanent and sure. The two city wells at Pipestone, which are 6 and 8 inches in diameter and 200 and 350 feet deep, together deliver 140 gallons a minute for an indefinite period when an air-tight lift is employed. It seems that tolerably large yields can nearly always be procured if the wells are sunk to a sufficient depth. Head of the water. — The level at which the water stands in the wells depends largely on the topography. It is generally less than 100 feet but commonly more than 50 feet below the surface. Quality of the water. — The quartzite itself contributes very little mineral matter to the water, and hence where the rain enters it directly the water remains soft. But in most localities the rock is covered by a layer of drift through which the water must first perco- late, thereby being rendered more or less highly mineralized. The analyses given in the accompanying table (p. 300) are representative of the quartzite waters of this county. WATER SUPPLIES FOE, CITIES AND VILLAGES. Pipestone. — The Sioux quartzite is at or near the surface in the eastern part of the city of Pipestone and at no great depth in the western part. To the north it forms a low west-facing ledge, over which Pipestone Creek leaps in a small cataract. The public supply is derived from two wells in the center of the city, about 20 feet apart. One of these is 200 and the other 350 feet deep. The upper 27 feet consist of clay, below which there is quartzite, the casing extend ng only to the rock. The water rises to a level 96 feet below the surface or 1,630 feet above the sea. By 298 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. means of an air lift the wells have been made to yield 127 gallons a minute for ten hours continuously, and this is reported to have lowered the water level about 10 feet. More recently they have been tested at 140 gallons. The water is remarkably clear and, as the analyses show, is only moderately hard. It is used by about 2,300 people, or perhaps 90 per cent of the total population, the average daily consumption amounting to approximately 60,000 gal- lons. In most of the city the quartzite is so near the surface that no water can be obtained except by expensive drilling, but in the western part, where the distance to rock is greater, there are some shallow bo.red wells. Jasper. — The Sioux quartzite, which outcrops in the eastern part of the village of Jasper as a west-facing ledge, gives rise to springs, one of which near the center of the settlement furnishes the public supply. This spring yields somewhat more than 50 gallons a minute and is reported not to be greatly affected by drought. Its water is relatively soft, as is shown by the analysis given in the table (p. 300), and is used by about 200 people, an average of 10,000 gallons being consumed daily. Perhaps two-thirds of the inhabitants depend on private wells. In the western part of the village most of these end in deposits of sand and clay at very shallow depths, the ground- water table being at or near the surface; but in the eastern part there are several rock wells. Edgerton. — The village of Edgerton is located between Rock River and Chanarambie Creek, on a wide low terrace built of alluvial sand, gravel, and clay, with which the valley is partly filled. The public supply is taken from a well 16 feet in diameter, sunk to a depth of 24 feet in the alluvial deposits. The level at which the water stands in this well varies somewhat with the season. In August, 1907, it stood about 13 feet below the surface; at that time pumping at the rate of 265 gallons a minute for two hours continuously would lower the water to 2 1 feet below the surface, and the same rate of pumping continued for four hours would empty the well. In dry years the ground-water table is lower and the yield is probably much less. The water is only moderately hard, as is shown by the analysis given in the table (p. 300). The private wells, which supply water for approximately 75 per cent of the people, are dug or bored to a depth of about 15 or 20 feet and end in alluvium. In a part of the village sand and gravel beds are absent and consequently there are no wells. No deep drilling has been done, but there are several abandoned holes between 100 and 200 feet in depth. Ruthton. — The village of Ruthton is situated near the headwaters of Redwood River, where the altitude is relatively high and the glacial drift is deep. The following is the approximate section of the 6-inch well that supplies the public waterworks : PIPESTONE COUNTY. 299 Well section at Ruthton. Thick- ness. Depth. Yellow clay Blue clay Sand and gravel. Blue clay Sand Feet. 25 70 10 139 16 Feet. 25 95 105 244. 260 In this well the water rises to a level about 60 feet below the surface or 1,680 feet above the sea. After it was drilled (in 1905) it was finished with a 16-foot screen and was then pumped at the rate of 35 gallons a minute for ten hours continuously without noticeable effect. The water, which is hard, is utilized very little at present except for fire protection. All the people use water from private wells, most of which are sunk to depths of only 20 or 30 feet and afford small supplies. The creamery and mill are provided with drilled wells about 105 feet deep and there are several other wells of this type. FARM WATER SUPPLIES. The farm supplies are drawn from two distinct sources, the deposits of drift and alluvium and the quartzite or "red rock." The wells which terminate in the drift and alluvium are drilled, bored, dug, or driven; those which penetrate the quartzite are of course all of the drilled type and are generally 6 inches in diameter. In the region including Pipestone, Jasper, and Trosky, which was described above as the area of shallow drift, a large proportion of the farms are supplied from rock wells ranging from about 60 to 300 feet in depth. Formerly almost the only source of water consisted of the shallow wells that ended in the drift above the quartzite, but these proved so unreliable that they have to a great extent been abandoned for rock wells. Drilling in quartzite at first presented serious difficul- ties, but those who have made a specialty of this kind of work have overcome these difficulties to such a degree that failures are now very rare. No one need hesitate to have a well sunk into the rock if he can afford the cost,, but it is important to employ an experi- enced rock driller, as otherwise there is liable to be trouble. Prob- lems involved in drilling in quartzite are discussed under the heading "Problems relating to wells" (pp. 87-88). SUMMARY AND ANALYSES. Pipestone County is divisible into two distinct ground-water provinces — (1) the area of thin drift in which the rock is near the surface and (2) the area of thick drift where the rock is deeply buried. The portions of the county included in each are shown on 300 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Plates II and III. Jasper, Trosky, Ihlen, Pipestone, and Altona lie in the first area; Ruthton, Holland, Woodstock, and Edgerton are in the second. In the former it is often necessary to drill into rock, which, if penetrated to a depth of several hundred feet, will usually afford enough water not only for farm purposes, but also for ordinary industrial and public supplies. In the second area large and per- manent stores of water are usually contained in the sand and gravel seams of the drift and in the alluvial deposits of the Rock River valley. The composition varies, but the water from the quartzite, as well as that from the alluvium, is on an average softer than the glacial drift water. In neither area are flowing wells to be expected. Mineral analyses of 'water in Pipestone. County. [Analyses in parts per million.] Surface deposits (glacial drift, etc.). Sioux quartzite. Depth feet. . Diameter of well inches. . Silica (SiO-j) Iron (Fe) Aluminum ( Al) Iron and aluminum oxides (Fe^Os+AliOs) Calcium (Ca) Magnesium (Mgl Sodium and potassium (Na+K) Carbonate radicle (CO3) Bicarbonate radicle (HCO3) Sulphate radicle (S0 4 ) Chlorine (CD Nitrate radicle (N0 3 ) Total solids 24 192 .0 210 19 2.5 10 230 (?) f 200 i 350 6 and S 17 .12 3.2 307 6 4 124 21 15 346* 67 35 35 504 444 23 4.2 4S 19 16 .0 261 16 11 3.6 269 160 68 33 620* 41 351 89 31 442 28 3S 3ir' 59 36 4 425 1.2 104 49 110 372 368 1. Village well at Edgerton. August 1, 1907. 2. Railway well at Hatfield. October 15, 1888. 3. Spring which furnishes the public supply at Jasper. August 6, 1907. 4. Well near Jasper, on the farm of L. Erickson, SE. J sec. 22, T. 105 N., R. 46 W. August 6, 1907. 5. "City well" at Pipestone. June 24, 1SS9. 6. Mixture of water from the two city wells at Pipestone. August 2, 1907. 7. AVell at Pipestone. October 25, 1901. Analyses 1, 3, 4, and 6 were made for the United States Geological Survey by H. A. "Whit taker, chemist, Minnesota state board of health. Analyses 2 and 5 were furnished by G. N." Prentiss, chemist, Chicago, Milwaukee and St. Paul Railway Company. Analysis 7 was furnished by G. M. Davidson, chemist. Chicago, St. Paul, Minneapolis and Omaha Railway Company. RAMSEY COUNTY. By C. W. Hall. SURFACE FEATURES. The southern two-thirds of the surface of Ramsey County is covered with rough moraines, among which lie many lakes. In the northern third the surface is flat or undulating, but poorly drained, broad swampy tracts and numerous lakes occupying the shallow depressions. There is little variation in the altitude of the upland surface. The highest points are in the morainal hills along the eastern border and at points in the southwestern part of the county, the altitudes here being EAMSEY COUNTY. 301 somewhat more than 1 ,000 feet above sea level. The Mississippi flows in a deep channel, the width varying from a few hundred yards above Fort Snelling to a mile or more below that point and to several miles below St. Paul. The river is bordered by a terrace cut into the rock at a height of 100 feet or more above the water. This terrace is nearly continuous across the south edge of the county, but varies in width from a mile or more near the mouth of the Minnesota and near St. Paul to about one-eighth of a mile at the southeastern corner of the county. The tributary streams are numerous, but generally meander over the undulating surface in indefinite valleys, except near the Mississippi, where they have cut somewhat deeper channels. SURFACE DEPOSITS. Alluvium occurs chiefly along the Mississippi Valley below St. Paul, but some of it borders the river as far as the mouth of the Minnesota, and small amounts occur along the smaller streams. Its greatest thickness is not known, but is probably 50 to 100 feet or more. It is saturated with water and will afford moderate supplies, but not enough for industrial purposes. Terrace gravels occur along the Mississippi at various levels, but are most prominent on the 100-foot terrace described above. Near the river the water has generally been drained from them, but back from the stream considerable supplies may be obtained. The glacial drift varies from indistinctly laminated clay to a hetero- geneous mixture of clay, sand, and gravel. Beneath the clay, incor- porated between successive beds of it, or spread over the surface, are many thick layers of sand and gravel. The clay generally has a red- dish tinge, due to material brought in by the Lake Superior lobe of the last glacial invasion. The total thickness of the drift is consid- erable, in many localities being more than 100 feet. The sandy parts and interbedded gravel beds are saturated with water, which is given up freely to wells penetrating them. One of the features of special geologic interest, as well as of impor- tance with regard to underground water, is the buried preglacial stream valley entering St. Paul from the northeast and joining the Mississippi. To the north it has been penetrated at Lake Vadnais, where a well was sunk 230 feet before striking rock, though the rock on either side occurs at only about half this depth. Similar relations exist in St. Paul, well records on either side showing the surface rock to be Galena limestone, whereas within the channel the first rock penetrated is the Shakopee dolomite or the Oneota dolomite, which is stratigraphically about 200 feet lower. The well of the St. Paul Harvester Works, near Phalen Creek, a short distance south of the outlet of Lake Phalen, found 235 feet of drift in the channel, this depth of drift being about 150 feet greater than the average at either 302 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. side. The channel bottom is at least 100 feet below the present level of the Mississippi and represents the bed of an old stream entering the Mississippi when the latter flowed at a much lower level than at present. PALEOZOIC FORMATIONS. The Galena, Decorah, and Platte ville formations are here represented by a blue limy shale, with alternating thin limestone layers, having a maximum thickness, according to the record of the well at the reform school, of at least 132 feet. The beds are seen in the south bluffs of the Mississippi, between Mendota and St. Paul, and they underlie the high residence district known as St. Anthony Hill. The lower beds are calcareous and partly crystalline and are economically important as a source of building stone. The jointed condition gives rise, along the transition bed, to springs which otherwise would issue much higher. The beds, as a whole, however, are not to be regarded as a source of water supply. The St. Peter sandstone is about 150 feet thick, and about 40 feet above the bottom has a shale parting. It outcrops along the bluffs of the Mississippi and underlies the formations previously described throughout the county. Near the northeastern and northwestern corners it probably lies immediately below the glacial drift. It con- tains abundant supplies of water. Even near the river water is obtained, often under considerable pressure, from the bed beneath the shale parting, this portion not being drained, because it lies below the river level, except in the southern part of the county. In the city of St. Paul, however, where the wells are close together, they interfere, to a certain extent, with one another, and the supplies are correspondingly reduced. The Shakopee dolomite lies deep below the general surface of the county and forms the rock walls at the bottom of the Mississippi gorge from the neighborhood of the St. Paul levee to the south limit of the county. It carries relatively little water and is not to be regarded as a source of supply. The New Richmond sandstone is only a few feet thick and is not continuous. Where present it contains a moderate supply of water, though much less than the thicker sandstones. The Oneota dolomite has a considerable thickness, but, like the Shakopee, it carries relatively small amounts of water. The Jordan sandstone is between 70 and 125 feet in thickness. Although merging into shale at the base, it is an excellent water- bearing formation and yields large supplies to a considerable num- ber of wells in St. Paul and the vicinity. Where wells are crowded together, however, as they are in this county, the supply is con- siderably depleted and the head of the water noticeably lowered. The St. Lawrence formation consists of blue limestone, alternating with blue or green shales and a few sandstone layers, and has a total EAMSEY COUNTY. 303 thickness of 150 to 200 feet. Some water is present, especially in its sandy layers, but the amounts are small in comparison with those yielded by sandstones above and below. The Dresbach sandstone and underlying shales aggregate several hundred feet in thickness. The sandstone carries rather large amounts of water and is the source of supply in a number of deep wells. In general, the amounts to be obtained are no larger than in the Jordan, but where the Jordan has been depleted by the multi- plication of wells the Dresbach constitutes an important supple- mentary source. The red clastic, series of shale and sandstone comprises the lowest rocks entered in Ramsey County. It has considerable thickness, but the amount of water which it yields is too small to be of economic value. UNDERGROUND WATER CONDITIONS. Head of the water. — The northern part of Ramsey County abounds in lakes, which lie between 880 and 930 feet above sea level and mark the surficial ground-water table of the drift deposits. The deeper wells show a lower head than those ending in the glacial drift. Nev- ertheless, in the lower part of the city of St. Paul and along the entire stretch of the valley of the Mississippi bordering this county, the surface is so much below the upland level that flowing wells are obtained. Within the city of St. Paul the boundary of the flowing area extends into the business district as far as Seventh street, between Minnesota street and the border of Daytons Bluff, and corresponds roughly to the 740-foot contour. The head was at one time higher than this and is probably steadily falling, so that the statement of altitude is merely an approximation. In the northern part of the county the water from deep sources will rise somewhat higher above sea level than in the valley of the Mississippi, and though it will not come to the surface the pressure is everywhere adequate to bring it to a height sufficient for economic uses. Quality of the water. — In Plate XIY will be found a large number of analyses of waters from all the principal zones. It will be noted that the waters from the glacial drift and from the St. Peter, Jordan, and Dresbach sandstones do not differ greatly from one another. Each group is moderately mineralized, the principal dissolved constitu- ents being the calcium, magnesium, and bicarbonates, which produce a father soft scale in boilers, but render the water hard. These con- stituents can be removed in large part by heating, so that the water is left softer and better for boiler use. An important fact developed by the assembling of the analyses is that the water beneath St. Paul is somewhat softer than that from the same formations beneath Minneapolis. (Compare Pis. X and XIV.) 304 UNDEEGEOUND WATEES OF SOUTHEEN MINNESOTA. ST. PAUL PUBLIC SUPPLY. The public supply for the city of St. Paul is obtained from several sources. Most of it is derived from glacial lakes north of the city, but a part comes from wells at Lake Vadnais and Centerville Lake. At Lake Vadnais there are 12 wells. The following is the log of one of the deepest, which is 10 inches in diameter and was sunk in 1904: Section of deep well at Lake Vadnais. [Authority, Twenty-third Rept. Board of Water Commissioners, St. Paul, 1905.] Thick- ness. Depth. Feet. 20 230 297 324 351 434 620 059 Clay and sand Sand Limestone Hard sandstone Hard limestone Fine white sandstone Very fine white sandstone. Coarse white sandstone . . . Feet. 20 210 67 27 27 83 186 When this station was first installed it had a capacity of 5,000,000 gallons, the wells all being connected and working together, but a test made in 1904 showed the total capacity at that time to be only 3,516,000 gallons, a decrease of about 63 per cent for the deep wells and of about 37 per cent for the shallow wells. The Centerville group consists of 10 deep wells 12 inches in diam- eter and 302 to 523 feet in depth, all of which enter the Jordan sandstone, and 18 shallow wells 8 inches in diameter and 51 to 76 feet, averaging 62J feet deep. In the report on Anoka County the section of one of the deep wells is given (p. 130.) In 1907 the average daily consumption of public water was 10,781,044 gallons. SUMMAEY. The four principal water zones are (1) the glacial drift, (2) the St. Peter sandstone, (3) the Jordan sandstone, and (4) the Dresbach and basal Cambrian sandstones. Their stratigraphic position and depth beneath the surface, as well as the mineral character oi the water from each, are shown in Plate XIV. The water from the deeper sandstones is under sufficient pressure to rise considerably above the level of Mississippi River. REDWOOD COUNTY. By O. E. Meinzer. SUEFACE FEATUEES. Most of Redwood County consists of a flat plain that rises imper- ceptibly southwestward. This plain is intermediate in altitude Silica (SiOj) Oxides of iron and aluminum (Fe,( Calcium (Ca) sium (Mg) n and potassium (Na-t-K) Bicarbonate radicle (HCO,) Sulphate radicle (SOJ Chlorine (CI) Total solids PUBLIC SUPPLY GLACIAL DRIFT 269. 