•mr: THE UNIVERSITY OF ILLINOIS LIBRARY X b ^0 GEOLOGY DEPARTMENT OF THE INTERIOR UNITED STATES GEOLOGICAL SURVEY GEORGE OTIS SMITH, DIRECTOR BULLETINS Nos. 447-450 WASHINGTON GOVERNMENT PRINTING OFFICE 1911 4^^' ^ 0 Dro ^'PTirrnnoo CONTENTS Geological Survey bulletin 447; Mineral resources of Johnstown, Pa., and vicinity. Same 448; Geology and mineral resources of Nizina district, Alaska. Same 449; Geologic reconnaissance in southeastern Seward Peninsula and Norton Bay-Nulato region, Alaska. Same 450; Mineral resources of Llano-Burnet region, Texas. iii Digitized by the Internet Archive in 2016 https://archive.org/details/mineralresorceso4474phal DEPARTMENT OF THE INTERIOR UNITED STATES GEOLOGICAL SURVEY GEORGE OTIS SMITH, Director Bulletin 447 MINERAL RESOURCES OF JOHNSTOWN, PENNSYLVANIA AND VICINITY BY W. C. PHALEN AND LAWRENCE MARTIN SURVEYED IN COOPERATION WITH THE TOPOGRAPHIC AND GEOLOGIC SURVEY COMMISSION OF PENNSYLVANIA WASHINGTON GOVERNMENT PRINTING OFFICE 1911 CONTENTS, Page. Introduction 9 Geography 9 Location 9 Commercial geography 9 Topography 10 Relief 10 Surveys 11 Triangulation 11 Spirit leveling 13 Stratigraphy 14 General statement 14 Quaternary system 15 Recent river deposits (alluvium) 15 Pleistocene deposits 15 Carboniferous system 16 Pennsylvanian series 16 Conemaugh formation 16 General character 16 Detailed description 18 Wilmore sandstone member 18 Summerhill sandstone member 18 Morgantown (“Ebensburg”) sandstone member 19 Harlem (?) coal 19 Red shale 19 Saltsburg sandstone member 19 Buffalo sandstone member 20 Gallitzin coal 20 Lower red shales 20 Mahoning sandstone member 20 Allegheny formation 22 General character 22 Detailed description 25 Upper Freeport coal 25 Upper Freeport limestone member 25 Bolivar clay member 25 Butler sandstone member 25 Lower Freeport coal 25 Lower Freeport limestone member 25 Upper Kittanning (C 7 ) coal 25 Johnstown limestone member 26 Coals between Upper and Lower Kittanning coals 26 Lower Kittanning coal 27 Lower Kittanning clay member 27 Kittanning sandstone member 27 Brook ville and Clarion coals 27 Pottsville formation 27 3 4 CONTENTS. Stratigraphy — Continued. Page. Carboniferous system — Continued. Mississippian series 28 Mauch Chunk shale 28 Pocono formation 29 Devonian system , 29 Catskill formation 29 Structure 30 Mode of representation 30 Structure in the Johnstown quadrangle 31 General statement 31 Detailed description 32 Wilmore syncline 32 Viaduct anticline 33 Johnstown basin 33 Laurel Ridge anticline 33 Barnesboro or Westover syncline 34 Minor structures 34 Mineral resources 35 Introduction 35 Coal 35 General description 35 Upper Freeport coal 35 Lower Freeport coal 35 Upper Kittanning (C 7 ) coal 35 Lower Kittanning (Miller) coal 36 Character and importance 36 Coking tests 38 Miscellaneous tests 39 Lower Allegheny coals 7 39 Composition of the coals 40 Description by districts 42 Johnstown district 42 Extent 42 Conemaugh coals 43 Character and distribution 43 Gallitzin coal 43 Mahoning coal 43 Allegheny coals 44 Geologic position 44 Upper Freeport coal 48 Name and position 48 Extent and development 49 Chemical character 49 Occurrence and physical character 49 Lower Freeport coal 51 Name and position 51 Extent and development 51 Chemical character 51 Occurrence and physical character 52 Upper Kittanning coal 52 Name and position 52 Extent and development 53 CONTENTS. 5 Mineral resources — Continued. Page- Coal — Continued . Description by districts — Continued. Johnstown district — Continued. Allegheny coals — Continued. Upper Kittanning coal — Continued. Chemical character 54 Occurrence and physical character 56 Middle Kittanning coal 56 Lower Kittanning coal 57 Name and position 57 Extent and development 57 Chemical character 58 Occurrence and physical character 58 Lower coals 60 Pottsville coals 61 South Fork-Mineral Point district 61 Extent * 61 Geologic position of coals 62 Conemaugh coals 62 Coal near Summerhill 62 Gallitzin coal 64 Allegheny coals 64 Upper Freeport coal , 64 Name and position 64 Extent and development 65 Chemical character 65 Occurrence and physical character 66 Lower Freeport coal 67 Upper Kittanning (Cement) coal 67 Name and position 67 Extent and development 67 Chemical character 67 Occurrence and physical character 68 Lower Kittanning (Miller) coal 69 Name and position 69 Extent and development 69 Chemical character 69 Steaming tests 70 Coking tests 72 Cupola tests 73 Producer-gas tests 76 Occurrence and physical character 76 Lower Allegheny coals 77 Pottsville coals 78 Blacklick Creek district 78 Extent : 78 Geologic position of coals 79 Allegheny coals 80 Lower Freeport (D) coal 80 Name and position 80 Extent and development 81 Occurrence and physical character 81 6 CONTENTS. Mineral resources — Continued. Page. Coal — Continued . Description by districts — Continued. Blacklick Creek district — Continued. Allegheny coals — Continued. Middle Kittanning (C) coal 82 Lower Kittanning (B) coal 82 Name and position 82 Extent and development 83 Chemical character 83 Steaming tests 83 Coking tests 85 Producer-gas test 86 Washing tests 86 Briquetting tests 87 Occurrence and physical character 88 Lower Allegheny coals 89 Windber district 91 Extent 91 Geologic position of the coals 91 Allegheny coals 92 Upper Freeport (E) coal 92 Lower Freeport (D) coal 93 Upper Kittanning (C') coal 93 Middle Kittanning (C) coal 94 Lower Kittanning (Miller or B) coal 94 Name and position 94 Extent and development 94 Chemical character 95 Occurrence and physical character 95 Lower Allegheny coals 95 Conemaugh Furnace district 96 Extent 96 Allegheny coals 96 Upper coals 96 Lower Kittanning (B) coal 97 Extent and development 97 Chemical character 97 Steaming tests 98 Coking tests 98 Washing tests 99 Briquetting tests 99 Occurrence and physical character 101 Coal mining 102 Room and pillar system 102 General description 102 Ventilation 104 Drainage 104 Haulage 104 Mining methods 105 Long wall system 105 Literature 113 CONTENTS. 7 Mineral resources — Continued. Pa 8 e - Clay and shale - 113 Mode of treatment 113 General description 113 Flint clays 113 Plastic clays 114 Shales 115 Description by districts 115 Johnstown district 115 Flint clays 115 Plastic clay 117 Shales 119 South Fork district 121 Flint clays 121 Plastic clay 123 Shales 123 Blacklick Creek district 124 Flint clay 124 Plastic clay 125 Miscellaneous localities 125 Production 125 Brick industry 126 Limestone and cement materials 126 Extent 126 Upper Freeport limestone member 126 Lower Freeport limestone member 126 Johnstown limestone member 127 Building stone, paving blocks, and concrete materials 129 Glass sand 131 Iron ores 132 History 132 Johnstown ore bed 132 Extent 132 Character of the ore 133 Physical features of the bed 134 Water resources 136 Index 137 ILLUSTRATIONS. Page. Plate I. Economic and structural map of the Johnstown quadrangle, Penn- sylvania In pocket. II. Key map showing the location of the Johnstown quadrangle with reference to the entire Appalachian coal field 9 III. A, South Fork and washed away dam; B, Sandstone near base of Conemaugh formation near Johnstown 20 IV. A, Exposure of Lower Freeport coal on Stony Creek near trolley bridge, B, Country bank of the better class on the Upper Kit- tanning coal near Mineral Point. 24 8 ILLUSTRATIONS. Page Plate V. A, Typical exposure of Mauch Chunk shale at the viaduct between South Fork and Mineral Point; B, Shale quarry of B. H. Campbell, north of Sheridan, at the Mercer horizon 28 VI. A, Detailed structure of the Loyalhanna limestone; B, Loyalhanna limestone (top member of Pocono formation) at summit of Ebens- burg (Viaduct) anticline, Mineral Point 28 VII. A, Exposure of Upper Kittanning coal and Johnstown limestone member on Stony Creek, near mine of Valley Coal and Stone Com- pany; B, Upper Freeport coal and overlying shales and base of Mahoning sandstone at the south portal of the Baltimore and Ohio Railroad tunnel, Stony Creek 48 Figure 1. Sketch map showing location of triangulation stations on which survey of Johnstown quadrangle is based 11 2. Skeleton sections showing coals in Allegheny formation and the intervals between them 24 3. Sketch showing the great irregularity in detail of the structure in parts of the Johnstown quadrangle and the marked regularity in detail in other parts 31 4. Sections of the Upper Freeport (E or Coke Yard) coal in the Johns- town district 50 5. Sections of the Lower Freeport (D or Limestone) coal in the Johns- town district 52 6. Sections of Upper Kittanning (O' or Cement) coal in the Johnstown district 55 7. Sections of the Lower Kittanning (Miller or B coal) in the Johns- town district. . . : 59 8. Section of Clarion (A 7 ) coal in the Johnstown district 61 9. Sections of Upper Freeport (E or Lemon) coal near South Fork 66 10. Sections of Upper Freeport coal along the southeastern margin of the Wilmore Basin 66 11. Sections of Upper Kittanning (Cement or C / ) coal in South Fork- Mineral Point district 68 12. Sections of Lower Kittanning (Miller or B) coal in South Fork- Mineral Point district 77 13. Section of the Brookville (A) coal at mine of J. H. Wickes, South Fork . 