gal Survey ILLINOIS STATE QEOLOQICAL SURVEY 3 3051 00000 1945 Digitized by the Internet Archive in 2012 with funding from University of Illinois Urbana-Champaign http://archive.org/details/geologymineralre57wanl STATE OF ILLINOIS DEPARTMENT OF REGISTRATION AND EDUCATION DIVISION OF THE STATE GEOLOGICAL SURVEY M. M. LEIGHTON. Chief BULLETIN NO. 57 GEOLOGY AND MINERAL RESOURCES OF THE ALEXIS QUADRANGLE BY HAROLD R. WANLESS PRINTED BY AUTHORITY OF THE STATE OF ILLINOIS URBANA, ILLINOIS 1929 ILLINOIS GEOLOGICAL SURVEY LIBRARY STATE OF ILLINOIS DEPARTMENT OF REGISTRATION AND EDUCATION M. F. Walsh, Director BOARD OF NATURAL RESOURCES AND CONSERVATION M. F. Walsh, Chairman Edson S. Bastin, Geology William A. Noyes, Chemistry John W. Alvord, Engineering William Trelease, Biology Henry C. Cowles, Botany Charles M. Thompson, Representing the President of the University of Illinois STATE GEOLOGICAL SURVEY DIVISION M. M. Leighton, Chief Jeffersons Printing & Stationery Co. Springfield, Illinois 1929 Letter of Transmittal State Geological Survey Division, August 29, 1929. M. F. Walsh, Director, and Members of the Board of Natural Resources and Conservation, Gentlemen : I have the honor of transmitting herewith a report, on the Geology and Mineral Resources of the Alexis Quadrangle, by Dr. Harold R. Wanless, which is to be printed as Bulletin No. 57 of our series. This report is based upon detailed field studies which were undertaken to as- certain the mineral resources of the area in coal, clay and shale, limestone, sandstone, sand and gravel, molding sand, oil and gas, underground water supplies, and other possible resources, and to secure stratigraphic and struc- tural information important to an understanding of the geology of this portion of the State. The various mineral resources, of which coal, clay and shale, and underground water supplies were found to be the most important, are herein discussed as to their occurrence, character, relative importance, present development, and possibilities of future development. In addition to the needed detail that is incorporated in this report, there are in the files of the Geological Survey certain other data and collections of materials available to those interested in special economic and scientific problems. Editorial preparation of the author's manuscript and maps, from the standpoint of geologic science, has been made by Dr. George E. Ekblaw, Geologic Editor. Very respectfully, Morris M. Leighton, Chief. Contents Page Chapter I 15 Location and extent 15 Purpose of the report 15 Acknowledgments 15 Fundamental geologic processes 16 Introductory statement 16 Work of running water 17 Work of ground water 17 Work of stagnant water 18 Work of wind 19 Glaciation 19 Marine sedimentation 20 Diastrophism 21 Weathering 21 Chapter II Physiography 23 Relief and drainage 23 Geography 26 Distribution of population 20 Industries 26 Transportation 17 Chapter III — Descriptive geology 29 Introduction 29 Cambrian system 29 Introduction 29 Croixan series 29 Ordovician system 31 Introduction 31 Prairie du Chien series 31 Mohawkian series $3 St. Peter formation 33 Glenwood formation 34 Platteville formation 36 Decorah formation % 36 Galena formation 37 Cincinnatian series 37 Maquoketa formation 37 Silurian system 38 Introduction 38 Niagaran series 58 Devonian system : V> Introduction J9 7 Chapter III — continued Page Senecan series - 40 Wapsipinicon and Cedar Valley formations 40 Mississippian system 41 Introduction 41 Kinderhook series 41 Sweetland Creek formation 42 Hannibal formation 43 Osage series 45 Burlington formation 45 Pennsylvania!! system 46 Introduction 46 Subdivisions 47 Pottsville formation 50 Suite I — Strata below the "Stigmarian" sandstone 51 Stratigraphic relations 53 Paleontology and correlation 55 Suite II — Strata between the base of the "Stigmarian" sandstone and the unconformity above the Rock Island (No. 1) coal 55 Lithologic characteristics 55 "Stigmarian" sandstone 56 Underclay of the Rock Island (No. 1) coal 57 Rock Island (Xo. 1) coal 57 Black laminated shale 58 Limestone cap-rock 61 Shaly limestone ("Blue rock") 62 Shale 62 Stratigraphic relations 62 Correlation 63 Suite III — Strata between the unconformity above the Rock Island (No. 1) coal and the top of the Gilchrist shale 64 Lithologic characteristics 65 Basal sandstone 70 Gilchrist shale 73 Stratigraphic relations 74 Paleontology and correlation 76 Suite IV 77 Undifferentiated Pottsville strata 77 Basal conglomerate 77 Conglomeratic sandstone 77 Carbondale formation 78 Suite IV — Strata between the top of the Gilchrist shale and the base of the Pleasantview sandstone 80 Lithologic characteristics . . ■ 80 Sandstone 80 Underclay 83 Colchester (No. 2) coal 83 Soft gray shale above coal 84 Black laminated shale 84 Gray shale containing concretions 86 Dark fossiliferous limestone 86 Gray shale 87 8 Chapter III — concluded Page Stratigraphic relations 88 Correlation 89 Suite V— Pleasantview sandstone and overlying strata 89 Lithologic characteristics 90 Pleasantview sandstone 90 Stratigraphic relations 90 Correlation 90 Post-Pennsylvanian pre-Pleistocene deposits 91 Preglacial surface 91 Pleistocene system 92 Introduction 92 Kansan series 94 Yarmouth series 96 Illinoian series 98 Sangamon series 103 Iowan and Peorian series 104 Recent system 106 Post glacial deposits 106 Chapter IV — Structural geology 107 Introductory statement 107 Data used in making structural maps of the Alexis quadrangle 107 Structural features 109 Top of Dresbach formation 109 Base of St. Peter formation, top of St. Peter formation, top of Galena formation, and top of Maquoketa formation 109 Top of Niagaran series and top of Devonian system 109 Pennsylvanian structures Ill Structure of the Rock Island (No. 1) coal Ill Structure of the Colchester (No. 2) coal 112 Minor structural features 113 Chapter V — Geologic history 115 Introduction 115 Pre-Paleozoic eras 116 Paleozoic era 116 Cambrian period 116 Ordovician period 117 Early Ordovician epoch 117 Middle Ordovician epoch 118 Late Ordovician epoch 119 Silurian period 119 Alexandrian epoch 119 Niagaran epoch 119 Devonian period 119 Missisippian period 120 Pennsylvanian period 121 Pottsville epoch 121 Carbondale epoch 123 Post-Pennsylvanian pre-Pleistocene interval 124 Pleistocene period 125 Kansan epoch 126 Yarmouth epoch 126 9 Chapter V — concluded Page Illinoian epoch 127 Sangamon epoch 128 Iowan epoch 128 Peorian epoch 129 Wisconsin epoch 130 Recent period 130 Chapter VI — Economic geology 133 Mineral resources 133 Coal 133 Rock Island (No. 1) coal 7 133 General statement 133 Unexplored areas probably underlain by Rock Island (Xo. 1) coal. 137 Areas near transportation 137 Areas remote from transportation 138 Coal beds below Rock Island (Xo. 1) coal 138 Coal beds between Rock Island (Xo. 1) coal and Colchester (Xo. 2) coal 140 Colchester (Xo. 2) coal 140 Coals of uncertain stratigraphic position 140 Mining methods 140 Shale and clay 141 Gilchrist shale 141 Clays 141 Ceramic plants 142 Hydraulic Press Brick Company 142 X"orthwestern Clay Manuf acturing Company 143 Monmouth Clay Manufacturing Company 143 Sand and gravel 146 Building stone 146 Limestone 147 Water resources 148 Possible water-bearing formations 148 Cambrian system 148 Ordovician system 148 Silurian system 148 Devonian system 148 Mississippian system 148 Pennsylvanian system 149 Pleistocene system 149 City water supplies .' 149 Farm wells 150 Wells deriving water from rock 150 Wells deriving water from glacial drift 150 Springs 151 Surface water 151 Soils 151 Introduction 151 Soils classified according to parent material 152 Soils on loess 152 Soils on glacial drift and slope wash 152 Soils on alluvial deposits 152 Soils classified according to conditions of development 153 10 Chapter VI — concluded Page Possibilities of oil and gas production 153 Introductory statement 153 Possible oil-bearing formations 153 Favorable structural areas 154 Previous oil-tests 154 Areas most favorable for testing 155 Appendix A — Pennsylvanian fossils 157 Appendix B Part I — Measured geologic sections of Rock Island (No. 1) coal and associated strata 164 Part II — Measured geologic sections of Colchester (No. 2) coal and associated strata 171 Part III— Mine data 173 Appendix C — Well logs 177 Deep wells, detailed records 177 Farm wells 202 Shallow wells and wells with incomplete records 208 Index 218 11 Illustrations Plate Page I Surficial and economic geology of the Alexis quadrangle ( In pocket) II Xorth-south cross-section of the Alexis quadrangle 50 III Graphic representations of Rock Island (No. 1) coal and associated strata.... 58 IV Bedrock surface of the Alexis quadrangle (In pocket) V Graphic logs of deep wells in and near the Alexis quadrangle (In pocket) VI Graphic logs of shallow wells in and near the Alexis quadrangle (In pocket) Figure Page 1. Index map showing the location of the Alexis quadrangle 14 An eight-foot granite boulder from the glacial drift 19 View of Pope Creek, showing steep south slope and more open north slope of the valley walls 23 An early stage in the development of gullies on deforested slopes of glacial drift 24 "Bad-land" topography developed in Pennsylvanian shale 24 A terrace remnant of a former alluvial plain in a tributary valley 25 View of alluvial plain along Pope Creek 27 Photomicrograph of St. Peter sand 34 Photomicrograph of Glenwood sandstone 35 Workable bed of coal in Suite I of the Pottsville formation 50 Inclined sandstone beds of Suite I. exposed in a small gully 54 A resistant ledge of "Stigmarian" sandstone 57 Diagrammatic sketch representing variation in Rock Island (No. 1) coal and associated strata 58 Limestone cap-rock of the Rock Island (No. 1) coal 59 Limestone strata overlying the Rock Island (Xo. 1) coal in Spring Grove Township 60 Limestone strata overlying the Rock Island (No. 1) coal in Greene Township. 61 Pottsville strata containing a five-inch bed of weathered coal 66 Graphic log of a coal-test boring 69 Basal sandstone of Suite III or Suite IV rilling a channel cut into Suite II. Pottsville formation 70 Exposure of strata showing contact between Suites III and IV, Pottsville formation 71 A bed of shell marl overlying a thin coal seam, lower part of Suite III 72 Sandstone containing conglomeratic layers, exposed in an old quarry 78 Graphic representation of outcrops of Suite IV in north and south parts of quadrangle 79 Graphic representation of seven outcrops of Suite IV showing variations in altitude, succession, and thickness of the members 81 Basal sandstone of Suite IV, exposed along Pope Creek 82 Cross-bedded basal sandstone of Suite IV 83 Colchester (No. 2) coal exposed in wall of gully 84 12 Page 28. Black laminated shale overlying Colchester (No. 2) coal, Greene Township 85 29. Hard, black, laminated shale overlying Colchester (No. 2) coal, exposed in a creek bed, Suez Township 85 30. Large, calcareous concretions in the black, laminated shale overlying Colchester (No. 2) coal 87 31. Fossiliferous limestone concretions one foot above the black, laminated shale overlying the Colchester ( No. 2) coal 87 32. Natural cross-section of a septarian concretion four feet in diameter 88 33. Unconformable contact between glacial drift and shale of the Pennsylvanian system 92 34. Yarmouth sand exposed in section 12, Sumner Township 97 35. Detail of Yarmouth sand showing secondary color banding 97 36. Typical exposure of Pleistocene deposits 101 37. Peorian loess overlying Illinoian till 102 38. Structure maps of four Paleozoic horizons 108 39. Structure maps of two Paleozoic horizons 110 40. Structure map of Rock Island (No. 1) coal in north part of the Alexis quadrangle 112 41. Structure map of Rock Island (No. 1) and Colchester (No. 2) coals in south- east part of the Alexis quadrangle 113 42. Minor faulting in lower Pennsylvanian sandstone 114 43. A small overturned fold in the Gilchrist shale 114 44. Map showing extent of glaciation in North America 125 45. Map showing areas from which Rock Island (No. 1) coal has # been mined.... 134 46. Rock Island (No. 1) coal exposed in old drift mine 134 47. Graphic representations of Rock Island (No. 1) coal 135 48. Gilchrist shale in Hydraulic Press Brick Company's pit at Shale City 142 49-50. General view of plant of the Hydraulic Press Brick Company at Shale City. 144 51-52. General view of plant of the Northwestern Clay Manufacturing Company at Griffin 145 53. Face of an old quarry in shaly limestone 147 Tables Page 1. Stratigraphic classification of rocks facing 30 2. Analysis of mine samples of Rock Island (No. 1) coal from the Alexis quad- rangle and vicinity 135 3. Mineral analyses of water from wells in the Alexis quadrangle facing 148 13 14 ALEXIS QUADRANGLE r;T~ MESS 'STEPHENSON | WINNEBAGO | ^^y , UAKe i ° QLE i r~ l Fig. 1. Index map of Illinois showing the location of the Alexis quadrangle (No. 3) with reference to the Illinois coal field (outlined by stippled boundary) and to other nearby quadrangles which have been surveyed geologically: (1) Edgington ; (2) Milan; (4) Monmouth; (5) Galesburg; (6) La Harpe; (7) Good Hope; (8) Avon; (9) Canton. GEOLOGY AND MINERAL RESOURCES OF THE ALEXIS QUADRANGLE By Harold R. Wanless CHAPTER I Location and Extent The Alexis quadrangle is located in the northwestern part of Illinois, about fifteen miles south of Rock Island. Approximately the north three- fourths of the quadrangle is in Mercer County, and the south quarter is in Warren County. (See fig. 1.) It is bounded on the east and west respec- tively by the meridians of 90° 30' and 90° 45' W. and on the south and north respectively by the parallels of 41° 00' and 41° 15' N. It is about 17 miles long and 13 miles wide, and its total area is about 225 square miles. Purpose of the Report This report is published in order to place geological information regard- ing all of the mineral resources of the area in the hands of those who are interested in either or both the economic or educational possibilities of the area. Coal underlies extensive portions of the Alexis quadrangle ; some clay and shale is being utilized for brick and tile, and other deposits present are suitable for ceramic uses ; ground-water supplies for both domestic and in- dustrial uses are being continually sought ; and the productive soils constitute a mineral' resource of fundamental importance. The geological history of the area also is of more than usual interest to teachers, students, and residents. Acknowledgments Mr. R. E. Grim and Mr. A. W. Waldo served as field assistants during: the summers of 1925 and 1926, respectively, when the field studies in the Alexis quadrangle were made. The author is indebted to various members of the Illinois State Geolog- ical Survey for contributory suggestions and for criticism of the manuscript, especially to Dr. M. M. Leighton, Chief, in regard to the Pleistocene de- posits, to Dr. G. H. Cady and to Dr. H. E. Culver, formerly of the Survey, in regard to the Pennsylvanian formations, and to Mr. L. E. Workman in regard to the older formations, and to Dr. G. E. Ekblaw for geologic editing of the entire report. Dr. R. S. Poor and Mr. L. E. Workman supplied infor- 15 16 ALEXIS QUADRANGLE mation based on their respective studies in the Galesburg and Monmouth quadrangles, both adjacent to the Alexis quadrangle. Incidental assistance has been rendered by many others. Dr. A. C. Noe, of the University of Chicago, collected plant fossils from this area and identified all the Pennsylvanian plants listed in this report. The late Pro- fessor Stuart Weller, of the University of Chicago, and Dr. J. M. Wetter, of the Illinois State Geological Survey, checked the identifications of Penn- sylvanian invertebrate fossils. Mr. F. C. Baker, Curator of the Natural History Museum, University of Illinois, identified the Pleistocene fossils. Mr. J. H. Markley, Jr., assisted by Mr. A. Prucha, ran precise levels on about 130 stations, which data were used in the) preparation of the structure maps of the area. (Figs. 38, 39, 40, 41.) Members of the Department of Geology of the University of Illinois offered many helpful suggestions. The cordial cooperation and hospitality of the residents of the region, especially those engaged in well drilling, in coal mining, and in the shale industries, is gratefully acknowledged. Fundamental Geologic Processes 1 introductory statement A mere description of the rocks of a region and a discussion of their economic uses does not constitute a geological report. Geology, in a broad sense, is the history of the earth — the record and the interpretation of the changes it has incurred. The earth is not a finished product; under our observation agencies are everywhere changing its surface at the present time, though the rate of such changes is very slow compared with the rate of progress of human events. These agencies have been operative throughout the past, and some of their results have been nothing short of revolutionary. Once or repeatedly areas now land were below the sea for long ages ; re- gions now of gentle relief were the sites of lofty mountains ; some districts where now there is fertile farming land were the scenes of volcanic eruptions, and others were buried beneath thousands of feet of glacial ice; areas now frigid supported palms, fig trees, magnolias, and other subtropical plants. Many of the events of earth history are recorded in the rocks, that is, the rocks are the products of past conditions. The present environment represents the cumulative result of the past environments. Consequently an appreciation of the geology of any region as it is today involves an adequate comprehension of the geological history of that region. By studying the rock formations and interpreting their features as nearly as possible in ac- cordance with current phenomena, geologists have worked out a considerable portion of the past history of the earth. They have subdivided geologic time 1 This section has been adapted from the report on the Geology and Mineral Resources of the Kings Quadrangle, by J. H. Bretz, State Geological Survey Bull. 43, pp. 211-217, 1923. GEOLOGIC PROCESSES 17 into significant intervals, each of which is characterized by a suite of condi- tions that is reflected in the rocks that represent the interval. The major subdivisions are eras and periods (Table 1, p. 30). The transition from one to the other of these major subdivisions was marked by some momentous change that had world-wide effects. Some but not all of these great changes are recorded within the area of the Alexis quadrangle. Running water, ground-water, wind, and man constitute the agencies that are now actively engaged in creating geological changes in the Alexis quadrangle. Their results are gradational and tend to bring the surface of the whole area and adjacent areas to an accordant level. Degradation, or wearing away, is everywhere occurring on the slopes and uplands, and aggra- dation, or building up, is in progress to some extent on the lower tracts. WORK OF RUNNING WATER The average annual rainfall in this region is 34 inches, of which more than a third, perhaps a half, flows down the slopes and converges in the definite water courses. Most of the smaller streams are intermittent and exist only during and immediately after rains and the melting of snow. Others are permanent and persist with a greater or lesser flow throughout the year. These streams, whether intermittent or permanent, are generally more or less muddy, and when in flood they carry sand in suspension and roll pebbles along their bottoms. Such action, continued through centuries, inevitably lowers the surface of the region by removing loose material and abrading more substantial deposits. Measurements of the rate of flow of many Illinois rivers indicate that the run-off per square mile of their drainage basins averages nearly 700,000 tons of water per year. If in its course to the permanent streams this run- off descended a slope averaging 50 feet to the mile, it would produce an average of nearly four and one-half horsepower operating on every square mile of surface. After the water is concentrated in streams, its work is even more pronounced and conspicuous. The adequacy of running water to wear down the land through long intervals of time is thus apparent. WORK OF GROUND-WATER The portion of the precipitation that sinks into the ground constitutes ground-water. All but the uppermost portion of soils and porous rocks is continually saturated. The upper limit of the saturated rock and soil is called the water-table. In general it is nearer the surface in valleys than on hills. The bottoms of many valleys are below the water-table, in which instances springs and seeps may issue at or below the water-table along the lower parts of the valley-slopes and the streams that occupy the valleys will be permanent. 18 ALEXIS QUADRANGLE Depressions whose bottoms are below the water-table will be occupied by lakes or swamps. Wells must be dug or drilled below the water-table in order to assure a permanent source of water. Most quarries, mines, and other excavations that extend below the water-table till with water unless pumps are constantly operated to remove it. Ground-water rarely produces mechanical effects like those which result from surlicial run-off, because generally it only seeps slowly through pores and cracks in the rocks. But it effects other changes by other means, chief of which is solution. The ground-water which issues as springs or seeps or is obtained from wells frequently carries in solution great quantities of mineral matter which it has obtained from the rocks through which it has passed. It is this dissolved material which makes water "hard". When precipitated it constitutes the mineral deposits around springs and forms the scale in teakettles, steam-boilers, and water-pipes. Calcium carbonate, the dominant constituent of limestone, is the chief substance dissolved by the ground-water. Ground-water also reacts on the rocks by means of three chemical pro- cesses — hydration, oxidation, and carbonation — all of which tend to disin- tegrate the solid rocks and reduce them to soil. The three processes are chemical combinations of water, oxygen, and carbon dioxide, respectively, with some minerals or their constituent elements. The oxygen and carbon dioxide are absorbed from the air by the falling rain. Oxidation is best re- vealed by the rusting of iron-bearing minerals in rocks and their eventual development as reddish-stained soils. Carbonation first produces calcium carbonate, which is dissolved by the ground-water. WORK OF STAGNANT WATER Plant debris may be preserved from decay only when it accumulates in expanses of standing water, such as lakes and marshes, where the material gradually becomes peat or muck. Such deposits are now being formed in undrained depressions in the recently glaciated areas of northeastern Illinois, northern Michigan, Wisconsin, Minnesota, and southern Canada. Swamp deposits of peat and muck that were developed in ancient geologic epochs were buried beneath other sediments, and subsequent compression has changed them into beds of coal, such as those which form the principal source of mineral wealth of the Alexis area. The organic acids that result from the decay of plant material leach and deoxidize the underlying soil of its more soluble and more highly oxidized minerals, so that a white or light gray clay is formed. Such clays are found underlying most coal beds. They are called fire-clays, because most of them, when burned, form brick which is especially resistant to high temperatures (fire-brick). GEOLOGIC PROCESSES 19 WORK OF WIND Wind, which is simply air in motion, produces only mechanical changes. When it is bearing loose material it acts like a sand-blast and wears away exposed surfaces of indurated rock. It removes loose material from one place (erosion or degradation) and deposits it in another (aggradation). The ma- terial borne by the wind under ordinary conditions must of necessity be composed of small particles — dust and sand — but under unusual conditions fine gravel and even larger fragments may be moved. Soil may be blown away from areas in which the moisture or vegetation is insufficient to hold it. Sand will accumulate in the lee of any obstacles and there form sand " :.«P? %- , '*'*j , • '. f ' ■:,.._ '■ S .. til % -" /' ,, ^t^m ■^Vifci!^-!' :'>.:,/■ ,| s mUm %l ^ : 4;.: *"*"J EP ; " :■.;¥■;«>''' *•> '■■■Z^-^l*.:.. mmm.m ^WB IWP^ Kmum^:::: ~ ■**»■■• ■■■>.■ . h&- L- .. ' a-« ;^:^-4ffe !: -"--.- 1 Fig. 2. An eight-foot boulder of pink granite from the Kansan glacial drift, in the bed of a creek in sec. 18, T. 12 N., R. 2 W. (Spring Grove Twp.). dunes. The finer constituents may be carried as suspended dust for miles and may be deposited as a widespread mantle of loess. The geological changes above outlined are known to have occurred in this region intermittently in the past, as well as in the present. Other grada- tional changes, of which three will be outlined in the following topics, alter- nated with them. GLACIATION In the Alexis quadrangle most of the non-indurated rock, commonly called the subsoil, is non-stratified stony clay. It contains boulders and pebbles of rocks utterly unlike the subjacent bedrock. Granites (fig. 2) and 20 ALEXIS QUADRANGLE fine-grained lavas which have solidified from a former molten state; gneisses whose twisted and gnarled structures tell of tremendous pressures and move- ments in the throes of mountain-making; red quartz porphyry (an igneous rock consisting of a red, microcrystalline ground-mass in which are set crystals of glassy quartz and pink-to-red feldspar) whose parent ledges are probably north of lakes Superior and Huron; an immense amount of lime- stone; and a great variety of other types of rock foreign to the region are represented in the surficial gravel of road cuts and stream beds. These rocks have been introduced by an agency which carried and de- posited particles of all sizes, from huge boulders to the finest clay, in intimate association. Further, it has dragged them under great pressure, because they are beveled, planed, polished, and scratched and the surface of the bedrock has been smoothed, grooved, and marred with long, parallel scratches that show the direction in which the debris was moved. Neither wind or water can do this. There is but one gradational agent which does these things, and that is glacial ice. The stony clay which it deposits is known as till, or some- times as drift. MARINE SEDIMENTATION The indurated rock, or bedrock, of the region is stratified and consists of sandstones, shales, and limestones. Records of wells and other borings reveal that these rocks extend to a depth of more than 3,000 feet at least. Originally these formations were unconsolidated sands, muds, and calcareous ooze deposited in layers or strata at the bottoms of shallow seas that opened into oceans which then surrounded the continent of North America. When the sands were deposited the shores of the ancient seas were not far inland from this region. The currents created by waves and tides were strong enough to carry the sand grains along the bottom for some distance from the land from which the material was derived. When the calcareous ooze was deposited the shores were perhaps farther inland from this region and the water was probably a little deeper and surely much clearer and less dis- turbed by waves and currents. The ooze consisted largely of the shells and other hard parts of marine animals living in the seas, with which organic debris only mud fine enough to be carried in suspension far from the land was mingled. Subsequent to the deposition of these marine sediments the originally incoherent materials have become indurated, partly by compression but largely by cementation. The cement consists of mineral matter which was intro- duced in solution in ground-water and was precipitated between the grains of the unconsolidated material. The consolidated formations can rarely be traced continuously between two places where they may be exposed. The identification or correlation GEOLOGIC PROCESSES 21 of scattered outcrops must be based on certain features or criteria, which are unique to the formation, and which are widely distributed in it. One reliable criterion for correlation is fossils, which are the impressions or petrifactions of plant or animal organisms that lived in the region while the sediments were being deposited. The existence of fossils has been known for many centuries, but the fact that each of the different formations in one region contains different assemblages of such forms and that any one forma- tion contains the same assemblage wherever it may occur was first recognized in England about 125 years ago. This fact is now established as one of the most important of geological principles. After careful study of the embedded fossil forms, sedimentary formations may be correlated across great gaps, perhaps some hundreds of miles wide, in which no outcrops of these forma- tions occur. DIASTROPHISM The stratified bedrock, with its entombed marine fossils, is undisputable evidence that several times in the past the Alexis quadrangle was inundated by embayments of the oceans. The region now stands several hundred feet above sea-level. These two facts indicate that since the last strata were de- posited the region has been raised, the sea-level has been lowered, or both movements have taken place, to create a differential approaching, if not attain- ing, a thousand feet. Movements in the body of the earth, manifested by warpings of its exterior, explain such changes in altitude. Downwarp of the ocean basins would draw off the waters ; upwarp of the continent, or a part of it, would convert areas covered by shallow water into land. Such movements constitute diastrophism. Should the region as it now exists be again submerged beneath the sea, mud, sand, or calcareous materials would again be deposited, and these would rest on the present irregular surface. The contact between the new deposit and that already deposited would be as irregular as the present topography. (PL II.) Such contacts are termed unconformities. If marine strata occur both above and below an unconformity, the following succession of events is recorded : ( 1 ) the presence of the sea over the region and marine deposi- tion; (2) the withdrawal of the sea and the action of degradational agents; and (3) the return of the sea and the renewal of marine deposition. WEATHERING The sum total of all unobtrusive processes by which solid rock is reduced to an unconsolidated condition is known as weathering. In addition to the processes and agencies already mentioned, the following are worthy of note : ( 1 ) differential expansion and contraction of solid rock from daily changes in temperature; (2) expansional force of the freezing of water in pores 22 ALEXIS QUADRANGLE and crevices; (3) wedge work of plant roots growing in cracks in the rock; and (4) the burrowing of animals. It is obvious that any rock, however firmly indurated, must slowly disintegrate as a result of the attack of these varied agents during the passage of years. Thus a mantle of unconsolidated material — physically and chemically unlike the underlying parent rock — is formed on all outcrops of indurated rock, save those too steep to retain it. This loose material is appropriately termed mantle-rock. Its upper portion, with which is mingled the carbonaceous matter of decayed plant tissues, forms the soil. CHAPTER II Physiography relief and drainage The Alexis quadrangle lies entirety within the Interior Glaciated Plains Province. 1 Topographically the area is a dissected upland plain. The un- dissected remnants which rise gradually from elevations of about 700 feet in the southwest portion to about 800 feet in the northeast portion show that the original surface of the plain was gently rolling. The total relief in the quadrangle is approximately 220 feet, measured between the lowest points of the main streams where they leave the west side of the quadrangle and the highest points on the uplands in the northeast part of the quadrangle. Fig. 3. Pope Creek in sec. 3, T. 13 N., R. 3 W. (Ohio Grove Twp.), show- ing the steep, wooded south slope and the gentle, more open north slope. The present relief is a distinct but considerably modified reflection of the bedrock surface, despite a mantle of glacial drift. In the southern portion of the quadrangle, where the uplands are lower, the drift overlies shale (Kinderhook) ; in the northern portion, where the uplands are higher, it overlies more resistant strata (Pennsylvanian). Most of the principal valleys follow pre-glacial valleys. 1 Fenneman, N. M.. Physiographic division^ of the United States: Annals of the Association of American Geographers, vol. 6, pp. 19-98, 1916. 23 24 ALEXIS QUADRANGLE The quadrangle is drained by five main streams which have rudely parallel courses and flow westward toward Mississippi River. (See PI. I.) Fig. 4. Early stage in the development of gullies on deforested slopes in glacial drift. This condition is typical of small ravines in the area Fig. 5. "Bad-land" topography developed in Pennsylvanian shale on the north slopes, of a large creek valley in sec. 7, T. 14 N., R. 2 W. (Greene Twp.). GEOGRAPHY 25 Their principal tributaries have similar westward courses, and many of them turn almost at right-angles to join the main streams. Numerous smaller tributaries flow north or south into the larger west-flowing streams. There is a marked dominance of tributaries on the north side of all valleys, with regard both to number and development. The slopes of the larger valleys are sufficiently gentle that many of them may be cultivated, and even in some of the longer tributary ravines the slopes are gentle enough to permit cultivation. Most of the valleys have an asymmetric cross-section, with the south wall usually steeper (fig. 3). ■■' Fig. 6. A terrace remnant of a former alluvial plain in a tributary valley. The small creek in the forground has entrenched itself in the former valley-flat since de- forestation along the headwaters. Sec. 5, T. 13 N., R. 1 W. (North Henderson Twp.). The north slopes of most of the valleys have less vegetation than the south slopes and consequently are more affected by recent gullying. The steeper slopes are generally forested or grassed and are thereby protected from gullying. Locally, however, "bad-land" topography has developed in glacial drift (fig. 4) and Pennsylvanian shale (fig. 5). The valleys of the main streams vary from an eighth of a mile to nearly a mile in width. Most of the valleys have a reasonably consistent width across the quadrangle, but the valleys of North Henderson and Pope creeks 26 ALEXIS QUADRANGLE are greatly constricted in the central part of the quadrangle, where their steep walls consist of bedrock beneath a thin veneer of glacial drift. Small valley-flats, composed of alluvial sand and silt, extend far up toward the headwaters of even the smaller tributaries. Terrace remnants of v«alley-flats at higher levels occur in many of the tributary valleys (fig. 6). The valley-flats are subject to flood during periods of heavy rainfall. Following a series of exceptionally heavy rains in August. 1924. the water of Edwards River stood seven feet above a road on the valley-flat in sec. 35, T. 15 X., R. 2 W. (Preemption Twp.). Rains in early June. 1926, transformed parts of the valley-flats of Henderson. Middle Henderson, Pope, and other creeks into great lake-like stretches of nearly stagnant water which existed for nearly a week, seriously damaging crops and making many roads impassable. Geography distribution of population About half of the estimated population of the Alexis quadrangle resides in the rural districts, and consequently urban settlements are few and scat- tered. Aledo, the county seat of Mercer County, is the largest town in the quadrangle and has a population of 2200. Alexis, with a population of 800, is second in size. Other villages, in order of size, are Viola. Little York. Shale City, Burgess, and Gilchrist. The rural population is well distributed and averages four or five families per square mile. The topographic map shows 939 rural houses. The population consists largely of native born Americans. INDUSTRIES Agriculture constitutes the most important industry in the quadrangle, which lies within the corn belt. Corn, with the associated rotational crops of oats, clover, and timothy hay. is grown on the uplands, along gentle slopes, and in the valley-flats. (Fig. 7.) The steeper slopes are occupied by wood- lots or pasture. Hog and cattle raising are concomitant industries of com- mercial importance. At present coal is mined in a number of non-shipping mines which supply part of the coal used locally in both towns and rural districts. Former mining operations on a commercial scale account for the development of the villages of Wanlock. Gilchrist, and Old Gilchrist. Another mineral industry of commercial importance is the manufacture of sewer pipes, drain tiles, wall coping, and flue linings. A large brick plant, operated by the Hydraulic Press Brick Company, is located at Shale City, and another large plant operated by the Northwestern Clay Manufacturing Company, is located at Griffin in sec. 4, T. 14 N.. R. 1 W. (Rivoli Twp.) about a quarter of a mile east of the quadrangle boundary. The larger towns of the area have no manufacturing industries. GEOGRAPHY 27 TRANSPORTATION Railroad transportation in the quadrangle is furnished chiefly by branch lines of Chicago, Burlington and Ouincy Railroad. (PL I.) One branch of this system serves Viola, Gilchrist, and Aledo; another passes through Alexis. Rock Island Southern Railway crosses the quadrangle from north to south and has a branch line from Gilchrist to Aledo, but in 1926 it operated only for freight service. The Minneapolis and St. Louis Railroad crosses the southwestern corner of the quadrangle and passes through Little York. A concrete road (State Highway No. 3) follows the western margin of the quadrangle. Most of the country roads are graded and are frequently dragged ; some of the earth roads which are traveled most frequently are oiled. The hilly sections of the quadrangle have poorer roads, but all are passable except during rainy seasons. ^^^HB 0- - :,";•■ 'ig. 7. A field of corn growing in the . alluvial plain along Pope Creek in sec. 32, T. 14 N., R. 1 W. (Rivoli Twp.). Note the gentle valley-wall in the distance and the steeper wall in the right foreground. CHAPTER III— DESCRIPTIVE GEOLOGY Introduction Strata representing all but the Permian system of the Paleozoic group and deposits representing the Pleistocene and Recent systems of the Cenozoic group (Table 1) are penetrated by deep wells, shallow wells, and other bor- ings (Appendix C, and Pis. V and VI) or are exposed at the surface. The oldest rocks known in the quadrangle belong to the Mt. Simon formation of the Cambrian system and are penetrated only by the Aledo city well. The character of rocks below that horizon can be only surmised. Wherever they are exposed, pre-Cambrian sedimentary rocks are intensely metamorphosed, sharply folded, and intruded by igneous rocks, and presumably they have the same character in Illinois. The oldest rocks exposed at the surface belong to the Kinderhook series of the Mississippian system. Cambrian System introduction The name Cambrian is derived from Cambria, the Roman name for northern Wales, where typical exposures of rocks of this system were first studied. 1 Rocks of the Cambrian system outcrop at only one place in Illinois, 2 but they are penetrated by many deep wells, especially in the northern part of the State. The Aledo well in this quadrangle penetrates 1439 feet of the Cambrian system. All of the Cambrian rocks that are known to occur in Illinois belong to the Croixan (Upper Cambrian) series. CROIXAN SERIES The name Croixan is derived from St. Croix, the name of a river that forms part of the boundary between the states of Minnesota and Wisconsin. In 1874 N. H. Winchell 3 proposed the name St. Croix because the series was best exposed along- that river, but subsequently the name has been simplified. 1 Sedgwick, Rev. A., Edinburgh New Philos. Jour., -vol. 19, p. 390, August 14, 1S35 (abstract). Sedgwick, Rev. A., and Murchison, R. L, On the Silurian and Cambrian systems, exhibiting the order in which the older sedimentary strata succeed each other in England and Wales: Notices and abstracts of Communication, pp. 59-61, appendix to British Assoc. Adv. Sci. Rept. 5th meeting, 1836 (Read August, 1835). 2 Bevan, A. C, Fault block of Cambrian strata in northern Illinois: Abstract, Bull. Geol. Soc. America, vol. 40, No. 1, p. 88, 1929. 3 Winchell, N. H., Sketch of the geology of Minnesota: Geol. and Nat. Hist. Survey of Minnesota, First Annual Rept. for 1872, p. 70, 1873. 29 30 ALEXIS QUADRANGLE The Croixan series consists of sandstones, shales, and dolomites, any of which may possess some of the others' characteristics, and all of which may be glauconitic. It is divided into several formations, namely, in ascending succession, Mt. Simon, Eau Claire, Dresbach, Franconia, Mazomanie, Trem- pealeau, Jordan, Mendota, and Madison. The name Mt. Simon was first applied to the basal sandstone of the Croixan series in 1914. 4 The formation is essentially a fine-grained sand- stone tinted red or brown. The Aledo well ends after penetrating 657 feet of the formation, which is believed to be not far from the total thickness. The name Eau Claire, which is the name of a town in Wisconsin near which the formation is well exposed, was first used also in 1914. 5 The formation is principally shale with some beds of sandstone, limestone, and dolomite. It is only 142 feet thick in the Aledo well, but at Moline, Rock Island County, it is 250 feet thick. Dresbach is the name of a town in Winona County, Minnesota, near which the formation was quarried. 6 The formation is a brownish-gray, yellow, or white, slightly dolomitic sandstone, of which 150 feet was penetrated in the Aledo well. Franconia is also the name of a town in Minnesota, in the vicinity of which the formation was first distinguished. 7 The name Mazomanie was introduced 8 to designate a formation in eastern Wisconsin but in western Illinois it is not distinguishable from the Franconia formation. The Mazomanie-Franconia formation consists principally of dolomitic. sandy shale and pink, fine-grained, dolomitic sandstone with a minor amount of sandy dolomite. Glauconite is generally abundant in most of the formation and gives a strong greenish cast to the rocks. The Aledo well penetrates 215 feet of this formation. The name Trempealeau is derived from Trempealeau Bluff, along Mississippi River. 9 The Trempealeau forma- tion consists of a thick dolomite member (St. Lawrence) and thinner shale and sandstone members (Lodi, Norwalk, et cetera). The Aledo well pene- trates 195 feet assigned to the formation ; at Moline and Monmouth, re- spectively, the formation is 285 and 260 feet thick. Jordan is the name of the town in Minnesota, near which exposures of the formation were early recognized. 10 It is a light gray sandstone with dolomitic cement. Its thick- ness varies from 10 to 121 feet in the region of the Alexis quadrangle ; 90 feet of the formation was penetrated in the Aledo well. The Mendota and Madi- son formations, for which the names were respectively derived from a lake 4 Walcott, C. D., Cambrian geologv and paleontology: Smithsonian Misc. Coll., vol. 57, p. 354, 1914. 5 Idem. 6 Winchell, N. H., Geologv of Minnesota: Geol. and Nat. Hist. Survey of Minnesota, Final Rept., vol. 2, preface, p. 22, 1888. 7 Berkey, C. P., Geology of the St. Croix Dalles: Am. Geol.. vol. 20, p. 373, 1S97. 8 Ulrich, E. O.. Major causes of land and sea oscillations: Wash. Acad. Sci. Jour., vol. 10, pp. 74-76, 1920; Ann. Rept. Smiths. Inst., pp. 333-335, 1922. Ulrich, E. O.. Notes on new names in table formations and on physical evidence of breaks between Paleozoic systems in Wisconsin: Wis. Acad. Sci. Trans., vol. 21, pp. 72-90. 1924. 10 Winchell, N. H.. Geology of the Minnesota Valley: Geol. and Nat. Hist. Survey of Minnesota, Second Ann. Rept. for the year 1873, p. 149, 1874. Group System 39 Sub-syst< Recent >» a S 2 o £ ^ rt *§ Pleistocene o N 3 3 a™ o V U *PIiocene fMiocene fOligocene ^ in *Eocene *Cretaceous Mesozoic fComanchean j-t _:_ • • • ... ! , 1 ( 1 • < t 1 1 ( ' c I I A 7 ' I ORDOVICIAN SYSTEM 31 near the city and the city of Madison, Wisconsin, are not found in the region of the Alexis quadrangle. The Croixan series presumably overlies pre-Cambrian rocks (granite or metamorphosed sedimentary rocks) on a peneplain surface that slopes southward as revealed by surface exposures and by well records in central and southern Wisconsin. An unconformity intervenes, as the Lower and Middle Cambrian series are missing. Another unconformity intervenes be- tween the top of the Croixan series and the overlying strata, as the upper two formations of the Croixan series are missing. The Cambrian rocks of the upper Mississippi Valley were formerly grouped as the ''Potsdam" formation and correlated with the Upper Cambrian rocks of Potsdam, New York. When the Mississippi valley rocks were found not to be identical with those of New York, the name "St. Croix" was sub- stituted. The succession of Cambrian formations in Illinois, known only in deep wells, is correlated as far as possible with the Cambrian formations which outcrop in Wisconsin and Minnesota. 11 Ordovician System introduction The name Ordovician refers to the Ordovices, an ancient tribe of people who, at the time of the Roman Empire, lived in Wales where the rocks of the system are typically exposed. 12 The Ordovician rocks of northern Illinois and adjacent states are divided into three subsystems : Lower Ordovician, which is represented by the Prairie du Chien series ; Middle Ordovician, represented by the Mohawkian series, which contains the St. Peter, Glenwood, Platteville, Decorah, and Galena formations ; and Upper Ordovician, which is represented by the Maquoketa formation. The Ordovician system is represented in the Alexis quadrangle by sedimentary rocks totaling nearly 1000 feet in thickness and interrupted by three erosional unconformities. PRAIRIE DU CHIEN SERIES The name Prairie du Chien was introduced 13 to replace the old name "Lower Magnesian" that had been originally used to designate the strata that lie between the Croixan series and the St. Peter sandstone. The name 11 Thwaites, F. T., The Paleozoic rocks found in deep wells in Wisconsin and Northern Illinois: Jour. Geol. vol. 31, pp. 529-555, 1923. Thwaites, F. T., Stratigraphy and structural geology of northern Illinois, with special reference to underground water supplies: Illinois State Geol. Survey Rept. Inv. No. 13, pp. 24-36, 1927. 12 Lapworth, C, On the tripartite classification of the lower Paleozoic iocks: Geol. Mag., London, new ser. vol., 6, pp. 12-14. 1879. 13 Bain, H. F., Zinc and lead deposits of the upper Mississippi Valley: U. S. Geol. Survey Bull. 294, p. 18, 1906 (cites Lancaster-Mineral Point folio). Grant, U. S., and Burchard, E. F., U. S. Geol. Survey Geol. Atlas Lancaster-Mineral Point folio (No. 145), page 3, 1907. 32 ALEXIS QUADRANGLE is derived from the town of Prairie du Chien, Wisconsin, because near that town typical exposures of the series occur along the bluffs of the Mississippi River valley. The series presumably underlies all of Illinois, as many deep wells encounter it, but it crops out only along Illinois River east of La Salle and in a few other northern Illinois localities. In the Alexis quadrangle, it is penetrated only by the Aledo well. The Prairie du Chien series is 435 feet thick at Aledo, but in the vicinity of Rock Island to the north, it is recorded as varying from 229 to 425 feet thick, and at Monmouth, south of Alexis, it is 525 feet thick. The Prairie du Chien series is usually subdivided into three formations — Oneota, New Richmond, and Shakopee. 14 The Oneota formation consists of gray or buff sandy dolomite and is 205 feet thick at Aledo. The name is derived from a river (now called Upper Iowa), in Iowa along whose valley the formation is well developed. 15 The New Richmond formation consists of white or reddish dolomitic sandstone and is 105 feet thick at Aledo. The name is derived from a town in Wisconsin in the vicinity of which the forma- tion is typically developed. 16 The Shakopee formation is also a gray or buff dolomite with some sand and considerable shale. The name is derived from the town of Shakopee, in Scott County, Minnesota, where it was quarried for lime. 17 The Aledo well penetrates 125 feet of the formation, but the thickness varies greatly, and at some localities in Illinois and adjacent states the formation is entirely missing. The relation between the Prairie du Chien series and the underlying Croixan series can not be determined in the Alexis quadrangle, as the succes- sion is shown in only one drill record, but the fact that the Mendota and Madison formations of the Croixan series are missing indicates that the two series are separated by an erosional unconformity. An erosional uncon- formity also probably separates the Prairie du Chien series from the over- lying St. Peter sandstone, as such a relationship is exposed at some localities in Illinois 18 and at many places in Wisconsin 19 and is supported by the corre- lation of records of numerous wells in both states. This unconformity rep- resents an erosional interval during which relief of several hundred feet was 14 Bain, H. F., Zinc and lead deposits of northwestern Illinois: U. S. Geol. Survey Bull. 246. p. 18, 1905. 13 McGee, W. J., Pleistocene history of northeastern Iowa: U. S. Geol. Survey Eleventh Ann. Rept., pt. 1, p. 333, 1891. 16 Wooster, L. C, Geology of the lower St. Croix district: Geology of Wisconsin, vol. 4, p. 106, 1882. "Winchell, N. H., Geol. and Nat. Hist. Survej- of Minnesota Second Ann. Rept. for 1873, p. 138, 1874. 18 Knappen, R. S., Geology and mineral resources of the Dixon quadrangle: Illinois State Geol. Survey Bull. 49, p. 47, 1926. Cady, G. H., Geology and mineral resources of the Hennepin and LaSalle quad- rangles: Illinois State Geol. Survey Bull. 37, p. 36. 1919. Sauer, C. O., Geography of the Upper Illinois valley and history of development: Illinois State Geol. Survey Bull. 27, pp. 38-39, 1916. 