11.2 5.1 NEW RICHMOND DRESBACH, ETC St. Peter sandstone Shakopee dolomite New Richmond sandstone Oneota dolomite" Jordan sandstone, St. Lawrence formation Dresbach sandstone Shales and sandstones Red clastic series City datum 694,7 ESI m 940 945 660- 'pi E3! i?° «B . Public supply taken at City a 1 County Hospital. June, 1900. Dearborn labo- 1901, by G. M. l)aviil.-(»ti,rli t -m^t, I'hica^o, St. - Bear March, 1890 Dearboi ANALYSES OF ST. PAUL WATERS ARRANGED AVERAGED ACCORDING TO ROCK FORMATIONS. Lutheran Seminary well. December, 1895. Dearborn Inbm Minnesota Hiirvivti-r Company well. 22. St. Paul Furnitui ■ell. April, 19(11). Dearborn l:il. i-rut-.. / Furniture ( |miiv v.vil Seplcnil-.r . IWHi. Dearborn laboratory. . I';iul l-'ouieln- C 1 .i.i|.iiiiv w<:\\. .Inn'.-, 1M*. Pear-bon, laboratory, aienvorks well ;-.( North SI Paul. October, 1893. Portland Apartments well. June, 1896. Dearborn laboratory. Vin-.mme brother-; well. I i.-.i'inl-. r, ]«"'>. i>earb..Ni laboratory. i Ap'irhiK'iit- well. I'Vl.ruiirv, l.-'»;. Iv.u-i. blu.iM icklniT Ciriiranv well Uav,' l'JOii. Dearborn laboraU M.Mil .illewell. , 1M17. Et Dea ohner,au:ilv.-t. lanl of Health. tb orator) . . ^v. ill iV; I ■-. w.-ll .il I--- February, 1905. Minnesota d'st. Paul Railway well. November, 1891. well. October, 1899 Dearborn laboratory, Railway well, ill, Si Paul REDWOOD COUNTY. 305 between the valley of Minnesota River on the northeast and the Coteau des Prairies on the southwest. With reference to the valley, which is 150 to 200 feet deep, it constitutes a plateau, but in relation to the coteau, which lies 500 feet higher, it is a lowland tract. The ascent to the coteau begins m the southwestern extremity of the county, where the upward grade is greatly augmented. Redwood and Cottonwood rivers flow eastward across the county, occupying rather shallow valleys until as they approach the Minne- sota, into which they discharge, they descend into deep and pictur- esque gorges. This is especially true of Redwood River, which cas- cades over a granite ledge at Redwood Falls. Until the principal streams have cut their valleys down to accord with the Minnesota most of the county will have insufficient relief for an adequate drain- age. Near the southwestern corner, however, where the descent from the coteau is relatively steep, many ravines have been cut, some of which extend down to the ground-water level and have per- manent streams fed by springs. This is why nearly all the affluents of Cottonwood River come from the south. SURFACE DEPOSITS. Description. — The surface deposits consist of glacial drift and re- cent alluvium. The drift occurs everywhere except in small areas in the Minnesota Valley, in the valley of Redwood River below the falls, and in some of the western townships where older formations are exposed. Over most of the eastern, central, and southwestern parts of the county it is between 100 and 200 feet thick and locally it reaches a still greater thickness. In the northwestern part it is generally thinner, being less than 50 feet thick throughout a large portion of the following six townships: Vail (T. Ill N., R. 37 W.), Granite Rock (T. Ill N., R. 38 W.), Westline (T. Ill N., R. 39 W.), Sheridan (T. 112 X., R. 37 W.), Vesta (T. 112 N., R. 38 W.), and Underwood (T. 112 N., R. 39 W.). Yield of water. — Where the drift has considerable thickness it generally includes deposits of sand and gravel that will produce water supplies adequate for all ordinary purposes, but where it is less than 100 feet thick it may not contain a reliable water-bearing bed. In the northwestern part of the county, especially in the town- ships mentioned above, the drift is not an entirely satisfactory source of supply, although in a large portion of these townships it is the only available source. Head of the water. — The water from the glacial drift is generally under considerable pressure but is not known to rise above the sur- face. The flowing wells in the southwest are supposed to be supplied from the Cretaceous rocks, but no record could be obtained of most of them, and it is possible that some end in the drift. Many springs 60920°— wsp 256—11 20 306 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. issue from the sides of the Minnesota Valley, and these have lowered the head of the water beneath the adjacent uplands. Quality of the water. — The analyses given in the accompanying table (p. 313) reveal a wide range in the mineral composition of the water. The Walnut Grove analysis (No. 5) represents a very poor variety of water that is not uncommon in the drift of the region; the Redwood Falls analyses (Nos. 1 and 2) are perhaps more typical of the average water from this source. CRETACEOUS SYSTEM. Description. — Throughout most of this county Cretaceous strata lie beneath the. drift. In the southwest they have a thickness of several hundred feet, but they thin out toward the east and north. They occur everywhere in the southern tier of townships and almost everywhere in the tier next north. They are also found adjacent to Lyon County nearly or quite to the north boundary but are absent in the vicinity of Vesta and Seaforth and in much of the northwestern part of the county. Small and irregularly distributed areas containing thin deposits of this age are concealed below the drift in the northeastern part, but the accurate mapping of these patches can not be accomplished until many more well sections are available than at present. The following specific data bear on the occurrence of the Cretaceous in this county: (1) At Tracy, 1 mile west of the county line, a series of Cretaceous shales and sandstones about 450 feet thick has been penetrated. (2) At Walnut Grove there is a considerable thickness of the same series but no definite section is available. (3) Near Pell Creek, along the road from Revere to Lamberton, Cretaceous clay and sandstone come to the surface, and in the SE. \ sec. 11, T. 109 N., R. 38 W., shale was struck at a depth of 110 feet. (4) At Lamberton an 80-foot stratum of shale was reached at a little more than 200 feet below the surface. (5) In Sanborn a sandstone and shale series was entered at a depth of 217 feet and was penetrated for 53 feet. (6) A few miles east of Sanborn, along Cottonwood River, Cretaceous outcrops are found. (It seems probable that the deposits of Cretaceous clay, sandstone, etc., exposed in the outcrops lie above the thicker shale beds encountered in drilling and are not generally differentiated from the drift in well sections.) (7) Near Cottonwood River, south of Milroy, a number of deep wells have been sunk and shale and sandstone about 400 feet in thickness have been penetrated by the drill. (8) In the village of Milroy shale is encountered at a depth of only 35 feet, and it seems to have been penetrated for about 230 feet. (9) In the southwestern corner of Underwood Township (T. 112 N., R. 39 W.), a 75-foot stratum of blue shale, underlain by white sand, was reached 45 feet below KEDWOOD COUNTY. 307 the surface. (10) One mile west of Lucan, on the farm of Patrick Curtin, NE. f sec. 20, T. Ill N., R. 38 W., shale was found at a depth of 70 feet. (11) At Clements the same material was struck at 115 feet and was penetrated only a short distance. (12) In the valley of Redwood River below the falls and in the Minnesota Valley between Redwood Falls and Morton outcrops of thin Cretaceous strata are found. a (13) In the northern part of the county shale has been encountered in drilling. There are two phases of the Cretaceous in this region. One phase, which consists of rapidly alternating and imperfectly assorted strata of clay, sand, sandstone, etc., indicates by the rude stratifica- tion the cross-bedding of the sandstone, the red oxidized character of much of the clay, the lignite beds, the fossil leaves, and other features that the conditions of deposition were nonmarine or littoral. The other phase consists for the most part of a thoroughly assorted series of soft shale and sandstone, the shale greatly predominating and having a characteristic gray-blue color. It attains a maximum thickness in this State of at least 500 feet, and was evidently laid down in a large and quiet body of water, where thorough assortment and stratification were possible. It is to be correlated with the Cretaceous in South Dakota and other Western States. These two phases are described in the reports on Brown and Lyon counties where they are respectively best developed. Their exact relation to each other has not been determined. The series in the western and southern parts of Redwood County belongs to the Lyon County phase, and the rocks in the northeastern part belong with those in Brown County. Yield of water. — Where the Cretaceous is several hundred feet thick it will yield moderately large quantities of water, as is illustrated by the 6-inch city well at Tracy, which is pumped at the rate of 50 gallons a minute, and by the 6-inch village well at Walnut Grove, which is pumped at the rate of 35 gallons a minute. In general it may be said that in the vicinity of Milroy and thence southward and southeastward to Walnut Grove and Revere the Cretaceous can be depended on for adequate supplies, but that northeast of Lamber- ton and Lucan it is generally absent or devoid of any good water- bearing stratum, though in a few localities it will furnish some water. Head of the water. — The Cretaceous area of flowing wells, the extent of which is shown in Plate IV, projects from Lyon County into the southwestern part of this county. The southwestern margin of the area enters the county about 4 miles north of the southern boundary and thence passes to Walnut Grove and approximately to the Cottonwood county line. It enters the county between the 1,200-foot and 1,300-foot contours and gradually descends until it a Upham, Warren, Final Rept. Geol. and Nat. Hist. Survey Minnesota, vol. 1, 1882, pp. 570, 572, and 578. 308 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. nearly coincides with the latter. The northeastern margin enters the county about 3 miles north of Cottonwood River and for some distance runs roughly parallel to that stream but eventually crosses it and passes southward to Revere, where there are several flowing wells. The northeastern margin is determined to a great degree by the thinning out of the Cretaceous and the consequent failure of the deep artesian beds; this condition is more fully discussed in the report on Lyon County. However, throughout the flowing area the head is not great and the natural flow never exceeds a few gallons a minute. Moreover, immediately outside of this area there are wells in which the water rises nearly to the surface. Thus in the Cretaceous wells at Walnut Grove it fails only by a few feet to reach the top, and in the similar wells at Milroy it comes within 15 to 20 feet of the top. Quality of the water. — The Cretaceous contains both hard and soft water zones. At Milroy soft water is reported at a depth of about 100 feet and hard water at about 260 feet. South of that village a number of wells 300 to 500 feet deep yield hard water, and in the vicinity of Walnut Grove and Revere the principal zones to a depth of at least 300 feet supply soft water. (See the analyses given in the accompanying table.) The Sanborn analyses may represent a mixture of drift and Cretaceous waters. SIOUX QUARTZITE. The Sioux quartzite, which attains a relatively great thickness farther south, projects into the southern part of Redwood County in the form of a wedge between the Cretaceous and the granite. At Lamberton it is reported to have a thickness of several hundred feet. It is probably of no economic value in this county as a source of water. ARCHEAN ROCKS. ARCHEAN PROPER. The Archean consists of granite and gneiss, which constitute the basal rocks. Throughout the northern and eastern parts of the County it is everywhere relatively near the surface. In the vicinity of Seaforth three outcrops are known, and there are several others in Yellow Medicine County, within a mile or two of the boundary line; it is frequently encountered in drilling in this region. Moreover, in the Minnesota Valley and in the Redwood Valley both above and below the falls it is exposed. In the southern part of the county, however, the granitic surface descends and within a short distance is many hundreds of feet below the surface. Thus at Tracy, Lyon County, it occurs at a depth of a little more than 600 feet, or not quite 800 feet above sea level, and at Lamberton it was reported about 600 feet below the surface, or only 550 feet above the sea. EEDWOOD COUNTY. 309 Farther south it lies at so great a depth that it is very seldom reached by the drill. At Blue Earth, Faribault County, and at Sioux City, Iowa, it was struck at a level 135 feet below the sea, a and at Lemars, Iowa, at 215 feet above the sea. a The upper part is generally much altered and passes gradually into the unchanged granite. This decomposed mantle is best exposed in the gorge of Redwood River below the falls, where it has been described by Prof. N. H. Winchell, 6 but the same kind of material is encountered in many of the wells of the region. Drillers do not always differentiate clearly between the Cretaceous beds and the rotted granite, though it is of great practical importance that the distinction be made. Brilliant colors (red, yellow, green, white, etc.), flakes of mica or steatite, which give the drillings a silvery appearance not possessed by the Cretaceous shale ("soapstone"), transparent and angular grains of quartz, which give a gritty character never found in the shale, and hard quartzose ("glassy") layers alternating with soft material, all indicate that the granitic residuum has been reached. WHITE CLAY. Material from an outcrop near Morton, in Renville County, is described as follows by N. H. Winchell: A substance was met here for the first time which was afterward seen at a number of places. Its origin seems to be dependent upon the granite. Its association is so close that it seems to be the result of a change in the granite itself. It lies first under the drift, or under the Cretaceous rocks, where they overlie the granite, and passes by slow changes into the granite. It has some of the characters of steatite and some of those of kaolin . In some places it seems to be a true kaolin . It is known by the people as "Castile soap." It cuts like soap, has a blue color when fresh or kept wet, but a laded and yellowish ash color when weathered, and when long and perfectly weathered is white and glistening. The boys cut it into the shapes of pipes and various toys. It appears like the pipestone, though less heavy and less hard, and has a very different color. It is said to harden by heating. This substance, which may, at least provi- sionally, be denominated a kaolin, seems to be the result of the action of water on the underlying granite. Since it prevails in the Cretaceous areas, and is always present, so far as known, whenever the Cretaceous deposits have preserved it from disruption by the glacier period, it may be attributed to the action of the Cretaceous ocean. In some places it is gritty, and in others it may be completely pulverized in the fingers. A great abundance of this material exists in the banks of the Birch Coolie, within a short distance of its mouth. Since the above statements were made, this clay, which is com- monly whiter and less ferruginous than the sample described, has been found in scores of deep wells, and thus much additional evidence has been obtained as to its distribution and character. All this new evidence, however, corroborates Winchell's statements that it overlies the granite, into which it passes by slow changes, and that it prevails a Norton, W. H., Geol. Survey Iowa, vol. 6, 1896, pp. 227-229, 232, 233, and 235. b Final Rept. Geol. and Nat. Hist. Survey Minnesota, vol. 1, 1882, p. 571. c Second Ann. Rept. Geol. and Nat. Hist. Survey Minnesota, 1873, p. 163. 