78 14. Sections of Lower Freeport (D) coal along Blacklick Creek 81 15. Sections of Lower Kittanning (Miller or B) coal in the Blacklick Creek district 89 16. Sections of Upper Kittanning (Cement or CO coal in the Windber district 93 17. Sections of Lower Kittanning (Miller or B) coal in the Windber district 95 18. Sections of Lower Kittanning (Miller or B) coal in Conemaugh Furnace district 101 19. Diagram illustrating the room and pillar method of mining in the Johnstown quadrangle 103 20. Plan showing long- wall method of mining as employed at Vinton collieries Nos. 1 and 3, Vintondale 106 21. Plan of workings, single long- wall conveyor system 107 22. Plan of workings, triple long- wall conveyor system 108 U. S. GEOLOGICAL SURVEY BULLETIN 447 PLATE II KEY MAP SHOWING LOCATION OF THE JOHNSTOWN QUADRANGLE WITH REFERENCE TO THE ENTIRE APPALACHIAN COAL FIELD. MINERAL RESOURCES OF JOHNSTOWN, PENNSYLVANIA, AND VICINITY. By W. C. Phalen and Lawrence Martin. INTRODUCTION. This report is one of a number of bulletins and geologic folios containing the results of geologic investigations carried on by the United States Geological Survey in cooperation with the Topographic and Geologic Survey Commission of Pennsylvania. Several papers based on this work, for which the State paid one-half the cost, have been or will soon be published by the State; others are in prepara- tion for publication by the United States Geological Survey. The field work on which this bulletin is based was done in the summer of 1906 by W. C. Phalen, assisted by Lawrence Martin. George H. Ashley, under whose supervision the work was done, visited the field and went over some of the more critical points. GEOGRAPHY. Location . — The Johnstown quadrangle is situated in southwest- central Pennsylvania, mostly in Cambria County, but extending also over small parts of Somerset, Westmoreland, and Indiana counties. (See PI. I, pocket.) Its area is about 228 square miles. It lies near the eastern edge of the Allegheny Plateau province and near the northeastern edge of the great bituminous coal field that extends from the southern part of New York to northern Alabama; its position in this fieldis shown in Plate II. Commercial geography . — This quadrangle lies in the plateau region west of the Allegheny Front. Its most important streams areCone- maugh River (formed by the union of Stony Creek and Little Cone- maugh River at Johnstown), Blacklick Creek and its South Branch, and South Fork of Conemaugh River. Conemaugh River has long afforded one of the most available highways of communication across the region from the coast to the Middle West; the first railroad (the old Portage and Canal route) and the main line of the Pennsylvania Railroad have both used this valley. The development of the iron 9 10 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. resources of the region was thus early stimulated, and in turn an impetus was given to the development of the coal resources, until at the present time Johnstown and the neighboring towns are among the leading coal and iron centers of western Pennsylvania. Stony Creek flows northward, in its course forming part of the boundary between Somerset and Cambria counties, this part of its course lying entirely within the Johnstown Basin. The South Fork of Conemaugh River heads near the summit of Allegheny Mountain, near the Cambria-Bedford county line in the Ebensburg quadrangle, which adjoins the Johnstown quadrangle on the east. South and North branches of Blacklick Creek join near Vintondale and the main stream continues westward along the northern edge of the area. In a general way the drainage of the quadrangle flows from east to west. The main structural and to a less noticeable extent the main topographic features trend northeast and southwest. The drainage and structure thus intersect at a fairly large angle — a condition which has proved of vast economic importance, for it has resulted in the cutting of deep valleys and the exposing of valuable clay and coal beds. Moreover, it has made possible the exploitation on a large scale of the mineral wealth by drifting along the outcrop — a much safer and cheaper method than shafting and one tending to the most rapid development of a coal region. The streams have determined the location of the local railway systems and have made their con- struction fairly easy. TOPOGRAPHY. RELIEF. The form of the surface of the Johnstown quadrangle bears a close and striking relation to the geology and structure. The highest points in the area are along the crest of Laurel Ridge, which south of Conemaugh River is more than 2,700 feet high at a few points. Laurel Ridge is a structural feature — that is, it is dependent on the character of the rocks brought to the surface by the structure. These are largely the sandstones of the Pocono and Pottsville formations. Where rocks of this character cover the surface the country is wild and surface cultivation is out of the question. Farther north along the ridge the sandy sediments dip below drainage level and the rocks of the Allegheny formation (“ Lower Productive Coal Measures”) and the Conemaugh formation (“Lower Barren Coal Measures”) appear in the hills, as, for instance, along South Branch of Blacklick Creek. The changes in vegetation and general conditions accompanying the gradual disappearance of the sandy beds below the surface are notice- able north of South Branch of Blacklick Creek, and in this region the country is almost all under cultivation. In the southeast corner of the quadrangle the highest hills are a little more than 2,700 feet high. Here also the beds are involved in TOPOGRAPHY. 11 the structural uplift along the front of Allegheny Mountain, and the rocks along the crest of the mountain are chiefly the same sand- stones as occur on Laurel Ridge. The lowest points in the area are on Conemaugh River, at the west- ern edge of the quadrangle. At Conemaugh Furnace station the elevation is 1,134.54 feet. The extremes in the topography are well brought out near by, for Conemaugh River in descending from 1,185 feet at Johnstown to 1,135 feet at Conemaugh Furnace flows through a gorge the hills on either side of which rise 1,600 feet higher. The greater portion of the area has an elevation between the extremes given above. In detail the surface is decidedly hilly, but most of the hill slopes are rather gentle, especially back from the main drainage channels. The badly dissected character of the ridge has, however, an important bearing on the availability and exploita- tion of the natural resources of the region. There is very little level land in the quadrangle, what there is being confined almost solely to the lower stretches of Blacklick Creek in Indiana County. Points of equal elevation are represented on the contour map by light-brown lines, which really represent the intersections of hypo- thetical horizontal planes with the surface of the country. They are placed 20 feet apart and indicate the “lay of the land” with great precision. SURVEYS. TRI ANGULATION STATIONS. The topographic work for the map of the Johnstown quadrangle (PI. I) is based on triangulation stations established by the United States Geological Survey within the boundaries of the quadrangle or comparatively near its borders to the east and north. (See fig. 1.) Descriptions of the exact locations of these triangulation stations are given below: CHICKAREE, CAMBRIA COUNTY. On a cleared knob in the central part of Jackson Township, 10 miles by road westward from Ebensburg, 300 yards south of the Chickaree Hill schoolhouse. Station mark: A marble post 34 by 6 by 6 inches set 32 inches in the ground, in the center of top of which is countersunk and cemented a bronze triangulation tablet. Figure 1 . — Sketch map showing location of tri- angulation stations on which survey of Johns- town quadrangle is based. 12 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. [Latitude 40° 26' 38.97". Longitude 78° 52' 48.29".] To station — Azimuth. Back azimuth. Log. dis- tance. Ebensburg 251 24 48.82 292 00 35.81 318 31 18.78 71 30 51.47 112 04 41.22 138 37 47.50 Meters. 4. 1425539 3. 9833693 4. 3303852 Wess Fye EBENSBURG, CAMBRIA COUNTY. Station is center of cupola of courthouse in Ebensburg. Station mark: Center of cupola. [Latitude 40° 29' 02.07". Longitude 78° 43' 29.50".] To station— Azimuth. Back azimuth. Log. dis- tance. o tt o / // Meters. Thomas 156 58 25.25 336 57 06. 21 3. 8644894 Carrolltown 185 49 38. 40 5 50 15.62 4. 1222362 Wopsononock 248 52 46. 94 69 03 52. 34 4. 4120176 Tunnel Hill 270 56 22. 25 91 03 22. 64 4. 1833793 Sherbine 0 52 21.75 180 52 15.82 4. 1515885 Wess 27 55 04. 38 207 53 07. 38 3. 9581867 Chickaree 71 30 51.47 251 24 48.82 4. 1425539 WESS, CAMBRIA COUNTY. In the northern portion of Croyle Township, 8 miles southwest of Ebensburg, 1 mile west of New Germany, in a pasture owned by Leo Wess. Theodolite elevated 35 feet. Station mark: A marble post 36 by 6 by 6 inches set 32 inches in the ground, in the center of the top of which is countersunk and cemented a bronze triangulation tablet. Reference mark: Line fence due north 44 feet distant. Center of big dead tree, N. 65° W. (magnetic), 31 feet distant. [Latitude 40° 24' 41.86". Longitude 78° 46' 29.85".] To station— Azimuth. Back azimuth. Log. dis- tance. Chickaree 112 04 41.22 185 20 37.23 207 53 07.38 326 41 29.11 337 09 43.27 Of If 292 00 35.81 5 21 15. 32 27 55 04.38 146 43 20.03 157 12 06.81 Meters. 3. 9833693 4. 1710473 3. 95&1867 3. 8666773 4. 1299536 Thomas Ebensburg Sherbine Fye SHERBINE, CAMBRIA COUNTY. On a small hill having scattering locust trees on its summit, in Croyle Township, about one-fourth mile west of the Summerhill Township line, 2 miles southwest of Wilmore, 2 miles southeast of Summerhill post-office, on land of Aaron Sherbine. Theodolite elevated 28 feet. TOPOGRAPHY. 