19 Thwaites, P. T., Stratigraphy and geologic structure of northern Illinois with special reference to underground water supplies: Illinois State Geol. Survey Rept. Inv. No. 13, p. 22, 1927. ORDOVICIAN SYSTEM 33 locally developed, 20 and at some places the Prairie du Chien series was com- pletely removed. 21 The Prairie du Chien series is usually correlated with the Beekmantown (Lower Ordovician) of New York. It can not be stated definitely that the sandstone formation designated as New Richmond at Aledo is the true equivalent of the New Richmond formation at the type locality, as lenticular sandstones have been found at various horizons in the series. MOHAWKIAN SERIES ST. PETER FORMATION The St. Peter formation was originally named by D. D. Owen 22 because he saw good exposures of it along St. Peters (now Minnesota) River, near St. Paul, Minnesota. It has been penetrated by many deep wells in Illinois and probably underlies all of the State, but it crops out in limited areas only. 23 Typical exposures occur along Illinois River between La Salle and Ottawa and along Rock River in Lee and Ogle counties in the vicinity of Dixon and Oregon. It underlies all of the Alexis quadrangle, and it has been penetrated in several wells in and near the quadrangle. The typical St. Peter sandstone in this area is commonly light gray and less commonly pink or yellow in color, medium- to fine-grained, and more or less dolomitic. It is composed of well-rounded grains, almost all of which are quartz, whose surfaces are frosted and pitted (fig. 8). Many of the grains have been enlarged by secondary growth or accretion of silica de- posited from ground-water. The sandstone is slightly cemented with mag- nesium carbonate and is highly porous. Greenish shale or red marl occurs in the basal part of the formation at many places, and sandy dolomite occurs in the formation at some localities. The total thickness of the formation in and near the Alexis quadrangle ranges from 40 to 290 feet. The St. Peter sandstone rests unconf ormably on the underlying Shakopee dolomite. Most of the fragments that comprise the conglomerate that occurs in the basal St. Peter beds at some localities consist of residual chert derived by weathering and erosion of the Shakopee formation. The sandstone is correlated with the St. Peter formation in Minnesota chiefly because they have the same stratigraphic position, but they are iden- tical with respect to their lithologic characteristics, the slight cementation, and the secondary enlargment of the quartz grains. 20 Fisher, D. J., Geology and mineral resources of the Joliet quadrangle: Illinois State Geol. Survey Bull. 51, p. 20 and PL III, 1925. 21 Thwaites, F. T., op. cit., p. 23. 22 Owen, D. D., Preliminary report of the Geological Survey of Wisconsin and Iowa: U. S. Gen. Land. Office Rept. 1847 (U. S. 30th Cong. 1st Sess. S. Ex. Doc. 2) pp. 160-173, 1847. 23 Lamar, J. E., Geology and economic resources of the St. Peter sandstone of Illinois: Illinois State Geol. Survey Bull. 53, pp. 14-18, PL I, 1928. 34 ALEXIS QUADRANGLE On the basis of its fossil content the St. Peter sandstone of Minnesota is correlated with the upper Chazy ( Ordovician ) series which is exposed at Chazy, near Lake Champlain, New York. Fig. 8. Photomicrograph of St. Peter sand. The grains marked A and B show respectively a pitted grain and a grain which fitted into a pit. Magnified about 20 diameters. (Photograph by courtesy of U. S. Silica Company.) GLENWOOD FORMATION This' formation was recognized as a more or less distinct lithologic unit in northwestern Illinois, Wisconsin, Iowa, and Minnesota for some time before the name Glenwood was applied to it because it is typically exposed in Glenwood Township, Winneshiek County, Iowa. 24 In its type locality the formation is a shale 15 feet thick, of which the lower 8-10 feet are sandy. Elsewhere the formation consists of sandstone, limestone, dolomite, and shale, in almost every conceivable mixture and alter- nation. 25 The sandstone in the formation differs from the St. Peter sand- pp. 24 Calvin. Samuel, Geology of Winneshiek County: Iowa Geol. Survey, vol. 16, 60-61 and 74-75, 1906. 25 Norton, W. H., et al, Underground water resources of Iowa: Iowa Geol. Survey, vol. 21, pp. 29 et seq., 1912. Bevan, A. C, The Glenwood beds as a horizon marker at the base of the Platteville formation: Illinois State Geol. Survey Rept. Inv. No. 9, 1926. Athy, L. F., Geologv and mineral resources of the Herscher quadrangle: Illinois State Geol. Survey Bull. 55, p. 25, 1928. ORDOVICIAN SYSTEM 35 stone in that it consists mainly of fine, angular grains among which are scattered large rounded grains (fig. 9). A greenish color is typical of the Glenwood beds. The thickness of the formation also varies greatly, ranging from 10 to 60 feet where it is present at all. In well No. 6 (Appendix C), 141 feet is assigned to this formation, but this thickness may include part of the St. Peter formation. The precise limits of this formation can not be satisfactorily differen- tiated in the records of all wells, because its dolomitic and calcareous phases closely resemble the overlying typical Platteville formation and its sandy phases equally closely resemble the underlying St. Peter formation. A minor erosional unconformity occurs between the Glenwood and St. Peter forma- ,» Fig. 9. Photomicrograph of Glenwood sandstone (magnified about 16 diameters). tions at some localities, 26 but in most places the Glenwood beds appear as transitional beds between the St. Peter and Platteville formations. Owing to its arenaceous content, the formation has been allied with the St. Peter formation by some geologists, 27 but most geologists 28 prefer to 26 Bevan, A. C, op. cit., pp. 11-12. 27 Calvin, Samuel, op. cit. 28 Be van, A. C, op. cit. Bain, H. P., Zinc and lead deposits of northwestern Illinois: U. S. Geol. Survey- Bull. 246, p. 19, 1905. Grant, U. S., and Burchard, E. F., U. S. Geol. Survey Geol. Atlas, Lancaster-Mineral Point folio (No. 145), p. 4, 1907. Thwaites, P. T., The Paleozoic rocks found in deep wells in Wisconsin and northern Illinois: Jour. Geol., vol. 35, p. 540, 1923. , Stratigraphy and geologic structure of northern Illinois, with special reference to underground water supplies: Illinois State Geol Survey Rept In v. No. 13, p. 17, 1927. 36 ALEXIS QUADRANGLE classify it as basal Platteville. The slight unconformity between the Glen- wood and St. Peter formations, the variable transition between the Glenwood and Platteville formations, and the occurrence of Platteville fossils in the Glenwood shale 29 support this view. The formation has been further con- sidered 30 to be the equivalent of the Joachim formation of Missouri and southern Illinois. PLATTEVILLE FORMATION The name Platteville was adopted for this formation because its full thickness is typically exposed along Little Platte River west of Platteville, Wisconsin. 31 At the time that the name Platteville was adopted, the forma- tion included both a basal sandy shale member and an upper green shale member that were later respectively designated as the Glenwood and the Decorah formations. Consequently the name Platteville was restricted to apply only to a series of thin beds of brownish-gray dolomitic limestone com- monly separated by thin shale partings. The formation occurs over all of northern Illinois and adjacent parts of Iowa, Wisconsin, and Minnesota. In most places it is 90-100 feet thick but in some localities it becomes as much as 125 feet thick and in others it is only 50 feet thick. A thin shale member noted 50-60 feet above the base of the formation in the Aledo and Monmouth wells may be the Decorah shale, in which case the Platteville formation is limited to that thickness ; or it may be only a shale horizon within the formation. The Platteville formation is not sharply differentiated from either the underlying Glenwood formation or the overlying Decorah formation. It has been correlated with the Upper Stones River series in Tennessee and the Chazy-Lowville series in New York. Formerly it was correlated with the Trenton formation in New York, but later it was discovered that the Platteville formation was not the exact equivalent of the Trenton horizon. 32 DECORAH FORMATION This formation, like the Glenwood formation, was included in the Platte- ville formation until it was specifically designated by the name Decorah because it is well exposed in and near the city of Decorah, Iowa. 33 The formation persists over all of northern Illinois and in Wisconsin, Iowa, and Minnesota, where it has been regularly recognized as the "Green shale". In its type locality it consists of calcareous shale with limestone bands and is there 25-30 feet thick. Elsewhere it is more shaly or more 29 Sardeson, F. "W., U. S. Geol. Survey Geol. Atlas, Minneapolis-St. Paul folio (No. 201), p. 6, 1916. 30 Knappen, R. S., Geology and mineral resources of the Dixon quadrangle: Illinois State Geol. Survey Bull. 49, p. 53, 1926. 31 Bain, H. F., op. cit., p. 19. 32 Bain, H. F., op. cit., pp. 18-19. 33 Calvin, Samuel, op. cit., pp. 60-61 and 84-85. ORDOVICIAN SYSTEM 37 calcareous, and its thickness varies greatly. In the Alexis quadrangle 5 or 10 feet of shale noted in some well records may mark the Decorah horizon, in which case it is probable that some of the superjacent shaly dolomite is also in the Decorah formation. The Decorah formation is correlated with the Lowell Park limestone in the Dixon, Illinois, area 34 and with the Black River formation in New York. GALENA FORMATION The formation derives its name from the fact that in it is found most of the lead-bearing mineral galena that once made the upper Mississippi valley a mineral district important for its production of lead and zinc. 35 Like the Glenwood, Platteville, and Decorah formations, the Galena formation occurs everywhere in northern Illinois and in adjacent parts of Iowa, Wisconsin, and Minnesota. It is a relatively massive, gray cherty, coarsely crystalline magnesian or dolomitic limestone, which weathers to a yellow color and a sandlike texture. The thicknesses of the Galena formation in three drill records in the Alexis quadrangle are 232, 240, and 253 feet, but if the shale horizon, already discussed, is not the Decorah formation, these thicknesses may be reduced. In other well records in the region, the thickness of rock strata assigned to the Galena formation ranges from 180 to 259 feet. The total thickness of the Galena and Platteville formations combined ranges from 280 to 334 feet. In northern Illinois an erosional unconformity of small relief has been reported at the base of the Galena formation, but the drill records in this quadrangle do not show any evidence of such unconformity. CINCINNATIAN SERIES MAQUOKETA FORMATION The Maquoketa formation is named from exposures along the Little Ma- quoketa River in Iowa. 36 It underlies most of northern Illinois and is re- corded in several drill records in the Alexis quadrangle and adjacent territory. The Maquoketa formation consists of gray or brown calcareous shales interbedded with thin limestones. A limestone or dolomitic limestone from 15 to 30 feet thick persists near the middle of the formation. The beds above this limestone are principally shale, with thin beds of limestone, whereas the beds below it vary from calcareous or dolomitic shale, red, brown, or gray in color, to drab-colored, shaly dolomite. In the Alexis quadrangle and vicinity the Maquoketa formation ranges from 160 to 265 feet in thickness, but in most records the thickness ranges 34 Knappen, R. S., op. cit.. p. 60. 35 Foster, J. W., and Whitney, J. D., Geology of the Lake Superior Land District, Part 2: 32d Cong. spec, sess., S. Ex. Doc. 4, p. 146, 1851. 38 White, C. A., Geology of Iowa, vol. 1, p. 181, 1870. 38 ALEXIS QUADRANGLE from 195 to 215 feet. The formation becomes thinner from north to south across the region. It is believed to rest unconf ormably on the' Galena forma- tion. The Maquoketa formation in the Alexis quadrangle is correlated with the Maquoketa beds of Iowa because they have identical stratigraphic position and lithologic character. The upper part of the Maquoketa formation of Iowa and northwestern Illinois is correlated with the lower Richmond (Fernvale and Waynesville) of Indiana and Ohio on the basis of fossil evidence. 37 Although three zones within the Maquoketa formation can be recognized in the records of wells in the Alexis quadrangle, they are probably not widely distributed through the State. Silurian System introduction The name Silurian, which is applied to a system of rocks that occurs below the "Old Red Sandstone" (Devonian), is derived from Silures, the Roman name for a Celtic tribe who formerly inhabited a region that now includes parts of both England and Wales, where the system is typically exposed. 38 At first the system was divided into the Lower and Upper Silurian subsystems, but the lower division was subsequently recognized as a distinct system and named Ordovician. The Silurian rocks in Illinois are divided into two series, the Alexandrian and the Niagaran, and a third series, the Cayugan, may be represented. Only the Niagaran series is known to occur in the Alexis quadrangle. The Alex- andrian series may also occur but cannot be differentiated in well records. NIAGARAN SERIES The name Niagaran was adopted to< designate this series because Niagara Falls, which is produced by the passage of Niagara River over a precipitous ledge of the limestone rocks of the series, exhibits the greatest natural devel- opment of the series in New York state. 39 Rocks of Niagaran age outcrop extensively in northeastern, northwestern, and southwestern Illinois and in adjacent parts of Wisconsin, Iowa, and Missouri. They underlie most of the State, being absent only where they have been eroded after diastrophic elevation exposed them at the surface. They are present under all of the Alexis quadrangle and surrounding area. 37 Savage, T. E., Richmond. Rocks of Iowa and Illinois: Amer. Jour. Sci., 5th ser., vol. 8, pp. 411-427, 1924. 38 Murchison, R. I., On the Silurian system of rocks: London and Edinburgh Philos. Mag. and Jour. Sci., 3d ser., vol. 7, pp. 46-52, July, 1835. 30 Hall, James, Report of the Survey of the fourth geological district: Natural History of New York, part 4, Geology of New York, vol. 4, p. 80, 1843. DEVONIAN SYSTEM 39 The rocks of this series in the upper Mississippi Valley are assigned to the Lockport subseries and have been subdivided into the Joliet, Waukesha, Racine, and Port Byron formations. 40 But these formations cannot be satisfactorily differentiated in well records, so all the Silurian rocks in the Alexis quadrangle and vicinity are treated as a single combined Niagaran unit. They consist of massive, gray, fine-grained, crystalline dolomite and dolomitic limestone, in which there is more or less chert and some pyrite. According to well records in the Alexis quadrangle, the Niagaran rocks vary in thickness from 125 to 200 feet, but in the vicinity of Rock Island, north of the Alexis quadrangle, they range in thickness from 276 to 375 feet, and at Monmouth, south of the Alexis quadrangle, their thickness is only 40 to 58 feet. It is thus apparent that the Niagaran series in this region thins rapidly from north to south. The Niagaran rocks rest unconformably on the Maquoketa formation, but the relatively uniform thickness of the Maquoketa formation suggests that there are only slight irregularities on its upper surface. They are in turn overlain unconformably by the Devonian system, and the great range in their local thickness represents the relief that exists on the upper surface of the Niagaran series. The Niagaran rocks in this quadrangle are correlated with other Niag- aran rocks of Illinois on the basis of identical stratigraphic position and similar lithologic characteristics. Devonian System INTRODUCTION The name Devonian was proposed for this group of rocks because they are typically exposed in Devonshire, England. 41 The term was substituted for a much older name, "Old Red Sandstone", because rocks other than sandstone were discovered to be its equivalent in many localities. Except in localities where they have been removed by erosion, Devonian rocks are presumed to underlie all of that portion of Illinois that lies south of Green River (Rock Island to La Salle) and southwest of a line drawn southeast from La Salle through Danville. They crop out in limited areas only along the outer border of this region — Hardin County and Alexander, Union, and Jackson counties in southern Illinois; Jersey and Calhoun coun- ties in southwestern Illinois ; and Rock Island and Henry counties in north- western Illinois. 40 Savage, T. E., Silurian rocks of Illinois: Bull. Geol. Soc. America, vol. 37, pp. 513-534, 1926. 41 Sedgwick, Rev. A., and Murchison, R. I., Geol. Soc. London Proc, vol. 3, No. 63, pp. 121-123, abstract, 1839. , On the physical structure of Devonshire, and on the subdivisions and geological relations of the older stratified deposits, etc: Geol. Soc. London Trans., 2d ser., vol. 5, pt. 3, pp. 701-702, 1840. (Read April 24, 1839.) 40 ALEXIS QUADRANGLE The Devonian system has been subdivided into Lower, Middle, and Upper Devonian subsystems. The Devonian rocks of northwestern Illinois, which are well exposed along both banks of Mississippi and Rock Rivers in the vicinity of Rock Island, Illinois, belong to the Upper Devonian sub- system 42 and are divided into two formations, the Wapsipinicon and the Cedar Valley. 43 SENECAN SERIES WAPSIPINICON AND CEDAR VALLEY FORMATIONS The Wapsipinicon formation was so named because exposures of the whole formation occur along Wapsipinicon River in Iowa, 44 and the Cedar Valley formation is so designated because it was first studied along Cedar River, also in Iowa. 45 As it is impossible to distinguish these formations in well records, they are described together in this report. Both formations consist principally of massive and thin beds of lime- stone, some of which are shaly and some of which are dolomitic; some of the beds are coarsely crystalline. Thin beds of shale are also* reported, and chert is locally abundant. The combined thickness of the formations ranges from 100 to 200 feet. A horizon of porous limestone 20 to 25 feet thick, reported as a "blue sand" in all wells which have been drilled to it, is the source-bed of water for numerous wells in the quadrangle (Appendix C, wells 32-84). This horizon may be the basal portion of the Devonian strata ; it may be the upper weathered portion of the Niagaran series ; it may be a combination of the two; or it may be only an irregular horizon or a series of porous lenses in both Devonian and Silurian strata, in which case it possesses no stratigraphic import. The marked thinning of the Niagaran series from north to south across the area from Rock Island to Monmouth indicates that an erosional uncon- formity intervenes between the Silurian and Devonian systems. If the porous zone be the base of the Devonian strata, its varied elevations indicate that the unconformity had considerable relief. The Devonian strata in the Alexis quadrangle are correlated with the Devonian strata exposed about 30 miles north of the quadrangle. 46 They are also correlated with the Tully formation of New York, the lowest forma- 42 Savage, T. E., Devonian formations of Illinois: Am. Jour. Sci., 4th ser., vol. 49, pp. 181-182, 1920. 43 Savage, T. E., and Udden, J. A., The geology and mineral resources of the Edging- ton and Milan quadranges: Illinois State Geol. Survey Bull. 38C, pp. 24-28, 1921; Bull. 38, pp. 136-140, 1922. 44 Norton, "W. H., Notes on the lower strata of the Devonian series in Iowa: Iowa Acad. Sci. Proc. 1893, vol. 1. pt. 4, pp. 22-24, 1894. 45 Owen, D. O., Report of a geological survey of Wisconsin, Iowa, and Minnesota and incidentally of a portion of Nebraska Territory, 1852. 46 Savage, T. E., and Udden, J. A., Geology and mineral resources of the Edgington and Milan quadrangles: Illinois State Geol. Survey, Bull. 38C, pp. 24-28, 1921; Bull. 38, pp. 136-141, 1922. MISSISSIPPIAN SYSTEM 41 tion of the Upper Devonian subsystem. 47 The fauna of these limestones indicates that the Devonian seas in this area were connected with the Arctic and Pacific oceans, probably by way of the McKenzie River and the northern Great Plains. Mississippian System introduction The term Mississippian was proposed and is used by most North Amer- ican geologists as a geographical designation for this system of rocks because they are so largely developed in the basin of Mississippi River. 48 The name Carboniferous, which means "coal-bearing", has been long used 49 and is retained as a system term by some American and by European geologists, who refer to rocks equivalent to the Mississippian system as "Lower Car- boniferous". The Mississippian system, like the Devonian system, is distributed over that portion of Illinois that lies south and southwest of a line drawn east from Rock Island to La Salle and thence southeast to Danville. It is divided into two subsystems: the Lower Mississippian, which includes the Kinder- hook, Osage, and Meramec series ; and the Upper Mississippian, which con- sists of the Chester series. The Upper Mississippian subsystem and the Meramec series of the Lower Mississippian subsystem are not represented in the Alexis quadrangle. KINDERHOOK SERIES The name Kinderhook was proposed to include the beds lying between the "Black Slate" and the Burlington limestone 50 because the series as such was first examined at Kinderhook, Illinois. 51 The series underlies all of the Alexis quadrangle except a small area in the west central portion from which it has been removed by erosion. In southwestern Illinois it has been divided into five formations — the Grassy Creek shale, the Saverton shale, the Louisiana limestone, the Hannibal forma- tion, and the Chouteau limestone 52 — but farther north the Louisiana and Chouteau limestones disappear and the Grassy Creek and Saverton shales become a single unit designated the Sweetland Creek shale. 53 The Sweetland Creek and the Hannibal formations only are present in the Alexis quadrangle. 47 Idem. 48 Winchell, A., On the geological age and equivalents of the Marshall group: Ameri- can Philos. Soc. Proc. vol. 11, No. 81, p. 79, 1869; No. 83, pp. 245 and 385, 1870. 49 Conybeare. W. D., and Phillips, W., Outlines of the geology of England and Wales, pp. vii, 278, and 320-364, 1822. 50 Meek, P. B., and Worthen, A. H., Note (p. 288) to "Remarks on the age of the Goniatite limestone at Rockford, Indiana, and its relations to the "Black Slate" of the western states, and to some of the succeeding rocks above the latter" (pp. 167-177): Am. Jour. Sci. and Arts, 2d ser., vol. 12, 1861. 51 Meek, F. B., and Worthen, A. H., Geoh Survey of Illinois, vol. 1, Geology, p. Ill, 1866. 52 Moore, R. C., Early Mississippian formations in Missouri: Missouri Bureau of Geol. and Mines, 2d ser., vol. 21, pp. 33-76, 1928. 53 Idem, p. 36. 42 ALEXIS QUADRANGLE SWEETLAND CREEK FORMATION The Sweetland Creek formation is so named because its relations are best exhibited along Sweetland Creek in Muscatine County, Iowa. 54 It un- derlies all except the southwest part and other local areas of the Alexis quadrangle, from which it has been eroded. The formation constitutes the lower part of a thick shale series that lies between the Devonian limestones and the Burlington (Lower Mississippian) limestone. It is brownish-gray or gray in color, and in many layers the tiny spore-cases of a fern-like plant named Sporangites huronense, occur in great abundance. The precise thickness of the Sweetland Creek formation can not be determined everywhere in the quadrangle, because in well records the forma- tion can not be differentiated from the overlying Hannibal shale and higher Pennsylvanian shales unless samples of cuttings have been preserved and are available for study. Well records (Appendix C) reveal that the forma- tion is absent in the west central part of the quadrangle and that 130 feet of it intervenes between Devonian limestone and Pennsylvanian strata at Aledo. At Monmouth, six miles south of the quadrangle, the lower 190 feet of a 280-foot shale horizon between Devonian and Mississippian limestones is assigned to the Sweetland Creek formation on the basis of a study of samples of well cuttings. If this be assumed the normal full thickness of the forma- tion in the general area, a similar thickness probably occurs at some places in the Alexis quadrangle, as for instance in the SE. corner NE. %. NE. y^ sec. 29, T. 12 N., R. 2 W. (Spring Grove Twp.), where the driller's record of a farm well reveals 210 feet of shale at the same horizon. In this area the Sweetland Creek shale apparently rests conformably on the underlying Cedar Valley limestone but in Iowa an unconformity inter- venes between them, and farther south in Illinois and in Missouri the Sweet- land Creek formation or its equivalent, the Grassy Creek formation, overlaps strata ranging downward from Devonian to Middle Ordovician in age. 55 The change from limestone (Cedar Valley) to shale (Sweetland Creek) in the Alexis area reflects the unconformable relations elsewhere. So far as known, the Sweetland Creek formation conforms with the overlying Hanni- bal formation where both formations occur. This condition exists only in the south part of the Alexis quadrangle; in other parts of the quadrangle and in areas adjacent to such parts the Sweetland Creek formation is overlain unconformably by Pennsylvanian strata or Pleistocene deposits. The varia- tion in thickness of the Sweetland Creek formation and its unconformable relations with Pennsylvanian and Pleistocene formations are consequences of both post-Mississippian, pre- Pennsylvanian and post-Pennsylvanian, pre- Pleistocene erosion. E4 Udden, J. A., Geology of Muscatine County: Iowa Geol. Survey Ann. Rept. 1S98, vol. 9, p. 291, 1899. , The Sweetland Creek beds: Jour. Geol., vol. 7, p. 67, 1899. 55 Moore, R. C, Op. cit., p. 34. MISSISSIPPIAN SYSTEM 43 The Sweetland Creek formation in the Alexis quadrangle is directly correlated with the type Sweetland Creek formation in Iowa, on the basis of identical stratigraphic position and similar lithologic character. It has been also considered the equivalent of the Grassy Creek shale in northeastern Mis- souri ; the Mountain Glen shale in Union County, Illinois ; the Chattanooga shale in Kentucky and Tennessee; and the "Chattanooga" shale in south- western Illinois, southern Missouri, and Arkansas. Formerly all of these local developments of a supposedly equivalent formation were considered to be of Late Devonian age, but more recently many geologists have presented evidence 56 that they are actually Early Mississippian in age. HANNIBAL FORMATION The name Hannibal was applied to this formation because typical out- crops of it occur near Hannibal, Missouri. 57 The formation occurs in prac- tically the same portion of the State in which the Devonian system and Sweetland Creek formation occur. It underlies only the south part of the Alexis quadrangle and outcrops at a few localities in T. 12 N., R. 3 W. (Sumner Twp.), and T. 12 N., R. 2 W. (Spring Grove Twp.). It is the oldest formation exposed in the quadrangle. In its type locality the Hannibal formation consists of sandstone ("Vermicular") and shale, and elsewhere in Iowa, Missouri, and Illinois it includes a magnesian limestone member, 58 but as seen in exposures and in samples of well cuttings and as reported in well records in the Alexis quad- rangle it is a light gray or greenish-gray, soft, non-fossiliferous clay-shale without hard bands. Its color and the absence of Sporangites distinguish it from the underlying Sweetland Creek shale. One of the best exposures of the Hannibal shale in the Alexis quadrangle is in a road-cut on the south side of Henderson Creek, at the SW. corner sec. 2, T. 12 N., R. 3 W. (Sumner Twp,), where about 8 feet of the shale is exposed. The normal full thickness of the Hannibal shale in this region is slightly more than 100 feet, as revealed by well records. At Monmouth, six miles south of the Alexis quadrangle, the upper 90 feet of the 280-foot shale series between Devonian and Burlington (Mississippian) limestones is as- signed to the Hannibal formation, but as a consequence of both post-Missis- 56 Moore, R. C, op. cit., including numerous citations to other authors, Mylius, L. A., Oil and gas development and possibilities in east-central Illinois: Illinois State Geo!. Survey Bull. 54, pp. 53-57, 59-65, 1927. Swartz, Joel H., The age of the Chattanooga shale of Tennessee: Am. Jour. Sci., 5th ser., vol. 7, pp. 24-30, January 1924. , The age of the Big Stone Gap shale of southwestern Virginia: Am. Jour. Sci., 5th ser., vol. 12, pp. 512-531, December 1926. , Chattanooga shale in eastern Tennessee and Virginia (abstract): Bull. Geol. Soc. America, vol. 39, No, 1, p. 201, March 1928. , Devono-Mississippian boundary in Virginia and Tennessee (ab- stract) : Bull. Geol, Soc. America, vol. 40, No. 1, p. *93, 1929. 57 Keyes, C. R., The principal Mississippian section: Bull. Geol. Soc. America, vol. 3, pp. 283-300, 1892, 58 Moore, R. C, op. cit., pp. 20-24, 33, 50-60. 44 ALEXIS QUADRANGLE sippian, pre-Pennsylvanian and post-Pennsylvanian, pre-Pleistocene erosion the formation thins rapidly to the north and has been removed from all but the south part of the Alexis quadrangle. Only the upper 20 feet of a 210- foot shale series between Devonian limestone and Pennsylvanian sandstone, reported in a farm well in the SE. corner NE. y A NE. % sec. 29, T. 12 N., R. 2 W. (Spring Grove Twp.) (Appendix C, well No 26), may be assigned to the Hannibal formation, because : ( 1 ) the normal thickness of the Sweet- land Creek formation is assumed to be approximately 190 feet, as at Mon- mouth; (2) there is in this area no unconformity between the Sweetland Creek and Hannibal formations which would suggest a thinning of the Sweetland Creek formation; and (3) the occurrence of Pennsylvanian sand- stone overlying Hannibal shale is evidence that post-Mississippian, pre- Pennsylvanian erosion removed all of the Mississippian strata younger than the Hannibal formation and doutbless cut partly into the Hannibal shale itself at this locality. The Hannibal formation apparently conforms with the Sweetland Creek formation, but the lighter, greenish-gray color and the absence of Sporangites in the Hannibal shale suffice to distinguish it from the dark colored, Spor- angites-besiring Sweetland Creek shale. A disconformity intervenes between the Hannibal formation and the overlying Burlington limestone, but as a consequence of the post-Mississippian, pre-Pennsylvanian and the post- Pennsylvanian, pre-Pleistocene erosions, the Hannibal formation in most of the area in which it underlies the Alexis quadrangle lies unconformably be- neath Pennsylvanian and Pleistocene strata. The upper limit of the Hannibal formation is exposed in only two places in the Alexis quadrangle: Geologic section 1. — Small gully near middle of north line of sec. 30, T. 12 N., R. 2 W. (Spring Grove Twp.) Mississippian system Thickness Burlington formation Feet 3. Chert, crinoidal 1 2. Limestone, purple or buff 2 Hannibal formation 1. Shale, blue-gray, soft Ay 2 Geologic section 2. — Small gully in the SE. T /\ SE. Y\ sec 22, T. 12 N., R. 2 W . (Spring Grove Twp.) Pennsylvanian system Thickness Pottsville formation Feet 2. Sandstone, coarse-grained and thick bedded, and conglomerate con- taining fragments of Burlington limestone and chert 3 + Mississippian system Hannibal formation 1. Shale, blue-gray, soft 1 + MISSISSIPPIAN SYSTEM 45 The Hannibal shale in the Alexis quadrangle is correlated with the Hannibal formation of western Illinois on the basis of similar lithologic characteristics and similar stratigraphic position. OSAGE SERIES The name Osage was proposed to designate one of three major pale- ontological subdivisions of the Mississippian system, 59 and presumably refers to Osage River in southwestern Missouri, which cuts through the series. 60 The series includes four formations — Fern Glen, Burlington, Keokuk, and Warsaw. Neither the typical Fern Glen formation nor its better-developed limestone equivalent in western Illinois, which has been recently designated the Sedalia formation, 61 have been recognized in the Alexis quadrangle, although the purple color of the limestone member in geologic section No. 1 is characteristic of the Fern Glen formation. The Keokuk and Warsaw forma- tions are absent in the quadrangle. Apparently they were removed by pre- Pennsylvanian erosion. BURLINGTON FORMATION The Burlington formation was so< named because excellent exposures of it occur at Burlington, Iowa. 62 The formation as typically developed under- lies all of western Illinois south of Mercer County. It underlies only a very small area along the south edge of Alexis quadrangle, as it crops out only along the banks and in tributary gullies of a small stream along the north side of the NE. y A sec. 30, T. 12 N., R. 2 W. (Spring Grove Twp.), and is recorded in only a single well which is located nearby in the SE. corner of sec. 19, same township. This occurrence is believed to mark the northern limit of the present distribution of the Burlington formation. The presence of fragments of Burlington limestone and chert in the basal Pennsylvanian conglomerate suggests that the Burlington formation originally extended over all of the quadrangle but was removed by pre-Pennsylvanian erosion. The Burlington formation is a gray, coarsely crystalline, very fossilifer- ous limestone. Fragments of crinoids constitute such a large proportion of the calcareous material composing the limestone that it has been long recog- nized as the "Crinoidar or "Encrinital" limestone. It contains much chert in concretions and discontinuous bands, and most of the Burlington material exposed at the one outcrop in the Alexis quadrangle is chert, in which there are many traces of fossils. The internal casts of shells have been removed by solution, and the surfaces of the resulting hollow external molds are lined with fine crystals of calcite. 59 Williams. H. S., Correlation papers — Devonian and Carboniferous: U. S. Geol. Survey Bull. 80, p. 169, 1891. 60 Keyes, C. R., Geological formations of Iowa: Iowa Geol. Survey, vol. 1, pp. 59-60. 1892. 61 Moore, R. C, op. cit. 62 Hall, Jamesi, Observations upon the Carboniferous limestones of the Mississippi Valley: Am. Jour. Sci., 2d ser., vol. 23, p. 190, 1857. 46 ALEXIS QUADRANGLE The single outcrop of the formation in the quadrangle exposes only 3 feet of limestone and chert, but before it was truncated by pre-Pennsylvanian erosion the formation was probably 150 to 200 feet thick. The Burlington limestone appears to overlie the Hannibal shale con- formably. It is also conformable with the overlying Keokuk formation wherever both formations occur. But in the Monmouth quadrangle to the south the Burlington formation is overlain by Pennsylvanian strata with a marked erosional unconformity between them. The Burlington limestone in the Alexis quadrangle is the basal part of the formation. The formation is correlated with the typical Burlington limestone on the basis of its identical stratigraphic position and lithologic character. It is also doubtless equivalent to a portion of the beds which occur in southern Illinois and adjacent states and which have been designated by various local names but are correlated with the whole Osage series. Pennsylvanian System introduction The term Pennsylvanian was proposed as a synonym for the terms "Upper Carboniferous" and "Coal Measures," 63 because excellent exposures of the coal-bearing rocks were first thoroughly studied in the State of Penn- sylvania. Like the term Mississippian, it has been recognized only as a series term by the United States Geological Survey and it has not been generally adopted in Europe. Rocks of the Pennsylvanian system underlie all except the north part, west border, and south end of Illinois and occupy what is familiarly known as the "Illinois Coal Basin" (fig. 1). They underlie all of the Alexis quad- rangle except T. 12 N., R. 3 W. (Sumner Twp.) and parts of T. 13 N., R. 3 W. (Ohio Grove Twp.), T. 12 N., R. 2 W. (Spring Grove Twp.), and T. 13 N., R. 2 W. (Suez Twp.), where they were removed by preglacial erosion. Basal Pennsylvanian shales cannot be distinguished from the Han- nibal and Sweetland Creek shales in records of borings unless samples of the well cuttings are available for study. Pennsylvanian strata in the Alexis quadrangle rest unconformably on the Burlington limestone, Hannibal shale, Sweetland Creek shale, and perhaps the Cedar Valley limestone (PI. II). The base of the Pennsylvanian is exposed in only one outcrop. (Geologic section 2, p. 44.) Wherever Penn- sylvanian strata occur in the Alexis quadrangle, they are overlain uncon- formably by glacial drift of Pleistocene age. The sub-Pennsylvanian surface in the Alexis quadrangle is markedly irregular. (PI. II.) Some pre-Pennsylvanian river channels approximately 03 Williams, H. S., The geology of Washington County: Arkansas Geol. Survey Ann. Rept. for 1888, vol. 4, p. xiii, 1891. PENNSYLVANIAN SYSTEM 47 100 feet deep are known to exist, and the shale-filled depressions on the Devonian limestone surface (fig. 39) may be also pre-Pennsylvanian channels, although the shale can not be positively identified as Pennsylvanian. A pre-Pennsylvanian highland, reflecting the superior resistance of the Burling- ton limestone, existed just south of the quadrangle and a spur of it projected northward into the southwest portion of the quadrangle. A general lowland excavated in the weaker Sweetland Creek and Hannibal shales occupied most of the quadrangle. When the Pennsylvanian sea transgressed the area, it submerged the channels and lowlands first and covered them for some time before the highlands were submerged. Basal Pennsylvanian sediments at all localities in the quadrangle therefore are necessarily not of the same age. The Pennsylvanian system consists of shales, sandstones, underclays, coals, limestones, and conglomerates, listed in order of abundance. Its maxi- mum known thickness in the Alexis quadrangle is about 250 feet, as deter- mined by borings in sec. 8, T. 14 N., R. 2 W. (Greene Twp.), but its average thickness is much less. SUBDIVISIONS The Pennsylvanian system in Illinois is divided into three formations — Pottsville, Carbondale, and McLeansboro — which, according to paleobotanical evidence, 63a are approximately equivalent respectively to the Pottsville, Alle- gheny, and Conemaugh formations in the Appalachian province. The paleo- botanical data reveal that all Pennsylvanian strata between and including coals No. 2 (Murphysboro) and No. 6 (Herrin) and possibly No. 7 (Dan- ville) in Illinois belong in the Allegheny formation, 63 * but thus far they do not reveal the precise horizons at which the upper and lower boundaries of the formation may be drawn, except that the lower (Pottsville- Allegheny) limit occurs somewhere between the base of the Murphysboro (No. 2) coal and the "fireclay''' series that is commercially exploited at various places in the State. 63b Consequently the local names Carbondale and McLeansboro were adopted in place of Allegheny and Conemaugh, and for convenience the boundaries between the formations were arbitrarily drawn respectively at the base of the underclay beneath the Murphysboro (No. 2) coal at first 630 and later at the base of the coal itself csd and at the top of the Herrin (No. 6) or Danville (No. 7) coal. 63c ' 63d Further paleobotanical, paleontological, 63a White, David, Report of the field work in the coal districts of the State: Illinois State Geol. Survey Bull. No. 4 (Year-Book for 1900), pp. 201-203, 1907. White, David, Report on field work done in 1907: Illinois State Geol. Survey Bull. No. 8 (Year-Book for 1907), pp. 268-272, 1908. White, David, Paleobotanical work in Illinois in 1908: Illinois State Geol. Survey Bull. No 14 (Year-Book for 1908), pp. 293-295, 1910. 63b White, David, Paleobotanical work in Illinois in 1908: Illinois State Geol. Survey Bull. No. 14 (Year-Book for 1908), p. 294. esc Shaw, E. W., and Savage, T. E., U. S. Geol. Survey Geol. Atlas, Murphysboro- Herrin folio (No. 185), p. 6, 1912. Udden, J. A., and Shaw, E. W., U. S. Geol. Survey Geol. Atlas, Belleville-Breese folio (No. 195), p. 4, 1915. Hinds, Henry, U. S. Geol. Survey Geol. Atlas, Colchester-Macomb folio (No. 20S). p. 5, 1919. Shaw, E W.. U. S. Geol. Survey Geol. Atas, New Athens-Okawville folio (No. 213), p. 4, 1921, and Carlyle-Centralia folio (No. 216), p. 4, 1923. 48 ALEXIS QUADRANGLE and stratigraphic investigations now in progress may provide data by which the formation boundaries may be accurately determined. The Pennsylvanian rocks in the Alexis quadrangle belong to the Potts- ville and Carbondale formations and are so designated on the geologic map (PL I). They are separated at the base of a coal bed that is correlated with the Colchester coal in western Illinois, which in turn has been considered to be the equivalent of the Murphysboro (No. 2) coal. During the geological survey of the Alexis quadrangle, a natural group- ing of the Pennsylvanian strata was noted, due to the fact that the same succession of beds is repeated several times, each sequence being demarcated at least locally by unconformities both below and above (PL II). In this report the Pennsylvanian system is discussed in accordance with this group- ing, but the definition of the standard classification is preserved. A succes- sion of sequences in the Peoria quadrangle had been noted earlier 63e and additional investigations carried on by the author and other men over a considerable portion of western Illinois since the Alexis area was studied show not only that the typical sequences occur commonly but also that the various members within the sequences, even very thin ones, are remarkably persistent. The possible importance of repeated sequences in the interpreta- tion of Pennsylvanian stratigraphy is indicated by the fact that they can be recognized' in other states, where it has also been shown that individual mem- bers of such sequences are traceable over wide areas. For instance, in Nebraska and adjacent states about 150 individual strata, some of them only a few inches thick, have been distinguished and recognized as continuous over extensive areas. 63f A similar situation exists in Ohio. 63g The sequences are interpreted as each representing the record of sedimentation within a cycle of time, part of which is occupied by uplift and erosion. 63h In this report the term suite is used to designate each of the natural sequences. Numbers are herein applied to the suites, but after more ex- tended studies have revealed the most typical outcrops of each suite it will probably prove desirable to supplant the numbers with names derived from 63d Shaw, E. W.. and Savage, T. E., U. S. Geol. Survey Geol. Atlas, Springfield- Tallula folio (No. 188), p 3, 1913. Lee, Wallace, U. S. 'Geol. Survey Geol. Atlas. Gillespie-Mt. Olive folio (No. 220), p. 3. 1926. Lines, Edwin F., Stratigraphy of Illinois with reference to Portland-cement material: Chap. IV; Portand- cement resources of Illinois: Illinois Geol. Survey Bull. No 17, pp. 73-74, 1912. All later publications of the Illinois State Geol. Survey. 63e Udden, J. A... Geology and mineral resources of the Peoria quadrangle, Illinois: U. S. Geol. Survey Bull. No 508, pp. 47-50, 1912. 63f Condra, G. E., The stratigraphy of the Pennsylvanian system in Nebraska: Nebraska Geol. Survey, Vol. I, second series, 1927. Condra, G. E., Dunbar, C. O.. and Moore, R C. Persistence of thin beds in the Pennsylvanian of the northern midcontinent region (abstract): Preliminary list of titles and abstracts of papers to be offered at the 42nd annual meeting of the Geol. Soc. America, 1929. 63g Consult various bulletins published recently by the Ohio State Geological Survey. 63h Udden, J. A., Op. cit. Weller, J. Marvin, Cyclical sedimentation of the Pennsylvanian period and its significance: Jour of Geol. vol. 38, No. 2, February-March, 1930. Moore, Raymond C, Sedimentation cycles in the Pennsylvanian of the northern midcontinent region f abstract): Preliminary list of titles and abstracts of papers to be offered at the 42nd annual meeting of the Geol. Soc. America, 1929. PENNSYLVANIAN SYSTEM 49 the localities at which such outcrops occur. Suites II and IV in the following table are typical and comprise, from bottom to top, a sandstone or sandy shale, an underclay, a coal, a black laminated shale, a limestone, and a gray shale. The sandstone, sandy shale, underclay, and coal are believed to have been formed under continental conditions ; the black laminated shale, lime- stone, and gray shale are marine deposits. The author has found that in western Illinois suites II and IV are widespread ; that suites I and III are composite ; and that there are additional suites not represented in the Alexis quadrangle. Therefore the enumeration in this report represents the status of these investigations and the views of the author at the time that the geological survey of the Alexis quadrangle, was completed. Generalised geologic section of Pennsylvanian strata in the Alexis quadrangle Thickness Feet Carbondale formation Suite V. d. Clay or shale 5 c. Coal y 2 b. Underclay 5 a. Pleasantview sandstone 0-50 + Suite IV. h. Gray shale 0-1 g. Dark limestone, concretionary y 2 ± f . Gray shale with septarian calcareous concretions 5-10 e. Black laminated shale, concretionary 1 d. Soft gray shale (Francis Creek shale) 0-9 c. Colchester (No. 2) coal 1-2^ Pottsville formation b. Underclay, sandy 4-5 a. Sandstone or shale, concretionary locally 2-8 Suite III. c. Gilchrist shale 20-100 b. Undifferentiated sandstone, shale, underclay, and coal 10-20 a. Sandstone, with chert in base locally 0-25 Suite II. g. Gray shale 1-4 f . Shaly limestone 1-20 e. Hard blue limestone, locally nodular in upper part 1-3 d. Black laminated shale or soft clay, concretionary 0-4 c. Rock Island (No. 1) coal, with local parting 0-5 b. Sandy underclay 0-4 a. "Stigmarian" sandstone 2-7 Suite I. a. Undifferentiated sandstones, shales, and underclays, with thin beds of limestone and coal 50-80 + 50 ALEXIS QUADRANGLE POTTSVILLE FORMATION The name Pottsville was first applied to the basal conglomeratic series of the Pennsylvanian strata. 64 The name presumably was derived from the town of Pottsville, Pennsylvania. In Illinois it is used as a formation name for the lower part of the Pennsylvanian system, which consists principally of sandstones, shales, conglomerates, and underclays, and in which coal beds are few and of minor commercial value. Most of the Pennsylvanian rocks exposed in the Alexis quadrangle be- long to the Pottsville formation. The best exposures of the Pottsville strata occur along the tributaries of Edwards River and Pope Creek in T. 14 N., R. 2 W. (Greene Twp.) and T. 14 N., R. 3 W. (Mercer Twp.) and near Fig. 10. Workable bed of coal in Suite I of the Pottsville forma- tion, exposed in a gully near Pope Creek, SE. ^ SW. V\ sec. 33, T. 14 N., R. 2 W. (Greene Twp.). The coal bed is 27 inches thick. Henderson Creek in T. 12 N., R. 2 W. (Spring Grove Twp.) (PI. I). The maximum known thickness of the Pottsville formation in the quadrangle is 220 feet, as determined from borings in the SW. % NW. ]/ A sec. 8, T. 14 N., R. 2 W. (Greene Twp.). The Pottsville formation is subdivided into three suites and part of a fourth as follows : I — Strata below the "Stigmarian" sandstone ; II — Strata between the base of the "Stigmarian" sandstone and a marked unconformity 64 Piatt, "W. G., and Piatt, F., Report on progress in the Cambria and Somerset dis- trict of the bituminous coal fields of Western Pennsylvania; Part I, Cambria: Second 1 Geol. Survey of Pennsylvania, Report of Progress H H, p. xxvi, 1S77. POTTSVILLE FORMATION 51 ,^, rD +U~ T?™1^ TM„,^ /"\T~ 1\ 1. TTT Ci — x„ t~^ 8 6 6 The coal is also well exposed about a mile and a half farther east: 50 ALEXIS QUADRANGLE of tCP fo of ar< loi oc R. H m 2,' R between the base of the "Stigmarian" sandstone and a marked unconformity 64 Piatt, W. G., and Piatt, F., Report on progress in the Cambria and Somerset dis- trict of the bituminous coal fields of "Western Pennsylvania; Part I, Cambria: Second Geol. Survey of Pennsylvania, Report of Progress H H, p. xxvi, 1S77. POTTSVILLE FORMATION 51 above the Rock Island (No 1) coal; III — Strata between the unconformity above the Rock Island (No. 1) coal and the top of the Gilchrist shale; IV — Strata above the top of the Gilchrist shale. SUITE I STRATA BELOW THE "STIGMARIAN" SANDSTONE These strata, which constitute the lower part of the Pottsville forma- tion, are exposed at numerous places along Edwards River and the lower portions of its tributaries in T. 14 N., R. 3 W. (Mercer Twp.), and T. 14 N., R. 2 W. (Greene Twp.) ; along Pope Creek in sees. 32 and 33, T. 14 N., R. 2 W. (Greene Twp.) ; and along Henderson Creek in sec. 14, T. 12 N., R. 2 W. (Spring Grove Twp.). The strata consist of sandstones, shales, underclays, and thin beds of coal and limestone. (Geologic sections Nos. 3, 4, 5, 6, 8, 11, and 12.) The characteristics of the lower portion of Suite I in the Alexis quadrangle are not well known, as it is not exposed in this area. A coal bed 2 to 2^ feet thick, which is known from drill records to be 9 to 15 feet below the Rock Island (No. 1) coal in the vicinity of a mine in the SW. % sec. 32, T. 14 N., R. 2 W. (Greene Twp.), is locally persistent along the south bank of Pope Creek in sees. 32 and 33, T. 14 N., R. 2 W. (Greene Twp.) (fig. 10). Geologic section 3. — Composite of two outcrops along Pope Creek; NW. l /± SW. % sec. 32, T. 14 N., R. 2 W. (Greene Twp.) Thickness Feet Inches Pleistocene system 9. Loess and glacial drift (not measured) Pennsylvanian system Pottsville formation Suite II. 8. Sandstone, hard, cherty ("Stigmarian" ?) 2 Suite I. 7. Clay, underclay, white 4 6. Covered 6 5. Limestone, blue, hard, evenly bedded, sparingly fossiliferous. 