310 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. in the Cretaceous areas and is generally present wherever the Cre- taceous deposits have preserved it. A conception of its wide distri- bution can be gained by referring to the reports of the counties in which the Archean lies beneath the Cretaceous. In this county it is exposed in the valleys of Minnesota and Redwood rivers and has frequently been reached in drilling, especially in the vicinity of Vesta and Seaforth, where it is near the surface. In the gorge of Redwood River decomposed granite occurs which has a matrix of white clay very similar to the white clay under discussion, except that it is less compact. In this matrix are imbed- ded the angular, transparent grains of quartz which existed in the mother rock. It is the thoroughly weathered and leached granitic residuum left in its original position. On the south side of the wagon road from Redwood Falls to Morton, where the descent is made from the upland into the valley, there is a typical exposure of the white clay. It is here evidently of sedimentary origin, as it is free from quartz grains and lies above a stratified layer of grit. The outcrop appears nearly white. Two samples, one from each of the above- described exposures, were analyzed for the United States Geological Survey by Prof. F. F. Grout, of the University of Minnesota, with the results shown below. In preparing sample 1 the white matrix was washed out from the quartz grains, so that the latter do not enter into the analysis. No. 3, which gives the composition of kaolin, is inserted for comparison. Composition of granitic residuum, white clay, and kaolin. Silica (SiOa) Alumina (AI2O3) a H2O on ignition. . . 1. Gra- nitic re- siduum. 45.92 39.84 14.12 2. White clay. 43.86 41.82 14.65 3. Kaolin. 46.5 39.5 14.0 a With the alumina of No. 1 is associated a trace of iron, and with that of No. 2 a little iron and about 0.3 per cent of titanium oxide (Ti02). The analyses show that the composition of the white clay is similar to that of the granitic residuum, and that both are similar to kaolin. It will be seen, however, that the white clay and, to a less extent, the residuum are a little higher in alumina and a little lower in silica than kaolin, as a result, according to Professor Grout, of the presence of small amounts of beauxite. The white color is due to the fact that the iron has nearly all been leached out. Well sections and outcrops show that in some places the white clay contains imbedded grains of quartz and is clearly residual, as in the exposure in the Redwood gorge; that in others it is entirely free from grit but includes interbedded strata of sand, as in the Tracy well, the exposure near Morton, etc.; and that in still others quartz grains are present in the lower part and absent in the upper, as in REDWOOD COUNTY. 311 many wells in Renville County. In brief, the white clay consists in part of granitic residuum, and in part of sedimentary deposits derived therefrom. a Essentially this conclusion has been reached by Warren Upham and others. b It is important that drillers should distinguish this clay both from the ordinary Cretaceous shale and from the ordinary decomposed granite, because its significance as to water supplies is somewhat different from that of either. It does not usually yield water, but the interbedded layers of grit, where they occur, may furnish adequate supplies. A number of good wells draw from this source, but there are also many instances on record where drilling into the clay has resulted in failure. The white clay is always a warning that the drill is approaching granite. WATER SUPPLIES FOR CITIES AND VILLAGES. Redwood Falls. — The city of Redwood Falls is located at the point where Redwood River cascades over the granite ledges into a steep and rugged gorge. The granite is everywhere relatively near the surface. The public supply is derived from two springs about 1 mile south of the city, on the east bank of the river. They issue from a bed of gravel immediately above the granite, and in dry years their yield is not great. The water is hard and will form scale in boilers, as the analysis in the table shows (p. 313) . Approximately 1,000 people are supplied, and the average daily consumption amounts to about 30,000 gallons. The railway company takes water from a shallow well and also uses the public supply, and at the 'mill water from the river is used. The private wells are shallow and unsatisfactory. Lamberton. — The following is the approximate section for the local- ity of Lamberton as revealed in the deep drilling done for the village. Well section at Lamberton. - Thick- ness. Depth. Yellow clay Sand (thin) Blue clay Quicksand Blue clay White material (Cretaceous) . Blue shale (Cretaceous) Red quartzite (Algonkian).. Granite (Archean). Feet. 35 135 3 50± 2 80 300 ± Feet. 35 170 173 223 ± 225± 305± 605± o The information was derived from several sources, and there is some question as to the correctness of the lower portion of the section. The public supply is derived from an 8-inch well, which draws its water through an open end from a gravel bed 19 inches thick 64 feet below the surface. The water rises to a level 30 feet below the a The decomposition of an igneous rock which contains no quartz might produce a white clay free from grit, but this can not be the entire explanation in southwestern Minnesota. & Upham, Warren, The glacial Lake Agassiz: Mon. U. S. Geol. Survey, vol. 25, 1895, pp. 88-90. Also Hall, C M., and Willard, D. E., Casselton-Fargo folio (No. 117), Geol. Atlas U. S., U. S. Geol. Suivey, 1905, p. 2. 312 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. surface. When the well was completed (1901) it was tested for thirty- six hours continuously at the rate of 60 gallons a minute, and at pres- ent it is pumped at about 35 gallons a minute. The water is hard. Approximately 10,000 gallons is consumed daily. Private wells, which furnish the supply for most of the inhabitants, have an average depth of about 40 feet and their yield is closely dependent on the amount of precipitation. Walnut Grove. — The public supply for the village of Walnut Grove is obtained from a 6-inch well 312 feet deep, in which the water rises within 12 feet of the surface, or 1,216 feet above sea level. The well was tested at the rate of 37 gallons a minute for eight hours continu- ously. The water is soft but rich in sodium and potassium. Approxi- mately 3,000 gallons is consumed daily, and about 300 people, nearly three-fourths of the total population, are supplied. The railway company uses a soft-water well which is a few feet deeper than the village well. Three analyses of deep water will be found in the table. Sanborn. — The following section is reported from Sanborn village: Well section at Sanborn. [Authority, C. S. Hall, resident engineer Chicago and Northwestern Railway Company, Sanborn.] Blue clay, etc Sandstone (Cretaceous) . Hard shale (Cretaceous) . Sandstone (Cretaceous) . Thick- ness. Feet. 217 13 20 20 Depth. Feet. 21J 230 250 . 270 FARM WATER SUPPLIES. Drilled wells are most numerous in the flowing area and adjacent parts, that is, in the southwestern portion of the county, where the Cretaceous is a sure source of supply. They have an advantage over the shallower- bored wells in that they can be sunk to beds which in most of this area will yield flows of soft water. Flowing wells, those that end in sandstone and those that are 4 inches or more in diameter, are generally finished with open ends, but others must be provided with screens to keep out the sand. Where the water is truly soft the screens will give no trouble, but where it is hard they become incrusted in a few years by the precipitation of calcium carbonate and other mineral matter. In the area northeast of a line drawn through Lamberton and Lucan (including by far the greater part of Redwood County) bored and dug wells greatly predominate. As the depth to the impervious formations in this area averages probably not more than 200 feet and is locally much less, it is necessary to procure water relatively near the surface; and as larger supplies can be developed from weak zones by means of bored or dug wells than by means of the ordinary drilled wells there is reason for preferring the former type. REDWOOD COUNTY. 313 SUMMARY AND ANALYSES. In the area which lies southwest of a line drawn through Revere and Milroy wells yielding moderate supplies can be obtained at depths ranging from 100 to 500 feet. In a large part of this region the water will flow and much of it is soft (PL IV) . In the remaining portion of the county supplies can for the most part be procured only in the upper 200 or 300 feet, no flows are to be expected, and the water is usually hard. Every effort should here be made to finish wells in the deposits of sand and gravel interbedded with the yellow and blue bowlder clays near the surface. Any one of the following kinds of material may be found immediately below the bowlder clay: (1) Blue shale or "soapstone," (2) white clay, (3) decomposed granite, or (4) unaltered granite. If blue shale is encountered, drilling should be continued, as a water-bearing stratum may yet be found; if the white clay is reached the chances of obtaining water are poorer but there is still some reason for hope; if decomposed granite is entered, the chances are still poorer; and when the granite becomes hard drilling should invariably be stopped. It is important to understand the difference between the blue shale, the white clay, and the decomposed granite. There is no good reason for abandon- ing a drill hole when blue shale is struck, but this is frequently done. Mineral analyses of water in Redwood County. [Analyses in parts per million.] Surface deposits (glacial drift, etc.). 3. 4. 5. 6. (?) Cretaceous 11. 12. Depth feet. Diameter of well inches . Silica (SiOa) Iron (Fe) Iron and aluminum oxides (Fe203 +AI2O3) Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+ K) . Carbonate radicle (CO3) Bicarbonate radicle (HCO3) Sulphate radicle (SO4) Chlorine (CI) Nitrate radicle (NO3) Total solids 275 8 26 312 C 12 3.8 322 f2and I 11 325 7 199 66 26 542' 361 7 1.4 158 50 26 511 207 355 222 100 51 196 49 156 543 187 12 370 39 2.5 1,371 1,683 13 470 180 1.3 520 594 19 383 672 8.4 202 660 25 1,296 1,173 17 12 423 268 709 23 1,345' 2.6 1 57 32 12 7 508 457 371 701 912 450 29 40 1,816 1,339 1. Springs which furnish the principal part of the public supply at Redwood Falls. They are located about 1 mile south of the city and a short distance south of the pumping station, in a ravine on the east side of Redwood River. August 30, 1907. 2. Mixture from all the springs which contribute to the public supply at Redwood Falls. November 2, 1893. 3. Well at Vesta. November 27, 1899. 4. Well at Vesta. September 30, 1899. 5. Former railway well at Walnut Grove. February, 1S90. 6. Railway well at Wabasso. January 24, 1902. 7. Well at Sanborn. September 15, 1899. 8. Railway well at Sanborn. December 2, 1899. 9. Flowing well at Revere. January 26, 1899. 10. Village well at Walnut Grove. August 14, 1907. 11. Well at Walnut Grove, owned by the municipality. July 31, 1895. 12. Railway well at Walnut Grove. April 13, 1891. Analyses 1 and 10 were made for the United States Geological Survey by H. A. Whittaker, chemist Minnesota state board of health; the others were furnished by G. M. Davidson, chemist Chicago and Northwestern Railway Company. 314 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. RENVILLE COUNTY. By O. E. Meinzer. SURFACE FEATURES. The surface of Renville County constitutes for the most part a very gently undulating drift plain covered with a plexus of lakes, ponds, and swamps. The monotony of this plain is interrupted only along the southwestern margin, where Minnesota River flows through a valley 1 to 3 miles wide and 175 to 200 feet deep, and where many short, rugged tributary gorges dissect the level uplands. Much the greater part of the county still retains the gentle prairie topography inherited from the Pleistocene epoch, and is quite unmodified by postglacial erosion. SURFACE DEPOSITS. Description. — The glacial drift is found everywhere except in parts of the Minnesota Valley and its tributaries, where underlying formations are exposed. Owing to irregularities in the surface on which it rests its thickness varies somewhat, but in general increases from the Minnesota Valley eastward and northward, attaining a maximum of more than 400 feet, and having an average for the county of perhaps 250 feet. The following table shows the thickness of the drift and the altitude of the surface upon which it rests in the different localities of the county : Thickness and altitude of drift in Renville County. Locality. Thick- ness of drift. Altitude of surface on which drift rests. Feet. 264 297 280 438 340 122 202 Feet. 790 770 800 635 725 850 Franklin 900 840 Yield of water. — The beds of sand and gravel, which occur at different depths, constitute the water-bearing members of the drift. The supplies from the shallow beds are generally meager and are readily affected by drought, but the yield of the deeper zones is generous and permanent. In many places at or near the base of the drift there is a thick stratum of sand and gravel (PL XV) that will furnish large quantities of water. The 6-inch village well at Renville, which is 236 feet deep, has been tested at the rate of 50 gallons a minute for eight hours continuously; the 6-inch village BENVILLE COUNTY. 315 well at Olivia, which is 320 feet deep, has been tested at 60 gallons a minute for twenty-four hours continuously; the 8-inch village well at Bird Island, which is supplied from about 200 feet below the surface, has been tested at 100 gallons a minute for several hours continuously; the 10-inch railway well at the same place, which also derives its water from a depth of about 200 feet, has been tested at 105 gallons a minute for forty-eight hours continuously; and the new 8-inch village well at Hector, which is 400 feet deep, has been tested at 60 gallons a minute for twelve hours continuously. In the southern part of the county, where the drift is not as thick as elsewhere, the underlying formations are sometimes penetrated before a satisfactory supply is obtained. Head of the water. — Throughout most of the county the water rises nearly to the surface, but no flowing wells have been reported. In the vicinity of the Minnesota Valley the head is lower than else- where, because of the water lost through the numerous large springs in the valley. The following table shows the height to which the water rises in the various village wells: Head of the water in Renville County. Locality. Depth to top of water. Head above sea level. Feet. 50 14 30 12 10 50 80 Feet. 1,005 1,065 1,050 1,060 1,055 970 960 Quality of the water. — Throughout the northeastern part of the county the water from the deep beds of the drift Is lower in total mineralization, total hardness, and permanent hardness than that from the shallow sources. This is shown by the accompanying table of analyses. In the southern and western parts of the county, where the drift has only a moderate thickness, the difference between the shallow and deep waters is less marked. The deep-drift water differs both from the shallow-drift water and from the Cretaceous water which exists west of this county. In its content of calcium and magnesium it is intermediate between the two — the shallow-drift water containing large amounts, the Cretaceous water small amounts, and the deep-drift water moderate amounts of these elements. In its content of sodium and potassium the deep-drift water approximates rather closely to the shallow- drift water, both containing moderate quantities of these elements, whereas the Cretaceous water contains large quantities. In its content of sulphates it differs sharply from the other two in that it is 316 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. low in this constituent, whereas they are very high. These differ- ences seem to indicate that the deep water in this county is not derived entirely from the overlying drift nor from the Cretaceous to the west, nor yet from a mingling of the waters from these two sources. An interesting phenomenon noticed in the northern part of the county is the presence of inflammable gas which is brought up in small quantities with the water from a number of the deeper wells. CRETACEOUS AND ARCIIEAN ROCKS. DESCRIPTION. At various points along the valley of the Minnesota are found out- crops of stratified rocks consisting of blue, black, green, and white shales, and of marl, limestone, coal, sand, sandstone, etc. The section exposed is everywhere thin and changes within short distances from one kind of material to another. In some places Cretaceous fossils have been found in these deposits and there is little doubt that they are all Cretaceous in age. The outcrops that have been described in this county can be summed up as follows: 1. In sec 10, T. 112 N., R. 34 W., on the north side of Minnesota River, up the valley of a small creek, are outcrops, described by N. H. Winchell, a of concretionary marl or limy earth of a white color, which he refers to the Cretaceous. 2. Warren Upham b described exposures of Cretaceous clay or shale along Fort Creek, in sec. 31, T. 112 N., R. 32 W. At one place these contain a thin layer of limestone and at another a seam of clayey lignite. He also described an exposure near the foot of the bluff of the Minnesota Valley, in the NE. { sec. 34, T. 112 N., R. 33 W., which consists of gray Cretaceous shale visible to a thickness of 7 feet. 3. C. W. Hall c described an exposure of white sandstone along the wagon road in the same section, and also in the gorge of Birch Coulee at the border of sees. 32 and 33, T. 113 N., R. 34 W., and in sec. 28, T. 113 N., R. 34 W. This sandstone is exposed for 12 or 15 feet. Beneath the Cretaceous rocks is a white or nearly white noncal- careous clay which consists largely of kaolin. In some places it is entirely free from grit, in others it contains embedded grains of quartz, and in still others it is free from grit at the top but contains embedded quartz grains at the bottom. This clay was described by N. H. Winchell, d and a quotation from his description appears in o Second Aon. Rept. Geol. and Nat. Hist. Survey Minnesota, 1S73, p. 187. & Final Rept. Geol. and Nat. Hist. Survey Minnesota, vol. 2, 1SS5, p. 197. c Bull. U. S. Geol. Survey No. 157, 1899, pp. 42 and 43. d Second Ann. Rept. Geol. and Nat. Hist. Survey Minnesota, 1S73, p. 163. RENVILLE COUNTY. 