13 Station mark: A marble post 36 by 6 by 6 inches set 32 inches in the ground, in the center of top of which is countersunk and cemented a bronze triangulation tablet. [Latitude 40° 21' 22.50". Longitude 78° 43' 38.65".] To station— Azimuth. Back azimuth. Log. dis- tance. Wess 146 43 20.03 180 52 15.82 228 00 07.85 349 15 37.33 326 41 29.11 0 52 21.75 48 07 13.50 169 16 09.98 Meters. 3. 8666773 4. 1515885 4. 3183273 3. 8058254 Ebensburg Tunnel Hill Fye FYE, CAMBRIA COUNTY. [Not occupied.] A cleared ridge known as the Fye place, owned by the Mountain Coal Company, in Adams Township, 6 miles south of Summerhill and 7 miles southeast of South Fork. Station mark: A marble post 36 by 6 by 6 inches set 32 inches in the ground, in the center of top of which is countersunk and cemented a bronze triangulation tablet. Reference mark: The lone locust signal tree 4 feet north of station mark. [Latitude 40° 17' 58.79". Longitude 78° 42' 48.19".] To station— Azimuth. Back azimuth. Log. dis- tance. Chickaree Wess 138 37 47.50 157 12 06.81 169 16 09.98 318 31 18.78 337 09 43.27 349 15 37.33 Meters. 4. 3303852 4. 1299536 3. 8058254 Sherbine SPIRIT LEVELING. The topography of the Johnstown quadrangle is shown on Plate I by buff-colored contour lines based on precise levels run by the United States Geological Survey. In running these levels numerous bench marks were established, their elevations being based on an aluminum tablet in the foundation of the Seventh Avenue Hotel, Pittsburg, Pa., marked “ 738 Pittsburg, 1899,” the elevation of which is now accepted as 738.384 feet above mean sea level. The initial points on which these levels depend are various bench marks along the precise-level lines of the Pennsylvania Railroad, the accepted heights having been determined by the 1903 adjustment. The work on the Johnstown quadrangle was done by Mr. George Seidel, levelman, in 1902. 14 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. The descriptions and elevations of these bench marks are given below: Johnstown south along Baltimore and Ohio Railroad to Ingleside. Feet. Johnstown, at west end of north parapet of railroad bridge; copper bolt (Pennsylvania Railroad bench mark) ], 180. 27 Johnstown, east end of south parapet of Pennsylvania Railroad bridge; aluminum tablet stamped “1180 PITTS ” 1, 180. 261 Johnstown, railroad ticket office, on window sill; chiseled shelf (Pennsyl- vania Railroad bench mark) l } 187. 60 Johnstown, road crossing at Pennsylvania Railroad station; top of rail 1, 184 Johnstown, in front of Baltimore and Ohio Railroad station; top of rail 1, 169 Stony Creek, road crossing at station; top of rail 1, 194 Johnstown, 3 miles south of, Baltimore and Ohio Railroad and trolley grade crossing; top of rail 1, 191 Kring, road crossing at station; top of rail 1, 241 Ingleside, 700 feet north of, northeast corner of small railroad bridge; cop- per bolt marked “1275 PITTS ” 1, 275. 610 Ingleside northeast along Pennsylvania Railroad via Elkton to Salix. Scalp Level, 0.45 mile north of, west side of track, 75 feet west of tool house. in large sandstone; aluminum tablet stamped “1719 PITTS ” 1, 719. 225 Salix, 870 feet north of station, under Pennsylvania Railroad culvert, west wall; bronze tablet stamped “2050 PITTS” 2, 049. 455 Salix, railroad bridge at station, north parapet, east end; aluminum tablet stamped “2077 PITTS” 2,077.762 Seward northeast along Pennsylvania Railroad via Vintondale and Nanty Glo to Ebensburg. Seward, 0.17 mile west of V. K. tower, railroad bridge No. 226 over Piney Run, north parapet, east end of arch; copper bolt (Pennsylvania Railroad bench mark) 1, 091. 571 Seward, doorstep of waiting room of station; copper bolt marked “1122 U. S.” 1,122.145 Seward, crossing at station; top of rail 1, 120 Wehrum, crossing at station; top of rail 1, 360 Vintondale, 150 feet east of station, iron bridge, south end of west abutment; aluminum tablet stamped “1403 PITTS ” 1, 402. 741 Twin Rocks, crossing at station; top of high rail 1, 668 Nanty Glo, 200 feet south of station, iron bridge, west end of north abutment; bronze tablet stamped “1706 PITTS ” 1, 705. 761 Nanty Glo, crossing at station; top of high rail 1, 710 Beulah Road, in front of station; top of rail 1, 894 STRATIGRAPHY. GENERAL STATEMENT. The surface rocks in the Johnstown quadrangle are entirely of sedimentary origin, all of them having been deposited in or by water. They consist of sandstones, shales, limestones, and coal and iron-ore beds, the whole having a thickness of approximately 3,100 to 3,200 STRATIGRAPHY. 15 feet. These rocks belong in the Devonian and Carboniferous systems, except for the imperfectly consolidated gravels of the river terraces, which are tentatively regarded as of Pleistocene age, and the recent alluvium of the flood plains. The Carboniferous rocks are of chief importance, as they contain the workable coals and clays. All these rocks will be described in descending order, beginning with the youngest. QUATERNARY SYSTEM. RECENT RIVER DEPOSITS (ALLUVIUM). The alluvium of the streams of this area is the youngest bedded deposit. It consists of fine material, chiefly sand and clay, laid down by the present streams during periods of high water, and is present in varying amounts along most of the streams, though occupying as a rule small areas only. The most important alluvial area is that at the confluence of Conemaugh River and Stony Creek, on which the greater part of the city of Johnstown and its suburbs is located. Other important areas of alluvium are found on Blacklick Creek near the northwestern corner of the quadrangle. All the level land in this part of the quadrangle is under cultivation. PLEISTOCENE DEPOSITS. Along Conemaugh River and Stony Creek occur deposits which can not be correlated strictly with the alluvium or recent flood-plain deposits. This material, which consists of rounded bowlders varying up to 2 or 3 feet in greatest dimension, mingled with sand and clay in small quantities, is found at two or more distinct horizons. The lower deposit is well developed along the main line of the Pennsylvania Railroad and is shown in small cuts a short distance east of Mineral Point. On the Baltimore and Ohio Railroad a short distance south of the quadrangle, north of the mouth of Paint Creek, near Kring, and near the suburb of Roxbury are also excellent exposures. At the quarry of B. H. Campbell, north of Sheridan, rounded bowlders occur 100 feet above the level of the Pennsylvania Railroad. This deposit is similar in all respects to the lower one occurring along Stony Creek. These bowlders show in the foreground of Plate V, B (p. 28). The material is considered to be Pleistocene in age. It has no economic importance. 16 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. CARBONIFEROUS SYSTEM. PENNSYLVANIAN SERIES. CONEMAUGH FORMATION. GENERAL CHARACTER. The Conemaugh formation includes the rocks lying below the Pitts- burg coal and above the Upper Freeport coal. A nearly complete section of these rocks was obtained from drill records and by hand- level work along the Pennsylvania Railroad in the deepest part of the Wilmore structural basin. The upper 200 feet or so of the section represents barometric work along the roads in the Ebensburg quad- rangle to the east. It has been thought advisable to give the section of the Conemaugh thus obtained in this locality as a matter of record, but it will be understood that such a detailed section necessarily is constant over a very small area. Some of the sandstones, for instance, die out completely within a short distance and other lentils appear in the section either slightly higher up or lower down. In general, local names are applied to such sandstone lentils where their position is known to be fairly well defined in the geologic column. The section of the Conemaugh formation is as follows : Section of the Conemaugh formation in the Wilmore Basin. a Sandstones and sandy shale layers with intercalated limestones Shale Sandstone (Wilmore) Shale Limestone, sandy Shale, green, weathering to clay Shale, dark drab Sandstone, containing a 10 to 12 inch limestone layer and with a possible coal bloom. . Shale Limestone Shale, green Limestone Shale, concretionary Fireclay Shale, concretionary Shale, olive Shale, dark Sandstone Shale, blue-black Limestone Shale Sandstone (Summerhill) Shale, with sandy and limestone layers Sandstone, shaly Shale, dark blue, weathering like sandstone Sandstone Limestone Limestone grading into sandstone Sandstone, hard, grav. .) Shale [Morgantown (“ Ebensburg”) sandstone member Sandstone, hard, gray . . J Shale, sandy Sandstone Thick- ness. Total. Ft. in. Ft. in. 200« 200 20 220 17 237 5 242 2 244 23 267 15 282 6 288 10 298 9 307 6 313 1 314 2 316 1 317 4 321 1 322 10 332 1 333 3 336 3 339 20 359 45 404 30 434' 25 459 25 484 2 486 3 489 6 495 1 25 520 520 3J 1 7 5J 527 9 3 2 530 11 5 1 536 a First 200 feet, barometric measurements along roads; section hand-leveled from 200 to 495 feet; below 495 feet record obtained from a bore hole on the Pennsylvania Railroad opposite the signal tower between Wilmore and Summerhill. CARBONIFEROUS SYSTEM. 17 Section of the Conemaugh formation in the Wilmore Basin — Continued. Thick- ness. Total. Ft. in. Ft. in. 9 24 10 545 24 Coal (called 600-foot rider owing to its position at about 600 feet above the Lower Kittanning or B coal) 546 4 Shale 29 2 575 2J 581 34 588 101 607 2\ 613 10| 6 1 Shale' 7 7 Sandstone and shale 18 4 Shale, calcareous 6 8 Shale'with calcareous and clay streaks 13 2 627 \ Shale, sandy 8 10 635 104 Shale 3 5 639 3| 6 104 7 10“ 646 2 Shale, sandy 654 Sandstone 31 2\ 8 685 24 Shale, with bony streaks 685 104 701 4 Sandstone 15 5J 4 10i f 19 Shale 706. 