8 4. Coal, fairly hard 2 6 3. Underclay, sandy, gray ; lower part blue-gray , 5 6 2. Clay, sandy, gray 4 1. Shale, blue-gray, containing ironstone concretions 9 The coal is also well exposed about a mile and a half farther east : 52 ALEXIS QUADRANGLE Geologic section 4. — Outcrop on the south side of Pope Creek and in an adjacent gully about 200 yards southeast of the middle of sec. 33, T. 14 A 7 "., R. 2 W . (Greene Twp.) Thickness Feet Inches Recent and Pleistocene systems 20. Soil and glacial drift (not measured) Pennsylvanian system Pottsville formation Suite III. 19. Sandstone, gray to olive-gray, micaceous, medium to mas- sively bedded ; contains traces of fossil roots, possibly Stigmaria, and some carbonaceous matter ; becomes shaly and finely laminated at base 5 10 18. Coal \y 2 17. Clay, sandy, purplish-gray 4 16. Clay, sandy, gray, blocky fracture, rusty ; contains impres- sions of fossil roots 2 15. Clay, gray to yellowish-gray, blocky fracture ; becomes lam- inated at base 2 6 Suite II. 14. Shale, blue, thinly bedded; contains oval, flattened concre- tions of gray limestone 4 2 13. Coal (Rock Island No. 1) 5 12. Clay, sandy, dark gray, somewhat laminated, micaceous 5 11. Clay, sandy, gray; contains impressions of fossil roots and lenticular streaks of carbonized material, probably roots ; locally grades into sandstone 8 to 10 inches thick, contain- ing Stigmaria; lower part laminated and basal 6 inches very rusty and apparently calcareous 6 Suite I. 10. Shale, dark blue-gray, soft, somewhat flaky ; contains "iron- stone" concretions and lenses of dark gray sandstone ; weathers to clay 6 6 9. Limestone, blue-gray, coarsely grained, fossiliferous, pyritic 10 8. Shale, abundantly carbonaceous, black to brownish-gray, soft 2 7. Coal 1 8 6. Underclay, very sandy, dark blue-gray, blocky ; derived from sandstone 1 3 5. Underclay, sandy, light gray, blocky fracture, derived from and grades down into sandstone; thickness varies accord- ing to amount of alteration of sandstone 2 6 4. Sandstone, light gray, blocky, contains Stigmaria 2 3. Sandstone, yellow-gray, hard, laminated ; contains Stigmaria and some carbonaceous matter ; some recrystallization of grains , . . . 2 2. Coal, dull, blocky, similar to cannel coal 6 1. Clay, light gray 10 POTTSVILLE FORMATION Other thin coal beds are present locally in Suite I in the northwest part of the quadrangle, especially in sees. 9 and 10, T. 14 N., R. 3 W. (Mercer Twp. ) . STRATIGRAPHIC RELATIONS The unconformity between the Pennsylvanian and older systems marks the base of Suite I (PI. II). An apparent angular and erosional unconformity occurs between Suites I and II, as the sandstones, shales, underclays, coal beds, and limestone layers which compose Suite I are frequently inclined where the overlying strata of Suite II are horizontal, as described below. Geologic section 5. — Outcrop in gully about 200 feet south of the center of sec. 3, T. 14 N., R. 2 IV. (Greene Twp.) Thickness Feet Inches Pleistocene system 18. Glacial drift (not measured) Pennsylvanian system Pottsville formation Suite III. 17. Clay, gray, dense 2 16. Sandstone, light-colored, hard, thin-bedded 2 Suite II. 15. Covered 2 14. Limestone, shaly, blue-gray ("Blue rock") 2 13. Limestone, dark blue, hard, containing Fusulinella sp 1 6 12. "Clod" 2 11. Coal (Rock Island No. 1) 2 8 10. Underclay 1 6 Suite I. 9. Sandstone, massive 1 6 8. Sandstone, thin-bedded 3 6 7. Sandstone, shaly, fine-grained 1 6. Sandstone, thin-bedded 8 6 5. Shale, gray 2 4. Calcareous nodules, elliptical in shape 3 3. Shale, light gray 11 2. Coal "blossom" V/ 2 1. Shale, sandy, dark gray 1 The strata numbered 10 to 17 are essentially horizontal, and those num- bered 1 to 9 dip 8° to the south (fig. 11). 54 ALEXIS QUADRANGLE Geologic section 6. — Outcrop in bank back of a barn 300 feet southeast of the middle of the west line of sec. 5, T. 14 N., R. 2 W. (Greene Twp.) Thickness Recent and Pleistocene systems Feet Inches 8. Soil and clay (not measured) Pennsylvanian system Pottsville formation Suite I. 7. Shale, soft, blue-gray 3 6. Coal ' 7 5. Shale, light gray 1 H 4. Shale, black, containing oval calcareous concretions 5 3. Underclay, light gray, containing calcareous concretions 3 2. Sandstone 2-0 1. Shale, gray-black, including band of 2-inch concretions 2 6 Fig. 11. Inclined sandstone beds of Suite I exposed in a small gully southwest of the center of sec. 3, T. 14 N., R. 2 W. (Greene Twp.). The sheet-like fragments of light colored rock on the left bank are derived from the limestone cap-rock of the Rock Island (No. 1) coal. All of the Pottsville strata dip approximately 4° southwest, but the "Stigmarian" sandstone which outcrops about 600 feet to the southeast is essentially horizontal. The same unconformable relations are also exposed POTTSVILLE FORMATION 55 (1) for some distance along the west bank of a large creek tributary to Edwards River, near the east edge of the NE. y A sec. 11, T. 14 N., R. 3 W. (Mercer Twp.), where the "Stigmarian" sandstone lies horizontal upon tilted beds of sandstone, shale, underclay, and coal belonging to Suite I ; and (2) on the north side of Henderson Creek, 250 yards west of the middle of the east line, of sec. 14, T. 12 N., R. 2 W. (Spring Grove Twp.), where the Rock Island (No. 1) coal lies horizontal upon 12 feet of sandstone contain- ing a 2-inch coal bed and dipping approximately 12° west. PALEONTOLOGY AND CORRELATION The blue limestone (geologic sections 3, member 5 and 4, member 9) is the only bed in Suite I that is known to contain marine invertebrate fossils (Appendix A). Plant impressions are found in some of the shale and sandstone beds. A specimen of Lepidodendron veltheimianum Sternberg, a Lepidodendron of distinctly Pottsville type, was collected from a massive sandstone exposed in a road-cut along State Highway Route No. 3 south of Edwards River, in sec. 9, T. 14 N., R. 3 W. (Mercer Twp.). The age of Suite I may be Middle or Late Pottsville. More complete fossil collections are needed before the age can be definitely determined. Suite I appears at the same horizon and is the equivalent of a series of Potts- ville strata in Fulton County which have been designated "Spoon River," 65 because they are well exposed along the river with that name. SUITE II. — STRATA BETWEEN THE BASE OF THE "STIGMARIAN" SANDSTONE AND THE UNCONFORMITY ABOVE THE ROCK ISLAND (NO. 1) COAL The strata comprising this suite represent approximately the middle portion of the Pottsville formation in the Alexis quadrangle and constitute a definite succession of beds that can be recognized in widely separated ex- posures, in contrast to Suite I. The complete succession of beds is (a) "Stig- marian" sandstone, (b) sandy underclay, (c) Rock Island (No. 1) coal, (d) laminated shale, (e) blue limestone, (f ) shaly limestone, and (g) shale (Pis. II and III). LITHOLOGIC CHARACTERISTICS The following geologic section describes the most complete exposure of the suite in the Alexis quadrangle (see also geologic sections 4, 5, 8, 10, 11, 12, 13, 14, and 16). 65 Savage, T. E., Significant breaks and overlaps in the Pennsylvanian rocks in Illinois: Am. Jour. Sci., vol. 14, p. 308, 1927. 56 ALEXIS QUADRANGLE Geologic section 7. — Outcrop in gully in the SE. % SE. 54 sec. 14, T. 12 N., R. 2 W. (Spring Grove Twp.) Thickness Feet Inches Pleistocene system 14. Clay (approximately) 5 Pennsylvanian system Pottsville formation Suite III. 13. Sandstone, shaly, thinly bedded, black to yellowish 7 6 12. Underclay (mostly covered) 6 6 11. Shale, carbonaceous, black (horizon of thin coal bed) 10 10. Sandstone, hard, containing Stigmaria 4 9. Sandstone, thinly bedded, soft 3 4 " 8. Chert .... 0-8 Suite II. 7. Shale, light gray, hard, silicified 1 5 6. Shale, calcareous, dark gray, rather hard 1 5. Limestone ("Blue rock"), shaly, blue-gray, slabb'y, splitting in broad thin plates, highly fossiliferous 3 6 4. Limestone, hard, nodular, with wavy lines of bedding ; blue- gray where fresh, weathering buff ; sparingly fossiliferous 1 2 3. Limestone ("Cap-rock"), slabby ; blue-gray where fresh, weathering dark gray ; contains Fusulineila sp 1 6 2. Shale, laminated, black, hard (miner's "slate") 4 1. Coal (Rock Island No. 1) (total thickness not exposed) (reported) 4 Not far from this exposure a thin gray, sandy clay underlies the coal in some places, and hard, massive, "Stigmarian" sandstone 2 to> 5 feet thick is present below the clay, or directly below the coal where the clay is absent. A succession of strata similar in sequence and thickness and at accordant levels with the above geologic section was revealed in a mine shaft on the south side of the road at the head of the same gully, in sec. 23, T. 12 N., R. 2 W. (Spring Grove Twp.). " Stigmarian" sandstone. — This member is designated the "Stigmarian" sandstone because siliceous casts of Stigmaria (the roots of Lepidodendron or Sigillaria) are particularly abundant in it. It varies in thickness from 2 to 5 feet, and in most places it includes 1 to 3 feet of thinly bedded, light- colored sandstone at its base and a single massive bed of very hard gray sandstone, 1 to 3 feet thick, in its upper part (fig. 12). This sandstone bed forms a small natural bridge over a creek in the SE. J4 sec - H> T. 14 N., R. 3 W. (Mercer Twp.), where the Rock Island (No. 1) coal outcrops at about the same level 300 yards farther north. POTTSVILLE FORMATION 57 Excellent specimens of fossil Stigmaria may be found in old mine dumps. Although Stigmaria fossils are abundant in this sandstone their presence in a sandstone is not sufficient evidence by which it may be correlated with the particular sandstone in this suite, as they commonly occur in many Penn- sylvanian sandstones. Fossils of marine invertebrates (Appendix A) are found in a sandstone, presumably the "Stigmarian" sandstone, cropping out below the Rock Island (No. 1) coal along Edwards River in sec. 29, T. 15 N., R. 1 W. (Richland Grove Twp.), about one mile north of the north line of the Alexis quadrangle. *£ -~ » Fig. 12. A resistant ledge of "Stigmarian" sandstone in sec. 11, T. 14 N., R. 3 W. (Mercer Twp.). Under clay of the Rock Island (No. 1) coal. — In some places in the Alexis quadrangle gray, sandy, slightly sulfurous clay occurs between the "Stigmarian" sandstone and the Rock Island (No. 1) coal. The clay is not known to exceed 4 feet in thickness, and in numerous exposures it is onfy 1 or 2 inches thick. It is well exposed at the entrance to a drift mine near the center of sec. 3, T. 14 N., R. 2 W. (Greene Twp.). Rock Island (No. 1) coal. — The Rock Island (No. 1) coal is so desig- nated because it is the principal commercial source of coal in the vicinity of Rock Island, Illinois. It varies from about 1 inch to 5 feet in thickness, but where it is typically developed it has an average thickness of 4 to A]/ 2 feet. It consists of an upper bench of hard shiny coal, 12 to 20 inches thick, 58 ALEXIS QUADRANGLE and a lower bench of somewhat duller and softer coal, 18 to 36 inches thick, which are separated by a bed of black carbonaceous shale in sees. 4, 5, and 6, T. 14 N., R. 2 W. (Greene Twp.). (PL HI.) A bed of clay 1 to 4 feet thick appears as a parting in the Rock Island (No. 1) coal along a road-cut 100 yards west of the center of the east line of sec. 11, T. 14 N., R. 3 W. (Mercer Twp.). Pyrite concretions occur either as concretionary layers at various levels or are scattered through the coal. In several mines a pyrite band 1 to 3 inches thick occurs a few inches below the top of the lower bench ; in other mines a pyrite band is in the lower part of the upper bench. Some pyrite and calcite are present along the faces of joints in the coal. In areas where only a few feet of limestone and shale intervene between the glacial drift and the Rock Island (No. 1) coal, wide solution cracks in the limestone cap-rock admit water to the coal, so that much white clay or sand has been washed in along minor faults or fissures in the coal bed and forms "clay seams", as the miners call them. The coal for a few feet on either side of these clay seams is much weathered. Fig. 13. Diagrammatic sketch representing variation in thickness of the Rock Island (No. 1) coal, the presence or absence and the variation in thickness of the over- lying laminated shale, the variations in the "cap-rock" and "blue rock' above, variable thickness and absence of underclay and underlying sandstone in Williams' mine, NW. V 4 NW. V 4 sec. 32, T. 14 N., R. 2 W. (Greene Twp.). Owing to the undulatory erosional surface on which Suite II lies, the altitude of the Rock Island (No. 1) coal varies greatly, as is evident in mine tunnels where the coal may be traced continuously for some distance. It may vary as much as 15 to 25 feet in a single mine. The coal is generally thicker in the depressions or "sloughs" than it is on the rises or "rolls" (fig. 13). Although the coal occurs in many separate basins, the sequence of strata in all of them is similar. Black laminated shale. — In most outcrops in the Alexis quadrangle a pasty, carbonaceous clay or "clod" 1 to 3 inches thick forms the root of the Rock Island (No. 1) coal, but in some mines and in a few outcrops where the coal has a thickness of three feet or more a hard, laminated, black, cal- careous and carbonaceous shale or "slate" 1 to 4 feet thick occurs in place of the "clod." The character and thickness of the roof of the coal varies BBi ■ ■ I ."V.r./V wm POTTSVILLE FORMATION 59 according to its relation to the depressions or "sloughs," and the rises or "rolls" in the coal. The "clod" is present over the coal in rises, where the shale is absent, but in the depressions black, laminated shale reaches an average thickness of 2 feet and a maximum of 4 feet. When exposed to the air the shale "caves" and the iron sulfide (pyrite or marcasite) in the shale changes to ferrous sulfate. Large spherical concretions or "niggerheads", composed of carbonaceous mud firmly cemented with calcium carbonate and iron sulfide, occur in the shale in some places where it is thick. Interruption of the even bedding of the shale where these concretions are especially numerous shows that they Fig. 14. Massive limestone cap-rock overlying the Rock Island (No. 1) coal near the center of sec. 3, T. 14 N, R. 2 W. (Greene Twp.). are of secondary development. The concretions were observed in mines and mine dumps in sees. 3, 4, 5, and 6, T. 14 N., R. 2 W. (Greene Twp.). Similar concretions have been reported 66 in sec. 14, T. 12 N., R. 2 W. (Spring Grove Twp.), but none are reported in the mines now being operated in that vicinity. The concretions are conspicuously developed in the J. Snell mine, sec. 6, T. 14 N., R. 2 W. (Greene Twp.), in some parts of which they make the roof of the coal hummocky. ,nal%l e ntoE g ^.%t° mo° fi Warren County: GeoL Survey of IIlinois ' vo1 - 4 ' Geolosy 60 ALEXIS QUADRANGLE Both the black laminated shale and the* hard concretions in it contain marine fossils (Appendix A). Many of the fossils in the shale are crushed and poorly preserved, but perfect fossil shells can be extracted from the concretions. The internal and external casts of the shells in the concretions ..k^LJw. ,% QS>W LEGEND A Shaly limestone C Nodular limestone B Typical cap-roek A Laminated shale Fig. 15. Limestone strata overlying the Rock Island (No. 1) coal in sec. 14, T. 12 N., R. 2 W. (Spring Grove Twp.). are frequently pyritized. Many species abundant in the concretions have not been discovered in the black shale and conversely a few forms characteristic of the black shale have not been found in the concretions. POTTSVILLE FORMATION 61 Limestone cap-rock. — An evenly bedded, dark blue or gray limestone, 10 inches to 3 feet thick, overlies the laminated shale above the Rock Island (No. 1) coal or rests directly upon the coal where the shale is absent (Pis. 11 and III, and fig. 13). The limestone weathers buff or brown and com- Fis LEGEND D Shale C Shaly limestone B "Cap-rock" A Rock Island (No. 1) coal 16. Limestone strata overlying Rock Island (No. 1) coal along the south wall of a creek near the center of sec. 5, T. 14 N., R. 2 W. (Greene Twp.). monly outcrops as a projecting ledge above the less resistant shale and coal below (fig. 14). It is a relatively pure limestone, much purer than the overlying shaly limestone, and a sample of it when dissolved in dilute hydro- chloric acid left only a small residue of argillaceous and ferruginous material. 62 ALEXIS QUADRANGLE including Bryozoa casts. The best exposures of this limestone in the north part of the quadrangle are near the center of sec. 3, T. 14 N., R. 2 W. (Greene Twp.). In the south part of the quadrangle it is best exposed in sec. 14, T. 12 N., R. 2 W. (Spring Grove Twp.), where a hard nodular limestone occurs immediately above typical cap-rock (fig. 15). Both the usual cap-rock and the locally developed nodular limestone are f ossiferous. (Appendix A.) A Fusulinella sp. occurs in the cap-rock at nearly all of its outcrops, but its abundance varies greatly. The small size of the fossils suggests that the fauna is a dwarf fauna. Shaly limestone ("Blue rock"). — A shaly limestone, blue-gray to white in color, ranging in thickness from 1 to 20 feet, occurs above the limestone cap-rock. The shaly limestone splits into plates a few inches thick and a foot or more in diameter. The lower beds are thick, hard, and calcareous ; the upper beds are thin and grade into calcareous shale (figs. 16 and 54). In a few exposures the upper beds of this series are buff-colored and chalky. The chalky phase is well shown at the entrance to an abandoned coal drift near the SE. corner SE. % SW. % sec. 14, T. 12 N., R. 2 W. (Spring Grove Twp.). Large specimens of marine fossils are found throughout the shaly lime- stone. (Appendix A.) They are somewhat more abundant in the lower, more massive layers than in the upper, shaly layers. The buff-colored chalky limestone is also fossiliferous, but it contains fewer species than are found in the other places. (Appendix A.) Most of the larger fossils have been crushed or flattened by the pressure of the sediments, but in some specimens traces of the original color markings are preserved. Shale. — At some places in the Alexis quadrangle the shaly limestone grades upward into a gray, nonfossiliferous shale which is never more than 3 feet thick except where the limestone members of the suite are absent (Geologic section 12). At some localities where the shale is overlain uncon- formably by a chert bed, the upper foot of the shale is hard and gritty as though it were cemented by silica which had filtered in from above. STRATIGRAPHIC RELATIONS The angular erosional unconformity that occurs between Suites I and II of Pottsville strata is mentioned above (pp. 53-55). The relief of the erosional surface was so great that the "Stigmarian" sandstone did not fill all the depressions, and the irregularities are reflected in the variation of thickness and altitude of the Rock Island (No. 1) coal, its overlying laminated shale, the limestone cap-rock and even the higher shaly limestone (Pis. II and III and fig. 13). The depressions appear to be old valleys or estuaries. POTTSVTLLE FORMATION 63 Suite II is separated from Suite III also by an erosional unconformity, as the basal strata of Suite III are in contact with nearly all of the members of Suite II at one place or another. COKRELATION Worthen in 1870 67 made the coal bed outcropping in the west bank of Spoon River near the village of Seville, Fulton County, the type of No. 1 coal in western Illinois. Subsequently the coal of Rock Island and Mercer counties was correlated with the No. 1 coal. 68 It has been recently contended that the Rock Island coal may be a correla- tive of No. 6 instead of. No. 1 coal, 69 in which case it would be Early Mc- Leansboro instead of Pottsville in age. This contention was based on the facts: (1) that the foraminifer Fitsulinella girtyi, called Girtyina ventricosa in former publications of the Survey and considered a reliable index fossil to the limestone cap-rock of the Herrin (No. 6) coal at the base of the McLeansboro formation in many parts of Illinois, was discovered in abund- ance in limestones above the Rock Island coal near the village of Andalusia, Rock Island County; and (2) that the succession of beds — "slaty" shale, argillaceous limestone, sandy shale, and sandstone — associated with the Rock Island Coal of Rock Island and northern Mercer County was closely similar to the succession near Buda and Sheffield, Illinois, where the coal has been considered the Herrin (No. 6) coal. 70 The Matherville coal in sec. 27, T. 15 N., R. 2 W. (Preemption Twp.), about one mile north of the Alexis quadrangle, has been correlated with the Herrin (No. 6) coal. 71 The large collections of fossils (Appendix A) which were gathered from excellent exposures of Pennsylvanian rocks along the tributaries of Edwards River, Pope Creek, and Henderson Creek in the Alexis quadrangle provided a study of the marine fauna more complete than had hitherto been made in this area. Comparison of the faunas with those from other areas in Illinois, Ohio, Kansas, Missouri, Arkansas, Oklahoma, and Texas show that : (1) Spirifer rockymontana is nowhere recorded above the Pottsville (or lower Allegheny) formations or their equivalents; and (2) the species Pro- 67 Worthen, A. H., Geology of Fulton County: Geol. Survey of Illinois, vol. 4, Geology and paleontology, p. 94, 1870. 68 Worthen, A. H., and Shaw, James, Geology of Rock Island County: Geol. Survey of Illinois, vol. 5, Geology and paleontology, p. 221, 229-232, 1873. 69 Savage, T. E., and Udden, J. A., Geology and mineral resources of the Edgington and Milan quadrangles: Illinois' State Geol. Survey Bull. 38C, pp. 3, 37, 1921; Bull. 38, pp. 115, 149, 1922. Culver, H. E., Pennsylvanian correlation in northwestern Illinois: Bull. Geol. Soc. Amer. vol. 35, pp. 321-328, 1924. , Coal resources of District III (Western Illinois) : Illinois: State Geol. Survey Coop. Mining Ser. Bull 29, pp. 16-17, 19-20, 1925. . Present status of correlation of Illinois coals: Illinois State Geol. Survey Rept. Inv. No. 14, 1927. 70 Culver, H. E., Coal resources of District III (Western Illinois): Illinois State Geol. Survey Coop. Mining Ser. Bull. 29, pp. 36-37, 1925. 71 Savage, T. E., and Udden, J. A.. Geology and mineral resources of the Edgington and Milan quadrangles: Illinois State Geol. Survey Bull. 38C, p. 46, 1921; Bull. 38, p. 158, 1922. 64 ALEXIS QUADRANGLE ductus nanus, characteristic of the Pottsville formation, has been reported only in Illinois and only from strata older than the shales and limestones above the No. 5 coal. Consequently the older correlation of the Rock Island coal in the Alexis quadrangle with the No. 1 (Pottsville) coal of Fulton County seems to be substantiated. The discovery of "Girtyina ventricosa 33 in the Rock Island district led to further investigation of its stratigraphic range. Fusulinidae closely re- sembling- this form in external appearance were subsequently found widely distributed in Pottsville, Carbondale, and McLeansboro strata in many parts of the State. A recent restudy 72 of Fusulina revealed that forms having similar external appearance, which were formerly identified as Girtyina ventricosa, have different internal structures and belong to different genera and species. The name Fusulinella girtyi has been restricted to those forms which were originally described as Girtyina ventricosa. Specimens of Fusulinidae from the cap-rock of the Rock Island coal in the Alexis quad- rangle have been identified 73 as two species of the genus FusulineUa, both different in internal structure from FusulineUa girtyi and probably both un- described forms. The wide stratigraphic distribution of the Fusulinidae and the occurrence of various specific forms in the Pennsylvanian strata vitiate the correlation of the Rock Island coal with coal No. 6 solely on the basis of the presence of such forms in the cap-rock. Abundant field evidence of an unconformity below the Rock Island (No. 1) coal, such as is assumed in adjacent areas, is found in the Alexis quadrangle. It is interpreted as occurring within the Pottsville formation, despite the fact that it is an angular as well as an erosional unconformity. Guide fossils have not yet been found to prove that late Carbondale or McLeansboro sandstones and coal beds overlap the earlier Pennsylvanian strata in any part of the Alexis quadrangle. All of the limestone beds in Suite I taken together are equivalent to the formation that has been designated the Parks Creek limestone in Fulton County. 74 SUITE III — STRATA BETWEEN THE UNCONFORMITY ABOVE THE ROCK ISLAND (NO. 1) COAL AND THE TOP OF THE GILCHRIST SHALE The normal succession of strata in this suite, which varies more than Suite II, is: (a) a basal sandstone; (b) a variable series of sandstones, underclays, shales, and thin coal beds, all of which may be members of several suites, into which this suite may be subdivided as a result of future investiga- tions in adjacent areas; and (c) a thick shale. 72 Dunbar, C. O., and Condra. G. E. The Fusulinidae of the Pennsylvanian System in Nebraska: Nebraska Geol. Survey Bull. 2, 2d ser.. pp. 76-7S, 1927. 73 Identification made by Mr. Lloyd G. Henbest of the Illinois State Geological Survey. 74 Savage, T. E., Significant breaks and overlaps in the Pennsylvanian rocks of Illinois: Am. Jour. Sci. vol. 14, pp. 309-310, 1927. POTTSVILLE FORMATION 65 LITHOLOGIC CHARACTERISTICS The following geologic sections provide good examples of the suite (see also geologic sections 4, 5, 7, and 13-17). Geologic section 8. — Outcrop in the north-flowing creek in the SE. % sec - H> T. 14 N., R. 3 W. (Mercer Twp.) Thickness Feet Inches Pleistocene system 18. Loess and glacial drift (not measured) Pennsylvanian system Pottsville formation Suite III. 17. Shale, gray 18 16. Calcareous concretions, discoid 3 15. Shale, gray 2 14. Sandstone 4 6 13. Shale, gray 4 12. Sandstone, blue-gray, containing plant impressions 3 11. Shale, gray, containing "ironstone" concretions 2 6 10. Shale, gray 4 6 9. Underclay 2 8. Coal 3 7. Underclay 2 6. Sandstone, thinly bedded 2 Suite II. 5. Rock Island (No. 1) coal 8-10 4. Shale, gray 6 3. "Stigmarian" sandstone, hard 2 2. Sandstone, greenish-gray 2 Suite I. 1. Coal 6-8 Geologic section 9. — Road-cut south of North Henderson Creek, near the SE. corner sec. 20, T. 13 N., R. 2 W. (Suez Twp.) Thickness Feet Inches Recent and Pleistocene systems 12. Loess and drift 25 66 ALEXIS QUADRANGLE Thickness Feet Inches Pennsylvania!] system Pottsville formation Suite III. 11. Clay, dark blue-gray, slightly laminated: grades into sandy shale below 10. Shale, sandy, light gray, micaceous, thinly bedded : grades into sandstone below 9. Sandstone, light gray, micaceous, thinly bedded 8. Coal, weathered and soft 7. Clay, very sandy, dark purplish-gray, blocky fracture : con- tains traces of roots : probably derived from sandstone below 6. Sandstone, yellowish-gray, line grained, micaceous, lamin- ated: some traces of carbonaceous material and of roots.. 5. Limestone, ferruginous, weathered .into band of "ironstone'' concretions 4. Coal, weathered 3. Clay, slightly sandy, purplish-gray, block}- fracture 2. Clay, sandy, gray, blocky fracture Suite II. 1. Shale, dark blue-gray, thinly bedded: lighter gray in lower part Fig. 17. Pottsville strata cropping out along a gully in the center of the SW. % XE. % sec. 33. T. 14 X.. R. 3 W. (Mercer Twp.) The hammer marks the irregular contact of sandstone with a 5-inch bed of weathered coal (member 16. geologic section 11 s ) overlying gray underclay. 10-r POTTSVILLE FORMATION 67 Geologic section 10. — P ennsylvanian strata in sees. 20 and 21, T. 13 N., R. 2 IV. (Sues Twp.) 75 Thickness Pennsylvanian system Feet Inches Pottsville formation Suite III. 6. Coal trace 5. Sandsone, or sandy clay 15 Suite II. 4. Limestone, impure and shaly 1 4 3. Shale, blue-gray, arenaceous 6-12 2. Coal (Rock Island No. 1) 2 6± 1. Clay (underclay?), blue; partially exposed — Strata below member 5 of this geologic section are no longer exposed, but a few fragments of blue limestone (member 4), which were found near the old drift entrance, resemble the cap-rock of the Rock Island (No. 1) coal. Geologic section 11. — Outcrop in gully in SW. T /\ NE. 14 sec. 33, T. 14 N., R. 3 W. (Mercer Twp.) (Fig. 17) Thickness Feet Inches Pleistocene system 22. Loess and drift (not measured) Pennsylvanian system Pottsville formation Suite III. 21. Sandstone, yellowish, soft 4 20. Concretions, "ironstone," with septarian structure 10 19. Sandstone, yellow-gray, medium grained, fairly soft, loosely cemented, friable 2 6 18. Concretions, "ironstone," with septarian structure 2 17. Sandstone, yellow-gray, evenly bedded in beds 2-3 inches thick, basal surface slightly uneven ; ripple-marked and conglomeratic in a nearby gully 4 16. Coal S% 15. Underclay, dark gray 3 14. Underclay, sandy, gray, blocky fracture ; contains root im- pressions 1 10 Suite II. 13. Underclay, light bluish-gray, blocky fracture; contains some traces of roots at top ; bears smooth, blue-gray limestone concretions near base; contains layer of ironstone concre- 75 Green, H. A., Geology of Illinois, Mercer County: Illinois Geol. Survey vol. 4, p. 303, 1870. .68 ALEXIS QUADRANGLE Thickness Feet Inches lions with pisolitic structure ; underclay is probably from shale below 2 6 12. Shale, dark blue-gray; contains thin lenses of light gray sandstone interlaminated with blue shale 2 4 11. Shale, dark blue to black, thinly bedded 1 6 10. Coal (Rock Island No. 1), weathered 5 9. Underclay, sandy, purplish-gray 1 8. Sandstone ("Stigmarian") light gray to yellowish-gray, fine grained, massively bedded in upper part, slabby in lower part ; contains root impressions 4 6 Suite I. 7. Shale, sandy, blue-gray ; contains nodules of sand and small concretions of limestone or "ironstone" 2 6. Coal y 2 5. Underclay, purplish-gray, blocky fracture 1 1 4. Underclay, very sandy, blocky fracture 1 3. Shale, slightly sandy, blue-gray, blocky fracture 8 2. Covered (probably shale) 4 1. Shale, blue-gray, thinly bedded 10± Geologic section 12. — Composite of outcrops along ravine in W. Y? NW. ^4 sec. 22, T. 12 N., R. 2 W. (Spring Grove Twp.) Thickness Feet Inches Pleistocene system 20. Loess and drift 20-25 Pennsylvanian system Pottsville formation Suite III. 19. Clay, sandy, white to light gray ; may be derived from sand- stone below 2 18. Sandstone, white to light gray, fine grained, regularly bedded in beds % to 3 inches in upper part, massive bed near middle 4 17. Shale, sandy, micaceous, blue-gray, poorly bedded 3 6 16. "Ironstone" concretions, brown, fossiliferous 8 15. Shale, dark gray to black, laminated 1 14. Coal, undulatory 6 13. Underclay, very sandy, purplish ; thicker where coal is highest '5 12. Sandstone, light gray to purplish-gray, very fine grained, nodular, bedded, hard ; contains Stigmaria 1 6 Suite II. 11. Clay, very sandy, light gray to gray, blocky fracture; grades down into shale ; contains root traces 2 4 POTTS VILLE FORMATION 69 10. Shale, slightly sandy, gray to olive-gray ; weathering blue- gray 9. Shale, sandy, dark blue, well bedded; contains "ironstone" concretions « 8. Shale, black, soft 7. Coal (Rock Island No. 1) 6. Underclay, sandy, purplish-gray, slightly laminated 5. Underclay, slightly sandy, light gray, rusty on fracture surfaces, blocky fracture Suite I. 4. Clay, dark gray, blocky fracture ; grades down into shale . . 3. Shale, dark blue, thinly bedded 2. Sandstone, light gray to yellowish-gray, fine grained, slightly micaceous ; contains traces of carbonized plants, probably Stigmaria 1. Shale, slightly sandy, dark blue to black, fairly well bedded Thickness Feet Inches 68' 6" Fig. 18. Graphic log of coal-test boring in the NE. y A SE. J4 sec. 17, T. 14 N., R. 2 W. (Greene Twp.) showing complete sequence of strata between the Rock Island (No. 1) and the Colchester (No. 2) coals. 70 ALEXIS QUADRANGLE A shale bed similar to member 16 in the last geologic section and con- taining many "ironstone" concretions is exposed in the main forks of a large gully about a third of a mile southeast of Center School in the SW. % sec. 22, T. 12 N., R. 2 W. (Spring Grove Twp.). The concretions contain well preserved plant impressions which have been identified as follows: Sphenophyllum emarginatum (Brongniart)' Koenig, C alamo cladus equiseti- formis (Schlotheim) Schimper, Annularia sphenophylloides (Zenker) Gut- bier, Neuropteris rarinveris Bunbery, Neuropteris clarksoni Lesquereux, Neuropteris crenulata Brongniart, and Neuropteris fasciculata Lesquereux. A complete succession of strata between the Rock Island (No. 1) and the Colchester (No. 2) coals was also* penetrated by a coal-test boring made by the Alden Coal Company near the crossing of the Rock Island Southern Fig. 19. Massive, cross-bedded sandstone in the center of the NE. *4 NE. 14 sec. 7, T. 14 N., R. 2 W. (Greene Twp.). This sandstone is probably the basal member of Suite III or Suite IV and fills a channel cut into Suite II. Railway and the Chicago, Burlington and Quincy Railway, in the NE %. SE. y A sec. 17, T. 14 N., R. 2 W. (Greene Twp.)' (fig. 18). Basal sandstone. — The sandstone at the base of Suite III is cross-bedded and ripple-marked and contains an abundance of carbonaceous fragments. It is usually only a few (2 to 7) feet thick, but in some areas it is absent. At some localities a sandstone attaining a thickness of as much as 25 feet, as in a gully near the center of the NE. y A NE. ]/ A sec. 7, T. 14 N., R. 2 W. POTTS VILLE FORMATION 71 (Greene Twp.), where it fills a channel cut deeply into Suite II (PL II and fig. 19), may be the basal or a higher sandstone in Suite III or possibly the basal sandstone of Suite IV. Along the north side of Henderson Creek in the center of the E. y 2 sec. 14, T. 12 N., R. 2 W. (Spring Grove Twp.), a 3-inch bed of coarse-grained sandstone, containing abundant spines of Petrodus occidentalis and numerous teeth and dermal plates of other fish, overlies the shaly limestone above the Rock Island (No. 1) coal and is im- mediately overlain by a six-inch bed of sandstone in which carbonized frag- ments of wood are numerous. The sandstone cannot be always distinguished from the "Stigmarian" sandstone and other sandstone beds below the Rock Island (No. 1) coal where it rests unconformably on them. An irregular band of chert locally marks the base of the sandstone. The chert follows the line of the uncon- Fig. 20. Exposure of strata about 8 feet above the Rock Island (No. 1) coal in the NW. Y A sec. 24, T. 12 N., R. 2 W. (Spring Grove fwp.). The 8-inch band of chert (C) separates the shale (B) and shaly limestone (A) ("blue rock") of Suite II below from the thin-bedded sandstone (D) of Suite III above. formity between Suites II and III and rests on the topmost shale, the shaly limestone, or the limestone cap-rock in Suite II. It is well, exposed at several outcrops in sees. 13, 14, and 24, T. 12 N., R. 2 W. (Spring Grove Twp.), where it is 8 to 12 inches thick (fig. 20), and on both sides of Pope Creek in the west part of sec. 32, T. 14 N., R. 2 W. (Greene Twp.). The following geologic sections exemplify the strata in this series, in- cluding the coal beds found near the base: 72 ALEXIS QUADRANGLE Geologic section 13. — Outcrop in a gully 200 yards south of old Pleasant Valley mine, in the SW. Y A SE. % sec. 4, T. 14 N., R. 2 W. (Greene Twp.) Thickness Feet Inches Pleistocene system 8. Loess and glacial drift (not measured) Pennsylvanian system Pottsville formation Suite III. 7. Shale, gray 3 6. Sandstone, light-colored, containing charcoal fragments 4 5. Coal 6-10 4. Underclay 1 Suite II. 3. Shale, gray, blue-gray, or brown 6-8 2. Limestone, shaly ("Blue rock") 10 1. Limestone, blue ("Cap-rock'') 1 2 Fig. 21. A bed of shell marl in the lower part of Suite III, exposed in a small creek in the NW. y A sec. 24, T. 12 N., R. 2 W. (Spring Grove Twp.). It overlies a thin coal seam (marked by hammer) about 30 feet above the Rock Island (No. 1) coal, which in turn overlies underclay. Geologic section 14. — Gully belozv the Richardson Mine; NW. Y\ sec. 24, T. 12 N., R. 2 W. (Spring Grove Twp.) Pennsylvanian system Pottsville formation Suite III. 8. Sandstone, buff-colored, thinly bedded, containing abundant poorly preserved pelecypods ; grades down into sandy shell marl in which there are charcoal fragments (fig. 21).... 7. Coal Thickness Feet Inches POTtSVILLE FORMATION 73 Thickness Feet Inches 6. Underclay, sandy, light-colored 2 6 5. Sandstone, massive 7 4. Sandstone, thinly bedded 1 6 3. Chert, gray 7 Suite II. 2. Shale, siliceous, gray, hard 2 6 I. Limestone, shaly ("Blue rock") — The coal in the above section is reported to be two feet thick in an adjacent coal-test boring. Gilchrist shale. — This shale constitutes the greater part of Suite III as exposed in the eastern part of the quadrangle. It is micaceous in some beds, is blue-gray to greenish in color, and contains plant impressions irregularly distributed. Its thickness varies from 20 to 30 feet to more than 100 feet. Its complete thickness is penetrated by a coal-test boring (fig. 18) near Gilchrist, sec. 17, T. 14 N., R. 2 W. (Greene Twp.), for which reason the name Gilchrist is here proposed as a designation for the shale. The shale is well exposed in the pits of the Hydraulic Press Brick Company at Shale City, sec. 8, T. 14 N., R. 2 W. (Greene Twp.), and of the Northwestern Clay Manufacturing Company at Griffin, sec. 4, T. 14 N., R. 1 W. (Rivoli Twp.) : Geologic section 15. — Pit of the' Hydraulic Press Brick Company at Shale City, sec. 8, T. 14 N., R. 2 W. (Greene Twp.) Thickness Feet Inches Pleistocene system 16. Loess 14 15. Till (Illinoian) 7 Pennsylvanian system Carbondale formation ? ' Suite IV? 14. Shale, slightly sandy, greenish-gray, finely laminated ; con- tains "ironstone" concretions 12 13. Shale, blue-gray 2 12. Clay, brownish, containing plant impressions \]/ 2 II. Coal, weathered (Colchester No. 2?) 4-8 Pottsville formation 10. Shale, dark, containing plant impressions 2 9. Coal y 2 8. Shale, dark gray, containing poorly preserved plant impres- sions 3 7. Shale, blue-gray, soft 8 6. Shale, sandy, blue-gray 7 74 ALEXIS QUADRANGLE Thickness Feet Inches 5. Sandstone, micaceous, yellowish, fine-grained 1 3 4. Shale, bluish, rather hard, laminated 11 3. Sandstone 3 Suite III. 2. Shale, micaceous, blue-gray, evenly bedded, thicker bedded and harder than shales above; occasional layers contain well-preserved plant impressions 27 6 1. Shale, greenish-gray, laminated and thinner bedded than overlying shale 6 Test borings in and near the pit penetrate immediately below the floor of the pit 80 feet of shale similar to that exposed in the pit. Geologic section 16. — Pits of the Northwestern Clay Manufacturing Company, sec. 4, T. 14 N., R. 1 W . (Rivoli Twp.), J4 m ^ e easi °f the Alexis quadrangle Thickness Feet Inches Pleistocene system 12. Loess and till (geologic section 27, p. 101) — Pennsylvanian system Pottsville formation Suite III. 11. Shale, gray, weathering to buff 10—15 10. Shale, blue ; contains scattered plant impressions, most abundant near base 20 9. Clay, calcareous, blue, hard, containing numerous gypsum crystals 2-4 8. Coal (local) 6 7. Underclay, gray 8 6. Underclay, white, and other rock 3± Suite II. 5. Limestone, shaly ("Blue rock") 11 4. Limestone, blue ("Cap-rock") 2 3. Rock Island (No. 1) coal 2 4 2. Underclay, sandy 1-0 1. Sandstone, irregularly bedded, pyritic — The foreman of the plant reported the character and approximate thick- ness of beds 1-6 as revealed in an abandoned drift mine. STRATIGRAPHIC RELATIONS At some localities the basal bed of Suite III rests with apparent con- formity on the topmost shale of Suite II, but in most places an erosional POTTSVILLE FORMATION 75 unconformity intervenes between the two suites (PL II). The best exposure of the unconformable relations is in a road-cut on the west side of a large ravine near the SE. corner NE. *4 sec - H, T. 14 N., R. 3 W. (Mercer Twp.). The magnitude of this unconformity is sufficient that the basal beds of Suite III may lie on any member of Suite II or even on some horizon in Suite I. This shows that various amounts of the upper part or all of Suite II were removed by erosion before Suite III was deposited. (Geologic section 8, p. 65.) Neither the Rock Island (No. 1) coal nor its overlying limestone, beds are present in many outcrops or are recorded in logs of test borings, and in some places the coal thins from four feet to a few inches or becomes completely absent within a lateral distance of a few hundred yards. For instance, the coal and associated beds outcrop at about the level of the bottom and within 200 yards of the Hydraulic Press Brick Company pit in sec. 8, T. 14 N., R. 2 W. (Greene Twp.), but they are entirely absent at the pit, as shale is reported for 80 feet below the pit. In at least two mines near the pit, the coal was reported to be "cut off by a fault". In the NE. % NE. ]/ A sec. 7, T. 14 N., R. 2 W. (Greene Twp.), within half a mile of the pit, a massive development of a cross-bedded sandstone occurs at the level of the Rock Island (No. 1) coal and associated beds. The unconformity in this position occurs also in the Edgington, Milan, and Avon quadrangles, 76 and elsewhere in western Illinois. An unconformity exists between Suites III and IV (PI. II). The re- lation between the Gilchrist shale and the Colchester (No. 2) coal is best shown along a gully tributary to North Pope Creek, north of the middle of sec. 26, T. 14 N., R. 2 W. (Greene Twp.). Geologic section 17. — Outcrops in a gaily in the SW. *4 NW. T /\ sec. 26, and SE. *4 NE. % sec. 27, T. 14 N., R. 2 W. (Greene Twp.) Thickness Feet Inches Pleistocene system 11. Loess and till — Pennsylvanian system Carbondale formation Suite IV. 10. Limestone, fossiliferous, containing septarian concretions that form a nearly solid ledge 8 9. Shale, dark gray, soft 2 8. Shale, black, hard, laminated, containing small calcareous concretions which give pitted or pimply appearance to bed- ding surfaces 2 7. Colchester (No. 2) coal 2± 76 Savage, T. E., and Udden, J. A., Geology and mineral resources of the Edgington- Milan quadrangles: Illinois State Geol. Survey Bull. 38C, pp. 49-51, 1921; Bull. 38, pp. 161-163, 1922. Savage, T. E., Geology and mineral resources of the Avon and Canton Quadrangles: Illinois State Geol. Survey Bull. 38B, pp. 22-23, 1921; Bull. 38, pp. 226-227, 1922. , Significant breaks and overlaps in the Pennsvlvanian rocks of Illinois: Am. Jour Sci. vol. 14, p. 311, 1927. 76 ALEXIS QUADRANGLE Thickness Feet Inches Pottsville formation 6. Underclay, white, containing a few silicified roots extending down from coal 5± 5. Shale, sandy, and sandstone, thinly bedded 2-5 Suite III. 4. Shale, gray, containing calcareous concretions at various levels 18 3. Shale, reddish 1 2. Shale, gray, containing large, flattened, ovoid concretions at some levels 21 ± 1. Sandstone, massive — PALEONTOLOGY AND CORRELATION Invertebrate fossils have been found only in the sandy marl roof of a thin coal near the base of the suite, in sec. 24, T. 12 N., R. 2 W. (Spring Grove Twp.) (Geologic section 14, p. 72). All of the pelecypod forms in the fauna appear to belong to one species, but the specimens are so poorly preserved that they can not be accurately determined. Fossil plants occur commonly in the shales at various horizons and are occasionally found in the sandstones. Fossil plants from the pit of the Hydraulic Press Brick Com- pany plant (members 2 and 10, geologic section 15), were identified as Sigillaria ovata Sanveur, Sigillaria brardi Brongniart, Pecopteris m-iltoni Artis, and Pecopteris vestita Lesquereux. Fossil plants from the pit of the Northwestern Clay Manufacturing Company (member 10, geologic section 16) were Sphenophyllum emarginatum (Brongniart) Koenig, Annularia radiata (Brongniart) Sternberg, Annularia sphenophylloides (Zenker) Gutbier, Stigmaria ficoides (Sternberg) Brongniart, and Neuropteris ovata Hoffman. These flora include few Pottsville types but are similar to the flora associated with the No. 2 coal of northeastern Illinois. 77 The basal sandstone of Suite III occupies the same stratigraphic position, and its' unconformable relations with Suite II are similar to those of a sand- stone in Fulton County, where the name Bernadotte was applied 78 to the member because it is well developed near the town of Bernadotte. The two members may be correlative. The rest of Suite III occupies the same strati- graphic position and has lithologic characteristics similar to those of a series of strata in Fulton County 79 which were designated by the name Avon, because they are well developed in the vicinity of the town of Avon. 77 Nof>, A. C, Pennsylvanian flora of Northern Illinois: Illinois State Geol. Survey Bull. 52, pp. 13-15, 1925, and personal communication. 78 Savage, T. E., Significant breaks and overlaps in the Pennsylvanian rocks of Illinois: Am. Jour. Sci. vol. 14, p. 309, 1927. 7a Idem. POTTSVILLE FORMATION 11 SUITE IV As only the lower two members of Suite IV occur in the Pottsville formation and most of the suite occurs in the Carbondale formation, the entire suite is discussed under the latter topic. UNDIFFERENTIATED POTTSVILLE STRATA The precise stratigraphic position of some Pennsylvanian strata exposed in the Alexis quadrangle can not be determined because their relations to recognizable horizons are not apparent. Most of such strata can be identified as belonging in the Pottsville formations. BASAL CONGLOMERATE Conglomerate composed chiefly of fragments of Burlington limestone and chert is exposed in a gully in the NW. *4 SE. J4 SE. 34 sec - 22, T. 12 N., R. 2 W. (Spring Grove Twp.), and along the south side of Maids Run at the west side of sec. 12, T. 13 N., R. 3 W. (Ohio* Grove Twp.), where rounded cobbles of chert and quartz are slightly cemented together. At the locality first cited the conglomerate lies on the Kinderhook shale and so marks the base of the Pennsylvanian strata. But it cannot be correlated either as the base of Suite I or with other basal Pennsylvanian beds, because the basal Pennsylvanian bed at any specific locality represents only the material first deposited along the margin of the Pennsylvanian sea as it submerged suc- cessively higher portions of the pre-Pennsylvanian land surface. Nor can such basal conglomerates be correlated with the beds of the same age deposited farther from the shores of the Pennsylvanian sea because the lithology of such beds differs radically. CONGLOMERATIC SANDSTONE A sandstone which is cross-bedded, exhibits ripple marks and raindrop impressions, and contains calcareous and "ironstone" concretions, and in- cludes two conglomeratic layers in which the fragments are Burlington lime- stone and chert, is best exposed in an old quarry in the W. V 2 sec. 19, T. 13 N., R. 2 W. (Suez Twp.) (fig. 22). Geologic section 18.— Old quarry in the W. V 2 SW. J A sec. 19, T. 13 N., R. 2 IV. (Sites Twp.) Thickness ™ • Feet Pleistocene system 6. Glacial drift (not measured) Pennsylvanian system Pottsville formation 5. Sandstone, heavy-bedded 3 4. Conglomerate, rather soft, weathered, containing- chert pebbles 1 3. Sandstone, massive 4 2. Conglomerate, as above 3 1. Sandstone, massive 5 78 ALEXIS QUADRANGLE This sandstone is probably in Suite I but may belong in one of the other suites. It is at approximately the same level as the coal (member 8, geologic section 9) two miles east. CARBONDALE FORMATION The Carbondale formation is so named because it is well exposed in the vicinity of the town of Carbondale in Jackson County, Illinois. 80 It com- prises the strata between the base of the Murphysboro (No. 2) coal and the Fig. 22. Sandstone exposed in an old quarry along the south side of North Henderson Creek in the W. y 2 SW. l /i sec. 19, T. 13 N., R. 2 W. (Suez Twp.). The bands marked "A" are conglomeratic layers. top of the Herrin (No. 6) coal, and consists of shales, sandstones, thin limestones, and most of the important coal beds of Illinois. It includes most of Suite IV and all of Suite V that is exposed in the Alexis quadrangle. 80 Shaw, E. W., and Savage, T. Herrin folio (No. 185), p. 6, 1912. E., U. S. Geol. Survey Geol. Atlas, Murphysboro- CARBONDALE FORMATION 79 B LEGEND h Shale, gray z g Limestone, dark, fossilifer- ous f Shale, gray, containing con- cretions e Shale, black, laminated 3' c Colchester (No. 2) coal b Underclay a Basal sandstone Fig. 23. Graphic representations of outcrops of Suite IV, Colchester (No. 2) coal and associated strata, in (A) NW. V A SW. Y A sec. 23, T. 14 N., R. 2 W. (Greene Twp.) and (B) center of the E. y 2 NE. Y 4 sec. 30, T. 12 N., R. 1 W. (Kelly Twp.). 80 ALEXIS QUADRANGLE SUITE IV. STRATA BETWEEN THE TOP OF THE GILCHRIST SHALE AND THE BASE OF THE PLEASANTVIEW SANDSTONE LITHOLOGIC CHARACTERISTICS The typical succession of strata in this suite is as follows: (a) sand- stone; (b) underclay; (c) Colchester (No. 2) coal; (d) gray soft shale (not always present); (e) black laminated shale containing concretions; (f) gray shale containing two or three levels of fossiliferous concretions; (g) dark, brownish, fossiliferous limestone; and (h) gray shale. (Fig. 23.) (Geologic sections 15, 17, and 19.) Geologic section 19.— Outcrop in gully, NW. % SW. J A sec. 23, T. 14 X., R. 2 W. (Greene Tzvp.) (Fig. 23A) Thickness Feet Inches Pleistocene system 12. Loess and till (not measured) Pennsylvanian system Carbondale formation Suite IV. 11. Shale, gray, soft 1 10. Limestone, brown, concretionary, very fossiliferous 5 9. Shale, gray, soft, containing flattened, septarian, fossiliferous, calcareous concretions at two or three horizons in lower « part 4 6 8. Limestone concretions, gray, septarian, fossiliferous, in gray fossiliferous shale 6 7. Shale, gray, soft 1 6. Shale, black, laminated, nodular, containing a few large calcareous and pyritic concretions and small calcareous concretions in which plant fragments are preserved 1 5. Colchester (No. 2) coal. hard, uniform, strongly pyritic 1 3 Pottsville formation 4. Underclay, strongly sulfurous. containing silicified roots .... 5 3. Underclay, sandy, containing hard, spherical, gray, septarian concretions 1 2. Sandstone, light, thinly bedded 8 Suite III. 1 . Gilchrist shale, gray, soft — The succession and thicknesses of the members of Suite IV vary con- siderably at different localities in the quadrangle (fig. 24). Sandstone. — The basal sandstone of Suite IV is known to be as much as 15 feet thick. It is well exposed in a gully in the NE. % SW. J4 sec. 1, T. 13 N.. R. 2 W. (Suez Twp.). where it is soft, thinly bedded, yellowish CARBOXDALE FORMATION SI Elevation in feet ■750 740 ■730 720 710 -70C 680 -670 660 I a !v.v! R 3 W. R 2 W. R. | W • 1 3. 