317 the report on Redwood County (p. 309). It has been encountered in many wells in Renville County and in other parts of southwestern Minnesota where granite is reached in drilling, and without doubt owes its origin to the decomposition of the granitic rocks on which it rests. Where it is thin and contains embedded grains of quartz it is probably the undisturbed granitic residuum, but where it has a con- siderable thickness, is free from quartz grains, and contains inter- bedded layers of grit it has evidently been handled by water and is a sedimentary rather than a residual deposit. If this sedimentation took place at the time when the Cretaceous seas invaded the region, as would seem probable, it is a sort of basal formation belonging to the Cretaceous. Evidently it is not always possible, especially in well sections, to locate the precise boundary between the granitic residuum and the Cretaceous. In the maps and sections the white clay is included with the granitic residuum except where it is evidently Cretaceous. Though this method is somewhat arbitrary it represents the facts as accurately as is feasible. Beneath the white clay there is generally decomposed granite, which plainly shows its origin and which gradually gives place downward to the firm, unaltered rock. The Cretaceous rocks are nowhere thick and are absent in some parts of the county; the white clay is found chiefly in the southern part. In some places the Cretaceous rocks, the white clay, and the decomposed granite have all been swept away by the invading ice sheets, and the glacial drift rests immediately upon hard granitic rock. Plate XV gives a detailed section across the northern part of Ren- ville County along the line of the Chicago, Milwaukee and St. Paid Railway. In the east (Hector and Buffalo Lake) the glacial drift seems to rest directly upon the granite, but in the west (Renville, Olivia, and Bird Island) a certain amount of shale and decomposed granite forms the transition between the drift and the unaltered granite. It is not everywhere certain at what point the boundary should be drawn between the Cretaceous and the granitic residuum. The following sections of wells are given to illustrate the character of the formations in the southern part of the county: ° Section at Fairfax (mill tvell). Yellow bowlder clay Blue bowlder clay Sand Blue bowlder clay White, putty-like material free of grit White, putty-like material containing grit (water). Decomposed granite (water) Granitic rock. Thick- ness. Feet. 20 165 1 16 36 Depth. Feet. 20 1S5 1S6 202 238 o Principal authorities, John Ford, driller, Franklin, and B. Henderson, Fairfax, 318 UNDEBGBOUND WATEES OF SOUTHEEN MINNESOTA. Well section at Franklin. Thick- ness. Yellow bowlder clay Blue bowlder clay. . Sand and gravel White clay. Granite. Feet. 110 12 Well section at Morton (Catholic church). Thick- ness. Coarse gravel White clay. . Sand (water) White clay. . Sandstone . . . Feet. 40 75 3 27 Section of well 1 mile north of Morton, on the farm of John Eder. Yellow bowlder clay Blue bowlder clay White clay Sand and gravel (hard water) Section of well 2h miles north of Morton, on the farm of Peter Kavney. Thick- ness. Bowlder clay ' Hardpan"' Soft, sticky, blue-gray clay without grit "Coal" Sand (water). White clay. Section of well 4 miles north of Morton, on the farm of John Jones. Yellow bowlder clay Blue bowlder clay . . White clay Sand (water). Thick- ness. Feet. 124 6 RENVILLE COUNTY. 319 Section of well 4 miles north of Franklin, on the farm of John Drury. Thick- ness. Depth. Bowlder clay, etc White clay Decomposed granite (water). Feet. 130 168 Feet. 130 The following table shows the approximate depth to the granitic surface and its altitude above sea level in the various localities of the county: Depth and altitude of granitic surface in Renville County. Depth to granitic rock. Altitude of granitic surface. Granite Falls (Yellow Medicine County) . Renville Olivia Bird Island Hector Buffalo Lake Morton Franklin (bottom of white clay) Fairfax (bottom of white clay) Feet. (a) 325 345 315 438 340 (a) 150 (?) 230 900 730 730 730 635 725 850 860 810 a At surface. YIELD OF WATER. In the northern part of the county attempts to obtain water in the formations beneath the drift have generally failed, but in the southern part a number of wells have been reported which derive their supplies from layers of sand or sandstone encountered after the Cretaceous deposits or the white clay have been entered. This is true of nearly all the wells whose sections are given above. The mill well at Fairfax, which derives its water from grit and decomposed granite below a layer of the white material, received a rather severe test. The fol- lowing statement was made by one of the drillers in tins county : Beneath the clay (glacial drift) there is a white formation, in general from 30 to 50 feet thick, beneath which there is rotten granite and then hard red granite. The white material is at first soft and putty-like but changes into a harder formation con- taining grit. This gritty white material and the decomposed granite usually contain a good supply of water. QUALITY OF THE WATER. The water from beneath the white clay is of various mineral char- acter, much of it being very hard but some being similar to the deeper drift water. No. 15 in the table (p. 324), the only analysis that was made of water from this source, represents an extremely hard water. WATER SUPPLIES FOR CITIES AND VILLAGES. Renville. — The granitic surface seems to be somewhat irregular in the vicinity of Renville. The assertion is made that it was encountered 320 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. at a depth of 250 feet in drilling done for the village, but in the railway well a considerably greater depth was reached before granite was struck (PI. XV). Meager supplies of hard water are obtained near the surface, and more abundant supplies of softer water from the deposits of sand and gravel at the base of the drift (between about 190 and 265 feet below the surface), but no deeper water zones exist. The public supply is derived from a well 236 feet deep, winch has already been referred to (pp. 314-315). About 300 people use the water, and 10,000 gallons is consumed daily. An analysis is given in the table. Perhaps three-fourths of the inhabitants use water from private wells, which have an average depth of about 25 feet and are generally cased with wood or brick. The railway company uses a well that admits water from the sand stratum between 240 to 264 feet below the surface. Olivia. — When the deep drilling for the village of Olivia was done the stratigraphic record was carefully kept, and tins record forms the basis of the section given in Plate XV to a depth of 349 feet. There is some uncertainty as to the exact depth at which the decomposed granite was entered. The upper portions of the glacial drift yield small amounts of hard water, but the sand and gravel at a depth of about 300 feet, at the base of the drift, furnish adequate quantities of softer water. The public supply is obtained from a well 320 feet deep, the data in regard to which have already been given. The water, an analysis of which will be found in the table (p. 324), has little permanent hard- ness and will not form much hard scale in boilers. About 250 people use the water, and it is also used at the canning factory, mill, and laundry, approximately 17,000 gallons being consumed daily. The creamery is supplied from a shallow well which yields harder water, and about three-fourths of the people use water from private wells, most of which are dug or bored and end in yellow clay or sandy deposits at depths of 20 to 30 feet. One private drilled well similar to the village well was reported. Bird Island. — There are several water-bearing beds in the glacial drift at Bird Island, the upper ones yielding harder water than those that lie deeper. Apparently there is no water-bearing formation at a greater depth than 230 feet (PI. XV). The public supply is obtained from an 8-inch well which was drilled to a depth of 298 feet but which receives its water from about 200 feet below the surface. As the analysis in the table shows, the water has little permanent hardness and will not form much hard scale in boilers. Approximately 16,000 gallons is reported to.be consumed daily, but only a small proportion of the inhabitants use the public water. The majority of the private wells are dug or bored to depths U. S. GEOLOGICAL SURVEY WATER-SUPPLY PAPER 256 PLATE XV options IN RENVILLE COUNTY. GEOLOGIC SECTIONS m By 0. E. Meinzer. „ .„ . Bird Island.— Railway well; reported by Mi". Hayden. teu(W 'V^wy well. Authority, Mr. Hayden, water-supply supenn- Hector.— Railway well; reported by Mr. ^^ „ f dri Urngs aud from ml • ^^ and Dakota division, Chicago, Milwaukee and St. Paul Bufialo La ke.^Village wells; from an examination ? a .y, blencoe. various reports. an(lrmt7^ eu PP el ' 349 £ eet represents deep drilling done for the village ^ported by the village authorities. RENVILLE COUNTY. 321 of about 20 to 40 feet, but there are also a few drilled wells which obtain more satisfactory supplies from about 200 feet below the surface. The railway company is supplied from a well that was drilled to a depth of 375 feet but derives its water from between the depths of 190 and 230 feet. Fairfax.— Water is obtained at Fairfax from the various beds in the glacial drift and from a sandy zone between the white clay and the decomposed granite. (See the section given above.) The public waterworks are supplied from a 6-inch well which is finished with an open end in a layer of sand at a depth of 185 feet, gravel having been put into the well to act as a screen. It is pumped at 10 or 20 gallons a minute and should not be pumped at a more rapid rate as long as it has an open end. The water, which is used only to a small extent, is hard and is objected to because of the iron which it contains. Most of the private wells are bored or dug into the yellow clay or sand near the surface and are readily afTected by drought, but there are a few deeper drilled wells. The well at the flouring mill, which is 234 feet deep and derives its supply from immediately above the granite, yields water that is reported to be harder than that from the glacial drift. This water probably belongs to the same type as that from John Eder's well, north of Morton, an analysis of which is given in the table. Hector. — At Hector the best water-bearing bed, both as to quality and quantity, is the deposit of sand and gravel immediately above the granite (PI. XV). The public supply is obtained from two wells. The old well has a depth of 380 feet, of which the upper 35 feet is 12 feet in diameter and cased with brick and the remaining portion is 9 inches in diameter and has an iron casing with a screen at the bottom. The new well is 400 feet deep and 8 inches in diameter and is also finished with a screen. The water is relatively soft and will form almost no hard scale in boilers. An analysis is given in the table. At the time the waterworks were visited (1907), the combined yield of the two wells was small and inadequate, but it seemed probable that this was due to some mechanical difficulty rather than to the limitations of the water-bearing bed itself. When the new well was completed (1902), it is reported to have been pumped at the rate of 60 gallons a minute for twelve hours continuously. By far the greater number of the people use water from private wells, most of which are shallow. The railway company has an 8-inch well that was drilled to a depth of 728 feet but derives its supply from the sand and gravel above the granite. An analysis of this water, which resembles that from the village well, will be found in the accompanying table (p. 324). The mill also is supplied from a deep well. 60920°— wsp 256—11 21 322 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Morton. — The village of Morton is situated on the north bank of Minnesota Kiver and lies in the valley and on the valley side. The granite is at or near the surface and there is no deep water-bearing bed. There are numerous springs on the flanks of the valley, one of which, situated east of the village and at a higher altitude, fur- nishes the public supply. The water from this spring flows directly into the mains and gives a pressure sufficient for ordinary purposes, and water pumped from the spring into a reservoir on the uplands furnishes the greater pressure necessary in case of fire. The yield of this spring is not great. At the time it was visited (1907) it did not supply the pump operated at the rate of about 30 gallons a minute, and in dry years the yield is reported to be inadequate. The water is hard, as is shown by the analysis given in the table. Perhaps one-fourth of the people use water from private wells, most of which are shallow and furnish only meager supplies. Sacred Heart. — Deep drilling has never been undertaken in Sacred Heart, but it is probable that the granitic rocks occur at no great depth. The public supply is obtained from a well 14 feet in diameter and 40 feet deep, which is cased with brick and mortar. It passes through yellow and blue bowlder clay and ends in a layer of coarse sand. In 1907 the water normally rose within 18 feet of the surface, and pumping at the rate of 50 gallons a minute for four hours con- tinuously lowered this level 4 or 5 feet. The water is used by about 125 people, perhaps 80 per cent of the inhabitants being supplied from private wells, which are generally dug to a depth of about 30 feet and end in sand or gravel. Franklin. — Franklin village is located on the level upland near the cliffs of the Minnesota Valley. The glacial drift is about 120 feet deep, the basal 10 feet of it consisting of water-bearing sand and gravel. Below the drift are the white clay and the granitic rocks. (See the section given above.) The public supply is obtained from a well 6 feet in diameter and 108 feet deep, which is cased with boiler iron. This well reaches to the sand and gravel layer mentioned above. The upper portion of the layer consists of very fine sand, which was prevented from rising in the well by covering the bottom with 5 wagonloads of gravel. In 1905, when the well was completed, it was pumped at the rate of 50 gallons a minute for forty-eight hours continuously, whereby the water was lowered 14 inches. About 500 people are supplied, and approximately 10,000 gallons is consumed daily. There are only a few private wells, and these are shallow and readily affected by drought. Buffalo Lake. — At the village of Buffalo Lake there is a thin layer of water-bearing sand or gravel at a depth of about 100 feet and another at about 200 feet, both of which belong to the glacial drift. RENVILLE COUNTY. 323 Granite occurs at about 320 feet or somewhat lower, and immediately above the granite there is a little water, but not enough to furnish a satisfactory supply. The public supply is derived from two wells, both of which were drilled to depths between 300 and 400 feet (PI. XV). The present supply of the old well comes from the 100- foot gravel bed; the new well seems to obtain its water above the granite. The yield of each is small. Most of the people use water from shallow private wells, but there are a few private drilled wells which end in the 100-foot zone, and the well at the mill is reported to be about 400 feet deep. FARM WATER SUPPLIES. In the northern part of the county most of the farms are supplied from shallow bored wells which end in the upper portion of the drift and yield meager and uncertain quantities of hard water, but there are a few deeper drilled wells similar to the village and railway wells along the Chicago, Milwaukee and St. Paul Railway. The deep wells are superior to the shallow ones in the following respects: (1) The water is softer, (2) the yield is larger and more permanent, and (3) there is less danger of pollution. In the southern part of the county there are more drilled wells. These range from 2 to 6 inches in diameter, and from less than 100 to more than 300 feet in depth, but are generally between 100 and 150 feet. They generally end in the glacial drift, but a few penetrate the underlying formations, as has already been explained. The shallow wells have hard water but some of the deeper ones yield water which is softer. Six-inch drilled wells are recommended for farm purposes in all parts of the county. SUMMARY AND ANALYSES. The principal sources of water are the deposits of sand and gravel which occur at various depths interbedded with the bowlder clay or lying immediately below it. The shallow deposits furnish only small supplies but the deeper ones generally yield abundantly. Moreover, the shallow water is hard and the deeper water is commonly much softer, especially in the northeastern part of the county. Below the glacial drift the drill generally penetrates thin layers of blue or green shale "soapstone", a white clay, or ordinary decom- posed granite. In the southern part of the county water is obtained in some places from sandy layers in these beds, but at best the3^ con- stitute only an uncertain source. Granite has frequently been encountered at depths ranging up to 450 feet. It will not yield water and no water-bearing formation occurs beneath it, 324 UNDERGROUND WATERS OE SOUTHERN MINNESOTA. Mineral analyses of water in Renville County. [Analyses in parts per million.] Depth feet. . Diameter of well inches. . Silica (Si0 2 ) Iron ( Fe) Aluminum ( Al) Iron and aluminum oxides (Fe2C>3+ AI2O3) . . . Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+K) Carbonate radicle (C0 3 ) Bicarbonate radicle (HCO3) Sulphate radicle (SO*) Chlorine (CI) Nitrate radicle (N0 3 ) Total solids Surface deposits (glacial drift, etc.). Upper portion. 342 147 6 4 267 123 25 360' 452 280 80 1.456 283 108 65 555 795 6 1,538 Spring. 48 113 34 12 449' 69 3 519 Lower portion. 160 190 211 6 59 3.8 2.8 4.5 4.5 56 63 149 31 29 79 84 103 100 .0 463 452 528 13 104 417 40 13 13 Depth feet. Diameter of well inches. Silica (Si0 2 ) Iron (Fe) Aluminum ( Al) Iron and aluminum oxides (Fe20 3 -|- AI2O3) . . . Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+ K) Carbonate radicle (CO3) Bicarbonate radicle (HCO3) Sulphate radicle (SO*) Chlorine (CI) Nitrate radicle (N0 3 ) Total solids Surface deposits (glacial drift, etc.). Lower portion. 236 6 19 3.2 67 25 120 .0 473 123 14 610 10. 11. 12. 13. 14 320 6 20 1.4 42 23 122 457 1 11 2.8 45 28 111 .0 522 17 13 483 298 390 8 20 .08 4.5 9.3 55 58 27 40 67 133 .0 660 40 400 8 11 8.1 4.6 40S 66 46 115 650 43 16 White clay. 140 2.4 339 159 35 .0 508 1,120 3 1,945 1. Former village well at Renville. April 24, 1S93. 2. Well at the Commercial Hotel at Buffalo Lake. September 13, 1907. 3. Former railway well at Bird Island. May 6, 1S94. 4. Springs which furnish the public supply at Morton. August 31, 1907. 5. Well on the farm of John Ford, sec. 1, t. 113 N., R. 34 W. August 31, 1907. 