24 Shale, sandy. ] 725 24 Sandstone >Buffalo sandstone member J 28 1 753 34 Slate and sandstone. . J l 12 3 765 6| Sandstone with congomerlate layers 55 24 820 9 Slate 4 3 825 Slate, sandy 7 6 832 6 Slate 28 64 7 6|- m 861 4 Slate, sandy 868 7 Shale 869 64 874 4 Slate, sandy 4 6" Slate 11 7J 885 8 Sandstone 3 4 889 Shale 10 3 899 3 Shale, red 4 11 904 2 Sandstone 10 3 914 5 Shale 8 3 922 8 Sandstone 2 81 21 6 925 44 Shale with sandstone layers 946 104 947 10 Sandstone HI 1 3 Slate 949 1 Sandstone 10 1 959 2 Slate 5 964 2 Top of Upper Freeport coal. With this section may be compared the following section of a part of the Conemaugh, measured by John Fulton, in Prossers Knob, near Johnstown:® Section of part of the Conemaugh formation in Prossers Knob, near Johnstown. Ft. in. Stone quarry ; sandstone 20 Shales, olive 17 Shales, drab 18 Sandstone, thin bedded 10 Shales 8 Iron ore, siliceous 3 Shales, olive and drab 68 Shales, red 10 Shales, olive 12 Slate and sandstone 10 Sandstone-, white 26 Shales, drab 13 Sandstone, massive, drab, forming cliff 20 Coal 3 a Second Geol. Survey Pennsylvania, Rept. H2, p. 97. 69516°— Bull. 447—11 2 18 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Shale, drab Sandstone, drab Slates Johnstown iron-ore seam Shales, flesh and drab colored. Shales, iron stained Iron ore Fire clay Shales, soft, drab Fire clay and shales Shales, drab, and sandstone ... Coal, Upper Freeport or E Place of the Mahoning sand- stone. Ft. 4 7 2 2 13 9 2 8 4 15 3 in. 10 According to the section (pp. 16-17), the Conemaugh is nearly 1,000 feet thick, this estimate, however, being subject to the question of the correct correlation of the Pittsburg coal. It is made up essentially of shales and sandstones, with a few beds of limestone. Streaks of coal are present here and there, hut only locally are they of sufficient thickness and purity to be worked even in a small way. Fire clay, both plastic and flint, occurs in the formation in certain parts of the area. A bed of iron ore described in the reports of the Second Geo- logical Survey of Pennsylvania as the Johnstown ore has been found on Mill Creek, north and west of Johnstown, and near the position of the old Cambria furnace at the base of Laurel Hill; it lies 50 feet above the Upper Freeport coal. Considerable historical importance attaches to this ore body, for its presence determined the beginning of the iron industry near Johnstown and undoubtedly influenced the present vigorous development of the coal. DETAILED DESCRIPTION. The higher portion of the Conemaugh in the Johnstown quadrangle is made up of sandstones and shales, with occasional beds of limestone. As it has been found difficult to correlate these sandstones with the typical members in the Pittsburg district and Allegheny Valley, they .are here referred to by the local names given them in the Ebensburg quadrangle, which lies immediately east of the area under discussion. Wilmore sandstone member . — The highest of these sandstones was called by Butts a the Wilmore sandstone. It shows in the top of the first railway cut west of Wilmore and in the neighboring hills. Its position with reference to the Upper Freeport coal is indicated in the section on pages 16-17. It is usually not more than 20 feet thick. Summerhill sandstone member . — Next comes the Summerhill sand- stone member, whose base lies 560 feet above the Upper Freeport coal. It varies from 30 to 45 feet in thickness. It was named by Ebensburg folio (No. 133), Geol. Atlas U. S., U. S. Geol. Survey, 1905, p. 5. CARBONIFEROUS SYSTEM. 19 Butts from the village of Summerhill, in the eastern part of the Johnstown quadrangle. It outcrops conspicuously in all the hills between Wilmore and Summerhill, especially in a bluff east of the latter town. It is as a rule decidedly laminated in appearance, differ- ing in this respect from the massive Morgantown (‘ ‘Ebensburg”) sand- stone below. Morgantown ( (C Ebensburg”) sandstone member. — The next lower stratum of note in this area is a sandstone which Butts called the Ebensburg, but which in this report will be termed the Morgantown sandstone member. This sandstone lies between 400 and 450 feet above the Upper Freeport coal in the southeastern part of the quad- rangle and probably less than 400 feet above it in the northern part. It is excellently developed near Elton in the Johnstown area. Harlem ( ?) coal. — The Morgantown sandstone is closely underlain by a thin coal known as the 600-foot rider, as it is usually 600 feet above the Lower Kittanning coal. It outcrops near the old dam site on South Fork of Conemaugh River (PL III, A). It is possible that this corresponds to the Harlem or Friendsville coal, but this correlation is provisional, as it is hazardous to attempt close corre- lation with the upper portions of the Conemaugh in the western part of the State. Red shale. — The next lower stratum persistent enough to be traced with certainty is a band of red shales 30 feet or less in thickness. These occur in nearly all parts of the quadrangle, though the distance of their top above the Upper Freeport coal is not constant, varying from 300 to 400 feet. They may correspond to the red shale in the western part of the State, to which I. C. White has given the name Pittsburg red shales. Saltsburg sandstone member. — Around Johnstown the top of what is regarded as the representative of the Saltsburg sandstone member lies about 300 feet above the Upper Freeport coal. It is very nearly 50 feet thick and is fairly massive in the hills east of the town. It is underlain in this region by a thin band of reddish and purple shales. In the southeastern part of the quadrangle the Saltsburg horizon is for the most part below drainage level, but several apparently carefully kept drill records give an excellent idea of its character. Its top is here 300 feet' above the, Upper Freeport coal, and it is about 50 feet thick. It is underlain by 30 to 40 feet of shales containing a coal (the Bakerstown bed) or, in one section, two coals separated by 25 feet of shales and sandy shales. Red shale also appears in this shale interval, and not more than 25 feet above this a slightly cal- careous bed, very thin, may possibly represent the Upper Cambridge limestone. Both near Johnstown and in the southeastern part of the quadrangle these sandstones in places become sandy shales and 20 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. merge imperceptibly with the beds above or below, so that it is diffi- cult or impossible to locate their bases and tops in the records. Buffalo sandstone member. — In the South Fork district the top of the Buffalo sandstone member is about 200 feet above the Upper Freeport coal. As nearly as can be ascertained from the road sec- tions, the sandstone consists of a single member. It appears promi- nently along the Pennsylvania Railroad near Ehrenfeld, where the debris from it is massive, and is well exposed in the shallow railroad cuts west of Summerhill station. Compactly bedded thick and thin flags are very characteristic of this stratum in the eastern part of the Johnstown quadrangle and farther east in the Ebensburg quadrangle. Along Blacklick Creek in the northwestern part of the quadrangle there appears in the section a very massive sandstone, whose top is 200 to 235 feet above the Lower Freeport coal and 80 and 95 feet, respectively, above the Mahoning coal and Johnstown ore bed. This sandstone probably corresponds to the Buffalo sandstone member. It is exceedingly massive, forming debris comparable to that from the Pottsville. It makes a very prominent appearance north of Vintondale and to the west in Indiana County. Gallitzin coal. — The Gallitzin coal ranges from 70 to 125 feet above the top of the Upper Freeport coal in the region around Johnstown. In some of the diamond-drill records from the hills east of the city it appears about 110 feet above the top of the Upper Freeport coal. In some of the sections a coal appears as near the Upper Freeport as 70 feet. Where there is but a single coal in the lower 125 feet of the Conemaugh and it is as near to the Upper Freeport as 70 feet there is always doubt as to whether it should be regarded as the Gal- litzin or as a lower coal. The Gallitzin coal is not a commercial bed and has not been worked except for local use in any part of the quadrangle. Lower red shales. — The Gallitzin coal is underlain by a thin band of red or variegated shales, which are well exposed along the road ascending to Pleasant Hill in the western part of Johnstown. In some records of the drill holes put down to the east of the city these shales have been called variegated. Mahoning sandstone member. — The Mahoning member is composed of sandstones, shales, and coals tying at the base of the Conemaugh formation between the Gallitzin coal and the Upper Freeport coal (top of the Allegheny formation). It is Well exposed in the hills about Johnstown and to the south along Stony Creek, near South Fork, and near Blacklick Creek. At the tunnel of the Baltimore and Ohio Railroad south of Johns- town the following clear-cut section of the lower part of this member was obtained : U. S. GEOLOGICAL SURVEY BULLETIN 447 PLATE III A. SOUTH FORK AND WASHED AWAY DAM. The breaking of this dam caused the Johnstown flood of May 31,1 889. B. SANDSTONE NEAR BASE OF CONEMAUGH FORMATION NEAR JOHNSTOWN. CARBONIFEROUS SYSTEM. 