7 1 »° e ?£* 4) \ 6 d = f c ; ' : ■W? / C b -:^-z- 4 ■°o -° , , Feet Inches Recent system 4. Soil, black 2 6 Pleistocene system Peorian series 3. Loess, leached, buff , 4 2. Loess, calcareous, gray 6 6 Sangamon series 1. Loesslike silt, noncalcareous 1 (to base of boring) lower calcareous zone, that is exposed along Farm Creek, east of Peoria. 103 It is known to be of Late Sangamon age, because it lies upon Illinoian gum- botil or upon erosion surfaces that truncate Illinoian till and Yarmouth sand. Peat beds assigned to the Sangamon series are reported in many areas adjacent 104 to the Alexis quadrangle. They were encountered at a depth of 20 feet in a coal-test boring near the center of the SW, y± sec. 32, T. 14 N., R. 2 W. (Greene Twp.). Legs reported at depths of 20 to 30 feet in many wells probably mark the Sangamon horizon. IOWAN AND PEORIAN SERIES The name Iowan was proposed for the fourth glacial series of the Pleisto- cent system because it has its best known expression in eastern Iowa. 105 The name Peorian was proposed for the subsequent interglacial deposits because they are best displayed in the vicinty of Peoria, Illinois. 106 A deposit of loess which covers nearly the entire Alexis quadrangle, including valleys, slopes, and uplands, represents Iowan and Peorian series. The loess is usually a fine, dustlike silt, composed of fine angular particles, but in some exposures near Mississippi River, stratified sand}' layers which are distinctly laminated are present. 107 No gravel or boulders are found in the loess itself. In the Alexis quadrangle the loess is in general uniform in texture, but stratified sand below or in the loess is noted in the following geologic section : 103 Leighton, M. M., The Farm Creek exposure near Peoria. Illinois — a typical Pleisto- cene section: Trans. Illinois State Acad. Sci. for 1925, vol. 28, pp. 401-407, 1925. Reprinted in Illinois State Geol. Survey Kept. Inv. No. 11, 1926. 1W Savage. T. EL, and Nebel, M. L., Geology and mineral resources of the LaHarpe and Good Hope quadrangles: Illinois State Geol. Survey Bull. 43, pp. 52-55. 1923. Savage, T. E., and Udden, J. A., Geology and mineral resources of the Edgington and Milan quadrangles: Illinois State Geol. Survey Bull. 38, pp. 173-174, 1922. Cady. G. H.. Geology and mineral resources of the La Salle and Hennepin quad- rangles: Illinois State Geol. Survey Bull. 37. pp. 73-76, 1919. 105 Chambeiiin, T. C. in Geikie. James, The Great Tee Age. pp. 753-764. 1S94. , The classification of American glacial deposits: Jour. Geol. vol. 3, pp. 270-277, 1895. ior Leverett, Frank, The Peorian soil and weathered zone: Jour. Geol.. vol. 6, pp. 244-249. 1898. 107 Savage, T. E., and Udden. J. A., Geologv and mineral resources of the Edgington and Milan quadrangles: Illinois State Geol. Survev Bull. 38C, p. 63, 1921; Bull. 38, p. 175, 1922. PLEISTOCENE SYSTEM 105 Geologic section 30. — Face of terrace remnant and auger boring along Pope Creek in the NW. Va NW. V A sec. 4, T. 13 N., R. 3 W. (Ohio Grove Twp.) Thickness Feet Inches Pleistocene system Peorian series 6. Loess, or loesslike silt, leached, light gray-brown, soft, crumbly 2 5. Loess or clay, light yellow -brown, more compact than above. 3 4. Clay, slightly sandy, becoming more sandy toward base 3 6 3. Sand, stratified, brownish at top, yellowish in lower portion, probably alluvial 3 6 2. Silt, strongly calcareous, blue-gray, probably alluvial 4 Sangamon series 1. Soil, black clay, with no pebbles 3 (to creek level) The loess normally includes two zones — an upper, oxidized, buff and yellow zone of which the upper part is leached and the lower part calcareous, and a lower calcareous, unoxidized gray zone. Gastropod shells are found in some exposures and irregularly shaped lime concretions ("loess-kindchen") are usually present in the calcareous loess. No recognizable fragments of plant debris have been found in the loess in this quadrangle. In road-cuts or stream-banks the loess stands in vertical or nearly vertical faces. It is, however, slightly less resistant to erosion than the underlying Sangamon silt and is slightly more dissected where both are exposed. (Fig. 37.) Fossils from the Peorian loess x indicates presence at specified localities : (1) Road-cut a little south of the center of sec. 9, T. 14 N., R. 3 W. (Mercer Twp.). (2) Gully south of Henderson Creek in NE. % sec. 12, T. 12 N., R. 3 W. (Sumner Twp.). (3) Pit of the Northwestern Clay Manufacturing Company, at Griffin, sec. 4, T. 14 N., R. 1 W. (Rivoli Twp.). 1 2 3 Polygyra thyroides ( Say) x Succinea ovalis pleistocenica Baker x x x Succinea grosvenori gelida Baker x x x Gonyodiscus shimekii (Pilsbry) x x x Vitrea hammonis ( Strom) x Vertigo ventricosa Morse x Vertigo modesta Gould x x Hendersonia occulta ( Say ) x x x Cochlicopa lubrica (Mull.) x Helicodiscus parallelus (Say) x Columella alticola (Ingersoll) x x Galba parva Say x . . 106 ALEXIS QUADRANGLE Geologic sections 21 to 30 inclusive, show that the loess is normally from 6 to 20 feet thick in the Alexis quadrangle and that the leached zone is 5 to 10 feet thick. The calcareous zone is usually absent wherever the loess is less than 10 feet thick. In the Alexis quadrangle the loess rests unconformably on Sangamon, Illinoian, and Yarmouth series and on Pennsylvanian strata. The contact between the loess and the underlying Sangamon soil is not always sharp, and in some exposures a calcareous silt above grades into noncalcareous silt below. There is a sharp break between the loess and the Illinoian till or older beds. (Fig. 37.) A portion of the loess may be Wisconsin or post- Wisconsin in age, as the Bloomington moraine and other portions of the Wisconsin drift- plain are usually mantled with a thin deposit of loesslike silt. Recent System post-glacial deposits The post-glacial deposits include alluvial deposits in the valleys of the streams, slope wash on the steeper slopes, and some eolian dust or loess. Gravels, sands, and silts of alluvial origin are found along practically all of the streams, even in the small head branches of many ravines (PI. I). The alluvial valleys of the larger streams are from a quarter of a mile to half a mile in width (fig. 7, p. 27). Near the mouths of tributaries the larger valley-flats are veneered with sands, gravels, and silts washed in by these tributaries. Alluvial fans occur at the lower ends of many small gullies. Slope wash, consisting of sands or silts, mantles most of the lower slopes. The coarser materials, such as pebbles from glacial drift, remain on the upper slopes and may cover the surface. Slump and landslide deposits are common on the steeper slopes. Soils have been developed on the surface of the uplands, slopes, and valleys. CHAPTER IV— STRUCTURAL GEOLOGY Introductory Statement Structural geology is the phase of geologic science that treats with the determination of the attitude of rock strata and the interpretation of struc- tural features as related to earth movements. In regions where there are abundant outcrops, the rock structures may be determined with considerable accuracy by actual measurements of the amount and direction of dip or slope of the rocks at numerous points or by an accurate survey of the location and elevation of outcrops of key beds. But in most of Illinois, as in many other regions, outcrops are so few that most of the structural data must be derived from records of wells and other borings. The absolute elevation of any key-bed penetrated in the borings may be easily ascertained if the elevation at the surface and the depth to the key-bed are known. The geologic structure in such regions may be best depicted by maps on which contours show the elevation of the key-bed (figs. 38, 39, and 40). Graphic representations of the position, elevation, and attitude of the strata (Pis. II, III, V, and VI) are desirable supplements to structure maps. Structural maps are of importance, not only because they reveal the nature and time of deformation, but also because they provide data by which it is possible to determine the depth to aquifers, the probable distribution of coal beds, and localities worthy of testing for oil and gas and other mineral resources. Data Used in Making Structural Maps of Alexis Quadrangle The data on structural geology for the Alexis quadrangle were obtained from outcrops and from the records of wells, mine shafts, and test-borings for coal and oil. The altitudes of the borings and of numerous outcrops of the Colchester (No. 2) and the Rock Island (No. 1) coals were determined by a planetable survey. The approximate altitudes of a number of coal-test borings that could not be accurately located were estimated from the topo- graphic map and except on steep slopes these approximations have a maxi- mum possible error of not more than 20 feet. As the records of coal-test borings were compiled by the drillers at the time of drilling, they are essen- tially accurate. The records of most of the wells were less carefully compiled. The datum points on which the structural contours are based are un- evenly distributed over the Alexis quadrangle (figs. 38, 39, 40). The strata 107 108 ALEXIS QUADRANGLE below the Pennsylvanian system are penetrated in such a small number of drillings in the Alexis quadrangle that their detailed structure cannot be Fig 38. Structure maps showing the elevations of four Paleozoic horizons for the area in and near the Alexis quadrangle. The boundary of the quadrangle is outlined. Datum, sea-level. Logs of wells are given in Appendix C. determined but the general structural features of the part of Illinois included between Rock Island and Moline on the north, Alpha and Woodhull on the STRUCTURAL GEOLOGY 109 east, Mississippi River on the west, and Monmouth and Galesburg on the south, are revealed by data from the drillings in the whole region. (See Pis. V and VI, and figs. 38 and 39.) Structural Features top of dresbach formation Reliable information regarding the elevation of this horizon is available at only six widely scattered localities in the region, so that its structure cannot be satisfactorily determined. As its elevation at Moline is 1399 feet below sea-level and at Monmouth it is 1576 feet below sea-level, a general south- ward slope is suggested. BASE OF ST. PETER FORMATION ; TOP OF ST. PETER FORMATION ; TOP OF GALENA FORMATION ; TOP OF MAOUOKETA FORMATION All of these horizons reveal essentially similar structure (fig. 38). A synclinal depression pitches easterly across the north part of the Alexis quad- rangle, and east of the quadrangle it merges with another synclinal depression that pitches northeasterly across the southeast corner of the quadrangle. The synclines are separated by a northeasterly pitching anticlinal elevation in the southwest corner of the quadrangle. A broad anticlinal elevation pitching south of east lies just north of the quadrangle and is separated from a narrow anticlinal ridge farther northeast by a narrow synclinal depression which pitches southeasterly. Thus the general slope in the region is easterly. The parallelism of the structures at all four horizons is noteworthy. The erosional unconformity that is known to exist at the base of the St. Peter formation is well revealed in the north part of the region, where the elevations in two wells only a few blocks apart in Rock Island are re- spectively 558 and 721 feet below sea-level. Likewise the elevations in two wells at Aledo are respectively 424 and 501 feet below sea-level. Similar great differences in elevation doubtless occur elsewhere in the region. The slight erosional unconformities that occur at the other horizons are insuf- ficient to reveal themselves on the maps. TOP OF NIAGARAN SERIES ; TOP OF DEVONIAN SYSTEM Datum points by which the elevation of these two horizons may be determined are much more numerous than they are for lower horizons, and consequently the contours can be drawn in more detail (fig. 39). The fea- tures revealed by the contours on both horizons are strikingly similar. A major depression opening southward occupies the southeast part of the Alexis quadrangle. A broad branch of this depression extends northeast, and a 110 ALEXIS QUADRANGLE very narrow branch extends northwest across the northwest corner of the quadrangle. Another large branch depression appears to exist southwest of the quadrangle and connects with the northwest branch by a narrow depres- sion. Short depressions extend from these depressions in the southwest corner and the north end of the quadrangle. An irregular dome occupies the southwest part of the quadrangle. A broad elevation exists north of the quadrangle, and probably another one exists east of the quadrangle. STRUCTURAL GEOLOGY 111 The interpretation of these features is open to question. The general aspect of the depressions suggest that they constitute part of a river system, in which case the surface is principally erosional. But the marked similarity of the two surfaces raises the question why river courses developed at the ends of two successive geologic periods should be so nearly identical, and sup- ports the theory of a structural origin of the features. However, the top of the Niagaran series at many of the datum points is assumed to be the base of the porous zone from which many wells derive water, and this porous zone may be actually in the Niagaran series, not at the top. It may be a porous zone developed by solution at the same time that the present surface of the Devonian system was developed by erosion, and consequently it may be only a reflection of that surface. PENNSYLVANIAN STRUCTURES STRUCTURE OF THE ROCK ISLAND (NO. 1) COAL The Rock Island (No. 1) coal in the north part of the Alexis quad- rangle has a very uneven surface (fig. 40). The elevation of workable coal for which records are available varies between 596 and 678 feet above sea- level, and lies in a number of small basins which are either entirely discon- nected or are connected only by very thin coal. The general structure of the coal appears to be comprised of domes separated by gentle depressions. A general northward dip toward the Matherville coal district, sec. 27, T. 15 N., R. 2 W. (Preemption Twp.), in the Milan quadrangle, is indicated near the northern margin of the quadrangle, especially in sees. 3, 4, and 5, T. 14 N., R. 2 W. (Greene Twp.), and sees. 34 and 35, T. 15 N., R. 2 W. (Preemption Twp.). A gentle eastward dip is indicated by a few drill records in sees. 23, 25, and 34, T. 14 N., R. 2 W. (Greene Twp.) and sec. 30, T. 14 N., R. 1 W. (Rivoli Twp.). This eastward dip probably carries the coal to such o a depth in an area of high surface altitude that it has not yet been penetrated in drilling. The highest area of the coal lies in the western part of T. 14 N., R. 2 W. (Greene Twp.) and the eastern part of T. 14 N., R. 3 W. (Mercer Twp.) and it is probable that west of this area the coal occurred at such high altitude that it was stripped away by post-Pennsylvanian erosion. A fault, along which a 4-foot bed of coal is reported to have ended abruptly, is reported by miners as extending from Wanlock in sec. 9 to Shale City in sec. 8, and perhaps also to the SW. T /\ sec. 6, T. 14 N., R. 2 W. (Greene Twp.). However, in outcrops near Shale City it appears that a sandstone fills a channel that cut through the coal and the "fault" may be only an abrupt erosional contact. None of the mines reported to extend to the fault surface were in operation at the time field studies were made. 112 ALEXIS QUADRANGLE In the south part of the Alexis quadrangle, the Rock Island (No. 1) coal lies near the western edge of the southern flank of an eastward plunging syncline (fig. 41). The altitude of the coal ranges from 609 to 657 feet. STRUCTURE OF THE COLCHESTER (NO. 2) COAL As the elevation of the Colchester (No. 2) coal can be determined at only 7 datum points in the north part of the Alexis quadrangle, its structure cannot be ascertained satisfactorily. The altitudes of this coal range from 713 to 750 feet, with a possible structural rise centering in the northeast corner of the quadrangle. STRUCTURAL GEOLOGY 113 In the southeast part of the quadrangle the Colchester (No. 2) coal lies on the south side of a synclinal basin plunging toward the east or southeast (fig. 41). The altitudes of the Colchester coal in this area range from 654 to 720 feet. MINOR STRUCTURAL FEATURES Minor faults or displacements that occur in the coal beds may be the result of uneven settling during the process of consolidation. Such faults are commonly exposed in mines and usually show displacements not exceed- ing one or two feet. The fault planes may be often detected by clay in the fissures. One small normal fault of this class is exposed in the west bank of the creek about 150 feet north of the west entrance of the shale pit of the Hydraulic Press Brick Company, in sec. 7, T. 14 N., R. 2 W. (Greene Twp.). R.2W. R.I W. II 12 7 8 • 14 13 I—- «£_ *S 16 •" • V^23 • • 24 y ->» >r.. Tjj*^ & Fig. 42. Minor faulting in lower Pennsylvanian sandstone, exposed in cut bank of creek in the NE. V A NE. ]/ A sec. 11, T. 14 N, R. 2 W. (Greene Twp.). i2m$* Fig. 43. A small overturned fold in the lower part of the Gilchrist shale, exposed in a creek bank west of the center of sec. 7, T. 14 N., R. 2 W. (Greene Twp.). The hammer lies along the axis of the fold, which is most easily traced by the concretionary layer above the hammer. CHAPTER V— GEOLOGIC HISTORY Introduction The geologic history of any area is recorded in the rock formations, the surficial deposits, and the existent topography of that area. The character of the rock formations, their attitude, and their relations reflect the conditions under which they were deposited and the alterations which they have sub- sequently undergone. From these data geologists are enabled to read the geologic history. Through all ages continental land masses have been sources of oceanic sediments. Gravel, sand, silt, clay, and mineral matter in solution have been transported, worked over and assorted, and deposited beneath the seas, the coarser material being generally deposited near the shore and the finer farther out. After consolidation by compaction and cementation, gravel becomes conglomerate, sand becomes sandstone, silt becomes siltstone, clay becomes shale, and chemical precipitates and organic secretions of calcium carbonate become limestone, or dolomite if mixed with magnesium carbonate. Cross-bedding, ripple and rill marks, channel fills, etc., record water movements, and together with sun-cracks, rain-drop impressions, and worm borings they record shallow-water conditions. Widespread limestone forma- tions indicate that the continents adjacent to the sea in which the limestone was deposited were low or distant ; coarse clastic sediments indicate that the continents were high or near the sea. Warped, folded, or faulted strata record earth movements. Erosion between two epoches of marine deposition is recorded by irregular contacts between the formations deposited during those epochs, by evidences of weathering in the upper part of the older formation, by residual detritus in the base of the upper formation, or by the occurrence in the younger forma- tion of fossils of organisms more advanced in their evolution than those in the older formation. The history of life development may be traced by the changes in life forms as revealed by the fossils in successively younger formations. The geologic history of Illinois is read partly from rock outcrops and partly from records of wells and borings and is supplemented by knowledge derived from similar data in adjacent regions. Similarly, the geologic history of the Alexis quadrangle as interpreted from the local bedrock formations which are exposed or are penetrated by borings may be supplemented by facts gleaned from studies of adjacent areas, because processes which were opera- 115 116 ALEXIS QUADRANGLE tive within the quadrangle were generally also operative over considerable areas outside. Pre-Paleozoic Eras An involved series of sedimentary periods interspersed with epochs of diastrophism, vulcanism, and igneous intrusion and separated by erosional epochs is recorded in the pre-Cambrian rocks where they are exposed. A similar series of events presumably occurred in Illinois during those eras. A long period of erosion, during which the pre-Cambrian peneplain that is known to occur in Wisconsin was developed, 1 immediately preceded the Paleozoic era. The present southward tilt of this peneplain surface may be due partly to its original slope, but it is probably due largely to subsequent diastrophic movements. Paleozoic Era The Alexis quadrangle lies within an era that is frequently designated as the Eastern Interior Basin. During the Paleozoic Era this basin was always a low-lying area and was frequently submerged by epi-continental seas. The alternate depression and elevation of the area relative to the level of the sea created alternate epochs of deposition and erosion, and the strand line changed radically many times and probably varied constantly in minor degree. The sediments deposited in the seas were derived from highland areas to the north in the vicinity of Lake Superior, from the Ozark highland area to the southwest, and sometimes from the Appalachian highland to the east. Some of the breaks in deposition reflecting changes in conditions are marked by discordant or unconformable strata, but others are marked only by a change of the fauna which is revealed by the fossils in the rocks. CAMBRIAN PERIOD The erosional interval that marks the close of the pre-Cambrian era apparently continued through Early and Middle Cambrian epochs in Illinois, as no formations of those series are known in the region. But in the Late Cambrian epoch the lowland surface was submerged and materials that now form the Croixan series were deposited. The fact that the series is thickest at the south and thins to the north suggests that the sea in which it was de- posited advanced from the south, and the off-shore phases that occur to the south show that the open sea was in that direction. The variable character of the rocks in the series show that conditions were neither stable nor pre- cisely the same over large expanses, although the formational divisions of the series which can be recognized in regular succession over wide areas show 1 Weidman, S., and Schultz, A. R., Water supplies of Wisconsin: Wisconsin Geol. and Nat. Hist. Survey Bull. 35, PI. I, 1915. Knappen, R. S., Geology and mineral resources of the Dixon quadrangle, Illinois State Geol. Survey Bull. 49, p. 34, 1926. GEOLOGIC HISTORY 117 that generally the gross conditions were similar. So many factors, such as the rate of weathering and erosion on land, in turn due to climatic conditions, diastrophic movements, amount of rainfall, et cetera ; the depth, extent, tem- perature, and clarity of the sea ; the relative position and configuration of the strand line; and the number and size of streams, enter into the conditions affecting sedimentation that the alteration of no one condition or set of condi- tions can be definitely ascribed as the cause of the change in character of rocks. The first deposits in the advancing sea were the sands that now form the Mt. Simon sandstone. The great thickness of the formation shows that conditions remained constant for a considerable time. Then conditions changed and the finer sediments of the Eau Claire formation were deposited. A recurrence of the earlier conditions brought about the deposit of the Dres- bach sands, to be followed in turn by deposition of the finer sediments of the Mazomanie-Franconia formation. The abundance of glauconite in the formation shows that there were then present some conditions not present during the other stages. Conditions changed only so as to be more favorable for the deposition of more calcareous sediments during the Trempealeau stage. Conditions favoring the deposition of sand recurred during the Jordan stage. In this region the Cambrian period was terminated by emergence of the land above sea-level, during which time the Madison and Mendota formations that occur in Wisconsin were completely eroded, if they had been deposited, in Illinois, and the Jordan formation was so eroded that only an irregular thickness of it remains. ORDOVICIAN PERIOD EARLY ORDOVICIAN EPOCH The Ordovician period was inaugurated by an invasion by the sea. This time the sea was clearer than during Late Cambrian time, for the sediments that were deposited were largely organic or chemical precipitates now com- prising the Oneota dolomite, as compared with the clastic deposits of the Croixan series. Then conditions changed and the sand that now composes the New Richmond formation was next deposited. A recurrent clearing of the sea again brought conditions favorable for the accumulation of limy muds, which now form the Shakopee dolomite. Ripple-marks, mud-cracks, and breccia in Shakopee dolomite exposed near Franklin Grove, Lee County, Illinois, indicate that it was deposited in shallow water and was frequently exposed on tidal flats. 2 An emergence of the whole region and a prolonged period of erosion terminated the Early Ordovician marine inundation. Relief of several hun- 2 Knappen, R. S.. Geology and mineral resources of the Dixon quadrangle: Illinois State Geol. Survey Bull. 49, pp. 82-85, 1926. 118 ALEXIS QUADRANGLE dred feet was locally developed 3 and in some parts of northern Illinois all of the Prairie du Chien series was eroded during this erosional interval, 4 but in other places a considerable thickness of the series is left. MIDDLE ORDOVICIAN EPOCH To open the Middle Ordovician epoch the sea again advanced over this area, which erosion had sculptured into hills and valleys. The valleys were first inundated and were filled either with coarse sediments, now forming conglomerate, in which chert fragments derived from the underlying dolo- mites are included, or with fine sediments probably representing soil material washed down the slopes and now forming shale. Eventually the entire sur- face was submerged, and in this sea the well-assorted, well-rounded grains of the St. Peter sandstone were deposited. The frosting and pitting of the sand grains show that before they were deposited in the sea they were much worn by the wind, probably in a desert bordering the ocean, 5 but marine fossils and the prevalence of horizontal bedding in the formation show that it is a marine deposit. . The St. Peter stage was closed by slight emergence which may have been only local in effect, as at some places there is an erosional unconformity between the St. Peter sandstone and the overlying formation and at pther places there seem to be transition beds, showing con- tinuous deposition from St. Peter to Glenwood stages. After a brief interval of erosion, conditions similar to those during the early part of the St. Peter stage recurred, as evidenced by the Glenwood sediments which consist of dolomitic sandstone and shale. Some unique environmental factor was present to cause the green color typical of the formation. Gradually conditions changed and lime mud free from sand was deposited. Organic life thrived in great profusion, and calcareous ooze, with occasionally a little mud, was the dominant sediment throughout Platteville and Galena stages. The calcareous deposits have been largely converted to dolomite by the addition of magnesium carbonate. As the Platteville forma- tion is thin-bedded and compact and the Galena formation is porous and thick-bedded, it is believed that the dolomitization of the Platteville limestone took place before its consolidation and that of the Galena dolomite may have taken place after consolidation. 6 The sea withdrew at the close of the Galena stage, and erosion and weathering prevailed for a time. 3 Fisher, D. J., Geologv and mineral resources of the Joliet quadrangle: Illinois State Geol. Survey Bull. 51, p. 20 and PI. Ill, 1925. 4 Thwaites, F. T., Stratigraphy and geologic structure of northern Illinois: Illinois State Geol. Survey Rept. Inv. No. 13, pp. 22-23, 1927. 5 Dake, C. L., The problem of the St. Peter sandstone: Univ. of Missouri School of Mines and Metallurgy Bull., technical series, vol. 6, No. 1, 1921. Lamar, J. E., Geologv and economic resources of the St. Peter sandstone of Illinois: Illinois State Geol. Survey Bull. 53, pp. 26-31, 192S. Knappen, R. S., Geology and mineral resources of the Dixon quadrangle: Illinois State Geol. Survey Bull. 49, pp. 89-90, 1926. GEOLOGIC HISTORY 119 LATE ORDOVICIAN EPOCH After an erosional interval, the sea again inundated the region, at which time conditions favored the accumulation of masses of silt, mud, and cal- careous debris that now compose the shales and limestones of the Maquoketa formation. Then followed an emergence with which the Ordovician period terminated. SILURIAN PERIOD ALEXANDRIAN EPOCH After an erosional interval of considerable duration, Illinois was largely submerged during the Early Silurian or Alexandrian epoch by seas which advanced from the Gulf of Mexico, 7 but there is no positive evidence that the Alexis quadrangle was submerged. It is possible: (1) that Alexandrian strata occur in the quadrangle and have not been distinguished from overlying' Niagaran strata; (2) that Alexandrian strata were deposited in the quad- rangle but were eroded during the interval between Alexandrian and Niagaran epochs; or (3) that the quadrangle remained a land area during the Alex- andrian epoch. The erosional unconformity that occurs between the Alexand- rian and Niagaran series at some localities in the State shows that there was an erosional interval between the two epochs, although at other localities there is apparent only a disconformity in strata and a notable difference in fauna to mark the interval. NIAGARAN EPOCH During the Middle Silurian or Niagaran epoch Illinois was again invaded by a sea, this time from the north or Hudson Bay region. Conditions favored deposition of calcareous ooze, which, like similar deposits in earlier seas, became dolomitized. The chert that is widespread in the Niagaran dolomites was formed in part by precipitation from circulating ground-waters sub- sequent to the consolidation of the sediments, and in part by direct chemical precipitation from the sea-water at the time of their deposition. 8 The Middle Silurian inundation was terminated by uplift of the area above sea-level. The Alexis, quadrangle was a land area during the Late Silurian epoch, at which time erosion and weathering proceeded. DEVONIAN PERIOD The land conditions existing during the Late Silurian epoch continued through the Early and Middle Devonian epochs. Erosion produced a local relief of as much as 50 feet, and at the same time weathering developed a porous zone in the upper part of the Niagaran series. At some places the 7 Savage, T. E., Silurian rocks of Illinois: Bull. Geol. Soc. America, vol. 37, pp. 513- 534, 1926. 8 Fisher, D. J., Geology and mineral resources of the Joliet quadrangle: Illinois State Geol. Survey Bull. 51, pp. 41 and 44, 1925. 120 ALEXIS QUADRANGLE Silurian system is so thinned by erosion that the entire remaining thickness is weathered, in which case the porous zone extends to the base of the system. During the Late Devonian epoch the sea reinvaded the Alexis quadrangle. Surficial residual fragments of Niagaran chert and dolomite were reworked and concentrated by waves and currents and deposited in the bottom of the sea. Thus a porous zone consisting in part of weathered Niagaran dolomite in place, and in part of detrital dolomite and chert in the base of the Devonian rocks occurs at the horizon between the Silurian and Devonian systems, and it is impossible to determine a precise contact between them. Drillers report the entire porous zone as a "blue sand". The Late Devonian sea invaded the Alexis region from the north con- temporaneous with the Tully sea invasion in New York State. The sea was comparatively clear, and the adjacent lands supplied little detrital material. Life flourished abundantly and locally coral reefs were developed. The cal- careous deposits which accumulated form the Wapsipinicon and Cedar Valley limestones. These formations have not been subsequently dolomitized, as were the limestones deposited earlier in this area. The sea withdrew again after the deposition of these calcareous sediments, and a long erosion interval followed, during which valleys 40 or 50 feet in depth were carved in some places, but in the Alexis quadrangle there is no evidence of erosion. MISSISSIPPIAN PERIOD In the early part of the Mississippian period the Alexis quadrangle was occupied by a sea in which dark muds containing numerous spores of Sporangites huronense (a lycopod plant of the fern group) were deposited. These muds have been consolidated into the Sweetland Creek shale. Their dark color and the presence of the spores suggest that they were deposited in a sheltered embayment. Deposition of muds apparently continued uninterruptedly from the Sweetland Creek stage through the succeeding stage, but the lighter, bluish- gray color and occasional fossils in the Hannibal shales show that the sea had become more open. During the Burlington stage the sea became clearer, so that the deposits were principally calcareous ooze. Marine life flourished. Some of the brachiopods became unusually large ; other brachiopods and crinoids became abundant and diverse, fragments of crinoid stems making up a large part of the Burlington limestone. Alteration of the limestone since its consolidation has produced layers and irregular nodes of chert, in which many of the fossils exist only as molds and casts, the shells having been dissolved. The Alexis quadrangle was probably occupied by the sea for a long time during the Mississippian period after the Burlington stage, as deposits of the Keokuk, Warsaw, Salem, and St. Louis stages occur only 40 to 50 miles GEOLOGIC HISTORY 121 south and once probably extended across the quadrangle. But if so, they were stripped away by erosion before the overlying Pennsylvanian strata were laid down, so that the time of the final withdrawal of the Mississippian sea from the Alexis area can not be determined. After the deposition of the latest Mississippian sediment in Illinois and before the deposition of the earliest Pennsylvanian there was considerable deformation. The La Salle anticline, the major structural feature of eastern and central Illinois, was uplifted and a basin which lay parallel to and south and west of the anticline, including the area of the Alexis quadrangle, was moderately depressed. A long erosion interval followed these movements. The younger Mis- sissippian sediments were completely stripped from the Alexis quadrangle, if they had been deposited. The Burlington limestone was left only in a small area near the southern margin of the quadrangle, where it forms an escarpment. A lowland several miles in width and covering most of the Alexis quadrangle was developed on the soft shales of the Hannibal and Sweetland Creek formations northward from this escarpment. A channel cut entirely through these shales to the Devonian limestone below exists along the east side of the quadrangle, and similar channels may have been cut in the northwest part of the quadrangle. All of the shales in the central west part of the quadrangle may have been eroded at this time. PENNSYLVANIAN PERIOD POTTSVILLE EPOCH The post-Mississippian erosion continued until the middle or latter part of the Pottsville epoch. Then the Alexis area was again invaded by marine waters, which inundated only the lowest portions of the lowland plain north of the Burlington limestone escarpment. The varied character of the first suite of Pottsville strata shows that conditions were not persistent over any considerable areas, that they differed greatly within short distances, and that they changed frequently. The deposition of the first Pottsville suite in the Hannibal-Sweetland Creek lowland was terminated by an interval of warping and uplift, followed by erosion which truncated the tilted beds. Upon the truncated beds sand, in which fragments of trunks, leaves, and roots of trees were included, was deposited by streams and slope-wash. The sand forms the "Stigmarian" sandstone. After the deposition of the sand, parts of the area became brackish-water or fresh water swamps, in which grew a luxuriant forest. The forest . debris developed peat, later changed into the Rock Island coal. Alteration processes prior to, contem- poraneous with, or since the plant growth changed the underlying material 122 ALEXIS QUADRANGLE to underclay. In a part of the swamp the accumulation of plant debris was interrupted by the deposition of a layer of mud. which now forms the clay parting in the coal. The mud appears to have been washed in from the northwest, because the clay parting thickens in that direction. Vegetable growth was then resumed and persisted until the next marine invasion killed the vegetation, which was buried under black carbonaceous muds. The cur- rents of the advancing sea mixed humus material and organic matter, derived from adjacent, deeply weathered land surfaces, with floating and suspended organic debris from the submerged forests to form sheets of black mud under which the peat was buried. Marine life, especially such mud-loving forms as gastropods and pelecypods. and swimming forms, such as sharks that fed on the molluscan life, invaded the area and contributed shells, teeth., and spines to the accumulating debris. Eventually the supply of land plant debris was exhausted, the water became clearer, and animal life flourished in greater abundance. Corals and crinoids. which can not exist in muddy waters, spread into the area, and the spindle-shaped colonial foraminifera (fusulinids) lived in such abundance that their shells make up a considerable part of the calcareous sediment which now forms the limestone cap-rock of the coal. Again the water became muddy, more clayey calcareous beds that now form shaly limestone ("blue rock") were laid down, and the character of the life gradually changed. Finally the calcareous material was no longer deposited, the water became more muddy, and the sea was no longer a suitable habitat for marine life. After deposition of the last mud. the region was drained of its marine waters for a short time, and streams cut channels over the area, locally cutting down to and even below the peat which now forms the Rock Island (No. 1) coal. Soon sand began to nil up these channels. At a much later time, after the sand had become partially consolidated into sandstone, silica carried in solution in circulating ground-water was precipitated along the contact between the sandstone and the less porous shale below, forming a band of chert which is widely associated with the base of the sandstone. After the channels were rilled with sand, marsh conditions again prevailed and lux- uriant forests again covered large portions of the area, in which areas the accumulating vegetable debris again formed peat beds which have been sub- sequently changed to the thin coal beds that lie about 20 feet above the Rock Island (No. 1) coal. Other portions of the area were occupied by wide lagoons in which the water was too deep for forest growth. In such lagoons and in the shallow sea which shortly occupied the whole quadrangle, including the south portion which had not been previously inundated, the hue silt and clay that now compose the Gilchrist shale was laid down. The water was not greatly disturbed In- waves, for the branches and even the fragile leaves of trees (ferns, club mosses, horsetails, et cetera) from nearby shores floated GEOLOGIC HISTORY 123 out and settled without serious mutilation to the bottom, where they have been preserved so well that the delicate venation of the leaves is retained. A third time the waters were again withrawn and streams again began to channel the surface. The period of emergence was shorter than that after the deposition of Suite II, as the underlying strata are less thinned by erosion and channeling is less pronounced. The period of active cutting was followed by another accumulation of sands until the channels were nearly filled and marsh conditions again prevailed. The return to marsh conditions marked the close of the Pottsville epoch. CARBONDALE EPOCH The Carbondale epoch began with a widespread marsh filled with a lux- uriant swamp vegetation. This marsh differed from those in which the Rock Island (No. 1) coal was accumulated in that it was continuous over hundreds of square miles in northern, western, and central Illinois, including the Alexis quadrangle. The rate of accumulation of vegetable debris in this marsh was so uniform that over wide areas the thickness of the Colchester (No. 2) coal formed from it varies only a few inches. The swamp may have spread into the Alexis area from the southeast, as the coal is thinner than in Knox and Fulton counties. The growth of vegetation and accumulation of peat was uninterrupted, as the coal has no bedded impurities, but it was terminated when the marsh was submerged by the sea. The sea was but little agitated, for stems and fragile leaves of trees floated out from forested shores and sank bodily to the floor of the sea, where they were buried in the soft, fine mud and silt that now forms the roof shales of the Colchester (No. 2) coal. The gray shale which occurs only locally either accumulated only in the lower parts of the submerged swamp or was removed by erosion from the higher portions. The origin of the black mud, which has since been compressed and consolidated to form the black laminated shale above the coal, can not at present be satisfactorily explained. It may be an ordinary mud deposited in stagnant or semi-stagnant water in which floating carbonaceous material, that became waterlogged and sank, decayed under the influence of bacterial action instead of being buried in mud. The vegetation from which the Col- chester (No. 2) coal was formed could not have been the source of carbon- aceous material for the black shale as the shale is in immediate contact with the coal only in small areas, and even in such places the coal shows no evi- dence of having been thinned by erosion. Furthermore, the black shale is nearly as widespread a formation as is the coal. The sand grains and leaf fragments that are commonly found in the small calcareous concretions in the shale were probably dropped from masses of floating vegetation. The fact that the papery laminae of the shale bend around the concretions makes it appear that the concretions were formed before the mud had become con- solidated. Conditions so changed after the deposition of the black mud that 124 ALEXIS QUADRANGLE succeeding deposits were lighter gray muds, some times calcareous, and marine life entered this region in abundance. For a short time, when the calcareous muds now forming the gray septarian limestone were precipitated, corals and crinoids occupied the area, but during the times when the water was more muddy, pelecypods, gastropods, ostracods, and worms constituted the dominant life. The alternation of limestones and shales is probably the result of widespread changes in conditions, as the succession of calcareous beds above black shale is similar over hundreds of square miles of western Illinois. The sedimentation was terminated by the withdrawal of the sea from the whole region. Again streams began to dissect the surface, cutting channels through the muds and calcareous beds of the last marine inundation, through the peat that became the Colchester (No. 2) coal, and even 30 or 40 feet lower. After a period of active erosion, the stream channels were filled by sand that now forms the Pleasantview sandstone. If any Pennsylvanian strata younger than the shale above the Pleasant- view sandstone were deposited in the Alexis quadrangle, they were com- pletely removed by erosion between the Pennsylvanian and Pleistocene periods. Post-Pennsylvanian, pre-Pleistocene Interval This interval includes the Permian period of the Paleozoic era, all of the Mesozoic era, and all of the Cenozoic era except the Pleistocene period. Since the withdrawal of the sea in late Pennsylvanian times the Upper Mis- sissippi Valley appears to have been a land area, subjected to continuous erosion and intermittent uplift so that at least two recognizable peneplains have developed. In southwestern Wisconsin and adjacent parts of Illinois, Iowa, and Minnesota (the district known as the "driftless area"), a high-level peneplain, called the Dodgeville peneplain, 9 possibly represents erosion to the Cretaceous period. Following uplift, this peneplain was largely reduced to another peneplain at a lower level, known as the Lancaster peneplain, 1 * so that by the Pliocene period the region stood in low relief with remnants of the Cretaceous peneplain rising above the general level. Mississippi River was the master stream of the Interior Province, but it flowed eastward from the vicinity of what is now Clinton toward the present position of the "big bend" in the Illinois River at Hennepin, whence it flowed south in a valley approximately followed now by Illinois River. The Alexis quadrangle was drained by preglacial streams that occupied the approximate position of the lower parts of Cedar Creek, Pope Creek, and Edwards River. A marked elevation of the land relative to sea level occurred at the close of the 9 Trowbridge, A. C, The erosional history of the driftless area, Pt. II: Univ. of Iowa Studies in Natural History, vol. 9, No. 3. pp. 55-127. 1922. 