6. Former railway well at Renville. October 13, 188S. 7. Railway well at Renville. April 24, 1S93. 8. Village well at Renville. September 7, 1907. 9. Former village well at Olivia. January 23, 1901. 10. Village well at Olivia. September 12,' 1907. 11. Village well at Bird Island. September 12, 1907. The water comes from a depth of about 190 feet. 12. Well of Berry Brothers at Hector. August 4, 1S99. 13. New village well at Hector. September 13, 1907. 14. Railway well at Hector. December 4, 1900. 15. Well oh the farm of John Eder, 1 mile north of Morton. August 31, 1907. Analyses 2, 4, 5, S, 10, 11, 13, and 15 were made for the United States Geological Survey by H. A. Whit- taker, chemist Minnesota state board of health. Analyses 1,3,6, 7, 9, 12, and 14 were furnished by G. N. Prentiss, chemist Chicago, Milwaukee and St. Paul Railway Company. RICE COUNTY. By C. W. Hall and M. L. Fuller. SURFACE FEATURES. The upland surface of Rice County ranges from 1,000 feet above sea level near the northwestern corner to 1,200 feet near the south- eastern corner. The greater portion, though rolling, is nearly uni- RICE COUNTY. 325 form in elevation, but the general level is broken by the valleys of the Cannon and its tributaries and by morainal ridges which rise 50 to 100 feet above the surrounding region. The more easterly of these ridges is an interrupted belt of irregular hills crossing the country from north to south a little east of Faribault. South of this city, where the ridge is about 6 miles wide, it is cut near the middle by the valley of Straight River. The other moraine is much broader, covering the western third of the county and having a maximum width of 12 miles, a part of which, however, lies within Lesueur County. Between the two moraine belts there are numerous un- trained depressions containing lakes and marshes, but in the western aoraine lakes are even more abundant. East of the eastern mo- raine the surface is much broken by the valley of Cannon River and by the valleys tributary to Cannon and Zumbro rivers, but remnants of the plateau still remain. The principal stream, Cannon River, crosses the county from the southwestern to a point near the north- eastern corner, occupying a valley 100 to 200 feet deep, the bottom of which is in rock north of Faribault. The smaller streams have valleys reaching 100 feet in depth and likewise in many places flow over rock, especially in the northeastern part of the county. Ter- races one-half to 2 miles or more in width occur along Camion River. SURFACE DEPOSITS. The glacial drift is a heterogeneous pebbly clay with some bowlders and interbedded bodies of sand and gravel. Several stages of deposi- tion are represented, the older drift forming a belt several miles wide along the eastern border and extending westward beneath the younger, which covers the central and western parts of the county. Both contain sandy or gravelly layers, but these are distinctly more numerous in the younger drift than in the older. The total thickness varies from less than 50 feet along the river valleys to more than 200 feet in the western part of the county. Water occurs in considerable quantities in the sandy and gravelly layers and is most abundant, because these porous layers are more numerous in the younger drift of the western part of the county. The supplies are nearly everywhere sufficient for domestic and farm purposes and are generally ample for the needs of small industries. The terrace gravels include the deposits made by glacial streams flowing, from the ice sheet lying to the west, through the Cannon River valley to the Mississippi. In the upper courses of the river they occupy the full width of the valley, but in the central and north- ern part of the county the stream has at present cut far below their level and has left them standing as terraces, in some places, as at Faribault, from 1 to 2 miles or more in width. There are two distinct series of terraces, a lower series, upon which Faribault is situated, about 45 feet above the river, and an upper series at a considerably 326 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. higher level. Their height above the river, however, varies from place to place, becoming greater downstream toward the north. The gravel of which the terrace deposits are composed readily absorbs the water falling on its surface, but it permits an equally ready escape to the valleys, for this reason the supplies are usually small near the drainage lines. During the northward retreat of the ice a small lake was formed in front of its margin in the valley of northward-flowing Straight River. In this lake were laid considerable amounts of sand and gravel of essentially the same character as the terrace deposits. Elsewhere in the county there are many areas of stratified gravel and sand, interminably intermingled with the terraces on the one hand and with the unmodified drift on the other. The alluvial deposits include the gravel and sand laid down by the existing streams. They are not extensively developed and are of little importance with regard to water supplies. Wherever drawn upon they yield enough for domestic use. PALEOZOIC FORMATIONS. The Galena limestone, Decorah shale, and Platteville limestone are all present in this county, with an aggregate thickness of about 130 feet. Outcrops of the Platteville limestone are found along Cannon River, and the Galena limestone lies immediately beneath the drift on the uplands near the southeastern corner of the county. From well records the Platteville limestone also appears to lie beneath the drift of the uplands throughout extensive areas in the north- western part of the county. The Galena and Platteville limestones furnish only small supplies of water. The St. Peter sandstone, which varies in thickness from 160 feet to an eroded remnant of only a few feet, is exposed along Cannon River from a point above Faribault and lies beneath the uplands both east and west of this stream. To the east, and especially to the southeast, it generally underlies the Platteville limestone and affords good supplies of water under some pressure. Northwest of the Cannon the Galena, Decorah, and Platteville formations are generally missing and the St. Peter lies immediately below the drift. In such localities the water is not under much pressure and does not enter the wells as freely as when the forma- tion is under cover, though nearly everywhere supplies sufficient for domestic and farm purposes can be obtained. Thirty-five feet of Shakopee dolomite, a buff to pinkish magnesian limestone, is exposed in the Cannon River valley at the north line of the county. The formation probably occurs immediately beneath the drift near the northwest corner and it underlies the St. Peter through- out the remainder of the county. The New Richmond sandstone, which probably attains a thick- ness locally of 25 feet, dips southeastward below the Shakopee and RICE COUNTY. 327 contains water under pressure at practically all points within the county. It affords a valuable supplementary supply where the St. Peter sandstone is not under cover or where its supplies have been lessened by heavy pumping. The Oneota dolomite, a bed of pinkish magnesian limestone attain- ing 150 feet in thickness, lies beneath the New Richmond and affords a cap to confine the waters of the underlying Jordan sandstone. The Jordan sandstone, which should be reached at 200 or 225 feet below the bottom of the St. Peter, is a porous sandstone about 90 feet thick, saturated with water under sufficient pressure to cause it to enter wells freely. It constitutes a stronger water zone than any above it and is valuable where large supplies are required. Below the Jordan are the shales and limestones of the St. Law- rence formation, about 140 feet thick; the Dresbach sandstone, about 90 feet thick; and the underlying basal Cambrian shales and sandstones, probably reaching 350 feet in thickness. The sandstones are saturated with water under considerable pressure and afford valuable supplementary supplies to the St. Peter and Jordan wherever they are reached by wells. UNDERGROUND WATER CONDITIONS. Wells. — As is usual where the surface materials are mainly drift, water is easily obtained in the sandy and gravelly layers at a short distance below the surface by open or bored wells. However, drilled wells are also common because the water in the deeper beds of the drift give a more permanent and reliable supply than do the shallow beds. In the eastern part of the county many of the upland wells pass through the drift, which in many localities does not much exceed 100 feet in thickness, and enter the underlying rocks. In the valleys driven wells sunk into the alluvium or terrace gravels are the most common source of water, but for large supplies, such as the public supplies of Faribault and Northfield, deep wells drilled to the Jordan or some lower sandstones are necessary. Head of the water. — In the middle and lower portions of the drift the water always stands under considerable head, but no flowing wells from the drift have been reported in this county. In the Paleozoic sandstones, the head of water is a more nearly constant factor. Thus at Faribault and Northfield, situated in the Cannon River valley, strong flows are obtained, the water rising 10 or 20 feet above the surface, but on the uplands the Paleozoic sandstones will not give rise to flows. WATER SUPPLIES FOR CITIES AND VILLAGES. Faribault. — The city of Faribault has a system of water supply derived from two deep wells, which tap the Jordan and Dresbach 328 UNDERGROUND WATERS OP SOUTHERN MINNESOTA. sandstones. The section of the deeper of the two is approximately as follows : Section of public well at Faribault. Thick- ness. Depth. St. Peter sandstone, in part Shakopee dolomite, New Richmond sandstone, and Oneota dolomite (estimated) Jordan sandstone (estimated) St. Lawrence formation (shales) (estimated) Dresbach sandstone and underlying shale (entered) 225 355 Feet. 75 340 420 645 1,000 Several other wells in the city have been sunk to the deep-water zones; for instance, the one at the Consolidated Gas and Electric Light Company's plant and the one at the school for the deaf and dumb. In the bottom of the valley the water rises approximately to the surface. A number of analyses of water from various depths are given in the accompanying table (p. 329). Northfield. — The city of Northfield has a public supply drawn from an artesian well sunk in 1894. This well was originally 647 feet deep, but in order to obtain water of less hardness it was plugged at a depth of 300 feet, and the supply now comes from the Jordan sandstone. The water will rise 20 feet above the surface and the flow from an 8-inch casing is reported to be 1,000 gallons a minute. The section of the well is as follows : Section of public well at Northfield. Thick- ness. Depth. Shakopee, New Richmond, and Oneota Jordan (white sandstone) St. Lawrence (blue shale) Sandstone (Dresbach ?) Shale >- . - Sandstone Shale Sandstone Limestone Feet. 265 50 225 20 3 15 9 35 25 Feet. 265 315 540 560 563 578 587 622 647 The water from several water-bearing beds penetrated in this well was examined by the Minnesota state board of health, with the follow- ing results: Analyses of water from the Northfield city well. [Parts per million. Authority, C. F. Loweth, civil engineer.] Depth. Residue. Chlo- rine. Hardness. Vola- tile. Fixed. Total. Tem- porary. Perma- nent. Total. Feel. 82 500 647 51 85 15 320 295 435 371 380 450 4.69 2.85 j. 75 72 82 294 148 158 146 220 240 440 RICE COUNTY. 329 Lonsdale. — The village of Lonsdale has a public water supply, which, however, is not extensively used by the people, nearly all of whom have private wells. SUMMARY AND ANALYSES. When large supplies are required drilling should be continued to one of the Paleozoic sandstones that underlie the county and contain large stores of water, which they yield generously. For farm and domestic purposes it is generally possible to obtain, from shallower sources and at less expense, supplies which are adequate and, more- over, occcur under better head than those from the deep zones. On the uplands deep drilling should not be undertaken for the purpose of obtaining flowing wells. Mineral analyses of -water in Rice County. [Analyses in parts per million.] Glacial drift. Depth feet.. 12 and 30 Silica (Si0 2 ) 30 Iron (Fe). Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+K). Bicarbonate radicle (HCOi) Sulphate radicle (SO4) Chlorine (CI) Total solids 9.2 73 21 13 E29 25 5. 309 1.0 81 26 10 350 38 3.8 334 70 "i'3 ISO 226 37 7.9 352 205 94 52 502 169 164 1,174 130 45 40 61 569 43 41 594 42 23 573 44 482 Depth feet. Silica (Si 2 ) Iron(Fe) Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+K). . Bicarbonate radicle (HC0 3 ) Sulphate radicle (S0 4 ) Chlorine (CI) Total solids New Richmond sandstone. 9. 10. 11. 322 76 227 20 18 6.5. 2.7 1.9 103 91 87 41 31 30 42 13 1.9 543 4<9 410 24 14 16 2.2 1.2 3 509 376 350 Jordan sand- stone. Dresbach sandstone. 12. 13. 14. 15. 16. 17 647 647 500 600 600 825 3.9 3 96 2.6 21 12.7 .2 97 92 97 96 91 34 32 30 32 29 29 5.1 12 21 34 11 21 378 437 407 417 410 407 69 32 46 82 38 46 7.9 1.2 10 18 3 11 352 391 402 490 392 400 18. 1,000 1.7 99 30 9.4 431 3S 1.2 391 1. Former city well at Faribault. June, 1892. 2. Well at Faribault. September, 1892. 3. City weh at Faribault. April, 1899. 4. Well of Joseph Marek at Lonsdale. December, 1901. 5. Well of F. Shiask at Lonsdale. Mav, 1902. 6. Well of T. Wilbey at Lonsdale. December, 1901. 7. Well of T. Wilbey at Lonsdale. May, 1902. 8. Well of J. Malscha at Lonsdale. May, 1902. 9. Village well at Lonsdale. November, 1906. 10. Chicago, Milwaukee and St. Paul Railway well at Northfield. August, 1890. 11. Northfield Hemp Company's well at Northfield. November, 1906. 12. City well at Northfield. January, 1896. 13. City well at Northfield. July, 1895. 14. Well at the school for the deaf and dumb at Faribault. April, 1896. 15. Consolidated Gas and Electric Light Company's well at Faribault. October, 1893. 16. Well supplying the waterworks at Faribault. September, 1896. 17. Well at the school for the deaf and dumb at Faribault. 1896. 18. City well at Faribault. July, 1895. Analyses 1 to 8, 10, 13, and 18 were furnished by G. N. Prentiss, chemist Chicago, Milwaukee and St. Paul Railway Company. Analyses 9 and 11 were made by II. S. Spaulding. Analyses 12 and 14 to 17 were furnished by the Dearborn Drug and Chemical Company, Chicago. 330 UNDERGBOUND WATEES OF SOUTHEEN MINNESOTA. ROCK COUNTY. By O. E. Meinzer. SURFACE FEATURES. The surface of Rock County is a gently undulating prairie which differs from that of the counties farther east in being much better drained and in being essentially free from lakes and swamps. The north-central section is occupied by a low rock plateau, which is ter- minated abruptly on the southeast by a bold quartzite cliff. This part of the plateau stands about 175 feet above Rock River and is known as "the Mound." The south-facing cliff becomes lower toward the west and terminates within a short distance, but that facing the east is more persistent and appears in low rocky outcrops approximately to the north boundary. Rock River, which is the largest stream, flows southward through the eastern portion of the county, occupying a wide open valle} T and receiving numerous tributaries, which reach it through more narrow and gorgelike valleys. The western half is drained b} r several smaller streams that flow toward Big Sioux River in South Dakota. SURFACE DEPOSITS. i Description.— -The surface deposits of Rock County consist chiefly of glacial drift. The valleys contain extensive alluvial deposits, which are in large part of glacial origin. In the northwestern and north-central portions of the county the drift is thin or entirely absent and the quartzite lies near the surface. This area of attenuated drift comprises Rose Dell Township (T.104 N., R. 46 W., and T. 104 N., R. 47 W.), all but the eastern margin of Denver Township (T. 104 N., R. 45 W.), and all but the southern margins of Mound Township (T. 103 N., R. 45 W.) and Spring Water Township (T. 103 N., R. 46 W., and T. 103 N., R. 47 W.). (See Pis. II and III and also the list of rock wells given below.) Eastward and southward from this area the drift thickens rapidly, and within a few miles is so deep that the rock is rarely reached in drilling. The only rock well reported east of Rock River is on the farm of H. Enge- bretson (NE. { sec. 4, T. 103 N., R. 44 W.), where quartzite was struck at a depth of 157 feet. Only a few rods south of the Mound (NE. \ sec. 34, T. 103 N., R. 45 W.) the drift was found to be 200 feet thick, and at Luverne deep drilling has been done without encountering rock. Yield of water. — At many points where the drift is thin the quantity of water that it will furnish is quite inadequate, but where it has a considerable thickness copious supplies are drawn from the deeper portions. The deposits of sand and gravel in the valleys of Rock River and other streams will surrender their water very freely and are not easily affected by drought. The public supplies of Edgerton and Luverne and of several villages in Iowa located in the Rock River valley are obtained from this source. EOCK COUNTY. 