21 Section of part of Mahoning sandstone member south of Johnstown , Pa. Ft. in. Sandstone, laminated and cross-bedded, upper Mahoning 8 Shale, green 4 -5 Coal 5 Shale, drab, fossiliferous 2 Coal 6 Fire clay, dark, almost black 6 Limestone, blue, ferruginous, altering to ore (“ Johnstown ore”) 1^-2 Shale 30 Sandstone, massive 20 Shale, massive, brown 5 This section may be considered fairly typical for this immediate region. The upper sandstone, called upper Mahoning, is decidedly characteristic in appearance. It is fine grained, weathering into extremely thin slabs, and where seen to greatest advantage ranges in thickness up to 20 feet. The coal below it, exposed in the saddle in the road above the tunnel, is present in two benches with an inter- val of 2 feet between. This is probably the Mahoning coal. It is nowhere of workable thickness in this quadrangle. The “Johnstown ore” underlies the Mahoning coal and is about 50 feet above the Upper Freeport coal. As a workable ore it has been found only in the center of the Johnstown Basin. It has been worked in the hills about the city, on Hinckston Run, at the west base of Laurel Ridge, and on Mill Creek. At present it is of no importance. Flint clay occurs in the shale interval lying above the lower Mahon- ing 'sandstone. It lies close to the top of the lower sandstone bed at an interval ranging from 50 to 80 feet above the Upper Freeport coal. The position of this flint clay is shown in the section in the hill east of Johnstown (p. 116). Its characteristics are described later (pp. 115-117). The lower Mahoning sandstone outcrops in all the hills about Johnstown and has been quarried for building stone at many places. It is very massive, decidedly coarse grained, and micaceous. As a rule it ranges from 20 to 30 feet in thickness and is separated from the top of the Upper Freeport coal by 5 to 10 feet of dark-brown shale. Near South Fork the base of the Conemaugh is well shown in a recent cut on the Pennsylvania Railroad near Ehrenfeld. A hand- leveled section obtained opposite the station is as follows: Section of the base of Conemaugh formation at Ehrenfeld. Ft. in. Shale, weathering to clay 15 Shale, olive and drab, locally sandy 30 Coal 4-5 Shale 8 Shale, black 2 22 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Ft. Shales, blue and black 1 Coal , 2 Shales 15 Shale, blue, with alternating layers of fine-grained sandstone 20 Sandstone, massive 20 Upper Freeport coal. The Mahoning coal appears in this section, as in that south of Johnstown, in two benches at approximately the same distance above the top of the Upper Freeport coal. The lower bench is thick enough to be worked, though so far as known no coal has ever been obtained from it. The lower Mahoning sandstone is fairly massive, but hot so much so as in the hills near Johnstown. In the hills bordering Blacklick Creek, near Wehrum, the Mahoning coal measures about a foot in thickness and is closely underlain by old ore benches, indicating the formerly extensive workings on the Johnstown iron-ore bed. The underlying flint clay is present north, west, and southwest of Wehrum in a position similar with respect to the lower Mahoning sandstone to that of the flint clay occurring above the same sandstone near Johnstown, and is thus to be corre- lated with that stratum. The lower Mahoning sandstone is per- sistent where it appears above drainage level in the Blacklick Creek district, and is fairly massive. ALLEGHENY FORMATION. GENERAL CHARACTER. The Allegheny formation was originally known as the “Lower Productive Coal Measures. ” As may be inferred from that name, it is distinguished from the overlying formation by the presence of several workable coal beds. It is the most important formation in the Johnstown quadrangle, as in it are found all the workable coals of the area. The following section, compiled from the area about Johnstown and to the south, gives an idea of the general character of the formation in this quadrangle: Section of Allegheny formation about Johnstown and to the south. Ft. Coal, Upper Freeport (Coke Yard or E coal) 3 Shale 14 Shale with limestone concretions Shales, bluish Sandstone, laminated . . . Shales and sandy shales . Coal, 1 foot Bone, U inches Coal, 1 foot 7 inches. Bone, 1 inch Coal, 3J inches Lower Freeport (D or Limestone coal). in. 3 3 1 CARBONIFEROUS SYSTEM. 23 Ft. Limestone 3| Shale, blue 5 Shale, light drab, ferruginous 7 Shale, sandy Shale, blue black 4 Coal, Upper Kittanning (C / or Cement coal) 3f Shale 1 Limestone 5 Shale 3$ Shale, sandy Shale, black and brown Coal Shales, sandy Shales Coal Shale Interval, chiefly sandstone 20-25 Coal, 3 feet 8 J inches Bone or black shale, 3| inches. . Coal, 3J inches Bone, 1 inch Coal, 10 inches Fire clay Sandstone, gray, laminated 9 Sandstone, massive 40 Shale 2 Coal and bone (Clarion or A / coal) 3 Shale 10 Sandstone, blue, laminated 5 Pottsville. 280 to 285 Lower Kittanning (Mil- ler or B coal). 9 * A section of the base of the Allegheny in which both the Brook- ville and Clarion coals show is as follows: Section of lower part of Allegheny formation near A. J. Haws A Sons' brick plant , Coopersdale. Ft. in. Shale, dark.- 10 + Coal 1 0-4 Shale, black, with siliceous limestone concretions 10 Coal 51 Shale and bone 4 Coal 1 0-5 Shale and bone 0-10 Pottsville sandstone, massive. The thickness of the Allegheny ranges from 220 to 290 feet. At its top is the Upper Freeport coal; at its base the Brookville coal. The former occurs almost directly below the massive Mahoning sandstone; the latter rests directly on the top of the even more 24 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. massive Pottsville — circumstances which in this particular area are helpful in determining the boundaries of the formation. The more characteristic members of the Allegheny formation occurring in the Johnstown quadrangle are the following: Upper Freeport coal (E). Upper Freeport limestone member. Bolivar clay member. Butler sandstone member. Lower Freeport coal (D). Lower Freeport limestone member. Upper Kittanning coal (O'). Johnstown limestone member. Coals between the Upper Kittanning and Lower Kittanning coals. Lower Kittanning coal (B). Lower Kittanning clay member. Kittanning sandstone member. Clarion coal. B rook vi lie coal. A B C D E F Upper Freeport coal. Lower Freeport coal. Upper Kittanning coal. Middle Kittanr.ing coal. Lower Kittanning coal. Clarion coal. Brookville coal. Top of Pottsville formation. Figure 2.— Skeleton sections showing coals in the Allegheny formation. Vertical scale, 1 inch=100 feet. A, Compiled section near Coopersdale; B, compiled section on Peggvs and Clapboard runs: C, section north of South Fork; D, section south of South Fork; E, compiled section near southern border of quadrangle; F, section on Blacklick Creek. The position of the coals with reference to one another in the different districts is well shown in figure 2. U. S. GEOLOGICAL SURVEY BULLETIN 447 PLATE IV A. EXPOSURE OF LOWER FREEPORT COAL ON STONY CREEK, NEAR TROLLEY BRIDGE. The overlying sandstone is the Butler. The Lower Freeport limestone member shows below the coal. B. COUNTRY BANK OF THE BETTER CLASS ON THE UPPER KITTANNING COAL NEAR MINERAL POINT CARBONIFEROUS SYSTEM. 25 DETAILED DESCRIPTION. Upper Freeport coal. — The Upper Freeport coal lies at the top of the Allegheny formation, almost directly below the massive Mahoning sandstone member and from 220 to 290 feet above the top of the Pottsville formation, or, as it is locally called, the “Conglomerate Rock.” It is known in the Johnstown district as the Upper Free- port or E bed but most commonly as the Coke Yard coal. In the South Fork district it is called the Lemon or Four-foot coal. Its chemical and physical characteristics will be discussed in subsequent parts of this bulletin, as will be the case with the other workable coals. Upper Freeport limestone member. — In the region near South Fork the Upper Freeport limestone appears in the section. A short dis- tance east of Ehrenfeld it is well exposed in some recent excavations along the Pennsylvania Railroad, in which it ranges from 1 J to 3 feet in thickness. It is a gray limestone and very irregularly bedded. (See section, p. 65.) Bolivar clay member. — A flint clay lying a few feet below what is regarded as the Upper Freeport coal was seen at a few places in the valley of Mardis Run, near the northwestern edge of the quadrangle. This clay probably corresponds with the Bolivar fire clay of the region to the southwest. Two feet of clay was seen at one point on the outcrop, and the bed may possibly be thicker. Butler sandstone member. — In some places on Stony Creek a very massive sandstone 20 feet thick was observed lying directly over the Lower Freeport or D coal. (See PL IV, A.) This corresponds in position to the Butler or “ Upper Freeport” sandstone. It is very local in its development. Lower Freeport coal. — The Lower Freeport or D coal is known about Johnstown as the Limestone bed from a 2 to 3 foot bed of limestone occurring within a foot of its base. In position it ranges from 45 to 70 feet below the Upper Freeport coal. (See PL IV, A.) Lower Freeport limestone member. — The Lower Freeport limestone occurs either directly below or within a foot of the base of the Lower Freeport coal, the slight interval as a rule being filled with black shale. This limestone shows in Plate IY, A. Upper Kittanning ( C ') coal. — The next lower horizon of importance is the Upper Kittanning or C' coal, known near Johnstown as the Cement coal. It is an important coal near Johnstown and Windber, and in fact is one of the. most persistent and valuable coals in the quadrangle. It occurs from 80 to 105 feet below the Upper Freeport, though near South Fork this interval is less. Above the Upper Kittanning coal, near Johnstown and to the west on Dalton Run, some of the sections show one and some two small coals. These sections follow. 