10 Grant, U. S., and Burchard, E. F., U. S. Geol. Survey Geol. Atlas, Lancaster- Mineral Point folio (No. 145), p. 10, 1907. GEOLOGIC HISTORY 125 Pliocene Period. As a result streams were rejuvenated and cut valleys into the Pliocene peneplain as much as 100 feet lower than the present valleys. Pleistocene Period World-wide climatic changes at the close of the Pliocene period caused snow and ice to accumulate over large areas in the northern hemisphere. These accumulations began as continental ice caps in the higher latitudes Fig. 44. Map of North America showing the centers of ice accumulation and the area of glaciation. but eventually increased in size and thickness and moved outward in all di- rections from the centers of accumulation. The continental glaciers which affected North America are known to have spread from three principal centers : ( 1 ) the Labradorean center, in the highlands of eastern Quebec and Labrador; (2) the Keewatin center, west and southwest of Hudson Bay; and (3) the Cordilleran center, in the Canadian Rocky Mountains. (Fig. 44.) The northern Mississippi Valley was invaded five times by 126 ALEXIS QUADRANGLE glaciers advancing from either or both the Keewatin and Labradorean centers, each invasion being followed by an epoch of milder climate during which the ice sheets melted away. (Table 1. p. 30.) The history of the Alexis quadrangle during the Nebraskan and Aftonian epochs cannot be determined, as there are no deposits of those series. KAXSAX EPOCH The first known glacial invasion of the Alexis area occurred during the Kansan epoch, when a glacier originating in the Keewatin center spread southward through central Minnesota and north-central Iowa into Missouri as far as the present valley of Missouri River and expanded radially eastward into Illinois, so that in the Alexis quadrangle it advanced from a westerly or even a southwesterly direction. As the glacier advanced, it incorporated within itself the soil that had been developed during the preceding emergent periods and also much of the underlying rocks in the areas over which it moved. Y\ nen the ice melted, this material was deposited as a heterogeneous mixture of clay, sand, gravel, and boulders. The clay, which consists not only of the older soil but also of material derived by the pulverization of most of the soft rocks and some harder rocks, serves as a matrix in which larger fragments of the harder rocks, both of distant and of local origin (boulder count, p. 95) are scattered. The dark color of the Kansan drift may be due to the large proportion of old soil that was picked up by the glacier. The Kansan epoch was terminated by ameliorated climatic conditions during which the ice melted away and with which the Yarmouth epoch was introduced. YARMOUTH EPOCH The Yarmouth interglacial interval, which was probably the longest of all the interglacial epochs, was marked through most of its time by a mild and humid climate in Illinois so that vegetation flourished, the Kansan till was deeply weathered, and the Kansan drift plain was extensively dissected by streams. Some of the Yarmouth drainage lines may be detected by the silt and sand deposited in their valleys. The largest Yarmouth valley in the Alexis quadrangle was near the present valley of Henderson Creek. It was locally two and one half to three miles in width, and its flood-plain was 35 or 40 feet lower than the present flood-plain of Henderson Creek. A smaller drainage line appears to follow the present valley of Goose Run rather closely. On flat or nearly flat surfaces where products of plant decay accumulated the soil waters were so acid that they dissolved or decomposed many of the pebbles and boulders in the drift, especiallv the calcareous rocks and the coarse-grained silicate rocks, and developed the gumbotil as a residual product. A dark soil was formed over most of the surface. Decayed vegetation ac- GEOLOGIC HISTORY 127 cumulated in bogs, as revealed by well drillings and by the common occur- rence of natural gas in wells 80 to 150 feet deep. ILLINOIAN EPOCH The long Yarmouth epoch was terminated by the recurrence of glacial conditions which inaugurated the Illinoian epoch. A glacier originating in the Labradorean center spread southwestward across Quebec, southern On- tario, and Michigan, and expanded radially in Illinois and Indiana, so that it advanced over the Alexis quadrangle from the east and southeast. Pebbles of jasper conglomerate from the Lorraine (upper Huronian) quartzite of the Cobalt district, northeast of Lake Huron in Ontario; and fragments of Burlington limestone from a few miles southeast of the Alexis area ; all of which occur in the Illinoian till, reveal the path that the glacier followed. Where the Illinoian glacier overrode Kansan drift, it mixed the upper weath- ered portion of the Kansan till so thoroughly with new material that the contact between the two drifts can seldom be distinguished in borings. Where the Illinoian ice moved over the soft Pennsylvanian shales it locally buckled them into sharp folds. The surface over which the Illinoian ice-sheet advanced was uneven, as a result of erosion during the long Yarmouth interval. Some of the Yarmouth valleys were completely filled by Illinoian drift, but many of the valleys, especially the larger ones, were only partially filled and are reflected in the present topography. The pre-Illinoian valley of Edwards River ap- pears to have been both wider and deeper than the present valley, because outcrops of pre-Pleistocene rocks are practically absent along the banks of the stream and for a few hundred yards up along the tributary valleys, beyond which Pennsylvanian strata are exposed at altitudes 50 to 75 feet above the present flood-plain of the river. The escarpment of Burlington limestone near the southern margin of the Alexis quadrangle was undoubtedly scoured by the ice and yielded numer- ous fragments of this rock which characterize the till in the southern portion of the quadrangle, but it protected the lowland north of the escarpment so that the weak, unconsolidated Yarmouth sands are preserved without con- tortion of the cross-bedding and other original structures. The recurrence of a milder climate caused the Illinoian glacier to melt away steadily and slowly. Its recession across the Alexis quadrangle must have been uniform, for there are no morainic ridges as would occur if there were halts. The complete absence of sand and gravel terraces along the streams indicates that the flow of water from the ice was not sufficient to carry sand and gravel, and this also suggests a slow melting of the ice. 128 ALEXIS QUADRANGLE SANGAMON EPOCH The Sangamon epoch was shorter than the Yarmouth epoch, shown by the fact that the Illinoian till was not weathered as deeply during Sangamon time as was the Kansan till during the Yarmouth epoch. As in the Yarmouth epoch, vegetation flourished, a rich dark soil was formed everywhere, gum- botil was developed on surfaces of low relief where the subsurface drainage conditions were poor, a reddish or rusty colored zone in the upper part of the drift was produced nearer the valleys of the larger streams where the subsurface drainage conditions were better, and stream erosion progressed. Although the main, westward-flowing streams of the area occupy valleys of pre-Illinoian origin, their larger tributaries occupy valleys carved chiefly during the Sangamon epoch. The slopes of the main stream valleys, which had been mantled with Illinoian till, were steepened by the lateral cutting of the meandering streams, and locally the Illinoian till was completely re- moved, as for instance on the south valley slope of Henderson Creek, where Late Sangamon deposits lie unconformably on Yarmouth sands. Remnants of low terraces that occur along Pope Creek in sees. 4 and 5, T. 13 N., R. 3 W. (Ohio Grove Twp.), and along Cedar Creek in sees. 20, 21, 22, 26, and 27, T. 12 N., R. 3 W. (Sumner Twp.), and that are covered in one case at least (geologic section 30 p. 105) by a black soil underlying calcareous silt, are interpreted as Sangamon in age and indicate that the valleys at that time were about the same as at present. On gently sloping upland surfaces the silt and clay content of the drift was washed out, so that the boulders and pebbles were concentrated on the surfaces and now underlie the late Sanga- mon loesslike silt or Peorian loess. In Late Sangamon time loesslike silt accumulated on the uplands, slopes, and valley floors. This deposit may have been calcareous originally, but if so it was entirely leached before the deposition of the overlying Peorian loess. IOWAN EPOCH The Sangamon interglacial epoch was terminated by a recurrence of conditions favorable for the accumulation of glaciers during the Iowan epoch. A glacier from the Keewatin center pushed southward through central Min- nesota into northern and central Iowa, where its terminal position was less than 100 miles northwest of the Alexis quadrangle, near the location of Iowa City, Iowa. 11 The climate in the Alexis quadrangle was probably so cold that erosion was materially retarded, but the only changes which may have occurred in the area during the Iowan epoch are a slight amount of erosion and weathering. The epoch was probably shorter than either the Kansan or the Illinoian epoch, as the Iowan drift is thinner and covers a "Alden, W. C, and Leig-hton, M. M., The Iowan drift; a review of the evidences of the Iowan stage of glaciation: Iowa Geol. Survey, vol. 26, pp. 49-212, 1917. GEOLOGIC HISTORY 129 smaller area than either of the others. At the close of the Iowan epoch the main, westward-flowing streams were lower in altitude than they are at present, the longer lateral tributaries were present but not as deeply en- trenched as they now are, the drainage system was simpler, and the inter- fluves were more extensive than at present. PEORIAN EPOCH Another epoch of milder climate, the Peorian, terminated the Iowan glacial epoch. In the early part of the Peorian epoch the wind picked up fine silt and dust from the surface of the exposed Iowan drift and from the valley-trains of streams which had served as glacial outwash channels and distributed it over wide areas where it completely mantled the uplands, the valley-slopes, and the flood-plains of streams beyond the area of Iowan glacia- tion. The distribution and character of the loess in the Alexis quadrangle and in the districts west and northwest of the quadrangle indicate that the source of the loess in these areas was primarily the flood-plain of Mississippi River, which drained extensive areas of both the Keewatin and Labradorean lobes of the Iowan glacier. The loess deposit smoothed and rounded the eroded Sangamon surface, filled the larger Sangamon valleys to a depth of ten to twenty feet, and forced these streams to change their work from valley- widening to down-cutting through the loess. Not all of the Peorian loess has yet been removed in some of the larger stream valleys. The loess contains numerous fossil shells of terrestrial or amphibious gastropods comparable with living species that inhabit damp, shady places, and feed on vegetation, and thus the conditions in the areas of deposition can be interpreted. 12 Although the loess may have accumulated so slowly that all vegetation completely decayed, its calcareous content shows that it accumulated faster than it could be leached. The calcium carbonate in the loess is mainly fine particles of limestone or other calcareous rocks ground up by the glacier. Loess accumulation during the Peorian epoch ceased when the Iowan till plain became covered with vegetation. . A brief period of weathering and soil formation 13 comprised the latter part of the Peorian epoch, the shortest of all the interglacial epochs. 12 Chamberlin, T. C, Supplementary hypothesis respecting the origin of loess of the Mississippi valley: Jour. Geol., vol. 5, pp. 795-802, 1897. Calvin, S., The Iowan drift: Jour. Geol., vol. 19, pp. 577-602, 1911. Shimek, B., Papers on the loess: Iowa Univ. Lab. Nat. Hist. Bull. 5, pp. 298-381, 1904 (and many other papers). Alden, W. C, and Leigrhton. M. M., The Iowan drift; a review of the evidences of the' Iowan stage of glaciation: Iowa Geol. Survey, vol. 26, pp. 140-164, 1917. 13 Leighton, M. M., A notable type Pleistocene section: — The Farm Creek exposure near Peoria, Illinois: Illinois! State Geol. Survey Rept. In v. No. 11, p. 5, 1926. 130 ALEXIS QUADRANGLE WISCONSIN EPOCH The brief Peorian epoch was terminated by a recurrence of glacial con- ditions, so that great ice-sheets once more formed in the three centers of accumulation. During this epoch Illinois was invaded only by a Labradorean glacier which advanced to a point a few miles west of Princeton, about 80 miles east of the Alexis quadrangle. In the Alexis area erosion and weather- ing were probably greatly retarded during this epoch. Some loess may have been deposited, but it cannot be distinguished from the early Peorian loess. Mississippi and Rock rivers were loaded with outwash material from the melting glacier and their valleys were considerably aggraded. As a result of this rilling in the Mississippi valley, the valleys of Pope Creek. Edwards River, and Henderson Creek were dammed and converted into lakes which may have extended up as far as the west part of the Alexis quadrangle. If any lacustrine silts were deposited, they have become weathered and indis- tinguishable from the Peorian and other loesses which had been deposited earlier in these valleys. Recent Period With the recurrence of a milder climate the Wisconsin glaciers melted away and the present period was initiated. The streams began to remove the tine, slack-water silt that had been deposited in their valleys, but they have not been able to widen their valleys since Sangamon time. They have de- veloped an intricate meander system unrelated to the earlier, larger, simpler meanders. The largest four streams in the quadrangle have not entirely cut away the Peorian loess in their valleys, and broad stretches of the deposit remain as terraces ten to fifteen feet above the present alluvial plains. The smaller streams, such as North Henderson and North Pope creeks, have removed the Peorian loess completely and are actively enlarging their valleys. The lateral tributaries of the large streams have also removed the Peorian loess, are cutting into the underlying Illinoian till and pre-Pleistocene rocks. and are working headward into the interrluves. Weathering of the surface materials, which was checked during the Wisconsin glacial epoch was resumed. The calcareous Peorian loess has been leached to depths of 6 to 10 feet. Soils have been developed. The accumulation of decaying plant material on the level interrluves and poorly drained flood-plains has there produced a black soil. The whole quadrangle was covered by vegetation — a prairie vegetation on the more level interstream divides and a forest vegetation on the slopes and on the bottom-land — which materially retarded surricial erosion. A large part of the local precipitation soaked into the soil instead of running off, and the flow of streams was more moderate and more permanent as the result of this subsurface supply of water. But since man occupied the dis- GEOLOGIC HISTORY 131 trict about 100 years ago and cut the forests and broke the sod, there has been more concentrated run-off with consequent gullying of the slopes (fig. 4), local development of bad-land topography (fig. 5), eventual abandonment of the fields, and the entrenchment of the smaller streams in narrow channels 10 to 30 feet deep below the older alluvial flats (fig. 6). Alluvial fans have been formed at the mouths of many of the smaller ravines. In a few places on slopes the finer silts are being removed, so that soils on the slopes are becoming more pebbly. Artificial drainage — the tiling of the upland flats and the straightening of the smaller streams — enables the water of heavy rains to reach the main streams more quickly and increases both the frequency and the degree of flooding of their alluvial plains. Coal mining has caused some subsidence of the surface at a few localities, thus altering the natural drainage, and creating a serious problem for land owners. CHAPTER VI— ECONOMIC GEOLOGY Mineral Resources The mineral resources of the Alexis quadrangle consist of coal, shale and clay,, sand and gravel, building stone, and water. Soil is also a very important economic asset. The possible occurrence of oil and natural gas is of interest. Coal Workable coal beds are scattered over all except the west side and south- west part of the Alexis quadrangle (fig. 45), which is included in Illinois Coal District III. 1 In the Alexis quadrangle the Rock Island (No. 1) coal is commercially important, and the Colchester (No. 2) coal, two Pottsville coals other than Rock Island (No. 1) coal, and two lenticular coals of un- certain age may eventually become so. The oldest mine in the quadrangle, located on the south side of Pope Creek in sec. 32, T. 14 N., R. 2 W. (Greene Twp.), has been in more or less continuous operation since 1861. There have been no shipping mines in operation in the quadrangle since 1920 al- though a shipping mine located at Matherville in sec. 27, T. 15 N., R. 2 W. (Preemption Twp.), about half a mile north of the quadrangle, was operating in 1926. Fifteen local mines exploiting the Rock Island (No. 1) coal were operating in 1926 (PI. I). ROCK ISLAND (NO. 1) COAL GENERAL STATEMENT Rock Island (No. 1) coal has been worked for many years in T. 15 N., R. 2 W. (Preemption Twp.), T. 14 N., R. 3 W (Mercer Twp.), T. 14 N., R. 2 W. (Greene Twp.), and T. 12 N., R. 2 W. (Spring Grove Twp.) (fig. 45). It varies notably in thickness, thinning from 4 or 5 feet to less than one foot or even disappearing completely within a quarter of a mile. In most mines only coal Zy 2 or more feet thick is mined (fig. 46). Conse- quently mining areas are isolated (fig. 45). The coal seam usually consists of an upper bench of bright, hard coal 12 to 20 inches thick and a lower thicker bench of duller coal (fig. 47). In mines in sees. 4, 5, 6, and 8, T. 14 N., R. 2 W. (Greene Twp.) the two benches are separated by a carbonaceous shale 10 to 18 inches thick. In a few mines about 6 inches of hard carbon- aceous shale, known as "false bottom", is found at the bottom of the coal. 1 Culver, H. E., Coal resources of District III: Illinois State Geol. Survey Coop. Min- ing Series Bull. 29, pp. 84-91, 115-120, 1925. 133 134 ALEXIS QUADRANGLE R. 2 W. Fig-. 45. Approximate areas from which the Rock Island (No. 1) coal has been mined out in the north part of the Alexis quadrangle. Solid lines indicate data from mine maps. Circles show wells or test borings that report the coal in workable thickness in unmined areas. Fig. 46. Rock Island (No. 1) coal in an old drift mine along south bank of Donahue Run, SF. y A NW. V A sec. 3, T. 14 N., R. 2 W. (Greene Twp.). COAL RESOURCES 135 A concretionary pyrite band 2 to 6 inches thick is found locally about 18 inches below the top of the coal. Small pyrite concretions are scattered irregularly through the coal. Chemical analyses (Table 2) show that the coal has a very high moisture content, high ash content, and nearly equal parts of volatile matter and fixed carbon. The volatile matter includes much carbon dioxide, which does not add to the heating value of the coal. It ranks as a low-grade bituminous coal. LEGEND 4 mm j-70 inches -GO 1 2 -50 -40 s -30 -20 -10 - ip s 1^ I Sandstone i 1 Clay Underday Shale Black shale Bony coal Coal S-Pyrite Fig. 47. Graphic representations of the Rock Island (.No. 1) coal. 1. Richardson mine, SW. % NW. % sec. 24, T. 12 N., R. 2 W. (Spring Grove Twp.). 2. Williams mine, NW. % NW. % sec. 32, T. 14 N., R. 2 W. (Greene Twp.). 3. Black Diamond mine, SE. % SW. % sec!. 2, T. 14 N., R. 2 W. (Greene Twp.). 4. Lillaman mine, NW. % SE. % sec. 4, T. 14 N., R. 2 W. (Greene Twp.). 5. Snell mine, SW. % SW. ^4 sec. 6, T. 14 N., R. 2 W. (Greene Twp.). Table 2. — Analyses of mine samples of coal No. 1 from the Alexis quadrangle and vicinity (Not exactly indicative of commercial output) Proximate analysis of coal 1st: "As ree'd" with total moisture 2nd : "Dry" or moisture-free Vola- Lab. File Date Mois- tile Fixed Ash Sul- co 2 B. t. u. Unit No. No.a ture Matter Carbon phur Coal Warrer> County 15416& 0224 7/26 154176 0224 (Mine average) 7/26 13.03 40.77 39.56 6.64 4.88 .04 11,583 Drv 46.88 45.49 7.63 5.61 .05 13,318 10.21 42.44 40.68 6.67 4.70 .05 11,946 Drv 47.27 45.31 7.42 5.23 .06 13.304 11.62 41.61 40.12 6.65 4.74 .05 11,764 Dry 47.08 45.40 7.52 5.36 .06 13,311 14,703 14,636 14.666 136 ALEXIS QUADRANGLE Vola- Sul- Lab. File Date Mois- tile Fixed Ash phur CO, B.t. u. Unit No. No.« ture Matter Carbon Coal Mercer County 13812c 1132 1/23 16.19 36.17 37.35 10.29 3.82 Tr. 10,428 Dry 43.16 44.56 12.28 4.56 Tr. 12,442 14,500 13813c 1132 1/23 16.49 36.97 38.63 7.91 3.13 .29 10,739 Dry 44.27 46.26 9.47 3.75 .35 12,860 14,448 13814c 1132 1/23 15.35 38.43 38.43 7.79 3.72 .11 10,945 Dry 45.40 45.40 9.20 4.39 .13 12,930 14,501 (Mine average) 16.01 37.19 38.14 8.66 3.55 .20 10,704 Dry 44.27 45.41 10.32 4.23 .24 12,744 14,483 1857c 1120 9/08 17.56 36.61 36.28 9.55 4.52 10,442 Dry 44.40 44.02 11.58 5.47 12,666 14,668 15414& 1102 7/26 16.38 37.80 38.96 6.86 4.35 .66 11,001 Dry 45.21 46.59 8.20 5.20 .79 13,156 14,608 15415& 1102 7/26 14.51 37.94 38.71 8.84 5.04 .68 11,024 Dry 44.38 45.28 10.34 5.90 .80 12,895 14,721 (Mine average 15.44 37.87 38.84 7.85 4.69 .67 11,012 last two analyses only) Dry 44.79 45.94 9.27 5.55 .80 13,024 . 14,660 5338^ C19 8/12 13.23 40.29 37.20 9.28 4.37 .41 11,104 0227a Dry 46.43 42.88 10.69 5.04 .47 12,797 14,641 5339d C19 8/12 15.24 37.66 35.73 11.37 4.80 1.47 10,353 0227a Dry 44.44 42.15 13.41 5.66 1.73 12,214 14,478 S340d C19 8/12 15.15 39.06 38.48 7.31 3.30 .17 11,252 0227a Dry 46.03 45.36 8.61 3.89 .19 13,260 14,760 5363d C19 8/12 14.97 38.27 37.07 9.69 3.75 .33 9,637 0227a Dry 44.99 43.61 11.40 4.95 .43 12,749 14,712 5364d C19 8/12 14.46 40.42 35.33 9.79 4.23 .69 10,780 0227a Dry 47.24 41.32 11.44 4.94 .59 12,603 14,551 5365d C19 8/12 14.07 39.95 34.01 11.97 4.55 .78 10,525 0227a Dry 46.49 39.59 13.92 5.29 .91 12,247 14,604 (Mine average) 14.52 39.26 36.32 9.90 4.16 .64 10,609 Dry 45.93 42.49 11.58 4.96 .72 12,411 14,349 5359<* C18 8/12 14.58 39.49 36.82 9.11 5.60 .15 10,894 0227 Dry 46.23 43.09 10.68 6.56 .18 12,754 14,642 5360<* C18 8/12 15.07 38.14 37.44 9.35 4.85 .34 10,790 0227 Dry 44.91 44.07 11.02 571 .38 12,705 14,618 5361^ C18 8/12 14.10 39.60 36.73 9.57 3.92 .23 10.956 0227 Dry 46.09 42.76 11.15 4.56 .27 12,753 14,660 (Mine average) 14.58 39.07 37.00 9.35 4.79 .24 10,880 Dry 45.74 43.31 10.95 5.61 .27 12,737 14,640 (Average Mercer County 15.64 38.51 36.89 8.96 4.44 .47 10,708 Coal Dry 45.65 43.73 10.62 5.26 .56 12,693 14,515 a Analyses having- the same file number are from the same mine. Analyses having filo number 0227 are from the Matherville district, just north of the Alexis quadrangle. b Samples collected by H. R. Wanless; analyses hitherto unpublished. c Samples collected prior to 1926 by members of the State Geological Survey; analyses hitherto unpublished. d Analyses published in Illinois Cooperative Mining Investigations Bull. 27. p. 8. 1923. COAL RESOURCES 137 The coal is immediately overlain by either 2 to 6 inches of sticky car- bonaceous clay, called "clod," or a hard, laminated, carbonaceous shale ("slate") which has a maximum thickness of about 3 feet. If thick enough, shale forms a good roof except near mine openings where it has been ex- posed to the air. Locally large calcareous or pyritic concretions are numerous in this shale and reduce its strength as a roof. Where the shale is thin it is removed with the coal. A massive blue limestone ("cap-rock") 8 to 24 inches thick overlies the shale and generally serves as an excellent roof. In some mines the limestone roof in rooms abandoned for sixty years has not fallen. Solution fissures in the limestone in some mines admit a large flow of water. "Slips," faults, and "rolls" occur in the coal in many mines. Clay seams follow some of the "slips" and faults, and the coal is weathered for a few feet back from these seams. Here and there much water gains access to the mines along minor faults. The coal generally lies on sandy clay which averages 6 to 8 inches in thickness and overlies a hard sandstone from which in some mines a good deal of water emerges. Locally the coal rests directly upon this sandstone. For additional data relating to specific mines, see Appendix B, Part III, pp. 173-176. UNEXPLORED AREAS PROBABLY UNDERLAIN BY ROCK ISLAND (NO. 1) COAL A large portion of Alexis quadrangle underlain by the Pennsylvanian rocks, in which coal beds of workable thickness may be present, has not been tested by drilling. Certain areas near and others more remote from transportation lines appear to merit the attention of anyone interested in determining the coal resources of the region. AREAS NEAR TRANSPORTATION Three areas along the Chicago, Burlington and Quincy Railroad between Aledo and Viola and one area east of Viola (fig. 47) are recommended for testing : (1) It is probable that the 4 feet of coal reported at an approximate depth of 110 feet with limestone "cap-rock" in sec. 14, T. 14 N., R. 3 W. (Mercer Twp.), continues along the railroad eastward into sec. 13, and into sees. 17 and 18, T. 14 N., R. 2 W. (Greene Twp.). (2) Coal may underlie the town of Viola in sec. 15, T. 14 N., R. 2 W. (Greene Twp.), as its presence is reported by Mr. B. McLaughlin of Viola, although it is not recorded in the log of the Viola city well. (3) Coal reported near the railroad in sec. 16, T. 14 N.. R. 1 W. (Rivoli Twp.), may extend north into sees. 9 and 4, along the spur of the railway from Hopewell to the Griffin shale pits, where coal was formerly mined at a depth of 60 feet. 138 ALEXIS QUADRANGLE (4) Coal of workable thickness reported in the SE. % sec - 14, T. 14 N., R. 2 W. (Greene Twp.) east of Viola indicates the probable existence of a body of workable coal within half a mile of the railroad southeast of Viola. AREAS REMOTE FROM TRANSPORTATION (1) Several test drillings and water wells show that the Rock Island (No. 1) coal underlies a large part of the southeast fourth of T. 14 N., R. 2 W. (Greene Twp.) and perhaps underlies adjacent portions of T. 14 N., R. 1 W. (Rivoli Twp.), at depths of 160 to 180 feet below the flat upland. Sees. 22, 23, 24, 25, 26, 27, and 34, T. 14 N., R. 2 W. (Greene Twp.), and sec. 30, T. 14 N., R. 1 W. (Rivoli Twp.), particularly deserve testing. (2) The coal bed (possibly Rock Island [No. 1] coal) discovered near New Windsor and mined in the Schuler Mine at Alpha, 2 Henry County, has been encountered in a number of wells west and southwest of New Windsor and may extend as a bed of workable thickness in the eastern tier of sections of the Alexis quadrangle, in T 14. N., R. 1 W. (Rivoli Twp.). Tests in this area should be sunk 200 feet or more below the upland plain, because the surface elevation rises toward the eastern margin of the quadrangle and the altitude of the coal declines. (3) The Henderson Creek area of the Rock Island (No. 1) coal may extend eastward into sees. 17 and 18, T. 12 N., R. 1 W. (Kelly Twp.), where coal is reported about 100 feet below the upland surface. (4) Deeper testing may reveal the Rock Island (No. 1) coal under parts of T. 13 N., R. 2 W. (Suez Twp.), and T. 13 N., R. 1 W. (North Henderson Twp.), where most wells obtain water from Pleistocene sands or Pennsyl- vanian sandstones and so are not satisfactory coal tests. Tests in the western tier of sections in Suez Township are not recommended, as the area is under- lain by marginal Pennsylvanian sandstones or conglomerates or by Devonian or Mississippian shales and no coal beds are reported. COAL BEDS BELOW THE ROCK ISLAND (xO. 1) COAL Thin coal beds which are known or believed to underlie the Rock Island (No. 1) coal are exposed in sees. 3. 9, 10, 11, and 12, T. 14 N., R. 3 W. (Mercer Twp.). and sec. 35, T. 15 N.. R. 3 W. (Perryton Twp.). Three such coals are exposed in creeks in sees. 9 and 10, T. 14 N., R. 3 W. (Mercer Twp.). They are thinner and more irregular than the Rock Island (No. 1) coal, as their thickness ranges from a few inches to 36 inches. The beds dip more steeply than does the Rock Island (No. 1) coal, and the character of the roof is more variable than that over the Rock Island (No. 1) coal. In general they are at present of no economic importance. Coal 24 inches 2 Culver, H E., Coal resources of District TIT, TUinois State Geol. Survey, Coop. Mining Series Bull. 29, p. 67, 1025. COAL RESOURCES 139 thick, apparently below the "Stigmarian" sandstone underlying the Rock Island (No. 1) coal, crops out in the bed of a creek in the NW. corner of the SW. ]/ A sec. 12, T. 14 N., R. 3 W. (Mercer Twp.). A well near the NW. corner of the SW. y A sec. 3, T. 14 N., R. 3 W. (Mercer Twp.), passed through the following strata: Geologic section No. 31.— Well near NW. comer SW. H sec. 3, T. 14 N., R. 3 W. (Mercer Twp.) Thickness Feet Inches Recent and Pleistocene systems 4. Loess and drift 16 Pennsylvanian system 3. Sandstone 13 2. Shale, blue 4 6 1. Coal 2 6 Near the SW. corner of sec. 35, T. 15 N., R. 3 W. (Perryton Twp.), a drift was driven on a coal bed only 2 inches thick in outcrop but 36 inches thick 50 feet from the entrance. This may be the Rock Island (No. 1) coal, but if so, the association of strata is unusual : Geologic section A T o. 32. — Drift mine near the SW. comer of sec. 35, T. 15 N., R. 3 W. (Perryton Twp.) Thickness Feet Inches Pennsylvanian system 5. Sandstone, light gray, massive, hard 2 4. Underclay, white 1 3. Shale, black, laminated 1 2. Coal 3 1. Shale, gray 3 A test-boring in sec. 8, T. 14 N., R. 2 W. (Greene Twp.), near the Shale City plant of the Hydraulic Press Brick Company, and near exposures of Rock Island (No. 1) coal at an altitude of 652 feet, encountered at an altitude of 541 feet, 1 foot 6 inches of coal under hard, gray shale. A relatively persistent coal seam, averaging 27 to 30 inches thick, under- lying blue limestone ("cap-rock") 11 inches thick, crops out along Pope Creek imsecs. 32 and 33, T. 14 N., R. 2 W. (Greene Twp.) (fig. 10). This coal lies 8 to 15 feet below and is locally more persistent than the Rock Island (No. 1) coal. It appears to be free from bedded impurities, and the roof appears to be satisfactory. There are one or two abandoned drifts in this coal. 140 ALEXIS QUADRANGLE COAL BEDS BETWEEN ROCK ISLAND (NO. 1) AND COLCHESTER (NO. 2) COALS Many test holes in the mining district south of Edwards River in Greene Township penetrated a coal 8 to 24 inches thick, 20 to 40 feet above the Rock Island (No. 1) coal. The roof of this coal is usually sandstone, but in a few places it is shale. The coal is not known to have a workable thick- ness at any place in the Alexis quadrangle. An 8-inch bed of coal underlying a sandy shell marl occurs about 20 feet above the Rock Island (No. 1) coal in sec. 24, T. 12 N., R. 2 W. (Spring Grove Twp.). (Fig. 21, p. 72.) A test boring in the same section encountered a 2-foot bed of coal at this horizon. This coal may be correlative with the coal near Edwards River. COLCHESTER (NO. 2) COAL The Colchester (No. 2) coal underlies parts of sees. 17, 23, and 27, T. 14 N., R. 2 W. (Greene Twp.), sees. 1 and 12, T. 13 N., R. 2 W. (Suez Twp.), and sees. 19, 20, 21, 29, and 30, T. 12 N., R. 1 W. (Kelly Twp.). In T. 13 N., R. 2 W. (Suez Twp.) and T. 14 N., R. 2 W. (Greene Twp.), the coal ranges from 15 to 30 inches thick, according to five records. It is soft, evenly textured, and without bands of pyrite or bedded clay. The coal is directly overlain by hard, laminated, black shale having a "pimply" concretionary structure (fig. 28). The shale would form an excellent roof for mines. The coal is underlain by soft, white underclay, in which silicified plant-roots may be found. In T. 12 N., R. 1 W. (Kelly Twp.), the coal ranges from 10 to 36 inches thick. (Fig. 24.) Where thickest it is separated from the usual hard, black, laminated shale roof by 2 to 9 feet of soft gray shale, which makes a poor roof. Small drift mines have been opened in this coal in a few places but no systematic mining has been attempted. Several drift mines have been abandoned because the soft shale caves so badly. At the present time the coal can be profitably mined only for local farm use. COALS OF UNCERTAIN STRATIGRAPHIC POSITION Two coal beds which occur respectively above and below the Rock Island (No. 1) coal are exposed in the west part of sec. 22, T. 12 N., R. 2 W. (Spring Grove Twp.), but are not known to occur elsewhere. The upper bed is 6 inches thick, and the lower one is 21 inches thick. MINING METHODS The room-and-pillar system of mining is employed in all mines, and entrance is gained by shafts and slope or horizontal drifts. The mine cars are moved by mules or men. Gasoline engines are used to hoist the coal in the larger mines ; in others mules are used for hoisting the coal. SHALE AND CLAY RESOURCES 141 Mine drainage is most difficult near the shaft. Water enters the mine from the sandstone underlying the coal, through solution openings in the overlying limestone, through faults or "clay-seams" and in some cases from abandoned rooms of old mines. The water is usually pumped out, but in a few mines it is hoisted in buckets under the cage. The bedded impurities are usually left in the mine, but the small, scattered concretions are separated after hoisting. Much of the coal is sold as lump or "block" coal to local farmers. Shale and Clay Shale and clay suitable for the manufacture of brick and tile occur in the Pennsylvanian and Pleistocene systems in the Alexis quadrangle. GILCHRIST SHALE The Gilchrist shale of Pennsylvanian age, which lies between the Rock Island (No. 1) and Colchester (No. 2) coals, is the only shale used at present for the manufacture of ceramic products. It is a thick, blue-gray, clay shale, generally free of sand. Calcareous concretions are scattered through the entire formation and are numerous at certain horizons. Formerly a number of ceramic plants exploited the Gilchrist shale, but at present only the Hy- draulic Press Brick Company and the Northwestern Clay Manufacturing Company are operating. Excellent exposures of the Gilchrist shale are found in gullies west of North Pope Creek in sec. 26, T. 14 N., R. 2 W. (Greene Twp.). A small kiln was once operated at this locality, and it is reported that white brick was produced from certain beds of the outcrop. Other good exposures of the Gilchrist shale where the overburden is thin are found in small valleys in sec. 33, T. 15 N., R. 1 W. (Richland Grove Twp.), not far from the Northwestern Clay Manufacturing Company plant at Griffin, and in the valley and tributaries of the large creek in sec. 7, T. 14 N., R. 2 W. (Greene Twp. ) , about a mile west of Shale City. CLAYS The clay below the Rock Island (No. 1) coal in the mines at Mather- ville, sec. 27, T. 15 N., R. 2 W. (Preemption Twp.), about one mile north of the Alexis quadrangle has been tested. The tests showed that certain parts of the underclay could be used to make common and face brick, but in general the samples were not sufficiently plastic to flow smoothly through a die and therefore much of the material was considered of doubtful value. 3 3 Stull, R. T., and Hursh, R. K., Tests on clay materials available in Illinois Coal Mines, Illinois State Geol. Survey Coop. Mining Series Bull. IS, pp. 75-79, 1917. 142 ALEXIS QUADRANGLE The same clay is found below the Rock Island (No. 1) coal in the Alexis quadrangle. The pebbles and boulders in the glacial drift make it unsuitable for ceramic purposes. It might be utilized for common brick and tile, but even for this purpose the pebbles and boulders would be troublesome. It is possible that the upper S to 10 feet of the loess, which is leached, could be used for the manufacture of common brick or tile. The lower part of the loess is usually calcareous and contains calcareous concretions, and it is therefore of extremely doubtful value for ceramic uses of any sort. Fig. 48. Typical exposure of the Gilchrist shale in the pit face of the Hydraulic Press Brick Company's plant at Shale City. A thin coal bed, Xo. 11 of geologic section 14, is indicated by lines. CERAMIC PLANTS HYDRAULIC PRESS BRICK COMPANY The plant of Hydraulic Press Brick Company is located at Shale City in the SW. corner NW. M sec. 8. T. 14 N.. R. 2 W. (Greene Twp.). The working face exposes about 40 feet of Gilchrist shale (fig. 48) overlain by SHALE AND CLAY RESOURCES 143 about 20 feet of glacial drift and loess. The shale and the drift are mixed in a ratio of two to one, so that stripping- is required only where the drift is more than half as thick as the shale. The shale includes a 4-inch band of coal and a 12-inch bed of fine-grained sandstone which are not separated. The blue shale which constitutes the lower 27^ feet of the working-face is reported to be the highest quality material. Shale of good quality is known to extend to a depth of 80 feet below the level of the present excavation. The plant produces a high grade face-brick. Horses draw the loaded cars to the plant, and the empty cars return by gravity to the working- face. The company operates 18 kilns (figs. 49 and 50). A one and a quarter mile spur to the Rock Island Southern Railroad provides transportation facilities. NORTHWESTERN CLAY MANUFACTURING COMPANY The plant of Northwestern Clay Manufacturing Company is located at Griftm, on the line between sec. 4, T. 14 N., R. 1 W. (Rivoli Twp.), and sec. 33, T. 15 N., R. 1 W. (Richland Grove Twp.) about a quarter of a mile east of the Alexis quadrangle. The Gilchrist shale is exploited at this plant, and is overlain by glacial drift and loess. (Geologic section 16.) An attempt some years ago to ex- ploit for ceramic purposes the loess, which is generally calcareous and con- tains numerous concretions, met with no success. A 5-foot bed of calcareous underclay lying below the shale was tested in 1926 for use in the manufacture of flue-tile. The results were not entirely satisfactory, but this was attributed to the fact that a band of highly siliceous material which occurs in the clay, w r as included. Additional tests of the underclay from which the siliceous bed will be excluded, are to be made. The underclay could be easily mined with the shale and from the floors of abandoned pits. The topography in the region in which this plant is located is undulatory, and the shale is quarried only at the terminal portions of spur-like ridges where the overburden is thinner. An area of about ten acres, involving a number of pits, has been worked in this fashion. The pit being worked 'in June, 1926, had a 20-foot face of shale and 2 feet of overburden. The shale is first stripped with a tractor and scraper, then it is blasted, and then loaded by hand into cars. Impurities, such as hard concretions, are picked out dur- ing loading. The loaded cars are drawn by horses to the plant. The com- pany operates 18 kilns (figs. 51, 52). The product is sewer-pipe, large sizes of drain-tile, wall-coping, and flue-tile. A 3-mile switch to the Chicago. Burlington and Quincy Railroad at Hopewell station provides transportation. MONMOUTH CLAY MANUFACTURING COMFANY A large pit near the NE. corner sec. 8, T. 14 N., R. 2 W. (Greene Twp.), about a mile northeast of the Hydraulic Press Brick Company pit. 144 ALEXIS QUADRANGLE Figs. 49 and 50. General view of the kiln, mill, and shale pits of the Hydraulic Press Brick Company at Shale City, sec. 8, T. 14 N., R. 2 W. (Greene Twp.). SHALE AND CLAY RESOURCES Figs. 51 and 52. General view of the kilns, plant, and two pits of the Northwestern Clay Manufacturing Company at Griffin, sec. 4, T. 14 N., R. 1 W. (Rivoli Twp.) and sec. 33, T. 15 N., R. 1 W. (Richland Grove Twp.). The pit shown in the upper view is an abandoned shale pit, the one shown in the lower view is a fire- clay pit. Note the piles of sewer pipe and drain tile, which are the chief products. 146 ALEXIS QUADRANGLE was formerly operated by Monmouth Clay Manufacturing Company. A face of 30 feet of Gilchrist shale, said to be of good quality, was worked. The shale was shipped over the Rock Island Southern Railroad to the company's plant at Monmouth. High cost of operation is assigned as the cause of abandonment of the pit. Sand and Gravel The Alexis quadrangle contains no extensive gravel deposits. Gravel, concentrated from the glacial drift, is found in the alluvial plains and bars of nearly all the larger stream valleys, but these deposits are so small that they are of value only for local use. Extensive deposits of pre-Illinoian sand are exposed on the south side of Henderson Creek, especially in sees. 3, 10, and 12, T. 12 N., R. 3 W. (Sumner Twp.) (fig. 33). The sand is loosely cemented, has a low clay content, and is stained yellow by iron oxide which may be largely removed by washing. A sieve analysis of a sample of this sand from a road-cut in the SW. >4 sec 3, T. 12 N., R. 3 W. (Sumner Twp.), is as follows: Sieve analysis of pre-Illinoian sand Per cent Retained on 10-mesh sieve Trace Passing 10-mesh, retained on 20-mesh sieve 11.9 Passing 20-mesh, retained on 40-mesh sieve 71.0 Passing 40-mesh, retained on 60-mesh sieve 14.0 Passing 60-mesh, retained on 100-mesh sieve 2.4 Passing 100-mesh sieve 0.7 100.0 The bulk of the sand is quartz grains, but small chert grains, some of them iron-stained, and other black grains are also present in small amounts. The grains vary in shape from sharp and angular to rounded. The rounded grains have frosted surfaces. The coarseness of the sand, its highly siliceous character, and its freedom from clay and calcareous material make it worthy of consideration for special uses such as sandblast sand, filter sand, engine sand, and molding sand where a coarse sand with high gas-venting properties is required. The valley of the large creek in the western part of sec. 12, T. 12 N., R. 3 W. (Sumner Twp.), where 30 feet of sand is known to occur locally, appears to be the best site for commercial exploitation of this deposit. The deposit is two and a half miles from the Rock Island Southern Railroad. Building Stone The building stone industry was at one time of considerable importance in the Alexis quadrangle. The massive Pennsylvania!! sandstones and the LIMESTONE RESOURCES 147 "blue rock" — a slabby, blue-gray, shaly limestone overlying the "cap-rock" limestone of the Rock Island (No. 1) coal — were formerly extensively quar- ried, 4 and the foundations' of many of the older farm buildings are of these materials. Quarries in the "blue rock" were located west of the Neverseen Coal Company mine in sec. 3, T. 14 N., R. 2 W. (Greene Twp.), (see fig. 53) ; near the local mine on the T. F. Mack farm, sec. 4, T. 14 N., R. 2 W. (Greene Twp.) ; and in sec. 34, T. 15 N., R. 2 W. (Preemption Twp.). Massive sandstones of quality suitable for foundations were formerly quar- ried in sec. 9, T. 14 N., R. 3 W. (Mercer Twp.), north of Aledo; in sees. 33 and 36, T. 15 N., R. 3 W. (Perryton Twp.) ; in sees. 26 and 34, T. 14 N., R. 2 W. (Greene Twp.) ; and in sees. 19 and 21, T 13 N., R. 2 W. (Suez Twp.) (fig. 31). Lack of demand caused abandonment of all these quarries. Large amounts of sandstone of satisfactory quality might be easily obtained. ?■<■', **••" " : ■ ■' ":"■■ ■ m s.."^-'.;*~... ■ -^'^... Iiii 13'v -IS' ' ' - ::;: .| ::' : .y- ? 1111 ill ~~ M <* : • ■ '•-earn.-* ^^BPW-BSP^ ^"m:S %,, e; ....,:«»-....._■ IS ■Mm, : .....^i « ■ .„.;... IE' ■-.:■'" -^ ^VjrlS::; - *' ■Will _. . J .-/rfc |lr " ~ - Fig. 53. Face of an old quarry in shaly limestone ("Blue rock") above the "cap-rock" of the Rock Island (No. 1) coal, in the NW. J /+ sec. 3, T. 14 N., R. 2 W. (Greene Twp.). Limestone Many years ago some of the "blue rock" was burned for lime. The product was fairly satisfactory, but it usually had to be screened lief ore using. 5 The Burlington limestone is a source for much rubble, lime, road metal, and agricultural limestone in many places in the State, but the single ex- 4 Green, H. A., Geology of Mercer County: Illinois Geol. Survey, vol. 4, pp. 307-308, 1870. 5 Green, H. A., Geology of Mercer County: Illinois Geol. Survey, vol. 4, p. 308, 1870. 148 ALEXIS QUADRANGLE posure of it in the Alexis quadrangle in sec. 30, T. 12 N., R. 2 W. (Spring Grove Twp.), is not thick enough toi be of any importance. Large quantities of it have been quarried a mile or two south of the quadrangle in sees. 32, 33, 34, and 35, T. 12 N., R. 3 W. (Sumner Twp.). Water Resources possible water-bearing formations CAMBRIAN SYSTEM The Mt. Simon sandstone and the Dresbach sandstone yield large quantities of water. The coarser layers which are the most prolific aquifers in the Mt. Simon sandstone are lenticular. The water from the Dresbach sandstone, which was designated formerly and is well known as the "Pots- dam" sandstone, usually has a smaller proportion of dissolved solids than that of any other water-bearing formation of wide distribution in northern Illinois. ORDOVICIAN SYSTEM Porous zones in the Prairie du Chien series are lenticular and do not usually yield much water. The St. Peter sandstone is an excellent aquifer but normally gives a somewhat smaller yield than the Dresbach sandstone, and the water usually contains a larger proportion of dissolved solids than the water from the Dresbach formation. Sulfates resulting from the oxi- dation of pyrite in the dolomites overlying the sandstone are sometimes present in large quantities in the water. Lenticular porous zones in the Platteville and Galena formations may yield much water, but commonly it is too highly charged with sulfates to be potable. Little or no water may be expected from the Maquoketa formation. SILURIAN SYSTEM The porous zone in the upper part of the Niagaran series yields a large quantity of water in all the wells which have been drilled to this horizon. It probably occurs under all of the quadrangle, and its approximate depth at any point may be determined from the structure contour map (fig. 39). The water is somewhat less mineralized than the water from the St. Peter sandstone. DEVONIAN SYSTEM The Devonian system yields very little water. One farm well obtains water from a porous zone near the top of the Devonian limestone. MISSISSIPPIAN SYSTEM The Sweetland Creek shale is almost without porous zones, and water is rarely obtained from it. A few farm wells near the southern border of Well number Appendix C and Plate IV Depth in feet Aquifer Depth of casing (feet) Gals, per minute yield Date sample was collected. Determinations made (Parts per million) Potassium a Sodium Ammonium Magnesium Calcium Iron Manganese q ii s sfcsrr WATER RESOURCES 149 the Alexis quadrangle get water from "soapstone" (shale) at a depth which indicates that the aquifer occupies a position near the base of the Hannibal or between the Hannibal and the Sweetland Creek formations. PENNSYLVANIAN SYSTEM The Pennsylvanian system includes many water-bearing sandstones, but in some cases the water is so strongly charged with hydrogen sulfide that it is undesirable for domestic use. In some localities water is obtained from the Rock Island (No. 1) coal or the sandstone underlying it. • PLEISTOCENE SYSTEM The principal water horizons in the Pleistocene deposits are : ( 1 ) sands and gravels deposited in Yarmouth channels, which were subsequently cov- ered by Illinoian glacial till; (2) lenticular sands and gravels in the Illinoian till; and (3) the Peorian loess. CITY WATER SUPPLIES The city of Aledo obtains water from two deep wells, No. 1 drilled about 1889, and No. 2 drilled in 1925. (Appendix C, wells Nos. 20 and 21.) Well No. 1 was originally drilled to a depth of 3114 feet to a low level in the Mt. Simon sandstone, but was filled up to a depth of 1450 feet below the surface because of the high salinity of the water from lower levels. 6 The average daily yield to February, 1924, was 148,000 gallons. During a test 200 gallons a minute was drawn. The water level in 1913 was about 100 feet below the ground surface. City well No. 2 was sunk to a depth of 1172 feet. It is situated only a short distance from well No. 1. The well was pumped at a rate of 500 gallons a minute during a test in 1926. When the pump was not in operation, the water level was 146 feet below the ground surface. The village of Alexis obtains its water from a well 1200 feet deep, drilled in 1898. The principal yield is from the St. Peter sandstone, and the bottom of the well is at or near the base of this formation. The average daily yield from April, 1922, to January, 1923, was about 21,000 gallons per day, with a production of approximately 67 gallons per minute, operating five hours a day. When the pump was not operating, the water-level was reported to be about 70 feet below the ground surface in 1915, and 120 feet below in March, 1924. 7 The village of Viola obtains water from a well 1281 feet deep, drilled in 1916. The principal yield is from the St. Peter sandstone and the bottom 6 Habermeyer, G. C, Public ground-water supplies in Illinois: Illinois State Water Survey Bull. No. 21, p. 15, 1925. 7 Habermeyer, G. C., op. cit., p. 16. 150 ALEXIS QUADRANGLE of the well is near the base of this formation. The average amount of water pumped daily in 1926 was estimated at from 10,000 to 15,000 gallons. At the time of installation the pump delivered 71 gallons a minute. When the well was first completed, the water-level was 175 feet below the ground surface, 8 and in 1926 it was said to be 22 feet lower. The village of Little York obtains water from a well drilled in 1915, to a depth of 326 feet. The water comes chiefly from a basal Devonian or Upper Silurian aquifer. The daily yield in 1922 was estimated as about 4,000 gallons. Pumping tests showed a yield of about 33 gallons per minute. In 1922 the water-level was 45 feet below the ground surface. 9 The communities of Burgess, Gilchrist, and Norwood have no public water supplies, but are supplied by several privately owned shallow wells deriving water from the glacial drift. At the old coal mining community of Wanlock a well 1230 feet deep into the St. Peter sandstone was sunk about 23 years ago and obtained a yield of water. The Hydraulic Press Brick Company at Shale City uses a well 361 feet deep, in which the water is derived from the porous horizon in the Niagaran series. FARM WELLS WELLS DERIVING WATER FROM ROCK Many farms in the vicinity of the Sunbeam School, T. 13 N., R. 3 W. (Ohio Grove Twp.), and many others between the valleys of Cedar Creek and Henderson Creek in T. 12 N., R. 3 W. (Sumner Twp.), east and north- east of Little York, obtain water from the porous zone in the upper part of the Niagaran series. The wells range in depth from 280 to 550 feet (Ap- pendix C, wells Nos. 32 and 84, and PI. VI). Most of the farm wells in the southeast quarter of the quadrangle obtain water from Pennsylvanian sandstones which immediately underlie the Pleisto- cene deposits. The depths to the sandstone are usually 65 to 100 feet. WELLS DERIVING WATER FROM THE GLACIAL DRIFT Most farm wells in the Alexis quadrangle obtain water from the Pleisto- cene deposits. The wells are either dug wells, 20 to 30 feet deep, in which surficial water collects, or are bored wells 50 feet or more in depth which penetrate sand or gravel beds in or below the Illinoian till. Sands and gravels in the form of valley-train deposits associated with either the recession of the Kansan glacier or the advance of the Illinoian glacier apparently serve as the chief source of water for the bored wells. Habermeyer, G. C, op. cit., pp. 659-661. Habermeyer, G. C, op. cit., pp. 361-362. SOILS RESOURCES 151 The wells of the farms along the county-line road between Mercer and Warren counties west ten miles from the crossing of Toms Creek, two miles west of Alexis, obtain water from sand and gravel at depths of 80 feet to 110 feet. North of Duck Creek valley the sands are absent. A group of flowing w r ells bored 50 to 60 feet deep is situated in the alluvial plain of Goose Run in sees. 16, 17, 18, 19, T. 13 N., R. 2 W. (Suez Twp.). xAithough some of these were drilled thirty or more years ago, the wells are still flowing. The boring of new wells is reported to have ap- preciably diminished the flow of older wells. In wells on the sides of the valley the water does not quite reach the surface. The wells derive their water from sands in a pre-Illinoian drainage channel sealed off by Illinoian till. SPRINGS Several farms use water obtained from springs that issue where gravel lenses in glacial drift crop out. Most of these springs have a small flow. The largest spring in the quadrangle is located at the base of the Yarmouth sands, in the SW. % SW. }i sec. 3, T. 12 N., R. 3 W. (Sumner Twp.) south of Henderson Creek and west of a wagon road. A permanent stream issues from this spring. SURFACE WATER At several places in the quadrangle surficial water sufficient for local use is collected in small reservoirs costructed by building earth dams across narrow gullies. The abundant streams throughout the area provide a supply of surficial water adequate for animals in pasture. It is reported that the Chicago, Burlington and Quincy Railroad at Little York obtains water from Cedar Creek but that the quality of the water is poor because it is polluted by sewage from Galesburg and Monmouth. 10 Soils introduction Soil is the chief source of wealth in the Alexis quadrangle, as the chief industry, agriculture, depends on it. The materials out of which the present soil has been formed are principally loess, till, slope-wash, and alluvial de- posits. The soils differ in texture, color, and calcareous and carbonaceous content according to, (1) the character of the sediment from which they have been formed, and (2) the action of the surface and subsurface drainage since the beginning of soil formation. The distribution of numerous types of soil in the quadrangle has been mapped in detail. 11 10 Habermeyer, G. C. Public ground-water supplies in Illinois: Illinois State Water Survey Bull. No. 21. p. 361, 1925. "Smith, R. S., DeTurk. K. E., Bauer. F C. and Smith. L. H.. Mercer County soils: University of Illinois Agr. Exp. Sta. Soils Report 29, 192."). See map opposite page 4. Warren County Soils: University of Illinois Agr. Exp. Sta. unpublished map. 152 ALEXIS QUADRANGLE SOILS CLASSIFIED ACCORDING TO PARENT MATERIAL SOILS OX LOESS The soils developed on the loess, which is found on uplands, on gentle slopes leading down to the larger stream valleys, and on terraces, are classi- fied 12 as brown silt loam (uplands and terraces), yellow-gray silt loam (up- lands, slopes, and terraces), black clay loam (uplands), and brown-gray silt loam on tight clay (terraces). Black clay loam is developed only on poorly drained, flat uplands and is unimportant in the Alexis quadrangle. Brown silt loam is characteristic of the level or gently rolling portion of the upland plain and also occurs in small areas on the terrace remnants along Pope Creek, Henderson Creek. Cedar Creek, and Edwards River. The yellow-gray silt loam is also a char- acteristic upland soil but occurs only near deep drainage lines. It is most abundant in the dissected uplands near the valleys of the main creeks. The more prominent terrace remnants along Pope Creek also have yellow-gray silt loam soil. The brown-gray silt loam on tight clay is reported to be de- veloped on portions of a gently sloping terrace along Edwards River north and east of Aledo. The surficial loam, 6 to 7 inches deep, varies in color from brown with a gray cast to grayish-brown. It is underlain to a depth of IS to 20 inches by a floury, friable silt loam, gray in color, with some streaks and splotches of yellow. The tight clay is a plastic, compact, mottled, grayish-drab clay containing brownish-red iron concretions and extends to a depth of about 38 inches. 