331 Head of the water. — The water from the drift generally rises near the surface, and on the relatively low ground surrounding a quartzite ridge or plateau conditions are peculiarly favorable for producing flows. The rock here affords the intake area through which the water is transmitted to the water-bearing beds of the drift, and the imper- vious bowlder clay, which laps up over the rock plateau and extends as a continuous sheet to an altitude considerably higher than the surrounding surface, acts as a confining bed that allows the water to accumulate sufficient head to rise nearly or quite to the level of the lowland surface (fig. 4). An area in which flows are produced in the manner just outlined extends from the low ground east of Hardwick southeastward to Rock River (PL IV). Wells near the rock plateau have a head that is uncommon for the drift, but the pressure dimin- ishes rapidly with increase in distance from the plateau, and no flows have been obtained east of the river. The following wells are located in this area : Flowing ivells near Hardwick. Natural Owner and location. Depth. Diam- eter. Head relative to surface. flow (gal- lons per minute). Feet. Inches. Feet. E. T. Thorsen, SE. J sec. 25, Denver Township (T. 104 140 G Several above. Several. N., R. 45 W). O. Halverson, NE. | sec. 36, Denver Township (T. 104 125 6 More than 20 Many. N., R. 45 W). above. H. R. Halverson, SW. \ sec. 31, Battle Plain Township 114 6 More than 20 Many. (T. 104 N., R. 44 W).a above. I. Smotel, SE. >- sec. 6, Vienna Township (T. 103 N., R. 110 Several above. Few. 44 W.). F. C. Mahony, SE. 1 sec. 5, Vienna Township (T. 103 N., 147 C) C) R. 44 W.). — Halverson, SE. }- sec. 12, Mound Township (T. 103 N., 110 G below None. R. 45 W.). H. Engebretson, NE. \ sec. 4, Vienna Township (T. 103 180 6 6 below None. N.,R. 44 W.). c a The water forced its way up on the outside of the casing and made a large hole. A new well was drilled to the same zone. b A feeble flow was obtained at this depth, but drilling was continued 4 feet deeper through clay into a second seam of sand and gravel, the first seam being cased out. The water then remained 4 feet below the surface, and when the casing was drawn .back to the first seam it would not rise again to the surface. c This well is in rock below the depth of 157 feet. No other flowing wells from the drift were reported, but it is not improbable that others could be procured near the margins of the rock plateau, for they exist outside of this county in similar locations. A well several hundred feet deep was once drilled at Luverne for the purpose of getting a flow, but the project ended unsuccessfully. Quality of the water. — The water from the surface deposits is all hard, but the ordinary glacial drift water is generally more highly mineralized than that from the alluvial and outwash deposits. (See the analyses given in the accompanying table, p. 336.) CRETACEOUS SYSTEM. Cretaceous rocks are frequently encountered in southwestern Minnesota and northwestern Iowa. At Ellsworth, which is less than 332 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. 2 miles east of this county, shale and unconsolidated sandstone belonging to this system were found between the depths of 190 and 280 feet, and it is altogether probable that these deposits extend into the eastern and southern portion of this county. The sand- stone will usually afford liberal quantities of hard water. (See the report on Nobles County.) SIOUX QUARTZITE. Description. — The Sioux quartzite, or "red rock," is for the most part a hard, red, siliceous formation of nearly uniform character and great thickness. But though it is generally very firmly cemented there are marked differences in the degree of hardness, some layers of incoherent sand being encountered. There is also considerable variety in the color, which ranges from light pink to dark purple. The formation is distinctly stratified, in many places cross-bedded and ripple-marked, in general has a gentle dip, and is much broken by joints. It has been penetrated only a few hundred feet in this county and the bottom has never been reached. Throughout the northwestern and north-central parts of the county this rock lies near the surface and is exposed in a number of localities. Toward the east and south it slopes rapidly downward and within a short distance is deeply buried, but it again appears near the surface along the southern margin of the county (PI. III). The following is a representative list of wells which enter the quartzite, together with the depth to rock and the distance it has been penetrated, as given by drillers and other persons : Table of typical wells in Sioux quartzite of Rock County. Owner and location. L. II. Gilbertson, E. £ sec. 2(1, T. 104 N., R. 47 W... J. Kohler, SE. J sec. 2, T. 104 N., R. 47 W Aug. Beyer, S. 4 sec. 21, T. 104 N., R. 46 W E. lleckman, NE. ]- sec. 21, T. 104 N., R. 46 W C and O. Houg, N. I sec. 22, T. 104 N., R. 46 W.. .. C. and O. Houg, N. \ sec. 22, T. 104 N., R. 46 W.. . . J. J. Houg, NE. J- sec. 15, T. 104 N., R. 46 W G. C. Huntington, NW. \ sec. 2, T. 104 N., R. 46 W . F. A. Hyke, SE. \ sec. 22, T. 104 N., R. 46 W H. Larson, SE. J sec. 3, T. 104 N., R. 46 W F. Seeman, SE. i sec. 11, T. 104 N., R. 46 W K. K. Steen, NW. \ sec. 14, T. 104 N., R. 46 W W. E. Stork, NE. J sec. 4, T. 104 N., R. 46 W G. W. Vickerman, SE. \ sec. 20, T. 104 N., R. 46 W. H. Wiese, NE. } sec. 28, T. 104 N., R. 46 W P. E. Brown, SW. J sec. 15, T. 104 N., R. 45 W L. M . Grandy, SE. J sec. 14, T. 104 N., R. 45 W Hardwick citv well Henry Lamp^ N. 4 sec. 1, T. 104 N., R. 45 W A. J. Nickev, NE. \ sec. 9, T. 104 N., R. 45 W J. Sand, E. 4 sec. 21, T. 104 N., R. 45 W H. J. Stammon, NE. \ sec. 17, T. 104 N., R. 45 W . . . A. Barck, E. I sec. 22, T. 103 N., R. 45 W W. and A. Dysart, E. \ sec. 15, T. 103 N., R. 45 W . F. A. Hyke, SE. \ sec. "23, T. 103 N., R. 45 W J. E. Mitchell, NE. \ sec. 34, T. 103 N., R. 45 W .... W. A. Moore, NW. \ sec. 11, T. 103 N., R. 45 W J. Welzenbach, SW. \ sec. 14, T. 103 N., R. 45 W. . . H. Engebretson, NE. \ sec. 4, T. 103 N., R. 44 W . . . Depth to Sioux quartzite. Fed. 105 106 70 is 200 60 18 157 Distance drilled in Sioux quartzite. Fed. 55 45 158 14S 86 237 214 215 194 174 100 119 100 334 171 101 340 57 134 145 152 162 351 45 281 1SL> 23 Total depth of well. 160 151 160 160 93 243 234 300 200 180 160 337 137 108 335 223 168 420 284 217 220 222 ISO 358 45 200 341 200 ISO ROCK COUNTY. 333 In the area in which the Sioux quartzite is near the surface it lies immediately below the glacial drift, but in much of the eastern and southern parts where it has not been reached in drilling the Cretaceous shales and sandstones probably intervene between it and the drift. Yield of water. — In general the quartzite is so firmly cemented that there are virtually no pore spaces through which water can be transmitted. Nevertheless, the great dearth of water in some locali- ties forced the experiment of drilling into this rock, and in almost all the wells it yielded some water; it is now depended on as a reliable source of supply. The water percolates through the formation in two ways — (1) through the " crevices," that is, the system of joints into which the rock is broken, and (2) through the less firmly cemented portions. Occasionally a well will find a large " crevice" or very porous layer that will deliver generous quantities of water, but more commonly the "crevices" are small and the beds are but slightly pervious, so that only minute amounts of water are given up, and it is only by continued drilling, bringing the well in contact with many of these water-bearing elements, that an adequate supply is obtained. However, the yield generally increases with the depth in more than a direct ratio, and therefore doubling the depth does not merely double the supply but may augment it many fold. There seem to be two reasons for this — (1) the pressure with which the water enters the well increases with the depth, and (2) the water-bearing layers appar- ently are more abundant and more porous at lower levels. On the other hand, the fissures are perhaps less abundant and open at rather great depths than near the surface, but the rock has such great strength that this counteracting factor is not important for zones thus far reached in drilling. In putting down farm wells it is customary to guarantee only 100 gallons an hour, though many wells will furnish much more. The village well at Hardwick, which is 420 feet deep and penetrates the rock for a distance of 340 feet, has been pumped for ten hours con- tinuously at the rate of 25 gallons a minute. The average depth of the farm wells is considerably less, as is shown by the list given above, and their average yield is accordingly less. Head of the water. — There is a flowing well on the low ground near the junction of Pipestone and Split Rock creeks (E. J sec. 26, T. 104 N., R. 47 W.). It has a depth of 160 feet, of which 55 feet is in rock, and its action is perhaps similar in principle to that of the flowing wells from the glacial drift described above. In general, flows can not be obtained from the quartzite. The height at which the water stands varies, depending on the topography and other factors. Quality of the water. — The quartzite itself contributes very little mineral matter, and where it is at or near the surface the rain may enter it without becoming mineralized and may remain soft and 334 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. almost free from dissolved solids. But in most localities the quartzite is covered with a mantle of drift, and as the drift contains much soluble matter the water is liable to be highly charged by the time it reaches the rock. Hence the quartzite water varies widely in its mineral content; but on an average it is softer and otherwise less mineralized than that from the drift, though the substances which it contains are the same and generally occur in approximately the same relative proportions. It is, however, characteristic of much of the quartzite water to have a small content of iron, perhaps chiefly because much of the water reaches the rock directly from the oxidized zone of the drift and so contains free oxygen, which keeps the iron out of solution but does not interfere with the other dissolved con- stituents. (See the analysis in the accompanying table, p. 336.) No. 3 is remarkably free from dissolved matter of any kind. WATER SUPPLIES FOR CITIES AND VILLAGES. Luverne. — The city of Luverne lies west of Rock River on a terrace about 25 feet above the level of the flood plain. Both terrace and flood plain are composed of alluvial sand and gravel saturated with water. The public supply is taken from two wells, each 19 feet deep, one 20 and the other 13 feet in diameter. They are located on the flood plain about 200 feet from the river. In July, 1907, the ground- water level was 10 feet below the surface, and pumping at the rate of 750 gallons a minute from the two wells lowered this level only about 3 feet. In dry years the supply is less copious. The water is only moderately hard, as is shown by the analysis given in the table (p. 336). It is used by most of the people, and approximately 100,000 gallons is consumed daily. Most of the private wells, though usually bored or dug only a short distance into the alluvium, furnish water freely. Hardwick. — In some parts of Hard wick village the quartzite out- crops and in others the drift is 100 feet thick, the rock surface being very irregular. The public waterworks is supplied by a 6-inch well 420 feet deep, all but SO feet of this depth being in rock. The water rises within 36 feet of the surface. The test of this well has been mentioned above (p. 333). The analysis in the table (p. 336) shows that the water is only moderately hard. There is no system of mams and little use is made of the supply except in dry years, when many of the shallow private drift wells fail. FARM WATER SUPPLIES. In the area of attenuated drift the inexpensive but unreliable shallow wells have gradually been replaced by the much more costly but also more satisfactory rock wells, until now there are scores of the latter and more are being sunk each year. At first drilling in the EOCK COUNTY. 335 quartzite presented serious difficulties, but 'by patience and skill these have now been almost entirely overcome, so that though the drilling of a rock well is still a slow and expensive process it is no longer an uncertain project. The special difficulties are discussed under the heading " Problems relating to wells" (pp. 87-88). The original cost of a rock well is relatively great, but such a well when once drilled will last an indefinite time without further expense, as there is no screen to become corroded. As the supply is generally nearly constant, the farmers content themselves with a small yield rather than go to the additional expense of drilling deeper. One hundred gallons an hour, which is the yield guaranteed by some drillers, appears very small, but it is enough to keep a windmill work- ing slowly and to supply amply the consumption on an ordinary farm. In the larger area where the quartzite is deeply buried the farm supply is derived from the glacial drift, or, locally, from the alluvial and outwash deposits. The wells in the drift are mostly of the shallow bored type, but there are also a few drilled wells. In the alluvial and outwash deposits satisfactory supplies are obtained from driven wells. SUMMARY AND ANALYSES. The following formations will yield water: (1) Alluvial and out- wash deposits, (2) glacial drift (proper), (3) Cretaceous sandstone, and (4) Sioux quartzite ("red rock"). The first are available chiefly in the wide valley of Rock River, where they furnish large quantities of water at shallow depths. The second constitutes the most valuable source throughout the eastern and southern parts of the county, where it has considerable thickness and affords large supplies. The third is believed to lie at a depth of several hundred feet in some localities in the eastern and southern parts of the county and, though it has not yet been utilized, would here probably yield liberally. The fourth contains a relatively small store of water, but if penetrated several hundred feet will generally furnish enough not only for farm purposes but also for ordinary industrial and public supplies. Where other formations are wanting it is invaluable. The water from the alluvial and outwash deposits is only moder- ately hard, and that from the quartzite varies, though it is com- monly rather soft; but the water from the drift is invariably hard, and the Cretaceous water is liable to be still less satisfactory. There is no water-bearing formation below the quartzite, and there is no prospect of obtaining either flowing wells or soft water by deep drilling. It is, of course, advisable to sink to a depth of several hundred feet either in the drift or in the quartzite if this is necessary to acquire an adequate supply. 336 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Mineral analyses of water in Rock- County. [Analyses in puns per million.] Silriace de- posits. Allu- vium. Glacial drift. Sioux quartsite. Depth feet - - Diameter of well inches. . Silica (SiOg) Iron (Ftt) Large. 16 Iron and aluminum oxides (FeaOs+AlaOs). Calcium (Cal Magnesium (Mg) dd and potassium (Na+K) Carbonate radicle (COjJ Bicarbonate radicle (HCOs) Sulphate radicle (SO-0 Chlorine (CI) Nit rate radicle ^ X Oj) Total solids 350 50 5 399 GO in 15a 42 .0 681 126 11 .0 58 24 5 106' 420 ti 12 .;; ., .. si" 36 .0 1. City wells at Luverne. 2. Well at the rear of E. Olson's blacksmith shop at Hardwick. Julv 30, UM.iT. 3. Spring on the farm of L. MePermott. SW. J sec. 25, T. 103 X.. R. 4"> W. Julv 29, 1907. 4. Village well at Hardwick. August 1. 1907. Analyses 2, 3. and 4 were made for the United States Geological Survey by H. A. YV hit taker, chemist Minnesota state board of health. Analysis 1 was furnished by Mr. C. X. Phiibrick, chief engineer City light and waterworks. Luverne. The analyst and date are not given. SCOTT COUNTY. By C. W. Hall and M. L. Fuller. SUKFACE FEATURES. Scott County is topographically the lowest county south of Min- nesota River. It has a maximum altitude of a little over 1.100 feet on Mount Herber and at one or two other points in the southern part, and a minimum of 090 feet on the flood plain of the Minnesota, its average altitude being- about 925 feet. The morainal accumula- tions in the eastern half of the county, though of no great height, are marked by hills of very irregular outline, interspersed with which are numerous depressions occupied by marshes and lakes. In the west- ern half of the county the surface is gently rolling, or even fiat, and is characteristic of the type of plateau which southeastern Minnesota represents. Its surface is broken in places by streams flowing in valleys, some of which are 150 feet or more in depth. On the north- west is the valley of the Minnesota, which lies 200 to 225 feet below the neighboring uplands and has broad, swampy, alluvial bottoms 1 to 3 miles in width. Bordering the alluvium, and lying 25 to 50 feet above it. are a number of low rock terraces, the principal examples of which are found near Shakopee, Merriam Junction, and Jordan. Still higher, at an elevation of 100 to 150 feet above the river, are a number of broad terraces known locally as •"prairies" — the Shak- opee, Belle Plaine, and Sand prairies near Jordan being the most SCOTT COUNTY. 