26 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Section of Upper Kittanning coal at mouth of Rolling Mill mine of Cambria Steel Com- pany , Johnstown, Pa. Ft. in. Sandstone, thin bedded 3 Coal 2-4 Sandstone, thin bedded and laminated 8 Shale 6 Coal, Upper Kittanning (O') 3 Shale 1 Limestone 44- Shale or fire clay 2-4 Section of Upper Kittanning (C / ) coal on Dalton Run. Shale. Ft. in. Coal 4 Shale 10 Coal 4 Shale 3 Coal 4 Shale or clay 24- Limestone bowlders. Johnstown limestone member . — About Johnstown the Upper Kittan- ning coal is underlain by a limestone which may prove suitable for the manufacture of cement. This cement bed is best developed along Stony Creek and may be seen to advantage in the cuts on the Balti- more and Ohio Railroad north of Kring, where it is 6 feet thick and is separated from the coal by 8 to 12 inches of shale. Along the spur track leading from the north end of the tunnel into the Valley Coal and Stone Company’s mines it is also conspicuous but is slightly thinner. An analysis of this cement rock is given on page 128. It is shown in Plate VII, A (p. 48). Coals between the Upper and Lower Kittanning coals . — In several of the sections south of Johnstown a coal bed occurs from 17J to 20 feet below the base of the Upper Kittanning coal. This coal is very thin, in most places measuring less than 6 inches. It may be seen in the bluffs near the Citizens Eighth Ward mine and in the cut on the Baltimore and Ohio Kailroad north of Kring. At the latter place another coal 7\ inches thick appears in the section 13 feet below the upper thin coal and about 31 feet below the base of the Upper Kittan- ning bed. What is probably the upper of these two coals appears in many of the drill records from the Wiimore Basin, and both are per- sistent in the section along the main line of the Pennsylvania Railroad east of East Conemaugh. In the latter region, however, the lower coal, which it is thought must be the representative of the Middle Kittanning (C) coal, lies 45 to 50 feet below the base of the Upper Kittanning — a distance greater than at Kring. Near the brick plant of A. J. Haws & Sons (Limited), at Coopersdale, what is tentatively regarded as the Middle Kittanning occurs 25 feet above the Lower Kittanning bed. CARBONIFEROUS SYSTEM. 27 Lower Kittanning coal. — The next lower coal — the Lower Kittanning, Miller, White Ash, or B coal — is the most persistent and valuable bed in the area. It usually lies approximately 145 to 200 feet below the Upper Freeport coal and from about 65 to 100 feet above the top of the Pottsville. Lower Kittanning clay member. — The Lower Kittanning clay is the most valuable plastic clay in the area. It usually underlies the lower bench of the Lower Kittanning coal, from which it may be separated by a few inches of shale. In the absence of the lower bench of coal it sometimes occurs below the main coal itself, being separated from it by 3 to 4 inches of bone or shale. (See, further, pp. 117-118, 123.) Kittanning sandstone member. — On the Baltimore and Ohio Rail- road, between Foustwell and the mouth of Paint Creek, on the west flank of the Ebensburg anticline, the Pottsville and the beds below the Lower Kittanning coal are well exposed. Near the water tank and culvert nearly a mile east of the bridge over Stony Creek the following section was measured: Section of the lower part of the Allegheny formation , east of Foustwell. Base of Lower Kittanning coal. Ft. In. Fire clay 4 8 Sandstone, laminated 9 8 Sandstone, massive 40 Shale 2 Coal 6 Shale, black 6 Coal ‘ 2 7 Shale 10 Sandstone, blue, laminated s 5 Pottsville sandstone, massive. Brookville and Clarion coals. — Between the Lower Kittanning coal and the top of the Pottsville formation are found either one or two coals. The coal noted in the preceding section is one of these, possi- bly the upper or Clarion bed; where the section was taken it is of workable thickness. Both coals appear at the roadside near A. J. Haws & Sons’ brick plant, west of Coopersdale. (For section, see p. 23.) The lower coal, consisting of two benches, is the Brook- ville; the higher is regarded as the Clarion. Representatives of these lower coals are found near Twin Rocks. POTTSVILLE FORMATION. The Pottsville, where most plainly developed in the Johnstown quadrangle, consists of three members — an upper and a lower sand- stone, known respectively as the Homewood and Connoquenessing sandstone members, and an intervening shale (containing a coal bed), known as the Mercer shale member. With these is associated an important flint clay. 28 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. A section of the Pottsville along Stonj- Creek, in part off the southern edge of the quadrangle, is as follows: Section of Pottsville formation in and near Johnstown quadrangle. Feet. Sandstone, massive (Homewood) 65-90 Shale, black, and clay (Mercer) 11 Sandstone, massive (Connoquenessing) 95-105 This gives a total thickness to the Pottsville of about 170 feet. Between South Fork and Mineral Point the thickness of the Home- wood member, where it could best be observed, is only about 35 feet, indicating a thinning to the east; the thickness of the whole forma- tion, however, remains at about 170 feet. In the South Fork district the Mercer interval contains a valuable flint clay. The Pottsville is not always devoid of coal, as the section green above might indicate. South of Kring the Mercer contains a coal bed whose section is given on page 61. At the B. H. Campbell shale quarry, on the Mercer (p. 119), coal is also present. The sandstones of the Pottsville are massive and coarse grained but rarely conglomeratic. They make very large sandstone debris, and the country underlain by the Pottsville is usually wilderness. MISSISSIPPI AN SERIES. MATCH CHUNK SHALE. Evidences of an unconformity at the top of the Mauch Chunk are to be seen in the Johnstown quadrangle. The Mauch Chunk is well exposed along the flanks of the Ebensburg anticlinal axis on Stony Creek, near the bridge at the mouth of Paint Creek, and also south of the quadrangle. It is also well shown at the viaduct along the flanks of the Viaduct or Ebensburg anticline (PI. V, A ), farther west in the gorge of Conemaugh River, and on the sides of Laurel Ridge, where it is brought above drainage level by the Laurel Ridge anti- cline. The upper 50 feet of this formation is exposed in the valley of South Branch of Blacklick Creek, near Twin Rocks. A section of the upper part of the formation, obtained on Stony Creek about a mile above the mouth of Paint Creek, is as follows: Section of upper two members of Mauch Chunk shale near mouth of Paint Creek . Ft. in. Shales, red 6-21 Sandstone, heavy 10 8 Shale, red 20 Sandstone, vivid green , 3 Shales, red and green 13-15 Shale, green 1 Shale, blue-green, sandy 5 4 Sandstone, green, usually laminated and cross bedded 44-f U. S. GEOLOGICAL SURVEY BULLETIN 447 PLATE V A. TYPICAL EXPOSURE OF MAUCH CHUNK SHALE AT THE VIADUCT BETWEEN SOUTH FORK AND MINERAL POINT. Note the alternating thin layers of sandstone and shale and the vertical jointing. B. SHALE QUARRY OF B. H. CAMPBELL AT THE MERCER HORIZON NORTH OF SHERIDAN. The rounded bowlders in the foreground are probably of Pleistocene age. U. S. GEOLOGICAL SURVEY BULLETIN 447 PLATE VI A. DETAILED STRUCTURE OF LOYALHANNA LIMESTONE AT THE TOP OF THE POCONO FORMATION, EAST OF MINERAL POINT. Weathering has brought out the cross-bedding of the rock. B. LOYALHANNA LIMESTONE, TOP MEMBER OF POCONO FORMATION, AT SUMMIT OF EBENS- BURG (VIADUCT) ANTICLINE, MINERAL POINT. DEVONIAN SYSTEM. 29 Near the viaduct the lower green laminated and cross-bedded sand- stone member given in the sectiori appears, dividing, as it were, the Mauch Chunk into an upper and lower shaly member. It may rep- resent the Greenbrier limestone in this region. This sandstone at the viaduct was measured in its entirety and was found to be 42 feet thick. The lower shale division at the viaduct is 40 feet, giving to the members of the Mauch Chunk the following thicknesses: Section of Mauch Chunk shale at the viaduct. Feet. Upper shaly member 60-75 Sandstone 44+ Lower shale member 40 Thus the Mauch Chunk in this quadrangle may be considered approximately 160 feet thick. POCONO FORMATION. The upper part of the Pocono shows in the bed of Conemaugh River between the viaduct and Mineral Point. It is made up of the Loyalhanna limestone member, about 45 feet of which is here exposed. (See PI. VI, A and B.) The entire formation is above drainage level in the gorge of Conemaugh River west of Johnstown. It is brought above water level by the Laurel Ridge anticline and covers part of the ridge both south and north of the river. Though it is not exposed so as to be measured in detail, the barometer indicated from the top of the red Catskill beds to the red shales of the Mauch Chunk over- lying the Loyalhanna limestone a thickness of 1,085 feet, which it is believed closely approximates the thickness of this formation in the region. This is slightly greater than the figures obtained by Charles Butts and the writer® on the Allegheny Front. There is no reason to suppose that the Pocono here differs much from that on the Alle- gheny Mountain east of Bennington. DEVONIAN SYSTEM. CATSKILL FORMATION. But 400 feet of Devonian rocks are exposed in the Johnstown quadrangle, and these occur at the top of the Catskill, in the gorge of Conemaugh River where it is crossed by the Laurel Ridge anticlinal axis. The Catskill beds are prevailingly red and green shales and red sandstones and color the soil a distinct red. The upper part of the formation was measured by the writer as follows: a Ebensburg folio (No. 133), Geol. Atlas U. S., U. S. Geol. Survey, 1905, p. 3. 