18 SOILS OX GLACIAL DRIFT AXD SLOPE- WASH The chief soil on thin loess, glacial drift, and slope-wash, is yellow silt loam. This is developed on the steeper slopes over the entire quadrangle and constitutes nearly one-fifth of its total area. The loess is washed down from higher on the slope and generally forms a thin cover over the drift, which is exposed in recent gullies and slopes. The yellowish color is due to frequent wetting and drying on the slopes and to good drainage conditions. As this soil occurs chiefly on slopes, which are subject to active erosion if cultivated and deforested, it is usually left as pasture land. SOILS OX ALLCVIAL DEPOSITS The soil type most widespread on the alluvial plains of rivers is dark brown silt loam. It is developed on the valley plains along all of the larger streams and along the lower courses of the larger tributaries. It is slightly acid where not subject to flood. The upper seven inches of the soil along 12 Smith, R. S.. DeTurk. E. E.. Bauer. F. C and Smith, L. H., Mercer County Soils: Universitv of Illinois Agr. Exp. Sta. Soils Report 29, 1925. 13 Op. cit., p. 19. OIL AND GAS 153 the margins of the alluvial plain along North Henderson Creek is a plastic, black, clay loam, alkaline because the drainage is poor. SOILS CLASSIFIED ACCORDING TO CONDITIONS OF DEVELOPMENT The processes which result in the formation of a soil affect the unexposed subsoil zone as well as the surface of the soil. The principal changes are: (1) the oxidation of iron minerals and carbonaceous material; (2) the leach- ing of soluble compounds, such as calcium, carbonate; (3) the solution of various silicate minerals by waters charged with organic acids; (4) the me- chanical downward wash of finer particles or colloidal materials; (5) the precipitation in the subsoil of material dissolved nearer the surface ; and (6) the precipitation of humate salts in the soil and, to some extent, in the subsoil. On poorly drained surfaces, such as level interstream divides and swampy lowlands, the decaying vegetation accumulates so rapidly that the soil has a black or dark gray color. Better drainage conditions result in more rapid oxidation and reduction of carbonaceous material, so that the soil is light brown to buff in color. Possibilities of Oil and Gas Production introductory statement No oil or gas has ever been produced in the Alexis quadrangle, and a show of oil has been reported in only one of the four test wells drilled in the quadrangle. There appears little likelihood that oil or gas in commerial quantities will ever be produced in the quadrangle. However there are some structures that would be favorable sites for testing if other factors are favor- able, and as some formations from which oil has been produced elsewhere in the State underlie the quadrangle, the remote possibilities of such produc- tion must not be ignored. POSSIBLE OIL-BEARING FORMATIONS The lowest horizon at which oil has ever been discovered in Illinois is the "Trenton", which is represented in the Alexis quadrangle by the Platteville- Galena formations. However, no commercial production has ever been ob- tained from this horizon in northern Illinois. The next higher possible oil- bearing horizon is the Silurian system — the Hoing sand in the Colmar oil field several miles south of the Alexis quadrangle is believed to represent the base of the Silurian system. The porous zone at the top of the Niagaran series is a possible oil-bearing horizon, but analyses of water taken from several wells that exploit the horizon show that the water has a low salinity and this indicates that there is little chance of oil in the zone. Sandstone 154 ALEXIS QUADRANGLE strata or lenses in the Mississippian and Pennsylvanian systems are sources of large production in southeastern Illinois, but they have been penetrated by so many wells in the Alexis quadrangle without showing any oil that they can be considered barren. FAVORABLE STRUCTURAL AREAS The only structure affecting the middle Paleozoic rocks that appears favorable is the anticlinal nose in the southwest corner of the quadrangle (fig. 38, p. 108). Favorable structures affecting the Silurian and Devonian systems occur in the north and the southwest parts of the quadrangle (fig. 39, p. 110). Favorable structures affecting the Pennsylvanian system are not well determined, although the domes in the north part of the quadrangle (fig. 40, p. 112) are most promising. PREVIOUS OIL-TESTS One test on the farm of H. E. Robbins, NW. y A NW. *4 sec. 2, T. 13 N., R. 2 W. (Suez Twp.), was sunk to a depth of 1300 feet into the Shakopee dolomite, 20 feet below the base of the St. Peter sand- stone. The surface elevation is 733 feet. According to Mr. B. McLaughlin of Viola, two oil shows were encountered. The first was at a depth of about 800 feet in a sand 11 feet thick, which would be approximately at the top of the Galena dolomite below the Maquoketa shale. The other was at a depth of nearly 1200 feet, near the top of the St. Peter sandstone. A test on the farm of Will Laird, NW. y A SE. ]/ A sec. 14, T. 14 N., R. 3 W. (Mercer Twp.), surface elevation 753 feet, was sunk to 912 feet and finished near the middle of the Galena dolomite. No shows of oil were reported except at a depth of 95 feet at the top of the Pennsylvanian. The oily substance found here may be the product of organic decay of the surface soil material under the glacial drift, and no significance is attached to this report. A test situated in the alluvial plain of North Henderson Creek, on the farm of Elder Smith, near the southern margin of the SE. 54 SW. J /\. sec. 19, T. 13 N., R. 2 W. (Suez Twp.), surface elevation 628 feet, was sunk to a depth of 885 feet, probably ending near the base of the Galena dolomite. Samples at intervals of 5 feet from a depth of 200 feet to the bottom of the well were examined by the State Geological Survey. No shows of oil from this well were reported to the writer. A test situated on the Cook farm, near the SW. corner NW. >4 SE. J /4 sec. 31, T. 14 N., R. 2 W. (Greene Twp.), was sunk to a depth of 806 feet, probably ending near the top of the Galena dolomite. Neither details of the log nor reports regarding shows of oil were obtained for this test. OIL AND GAS 155 Other wells which have entered the St. Peter sandstone are the village well of Alexis, NE. }4 NE. }i sec. 1, T. 12 N., R. 2 W. (Spring Grove Twp.), the village well of Viola which is situated in the NE. % SE. % sec. 15, T. 14 N., R. 2 W. (Greene Twp.), two city wells of Aledo, SW. ji SE. y A sec. 17, T. 14 N., R. 3 W. (Mercer Twp.), and a water well drilled by the Alden Coal Company at Wanlock near the center of the N. line SW. ]/ A sec. 9, T. 14 N., R. 2 W. (Greene Twp.). City well No. 1, Aledo, was drilled to a depth of 3,165 feet, ending about 700 feet below the top of the Mt. Simon sandstone (Cambrian). AREAS MOST FAVORABLE FOR TESTING Each of the anticlinal areas (figs. 38, 39, and 40) is outlined on very incomplete data. Therefore two or more shallow tests should be made before deeper drilling is attempted. These shallow tests should be carried to the top of the Devonian limestone, which is the shallowest pre-Pennsyl- vanian guide horizon that will be encountered at most places in the quad- rangle. (Fig. 39.) None of the four oil-tests so far made and none of the deep water wells appear to be located favorably for testing any of the structures. Areas which at present are considered most favorable for testing are: (1) sec. 15, T. 12 N., R. 3 W. (Sumner Twp.) ; (2) sees. 19 and 20, T. 12 N., R. 2 W. (Spring Grove Twp.) ; and (3) sees. 13 and 14, T. 14 N., R. 3 W. (Mercer Twp.). Deep tests should go through the Galena dolomite in these areas. APPENDIX A Tabulated List of Fossils from Pennsylvanian Strata in the Alexis Quadrangle key to strata Suite I: I — Limestone bed. Suite II : Ha — "Stigmarian"' sandstone ; IId x — black carbonaceous shale overlying Rock Island (No. 1) coal; IId 2 — concretions in the black carbonaceous shale; Ilej — limestone cap-rock; He., — hard nodular limestone above the cap -rock; Ilfj — shaly limestone ("Blue rock"); IIf 2 — chalky limestone. Suite IV: IVfj — Gray calcareous shale above the black laminated shale; IVf 2 — septarian concretions near base of the gray shale; IVf.. — small calcareous concretions in the gray shale; IVg — brown concretionary limestone above the gray shale. KEY TO LOCALITIES 1. Sees. 32 and 33, T. 14 N., R. 2 W. (Greene Twp.). 2. Along Edwards River, sec. 29, T. 15 N., R. 1 W. (Richland Grove Twp,). 3. J. Snell mine, sec. 6, T. 14 N., R. 2 W. (Greene Twp.). 4. Dump of old mine 200 feet east of bridge over creek south of center of sec. 5, T. 14 N., R. 2 W. (Greene Twp.). 5. Dump of Neverseen Coal Co. mine, about 300 yards north of center of sec. 3, T. 14 N., R. 2 W. (Greene Twp.). 6. Dump of old mine 300 yards north of bridge over creek, west of center of south line of sec. 6, T. 14 N., R. 2 W. (Greene Twp.). 7. Dump of old mine 131 feet northeast of SW. corner sec. 5, T. 14 N., R. 2 W. (Greene Twp. ) . 8. Dump of old mine in small gully about 200 feet southwest of bridge over Donahue Run, sec. 3, T. 14 N., R. 2 W. (Greene Twp.). 9. Road-cut on south side of Henderson Creek at east line of sec. 14, T. 12 N., R. 2 W. (Spring Grove Twp.). 10. Outcrop in bank of gully northwest of bridge south of middle of sec. 5, T. 14 N., R. 2 W. (Greene Twp.). 11. Outcrop in gully near southeast corner of sec. 14, T. 12 N., R. 2 W. (Spring Grove Twp.). 12. Old drift mine entrance, % mile north of quadrangle, near NE. corner sec. 32, T. 15 N., R. 1 W. (Richand Grove Twp.). 13. Small gully south of Pope Creek, 100 yards west of east line of sec. 31, T. 14 X., R. 2 W. (Greene Twp.). 14. Old drift mine on east side of creek, 6.0 yards north of center of south line of sec. 14, T. 12 N., R. 2 W. (Spring Grove Twp.). 15. Gully in NW. % SW. % sec. 23, T. 14 N., R. 2 W. (Greene Twp.). 16. Gully near center of E. % NE. *4 sec. 30, T. 12 N., R. 1 W. (Kelly Twp.). 17. Outcrop near center of E. V 2 NW. *4 sec. 30, T. 12 N., R. 1 W. (Kelly Twp.). 18. Gully northeast of center of sec. 36, T. 15 N., R. 3 W. (Perryton Twp.). 157 158 APPENDIX A PENNSYLVANIA!* FOSSILS 1 I Strata a J d x 1 d 2 Locality 1 1 2 ! 3 4 o 3 6 7 4 Foraminifera Corals Worms x Crinoids ("sea-lilies") X Bryozoa ("leaf-corals") x X X .... X Brachiopods (lamp-shells) x .... X X x 9 x .... X x .... X X X X ; X Derbya crassa (Meek & Hayden) X x X XXX X X X X x x .... X X X X X XXX .... X • • • • X X X X X X x x .... X x .... X X x x .... x** x X x** x x** XXX x° x° X Pelecypods (clams, mussels, etc.) x ° X ° x X X x° X° X" x° x°. . . . x° x° Edmondia g-ibboaa (McCoy) .... x .... X ** Abundant. ° Characteristic. * Common. a Small wide form with a prominent central band, b Dwarfed. APPENDIX A 159 Pennsylvania:* Fossils II rv ! d 2 *t | e 2 j f, I h ! 1 s 5 8 8 9 10 1 11 12 13 14 10 11 9 12 13 14 15 1 16 17 15 18 1 15 1 15 X 1 1 1 1 1 . . . X a X a ::!:::. X X X i . • • 1 '*" i i x]...- x X .... X X ■' x x° x° •••• X X x .... x XXX ■ ' i * ' 1. ... | X 1 1 | X | x .... .... X x .... x .... X X I v x l.... 1 X X x x .... X X X X 1 x .... X X X X** x **x** X X* x x .... X x X X X 1 X X X** x x .... !. X .... X • • • • X X X 1 1 X 1 X X X X X X • • • • X° X s x X X Xb Xb x X x .... x ..-.-. X X ? X 1 X X X X X af£ x° 7 9 X X X X x** X** x x X ....x**x**x**x**x** x** x** X X 9 x ... x X* X X ... X X X x 1 x .... I x° x° .... X X X x**x**x**x** x x Xb Xb Xb x° x° x X X* x°.... X x° x° 1.... ....I X Key to strata and locality is given on page 157. 160 APPENDIX A Pennsylvania^- Fossils i Strata a d i d 2 1 Locality 1 1 2 3 4 5 3 6 7 4 Edmondia nebrascensis (Geinitz) Edmondia ovata Meek & Worthen Ecimondia reflexa Meek Edmondia sp AnthraConeilo knoxensis (McChesnev) Nucula anodontoides Meek Nucula parva McChesney x Nuculopsis ventricosa (Hall) x X Leda bellistraita Stevens Leda meekana Mark Yoldia glabra Beede & Rogers | Alula g-einitzi (Meek) | Parallelodon tenuistratus (Meek & Worthen) I . Parallelodon so | Aviculopinna illinoisensis Worthen | . x Pteria ohioensis (Hcrrick) Pseudomonotis sp • Mvalina kansasensis Shumard Mvalina swallovi McChesney Schizodus alpinus (Hall) Schizodus curtus Meek & Worthen ■ Schizodus rossicus De Verneuil x° Schizodus spellmani Herrick Schizodus sp. nov x X . • X Schizodus sp Acanthopecten carboniferus (Stevens) Aviculopecten erermanus Miller & Faber. Aviculopecten hertzeri Meek ? Aviculopecten tenuilineatus (Meek & Worthen) | Aviculopecten mazonensis Worthen ' '| Aviculopecten menardi Worthen Aviculopecten rectilaterarius (Cox) . Deltooecten scalaris (Herrick > J . . . . . Deltopecten sp | . . . . Euchondria neglecta (Geinitz) .... Strebloioteria sp 1 Entolium avicu latum (Swallow) | Placunopsis recticardinalis Meek | Allorisma costatum Meek & Worthen x X Allorisma terrninale Hall Astartella compacta Girty Astartella vera Hall Pleurophorus subcostatus Meek & Worthen Pleurophorus sp. nov | x° x° x° x° Gastropods (snails) X ■ ! 1 | X X X X Trepcspira illinoisensis (Worthen) | x° x° x° x° . . | x | • X • x° x° x° Pharkidonotus percarinatus (Conrad) X ** Abundant. ° Characteristic. * Common. a Small wide form with b Dwarfed. a prominent central band. APPENDIX A 161 Pennstlvanian Fossils II IV d 2 i l 1 1 *• 1 I ! 5 8 8 9 10 11 12 13 14 10 11 9 ! 1 1 12 13 14 15 16 17 15 18 1 15 15 1 1 1 1 1 1 x 1 1 1 X 1 X* i cf |. ... I 1 | X X 1 V* . | .. .1 9 | X ::::::::! :.:::: X i l X :::::::. :::: X* i X X X X X | x .... | V X X | .... x | .... 1 X •••• X | .... ? | .... , . . . | .... Y X X | .... x X x | '".... v x X x 1 cf .... cf j of .... X X x X aff X x x .... x 9 9 X* x x x | cf x X° X° x aff .... X .... X° X° X X .... 1 .... .... X* x .... x° x° .... aff •••• ano stone Exposed at base Abandoned drift mine near the center of the SW. % NE. % sec. 4, T. L', X.. P. .2 W. {Greene Twp.) Suite II Altitude of top of coal 647 feet Limestone, shaly ( Blue rock) Limestone, blue ( Cap-rock) Clay, carbonaceous I clod | Rock Island (Xo. 1 ) coal, including carbonaceous clay parting Underclay Thickness Feet Inches 6 1 1 1 4 7 Not exposed 10. Abandoned drift mine near the centet of sec. h, T. 15 N., R. 2 W. Preemption Twp.) Altitude of top of Coal 6 65 feet Suite II Thickness Feet Inches Limestone, shaly. fossiliferous (Blue rock) 1 8 Limestone, blue. (Cap-rock) 2 1 Shale, gray and yellowish, slightly sandy 3 Rock Island | Xo. 1 ) coal, weathered in outcrop 1 9 Underclay Only top exposed 11, At entrance to abandoned drift mine in the SE. *± XW. *i sec. 31. T. 15 X.. R. 8 W. (Preemption Twp.) Altitude of top of coal 627 feet (estimated) Suite III 8. Sandstone, gray Suite II 7. Shale, light, calcareous 6. Limestone, shaly. fossiliferous (Blue rock) 5. Limestone, massive, blue (Cap-rock) 4. Shale and sand (clod) 3. Rock Island (Xo. 1 ) coal 2. Underclay, light 1. Sandstone (exposed in creek) Thickness Feet Inches APPENDIX B PART I 167 12. Coal-test boring in the SE. corner sec. 3k, T. 15 N., R. 2 W. (Preemption Twp.) Altitude of top of coal approximately 620 feet Thickness Feet Inches 9. Loess (Pleistocene) 10 8. Sand and gravel 12 7. Clay, blue 2 3 6. Sand and gravel 6 Suite II 5 . Limestone, shaly ( Blue rock ) 12 4. Limestone, blue (Cap-rock) 1 6 3. Shale, black, laminated 1 8 2. Rock Island (No. 1) coal 4 9 1. Shale 1 13. Neverseen Coal Co. mine near SE. corner NE. V± NW. % sec. 3, T. Ik N., R. 2 W. (Greene Twp.) '■ Altitude of top of coal 054 feet Thickness Feet Inches Suite II 6. Limestone, shaly, fossiliferous (Blue rock) 12 5. Limestone, blue (Cap-rock) 1 8 4. Shale, black, laminated, fossiliferous, containing large pyritic, calcareous, fossiliferous concretions (niggerheads) 2 or less 3. Rock Island (No. 1) coal, with pyrite parting 4 6 2. Underclay, light 1 1. Sandstone Only top exposed 14. Neverseen Coal Co. abandoned drift mine,, near the center of the NW. % sec. 3, T. Ik N., R. 2 W. (Greene Twp.) Altitude of top of coal 658 feet Thickness Feet Inches Suite II 5. Limestone, shaly (Blue rock) 2 6 4. Limestone, blue ( Cap-rock) 1 3. Shale, carbonaceous (clod) 2 2. Rock Island (No. 1) coal 3 6 1. Underclay 1 15. Bonick drift mine, about 300 feet west of No. 16, sec. 3, T. l' f N., R. 2 W. (Greene Twp.) Altitude of top of coal 662 feet Thickness Feet Inches Suite II 5. Limestone, blue, rather laminated, abundant Fusulinella sp. (Cap-rock) 2 4. Clay, black, carbonaceous (clod ) 2 3. Rock Island (No. 1) coal 1 6 2. Underclay, light sandy 1 3 1. Sandstone, light (exposed) 2 16. Entrance to abandoned drift mine, near the NW. corner SE. % sec. 3, T. V, N., R. 2 W. (Greene Twp.) Altitude of top of coal 663 feet Thickness Feet Inches Suite II 6. Limestone, shaly (Blue rock) 6 9 5. Limestone, blue, fossiliferous, containing Fusulinella sp. (Cap- rock) 2 6 4. Shale, black, carbonaceous (clod ) 3 3. Rock Island (No. 1) coal 3 2. Clay, blue-gray 4 1. Underclay, white or light gray 1 168 ArPENDIX B PART I 17. Black Diamond Coal Co. mine shaft,, center of the SE. % SW. *4 sec. 2, T. ]$ N., R. 2 W. (Greene Twp.) Altitude of top of coal 646 feet Thickness Feet Inches 7. Drift and sand 17 Suite II 6. Limestone, shaly ( Blue rock) ] 4 5. Limestone, blue (Cap-rock) 2 4. Shale, black, hard, laminated (miners' "slate'') 1 6 3. Rock Island (No. 1) coal 4 3 2. Underclay 0-6 1. Sandstone Only top exposed J 8. At entrance to Kness Coal Co. mine near the center of the SW. y± NW. % sec. 11, T. Ik N., R. 2 W. (Greene Twp.) Altitude of top of coal 656 feet Thickness Feet Inches 8. Drift and sand 23 Suite III 7. Sandstone, yellowish, and shale 5 Suite II 6. Limestone, shaly (Blue rock) 2 4 5. Limestone, blue (Cap-rock) 1 8 4. Clay, carbonaceous, soft 1-2 3. Rock Island (No. 1) coal, with discontinuous level of pyrite concretions 4 2. Underclay, light , 6 1. Sandstone, with some hard, flinty layers Base of mine 19. Coal-test boring near the center of the south line of the BE. Vi NE. V± sec. 16, T. l'f N., R. 2 W. (Greene Twp.) Altitude of top of coal 670 feet 7. Clay (loess and weathered till) 6. Till 5. Sandstone Suite II 4. Limestone, shaly (Blue rock) . . . 3. Limestone, blue (Cap-rock) 2. "Slate" (shale) 1. Rock Island (No. 1) coal Thickness Feet Inches 26 60 9 7 1 6 11 5 2 4 10 20. CoaZ test boring near the center of the west line of the NE. % NE. "M sec. 20, T. Ik N., R. 2 W. (Greene Twp.) Altitude of top of coal 637 feet 11. Soil 10. Clay 9. Clay and sand 8. Clay, blue ("sea mud").... Suite III 7. Shale ( "soapstone" ) 6. Sandstone 5. Shale Suite II 4. Slate 3. Limestone, shaly (Blue rock) 2. "Slate" (shale) 1. Rock Island (No. 1"> coal.... Thickness Feet Inches 3 21 8 10 7 57 5 2 10 8 7 8 10 2 3 5 3 8 APPENDIX B PART I 169 21. W. B. Williams mine shaft, near the NE. corner of the NW. V± NW. V* sec. 82, T. U N., R. 2 W. (Greene Twp.) Altitude of top of coal 659 feet Thickness Feet Inches 8. Loess and till (Pleistocene) 50 Suite III 7. Sandstone, chert, and shale (Suite II) 8 Suite II 6. Limestone, shaly (Blue rock) 4 5. Limestone, blue, massive ( Cap-rock) 2 0-3 4. Shale, black, laminated, containing marine fossils 1 0-8 3. Rock Island (No. 1 ) coal 4 2. Underclay, thin or absent 0-5 1. Sandstone, "Stigmarian" Exposed at base 22. Composite of sections in vicinity of G. H. Smith mine, near the center of the SW. % sec. 32, T. U N., R. 2 W. (Greene Twp.) Altitude of top of coal 665 feet Thickness Feet Inches 17. Loess and till (Pleistocene) ,, .... 40± 16. Sandstone 0-2 15. Chert 5-12 Suite II 14. Shale . 1^-2 13. Limestone, shaly (Blue rock) 8-16 12. Limestone, massive, blue (Cap-rock) 1-1% 11. Shale, black, laminated 4-10 10. Rock Island (No. 1) coal , 3^-5 9. Underclay 6-0 8. Sandstone, "Stigmarian", or sandy clay-shale 8 or less Suite I 7. Underclay, light, soft 4 6. Covered, probably shale or underclay 6 5. Limestone, blue, hard, evenly bedded, sparingly fossiliferous. . 8 4. Coal 2 6 3. Underclay, gray, sandy, lower part blue-gray 5 6 2. Underclay, gray, sandy 4 1. Shale, blue, containing ironstone concretions 4 6 23. Cut bank on north side of Henderson Creek about 250 yards northwest of the center of the east line of sec. U, T. 12 N., R. 2 W. (Spring Grove Twp.) Altitude of top of coal 657 feet Thickness Feet Inches 8. Loess and till Not measured 7. Sandstone, thinly bedded, soft 2 6. Sandstone, thin, brownish, soft, blocky, containing abundant poorly preserved traces of charcoalized wood and numerous remains of the hard parts of fish (Petrodus occidentalis, etc. ) 6 Suite II 5. Limestone, shaly, and shale, calcareous (Blue rock) 5 4. Limestone, blue, massive (Cap-rock) 3 6 3. Rock Island (No. 1) coal (exposure covered by slump). Re- ported 3 2. Underclay 3-4 1. Sandstone, thinly bedded, light colored, containing traces of Calamites and Stigmaria 12 170 APPENDIX B — PART I 24. At entrance to abandoned drift mine near the SE. corner SW. % sec. li h T. 12 N., R. 2 W. (Sirring Grove Twp.) Altitude of top of coal 652 feet Thickness Feet Inches 8. Loess and till (Pleistocene) Not measured 7. Chert 1 Suite II 6. Shale . 5. Limestone, chalky, fossiliferous ; weathers yellowish 4. Limestone, shaly, fossiliferous (Blue rock) 3. Limestone, hard, nodular, slightly fossiliferous 2. Limestone, blue, hard, evenly bedded (Cap-rock) 1. Rock Island (No. 1) coal (exposed) 25. Exposures in gully about 200 yards west of the east line of sec. l! h T. 12 N., R. 2 W. (Spring Grove Twpja Altitude of top of coal 651 feet 14. 13. 12. 11. 10. 9. Loess and till (Pleistocene) Sandstone, thinly bedded, black to yellowish, shaly.... Clay, most covered Shale, black, carbonaceous (horizon of thin coal bed) Sandstone, hard, containing Stigraaria Sandstone, thinly bedded, soft Chert, in two benches Thic Feet 5;: 7 6 ivness Inches Suite II thin Shale, light gray, hard, silicified Shale, calcareous, dark gray, rather hard Limestone, shaly, blue-gray, slabby, splitting in broad plates, fossiliferous (Blue rock) Limestone, hard, nodular, with wavy lines of bedding ; blue- gray where fresh, weathering buff; sparingly fossiliferous.. Limestone, slabby, blue-gray where fresh, weathering dark gray; containing Fusulinella sp. (Cap-rock) Shale, laminated, black, hard Rock Island ( No. 1 ) coal a This exposure is similar to the section in Bailey mine shaft at head of this gully in sec. 23, same township. 26. Richardson mine shaft near the center of the SW. x /i NW. Vi sec. 2' h T. 12 N., R. 2 W. (Spring Grove Twp.) Altitude of top of coal 647 feet Alluvium and till (Recent and Pleistocene) Coal Underclay and sandstone Thickness Feet Inches 13 Suite II Limestone (Blue rock and Cap- rock) Shale, black, laminated Rock Island ( No. 1 ) coal Shale, pyritic, coaly (false bottom) . Underclay , Sandstone 3-4 1 4 Exposed APPENDIX B PART II 171 27. McCartney mine shaft (abandoned) near the center of the east line of the SE. '/4 NW. % sec. 2k, T. 12 N., R. 2 W. (Spring Grove Twp.) Altitude oi top of coal 635 feet Thickness Feet Inches 5. Loess and till (Pleistocene) 23± Suite II 4. Limestone (Blue rock and Cap-rock) 15 3. Shale, black, laminated 2 2. Rock Island ( No. 1 ) coal 4 I. Sandstone Exposed at base Part II. — Measured geologic sections of Suite IV, Colchester (No. 2) coal and associated strata The following sections are graphically represented in figure 24, p. 81. 1. Outcrop near the middle of the west line of the NW. % SW. % sec. 23, T. Ik N., R. 2 W. (Greene Twp.) Altitude of top of coal 735 feet Thickness Feet Inches 12. Loess and till (Pleistocene) Not measured Suite IV II. Shale, gray, soft 1 10. Limestone, brown, concretionary, very fossiliferous 5 9. Shale, gray, soft, with flattened septarian calcareous concre- tions at two or three levels. Concretions fossiliferous (Ap- pendix A 4 6 5. Limestone, concretionary, gray, septarian, fossiliferous, in gray shale which is also fossiliferous at this level (Appen- dix A) 6 7. Shale, gray, soft -. 1 6. Shale, black, laminated, nodular, with very small plant frag- ments preserved in small calcareous concretions. Few large calcareous and pyritic concretions or "niggerheads"' irregu- larly distributed 1 5. Colchester (No. 2) coal, rather hard, even, strongly pyritic, sulfur stains prominent in outcrop face 1 4. Underclay, strongly sulfurous, containing silicified roots 5 3. Underclay, sandy, containing hard spherical concretions of septarian structure 1 2. Sandstone, light, thinly bedded 8 Suite III 1 . Shale, gray, soft — 2. Composite section of exposures in gully near the middle of the east line of the SE. *A NE. % sec. 21. T. Ik N. } R. 2 W. (Greene Twp.) Altitude of top of coal 729 feet Thickness Feet Inches 11. Loess and till (Pleistocene) Not measured Suite IV 10. Limestone, septarian concretions, forming nearly solid ledge.. S 9. Shale, dark gray, soft 2 8. Shale, black, hard, laminated, containing small calcareous concretions which give pitted or pimply appearance to bed- ding surface 2 7. Colchester (No. 2) coal 2 + 6. LTnderclay, white, containing a few silicified roots extending down from coal bed 5 4- 172 APPEXDIX B — PART II Suite III 5. Shale, sandy, and sandstone, thinly bedded 4. Gilchrist shale, gray, with calcareous concretions at various levels 3. Shale, reddish 2. Shale, gray, with large flattened ovoid concretions at some levels 1. Sandstone, massive Thickness Feet Inches 18 1 11+ Xos. 1 to 4 of the above section are exposed further down this gully chan location given, in sec. 2 6, T. 14 X., R. 2 W. (Greene Twp.). 3. Exposures in gully near the middle of the east line of the XE. *i SW. 1 i sec. 1, T. 13 X., E. 2 TV. (Suez Twp.) Altitude of top of coal 713 feet Thickness Feet Inches Loess and till (Pleistocene) Not measured Suite IV Shale, black, hard, laminated, containing small concretions giving pimply surface Shale, black, carbonaceous, soft Colchester (Xo. 2) coal, containing irregular 1- to 2-inch part- ings of pyrite about 4 inches from base 1 nderclay, light Sandstone, rather soft, weathers yellow, containing many large, irregular, egg-shaped concretions 1 foot in diameter Sandstone, containing hard, blue-gray, calcareous concretions having maximum diameter of s to 10 feet. Bedding of sandstone appears to bend around concretions 10- 4. Entrance to abandoned drift mine near the middle of the south line of the SW. % XW. *i sec. 20, T. 12 X., E. 2 W. (Spring Grove Tv;p.) Altitude of top of coal 661 feet 3. Loess, slump, and till . Thickness Feet Inches Xot measured Suite TV 2 . Shale, soft, gray 5 1. Colchester (No. 2~) coal, weathered and poorly exposed; re- ported 2 4 5. Exposure in small gully near the center of the SE. ] /$ SW. \\ sec. 19, T. 12 X., E. 1 W. (Kelly Ticp.) Altitude of top of coal 69S feet Thickness Feet Inches 6. Loess and till (Pleistocene) Xot measured Suite IV 5. Clay, soft 2 4. Shale, hard, black, laminated, upper part rather pimply, con- taining small concretions 1 3. Shale, soft, gray 9 2. Colchester (Xo. 2) coal, poorly exposed Suite III 1. Shale, soft. gray, grading down into thinly bedded micaceous shale S 10 + APPENDIX B — PART III 173 6. Exposure in gully near the center of the E. V 2 NE. % sec. 30, T. 12 N., R. 1 W. (Kelly Twp.) Altitude of top of coal 691 feet • . Thickness Feet 8. Loess and* till (Pleistocene) Not measured Suite IV 7. Shale, blue-gray, calcareous, containing large septarian limestone concretions, f ossilif erous 2 6. Shale, gray, without septarian concretions 8 5. Concretions, massive, septarian, with concentric and radial structure of calcite veins 2 4. Shale, black, laminated, with pimply surface 2 3. Colchester (No. 2) coal, poorly exposed 2± 2. Clay, light 3 Suite III 1. Shale, greenish-gray, containing some plant fossils 8-10 7. Exposure in gully near the SW. corner of the SE. V± NW. % sec. SO, T. 12 N., R. 1 W. (Kelly Twp.) Altitude of top of coal 720 feet Thickness Feet Inches 6. Loess and till (Pleistocene) Not measured Suite IV 5. Shale, gray, containing large septarian limestone concretions, fossiliferous 3 4. Shale, black, hard, laminated, with pimply surface due to numerous small concretions 1 6 3. Colchester (No. 2) coal, even, rather hard, a little pyrite 2 2. Underclay, light gray, rather sandy 3 + Suite III 1. Shale, blue-gray, evenly bedded 10 Part III. — Mine data Kness Coal Company Location: Center of SW. % NW. % sec. 11, T. 14 N., R. 2 W. (Greene Twp.). En- trance: Shaft 32 feet deep. Altitude of top of coal: 667 feet. Roof: Massive blue lime- stone ("Cap-rock''); excellent. Coal: 42-48 inches thick; local pyrite concretions 2-18 inches below top of coal. Floor : Sandy clay, 6 inches thick, overlying massive sandstone, 5 feet or more thick. Black Diamond Coal Company Location: Center of SE. % SW. % sec. 2, T. 14 N., R. 2 W. (Greene Twp.). En- trance : Shaft 35 feet deep. Altitude of top of coal : 645 feet. Roof : Black laminated shale 18 inches thick, underlying limestone ("Cap-rock") ; shale forms excellent roof, but checks where exposed to air for several years ; some "roof falls." Coal : 48-54 inches thick; thin pyrite concretions in some places, 18 inches below top of coal. Floor: Sandy clay, 1 foot thick, overlying sandstone. Neverseen Coal Company Location: Near SE. corner NE. 14 NW. % sec. 3, T. 14 N., R. 2 W. (Greene Twp.). Entrance: Slope 6 feet down. Altitude of top of coal: 660 feet. Roof: Black laminated shale, 2 feet or less thick, in depressions; limestone roof on "rolls'' ; shale forms good roof except where thinner than 8 inches, where it weathers to "clod" and may fall ; some con- cretions ("niggerheads") in shale. Coal: 48-54 inches thick; locally contains pyrite concretions as much as 5 inches thick, 30 inches below top of coal. Floor : Sandy clay, thin, or sandstone where clay is absent. Special features : Small faults with clay seams are present in coal ; water enters through these faults or through sandstone floor. 174 APPENDIX B PART III Bonick Mine Location: Near center of sec. 3, T. 14 N., R. 2 W. (Greene Twp.). Entrance: Drift not completed when visited. Altitude of top of coal: 662 feet. Roof: Clay or "clod,'' 2 inches thick, underlying- blue limestone ("Cap-rock"). Coal: 18 inches thick at drift entrance. Floor : Light, sandy clay and sandstone ; 2 feet 6 inches were removed with coal when driving drift Peterson Mine (Formerly Pleasant Valley Coal Company Mine) Location: Near center of NW. % SE. % sec. 4, T. 14 N., R. 2 W. (Greene Twp.). Entrance: Slope about 15 feet down to coal. Altitude of top of coal: 655 feet. Roof: Clay, 2 to 3 inches thick, underlying massive blue limestone ("Cap-rock") ; clay removed with coal. Coal : 40-54 inches thick, including bedded carbonaceous clay band 10-24 inches thick, 18 inches below top of coal. Floor: "False bottom,'' 6 inches thick, overlying sandstone. Special features : Wide solution cracks common in limestone ; large amount ■of bedded impurities is a handicap in mining. Mack Mine Location: Near NE. corner SW. % NE. % sec. 4, T. 14 N., R. 2 W. (Greene Twp.). Entrance : Slope drift ; mine not in operation when visited, but an old drift near entrance showed conditions similar to those in Peterson mine. Lee Mine Location: 150 yards west of Peterson mine, NW. % SE. % sec. 4, T. 14 N, R. 2 W. (Greene Twp.) ; this mine, newly opened in 1925, was not in operation when visited; Conditions reported are similar to those in Peterson mine. Hydraulic Press Brick Company Mine (Abandoned February, 1926) Location : Near NE. corner of SW. % SW. % sec. 5, T. 14 N., R. 2 W. (Greene Twp.) ; a mine of same company half a mile south was abandoned about January, 1923. Entrance: Slope about 12 feet down to coal. Altitude of top of coal: 638 feet. Roof: Black laminated shale up to 3 feet thick, underlying limestone ("Cap-rock") ; good roof except for some caving where shale is thin. Coal : Average thickness, 60 inches, including 12 inches bedded clay 20 inches below top of coal; thin pyritic concretions in a band 16 inches below top of coal. Floor : "False bottom" a few inches thick, overhang sandstone. Special features : This mine was close to Alden Coal Company No. 1 (Old Gilchrist) mine which was abandoned 30 years ago, several times it was flooded by tapping water- filled rooms of the old mine ; one of these floods caused abandonment of mine. Core-drilling tests in 1923 showed coal thinned to 6 inches a quarter of a mile south of the working face. J. Snell and Sons Coal Mine Location : Near middle of north line of SW. % SW. % sec. 6, T. 14 N., R. 2 W. (Greene Twp.). Entrance: Slope 14 feet down to coal. Altitude of top of coal: 663 feet. Roof: Black laminated shale, 1 foot or less thick, underlying limestone ("Cap-rock"); many large concretions ("niggerheads") in shale cause poor roof in some parts of mine; limestone forms roof in some places. Coal: 46-50 inches thick including 12 inches of bedded black carbonaceous clay 20 inches below top of coal. Floor : 2 feet of gray clay overlying hard sandstone. Special features : The large concretions in the roof shale were more numerous in this mine than in any other visited. McNeill Mine (Abandoned in 1926) Location: Near NW. corner of SW. % sec. 33, T. 15 N., R. 2 W. (Preemption Twp.). Entrance: Slope about 6 feet above coal. Altitude of top of coal: 643 feet. Roof: 2-3 inches soft clay underlying blue limestone ("Cap-rock"). Coal: 27 inches thick, no shale or pyrite parting. Floor: Clay 12 inches thick overlying sandstone. Special features: Cracks 8 inches wide in limestone admit much water. APPENDIX B PART III 175 Williams Mine (Formerly George Martin mine) Location: Near NE. corner of NW. % NW. % sec. 32, T. 14 N., R. 2 W. (Greene Twp.). Entrance: Shaft 70 feet. Altitude of top of coal: 639 feet. Roof: Black shale 20 inches thick in depressions, thins out on "rolls" under limestone ("Cap-rock") ; fine- grained, nodular, shaly limestone ("Blue-rock") overlies coal in a prominent "roll"; roof is best where shale is thick ; shale shows some tendency to check after a few years exposure to air. Coal : 38-50 inches thick ; locally contains thin pyrite concretion band 17 inches below top of coal; no clay or shale bands. Floor: Sandy clay, a few inches thick, overlying hard sandstone. G. H. Smith Mine (Formerly J. B. Martin mine) Location: Near NE. corner of SW. % SW. % sec. 32, T. 14 N., R. 2 W. (Greene Twp.). Entrance : Shaft 38 feet deep. Altitude of top of coal : 665 feet. Roof : 1-2 inche& clay ("clod'') underlying massive limestone ("Cap-rock") ; excellent roof, still sound in entrances and rooms 60 years old. Coal: 42-48 inches thick; thin concretionary band of pyrite near middle of coal in some places ; no shale or clay impurities. Floor : Sandstone. Richardson Mine (Formerly Gilmore and Houston mine) Location: Near center of SW. % NW. *4 sec. 24, T. 12 N., R. 2 W. (Spring Grove Twp.). Entrance: Shaft 30 feet deep. Altitude of top of coal: 647 feet. Roof: Black laminated shale, 20 inches thick, underlying limestone ("Cap-rock"); good roof. Coal: 43-52 inches thick ; one-half inch pyrite concretions in places, 12 inches below top of coal. Floor: Carbonaceous, pyritic shale ("false bottom") 2 inches thick above gray sandy clay, overlying hard sandstone. Bailey Mine Location: Near NE. corner sec. 23, T. 12 N., R. 2 W. (Spring Grove Twp.). En- trance: Shaft 33 feet deep. Altitude of top of coal: 650 feet. Roof: Black laminated shale, 20 inches thick, underlying limestone ("Cap-rock''). Coal: Reported 48 inches thick. Floor : Probably like floor of Richardson mine. Special features : Shaft was being repaired when visited ; shaft is a third of a mile north of coal to be mined, as large masses of fine silt caved in shaft nearer coal. McCartney Mine (Abandoned March, 1926) Location: Near middle of east line of SE. % NW. % sec. 24, T. 12 N., R. 2 W. (Spring Grove Twp.). Entrance: Shaft 40 feet deep. Altitude of top of coal: 635 feet. Roof: Black laminated shale, 2 feet thick, underlying limestone ("Cap-rock"). Coal: Reported to average 48 inches thick ; no bedded impurities. Floor : Probably same as in Richardson mine. The following mines were formerly large shipping mines which have been abandoned for a number of years. Alden Coal Company Mine No. 1 (Old Gilchrist mine) Location: Near NE. corner SW. % SW. % sec. 4, T. 14 N., R. 2 W. (Greene Twp.). Entrance: Shaft about 70 feet deep. Altitude of top of coal: Approximately 650 feet. Coal : 4 feet or more thick. Special features : Coal was mined from parts of sees. 4, 5, 8, and 9, T. 14 N., R. 2 W. (Greene Twp.) (fig. 47) ; the workings extended about a third of a mile east and one and an eighth miles west from the shaft ; the Peterson and the Hydraulic Press Brick Company mines adjoin these old workings. Alden Coal Company Mine No. 2 (Wanlock mine) Location: Near NE. corner NW. % SW. % sec. 9, T. 14 N., R. 2 W. (Greene Twp.). Entrance: Shaft 132 feet deep. Altitude of top of coal: Approximately 650 feet. Roof: 176 APPENDIX B PART III Boring- near shaft shows rock, probably limestone, 3 feet 8 inches thick, over coal. Coal : 4 feet 8 inches reported in boring. Floor : No data. Special features : This mine extended north to a "fault," reported to cut out the coal between Wanlock and Old Gilchrist mines ; this reported fault may be a channel cutting out the coal, for channel sandstones are exposed about 1 mile west of here. Coal was removed from part of the SW. % sec. 9, and part of sec. 16, also from small areas in sees. S and 17, T. 14 N., R. 2 W. (Greene Twp.). (Fig. 47.) Alden Coal Company Mine No. 3 (New Gilchrist mine) Location : Near middle of west line of NE. % NE. % sec. 20, T. 14 N., R. 2 W. (Greene Twp.). Entrance: Shaft 134 feet deep. Altitude of top of coal: 640 feet. Roof: Gray shale, to 3 feet thick, underlying limestone ("Cap-rock''), 6-18 inches thick, underlying shaly limestone, 6-12 feet thick. Coal: 48-78 inches thick. Floor: Shale 2 feet thick, overlying sandstone. Special features : This mine extended about half a mile north and one mile south of shaft ; the coal was mined from a narrow strip about a quarter of a mile wide and lying chiefly in the eastern part of sec. 20, and the SE. % sec. 17 ; test drillings in the SE. % SE. % sec. 20 revealed a preglacial channel 80-90 feet deep which cuts out the coal. Alden Coal Company Mine No. 4 Location: SE. % NE. % sec. 16, T. 14 N., R. 2 W. (Greene Twp.). Entrance: Shaft, approximately 100 feet deep. Altitude of top of coal : Approximately 650 feet. Roof : Laminated shale or limestone ("Cap-rock"). Coal: 4 feet to 4 feet 10 inches thick. Special features : The coal mined from this shaft lay chiefly in sec. 16, and was connected with working of Alden mines 2 and 3 (fig. 47). Coal Valley Mining Company Mine No. 3 Location: SW. % SW. % sec. 35, T. 15 N., R. 1 W. (Preemption Twp.). Entrance: Shaft, depth unknown. Coal : Average approximately 4 feet thick ; mine map shows entries ended with coal 3 feet 3 inches to 4 feet thick. Special features : Coal has been removed from SW. % SW. % sec. 35, SE. % SE. % sec. 34, T. 15 N., R. 2 W. (Pre- emption Twp.) and NE. % NE. % sec. 3, T. 14 N„ R. 2 W. (Greene Twp.) ; coal was shipped by a spur of the Rock Island Southern Railway. APPENDIX C WELL LOGS Deep Wells, Detailed Records (Logs of wells 1-31 are shown graphically on Plate V) 1. State Asylum well; Watertown, Rock, Island County, Illinois, 1 S. y 2 NW. % SW. l k sec. 20, T. IS N., R. 1 E. (Hampton Twp.) Altitude approximately 575 feet, estimated from Cordova quadrangle topographic map Thickness Depth Feet Feet Recent and Pleistocene systems Sand, fine 85 85 Pennsylvanian system Pottsville ( ?) formation Limestone, shaly, and "slate" (shale), black 50 135 Devonian system Cedar Valley and Wapsipinicon formations Limestone, gray 115 250 Silurian system Niagaran seriesa Limestone, white (dolomite?) 300 550 Ordovician system Maquoketa formation Shale, blue 168 718 Mohawkian series Galena formation Limestone, dark gray 107 825 Limestone, light gray 100 925 Limestone, white, very hard 15 940 Platteville formation Limestone, dark gray . 100 1040 Glenwood formation Shale, gray 10 1050 St. Peter formation Sandstone, containing a few layers of limestone 1 foot thick 90 1140 Limestone 10 1150 Sandstone 10 1160 Prairie du Chien series S'nakopee formation Limestone 60 1220 Sandstone 20 1240 Limestone 20 1260 Sandstone 5 1265 Limestone, sandy 126 1391 1 Record submitted by power plant engineer. a In this and the rest of the well records, the rocks assigned to the Niagaran scries may include also the Alexandrian series, which cannot be differentiated. 177 178 APPENDIX C Deep Wells, Detailed Records — Continued 2. City well; Silvis, Rock Island County , Illinois/ N. center of the SE. y± NW. % sec. 32. T. IS N., R. 1 E. (Hampton Tivp.J Altitude approximately 580 feet, estimated from Cordova quadrangle topographic map Thickness Depth Feet Feet Recent and Pleistocene systems Sand and clay 36 36 Pennsylvanian, Devonian, Silurian, and Ordovician systems, undiffer- entiated Limestone with "veins" of bluish shale, (no trace of coal) . . 714 750 Includes Pottsville? (Pennsylvanian), Cedar Valley (Devon- ian), and Wapsipinicon (Devonian) formations, Niagaran (Silurian) and Maquoketa (Ordovician) formation, and part of Galena formation Ordovician system Mohawkian series Galena formation Large crevice followed by layer of sand 50 800 Galena, Platteville, Glenwood, and St. Peter formations and Prairie du Chien series, undifferentiated Limestone with a few "veins" (beds) of sandstone... 650 1450 Prairie du Chien series Gravel, fine 3 1453 Rock (probably dolomite) 72 1525 Cambrian system Jordan ( V) formation Gravel, fine 10 1535 Trempealeau formation Rock, hard (probably dolomite) 55 1590 Trempealeau and Mazomanie-Franconia formations, undifferen- tiated Limestone, very hard, with a few veins of sandstone 320 1910 Franconia formation Limestone, soft 15 1925 Dresbach (?) formation Sandstone, soft ....!... 55 1980 Limestone, very hard 5% 198514 2 Record submitted by Mr. F. W. Crawford. 3. Continental Ice Company well, Silvis. Rock Island County, Illinois/ sec. 32 (?), T. IS N., R. 1 E. (Hampton Twp.) Altitude approximately 575 feet, estimated from Cordova quadrangle topographic map Recent and Pleistocene systems No record 32 32 Pennsylvanian and Devonian systems Shale 118 150 Silurian system Niagaran series Limestone 285 435 Ordovician system Maquoketa formation Shale 235 670 B Driller's record. APPENDIX C 179 Deep Wells, Detailed Records — Continued Thickness Depth Feet Feet Mohawkian series Galena and Platteville formations Limestone 310 980 St. Peter formation Sandstone 40 1020 Prairie du Chien series Shakopee ( ?) formation Shale 130 1150 Ordovician (Prairie du Chien series) and Cambrian systems, undifferentiated Includes probably New Richmond and Oneota formations of the Prairie du Chien series and Jordan and Trempealeau formations of the Cambrian system Limestone and sandstone, alternating 520 1670 4. City toell No. 1, East Moline, Rock Island County, Illinois/ sec. 25 (?). T. 18 N., R. 1 W. (Moline Twp.J Altitude ^7 9 feet Recent and Pleistocene systems Drift 28 28 Devonian and Silurian systems, undifferentiated Cedar Valley and Wapsipinicon (Devonian) formations and Niagaran (Silurian) series Limestone and dolomite, white, with green shale and red marl 402 430 Ordovician system Maquoketa formation Shale, light to dark, bituminous, pyritic 265 695 Mohawkian series Galena formation Limestone and dolomite, sandy, gray to white, subgranuJar 205 900 Platteville formation Limestone, dark gray and buff, pyritic, flaky 95 995 Glenwood formation Shale, greenish, pyritic 30 1025 St. Peter formation Sandstone 50 1075 Prairie du Chien series Shakopee formation Limestone 105 1180 Marl, red .", 35 1215 Limestone 60 1275 Sandstone 3 1278 Limestone 64 1342 New Richmond ( ?) formation Limestone, sandy 23 1365 Oneota (?) formation Limestone, with streaks of sandstone 135 1500 Cambrian system Jordan and Trempealeau ( ?) formations Sandstone and limestone 32 1532 4 Compiled from drillers' logs and samples studied by J. A. Udden. 180 APPENDIX C Deep Wells, Detailed Records — Continued 5. City well No. 2, East Moline, Rock Island County, Illinois/ sec. i (Moline Twp.j Altitude 573 feet (?) } T. IS N., R. 1 W. Thickness Depth Feet Feet Recent and Pleistocene systems Gravel, sand, clay Devonian and Silurian systems, undifferentiated Cedar Valley and ^Yapsipinieon (Devonian) formations and Niagaran (Silurian) series Limestone Ordovician system Maquoketa formation Shale Limestone Shale Shale, brown Mohawkian series Galena formation Limestone Limestone, sandy Decorah formation Shale Platteville formation Limestone Limestone, sandy Limestone, brown Glenwood formation Sandstone Shale Limestone St. Peter formation Sandstone Shale Limestone, sandy Prairie du Chien series Shakopee formation Limestone New Richmond and Oneota formations Limestone and sandstone in streaks Sandstone, heavily pyritic Limestone Sandstone and limestone in streaks Cambrian system Jordan formation Sandstone, soft "Quartz rock" (hard sandstone) Sandstone "flinty'' (hard) Sandstone, soft Sandstone, sharp Trempealeau formation Limestone Shale Shale, sandy Limestone Limestone and sandstone in streaks Marl, red Mazomanie-Franconia ( ?) formation Shale, sandy Limestone 22 413 46 211 22 435 90 525 45 570 25 595 53 648 820 871 29 900 60 960 27 987 22 1009 16 1025 10 1035 55 1090 32 1122 38 1160 1371 59 1430 20 1450 10 1460 25 1485 20 1505 5 1510 20 1530 10 1540 4S 1588 12 1600 8 1608 8 1616 24 1640 135 1775 1 1776 64 1840 10 1850 5 Driller's record. APPENDIX C 181 Deep Wells, Detailed Records — Continued 6. Paper Mill Company well, Moline, Rock Island County, Illinois/ NE. corner NW. X A SW. % sec. 32, T. 18 N., R. 1 W. (Moline TwpJ Altitude 564 feet Thickness Depth Recent and Pleistocene systems Feet Feet Surface soil 7 7 Devonian system Cedar Valley and "Wapsipinicon formations Limestone 113 120 Silurian system Niagaran series Limestone 275 395 Ordovician system Maquoketa formation Shale 220 615 Mohawkian series Galena and Platteville formations Limestone 320 935 Glenwood formation Shale, sandy, and streaks of sandstone 141 1076 St. Peter formation Sandstone 65 1141 Prairie du Chien series Limestone and marl, red 316 1457 Cambrian ss'Stem Jordan formation Sandstone 121 1578 Trempealeau formation Limestone 50 1628 6 Driller's record. 7. Mitchell and Lynde well, Rock Island, Rock Island County, Illinois, 1 between East and West Seventeenth Streets, north of Second Avenue; NE. corner of the SE. % NW. % sec. 35, T. 18 N., R. 2 W. Altitude 558 feet Devonian system Cedar Valley and Wapsipinicon formations Limestone 60 60 Silurian system Niagaran series Limestone 276 336 Ordovician system Maquoketa formation Shale 180 516 Mohawkian series Galena formation (includes some Maquoketa) Limestone 353 869 Platteville formation Limestone 90 959 St. Peter formation Sandstone 145 1101 Ordovician and Cambrian systems, undifferentiated ; Prairie du Chien (Ordovician) series and Jordan, Trempealeau and Mazomania-Fran- conia (?)• (Cambrian) formations Limestone 811 1915 Cambrian system Mazomanie-Franconia formation Sandstone, dense 30 1945 Limestone 35 1980 7 Record published in U. S. Geological Survey Seventeenth Ann. Repl., pt. 2, p. 845, 1896. 182 APPENDIX C Deep Wells, Detailed Records — Continued Dresbach formation Sandstone Eau Claire formation Limestone, shaly, and shale. Sandstone Thickness Depth Feet Feet 130 2110 2185 2282 8. Modern Woodmen's well* Rock Island. Rock Island County. Illinois, near Seventeenth Street and Third Avenue; SW. % NE. V± sec. So, T. 18 N., R. 2 W. Altitude about 565 feet Devonian and Silurian systems, undifferentiated Cedar Valley and Wapsipinicon (Devonian) formations and Niagaran (Silurian) series No record Silurian system Niagaran series Dolomite, white, gray, and cream-colored, coarsely crystalline, porous, with some fragments of sandstone and lumps of green clay locally, cherty at base Ordovician system Maquoketa formation Shale, calcareous, light gray Shale, light graj% with fragments of pyritifercus dolomitic limestone Limestone, shaly, dolomitic, gray, with some flaky shale.... Shale, slightly calcareous, greenish-gray Limestone, dolomitic, dark gray, fine-grained Shale, dark gray, bituminous Shale, dark, nearly black when wet Mohawkian series Galena formation Dolomite, yellowish-gray, cherty in lower part Platteville formation Limestone, gray Glenwood formation Sandstone composed of small rounded, clear quartz grains.. Shale, greenish-gray Sandstone composed of coarse rounded grains, with fragments of stiff green shale St. Peter formation Sandstone, clean quartz grains Sandstone, cream-colored, fine in texture Sandstone, yellowish, fine in texture Shale, green (probably base of St. Peter) 160 245 35 25 8 Record compiled from samples of well cuttings examined by J. A. Udden. 9. Atlantic Brewery Company well, Rock Island, Rock Island County, Illinois, corner NW. % SE. % sec. 36, T. IS N., R. 2 W. Altitude 577 feet 160 405 440 85 525 25 550 17 567 15 582 18 600 20 620 245 865 85 950 15 965 15 980 1005 50 1055 15 1070 40 1110 13 1123 NE. Pennsylvanian ( ?) system Sandstone (?) Silurian system Niagaran series No record Dolomite, grayish- white 9 Record derived mostly from samples studied by J. A. Udden. 