337 important. A number of ancient stream channels lead eastward into Cannon River. SURFACE DK POSITS. The glacial drift has a thickness of over 200 feet along the river, but is thinner inland, where the rock rises in places nearly to the surface, as along the eastern edge of the county. The gravelly portions commonly carry an abundant store of water, which is avail- able to wells of moderate depth. Usually the supplies are sufficient for small industries, as well as for farm and domestic uses, but are not commonly adequate where much water is required. Alluvium is found principally along Minnesota River, but minor amounts are found along other streams. The boring at Belle Plaine revealed 200 feet of sands and gravels, but it is doubtful whether these consist entirely of alluvium. Rock shows through the deposits at a number of places, and it is probable that the average thickness of the alluvium is not more than 50 feet. It contains considerable amounts of water, but owing to the presence of silt its supplies are given up rather slowly. The terrace sands and gravels occur at a number of points along the Minnesota, especially south of Shakopee and southeast of Belle Plaine. They represent the deposits of glacial streams, their occur- rence at the present time as terraces being due to more recent erosion. The materials generally consist of clean sands and gravels, having a thickness of 30 to 40 feet and resting on benches cut in the underlying drift or in the more ancient Paleozoic rocks. They readily absorb the rain, but the water is quickly lost by drainage into the adjoining valleys, at least near the edges of the terraces. Farther back, and where there are depressions in the underlying drift surfaces, considerable water remains. PALEOZOIC FORMATIONS. The Platteville limestone occurs beneath the drift in the highest lands in the eastern and southeastern parts of the county, but its total thickness is probably not more than 20 feet. It is a protecting cap to the underlying St. Peter sandstone. The St. Peter sandstone, which probably exceeds 110 feet in thick- ness, is exposed at the surface nowhere within the county. It covers a broad area, however, beneath the drift and underlies the Platte- ville along the eastern border, stretching thence westward into the central part of the county. Where it lies immediately under the drift it is commonly reported as a loose sand rather than as a sand- stone; indeed many drillers fail to distinguish it from the glaciul drift. It appears to hold much more water than the drift and affords ample 60920°— wsp 256—11 22 338 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. supplies for most purposes. However, as the water is not under mueh pressure it does not enter the wells freely enough to furnish large supplies. The Prairie du Chien group is here represented by 150 feet of buff magnesian limestone, occasionally mottled with red and yellow, separated in the upper part by about 5 feet of sandstone, which is believed to represent the New Richmond sandstone. It outcrops along Minnesota River near the village of Shakopee, from which the upper dolomite derives its name. The rocks as a whole are character- ized by numerous joints, bedding planes, and solution passages which may contain water. Good supplies are generally obtained whenever it is possible to sink wells to the level of the adjoining river, which controls the water level in the limestone along its borders. Much of the water of the deep upland wells probably conies from the sandy bed, which is regarded as the equivalent of the New Richmond sandstone of other counties. The Jordan sandstone is about 1 25 feet thick. It is exposed at Jor- dan and along Minnesota River to the north. Southward it bends away from the river, leaving the limestone of the St. Lawrence forma- tion outcropping in the valley, but it returns again to the valley near the southwestern corner of the county. The formation is a magnificent water-bearing bed, furnishing, even along its outcrop, abundant supplies for ordinary domestic, farm, and industrial pur- poses, though the water rises but little. Under the uplands it consti- tutes an important source of supply to the deeper wells. The St. Lawrence formation here consists of a red or yellow shaly dolomite, having a total thickness of about ] 50 feet and outcropping along the eastern bank of Minnesota River. It carries very little water, but gives rise to a few springs of small size. Its principal value results from the fact that it serves as a cap to the underlying Dresbach sandstone, confining the water of the latter under consider- able artesian pressure. Beneath the St. Lawrence formation, at a depth of about 200 feet below tfye river in the southwestern part of the county, occurs the Dresbach sandstone, a water-bearing bed of the best character. Owing to the greater pressure upon its water, incident to its protected situation, it affords larger supplies and better head along the Minne- sota than does the Jordan. In the valley of the Minnesota it gives rise to flows. Farther back, beneath the uplands, the advantage of the Dresbach over the Jordan is not great. Below the Dresbach occurs a considerable thickness of Cambrian shales, underlain by sandstones whose characters and water supplies are very similar to those of the Dresbach sandstone. Their yield, however, is not materially greater than that of the Dresbach sandstone, and there is therefore generally no object in sinking wells to them. SCOTT COUNTY. 339 Many years ago the discovery of a slightly saline spring led to the drilling of a deep well at Belle Plaine for the purpose of prospecting for brine. The record of this well, together with the hypothetical correlation of the strata, is given below. Record of the Belle Plaine salt well. a Thick- ness. Depth. Alluvium and drift ( ?) Sandstone [basal Cambrian] Red ocherous sand and shale Purple shale mottled with white Red to greenish shale as above Red shale or marl Purple and mottled shale '. Red quartzite and shale Ocherous shale Dark-brown micaceous quartzite Dark greenish brown micaceous quartzite [Red clastic series:] Dark reddish brown quartzite and greenish shale. Iron-stained light green Red sandy shale Red, brown, and green shale Brown, red, and green shale [Sioux quartzite]: Shale and quartzite (entered) Feet. 216 16 10 40 108 6 24 20 10 10 10 50 10 20 40 24 Feet. 216 232 242 282 390 396 420 440 450 460 470 520 530 550 590 614 710 a Upham, Warren, Final Rept. Geol. and Nat. Hist. Survey Minnesota, vol. 2, 1885, pp. 117-119. The red clastic series, which is present everywhere in southeastern Minnesota, appears here to be 240 feet thick. The above section is significant in 'apparently showing the absence of the water-bearing Dresbach sandstone, which furnishes such desirable supplies at Chaska, Merriam Junction, and Henderson. The "Sandstone [basal Cambrian] " is apparently a remnant of this formation. Compare the Jordan well only 7 ov 8 miles away. (See p. 340.) UNDERGROUND WATER CONDITIONS. Wells. — Open wells obtaining supplies from sandy or gravelly layers only 15 or 20 feet below the surface were formerly the principal source of supply. They were found, however, to fail in times of drought, and drilled wells going to depths of 50 to 150 feet have been generally substituted, the supplies being obtained from sand or gravel beds in the drift. The deeper water is not only more ample, but, being beyond the reach of pollution, is much safer than that from the old shallow wells. Wells drilled to the rock are not common on the uplands, but nearly every township has one or more. In the valleys driven or drilled wells sunk in the alluvium or underlyimg drift are common where these deposits have considerable thick- ness, but where the rocks are near the surface, as at Shakopee, Jordan, etc., the wells nearly all enter the rock, obtaining water from the immediately underlying formation at depths of 30 to 50 feet or deeper. The supplies from the alluvium and surface rocks are rather meager. Hence where large supplies are required it is necessary to sink to the Dresbach or lower sandstones. 340 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. Head of the water. — Owing to the relief and the varied sources of supply, the range in the head of water relative to the surface is consid- erable. In the shallow wells ending in the upper part of the drift the water usually stands near the surface, but where the deeper drift is drawn upon the head is generally lower. Along the edge of the bluff bordering the Minnesota Valley it is not uncommon to have to lift the water from depths of 50 to 100 feet, but on the flood plain of the Minnesota the wells penetrating the Dresbach and lower sandstones overflow at the surface and may have a head of 25 to 50 feet above the river level. Springs. — Springs are common at the base of bluffs along the valleys of the Minnesota and its tributaries, and afford domestic and stock supplies for many farms. Most of them are small, but where the limestone is present to collect the water flows of considerable volume sometimes occur. The so-called Jordan mineral springs, owned by O. Rosendahl, have in recent years attracted considerable attention. They issue from the lower part of the bluff on the south side of the Minnesota Valley. The water is charged with sulphureted hydrogen and is reputed to have medicinal value. WATER SUPPLIES FOR CITIES AND VILLAGES. New Prague. — The city of New Prague has a public supply which is used by about three-fourths of the inhabitants. The water is obtained from an 8-inch well that is 289 feet deep. Belle Plaine. — A 'system of public waterworks has recently been installed in this city. The supply is taken from a well 8 inches in diameter and 213 feet deep. The underground conditions in this vicinity have already been discussed. Shakopee. — The city of Shakopee has no public supply, but is pro- vided with an engine and hose, the water being pumped from the river in case of fire. Jordan. — As the city of Jordan has no system of waterworks, all the people depend on private supplies, derived chiefly from water- bearing sand near the surface. The Minneapolis and St. Louis Rail- road well is supplied from the Dresbach sandstone, which was pene- trated at a depth of 210 feet. The water in this well rises within 4 feet of the surface, and the well has been tested at 125 gallons a minute. The section is given below: Well section at Jordan. [Authority, H. G. Kelley, chief engineer.] Thick- ness. Depth. Alluvium Shale and dolomite (St. Lawrence). Sandstone (Dresbach) Shale Feet. 112 98 75 2 Feet. 112 210 285 287 SIBLEY COUNTY. 341 Merriam Junction. — The following is the section of the Chicago, St. Paul, Minneapolis and Omaha Railway well at Merriam Junction. An analysis of the water is given in the table below. Well section at Merriam Junction. [Authority, J. F. McCarthy, driller.] Thick- ness. Depth. Alluvium Hard, crystalline dolomite (St. Lawrence) : Soft, shaly dolomite (St. Lawrence) Sandstone (Dresbach and possibly in part the red clastic series) (entered) Feet. 130 85 95 351 Feet. 130 215 310 661 SUMMARY AND ANALYSES. The beds of sand and gravel that are generally encountered on the uplands within 200 feet of the surface almost invariably yield sup- plies adequate for ordinary purposes, but still larger supplies can be obtained from the several sandstone formations at greater depths. < The water will rise nearer to the upland surface from the shallow zones than from the deeper one, but in the valley generous flows can usually be obtained from the deep sandstones, though the section of the so-called salt well at Belle Plaine gives a warning that these sandstones may locally vary in their water-carrying capacity. After the red clastic series is encountered the prospects of obtaining a satisfactory supply are poor. Mineral analyses of water in Scott County. [Analyses in parts per million.] Depth feet. Silica (Si0 2 ) Iron (Fe) Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+K) Bicarbonate radicle (HC0 3 ) Sulphate radicle (SO4) Chlorine (CI) Total solids 18 18 79 22 1.3 320 20 2.2 338 SO 20 Trace. 72 25 3.9 344 6 3.6 291+ /66and\ \ 106 4. 24 139 57 230 390 95 471 1,212 45 23 2.9 74 25 1.3 333 14 2.2 307 18 85 20 16 4.9 72 193 29 102 1.8 39 370 962 168 , 2.8 '314 16 1,025 68 20 2.1 92 31 14 384 65 3.6 420 12 11 97 38 58 413 92 04 570 1. Spring at Savage. 2. Well of Christopher Schmidt at Belle Plaine. April, 1897. 3. Chicago, St. Paul, Minneapolis and Omaha Railway well at Belle Plaine. June, 1900. 4. Gran Milling Company well at Belle Plaine. March, 1906. 5. Chicago, St. Paul, Minneapolis and Omaha Railway well at Savage. June, 1901. 6. Well at Jacob Ries's Bottling Works at Shakopee. June, 1897. 7. Well of George A. Cole at Jordan. June, 1897. 8. Chicago, St. Paul, Minneapolis and Omaha Railway well at Merriam Junction. Analyses 3, 4, 5, and 8 were furnished by G. M. Davidson, chemist Chicago and Northwestern Railway Company. Analyses 2 and 7 were furnished by Edgar & Mariner. Analysis was furnished by Jacob Ries. SIBLEY COUNTY. By C. W. Hall and M. L. Fuller. SURFACE FEATURES. Sibley County has an average elevation of about 1,000 feet above sea level, or fully 200 feet above the broad valley of Minnesota River, 342 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. which borders it on the east. Though its surface is generally only gently undulating, locally it is rolling, and the depressions are occu- pied by lakes. However, no prominent moraines are found in the county. Its southern and eastern portions are drained by Rush River and other tributaries of the Minnesota, whose valleys near their mouths attain a depth of 150 to 200 feet. SURFACE DEPOSITS. Crystalline rocks are found at a few points in the valley of the Minnesota, but the rest of the county is covered by a thick mantle of surface deposits through which very few wells penetrate. Alluvium is found in the valleys of Minnesota River and its largest tributaries. Its thickness varies, probably averaging less than 50 feet. The depth to which wells are sunk at points along the valley before reaching rock indicate the presence of a deep preglacial channel, which is seemingly west of the present stream where it borders Carver County and mainly east of it along Sibley County. The alluvium contains moderate quantities of water, but owing to the presence of considerable amounts of silt it is not given up as in coarser deposits. Supplies sufficient for ordinary purposes may be secured, but volumes adequate for large industries or public sup- plies are not to be expected. Along the Minnesota at heights of 75 to 150 feet above the stream there is a series of terraces, cut principally into the bowlder clay of the glacial drift. The lower terraces are covered by only a thin layer of ancient alluvium, but on the higher ones this sand and gravel deposit is at many points 20 to 30 feet thick. The terrace deposits are found chiefly near the northeastern and southeastern corners of the county in tracts about one-fourth mile wide. They contain water in moderate amounts except near the outer edge of the ter- races, from which it is drained into the adjacent valleys. Except for the few outcrops near the Minnesota, Sibley County is wholly covered by drift. From exposures along the valley and the sections revealed by wells, its thickness in the eastern part of the county is known to be about 250 feet. Elsewhere the thickness is even greater, as shown by well sections, reaching 397 feet near the northeastern corner of the county, 275 feet at Gibbon, and 400 feet at Winthrop. (See the sections given below.) The drift as a whole consists mainly of bowlder clay, some of the wells reporting this material (with almost no sand or gravel seams) for the entire depth to the rock. Below the surface soil is found the characteristic yellow oxidized clay to a depth of 12 or 15 feet, and below this, in most localities, a great thickness of grayish blue clay derived largely from Cretaceous material brought in from the northwest, and including some carbonized wood or lignite. At one SIBLEY COUNTY. 343 point very near the northeastern corner of the county there was found a small amount of red clay, representing material brought from the northeast. Until the last few years the water supplies throughout Sibley County have been obtained mainly from shallow surface wells, but in recent years many deep wells have been bored, the present number probably being not less than 200. It has been found, however, that, notwithstanding the great thickness of the drift, sandy or gravelly layers are relatively uncommon, and it is often necessary to drill several hundred feet in search of water supplies. In some wells no water zones are encountered in the drift, but a thin porous stratum is generally found at the contact of the drift with the underlying rock. By far the greater number of wells can obtain supplies sufficient for domestic, farm, and industrial purposes, and even for public supplies, without penetrating the rock. ROCK FORMATIONS. The Jordan sandstone probably occurs in the southeastern extrem- ity of the county but is absent elsewhere. The St. Lawrence formation consists of thin layers of pink mag- nesian limestone alternating with beds of shale that are in many parts characterized by a green color. It outcrops at a number of points in the Minnesota Valley north of Henderson and underlies a belt several miles wide parallel to the river. It gives rise, along the stream mentioned, to a large number of springs, many of which are used in the rapidly developing dairy industry. Six streams fed by springs are reported in T. 113 N., R. 26 W., and one in sec. 2, T. 112 N., R. 26 W. Some of the springs are said to form streams large enough to furnish water power. Beneath the uplands the St. Lawrence, though probably containing moderate amounts of water in its bedding planes, joints, etc., is not likely to yield more than the over- lying drift and is not to be considered as a promising source of supply. The Dresbach sandstone and underlying shales have not been observed in Sibley County, but were encountered below the St. Law- rence formation in the deep well at Henderson and probably lie immediately beneath the drift in the central part of the county. The successive beds of sandstones, which are separated by shale, are good water bearers and will yield abundant supplies to deep wells both in the valleys and uplands, but the water will rise to the surface in the Minnesota Valley only. Outcrops along Minnesota River make it clear that 50 feet or more of red conglomerate and at least 250 feet of red or gray quartzite intervene between the rocks just described and the granite. They are of little or no value as a source of water supply. 344 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. The western part of the county is underlain by granitic rocks which yield no water except near the top, where they may be fissured or decayed. To supplement the above statements in regard to the character and distribution of the formations found in this count}^ the following logs of deep wells with their hypothetical interpretations are here given : Section at Henderson. [City well sunk in 1890. Altitude of the surface is about 7.50 feet above sea level. Authority, H. P. Pfeirler.] Alluvium: Gravel Glacial drift : Sand, gravel, and bowlders St. Lawrence formation: Gray and yellow limestone Pink limestone Green clay and limestone White water-bearing sand Red limestone Gray limestones and sandstones Red limestone White sandstone Coarse white sand Coarse yellow sand Green sandstone and limestone Coarse sandstone Fine-grained yellow sandstone Thick- ness. Depth. Feet. Feet. 20 20 25 45 10 55 9 64 250 314 13 327 117 444 30 474 10 484 35 519 55 574 35 609 15 624 20 644 62 706 Section at Green Isle. [Minneapolis and St. Louis Railroad well. Authority, chief engineer Minneapolis and St. Louis Railroad Company.] Thick- ness. Depth. Artificial filling Glacial drift: Blue clay Sand and gravel (water) Dresbach sandstone (?) and underlying beds Soft white sandstone (water) Red clay or shale Blue shale Hard white sandstone Feet. Feet. 77 180 24 204 25 229 15 244 15 259 87 346 Section at Winthro'p. [Well drilled for the Minneapolis and St. Louis Railroad Company in 1903. The surface altitude is about 1,018 feet above sea level. Authority, H. G. Kelly, chief engineer Minneapolis and St. Louis Railroad Company.] Clay Fine-grained sand (water). Clay (glacial) Coarse sand White sand Red shale Red shale with white sand Granite (entered) Thick- ness. Depth. Feet. Feet. 212 212 8 220 150 370 21 391 8 399 9 408 4 412 2 414 SIBLEY COUNTY. 