30 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Section of upper portion of CatsJcill formation on Conemaugh River. Feet. Sandstone, chocolate and reddish 45 Shale, red 20 Sandstone, chocolate-colored 5 Shales, chocolate and vivid green 40+ STRUCTURE. MODE OF REPRESENTATION. The inclination of the beds to a horizontal plane, or the dip, as it is commonly called, is measured in the field by means of a cli- nometer where the inclination is great enough to permit it. In but few localities in the Johnstown quadrangle, however, are the dips sufficient to allow this mode of measurement. Where it is not appli- cable continuous road sections are run and the beds are correlated from hillside to hillside. When the elevation above mean sea level of a sandstone, coal, or limestone on one hill and its elevation a mile or so away have been found, the rise or fall of this particular bed in feet per mile is at once obtained. By connecting points of equal elevation on any selected bed the contour lines for that bed are drawn. On the map, Plate I, the contour interval is 50 feet and all points on the plane selected (the base of the Lower Kittanning or B coal) that are multiples of 50 are connected by light-brown lines. The base of the Lower Kittanning coal was selected as the bed on which to draw structure contours in the Johnstown quadrangle because this is commercially the most important coal and the most persistent. Moreover, its relations to the beds both above and below it are fairly well known. To draw contours on the bed where it is above drainage level and is worked is easy, for it is necessary simply to obtain its elevation from point to point where it outcrops and then to connecting points of equal elevation. But where the coal fails to appear above drain- age level other means of determining its elevation have to be em- ployed, and its distance below other known beds that do appear must be used as a basis for calculation, it being assumed, of course, that this distance is constant within the areas where this method is employed. Conversely, where the dips are so great as to carry the horizon of the coal above the hilltops its interval above known beds must be used. When the latter two methods are employed in contouring great precision is not obtainable, as intervals are sub- ject to variation in any region and are known to vary greatly within comparatively short distances in the Johnstown quadrangle. Fur- thermore, most of the elevations in this work are obtained by means of the aneroid barometer, which, as is well known, is liable to sudden variations and has to be constantly checked against spirit- leveled elevations. STRUCTURE. 31 The structure contours not only show the generalized surface formed by the Lower Kittanning coal but less precisely the lay of the underlying and overlying beds. The contour interval chosen is 50 feet and the limit of error may be considered a contour interval, but where the beds vary in thickness it may be more than this. This mode of representing the structure makes it possible to estimate approximately the elevation of the top of the Lower Kittanning coal where it is below the surface at a given point, and hence to find its depth below the surface at that point ; furthermore, if the intervals of other coals either above or below the Lower Kittanning are known, their depth at any particular point may be readily computed. STRUCTURE IN THE JOHNSTOWN QUADRANGLE. GENERAL STATEMENT. The beds described under the heading “ Stratigraphy” (pp. 14-30) are involved in a series of parallel folds having a general northeast- southwest trend and extending completely across the area in a series Figure 3.— Sketch showing (a) the great irregularity in detail of the structure in some parts of the Johns- town quadrangle and (6) the marked regularity in detail in other parts. In 6 the 5-foot contour lines are omitted to avoid crowding, but were they inserted the regularity would appear almost as pronounced. of waves from the southeast to the northwest part of the quadrangle. The structure as worked out differs in some particulars from that described by the Second Survey of Pennsylvania, the most notable difference perhaps being in the offset of the Johnstown Basin to the 32 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. east near Johnstown (PL I). In the map of the Second Survey the axis of the Johnstown syncline or basin is represented as being west of the South Fork of Bens Creek; it is believed that it really lies farther to the east. Viewed broadly, the structure is very regular in the Johnstown quadrangle, as will be seen from the structural contour map (PL I). In detail it may be decidedly irregular. (See fig. 3.) The structural features in the Johnstown quadrangle, beginning in the southeast corner and proceeding to the northwest, are — Wilmore syncline. Viaduct or Ebensburg anticline. Johnstown syncline. Laurel Ridge anticline. Westover or Barnesboro syncline. In the reports of the Second Geological Survey of Pennsylvania the Wilmore and Johnstown basins were designated subbasins and were considered to constitute part of the first bituminous coal basin. The Viaduct anticline was called a subaxis and the Laurel Ridge anticline was designated the first grand axis of the bituminous coal regions.® DTnvilliers 6 somewhat changed the usage, .as he speaks of the first and second basins, referring to the Wilmore and Johns- town basins, respectively. The terms syncline and basin or trough are of course synonymous, as are also the terms anticline and arch. DETAILED DESCRIPTION. Wilmore syncline . — The Wilmore Basin or syncline is so called from the town of Wilmore, situated on the Pennsylvania Railroad a short distance east of Summerhill, in the Ebensburg quadrangle. It is a comparatively long and narrow synclinal trough parallel with and west of the Allegheny Front. The position of the axis of the basin is definitely fixed near the town of Wilmore by the opposing dips of the rocks along the old track of the Pennsylvania Railroad. As indi- cated on Plate I, the axis enters the Johnstown quadrangle northeast of the old reservoir site on South Fork of Conemaugh River and con- tinues southeast, passing near the town of Elton. It leaves the quadrangle in a line almost coincident with the South Fork branch of the Pennsylvania Railroad. On the southeast side of this axis the beds dip northwest, and on the northwest side the beds dip southeast. In the quadrangle all the beds along the axis dip northeast, as the axis plunges in that direction. The rise of the beds to the southwest is rapid, amounting to 900 feet in a distance of 16 or 17 miles, so that the Lower Kittanning coal, which is between 800 and 900 feet above the sea and hence far below drainage level in the center of the basin, a Second Geol. Survey Pennsylvania, Rept. H2, pp. xxix, 25, 26. i> Summary Final Rept. Geol. Survey Pennsylvania, 1895, p. 2219. I STRUCTURE. 33 outcrops at an elevation of about 1,700 feet at the mines about Windber. Viaduct anticline . — The Viaduct or Ebensburg anticline is the next structural feature to the west. Its axis has a general northeast- southwest direction, but swerves slightly to the southeast and then again to the southwest in the part of the quadrangle south of Cone- maugh River. This offset, however, is not at all marked. The Lower Kittanning coal and associated beds, so deeply buried in the center of the Wilmore Basin, rise rapidly and with great regu- larity to the west and outcrop in the valley of Conemaugh River at South Fork. From its deepest point in the Wilmore syncline the coal rises more than 1,000 feet to its highest point on the summit of the Viaduct or Ebensburg anticline. The lowest bed brought above drainage level by this rise is the top member of the Pocono forma- tion (the Loyalhanna limestone member), which outcrops along the summit of the arch, between the viaduct and Mineral Point. (See PI. VI, A and B.) Johnstown Basin . — The Johnstown Basin or syncline, which is the next structural feature to the west, comprises the area between the Viaduct and Laurel Ridge anticlinal axes. It is really made up of two basins in this quadrangle, one in Cambria and one in Somerset County. It has a general northeast-southwest course but is sharply offset to the east in the vicinity of Johnstown. (See PL I.) The axis in Somerset County trends in the usual northeast-southwest course. The dip of the beds on the east side of the basin is compara- tively gentle, the fall being approximately 900 feet in 9 miles, or at the rate of 100 feet per mile from the summit of the Viaduct anti- cline at the viaduct to the deepest part of the basin north of Cone- maugh River. In the southern part of the quadrangle the correspond- ing drop is only 700 feet. On the west side of the basin the rise of the beds to the Laurel Ridge axis is sharp — between 2,000 and 2,100 feet in a distance of 9 miles along Conemaugh River — producing the maxi- mum dips in the