150 150 200 210 APPENDIX C 183 Deep Wells, Detailed Records — Continued Thickness Depth Feet Feet Dolomite, grayish-white, cherty, and sandstone, white 20 230 Sandstone, white, and clay, green 30 260 Dolomite white, and sandstone 20 280 Sandstone, white 10 290 Dolomite, white, and sandstone 90 380 Sandstone 10 390 Chert, dolomite, and sandstone 10 400 Ordovician system Maquoketa formation Shale, silty, slightly calcareous, greenish, fossiliferous 80 480 Shale, sandy, gray, pyritic 20 500 Shale, gray, with fossiliferous limestone 30 530 Shale, calcareous, gray, with darker lumps 70 600 Shale, calcareous, dark, bituminous 20 620 Mohawkian series Galena formation Dolomite, grayish-white, cherty 30 650 Dolomite, yellowish-gray, with green clay and chert locally 140 790 No record 310± 1100± 10. Rock Island Brewing Company™ Rock Island, Rock Island County, Illinois, Elm Street near Ninth Avenue; NE. corner of the 8E. % SE. % sec. 36, T. 18 N., R. 2 W. Altitude 654 feet Recent, Pleistocene, and Pennsylvanian systems, undifferentiated No record 100 100 Devonian system Cedar Valley and Wapsipinicon formations Limestone, gray, with some shale in lower 20 feet 50 150 Silurian system Niagaran series Dolomite, yellowish-brown, with cavities filled with sandy shale 375 525 Ordovician system Maquoketa formation Shale, bluish-gray 205 730 Maquoketa formation Galena and Platteville formations Limestone 330 1060 Glenwood formation Shale, blue 25 1085 St. Peter formation Sandstone, with some shale below 204 1289 Shale 61 1350 Marl, red 25 1375 Prairie du Chien series Limestone 229 1604 Cambrian system Jordan and Trempealeau formations No record 346 1950 Mazomanie-Franconia and Dresbach formations Sandstone of various colors 207 2157 "Record published in Illinois State Geol. Survey Bull. 38, p. 132, 1021; driller's record 1289 to 1565 feet. 184 APPENDIX C Deep Wells, Detailed Records — Continued 11. Toivn well, Milan, Rock Island County, Illinois,n center of the NE. % sec. 23, T. 17 N., R. 2 W. (Blackhawk Twp.) Altitude 566 feet Thickness Depth Feet Feet Recent and Pleistocene systems Drift 7 7 Devonian and Silurian systems, undifferentiated Cedar Valley and Wapsipinicon (Devonian) formations and Niagaran (Silurian) series Limestone, white, with some shale 383 390 Ordovician system Maquoketa formation Shale 160 550 Shale, with streaks of limestone 55 605 Mohawkian series Galena formation Limestone, brown 95 700 Limestone, white 140 840 Platteville formation Limestone, brownish 90 930 Glenwood formation Shale 30 960 St. Peter formation Sandstone 90 1050 Limestone, sandy 10 1060 Sandstone and limestone, with some shale 35 1095 Sandstone, hard and sharp 20 1115 Marl, red 10 1125 Prairie du Chien series Shakopee formation Limestone, white 32 1157 11 Record published in U. S. Geol. Survey Seventeenth Ann. Rept., pt. 2, p. 846, 1896. 12. Tri-City Railway Company's well in Prospect Park, Moline, 12 Rock Island County, Illinois, near center of east line of sec. S, T. 17 N., R. 1 W. (South Moline Twp.) Altitude 611 feet Recent, Pleistocene, and Pennsylvanian (?) systems, undifferentiated No record 71 71 Devonian system Cedar Valley and Wapsipinicon formations Limestone, calcareous, dense, pyritic ; sandy in upper part.. 60 131 Silurian system Niagaran series Dolomite, yellowish-white, grayish-white, bluish-white, and white, porous ; contains pockets of clay ; chert in lower part 350 481 Ordovician system Maquoketa formation Shale, sandy, gray, with tinges of buff, blue, and green ; pyritic 90 571 Shale, sandy, bluish-gray, with thin beds of limestone 30 601 Shale, gray and bluish-gray ; contains microscopical spherules (sand grains?) and pyrite crystals 60 661 Shale, dark gray, bituminous 50 711 12 Record to 1170 feet compiled from samples studied by J. A. Udden ; record below 1170 feet compiled from driller's record. APPENDIX C Deep Wells, Detailed Records — Continued Thickness Feet Mohawkian series Galena formation Dolomite, gray and yellowish-gray, granular, with some cnert and green clay 180 Platteville formation Limestone, yellowish-gray and bluish-gray, with some chert 150 Glenwood formation Shale, greenish-gray, with rounded grains of sand, chert, and pyrite 50 St. Peter formation Sandstone 50 Clay or shale, greenish, pyritic 20 Prairie du Chien series Limestone 449 Cambrian system Jordan formation Sandstone, sharp 30 Trempealeau formation Limestone, hard and soft 285 Mazomanie-Franconia formation Shale 25 Sandstone 30 Limestone 30 Dresbach formation Sandstone, hard, soft, and streaked 80 Eau Claire formation Shale, sandy 60 Shale 25 Limestone and shale 40 Shale, sandy 125 Mt. Simon formation Sandstone 28 13. Argillo Works well, Carbon Cliff, Rock Island County, Illinois,^ sec. ! t (?), T. R. 1 E. (Hampton Twp.) Altitude 592 feet Recent, Pleistocene, Pennsylvanian (?), and Devonian systems, un- differentiated No record 150 Silurian system Niagaran series Dolomite, white, with some sand and some gray shale 330 Ordovician system Maquoketa formation Shale, calcareous, green 120 Shale, calcareous, very dark, pyritic 80 Mohawkian series Galena and Platteville formations Dolomite, gray, granular, with some shale 135 No record 135 13 Record compiled from samples studied by J. A. Udden. 185 Depth Feet 891 1041 1091 1141 1161 1610 1640 1925 1950 1980 201O 2090 2150 2175 2215 2340 2368 17 N., 150 480 600 680 815 950 186 APPENDIX C Deep Wells, Detailed Records — Continued 14. City well, Orion, Henry County. Illinois, 1 * sec. 2S, T. 16 N., R. 1 E. Altitude approximately 750 feet, estimated from State geologic map Thickness Depth Recent and Pleistocene systems Feet Feet Loess, noncalcareous, brown, includes some till 80 80 Till, sandy, calcareous, dark gray , S3 163 No sample 17 180 Sand, calcareous, brown, medium-grained 5 185 Till, gravelly, calcareous, dark gray 5 190 Pennsylvanian system Pottsville formation Shale, black, soft 2 192 Shale, silty, gray, soft 38 230 Shale, dark gra}-, firm, micaceous 15 245 Sandstone, calcareous, gray, dense, fine-grained, pyritic... 31 276 Devonian system Cedar Valley and Wapsipinieon formations Limestone, brownish to light gray, granular 94 370 Shale, noncalcareous, light blue, fine-grained, with sub- rounded sand grains and chips of light gray, pink, and brown sandy dolomite 5 375 Silurian system Niagaran series Dolomite, light gray with dark gray spots, finely crystalline, dense or vesicular 30 405 Limestone, grayish-brown, coarsely granular, bituminous.... 15 420 Dolomite, white, buff, very finely or medium crystalline ; porous, vesicular, or dense 195 615 14 Record compiled from samples examined by L. E. Workman. 15. High School well, Sherrard, Mercer County. Illinois* 5 SE. % SW. % sec. k 3 T. 15 X., R. 1 W. (Richland Grove Tirp.) Altitude approximately 790 feet, estimated from Milan quadrangle topographic map Pleistocene and Pennsylvanian systems, undifferentiated No record 180 ISO Pennsylvanian system Pottsville formation Limestone and shale, calcareous 26 206 Coal (Rock Island No. 1) (thickness estimated) 5 211 No record 32 243 Devonian system Cedar Valley and Wapsipinicon formations Limestone 182 425 Devonian or Silurian system Sand, soft, blue (probably dolomitie sand) 23 44S Limestone, soft (probably dolomite) 2 450 15 Driller's record. 16. Village well No. 1, Woodhull, Henry County, Illinois™ NW. M sec. SO, T. 1', X R. 2 E. (Clover Twp.) Altitude approximately 854 feet, estimated Pleistocene and Pennsylvanian systems, undifferentiated Drift and shale 160 Pennsylvanian system Carbondale ( ?) and Pottsville formations Shale 23 "Fireclay" (includes sandstones, shales, etc.) 192 160 183 375 lfl Driller's record. APPENDIX C 187 Deep Wells, Detailed Records — Continued Thickness Depth Feet Feet Mississippian system ( ?) Sweetland Creek formation (?) Shale 35 410 Devonian system Cedar Valley and Wapsipinicon formations Limestone 131 541 Shale 59 600 Silurian system Niagaran series Limestone 225 825 Ordovician system Maquoketa formation Shale 185 1010 Mohawkian series Galena and Platteville formations Limestone 280 1290 St. Peter formation Sandstone 104 1394 17. Village well No. 2, Wooclhull, Henry County, Illinois,™ NE. % SW. % sec. 30, T. U N., R. 2 E. (Clover Twp.) Altitude approximately 824 feet, estimated from State geologic map Pleistocene system Glacial drift 100 100 Pennsylvanian system Carbondale (?) and Pottsville formations Shale, silty, slightly calcareous or noncalcareous, medium gray, micaceous, very soft 45 145 Shale, calcareous, dark gray to black, noncarbonaceous, non- laminated, tough or soft 15 160 Shale, noncalcareous, medium gray, soft, with coal 5 165 Underclay, light gray, soft, micaceous ; contains many pieces of yellowish-brown, granular, fine-grained limestone 10 175 Underclay, silty, light gray, soft, micaceous 15 190 Shale, dark gray, soft, and some black laminated, brittle... 5 195 Shale, silty, light yellowish-gray, brownish-gray, and dark gray, soft, with coal at base 30 225 Shale, silty, dark gray to black, micaceous, with streaks of light gray, argillaceous siltstone 25 250 Underclay, silty, medium brownish-gray, soft, micaceous ; coal, shaly, impure, dull ; siltstone argillaceous, light gray ; and dolomite, argillaceous, brown, tough 15 265 Shale, dark and light gray, micaceous, poorly laminated ; locally calcareous and concretionary 65 330 Sandstone, calcareous, medium gray, pyritic, grains fine to medium, poorly sorted 5 335 Shale, dark and light gray 5 340 Sandstone, calcareous, well cemented, dense, pyritic 5 345 Shale, silty, dark and medium gray, nonlaminated 15 360 Sandstone, dolomitic, pyritic : grains are fine, clear, and angular or rounded, frosted 5 365 Mississippian system Sweetland Creek formationa Shale, silty, sandy, dolomitic ; black, light gray, micaceous and pyritic, contains Sporangites huronense 15 380 17 Record derived from samples studied by L. E. Workman. a Although the Sweetland Creek formation is assigned to the Mississippian System, it may belong in the Devonian System. 188 APPENDIX C Deep Wells, Detailed Records — Continued Thickness Feet Devonian system Cedar Valley and Wapsipinicon formations Limestone, dolomitic ; finely sandy, silty, and argillaceous ; light gray, brownish and buff ; finely granular, porous, some gray, silty shale ; pyritic 100 Limestone, slightly dolomitic, light gray and buff, finely to coarsely granular, porous, and some shale, brown Shale, silty, slightly dolomitic, light gray, soft Dolomite, light gray, fine-grained, mixed with gray shale.. Shale, noncalcareous, medium gray, waxy, brittle Shale, gray, waxy, brittle and shale, silty, noncalcareous, black, nonlaminated, tough Silurian system Niagaran series Dolomite, light gray and white, finely crystalline Ordovician system Maquoketa formation Shale, silty, calcareous, light bluish-gray, porous, pyritic. . Siltstohe, very argillaceous, calcareous, light bluish-gray, finely cross-bedded Shale, silty, calcareous, medium gray, and grayish-brown . . Mohawkian series Galena and Platteville formations Dolomite, light brown to light buff, fine-grained, crystalline, slightly porous Glenwood formation Sandstone, dolomitic, white, and buff, fine to medium round frosted and angular glassy grains 32 St. Peter formation Sandstone, white, grains, fine and coarse, rounded 69 10 170 70 18 127 303 Depth Feet 480 40 520 5 525 35 560 10 570 580 750 120 838 965 1268 1300 1369 18. Chicago, Burlington and Quincy Railroad well, Alpha} s Henry County, Illinois, SE. r A NE. % sec. 21, T. Ik N., R. 1 E. (Oxford Twp.) Altitude approximately 800 feet Pennsylvanian system Carbondale ( ?) and Pottsville formations "Slate'' (shale) and coal (probably includes some glacial drift at top ) Clay, gray Limestone Shale, black "Black material" (shale and coal?) "Sticky formation" (shale) Sandstone Pennsylvanian or Mississippian system Pottsville (Pennsylvanian) formation or Sweetland Creek (Mis- sissippian) formation "Soapstone'' (shale) Mississippian system Sweetland Creek formation Shale, white Devonian and Silurian systems Cedar Valley and Wapsipinicon (Devonian) formations and Niagaran (Silurian) series Limestone 92 92 26 118 12 130 20 150 75 225 40 265 10 275 15 325 350 365 690 18 I )riller's record. 50 1260 10 1270 70 1340 4 1344 APPENDIX C 189 Deep Wells, Detailed Records — Continued Thickness Depth Feet Feet Ordovician system Maquoketa formation Shale 200 890 Mohawkian series Galena and Platteville formations Limestone 320 1210 Gienwood formation Sandstone Shale St. Peter formation Sandstone Shale Prairie du Chien series Shakopee formation Limestone, brown and red 20 1364 19. City well, Viola, Mercer County, Illinois™ NE. % SE. y± sec. 15. T. 1^ X., R. 2 W. (Greene Twp.) Altitude 790 feet Recent and Pleistocene systems Surface soil Sand Clay, blue, and fine sand Pennsylvanian system Pottsville formation Shale Limestone Shale and limestone Shale, sand3 T "Slate" Cshale), blue "Slate'' (shale), black Shale, white, and limestone Shale, black Shale, (may be Sweetland Creek formation) Devonian system Cedar Valley and Wapsipinicon formations Limestone and shale (may include some shale of Sweetland Creek formation) Limestone Shale Limestone Silurian system Xiagaran series Limestone and shale Limestone Ordovician system Maquoketa formation Shale Shale and limestone Limestone, brown Shale, brown Mohawkian series Galena and Platteville formations Limestone, brown St. Peter formation Sandstone lo 15 27 42 58 100 15 115 15 130 10 140 5 145 37 182 18 200 25 225 20 245 5 250 50 300 40 340 4 344 106 450 91 541 109 650 75 725 50 7 75 50 S25 25 S50 306 1156 127 12S3 19 Driller's record. 190 APPENDIX C Deep Wells, Detailed Records — Continued 20. City well Xo. 1. Aleclo, Mercer County, Illinois. 20 SW. come)- SW. J4 SE. J/4 sec. 17, T. U X., JR. S W. (Mercer Twp.j Altitude 739 feet Thickness Feet Recent and Pleistocene sj'Stems Clay Coal ( probably in drift ) Clay, blue Pennsylvania!) system Pottsville formation "Soapstone" ( shale ) "Slatestone'' ( shale) Coal Tvlississippian system Sweetland Creek formation "Soapstone" (shale, may include some Pennsylvanian shale and also probably includes some argillaceous limestone of Devonian age) Devonian system Cedar Valley and Wapsipinicon formations "Fireclay" (probably shaly limestone, white) "Sandstone" (probably dolomite) Limestone "Quartz rock" (probably cherty limestone or dolomite).... Shale., calcareous, bluish-gray "Slate" (shale) Shale, black Silurian system Xiagaran series Dolomite, gray, sandy Dolomite, light gray .- Ordovician system ZMaquoketa formation Limestone, shaly Shale, calcareous, gray Limestone, dolomitic, with a small amount of shale Shale, calcareous, finer grained than above Limestone, ( dolomite) Shale, calcareous, gray Limestone, gray Shale, slightly calcareous, gray Mohawkian series Galena and Platteville ( ?) formations Limestone, dolomitic. gray Dolomite, calcareous, gray Decorah (?) formation Shale, slightly calcareous, gray Platteville formation Dolomite, light gray, with some shale Glen-wood formation Sandstone, very finely grained, cream-colored, with a little dolomite Dolomite, gray, and sandstone Shale, sandy, slightly dolomitic. very fine-grained, gray St. Peter formation Sandstone, white Sandstone, light yellow Sandstone, slightly dolomitic, gray 70 163l; Depth Feet 110 5 155 5 160 1% 161 1 : 325 "•Compiled from driller's record and samples of well cuttings studied by 25 350 10 360 15 375 55 430 10 440 5 445 1 446 6 452 140 592 8 600 71 671 15 6S6 20 706 10 716 39 755 15 770 37 807 3 810 250 1060 10 1070 50 1120 10 1130 2 5 1155 25 1180 35 1215 10 12 2 5 15 1240 T. E. Savage. APPENDIX C 191 Deep Wells, Detailed Records — Continued Prairie du Chien series Shakopee formation Dolomite, gray, with a little white sand Dolomite, gray Dolomite, gray, with considerable shale Limestone, dolomitic, very light gray, with some sandstone. Limestone, chocolate-colored, with some fine-grained shale. Limestone, slightly dolomitic, light buff-colored Limestone, dolomitic New Richmond formation Sandstone, calcareous, chocolate-colored Sandstone, calcareous, light brown Sandstone, white Sandstone, dolomitic, light buff-colored and gray Oneota formation Dolomite, grayish-white Dolomite, slightly sandy, grayish Sandstone, cherty, gray Dolomite, sandy, very fine-grained, grayish-white Dolomite, gray, slightly sandy Dolomite, slightly calcareous, grayish-white, with some sand Dolomite, slightly calcareous, light buff-colored Cambrian system Jordan formation Sandstone, slightly dolomitic, light gray, to buff Sandstone, "blue"' Trempealeau formation Shale, calcareous, chocolate-colored Dolomite, gray, with a little dark shale Shale, calcareous and dolomitic, chocolate-colored. ....... . Dolomite, light brown Mazomanie-Franconia formation Sandstone, white Limestone and shale Shale, blue, with dolomite, slightly sandy, at base light brown Dolomite, gray, sandy Shale, gray, dolomitic Shale, gray, dolomitic, sandy Dresbach formation Sandstone, gray, some dolomite Sandstone, gray, fine-grained Sandstone, fine-grained, white Sandstone, flesh-colored, fine-grained Sandstone, light brown, fine-grained Eau Claire formation Shale, sandy, gray, hard Shale, calcareous, light gray Shale, dark, hard, gray Mt. Simon formation Sandstone, dark brown, fine-grained Sandstone, flesh-colored and white Sandstone, pink and gray, fine-grained Sandstone, red, fine-grained Sandstone, white, hard Thickness Depth Feet Feet 15 1255 25 1280 5 1285 40 1325 5 1330 25 1355 10 1365 15 1380 10 1390 5 1395 75 1470 5 1475 72 1547 5 1552 5 1557 83 1640 22 1662 13 1675 50 1725 40 1765 140 1905 10 1915 30 1945 15 1960 5 1965 10 1975 37 2012 73 2085 40 2125 40 2165 10 2175 55 2230 45 2275 25 2300 15 2315 65 2380 10 2390 67 2457 113 2570 50 2620 175 2795 276 3071 43 3114 192 APPENDIX C Thickness Depth Feet Feet 55 55 10 65 10 75 10 85 15 100 5 105 9 114 1 115 10 125 10 135 Deep Wells, Detailed Records — Continued 21. City Well No. 2, Aleclo, Mercer County, Illinois,^ SW. corner SW. ]/ 4 SE. |/ 4 sec. 17, T. U N., R. 3 W. (Mercer Twp.J; 200 feet from city Well No. 1 Altitude 736.2 feet Recent and Pleistocene systems Till, pebbly and sandy, dolomitic, greenish-gray to brownish- yellow Clay, calcareous, dark gray Gravel Clay, silty, calcareous, brownish-gray Till, pebbly, slightly dolomitic, brownish-yellow Pennsylvanian system Pottsville formation Shale, slightly calcareous, light gray, soft Clay ( shale ) , black Limestone, argillaceous, dark bluish-gray and brown "Clay" (shale), black Shale, dark gray to black, carbonaceous Mississippian system Sw T eetland Creek formation Shale, slightly calcareous, light gray, contains Sporangites huronense Shale, slightly calcareous, brownish-gray, contains Spor- angites huronense Shale, calcareous, gray and brown to chocolate-colored, con- tains Sporangites huronense Devonian system Cedar Valley and Wapsipinicon formations Dolomite, argillaceous, gray, finely granular, porous Limestone, brownish-gray, fineljr to medium granular, porous, fossilif erous Limestone, argillaceous, gray, finely granular, fossiliferous, with green, waxy shale at top Shale, white Limestone, argillaceous, gray, finely granular, fossiliferous. Dolomite, calcareous, light gray, very finely crystalline, porous Shale, gray, soft, contains Sporangites huronense Silurian system Niagaran series Dolomite, light to dark gray, finely crystalline to dense, vesicular Dolomite, light cream-gra3 r with dark spots, finely crystal- line Ordovician system Maquoketa formation Shale, dolomitic, medium to light bluish-gray Dolomite, gray with dark pyritic spots, fine-grained Shale, dolomitic, light bluish-gray Shale, dolomitic, light brown Dolomite, argillaceous, brownish-gray Shale, dolomitic, dark brown Mohawkian series Galena and Platteville (?) formations Dolomite, light brown, finely crystalline Dolomite, buff, finely crystalline, cherty Dolomite, light gray and white Dolomite, white and brown, pyritic, brown portion is porous 80 20 3 20 2 45 5 10 215 235 265 285 305 350 355 365 428 430 65 495 65 560 73 633 15 648 50 698 35 733 10 743 20 763 5)2 855 95 950 15 965 30 995 21 Record compiled from samples studied by L. K. Workman. APPENDIX C 193 Deep Wells, Detailed Records — Continued Decorah ( ?) formation Shale, dolomitic, green Platteville formation Limestone, brown to light buff, dense to medium-grained... Dolomite, brownish-gray with dark spots, fine, sandy at bottom Glenwood formation Sandstone, dolomitic, light brownish-gray ; fine, rounded grains Shale, bluish-gray, waxy St. Peter formation Sandstone, white, medium-grained, rounded grains Sandstone, white, medium-grained ; dolomite, sandy, fine- grained, light brownish-gray ; chert, white and buff, some oolitic ; and shale, light blue Prairie du Chien series Shakopee formation Dolomite, sandy, brownish-gray Thickness Depth Feet Feet 5 1000 10 1010 40 1050 40 1090 15 1105 30 25 12 1135 1160 1172 22. Oil test boring, Mercer County, Illinois/ 2 NW. y± NW. % sec. 2, T. 13 N„ (Sues Twp.) Altitude 733 feet Recent and Pleistocene systems Clay (till) 40 "Hardpan'' (dense till), light gray 50 No record (till with boulders) 40 Pennsylvanian system Pottsville formation "Slate" (shale), white 5 "Soapstone" (shale), blue 40 Mississippian system Sweetland Creek formation Shale, brown 150 Devonian system Cedar Valley and Wapsipinicon formations Limestone, brown 55 Limestone, gray 45 No record 15 Silurian system Niagaran series Dolomite, gray 15 Limestone, gray (dolomite) 151 Dolomite, gray 4 Ordovician system Maquoketa formation Shale, white 77 Limestone, blue 20 Shale, white 20 Shale, brown 4 4 Shale, red 31 Mohawkian series Galena and Platteville formations Dolomite, gray, and brownish, subcrystalline 251 Limestone, dark gray 55 R. 2 W. 40 90 130 135 175 325 380 425 440 455 606 610 687 707 727 771 802 1053 1108 22 Record compiled from driller's record and samples of well cuttings studied by T. E. Savage. 194 APPENDIX C Deep Wells, Detailed Records — Continued Thickness Depth Feet Feet Glenwood formation Dolomite, grayish or brownish, with a few quartz grains.... 5 1113 Sandstone, gray, with some dolomite 21 1134 St. Peter formation Sandstone 18 1152 23. Oil-test well, Mercer County. Illinois. 23 SW. % sec. 19. T. 13 N., R. 2 W. (Suez Twp.) Altitude 635 feet Recent and Pleistocene systems Soil, glacial drift 40 40 Pennsylvanian and Mississippian systems Pottsville (Pennsylvanian) and Sweetland Creek (Mississippian) formations "Soapstone" (shale), with pyrite 155 195 Devonian system Cedar Valley and Wapsipinicon formations Limestone, dolomitic, gray, pyritic Limestone, light gray, fine and coarse textured, with chert fragments Limestone, dolomitic at top and bottom, gray, with some chert Silurian sj^stem Niagaran series Limestone, light gray, with fragments of dull brown dolomite Dolomite, crystalline, dull, brown Dolomite, light and dark gray, crystalline Dolomite, fine-grained, very light gray, with some pyrite.. Dolomite, fine-grained, light gray, cherty, pyritic Ordovician system Maquoketa formation Shale gray to greenish-gray, with dolomite Dolomite, shaly, gray Shale, gray, with a little dolomite Shale, dolomitic, gray to drab Limestone, dolomitic, gray to drab Limestone, shaly, dolomitic, light drab Dolomite, shaly, gray Shale, dolomitic, gray Dolomite, slightly shaly, gray, fine-grained Dolomite, shaly, drab, with pyrite at base Limestone, dolomitic, gray and dark, subcrystalline, with considerable pyrite 10 640 Galena and Platteville (?) formations Dolomite, light brownish-gray, subcrystalline 65 705 Dolomite, gray, with fragments of white chert 175 880 Decorah ( ?) formation Dolomite, gray, with a few grains of quartz sand 5 885 35 230 50 280 40 320 10 330 10 340 35 375 10 385 60 445 5 450 5 455 5 460 45 505 15 520 5 525 5 530 10 540 20 560 70 630 23 Record derived from samples studied by T. E. Savage. APPENDIX C 195 Deep Wells, Detailed Records — Continued 24. Chicago, Burlington and Quincy Railway well, 2i Knox County, Illinois/ NE. % sec. 3 $ (?), T. IS N., R. 1 E. (Rio Twp.) Altitude 810 feet Thickness Depth Feet Feet No record (includes glacial drift [Pleistocene], Pottsville [Pennsylvanian] formation, and probably Sweetland Creek [Mississippian] formation). Rock (Devonian) at 375 375 No record (includes Cedar Valley and Wapsipinicon [De- vonian] formations, Niagaran [Silurian] series, and Ma- quoketa [Ordovician] formation) 525 900 Ordovician system Galena, Platteyille, and Glenwood formations Limestone 400 1300 St. Peter formation Sandstone 20 1320 24 Skeleton record supplied by Division Engineer of railway. 25. City well, Alexis, Warren County, Illinois, 25 NW. corner NE. y$ NE. V^ sec. 1, T. 12 N., R. 2 W. (Spring Grove Twp.) Altitude 704 feet Recent and Pleistocene systems Loam and yellow clay 30 30 Clay, blue 35 65 Pennsylvanian system Pottsville formation Sandstone 40 105 "Soapstone" (shale), blue 5 110 Limestone streak 110 Pennsylvanian and Mississippian systems, undifferentiated Pottsville (Pennsylvanian), Hannibal (Mississippian), and Sweet- land Creek (Mississippian) formations Shale, blue 238 348 Devonian and Silurian systems, undifferentiated Cedar Valley and Wapsipinicon (Devonian) formations and Ni- agaran (Silurian) series Limestone and dolomite 222 570 Ordovician system Maquoketa formation Shale 120 690 Shale and limestone 40 730 Mohawkian series Galena and Platteville formations Limestone 326 1056 St. Peter formation Sandstone 144 1200 25 Driller's record. 196 APPENDIX C Deep Wells, Detailed Records — Continued 26. Farm well, SE. corner NE. % NE. ~hi sec. 29, T. 12 N., R. 2 W. (Spring Grove Twp.J, Warren County, Illinois 25 Altitude 703 feet Thickness Depth Feet Feet Recent and Pleistocene systems Surficial material 30 30 Pennsylvanian system Pottsville formation Sandstone 5 35 Coal "blossom" 35 Underclay, white 60 95 Sandstone 95 Mississippian system Hannibal and Sweetland Creek formations "Soapstone" (shale) 210 305 Devonian and Silurian systems, undifferentiated Cedar Valley and Wapsipinicon (Devonian) formations and Niagaran (Silurian) series Limestone 220 525 Ordovician system Maquoketa formation Shale, blue, plastic, pyritic 2 527 26 Driller's record. 27. Oil-test well, Henderson County, Illinois, 2 ' NW. % NE. % NE. Y± sec. 1, T. 12 N., R. 5 W. (Bold Bluff Twp.J Altitude approximately 590 feet Recent and Pleistocene systems Sand and gravel 220 220 Devonian system Cedar Valley and "Wapsipinicon formations Limestone, dolomitic, argillaceous, gray and brown, finely crystalline 131 351 Silurian system Niagaran series Dolomite, cherty, light buff-gray, finely crystalline 59 410 Ordovician system Maquoketa formation Shale, silty, slightly dolomitic, bluish-gray 28 438 Shale, silty, dolomitic, grown and gray ; and dolomite, gray, finely crystalline 8 446 Shale silty, dolomitic, brown and gray 138 584 Shale, dolomitic, gray, and dolomite, argillaceous, brownish- gray, crystalline 26 610 Mohawkian series Galena formation Dolomite, buff, finely crystalline 40 650 No record; probably dolomite 190? 840 Platteville formation Dolomite, argillaceous, reddish-brown, very finely crystalline ? No record; probably dolomitic limestone 116 956 St. Peter formation Sandstone 956 27 Record compiled from samples of well cuttings studied by L. E. Workman. APPENDIX C 197 Deep Wells, Detailed Records — Continued 28. City well No. 2 (old), Monmouth, Warren County, Illinois™ center of S. Y 2 N. y 2 sec. 29, T. 11 N„ R. 2 W. Altitude slightly less than 740 feet, according to Monmouth quadrangle topographic map Thickness Depth Feet Feet Recent and Pleistocene systems Soil, loessial, clayey, sandy Clay, (till) sandy, yellow Sand, and clay, yellow Silt, yellow, buff, and drab Clay (till), sandy, yellow Sand and gravel, yellow Pennsylvanian system Pottsville formation Shale, soft, drab, with fine sand Shale, gray or drab, pyritic Mississippian system Burlington formation Limestone, gray, cherty, occasional crinoid stems Limestone, dolomitic, porous Limestone, dolomitic, cherty Hannibal formation Shale, calcareous, greenish-gray, with crinoid stems and pyrite Sweetland Creek formation Shale, black or dark gray, contains Sporangites huronense. Dolomite, finely granular, and some shale Devonian system Cedar Valley and Wapsipinicon formations Limestone, pyritic, mixed with shale Limestone , Shale, gray, , stony, with fragments of fossils Limestone, shaly, gray Limestone, gray Limestone, white, dense, brittle (may be Silurian) Silurian system Niagaran series Limestone, dolomitic, gray, dense Ordovician system Maquoketa formation Shale, bluish-gray, pyritic at top Shale, dark gray, with spherical concretions of pyrite and fragments of black, bituminous limestone Shale, gray Shale, dark gray, granular Limestone, dolomitic, gray Dolomite, shaly, dark Limestone, dolomitic, dark brownish-gray Limestone, dolomitic, shaly, greenish-gray Limestone, dolomitic, dark gray Limestone, dolomitic, some gray, some straw-colored, and some greenish ; pyritic Mohawkian series Galena and Platteville formations Limestone, dolomitic, dull straw-colored Limestone, dolomitic, dull straw-colored with some green shale Limestone, dolomitic straw-colored Limestone, dolomitic, cream-colored, with some white chert. Limestone, dolomitic, cream-colored 28 Compiled from samples studied by J. H. Southwell and J. A. Udden. 2 2 12 14 4 18 16 34 3 37 16 53 14 67 5 72 83 155 5 160 8 168 122 58 31 15 75 290 39 429 15 444 28 472 6 478 5 483 34 517 5 522 5 527 585 616 5 621 33 654 7 661 27 688 10 693 39 737 9 746 19 765 •so 855 9 864 2 876 4 890 5 895 198 APPENDIX C Deep Wells, Detailed Records — Continued Thickness Depth Feet Feet Shale, green 5 900 Limestone, dolomitic, shaly, cream-colored, cherty 35 935 Limestone, dolomitic, cream-colored, somewhat porous 37 972 Limestone, dolomitic, shaly, cream-colored, pyritic 32 1004 Limestone, dolomitic, cream-colored, with fragments of black rock containing "about 50 per cent bitumen 11 1015 Limestone, dolomitic, cream-colored, cherty 7 1022 Limestone, dolomitic, dull brown, with some chert and some green shale 13 1035 Limestone, dolomitic, gray, with some gray chert 15 1050 Limestone, dolomitic, dull straw-colored, with some white limestone 3 1053 Limestone, dull straw-colored 7 1060 Limestone, somewhat dolomitic, gray 9 1069 Limestone, dolomitic, gray, with some green, shale marked by foliated black blotches (Glen wood?) 5 1074 St. Peter formation Sandstone; coarse to medium fine rounded grains of quartz 139 1213 Sandstone, moderately coarse grains, and green shale 5 1218 Sandstone, coarse, rounded, quartz grains 3 1221 Sandstone, fine, quartz grains 4 1225 Sandstone, coarse grained, and green shale 5 1230 Prairie du Chien series Shakopee formation Limestone, dolomitic, white, with some sand.... 2 1232 29. City well No. J t (Geiger No. 1) Monmouth. Warren County, Illinois, 2 * SW. corner sec. 29, T. 11 N., R. 2 W. Altitude 769 feet Recent, Pleistocene, and Pennsylvanian systems, and probably some of Mississippian system No record 135 135 Mississippian system Burlington formation Limestone, dolomitic, greenish-buff, finely crystalline, crin- oidal, very cherty 20 155 Limestone, dolomitic, greenish-buff, finely crystalline, porous, little chert 35 190 Hannibal formation Shale, calcareous, light bluish-gray with black laminae 90 280 Sweetland Creek formation Shale, dolomitic, brown and brownish-gray with greenish- gray and black laminae, contains Sporangites huronense, abundant in lower 45 feet 105 385 Shale, dolomitic, light brownish-gray contains a few Spor- angites huronense 80 465 Devonian system Cedar Valley and "Wapsipinicon formations Limestone, dolomitic sandy, buff, finely granular, porous, soft 50 515 Limestone, argillaceous, sandy, medium gray with dark spots, finely to coarsely granular 45 560 Silurian system Niagaran series Dolomite, light gray, finely crystalline, dense 20 580 Dolomite, light gray, finely crystalline, porous, contains white chert 20 600 29 Compiled from samples studied by L. E. Workman. APPENDIX C 199 Deep Wells, Detailed Records — Continued Thickness Depth Feet Feet Ordovician system Maquoketa formation Shale, dolomitic, light gray and brown, and siltstone, argil- laceous, dolomitic, brownish-gray 70 670 Dolomite, argillaceous, brown and light gray : shale, dolo- mitic, brown and greenish-gray ; siltstone, dolomitic, ar- gillaceous, brownish-gray 85 755 Mohawkian series Galena and Platteville formations Dolomite, brownish-gray, finely crystalline, dense 205 960 Dolomite, light brownish-gray and pink, finely crystalline, dense 10 970 Dolomite, light gray and pink, finely crystalline, dense, cherty 40 1010 Dolomite, brownish-gray, finely crystalline, with white and light brown chert 100 1110 St. Peter formation Sandstone, white ; medium, rounded to angular, frosted grains; a few chips of bluish-gray shale 150 1260 Shale, sandy, bluish-gray, light green 8 1268 Sandstone, coarse grained ; and shale, light gray, interlam- inated with white, fine-grained sandstone 7? 1275 Prairie du Chien series Dolomite, sandy, light gray, and pinkish-gray, fine-grained, dense, cherty, with green shale 225 1500 Dolomite, white to light gray, finely crystalline, vesicular, cherty 170 167.0 Dolomite, white and light gray, pinkish, medium crystalline, vesicular, very cherty 130 1800 Cambrian system Jordan formation Sandstone, dolomitic, fine to medium grained, and dolomite, very sandy, finely crystalline, white and light pinkish-gray 30 1830 Trempealeau formation Dolomite, sandy, light to medium gray with pink and tan tints, tan, finely crystalline, dense 225 2055 Dolomite, light gray, and pink, finely crystalline, glauconitic 35 2090 Mazomanie-Franconia formation Dolomite, very sandy, light greenish-gray ; finely crystalline, contains much glauconite 20 2110 Sandstone, greenish-gray to green, very fine grained, compact, very glauconitic Dolomite, sandy, light bluish-gray, finely crystalline Sandstone, dolomitic, gray, very fine grained, glauconitic, interlaminated with shale, sandy, dolomitic. glauconitic, gray, and greenish-pink, buff, very fine Sandstone, dolomitic, light brownish-gray, medium to fine, angular to rounded grains, little or no glauconite Dresbach formation Sandstone, slightly dolomitic, light brownish-gray, buff and white, medium to coarse, angular to rounded grains 100 244! 125 2235 30 2265 45 2310 35 2345 200 APPENDIX C Deep Wells, Detailed Records — Continued 30. City well No. 5 (Geiger No. 2), Monmouth, "Warren County, Illinois/ SW. corner sec. 29, T. 11 N., R. 2 W. Altitude 769 feet dark gray, soft..... brown, soft blue, soft gray, hard blue, hard , hard, and limestone. Recent and Pleistocene systems Drift Pennsylvanian system Pottsville formation Coal Shale Mississippian system Burlington formation Limestone, gray, soft . . Hannibal formation Shale, gray, soft Shale, blue Shale, gray, hard Shale, blue, soft Sweetland Creek formation Shale, gray, hard Shale, Shale, Shale, Shale, Shale, Shale, Devonian system Cedar Valley and Wapsipinicon formations Limestone, brown, hard Silurian system Niagaran series Limestone, light gray, hard Limestone, gray and brown Ordovician system Maquoketa formation Shale, light colored, soft... Shale, dark, hard Limestone, dark, hard Limestone and shale, hard Mohawkian series Galena formation Limestone, brown, hard Piatt eville ( ?) formation Limestone, gray, hard Decorah ( ?) formation Shale, soft Platteville formation Limestone, brown, hard St. Peter formation Sandstone, dark gray, hard Sandstone, white, soft Sandstone, white, hard Shale, blue, soft Limestone, shaly, and sandstone; hard. Shale, green, soft Shale, sandy, soft Prairie du Chien series Limestone, brown, and gray, hard Limestone, pink, hard Thickness Feet 9 5 1 14 80 95 218 41 58 Depth Feet 95 110 20 210 30 240 10 250 30 280 20 300 30 330 30 360 80 440 10 450 5 455 20 475 570 10 580 30 610 45 655 35 690 78 768 12 780 1039 1042 1100 70 1170 75 1245 5 1250 4 1254 6 1260 5 1265 10 1275 75 1450 50 1500 30 Driller's record. APPENDIX C 201 Deep Wells, Detailed Records — Continued Thickness Depth Feet Feet Limestone, brown and gray, hard 50 1550 Sandstone, white, soft 5 1555 Ordovician and Cambrian systems, undifferentiated Prairie du Chien (Ordovician) series and Jordan, Trempealeau, and Mazomanie-Franconia (Cambrian) formations Limestone, gray and brown, hard 740 2295 Cambrian system Mazomanie-Franconia formation Sandstone, gray, hard 35 2330 Dresbach formation Sandstone, white, soft 80 2410 Sandstone, white and dark, "shelly'' (dolomitic and shaly) . 35 2445 31. City well (Geiger well No. 1), Galesbvrg, Knox County, Illinois/ 1 NE. % NE. % sec. 15, T. 11 N., R. 1 E. (Galesburg Twp.) Altitude 754.10 feet Recent and Pleistocene systems No record 50 50 Sand, yellowish-brown and brownish-gray, medium-grained, calcareous in lower part 45 95 Pennsylvanian system Carbondale and Pottsville formations Shale, silty, calcareous, medium gray 20 115 Shale, very silty, non-calcareous and very calcareous, with streaks of limestone, greenish-gray 5 120 Shale, silty, more or less sandy with fine grains, calcareous, medium gray, with some coal locally at 150 and 165 feet.. 70 190 Coal, and underclay, light gray, soft 10 200 Shale, dark gray, soft 30 230 Shale, slightly sandy, slightly calcareous, grayish-brown, with chert 15 245 Mississippian system Sweetland Creek formation Shale, light gray and brown 20 265 Shale, slightly gritty, brown and gray, with Sporangites huronense 55 320 Devonian system Cedar Valley and Wapsipinicon formations Limestone, argillaceous, light brownish-gray 110 430 Silurian sj^stem Niagaran series Chert, white and gray, oolitic and banded, some weathered. 5 435 Dolomite, light gray, powdered 15 450 Silurian and Ordovician systems, undifferentiated No record (includes about 100 feet of Niagaran [Silurian] series, about 200 feet of Maquoketa [ Ordovician 1 series, and about 50 feet of Galena [Ordovician] formation) 350 800 Ordovician system Mohawkian series Galena and Platteville formations Dolomite, buff, finely crystalline 245 1045 Glenwood formation Dolomite, sandy, buff ■ 15 1060 St. Peter formation Sandstone, white, fine to medium grained 130 1190 31 Record derived from samples studied by L. E. Workman. 202 APPENDIX C Deep Wells, Detailed Records — Continued Thickness Depth Feet Feet Chert pebbles, white and buff, oolitic, dense and porous ; with sandstone and green shale 35 1225 Shale, sandy, green, with chert and sandy dolomite 5 1230 Prairie du Chien series Shakopee formation Dolomite, gray, buff and pink, with cherty and sandy layers 205 1435 Dolomite, light brown, with whitish chert 50 1485 New Richmond ( ?) formation Sandstone, dolomitic, very fine to medium-grained ...•■ 25 1510 Oneota formation Dolomite, cherty, light, gray to white 215 1725 Cambrian system Jordan ( ? ) formation Dolomite, sandy, cherty, white, with sandstone, white, fine- grained 10 1735 Trempealeau formation Dolomite, light gray and pink, very fine-grained, with sand grains at some horizons 285 2020 Dolomite, light brownish-gray, glauconitic 10 2030 Mazomanie-Franconia formation Sandstone, very glauconitic, light gray, with greenish tint; very fine, angular grains; dolomitic cement 130 2160 Dolomite, sandy, gray, with sandstone, glauconitic 30 2190 Sandstone, dolomitic, glauconitic, gray 25 2215 Shale, dolomitic, glauconitic, yellow-green, mixed with sand- stone 20 2235 Dresbach formation Sandstone, white and yellow ; fine to coarse, rounded grains, loosely cemented with dolomite 70 2305 Farm Wells (Logs of wells 32-84 are shown graphically on Plate VI) Key Location by Thick- No. township and Alti- Description and correlation ness Depth on quarter section tude Feet Feet map Key: 1, Recent and Pleistocene systems; 2, Pennsylvanian system — A, Carbon dale formation, B, Pottsville formation; 3, Mississippian system — A, Burlington forma- tion, B, Hannibal formation, C, Sweetland Creek formation; 4, Devonian system, Cedar Valley and Wapsipinicon formations, (may include part of 5); 5, Silurian system, Niagaran series. 32 \y.\ Mercer County T. 15 N., R. 1 W. (Richland Grove Twp.) 31 SW SE SW 722 1, 2, 3 4, 5? T. 14 N., R. 1 W (Rivoli Twp.) 4 SW SE 794 1. 2B, 3C. 34c 13 808 (est) No record 206 Limestone ; hard and white at base 130 "Blue sand" Loess and drift ". . 80 Shale, underclay, and beds of rock (sandstone and limestone) 171 Limestone, with some chert at depth of 385 feet 178 206 336 336 80 251 429 c Log of city well, New Windsor ; record derived from samples studied by G. E. Ekblaw. APPENDIX C 203 Farm Wells — Continued Key Location by Thick- No. township and Alti- Description and correlation ness Depth on quarter section tude Feet Feet map 1 a. b. 2Ba. m. 4 a. b. c. No record Till, sandy and pebbly, calcareous, dark brownish-gray Sand, with some till Till, sandy and pebbly, calcar- eous, dark brownish-gray Gravel, fine, and coarse sand, mainly quartz and chert, tan- colored Till, silty, calcareous, light bluish- gray, greenish, or brownish, dense Gravel, fine and coarse, and sand Sandstone, faintly dolomitic, fine- grained, gray, pyritic, micaceous ; and siltstone, non-calcareous, light gray-green and black, with dark carbonaceous partings Shale, bluish-black or dark bluish- gray, laminated, pyritic Shale, bluish-black, with silt- stone and fine-grained sandstone, calcareous, gray, pyritic Shale, gray, with carbonized plant fragments Shale, gray, soft or dark blue- black and brown, dense, hard, with carbonized plant fragments Shale, black, hard, laminated.... Shale and siltstone, noncalcar- eous, gray mottled with brown. . Shale and siltstone, carbonaceous, dark gray, with gray, fine- grained, quartzitic sandstone and black, hard, laminated shale.... Siltstone, calcareous, fine-grained, light greenish-gray Shale, soft and greenish-gray ; or , hard and bluish-black Sandstone, fine-grained, pyritic, with hard, brittle, black shale and siltstone Sandstone, fine-grained, dark gray, with soft green shale and white chert Shale, hard, laminated, black or gray-green, with quartz and chert Limestone, sandy, brownish-gray, granular, very fossiliferous Limestone, argillaceous, bluish- gray, finely granular Limestone, argillaceous, dark bluish- gray, or buff-gray, cherty. 15 15 90 95 15 110 10 120 15 135 10 145 95 240 15 255 10 265 10 275 20 295 5 300 15 315 20 335 5 340 5 345 10 355 5 360 5 365 20 385 20 405 30 435 204 APPENDIX C Farm Wells — Continued Key Location by Thick- No. township and Alti- Description and correlation ness Depth on quarter section tude Feet Feet map 35 36 18 SW cor. NW 792 Key: 1, Recent and Pleistocene systems; 2, Pennsylvanian system — A, Carbondale formation, B, Pottsville formation; 3, Mississippian system — A, Burlington forma- tion. B. Hannibal formation, C, Sweetland Creek formation; 4, Devonian system. Cedar Valley and Wapsipinioon formations, (may include part of 5) ; 5, Silurian system, Niagaran series. d. Limestone, argillaceous. light bluish-gray, with some bands drab, buff, or brown Loess and drift , Shale, underclay, "slate,'' sand- stone and limestone , Limestone , 764 1 a. Loess and drift Gravel Drift Shale, black, hard, laminated... Coal (Rock Island No. 1) Shale Limestone Limestone, porous ("sand") 1. 2B, 3C 4. 1 a. b. c. 2Ba. b. 2B, 3C 4 a. b. 110 545 160 160 150 310 160 470 60 60 2 62 88 150 14 164 3% 167% 165% 333 140 473 2 475 T. 14 N., R. 2 W. (Greene Twp.) 37 4 SW SE NE 38 6 SE SW 69: 693 8 SW NW 700 1, 2, 3C? 4 a. b. 1. 2Ba. c. 4. 1. 2Ba. b. c. d. e. f. g. h. i. J. k. 4 a. b. c. d. e. f. Surficial clay and sand (1) ; coal, sandstone, limestone, shale, etc. (2) Limestone Sandstone (dolomite?) Loess and drift "Rock" (shale, sandstone, etc.).. Coal (Rock Island No. 1) Sandstone ; "soapstone'' (soft shale), and "slate" (hard, lam- inated shale), black (may in- clude part of 3C) Limestone Clay Shale, gray and dark Coal Shale, black Shale, dark Shale, light gray Shale, dark Coal Shale, gray, hard Coal Shale, dark Shale, gray, soft Limestone, brown Shale, gray, hard Limestone, dark Limestone, shaly, gray Shale, gray, hard Limestone, gray, with shale part- ings Limestone, gray 160 160 200 360 8 368 28 28 47 75 3 78 159 237 130 367 12 12 92 104 lVe 105% % 105% 2% 108 4 112 22 134 % 134% 24% 159% 2% 162 38 200 27 227 1 228 13 241 3 244 13 257 5 262 8 270 32 302 APPENDIX C 205 F.\nM Wells- -Continued Key No. on map Location by township and quarter section Alti- tude Description and correlation Thick- ness Feet Depth Feet 40 41 27 SE SE 28 NW SW 752 749 2B, 3C. 4. 1, 2, 2Ba. 2B, 3C. 4. Surface material "Slate" (hard, laminated shale), shale, underclay, etc Limestone No record Coal No record , Limestone T. 15 N., R. 3 W. (Perryton Twp.) 42d 33 NE SW 723 d Log of County Home well T. 14 N. R. 3 W. (Mercer Twp.) 43 5 NE SE 673 44 3 2 SE cor. 761 45 15 SW SE 753 46 17 SW SE 731 24 NW NE NW 753 48 26 SW cor. NE 732 49 26 SW cor. 50 28 NW cor. 725 708 51 33 NE SE 641 52 34 NW NW 728 1. Loess and drift. ; driller's record. 2B, 3C. Shale 4. Limestone 2B, 3C? 4 a. b. 1, 2. 2Ba. b. c. 2B, 3C, 4. 1. 2B, 3C? 4. 1. 2B, 3C. 4. 1. 2B, 3C. 4. 1. 2B, 3C? 4. 1. 2B, 3C. 4. 1. 2B, 3C. 4 a. b. 5. 1, 2, 3. 4. 1. 2B, 3C. 4. Surface clay and drift "Solid soapstone'' (shale) Limestone Limestone, porous ("sand") No record Coal No record Ccal (Rock Island No. 1) with "slate" (black shale) roof No record Limestone Clay and sand "Soapstone'' (shale, etc. ) Limestone Surface material "Soapstone" (shale) Limestone Surface material Shale, underclay, etc Limestone Surface material "Soapstone" (shale) and a little sandstone Limestone Loess and drift Shale Limestone Soil, clay, and sand Shale, soapstone, etc. (no coal) . Limestone "Mud," blue (shale?) "Solid rock, very hard" (probably chert or limestone) Surface materials and shale Limestone Surface material Shale Limestone 4 4 260 300 117 417 130+ 130 + 37130-140? 170? 302 130 432 100 100 120 220 168 388 100 100 170 270 130 400 1 401 79 79 1 80 17 97 4 101 165 266 130 396 160 160 142 302 130 432 120 120 115 235 180 415 140 140 130 270 126 396 150 150 ISO 330 150 480 90 90 150 240 165 405 70 70 159 229 100-f- 329 25 354 5 359 200 200 130 330 101 101 159 260 100 360 206 APPEXDIX C Fakm Wells — Continued Key Location by Thick- Xo. township and Alti- Description and correlation ness Depth on quarter section tude Feet Feet map Key: 1. Recent and Pleistocene systems; 2, Pennsylvanian system — A, Carbondale formation. B. Pottsville formation; 3, Alississippian system — A, Burlington forma- tion. B, Hannibal formation, C, Sweetland Creek formation; 4, Devonian system, Cedar Valley and Wapsipinicon formations, (may include part of 5); 5, Silurian system, Xiagaran series. T 13 N., R. 4 W. (Abington Twp.) 53/ 24 615± 1 a. Soil (and drift?) 40 40 / Log of Seaton village well ; driller's record. Sand (and Limestone . drift?) 5 4 56- 5S 60 61 62 63 64 T. 13 N., R. 3 W. (Ohio Grove Twp.) 1 SW XE 6 9- 1 X AT SW 2 XE XE 3 SW XW 4 SE XE 5 XE XE 11 XW cor 11 SE SW 12 XE XE 16 SW XE 6s: 6S5 679 655 693 676 701 665 16 SW. cor. XW 652 1. 2B, 3C. 4. 1, I 3. 4. 1. 2B, 3C. 4. 1. 2B, 3C. 4. 1, 2, 3. 4. 1. 2B, 3C. :b, 3C. 4. 1. 2B, 3C. 4. 1. 2B, 3C. 4. 1. 2B, 3C. 4 a. b. 1. 2B, 3C. Loess and drift Shale Limestone Surface clay and sand, and shale Limestone Clay and sand "Soapstorie" (shale) ; cemented gravel ledge well down in soap- stone is interpreted as basal conglomerate of Pennsylvanian. Limestone Drift "Soapstone" (shale) with 1 foot of coal Limestone "Soapstone" | shale) Limestone Surface clay and sand Shale Limestone Surface clays, sands, etc "Strips of rock" (sandstone, shale, limestone) "Soapstone" (shale) Limestone Surface material "Soapstone, solid" (shale) Limestone Drift Shale Limestone Loess and drift Xo record, except 18 inches coal reported under limestone Limestone Rock, hard (limestone or cherty limestone; Silurian?) Surface clay and sand "Soapstone" (shale). brownish, (may be residual soil on lime- stone) Limestone Limestone, porous, or "sand''.... 83 123 121 244 120 120 120 240 13 5 375 220 220 40 260 60 60 130 190 150 — 340^ 60 60 100 160 210 370 209 209 100- 3094 160 160 120 280 120 400 ? 1 'i •> y 216? 160? 376 60 60 168 228 116 344 80 80 ISO 260 116 376 100 100 60 160 160 320 16 336 160 160 1 161 140 301 2 303 APPENDIX C 207 Farm Wells — Continued Key Location by Thick- No. township and Alti- Description and correlation ness Depth on quarter section tude Feet Feet map ; T. 13 N., R. 2 W. (Suez Twp.) 65 26 NW NW 730 T. 13 N., R. 1 W. (North Henderson Twp.) 66 31 NW cor. NE 725 Warren County T. 12 N., R. 2 W. (Spring Grove Twp.) 67 17 SW cor. SE 700- 68 17 SE SW 20 SW SE 700- 703 T. 12 N., R. 3 W. (Sumner Twp.) 70 10 SE SW 666 71 13 SW NW 72 13 NW SW 73 13 SE SE 74 15 NE SE go: 680 CO: 655 75 17 SE cor. 618 76 20 SE SE 626 77 28 NW SW 615 1. Surface material 140 140 2B. Coal 2 142 2B, 3C. "Soapstone" (shale) 83 225 4. Limestone (probably includes part of 3C), "rotten" at bottom 283 508 1. Loess and drift 100 100 2B, 3C. Shale, "slate,'' and strips of rock and "fireclay" 250 350 4 a. Limestone 140 490 b. "Sand," (porous limestone) 18 508 1. Clay, blue 70 70 2B, 3B, 3C. Shale 210 280 4. "Rock'' (limestone) brown, red, yellow, and other colors... 166 446 1 a. Clay, red , 30 30 b. Clay, blue 40 70 2B, 3B, 3C. "Soapstone" (shale) 230 300 4. "Sandrock" (limestone), white... 100 400 1. Surface materials 100 100 2B?3C. "Soapstone" (shale) 120 220 4. Limestone (may include part of 3C) 212 432 1. Loess and drift 50 50 3C. "Soapstone (shale) 140 190 4. Limestone 175 365 1. Surface claj-s and sands 115 115 3B, 3C. "Soapstone (shale) 185 300 4. Limestone 135 435 1, 3. Surface clays with black "slate" (shale) (3C) 225 225 3C. Shale, gray 100 325 4. Limestone 135 460 1. Dirt and clay, red and blue 90 90 3B, 3C. "Soapstone" (shale) 200 200 4. "Rock'' (limestone) light colored 128 418 1. Surface material 100 100 3C. "Soapstone" (shale) 120 220 4. Limestone 120 340 1. Surface materials 145 145 3C. Shale, black, soft 55 200 4. Limestone ■ 150 350 1. Clay and sand 100 100 3C. Shale 100 200 4. Limestone 140 340 1. Loess and drift 65± 65h 3,4. Limestone 20± 85 ± "Soapstone" (shale) ? ? Limestone, blue ? 450 208 APPENDIX C Farm Wells — Concluded Key Location by Thick- No. township and Alti- Description and correlation ness Depth on quarter section tude Feet Feet map Key: 1, Recent and Pleistocene systems; 2, Pennsylvanian system — A, Carbondale formation, B, Pottsvihe formation; 3, Mississippian system — A : Burlington forma- tion, B, Hannibal formation, C, Sweetland Creek formation; 4, Devonian system, Cedar Valley and Wapsipinicon formations, (may include part of 5); 5, Silurian system, Niagaran series. 78 30 SE SE 675± 1. Loam and clay 70 70 3C. "Soapstone" (shale) 131 201 4 a. Limestone 170 371 b. Sandstone (porous limestone) (Niagaran?) 4 375 79 30 SE SE 675± 1. Soil and clay, yellow 65 65 3B, 3C. "Soapstone" (shale) 167 232 4. Limestone 140 372 SO 81 82 83 84 T. 11 N., R. 3 W. (Hale Twp.) 14 Cen. SE 745- T. 11 N., R. 2 W. (Monmouth Twp.) 12 SW SE 748- 29 NE NE 30 NE NE '50- 760; T. 11 N., R. 1 W. (Coldbrook Twp.) 20 NW NW '65- 1. 3A. 3B, 3C. 1 a. b. c. 3A. 3B, 3C. 4. 1 a. b. 3Aa. b. 3B. 1. 