345 UNDERGROUND WATER CONDITIONS. Yield of water. — Near the surface the drift contains considerable water but the yield is not generally large and the supply is frequently affected by drought. The bulk of the drift is relatively barren of water-bearing beds, as has already been explained, but at or near the base one or more beds usually exist which will yield generously. In the eastern portion of the county the rock formations will furnish large supplies, but farther west these are absent. The 8-inch city artesian well at Henderson is reported to flow 300 gallons a minute; the 10-inch railway well at Green Isle has been pumped at the rate of 150 gallons a minute; and the 10-inch village well at Winthrop has been tested at the rate of 75 gallons a minute. Head of the water. — On the uplands flowing wells can not be obtained from the deeper beds, but in the Minnesota Valley the water from the sandstones will generally rise above the surface. The following table gives the head of the water from the deeper drift and sandstone zones at various localities in this county or adjacent to it: Depth and altitude of the head of the water at localities in and near Sibley County. Distance of water level Head Locality. above above ( + )or sea level. bek>w(— ) surface. Feet. Feet. - 10 1,055 - 13 1,045 - 24 995 - 90 905 - 90 909 — 80 960 — 80 —121 964 897 + 60 + 18 810 778 WATER SUPPLIES FOR CITIES AND VILLAGES. Winthrop. — The village of Winthrop has a system of public water- works supplied from a 10-inch well which is 239 feet deep. As is shown by the stratigraphic section of this well given on page 344, the Archean granite was struck 412 feet below the surface. Most of the inhabitants use water from private wells. Henderson. — The section and other data in regard to the city well at Henderson are given on pages 343-344. The system of waterworks is used chiefly for fire protection, the domestic supply being taken principally from other wells. Gibbon. — The village of Gibbon is provided with a system of water- works which draws from a well 210 feet deep, but private wells are relied on for domestic supplies. 346 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. SUMMARY. At nearly all points in this county beds of sand or sandstone which will yield adequate supplies occur within several hundred feet of the surface. The water from these depths will generally be found to be more satisfactory for domestic and boiler uses than that from shallow sources. It is under sufficient pressure to give rise to flows in the Minnesota Valley, but will everywhere stand below the upland level. In the western part of the county granitic rock will be encountered at depths of several hundred feet. It should not be penetrated, as it is not water-bearing. STEELE COUNTY. By C. W. Hall and M. L. Fuller. SURFACE FEATURES. The upland surface of Steele County, which stands between 1,100 and 1,200 feet above sea level, is interrupted only by two morainal belts and by the shallow valleys of Straight River and its tributaries. Of the morainal belts the more eastern is the narrower, ranging from one-half mile to 5 miles in width and generally standing not more than 100 feet above the surrounding plateau surface. It crosses the county from north to south a little west of its eastern border and is characterized by groups of irregular hills and basins. The other belt, which is somewhat lower, is seen along the western edge of the county, south of the Chicago and Northwestern Railway, where a width of about 4 miles falls within the county with an equal or greater width in Waseca County to the west. The intermediate area, though slightly undulating, is relatively flat and is characterized in places by lakes and swampy tracts of considerable size, some of which have been artificially drained. Straight River rises in the southern part of the count) 7 and flows northward between the moraines, eventually joining Cannon River. Throughout most of its course its valley is shallow, but near the border of Rice County the valley deepens to about 100 feet. SURFACE DEPOSITS. The glacial drift, which everywhere mantles the surface, varies in depth from a few feet in the valle}" of Straight River to 50 or 100 feet along its edges, 100 to 150 feet in the uplands of the central part of the county, and 150 to 200 feet in the morainal areas of the eastern and western parts of the county. Near Deerfield a number of wells have encountered a bluish-black clay underlain by gravel and sand and some lignite, the material resembling the deposits which have been referred to the Cretaceous STEELE COUNTY. 347 in other counties in southeastern Minnesota.® While there is no definite evidence as to the age of these beds, a late suggestion by Leverett and Sardeson is that they belong to a pre-Kansan deposit of the glacial drift. Practically no water occurs in the clays, but the sands beneath generally contain considerable amounts. PALEOZOIC FORMATIONS. The Devonian sandstone is a fine-grained gray to white sandstone with a few shaly limestone layers. It underlies a small area near the southeast corner of the county and probably reaches as far north as Owatonna, where a sandstone is known to rest upon the shaly limestone strata that are regarded as Galena. The formation generally yields water in rather large amounts and in some places under considerable artesian pressure. The Galena limestone, Decorah shale, and Platteville limestone doubtless underlie the entire county, and from well records and other evidence they appear to have an aggregate thickness of nearly 200 feet. The uppermost formation is at man}" places broken and fissured and contains water under more or less artesian pressure. In some wells abundant supplies are obtained, but in others the yield is not satisfactory. The St. Peter sandstone underlies the Platteville limestone through- out the entire county and is reached at 300 feet or more below the surface. It generally contains abundant water and yields strong supplies. Below the St. Peter the following water-bearing beds occur: List of water-bearing beds lovjer than the St. Peter sandstone. Approxi- mate thick- ness. Approxi- mate depth below the bottom of the St. Peter. Feet. 10 to 20 80 90 200 Feet. 50 150 500 650 All these formations contain large quantities of water under suffi- cient pressure to cause them to enter the wells freely. They may be expected to furnish supplementary supplies of importance if the St. Peter fails through overdraft or otherwise. a Harrington, M. AY., Final Rept. Geol. and Nat. Hist. Survey Minnesota, vol. 1, 1882, p. 398. 348 UNDERGROUND WATERS OE SOUTHERN MINNESOTA. The following log of the well drilled for the city of Owatonna in 1878 gives a section of the strata to the bottom of the St. Peter: Well section at Owatonna. Thick- ness. Depth. Glacial drift: Gravel and sand Blue, stony clay Gravel and bowlders with much water Devonian(?): White quartz sand Soft limestone, decayed Yellow clay, making the water very yellow Hard white sandstone Galena, Decorah, and Platteville formations (?): Blue compact limestone Blue sandstone, " like grindstone grit " Blue shale Light-gray shale Shale, "full of specks of iron pyrites, very hard to drill" Blue shale Light-gray shale Blue clay Hard yellow rock Blue clay and shale Lead-colored clay, making the water dark blue Hard yellow rock Blue arenaceous shale Blue shale A cherty layer Blue limestone St. Peter sandstone: White sandstone Similar to the last, but very hard; thought to contain iron pyrites White sandstone Feet. 20 14 Feet. •jo 34 39 60 62 63 98 118 128 138 148 151 171 176 188 190 240 243 250 253 261 262 290 370 378 387 a TJpham, Warren, Final Rept. Geol. and Nat. Hist. Survey Minnesota, vol. 1, 1SS2, pp. 39S-399. The interpretation here given is by C. W. Hall and is somewhat different from that given by Mr. Upham. UNDERGROUND WATER CONDITIONS. Wells. — Except along the valley of Straight River the drift is everywhere of considerable thickness, and wells sunk to sandy or gravelly layers 10 to 40 feet below the surface are common. In general the shallow supplies are less satisfactory than the deeper ones, and have the disadvantages of being liable to pollution and of failing in times of drought. For these reasons many relatively deep wells have been drilled. In the valley of Straight River, as at Owatonna, some of the wells penetrate to the underlying sandstones. Head of the water. — Although Steele County contains some of the highest land in the southeastern portion of the State, there are many flowing wells within its area. These occur in the shallow valleys through the central part of the county and obtain their head from the high morainic belts on either side. The area hi which flows can be obtained is shown in Plate IV. WATER SUPPLIES FOR CITIES AND VILLAGES. Owatonna. — The public supply at Owatonna is taken from five wells 95 feet deep, and one 6-10 feet deep. Shallow wells are the common source for private water supplies, but in recent years drilling has been STEELE COUNTY. 349 carried in a number of wells to depths of 200 to 250 feet. Several flowing wells are reported, ranging in depth to 250 feet. Blooming Prairie. — The village of Blooming Prairie has a system of public waterworks supplied from a drilled well 245 feet deep, which ends in Galena or Platteville limestone. EEenddle. — More than one-half of the people of Ellendale depend on the public supply which is obtained from a well 212 feet deep. SUMMARY AND ANALYSES. Adequate supplies can usually be obtained from the glacial drift or creviced portions of the Galena limestone, but if a larger yield is required than these formations will furnish drilling should be con- tinued to the sandstones which everywhere underlie the county and which will provide generous and permanent supplies. Mineral analyses of water in Steele County. [Analyses in parts per million.] 3. 5. 6. 7. 28 17 19 18 56 42 123 15 15 48 12 16 35 277 248 593 3.3 2 49 1.8 .9 29 392 348 594 Depth feet. Silica (Si0 2 ) Calcium (Ca) Magnesium (Mg) Sodium and potassium (Xa+K) Bicarbonate radicle (HC0 3 ) Sulphate radicle (SO*) Chlorine (CI) 10 69 26 6.2 339 3.9 6.7 Total solids I 290 17 233 23 5.5 294(?) 33 216 24 5.8 391 Tr. 1.7 678 33 237 22 4.8 - -^y ■ ' 2.1 304(?) 35 11 98 36 27 481 31 18 459 12. Depth feet. Silica (Si0 2 ) Calcium (Ca) Magnesium (Mg) Sodium and potassium (Na+K) Bicarbonate radicle (HCO3) .• Sulphate radicle (S0 4 ) Chlorine (CI) Total solids 28 29 102 71 32 31 16 16 399 396 61 11 20 19 429 426 127 40 21 356 233 592 122 39 37 353 219 19 609 122 38 34 350 238 605 103 34 13 375 88 20 453 132 42 27 452 128 42 608 640 16 96 35 5 467 2.9 5.5 640 9.9 97 26 8 496 6.3 6.1 1. Straight River at Owatonna. April, 1889. 2. Spring at Owatonna. January, 1905. 3. Spring at Owatonna. January, 1905. 4. Spring at Owatonna. January, 1905. 5. Morford Spring at Owatonna." 1875. 6. Flowing Spring at Owatonna. 1875. 7. Chicago and Northwestern Railway well at Owatonna. January, 1889. 8. Chicago and Northwestern Railway well at Owatonna. March, 1890. 9. Chicago, Milwaukee and St. Paul Railway well at Owatonna. August, 1890. 10. Chicago, Milwaukee and St. Paul Railway well at Owatonna. December, 1899. 11. Chicago, Milwaukee and St. Paul Railway well at Owatonna. March, 1900. 12. Chicago, Milwaukee and St. Paul Railway well at Owatonna. April, 1900. 13. Chicago, Milwaukee and St. Paul Railway well at Owatonna. July, 1900. 14. Chicago, Milwaukee and St. Paul Railway well at Blooming Prairie. August, 1890. 15. Chicago, Milwaukee and St. Paul Railway well at Blooming Prairie. December, 1893. 16. City well at Owatonna. 1890. 17. City well at Owatonna. 1891. Analyses 2, 3, and 4 were made by II. C. Carel, and analyses 5 and 6 by Gustave Bode. Analyses 1 and 7 were furnished by G. M. Davidson, chemist Chicago and Northwestern Railway Company; analyses 8 to 17 by G. N. Prentiss, chemist Chicago, Milwaukee and St. Paul Railway Company. 350 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. SWIFT COUNTY By O. E. Meinzer. SUE FACE FEATURES. Most of Swift County consists of a very gently undulating prairie, characterized by marshy areas through which sluggish streams meander, but containing few definite drainage channels and few well- defined lakes. Near the northeastern and northwestern corners, however, the topography is more morainic and there are numerous lakes. A small morainic area also occurs in the vicinity of Danvers near the center of the county. Two rivers flow southward and empty into the Minnesota — the Pomme de Terre in the western and the Chippewa in the central part. The valleys of both are small where they enter the county, but become wider and deeper as they pro- gress. Their few tributaries have not yet dissected the prairie sur- face to an important extent. The Minnesota Valley borders the county for a few miles on the southwest. SURFACE DEPOSITS. Description. — The surface deposits include ordinary glacial drift, glacial outwash materials, and recently deposited alluvium. The drift covers the entire county and constitutes by far the greatest part of the surface deposits. The materials washed out from the ice sheet were in large measure laid down along the principal streams, forming extensive sheets of stratified sand and gravel. Alluvial deposits made by the streams since the last glacial epoch are of trivial importance. The thickness of the surface deposits ranges from less than 100 to more than 300 feet and averages somewhat more than 200 feet. In general it is least in the southwestern part and increases toward the northeast. At Appleton underlying formations have been struck at a depth of 65 feet, and in the northwestern portion of the county at 185 to 240 feet, but in the morainic area of the northeast drilling has gone to depths of at least 300 feet without reaching the bottom of the drift. Yield of water. — Wherever the outwash materials are found at the surface they provide relatively copious supplies from depths commonly ranging between 10 and 40 feet. The sand and gravel deposits inter- mingled with the bowlder clay of the glacial drift are generally satu- rated with water, and in nearly every locality beds of this type are sufficiently thick and coarse to afford supplies adequate for ordinary purposes. As a rule the deepest beds yield the most water and are least affected by drought. The two city wells at Benson are 6 and 8 inches in diameter and end in a gravel bed in the drift at a depth of 167 feet. Pumping at the rate of 160 gallons a minute from the SWIFT COUNTY. 351 two wells lowers the water 25 feet, but they will yield at this rate for an indefinite period. Head of the water. — Throughout most of Swift County, especially the central and eastern portions, the water from the drift beds comes nearly to the surface. There are flowing wells in a number of locali- ties and they could without doubt be obtained on the lowest places adjoining Chippewa River and its tributaries, and probably in other depressed areas. Flows are reported (1) in the vicinity of Swift Falls, on East Branch of Chippewa River; (2) on the lowest ground in the vicinity of Lake Hassel, north of Benson; and (3) along Shako- pee Creek. They are also found along Chippewa River south of this county. In the city wells at Benson the water rises within 13 feet of the surface, which is virtually to the level of the river; at Danvers it is said to stand only 2 feet below the surface, but no flows are reported; and at Clontarf and Murdock it is reported to rise within 6 to 12 feet of the surface. The head is obtained largely from the high morainic belt northeast of this county. Quality of the water. — The water from the lower portion of the gla- cial drift is softer than that from the upper. The latter contains much calcium and magnesium (the constituents that produce hardness), and these elements are associated to a large extent with the sulphate radicle and are deposited as hard scale in boilers. The deepest water, on the contrary, contains less calcium and magnesium, and only small quantities of sulphate radicle, and hence is better for boiler purposes. In the accompanying table compare analyses 1 to 4 with analysis 5. Though only one analysis (No. 5) is given of water from the lower portion of the drift, this one is known to be representative. CRETACEOUS SYSTEM. Description. — Cretaceous sedimentary rocks probably underlie most of this county, but in some localities, especially near Minnesota River, they are absent. But little deep drilling has been done and nearly all the wells end in the surface deposits. In the unsuccessful well drilled for the city of Benson glacial drift extended to a depth of at least 170 feet and the granitic rocks were entered at about 400 feet. Between these levels some shale was reported, but no reliable section is at hand. Shale was also reported in several wells in the western part of the county, the sections of two of which are given below. As shale has been encountered in all the counties bordering on Swift, it is safe to assume that it occurs generally in this county, but the Cretaceous must everywhere be thin, perhaps rarely reaching 100 feet in thickness. Although it consists chiefly of soft gray-blue shale (" soapstone ") , there are probably also beds of sand or sand- stone in some localities. 352 UNDERGROUND WATERS OF SOUTHERN MINNESOTA. The following is the approximate section of an unsuccessful well on the farm of Philip Weise, sec. 28, T. 122 N., R. 42 W.: Section in western Swift County (Weise well). [Authority, Mr. Lawler, driller, Morris.] Glacial drift: Y ellow bowlder clay Blue bowlder day Cretaceous: Shale or "soapstone". A.rchean: Granite Thick- aess. Feet. 30 170 50 Depth. Feet. 30 200 250 The following is the approximate section of a well on the farm of Philip Schreck, NE. £ sec 8, T. 121 N., R. 43 W. Section in western Swift County (Schreck well). [Authority. Lewis Johnson, driller, Appleton.] Thick- ,, aess. De P th ' Glacial drift: Soil and yellow bowlder clay Quicksand B lue bowlder elay Cretaceous: Shale (a good yield of rather soft water at the depth of '-MS feet). Feet. 30 to 145 63 I\ O F SOUTHERN MINNESOTA SHOWING THICKNESS AND CHARACTER OF SURFACE DEPOSITS LEGEND U. S. GEOLOGICAL SURVEY GEORGE OTIS SMITH, DIRECTOR WATER-SUPPLY PAPER 256 PLATE III LEGEND U. S. GEOLOGICAL SURVEY GEORGE OTIS SMITH, DIRECTOR WATER-SUPPLY PAPER 256 PLATE IV '*9W R.4-8 LEGEND ■J r.