3Aa. b. c. 3B. 1 a. b. 3Aa. b. 3B, 3C. 4 a. b. Soil and clay Limestone "Soapstone" (shale) Loam, black Clay, yellow Clay, blue, with sand and gravel. Limestone, white "Soapstone'' (shale) "Sandstone, containing some lime" (limestone, porous and dolomitic) Loam and clay, yellow Clay, blue Limestone, blue Limestone, white "Soapstone" (shale) Dirt and clay Limestone, blue "Sandstone'' (cherty limestone). Limestone, white "Soapstone" (shale) 'bastard" (probably Clay, red . Clay, blue Limestone, cherty) Limestone, white "Scapstone'' (shale) "Sandrock" (limestone), white. Limestone, various colors 40 15; 260 4 36 80 30 250 150 60 30 70 40 5 110 60 10 30 40 30 50 30 90 200 70 45 40 55 315 4 40 120 150 400 550 60 90 160 200 205 110 170 180 210 250 30 80 110 200 400 470 515 Shallow Wells and Wells with Incomplete Records Mercer County T. 15 N., R. 1 W. (Richland Grove Twp.) !5 32 SW SE 730 1. Loess and drift 2Ba. Sandstone b. "Blue rock" (shaly sandstone at base. limestone) ; 80 80 20 100 3 103 APPENDIX C 209 Shallow Wells j^nd Wells with Incomplete Records — Continued Key Location by Thick- No. township and Alti- Description and correlation ness Depth on quarter section tude Feet Feet map T. 14 N., R. 1 W. (Rivoli Twp.) 86 5 NE SE 780 + 1. 2Ba. b c. d e. 87 7 NW SW 783 88 7 NW SW 783 89 7 SE NE 780 + 1. 2Ba. b. 90 16 NE SW 780 + 91 17 SW NW 786 92 17 SW NW 760 + 93 21 NE NW 783 94 30 761 1 a. b c. d 95 31 NW SW 745 + 1. 96 31 NW SW 745 + 1. 97 31 NW SW 745 + 98 32 SW NE T. 15 N., R. 2 W. 770± (Preemption Twp.) 99 32 NE SW 636 1. 100 34 NW SW 685 1. 2B. 101 35 SE SW T. 14 N., R. 2 W. (Greene Twp.) 666 1. 2B. 102 1 SE NW 742 103 4 SW NE 690± 1. 2Ba. b. 104 5 SW NE 680 + 105 6 SE SE 720 + 106 6 SW SW 680 + 107 8 SW NW 764 1. 2Ba. b. Glacial drift 60 60 Sandstone 30 90 "Blue rock'' (shaly limestone)... 8 98 "Cap-rock" (limestone) 2 100 Coal (Rock Island No. 1) iy 2 101% Shale, black 101% Reported to end in sandstone (may be sand in drift) 35 Water from limestone ; also water from sand at 130 feet 402 Glacial drift 120 120 Shale 2 122 Sandstone 18 140 No record. Coal present but thin ; water from limestone 480 No record. Coal, one foot re- ported ; water from limestone... 467 No record. Water from limestone 404 No record. Coal, one foot re- ported ; water from limestone... 486 Loam, and clay, yellow 25 25 Clay, blue 55 80 "Sea mud" ; clay, silt, and fine sand, white 70 150 Gravel 150 Clay, yellowish 108 108 Clay, yellow; no water 160 160 Water from gravel pocket 58 Water from gravel pocket 110 Alluvium (dug well) 10 10 Surface material 58 58 "Blue rock*' (shaly limestone)... 6 64 Clay and sand 17 17 Sandstone y 2 17y 2 No record. Reported to pass through coal (Rock Island No. 1) 125 No record to coal 18 18 Coal (Rock Island No. 1) 3% 2iy 2 "Fireclay" .(thin sandstone) 3y 2 25 Ends in sandstone 40 Coal, poor, sulfurous, 1-2 feet thick, reported at less than 100 feet; water from limestone 380 No record. Coal 1 foot 2 inches thick, reported at about 10 feet. 27 Surface material 14 14 No record 46 60 Coal (Rock Island No. 1) ? 60 + 210 APPENDIX C Shallow Wells and Wells with Incomplete Records — Continued Key- Location by Thick- No. township and Alti- Description and correlation ness Depth on quarter section tude Feet Feet map Key: 1, Recent and Pleistocene systems; 2, Pennsylvanian system — A, Carbondale formation, B, Pottsville formation; 3, Mississippian system — A, Burlington forma- tion, B, Hannibal formation, C, Cedar Valley and Wapsipinicon system, Niagaran series. 108 109 122 123 124 125 9 NW SW 11 SW NE 110 18 SE NW 111 21 SW SW 112 22 NE NE 113 23 NW SW 114 23 SW NE 115 25 NW NE 116 25 NE NW 117 26 SW SW 118 27 NW SE 119 27 NE SW 120 27 SW NE 121 29 NE NE 31 NW SE 31 NW SE 31 NE SE 34 SE NE 126 35 SE SW 127 36 SE NE 128 36 NE SW 780- 758 770; 760- 777 780 + 765 + 740± 745± 762± 762± 760± 757 700 + 705- 705 716 730± 740 + 725- 2Ba. 1. 2B. 1. 1. 2Aa. b. Ba. 1. 2B. 1. 2Ba. b. c. 1. 2Ba. b. c. 1. 2Ba. b. c. 1 a. Sweetland Creek formation; 4, Devonian system, formations, (may include part of 5); 5, Silurian No record. Ends a little below top of St. Peter sandstone No record , , Limestone ("Blue rock" and "cap- rock'') Coal (Rock Island No. 1) No record No rock ( dug well ) Surface material "Rock"' Loess and drift; petrified (?) logs reported; ends in gravel Surface material Shale, black Coal (Colchester) Rock, mostly shale ; limestone ("cap-rock") at base Coal (Rock Island No. 1) No record Surface material Shale, gray Water from gravel pocket in drift. Water from hard blue clay (Potts- ville shale) Probably no rock No rock No rock No rock i . Surface material ..' No record Coal (Rock Island No. 1) No record No record. Ends in Galena- Platteville (oil test ) No record "Blue rock'' (limestone and chert) Coal (Rock Island No. 1 ) Sandstone ? ; water from just below coal Passed through Rock Island (No. 1) coal and bed below it Surface material Sandstone Limestone, blue ("cap-rock") .... Coal (Rock Island No. 1 ) Base of well in sandstone Coal, one foot, at 135 feet; no cap- rock ; ends in sandstone Clay, blue Sand 1230 93 93 7 100 ? ? 45 145 + 40 140 140 40 180 50 30 30 9 + 39-4- 2i/ 2 4iy 2 ± 95± 136V2 3% 140 80 220 26 26 26 23 9 20 40 55 52 65 65 45 110 4 114 11 125 806 40 40 «? *? 70 407 70 70 18 88 2 90 4 94 150 150 100 100 25 125 APPENDIX C 211 Shallow Wells and Wells with Incomplete Records — Continued Key No. on map Location by- township and quarter section Alti- tude Description and correlation Thick- ness Feet Depth Feet 138 139 140 147 T 15 N., R. 3 W. (Perryton Twp.) 129 33 SW SW 680 + 1. 2Ba b 130 33 NW SE 725± 131 34 NE SE 705± 1. 2Ba b 132 35 SW SW 697± 133 35 SE SE 690± 1. 2B. 134 36 SE NW 725± 235 36 SW SW 700- 1. 2B. 136 36 SW SW 675-f- 2B. T 14 N, R. 3 W. (Mercer Twp.) 1 SE SE NW NE NW SW 141 3 SW SE 142 4 SW NE 143 8 SE SE 144 9 SE SW 145 9 SW SE 146 14 SE SE 647 710; 699 622 700- 700 : 720- 715± 759 14 NE SE 1. 2Ba. b. 1. 1. 2Ba. b. c. 1. 1 & 2. 2Ba. b. 1. 2B. !Ba. b. c. d. 767 1. 2Ba. 148 21 SW SE 721 149 24 SE SE 740+ 1. 2B 94 110 110 33 44 52 52 30 70 100 80 25; 30 10 u Surface material and glacial drift 94 "Soapstone" (shale) 16 Sandstone at base Dug well ending in sand, no rock. Glacial drift 44 "Soapstone" (shale) 8 Sandstone No rock Loess and glacial drift 70 Sandstone 30 No record. Penetrates rock (Pottsville) Drift ■". 25 Sandstone 5 Sandstone at top and base No record. Passed through sand- stone (Carbondale?) and coal; filled in with rock 50 feet on • account of quicksand Surface material 8 Coal (Rock Island No. 1) Sandstone, shaly 5% 14 Sand and clay (dug well) 60 60 Glacial drift 16 16 Sandstone 15 31 "Slate" (shaly limestone), blue.. 4% 35 1 / j> Coal (Rock Island No. 1) 2% 38 Alluvium and drift Surface material and a little rock 50 Coal No record 4 No record Surficial material and glacial drift 34 Sandstone 2 No record Loess and glacial drift SO "Soapstone" (shale) 15 "Cap-rock and Blue rock" (lime- stone and shaly limestone) ? Coal (Rock Island No. 1) 4 Sandstone ? Loess and giacial drift 90 "Soapstone" (shale), "Blue rock" (shaly limestone), and "cap- rock" (limestone) 22 Coal (Rock Island No. 1) 5 No record. Well ends in Galena- Platteville limestone 795 No record. Poor supply of water. Surface material •. 50 Sandstone 18 30 50 50% 55 40 34 36 40 80 95 136 90 112 117 912 266 50 68 212 APPENDIX C Shallow Wells ahd Y\"ells with Ixcomflete Records — Continued Key Location by Thick- No. township and Alti- Description and correlation ness Depth on quarter section tude Feet J Feet map Key: 1. Recent and Pleistocene systems: 2. Pennsylvanian system — A, Carbondale formation. B. Pottsville formation: 3, Mississippian system — A, Burlington forma- tion, B. Hannibal formation, C, Cedar Valley and Wapsipinioon system, Niagaran series. Sweetland Creek formation; 4, Devonian system, formations, (may include part of 5): Silurian 150 151 15: 25 SW 26 SW 2 7 XE XE 153 2 7 NW NW 710- 154 2S XE X'E 725 — 155 32 XE XE 720- 15 6 34 NW XE 725 — 157 & 15S 36 NW NW 705± T. 13 N.. R. 3 W. (Ohio Grove Twp.) 159 1 X'W X" w 685+ 160 9 SW SE B80- 161 162 163 164 165 166 167 16S 169 SE XW SW X"E NW NW 679 690 1. 2. 16 SW X'E SE XE X'W NW 16 SW SE XE XE !1 XE NW 174 175 176 177 178 17:' L80 SE XTT NW SW NW SE xw xw 3 3 SW SW 3 4 34 SE XE 36 SB SW 36 XI ". SB T. 13 N.. R. 2 W. (Suez Twp.) 2 SE SE 6 •:• a — 1. 2. 3 654 670± 1 a. b. 641 1. 2 7, 672 = 1 a. b. 635± 631 640- 1 a. b. 640— 620 + 1. 3C. 1. 600 + 1. 1. 620 + 1. 640 1. 640 1. 2 or 3 750± 1. 2B& : Xo rock Soil and clay 135 C ? Shale 50 Limestone, fossiliferous, pyritic. 95 Xo record. Water probably from limestone No record Xo rock Xo rock. Water from gravel pocket in drift Xo record. Xo coal reported No records. Two wells, similar depths Xo record. Water from limestone Loam and clay 60 Sand 2S Xo record. Water from limestone X"o record. Water from limestone . & 4. Surface clay and sand, "soap- stone" (shale), and limestone . & 4. Surface clay and sand, "soap- scone" (shale), and limestone Xo record. Water from limestone Loess and clay 60 Sand 37 3. & 4. Surface clay and sand, ■'soap- stone'" (shale), and limestone Loam and clay 74 Sand Xo rock. Water from sand in drift No record. Water from limestone Loam and clay 64 Sand ? Xo record. Probably no rock Loess and drift 65 "Soapstone" (shale) 15 Loam and clay; sand at base Loam and clay; water in gravel.. Loam and clay: water from sand. Loess and drift; water from sand. Loess and drift: water from sand. Surface material 100 "Soapstone" (shale); no water.. 60 Drift 60 5C. "Soapstone" (shale) 90 60 135 1S5 2S0 425 375 70 30 390 490 400 60 ss 336 343 372 314 425 60 2S6 74 74 40 300 64 64 + 106 65 SO 91 SO 116 SO SS 100 160 60 150 APPENDIX C 213 Shallow Wells and Wells with Incomplete Records — Continued Key Location by Thick- No. township and Alti- Description and correlation ness Depth on quarter section tude Feet Feet map 1S1 8 NW NW 182 8 NW NE 183 10 SE SW 184 10 SE SE 185 10 SE SE 186 11 SW NW 187 15 SE NE 188 15 SE SW 189 16 SW SW 190 17 SE NE 191 17 SE SE 192 17 SE SW 193 17 SW SW L94 18 SE NP1 195 & 196 18 SE SW 197 20 NW NW 198 20 SE SW 199 20 SE SE 200 21 SW SE 201 21 SW NE 202 22 SE NW 203 25 NW SW 204 28 205 29 SE NW 206 30 NE NE 207 31 208 31 209 31 NE NW 210 31 SW SW 700+ 1. Drift 85 85 2B. Limestone l 86 No record 115 Drift 100 100 , & 4. ?. Mostly sandstone 235 335 Loess and drift 60 60 Rock, mostly sandstone 60 120 Glacial drift 85 85 Sandstone 5 90 Glacial drift and sand ; water from sand 80 80 Clay, blue 140 140 Sand and gravel at base 140 Surface material 60 60 "Soapstone" (shale) 30 90 No record. Flowing 1 well 60 Mainly in sand, water rises to 9 feet from top 95 No record. Flowing well 60 ? No record. Flowing well, water probably from sandstone beneath shale 100 No record. Water probably from sandstone beneath shale 100 No record. Flowing well 85 No records. Two flowing wells... 60 + Water in sandstone below shale ; top of sandstone at 100 feet.... 109 Surface material 50 50 Shale; no water 50 100 Loess and glacial drift 20 20 Sandstone 16 36 Clay, yellow 20 20 Clay, blue 40 60 3C? "Soapstone" (shale) 80 140 Surface material 25 25 Sandstone 5 30 Loess and glacial drift 60 60 Shale 28 88 Sandstone 2 90 Sandstone, with two thin beds of coal under drift, ends in shale.. 116*4 Loam and clay; water from sand. 89 89 Loam and clay 4 5 45 Sandstone, red and yellow, soft 47 92 Loess and glacial drift 60 60 Sand 10 70 Loam and clay; water in sand... 110 110 Loam and clay: water in sand... 102 102 No record. Water from sandstone at base 14 5 Loess and glacial drift 74 + 74 + Sand and clay in alternate layers ; water from fine sand 40+ 114 705 + 725± 1. 2B, 3 728 + 1. 2B. 730 + 1. 2B. 730± 1. 720 + 1 a. b. 705 + 1 a. 2B. 670 + 680 + 1. 680 + 680± 680± 650± 640 + 663± 700 + 1. 2B. 705 + 1. 2B. 680 + 1 a. b. 2B& 705± 1. 2B. 700 + 1. 2Ba. b. 710 + 1. 695 + 1. 2B. 700 + 1 a. b. 1. 1. 665 + 645 1 a. b. 214 APPENDIX C Shallow Wells and Wells with Incomplete Records — Continued Key Location by Thick- No. township and Alti- Description and correlation ness Depth on quarter section tude Feet Feet map * Key: 1, Recent and Pleistocene systems; 2, Pennsylvanian system — A, Carbondale formation, B, Pottsville formation; 3, Mississippian system — A, Burlington forma- tion, B, Hannibal formation, C, Sweetland Creek formation; 4, Devonian system, Cedar Valley and Wapsipinicon formations, (may include part of 5) ; 5, Silurian system, Niagaran series. 1. Clay and glacial drift, sand at base „ 1. Glacial drift 2B or 3C. "Soapstone'' (shale) Well in sand, no rock 1. Loess and glacial drift and much sand 2B or 3C. Shale 1 a. Loam and clay, yellow b. Clay, blue 2Ba. Shale and sandstone b. Limestone, gray 211 31 NE NE 670 212 32 SE SE 667 213 32 SW SE 650 214 33 SW NW 680 215 35 SE SW 685 T. 13 N., R. 1 W. (North Henderson Twp.) 216 6 NE SE 778 760 + 760 + 780 + 760 + 745± 742± 740 + 740± 750± 760 + 730 + 730± 720 + 217 6 SE SW 218 7 NE NE 219 9 NW NW 220 9 SW NW 221 9 SW SE 222 17 SE SE 223 19 SE SE 224 20 SW SW 225 20 SW SW 226 20 SW SE 227 29 SW SE 228 30 SW NW 229 30 SW SW 1. Surface material 2 A. "Slate" (shale) and coal.. 2B & 3C. "Soapstone" (shale) 1. Glacial drift 2B. Sandstone 1. Loess and glacial drift... 2B. Sandstone 1. Loess and glacial drift.... 2B. Sandstone 1. Loess and glacial drift... 2B. Rock, probably sandstone. Water from loose sand . . . 1. Loess and glacial drift... 2B. Sandstone No record 1. Loess and glacial drift.... 2B. Rock 1. Glacial drift 2B. Sandstone 1. Glacial drift 2B. Sandstone 1. Loess and glacial drift... 2B. Sandstone No record 1 a. Loam and clay 2B. Sandstone 100 40 40 40 180 115 115 115 35 35 60 95 24 119 26 145 60 60 1 61 219 280 106 106 4 110 123 123 5 128 79 79 5 84 60 60 1 61 85 103 103 10 113 175 120 120 120 127 127 15 142 135 135 15 150 125 125 5 130 149 *> ? 7 119 230 231 Warren County T. 12 N., R. 1 W. (Kelly Twp.) 4 SW SW 5 NE NE 705 700 + 1. 2B? 1 a. b. 2B? Surface material Limestone? Loam and clay . . Clay, blue Limestone 110 110 5 115 30 30 40 70 2 72 APPENDIX C 215 Shallow Wells and Wells with Incomplete Records — Continued Key Location by Thick- No. township and Alti- Description and correlation ness Depth on quarter section tude Feet Feet map 232 5 NE NW 233 7 NW SW 234 16 235 16 NW NE 236 16 SE SE 237 17 NE SW 700+ 1 a. b. 2B. 705 700 ± 1 a. b. c. d. 715 Loam and clay, yellow Clay, blue Sandstone No record. Bed of coal 2 feet thick reported No record. Ends in rock, proba- bly Pottsville sandstone No record. Water from sandstone Loam and clay, yellow Clay, blue Sand and clay mixed Sand, clean Surface material 2Ba or 2A. Rock 238 20 SE SW 239 30 SE NW 705 750- 2Bb. c. d. e. f. g. h. 1 & 2B. 2Ba. b. c. Coal Sandstone No record Limestone Coal (Rock Island No. 1 ) Underclay Sandstone Surface material and rock above limestone Limestone and "slate'' (shale)... Coal (Rock Island No. 1 ) Sandstone No record. Penetrates No. 2 coal at 30 feet and a coal bed 4 feet thick (probably Rock Island No. 1) at about 95 feet T. 12 N., R. 2 W. (Spring Grove Twp.) 240 1 NE NE 241 6 NW NW 242 8 SE SE 243 8 SE SE 660 + 244 9 SE SE 685± 245 9 SE NE 660 + 246 11 NW NW 660 + 247 11 NW NE 660 + 248 704 1. Loess and glacial drift 2B. Sandstone 616± 1 a. Loam and clay, yellow ' b. Clay, blue c. Sand 670± 1. Surface clay and sand 2Ba. "Soapstone" (shale), sandy b. Sandstone 1. Surface clay, sand, and gravel . . . 1 a. Dirt and clay b. Sand and gravel 2B & 3C. "Soapstone" (shale) 1. Clay 2B&3C? Shale and sandstone Water in sand, white; no rock... 1 . Loess, drift, and gravel 2Ba. "Shelly rock'' (shale) 2Bbor3B. Clay (shale), white ?. Rock 11 SE SW 680+ 1. Surface clay, sand, and gravel black sticky muck 28 28 39 67 18 85 145 30 30 60 90 48 138 12 150 14 14 66 80 1 81 •j 81 + 13? 94 12 106 4 110 Vz 110% 9% 120 f 9 ? 139 2 141 191 100 60 60 20 80 30 30 40 70 28 98 97 97 1 98 98 113 113 35 35 40 75 135 210 80 80 50 130 87 72 72 73 145 25 170 170 160 160 216 APPENDIX C Shallow Wells and Wells with Incomplete Records — Continued Key Location by- Thick- No. township and Alti- Description and correlation ness Depth on quarter section tude Feet Feet map Key: 1, Recent and Pleistocene systems; 2, Pennsylvanian system — A, Carbondale formation, B, Pottsville formation; 3, Mississippian system — A, Burlington forma- tion, B, Hannibal formation, C, Sweetland Creek formation; 4, Devonian system. Cedar Valley and Wapsipinicon formations, (may include part of 5); 5, Silurian system, Niagaran series. 249 12 SW SE 700+ No record. Bed of coal (Rock Island No. 1) 3 feet thick re- ported 90 i '!;-,!■ Clay, sand, and gravel; ends in sand Loam and clay, yellow Clay, blue Sand Gravel 252 18 SW SW 685 1. Surface materia! 2B, 3B, or 3C. "Soapstone" (shale) 253 21 Cen. SW 715 1 a. Loam and clay b. Sand c. Clay, blue ' 2B, 3B, 3C. "Soapstone" (shale) 254 255 256 257 262 263 264 265 266 267 2 SW SE 700 + 4 SE NW 670± 1. 4 NW NW 8 SW SW 680+ 1 a. b. c. d. 685 1. 21 NE SE 22 NW NW 23 SW NE 24 SE NE 725 700- 690- 717 3Ca. b 1. 2B "Rock" (limy shale) "Soapstone" (shale) No record. Coal iy 2 feet thick at 35 feet; water from sandstone below coal Soil and clay Limestone, impure, and "soap- stone" (shale), (may include 3A or 3B) Water from brown gravel and sand, shale at base 1, 2A?, 2B. Surface material and rock 129 129 30 30 60 90 30 120 1 121 20 20 20 30 30 3 33 17 50 120 170 10 180 1 181 55 50 50 90 258 24 SW SW 731 £59 25 NW SW 740 260 26 SE NE 740 261 29 SE NE 710 2Ba. 1 a. 2B. "Cap-rock'' and "slate" (lime- stone, shaly limestone, and laminated shale) Coal (Rock Island No. 1) No record. Ends, in sand Loam and clay Clay, blue Sandstone No record. Ends in sandstone.... No record. Reported shale and coal and natural gas T. 12' N., R. 3 W. (Sumner Twp.) 1 NW NW 2 NW NW 3 NE NE 4 NW NW 5 NE NE 11 NW SW 640+ 1 635± 635± 605± 600 + 690 1. 1. 1 a. b. 1. 1. Loam and clay, yellow Clay, blue Sand Loam and clay, water from sand. Loam and clay, water from sand. Loam, sand, and clay, alternating Sand Loam, clay, and sand Loess and glacial drift ; logs in or below drift 140 63 63 63 12 75 4 79 110 30 30 41 71 12 83 120 6 7 30 30 40 70 15 85 62% 62 76 76 82 82 3 85 97 97 10 10 APPENDIX C 217 Shallow Wells and Wells with Incomplete Records — Concluded Key No. on map Location by township and quarter section Alti- tude Description and correlation Thick- ness Feet Depth Feet 268 31 NW SE 705 + 1. 269 11 SW SE 690 + 1. 270 12 SW SW 702 + 1 a. b. c. 3B? 271 12 SE SE 700 1 a. 3B& 3C. 272 15 SE SE 640 1. 3B, 3C. 27 3 15 SW SE 640 + 1. 3B, 3C. 4. 274 16 NE SE 620 + 1. 275 16 NW NW 620 + 1. 276 20 SE SE 620± 1 a. b. 277 20 SE SE 620± 1 a. b. c. 278 20 SE SE 620 + 1. 279 20 SE SE 620± 1 a. b. 280 20 SE SE 620 + 1. 281 20 SE SE 620 + 1. 282 20 SE SE 620 + 1 a. b. 283 21 SW SW 620± 1 a. b. 284 21 SW SW 620± 1 a. b. 285 21 SW SW 620 + 1 a. b. 286 21 SW SW 620± 1 a. b. 287 21 NW NW 620 + 1. 288 22 NW NE 652 289 23 NW NW 655 + 1. 3B, SC. b. 290 24 SW SW 655± 1 a. b. c. d. e. 3Bor 3C 291 24 SW SE 650± 1 a. b. c. 3B or 3C 292 24 SE SE 625± 293 25 NE NW 655 + 1. 3B or 3C 294 27 NW SW 640 + 1. Loam and clay; water from sand 74% 74% Loam and clay; water from sand 73 73 Surface clay 15 Gravel 3 Sand and loam, sandy 177 Clay, blue Surface clay 15 "Soapstone" (shale) 170 Surface material 4 "Soapstone'' (shale) 50 Loess and glacial drift 60 Shale ? Limestone ? 343 Loam and clay; water from sand. 55% 55% Loam and clay ; water from sand ; no rock 88 88 Loam and clay Sand Soil and clay, yellow Clay, blue, with pockets of sand. Sand Loam and clay ; water in sand .... Soil, yellow, and clay, blue Sand Loam and clay ; water in gravel . . Loam and clay ; water in sand Loam and clay Sand and gravel Loam and clay Sand Loam and clay Sand Loam and clay Sand and gravel Loam and clay Sand Loam and clay ; water in sand .... No record. Water from limestone Surface material "Soapstone" (shale) Sandstone Claj', red, peat at bottom Clay, blue ." Sand Clay, blue Sand "Soapstone" (shale) Clay, red Clay, blue Sand "Soapstone" (shale) No record. Water reported in gravel Surface material ? "Soapstone" (shale), blue Loam and clay; water in sand.... 104 126 6 40 77 15 78 73 % 8 87 75. 98 6 65 4 51 5 55 5 65 84 30 40 18 52 4 56 7 20 96 8 15 18 195 195 15 185 40 90 60 126 132 40 117 132 78 73% 81% 87 75 98 104 65 69 51 56 55 60 65 72 84 373 30 70 70 18 70 74 130 137 137 20 116 124 124 125 ? 118 104 INDEX A Page Abingdon Township, log of Seaton village well 206 Aftonian epoch, history 126 Af tonian series 30 Agriculture 26, 151 Alden Coal Co. mine Nos. 1, 2, 3, 4, mine data 175-176 Alden Coal Co. well, penetrating St. Peter formation 155 Aledo 137 City well No. 2, gastropods from well samples 96 City wells Nos. 1, 2, logs 190,192 City wells, penetrating St. Peter formation 155 New Richmond formation at 33 Population of 26 St. Peter formation, elevation of base 109 Sandstone quarried near 147 Transportation 27 Water supplies 149 Well, penetrating Cambrian strata 29 Alexander County Devonian strata, outcrops 39 Alexandrian series 38 History 119 Alexis City well, log 195 City well, penetrating St. Peter formation 155 Population 26 Water supplies 149 Alexis quadrangle Area of 15 Geologic formations in 30 Allegheny formation 47 Alluvial deposits, soil formed from. 151, 152 Alluvial fans 106, 131 Alluvial flats 131 Alluvial valleys, width of 106 Alpha 108, 138 C. B. & Q. Railroad well, log 188 Amphibolite in Kansan and Illinoian tills 99 Analyses Clay for brick 141 Clay for flue-tile 143 Rock Island coal 135 Water (Table 3) 148 Analysis, sieve Pre-Illinoian (Yarmouth) sand 146 Andalusia, village of 63 Appalachian highland 116 Appalachian province 47 Argillo Works Well, log 185 Page Arkansas, "Chattanooga" shale corre- lated with Sweetland Creek 43 Arkose in Kansan and Illinoian tills 99 Avon quadrangle 14, 75 "Bad-land" topography 24,25,131 Bailey mine, mine data 175 Baker, F. C, assistance of 16 Basalt in Kansan and Illinoian tills. 99 Beekmantown series 33 Pernadotte, Illinois 76 Bernadotte sandstone 76 Black Diamond Coal Co. Mine data 173 Rock Island coal in 135 Suite n, measured section No. 17. 168 Black River formation, correlated with Decorah 37 "Black Slate" 41 Bloomington moraine, mantled with loesslike silt 106 "Blue rock" Burned for lime 147 Fossils (tabulated) 157-163 History 122 Quarries - 147 "Blue sand" 120 Bonick mine Mine data 174 Suite II, measured section No. 15. 167 Brick manufacture 143 Clays for 141 Glacial drift for 142 Loess for 142 Shale for 141 Buda, Illinois 63 Building stone 146-147 Sandstone 147 Limestone 147 Quarries 147 Burgess, town of 26 Water supplies 150 Yarmouth sands near 98 Buried valleys, pre-Pennsylvanian. .46-47 Burlington formation Classified 30 Described 45-46 Economic uses 147 Escarpment 121, 127 Fragments in Illinoian drift 98 Fragments in Pennsylvanian con- glomerate 44, 47 History 120 Outcrop 44, 46 Pre-Pennsylvanian highland 47 219 220 INDEX— Continued Page Cady, G. H., assistance of 15 Calhoun County, Devonian strata, outcrops 39 Cambrian system Described 29-31 History 116 Water-bearing" formations 148 Canada 98 Canton quadrangle 14 "Cap-rock" 61 Fossils (tabulated) 157-163 Roof in mines 137 Carbon Cliff, Argillo Works well, log 185 Carbondale formation Classification 30 Colchester coal (See Coal, Col- chester) Defined 78 History 123-124 Origin of name 78 Strata in Alexis quadrangle 49 Suite IV Colchester coal 83 Concretions, fossiliferous 86 Correlation 89 Defined 51 Fossils (tabulated) 157-163 Geologic sections 15, 17, 19; Ap- pendix B 73, 75, 80; 171-173 Limestone, dark, fossiliferous... 86 Paleontology 89 Sandstone, basal SO Sequence 49,77,80 Shale, black, above coal 84 Shale, gray 87 Shale, gray, above coal 84 Shale, gray, with concretions.... 86 Stratigraphic relations 88 Underclay 83 Suite V Correlation 90 Described 89-91 Geologic section 20 90 Pleasantview sandstone. .49, 82, 90, 124 Stratigraphic relations 90 Carbondale, Illinois 7S Cayugan series 30, 38 Cedar Creek Soil on terrace remnants 152 Valley of preglacial stream 124 Water polluted 151 Cedar Valley formation Classified 30 Described 40 History 120 Underlying Pennsylvanian strata.. 46 Cenozoic group 29, 30 History 124 Ceramic materials 141-143 Ceramic plants Hydraulic Press Brick Co 142 Page Northwestern Clay Manufacturing Co 143 "Chattanooga" shale, correlated with Sweetland Creek 43 Chautauquan series 30 Chazy-Lowville series 36 Chazy series, correlated with St. Peter formation 33 Chemical analyses Coal, Rock Island (No. 1) 135 Water 148 Chert in Kansan and Illinoian tills.. 99 Chester series Classified 30 Described 41 Chicago, Burlington and Quincy R. R .27, 137, 143, 151 Wells, logs 188, 195 Chouteau formation Classified 30 Described 41 Cincinnatian series Classified 30 Described 37 History 119 Clays, mineral resources 141-142 Clay pits, Geologic sections 15, 16, 27 73, 74, 101 Clay, tested for use in flue-tile 143 Clinton, course of preglacial Missis- sippi • 124 Clinton subseries 30 "Clod" 58, 59, 137 Coal Colchester (No. 2) Altitudes determined 107 Altitudes in quadrangle 112-113 Associated strata, described 80-89 Carbondale formation 48, 49 Correlated with Murphysboro (No. 2) coal 48 Described S3 Distribution in quadrangle 140 Geologic sections 15, 17, 19; Ap- pendix B, Pt. II... 73, 75, 80; 171-173 Graphic representations 79, 81 History 123 Resources 133,140 Roof 140 Structure 112-113 Underclay 83 Danville (No. 7) 47 Distribution of workable beds 133 District III 133 Herrin (No. 6) 47, 78 Local Distribution 138, 140 Geologic sections 3, 4-6, 8, 10-11, 13-16, 20 51, 52, 53, 54, 65, 67, 6S, 72, 73, 74, 90 Outcrops along Pope Creek 51 Matherville 63, 133 Mining 26 INDEX— Continued 221 Page Murphysboro (No. 2) 47, 78 Test boring Altitudes estimated 107 Graphic log 69, 70 Logs 69,70,94 Rock Island (No. 1) Altitude in test-boring 139 Altitudes determined 107 Altitudes in quadrangle 112 Areas of mining 133 Areas mined out 134 Areas probably underlain by 137 Associated strata, described 55-64 Clay parting 58 Correlated with No. 1 coal of Fulton Co 63 Described 57-58 Floor 137 Geologic sections 4, 5, 7. 8, 10-12, 16; Appendix B, Pt. 1 52, 53, 56, 65, 67, 68, 69, 74; 164-171 Graphic representations 135 History 121 Mines in 1926 133 Origin of name 57 Pyrite concretions 58 Rank of 135 Resources 133-138 Roof 137 Structure Ill Thickness 57-58 Thickness mined 133 Underclay tested 141 Coals, uncertain stratigraphic posi- tion 140 Coal Valley Mining Co., mine data.. 176 Cobalt district 127 Colchester coal (see Coal, Colchester) Coimar oil field 153 Comanchean system 30 Concretions 59, 82, 86 Fossiliferous 60, 70, 80, 86 "Ironstone" 70 Ironstone, in Kansan and Illinoian tills 99 Septarian 86,88 Conemaugh formation 47 Conglomerate, basal Pennsylvanian.44, 77 Conglomerate, jasper 98,127 Cook farm, oil test on 154 Coral reefs, Devonian 120 Cordilleran center of glaciation 125 County Home well, log 205 Cretaceous period, erosion 124 Cretaceous system 30 "Crinoidal" limestone (see Burlington formation) Croixan series Classified 29,30 History 116 Cross-bedded sands, Yarmouth 96 Culver, H. E., assistance of 15 D Page Danville 39, 41 Danville (No. 7) coal 47 Decorah, city of 36 Decorah formation Classified 30 Described 36-38 Deforestation, effects of 24,25,131 Devonian system Classified 30 Described 39-41 History 119 Structure 109-110 Surface 47 Water-bearing 148, 150 Devonshire, England 39 Diastrophism 21 Dixon, Illinois, Lowell Park limestone 37 Dodgeville peneplain 124 Dolomite in Kansan and Illinoian tills 99 Drainage Alexis quadrangle 24-26 Artificial 131 Mines 141 Drain tiles 26, 143 Dresbach formation Classified 30 Described 30 Elevation at Moline and Monmouth 109 History 117 Structure 108-109 Water-bearing 148 Dresbach, Minnesota 30 Drift mining 140 "Driftless area" 124 Duck Creek valley 151 E Eastern Interior Basin 116 East Moline, city wells Nos. 1, 2, logs 179, 180 Eau Clair formation Classified 30 Described 30 History 117 Eau Clair, Wisconsin 30 Edgington quadrangle 14, 75 Edwards River Dammed by aggradation of Missis- sippi 130 Pottsville formation along tribu- taries to 50 Prelllinoian valley 124, 127 Soil on terrace remnants 152 "Stigmarian" sandstone along 57 "Stigmarian" sandstone along trib- utary 55 Ekblaw, G. E., assistance of 15 "Encrinital" limestone (see Burling- ton formation) 222 INDEX — Continued Page Engine sand 146 Eocene system 30 Eolian deposits 106 Erian series 30 F "False bottom" 133 Farm Creek, exposure of Sangamon deposits along 104 Farm wells 150 Logs 202-208 Faults 111,137 Fern Glen formation Classified 30 Described 45 Fernvale, correlated with Galena formation 38 Ferretto zone 102 Filter sand *. • • 146 "Fireclay" series 47 Flooding 131 Flowing wells 151 Flue linings 26 Flue-tile 143 Fossils (see also Paleobotany and Paleontology) Criteria in correlation 21 Pennsylvanian 158-163 Peorian 105 Francis Creek 89 Francis Creek shale 49 Restriction of name 89 Franklin Grove, Shakopee exposed near 11" Franconia formation (see Mazomanie- Franconia) Franconia, Minnesota 30 Fulton County Avon strata equivalent to part of Suite IIJ 76 Colchester coal thinner than in Alexis area 123 Parks Creek limestone, correlated with Suite II 64 "Spoon River" strata correlated with Suite 1 55 Type locality of Francis Creek shale 89 Type locality of No. 1 coal 63 Galena formation Classified 30 Described 37 History US Oil possibilities 153 Oil show reported from 154 Oil tests to be carried through.... 155 Structure 108-109 Water-bearing 148 Page Galesburg, city of 109, 151 Carbondale (Suite IV) exposed in.. 89 City well (Geiger No. 1) log 201 Galesburg quadrangle 14, 16 Gas (see Oil and gas) Geography 26 Gilchrist mine (New), mine data 176 Gilchrist mine (Old), mine data 175 Gilchrist, mining town 26 Transportation 27 Water supplies 150 Gilchrist shale Ceramic raw material 141, 143, 146 Classified 49 Described 73-74 History 122 Stratigraphic relations 83, 88, 142 Structure (overturned fold) 114 Geologic processes described 16-22 Gilmore and Houston mine, mine data 175 Glacial drift Ceramic raw material 142 Classification in Alexis quadrangle 30 Filling channels cut into Pennsyl- vanian strata 88 Gravel from 146 Ulinoian 98-103 Kansan 94-96 Water-bearing 149, 150 Glacial movement, direction of 98 Glaciation 19 History 125-130 Glauconite, in Mazomanie-Franconia formation 30, 117 Glenwood formation Classified 30,31 Described 34-36 History 118 Glenwood Township, Iowa, type lo- cality of . Glenwood formation 34 Gneiss in Kansan and Ulinoian tills. 99 Good Hope quadrangle 14 Goose Run Flowing wells in valley 151 Preglacial valley 126 Granite in Kansan and Illinoian tills 99 Grassy Creek shale 41, 42, 43 Gravel, distribution of 146 Graywacke in Kansan and Illinoian tills 99' Greene Township Preglacial surface, highest 91 Pottsville formation, outcrops 51 Rock Island coal, mined 138 Rock Island coal, structure Ill Green River, Devonian strata south of 39 Greenstone in Kansan and Illinoian tills 99 Griffin Brick plant at 26, 141, 143 Coal near 137 Grim, R. E., assistance of 15' INDEX — Continued 223 H Page Hannibal formation Classified 30 Described 43-45 History 120 In southwestern Illinois 41 Pre-Pennsylvanian lowland 47, 121 Valleys in 91 Water-bearing zone 148-149 Hannibal, Missouri 43 Hardin County, Devonian strata, out- crops 39 Helderbergian series 30 Henderson Creek Area of Rock Island coal 138 Dammed by aggradation of Missis- sippi 130 Deposits of pre-Illinoian sand along 146 Fossiliferous sandstone along 71 Pottsville formation near. 50 Preglacial valley 91 Soil on terrace remnants 152 Unconformable strata along 55 Yarmouth valley near 126 Hennepin, course of preglacial Mis- sissippi 124 Herrin (No. 6) coal Formerly correlated with Rock Island coal 63 Top of Carbondale formation 47,78 Henry County Alpha, coal mined at 138 Alpha well, log 188 Devonian strata, outcrops 39 Orion city well, log 186 Woodhull village wells, logs 186,187 Historical geology 115-131 Principles of interpretation 115 Hoing sand 153 Hopewell Coal near 137 Station, transportation for North- western Clay Mfg. Co 143 Hudson Bay, Niagaran sea from.... 119 Hydraulic Press Brick Co 26 Coal in test-boring near 139 Fault near pit 113 Fossil plants from pit 76 Gilchrist shale 141,142 Mine, mine data 174 Mine, measured section No. 5 (Suite II) 165 Pit, geologic section 15 73 Plant described 142-143 Rock Island coal near 75 Water supplies 150 I Ice-shove, deformation by 113,127 Illinoian glacial series Classified 30, 92 Count of pebbles from 99 Page Described 98, 108 Geologic sections 21-27 93,99-101 Gumbotil 104 History 127 Water-bearing beds 149,150 Illinois River Former course of Mississippi...... 124 St. Peter sandstone along 33 Industries 26 Interior glaciated plains province... 23 Iowa Kansan glacier 126 Type Sweetland Creek formation in 43 Iowa City, position of edge of Iowan glacier 128 Iowan glacial series Classified 30, 92 Described 104-106 History 128 Jackson County Devonian strata, outcrops 39 Type locality of Carbondale forma- tion 78 Jasper conglomerate 99, 127 Jersey County, Devonian strata, out- crops 39 Joachim formation, correlated with Glenwood 36 Joliet formation 30, 39 Jordan formation 30 History 117 Jordan, Minnesota 30 Jurassic system 30 Kansan glacial series Classified " 30 Count of pebbles from 99 Described 94-96 Geologic sections 21, 22 93 Gumbotil 95,96 History 126 Kansan glacier, direction of advance 126 Kansan (?) valley-train, water-bear- ing 150 Keewatin center of glaciation 125, 126, 128, 129 Kelly Township Burlington chert in glacial drift.. 98 Colchester coal, thickness 140 Kentucky, Chattanooga shale corre- lated with Sweetland Creek 43 Keokuk formation Absent in Alexis quadrangle 45 Classified 30, 45 History 120 Kinderhook, Illinois 41 224 INDEX— Continued Page Kinderhook series Below glacial drift 23 Classified SO Described 41-45 Oldest exposed rock 29 Outcrop 77 Kness Coal Co. Measured section Mo. 18 (Suite II) 168 Mine data 173 Knox County, Colchester coal thinner than in Alexis area 123 Labradorean center of glaciation .... 125, 127, 129, 130 La Harpe quadrangle 14 Laird, Will, oil-test on farm 154 Lake Huron 20, 98, 127 Lake Superior 20,116 Lancaster peneplain 124 La Salle 39,41 St. Peter sandstone near 33 La Salle anticline, uplift 121 Leaching, in soil formation 153 Lee County St. Peter sandstone in 33 Shakopee exposed near Franklin Grove 117 Lee mine, mine data 174 Leighton, M. M., assistance of 15 Lillaman mine, Rock Island coal in.. 135 Lime 147-148 Limestone Blue rock (Suite II) 62 Cap-rock (Suite II) 61 Dark, f ossiferous (Suite IV) 86 Quarries 147 Limestone in Kansan and Illinoian tills 99 Little Maquoketa River 37 Little Platte River 36 Little York 26 Transportation 27 Water supplies 150, 151 Lockport subseries 30, 39 Lodi member, Trempealeau forma- tion 30 Loess Ceramic raw material 142 Iowan and Peorian 104 Peorian, history 129 Soil formed from 151, 152 Vertical faces 105 "Loess-kindchen" 105 Lorraine quartzite 98, 127 Louisiana formation 30, 41 Lowell Park limestone, correlated with Decorah 37 "Lower Carboniferous" 41 "Lower Magnesian" 31 M Page McCartney mine Measured section No. 27 (Suite II) 117 Mine data 175 McKenzie River, advance of Devon- ian sea 41 Mack mine, mine data 174 McLaughlin, B., Coal reported by 137 Oil shows reported by 154 McLeansboro age postulated for Rock Island coal 63 McLeansboro formation 30, 47 McNeill mine, mine data 174 Madison City, Wisconsin 30 Madison formation Described 30 History 117 Martin (George) mine, mine data... 175 Martin (J. B.) mine, mine data 175 Matherville Clay tested 141 Coal 63 Coal, structure m Shipping mine 133 Marine sedimentation 20 Markley, J. H. Jr., assistance of 16 Maquoketa formation Classified 30, 31 Described 37-38 History 119 Not water-bearing 148 Structure 108-109 Mazomanie-Franconia formation Classified 30 Described 30 History 117 Mendota formation Described 30 History 117 Mendota Lake, Wisconsin 30 Meramec series 30, 41 Mercer County 15, 26 Chemical analyses of coal from 136 Mercer Township Pottsville formation, outcrops 51 Rock Island coal mined 133 Mesozoic group Classified 30 History 124 Milan quadrangle 14, 75 Structure of coal in Matherville district HI Milan town well, log 184 Mine data 173-176 Mine dumps, fossil collection locali- ties 157 Mines in Rock Island coal, areas of. 133 Mines, number working Rock Island coal in 1926 133 Mining methods 140 Minneapolis and St. Louis Railroad.. 27 INDEX — Continued 225 Page Minnesota Covered by Iowan glacier 128 Covered by Kansan glacier 126 Minnesota River 33 Miocene system 30 Mississippian system Classified 30 Described 41-46 Erosion of 121 History 120-121 Water-bearing 148 Mississippi River 109 Devonian outcrops along 40 Flood-plain, source of Peorian loess 129 Loess near 104 Pre-Pleistocene master stream.... 124 Valley aggraded 130 Mississippi Valley, glacial invasions. 125 Missouri, "Chattanooga" shale corre- lated with Sweetland Creek 43 Kansan glacier 126 Osage River in 45 Sweetland Creek formation in 42 Mohawkian series Classified 30, 31 Described 33-37 History 118 Molding sand 146 Moline, Illinois Dresbach formation, elevation 109 Eau Clair formation, thickness.... 30 Paper Mill Co. well, log 181 Structure south of 108 Trempealeau formation, thickness. 30 Tri-City Railway Co. well, log 184 Monmouth Clay Manufacturing Co. Pit 143 Plant 146 Monmouth, Illinois City well No. 2 (old), log 197 City well No. 4 (Geiger No. 1), log 198 City well No. 5 (Geiger No. 2), log 200 Dresbach formation, elevation 109 Monmouth quadrangle 14,16 Hannibal formation, thickness.... 43 Prairie du Chien series, thickness. 32 Strata of Suite IV exposed in 89 Structure north of 109 Sweetland Creek shale, thickness.. 42 Trempealeau formation, thickness. 30 Mountain Glen shale, correlated with Sweetland Creek 43 Mt. Simon formation Described 30 History 117 Oldest known formation 29 Water-bearing 148, 149 Murphysboro (No. 2) coal, base of Carbondale formation 78 N Page Natural gas, in glacial drift 127 Nebraska, Pennsylvanian sequences noted in 48 Nebraskan glacial epoch 126 Neverseen Coal Co. Mine data 173 Mine dump, fossil collections 157 Mines, measured sections 13, 14 (Suite II) 167 NeAV Gilchrist mine, mine data 176 New Richmond formation Classified 30 Described 32, 33 History 117 New Windsor, coal near 138 Niagara Falls, type locality of Niag- aran series 38 Niagaran series Classified 30 Described 38-39 History 110 Structure 109-110 Thinning of 40 Water-bearing 150 "Niggerheads" 59, S4 Noe, A. C, assistance of 15 North Henderson Creek Oil-test near 154 Peorian loess removed from valley 130 Soil on alluvial plain 153 Valley of 25 North Pope Creek Gilchrist shale along 141 Gilchrist shale and Rock Island coal near 75 Northwestern Clay Manufacturing Co 26 Fossil plants from pit 76 Gilchrist shale 141 Pit, geologic sections 16, 27 . .74, 101, 145 Plant .' 143, 145 Norwalk member, Trempealeau for- mation 30 Norwood, water supplies 150 O Ogle County, St. Peter sandstone, outcrops 33 Ohio, Pennsylvanian sequences noted in 48 Oil and gas, possibilities of 153 Oil field, Colmar 153 Oil-tests Former 154 Logs 194, 196 Recommended 155 Old Gilchrist mine, mine data 175 Old Gilchrist, mining town 26 "Old Red Sandstone" 38,39 Oligocene system 30 226 INDEX— Continued Page Oneota formation Classified 30, 32 Described 32 History 117 Ontario, quartzite from 127 Ordovices 31 Ordovician system Classified 30 Described .' 31-38 History 117 Overlain by Sweetland Creek for- mation 42 "Water-bearing 148 Orion city well, log 1 186 Oriskanian series 30 Osage River 45 Osage series Classified 30, 41 Subdivisions 45 Ottawa, St. Peter sandstone near. ... 33 Oxidation, in soil formation 153 Ozark Highland 116 P Paleobotany In Pennsylvanian correlation 47 Lepidodendron 55, 56 Pottsville formation, plants listed.. 70, 76 Sigillaria 56 Sporangites huronense 42, 43, 44, 120 Stigmaria, ' of no value in correla- tion 57 Paleontology Carbondale formation (Suite TV).. 89, 157-163 Fusulinella girtyi 63-64 Fusulinella sp 62 Girtyina ventricosa 63-64 Peorian loess, gastropods listed 105 Petroclus occidentalis 71 Pottsville formation (Suites I, II, HI) .' 157-163 Prodnctus nanus 63 Spirif er rockymonlana 63, 89 Taleozoic group Classified 29, 30 History 116 Parks Creek limestone, correlated with Suite II 64 Peat, Sangamon age 104 Pebble concentrates 102, 103 Pebble counts, Kansan and Ulinoian tills 99 Peneplain Dodgeville 124 Lancaster 124 Pliocene 125 Pre-Cambrian 116 Pennsylvania, coal-bearing rocks studied in 46 Pennsylvanian system (see also Car- bondale and Pottsville forma- tions) Page Basal conglomerate 44, 46, 77 Classified 30 Correlation of coals 63 Described 46-91 Distribution 46 Fossils, marine 63-64,89,157-163 Fossils, plant 55, 70, 76 History .121-124 Oil show reported from 154 Sandstones Overlying Hannibal shale 44 Valleys in 91 Water-bearing 150 Shale undifferentiated from Sweet- land Creek 42 Stratigraphic relations 46 Structures 111-114 Subdivisions 47-49 Thickness (maximum) 47 Water-bearing 149 Peoria, Illinois Farm Creek Pleistocene exposure near 104 Peoria quadrangle, Pennsylvanian sequences noted in 48 Peorian interglacial series 92 Depth of leaching 130 Described 104-106 Fossils listed 105 Geologic sections 21-30 93, 99-101, 103-105 History 129 Origin of name 104 Penetrated in coal-test boring 94 Removal from valleys 130 Water-bearing 149 Permian system Absent in Alexis quadrangle 29 Classified 30 History 124 Peterson mine, mine data 174 Physiography 23-26 Fiatteville formation 36 Classified 30, 31 Described 36 History 118 Oil possibilities 153 Water-bearing 148 Pleasant Valley Coal Co. mine, mine data 174 Pleasantview sandstone Classified 49 Described 90-91 History 124 Possible outcrop 82 Pleistocene system Classified 30 Described 92-106 History / . . .125-130 Overlying Pennsylvanian strata... 46 Overlying Sweetland Creek shale.. 42 Water-bearing formations 149, 150 INDEX — Continued 227 Page Pliocene peneplain 125 Pliocene period 125 Pliocene system 30 Poor, R. S., assistance of. 15 Pope Creek Coal along- 51, 139 Dammed by aggradation of Missis- sippi 130 Mine near 133 Outcrop of chert band along 71 Pottsville formation along tribu- taries to 50 Sandstone exposed along 82 Soil on terrace remnants 152 Valley of 25, 91, 124 Population, distribution of 26 Port Byron formation 30,39 'Potsdam" formation 31 Water-bearing 148 Potsdam, New York 31 Pottsville coals, local 133,138-140 Pottsville formation Classified 30 Conglomerate, basal 44, 77 Correlation 47-48 Described 50-78 Gilchrist shale (see Gilchrist shale) History 121-123 Rock Island coal (see Coal, Rock Island) Sandstone, conglomeratic 77 "Stigmarian" sandstone 49,56-57 Strata in Alexis quadrangle 49 Subdivisions 50 Suite I Composite 49 Deformation 113 Described 51-55 Fossils from limestone 157-163 Geologic sections 3, 4, 5, 6, 8, 11, 12 51, 52, 53, 65, 67, 68 History 121 Structure 113 Suite II Blue rock 62 Cap-rock 61 Described 55-64 Fossils . 157-163 Geologic sections 4, 5, 7, 8, 10-14, 16 ; Appendix B ..52, 53, 56, 65, 67, 68, 72, 74; 164-171 History 121-122 Rock Island coal 57 Shale, black 58 "Stigmarian" sandstone 56 Underclay of Rock Island coal.. 57, 141 Suite III Chert at lower unconformity 71 Composite 49 Described 64-76 Fossils 157-163 Page Geologic sections 4, 5, 7-17 52, 53, 56, 65, 67, 68, 72, 74, 76 Gilchrist shale 73 Sandstone, basal 70, 76 Suite IV Two members in Pottsville for- mation 77 Thickness, maximum 50 Undifferentiated strata 77 Pottsville, Pennsylvania 50 Prairie du Chien series Classified 30 Described 31-33 History 117 Relief developed in 117 Prairie du Chien, town of 32 Pre-Cambrian peneplain 116 Pre-Cambrian rocks 29, 31, 116 Source of glacial drifts 98 Preemption Twp., Rock Island coal mined 133 Preglacial Mississippi, course of 124 Treglacial surface 91 Preglacial valleys 23,91,124 Pre-Paleozoic eras in the Alexis quadrangle 116 Pre-IUinoian drainage channel 151 Pre-Illinoian sand, uses for 146 Pre-Pennsylvanian surface 46-47 Princeton, terminal position of Wis- consin ice 130 Prucha, A., assistance of 16 Pyrite, in Rock Island coal and roof. 58, 59 Pyritized fossils 60 Quarries 77, 78, 147 Quartz in Kansan and Illinoian tills. 99 Quartzite in Kansan and Illinoian tills 99 Quartzite, source of 127 Quartzitic conglomerate in Kansan and Illinoian tills 99 Quartz porphyry, in glacial drift. .. .20, 99 Quaternary sub-group 30 Quebec 127 Racine formation Recent system Classified Described , History Relief of Alexis quadrangle, ....30, 39 30 106 130 23 Rhyolite in Kansan and Illinoian tills 99 Richardson mine Measured section No. 26 (Suite II) 170 Mine data 175 Rock Island coal in 135 Rock Island Atlantic Brewery Co. well, log 1S2 228 INDEX— Continued Page Rock Island Brewing- Co. well, log". . 183 Rock Island coai (see Coal, Rock Island) Rock Island County- Devonian system, outcrops 39 Eau Clair formation in 30 Logs of wells in 177-185 Rock Island, Illinois 15, 39, 41, 57, 108 Mitchell and Lynde well, log 181 Modern Woodmen's well, log 182 Prairie du Chien series, thickness of 32 St. Peter formation, elevation of base 109 Rock Island Southern Railroad. 27, 143, 146 Rock River Devonian outcrops along 40 St. Peter sandstone along 33 Valley aggraded 130 Robbins, H. E., oil-test on farm 154 Room-and-pillar mining 140 Running water, work of 17 S St. Croix 29, 31 St. Croix River 29 St. Lawrence member, Trempealeau formation 30 St. Eouis formation 120 St. Peter formation Basal conglomerate 33 Classified 30 Described 33-34 History 118 Structure 108-109 Source of Alexis and Viola water supplies 149 Penetrated by wells 155 Water-bearing 148 St. Peters River 33 Sand, pre-Illinoian 146 Sand and gravel 146 Sand and gravel, water-bearing 151 Sandblast sand 146 Sandstone, conglomeratic 77 Sandstone in Kansan and Illinoian tills 99 Sandstone quarries 147 Sangamon interglacial series 92 Classified 30 Described 103-104 Geologic sections 21-29 93, 99-101, 103, 104 History 128 Sangamon Pwiver 103 Sangamon County, type locality of Sangamon interglacial deposits.. 103 Saverton shale 41 Schuyler County, type locality of Pleasantview sandstone 90 Schuler mine 138 Page Seaton village well, log 206 Sedalia formation 45 Sedimentation, marine 20 Senecan series 30 Seville, Illinois, type locality of No. 1 coal 63 Shakopee formation Classified 30 Described 32 History 117 Penetrated by oil-test 154 Shale City Brick plant at 26 Channel sandstone near Ill Coal in test-boring near 139 "Fault" reported near Ill Gilchrist shale near 141,142 Water supplies of Hydraulic Press Brick Co 150 Shale in Kansan atid Illinoian tills.. 99 Shale, resources 141 Sheffield, Illinois, coal considered Herrin No. 6 63 Sberrard high school well, log 186 Silures 38 Silurian system Classified 30 Described 38-39 History 119 Oil possibilities 153 Water-bearing 148, 150 Silvis City well, log 178 Continental Ice Co. well, log 178 Slope wash 106 Smith, Elder, oil-test on farm 154 Smith mine Measured section No. 22 (Suite II) 169 Mine data 175 Sriell mine Fossil collections, locality 2 157 Measured section No. 4 (Suite II). 165 Mine data 174 Rock Island coal in 135 Soils 106, 130, 151-153 "Spoon River" strata correlated with Suite I 55 Spoon River, type locality of No. 1 coal 63 Springfield (No. 5) coal 98 Spring Grove Twp. Burlington chert in glacial drift.. 98 Rock Island coai mined 133 Springs 151 Stagnant water, work of 18 State Asylum well, log 177 "Stigmarian" sandstone Above tilted strata 54 Classified 49 Coal below 138-139 Described 56-57 INDEX— Continued 229 Page Fossils 157-163 History 121 Structure, geologic Cedar Valley limestone 109,110 Colchester coal 112 Ice-shove 113, 127 Importance of 107 Devonian system, top 109, 110 Dresbach formation, top 109 Faults 113 Favorable to oil accumulation 154 Galena formation, top 108, 109 Maps, data used 107-109 Maquoketa formation, top 108, 109 Methods of determining 107 Methods of showing 107 Minor features 113 Niagaran series, top 1 09, 110 Pennsylvanian 111-114 Rock Island coal 111-112 St. Peter formation, base and top 108, 109 Structural deformation 121 Structural geology, defined 107 Subsidence due to coal mining 13 Suite (see Carbondale and Pottsville formations) Sumner Twp. Burlington formation quarried in sees. 32, 33, 34, 35 148 Swamps, Pennsylvanian 121 Sweetland Creek formation Classified 30 Described 42-43 History 120 Not water-bearing 148 Pre-Pennsylvanian lowland 47,121 Valleys in 91 Sweetland Creek, Iowa 42 Syenite in Kansan and Illinoian tills. 99 T Tennessee Chattanooga shale correlated with Sweetland Creek formation 43 Terrace remnants 25,26,152 Tertiary gravels 91, 98 Tertiary sub-group 30 Toms Creek 151 Transportation 27 Trempealeau Bluff, Mississippi River 30 Trempealeau formation Classified 30 Described 30 History 117 "Trenton" formation, possibly oil- bearing 153 Triassic system 30 Till, soil formed from 151, 152 Tully formation, correlation 40 Tully sea 120 U Page 30 Ulsterian series Underclay Below Colchester coal 83 Below Rock Island coal 57,141 Geologic sections 51-54, 56, 65-69, 72-76, 80, 90 In Pennsylvanian strata 49 Union County Devonian system, outcrops 39 Mountain Glen shale correlated with Sweetland Creek 43 United States Geological Survey.... 46 "Upper Carboniferous" 46 Upper Stones River series '.. 36 Valley flats, subject to flood 26 Valley-train deposits, water-bearing. 150 Valleys, preglacial 91 Valleys, width of 25 Vergennes sandstone, correlative of Pleasantview sandstone 91 "Vermicular" sandstone 43 Viola 26, 137 City well log 189 City well, no coal reported in 137 City well, penetrating St. Peter sandstone 155 Possibly underlain by coal 136 Transportation 27 Water supplies 149 W Waldo, A. W., assistance of 15 Wales 31, 38 Wanlock mine, mine data 175 Wanlock, mining town 26 Wapspinicon formation Classified 30 Described 40 History 120 Warren County, chemical analyses of coal from , 135 Warsaw formation 30, 45 History 120 Water supplies Analyses 148 Surface 151 Underground 148-151 Watertown, State Asylum well, log. . 177 Waukesha formation 30, 39 Waynesville, correlated with Galena. 38 Weathering 21 Weller, J. M., assistance of 16 Weller, Stuart, assistance of 16 Well logs 177-217 Wells 149-151 230 INDEX— Concluded Page "Williams mine Measured section No. 21 (Suite II) 169 Mine data 175 Rock Island coal in 135 Wind, work of 19 Wisconsin, age of loess 106 Wisconsin drift-plain, mantled with loesslike silt 106 Wisconsin glacial epoch 130 Wisconsin Madison and Mendota formations. 117 Pre-Cambrian peneplain 116 Workman, L. E., assistance of 15 Woodhull, village wells Nos. 1 and 2, logs 186, 187 Page Y Yarmouth interglacial series Classified 30, 92 Cross-bedded 96 Described 96-9S History 126 Penetrated in boring 94 Preservation of 127 Sand, spring at base of 151 Sands, water-bearing 149 Sieve analysis 148 Yarmouth, Iowa 98 ^,