quadrangle. In addition to their inclination from the northwest and southeast to the center of the basin, the beds north of Conemaugh River dip gently to the northeast. The Johnstown synclinal axis and the Ebensburg anticlinal axis approach each other near the northeast corner of the quadrangle. Laurel Ridge anticline . — The Laurel Ridge anticline is the major structural feature in the Johnstown quadrangle, and, as stated on page 32, it is the “ first grand axis” as described by the Second Geological Survey of Pennsylvania. It crosses Conemaugh River about midway between Conemaugh Furnace and Coopersdale and passes to the northeast, crossing South Branch of Blacklick Creek a little over a mile southeast of Twin Rocks. Where the axis of the 69516°— Bull. 447—11 3 34 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. fold crosses the valley of Conemaugh River the lowest beds in the quadrangle — the red shales and sandstones of the Catskill formation, aggregating 400 feet or more above drainage level — are exposed. The fold pitches sharply to the northeast, and the Pocono formation, which caps the hills where the axis crosses Conemaugh River, is below drainage level where it crosses South Branch of Blacklick Creek near Twin Rocks, dropping in this distance at least 1,000 feet. As stated in the description of the Johnstown Basin, the beds along the eastern flank of the Laurel Ridge anticline rise between 2,000 and 2,100 feet in a distance of 9 miles. The fall in the beds west of the anticlinal axis to the Barnesboro or Westover Basin is at about the same rate. The anticline is therefore symmetrical. No beds of coal are present at the summit of the ridge and none occur below its surface until Blacklick Creek is approached. The coals have, so to speak, been carried out into the air by the rise in the beds on either side of the anticlinal axis. Barnesboro or Westover syncline . — The basin west of the Laurel Ridge anticline is termed the Westover Basin in the Pennsylvania Geological Survey reports. More recently it has been called the Barnesboro Basin by members of the United States Geological Survey. 0 The axis of the basin enters the Johnstown quadrangle near the line between Cambria and Indiana counties, passes through or very near Wehrum, and leaves the quadrangle as indicated on Plate I. From the axis of this basin the beds rise gently to the axis of the Nolo anticline, which just cuts the northwest corner of the quadrangle. Minor structures . — Besides the principal folds, there are many minor folds in the rocks of the quadrangle. A small arch or anti- cline is exposed along Little Conemaugh River about a mile east of Conemaugh station. From this point westward to the Johnstown station there are many minor fluctuations, all exposed along the main line of the Pennsylvania Railroad. Between Millville and Coopers- dale there is a distinct anticline. Thus it appears that the main broad Johnstown syncline has been subjected to many minor plica- tions. It has been thought by some mining men that to these lesser folds about Franklin and along Clapboard Run is due the so-called faulting which the coal exhibits in this region. The erratic behavior of the Lower Kittanning coal in this locality may possibly be due in part to this cause, but the irregularities seen by the writer are not faults as this term is used in the geologic sense, but are rather broad rolls which seem to have squeezed out the coal. In some places the conditions during sedimentation were such that coal was not depos- ited or, if deposited, was afterward removed. a Campbell, M. R., and Clapp, F. G., in an unpublished manuscript relating to the Barnesboro quad- rangle, which lies north of the Johnstown quadrangle. COAL. 35 MINERAL RESOURCES. INTRODUCTION. The mineral resources of the Johnstown quadrangle are coal, flint and plastic clay, shales, limestone and cement material, building stone, glass sand, and iron ore. Because of the great importance of coal and clay they will be treated (1) in a broad way for the sake of the general reader who may be interested in the area as a whole but not in any particular portion of it, and (2) in detail by districts. The remaining resources— limestone and cement material, building stone, glass sand, and iron ore — will be treated as a whole, as their description by districts would involve needless repetition. COAL. GENERAL DESCRIPTION. UPPER FREEPORT COAL. The highest important coal in the Johnstown quadrangle is known as the Upper Freeport. It is used as a domestic and steam fuel about Johnstown and South Fork and supplies some of the brick plants at Johnstown. It gives satisfactory results, particularly when used in locomotives. It is not coked in this quadrangle, though at Cresson, Gallitzin, and Bennington it gives satisfactory results in beehive ovens. In the by-product ovens of the Cambria Steel Company at Franklin, near Johnstown, it was found to be unsuitable owing to expansion, which quickly ruined the ovens and made it very difficult to force out the charge after it was coked. The analyses of this coal as given on page 40 show it to be a high-carbon coal with very low moisture content. The ash, especially in the Johnstown Basin, is high; its sulphur content, ranging from 2 to 2 \ per cent, is also rather high. LOWER FREEPORT COAL. The Lower Freeport or D coal is of workable thickness about Johns- town, and, though not exploited at present, it will probably become one of the important coals of the Johnstown district. Its percentage of carbon is high. UPPER KITTANNING (c') COAL. The Upper Kittanning or C' coal is one of the most valuable beds about Johnstown and its suburbs, where it is known as the Cement bed. To the south, about Windber, prospecting has shown it to be even thicker than about Johnstown. As a steaming coal it is probably equal if not superior to any other coal in the Johnstown 36 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Basin, and the recent demand for it has been greater than the supply. The six analyses (p. 40) show a high-carbon coal with correspondingly low volatile matter. The moisture is low, but the ash and sulphur are rather high. The coal mined from this bed at Franklin mine No. 1 of the Cambria Steel Company is washed and coked at the Franklin plant. It makes a coke of good grade, but owing to its low volatile matter it is not considered so well adapted for beehive ovens as some of the richer gas coals of the districts farther west. In view of the cost of shipping coke from the region about Connellsville and Pittsburg, it is cheaper to wash and coke this coal on the ground. The coal is worked also in a small way near South Fork. LOWER KITTANNING (MILLER) COAL. CHARACTER AND IMPORTANCE. The next lower coal of importance in this area is the Lower Kittan- ning or B coal, also widely known as the Miller seam. This is the most persistent of the valuable coals of the area. From the analyses on pages 40-42 it will be seen that its fixed carbon ranges from 68 per cent in sample No. 24, collected at Welirum, Indiana County, to more than 78 per cent in samples collected at South Fork. Its volatile matter ranges from 14 to 19 per cent. Its moisture is low; only a few analyses show more than 3 per cent and in none of them does it exceed 4 per cent. The ash and sulphur exhibit considerable varia- tion, as might naturally be expected in view of the wide extent of the territory from which the samples were collected. The samples from South Fork have the lowest content both in sulphur and ash and show the excellent character of the Lower Kittanning bed in this part of the Wilmore Basin. As a steam coal it ranks among the very best in western Pennsylvania, the coal mined about South Fork probably equaling any other ste^am coal in this part of the State. As bearing on this point the following table has been prepared, showing its posi- tion among the 120-odd coals tested at the fuel-testing plant of the United States Geological Survey at St. Louis, Mo., since the summer of 1904. a The column recording the number of pounds of water evaporated by 1 pound of dry coal from and at a temperature of 212° F. gives the comparative results of the coals tested so far as these relate to their commercial value. a Bull. U. S. Geol. Survey No. 261, 1905, and No. 290, 1906. COAL. 37 Chemical composition and steaming values of typical Appalachian coals. Location. Num- ber of tests made. Aw Mois- ture. erage chem Volatile matter. lical com Fixed carbon. positio Ash. in. Sul- phur. Average pounds of water evap- orated from and at 212° F. per pound of dry coal. Page, Fayette County, W. Va 2 4.06 30. 35 61.54 4.05 0.90 10. 545 Do 1 2. 85 30. 13 64. 78 2. 24 1.06 10. 52 McDonald, Fayette County, W. Va 2 2.75 20. 59 70.05 6. 61 .98 10.36 Big Black Mountain, Harlan County, Ky 2 5. 06 34. 77 56. 31 3. 86 .56 10. 26 Rush Run, Fayette County, W.Va 2 2. 12 21.91 70. 73 5. 24 .67 10. 195 Ehrenfeld, Cambria County, Pa 5 2. 38 16. 53 74. 47 6.62 .95 10. 186 Winifrede, Kanawha County. W.Va 4 3. 79 35. 33 55. 76 5. 12 1.11 10. 16 Acme, Kanawha County, W. Va 4 2. 93 32. 66 57. 64 6. 77 1. 23 10. 115 Powellton, Fayette County, W. Va 1 3. 42 31. 11 59. 47 6. 00 .82 10.09 Near Bretz,. Preston County, W.Va 3 4. 20 28.05 60. 86 6. 89 1.28 10. 07 The results of tests on the Ehrenfeld samples, although showing a range of 9.75 to 10.42 pounds of water evaporated per pound of dry coal used, are yet, when averaged, among the very best obtained at the testing plant. Each sample submitted to the steaming test was analyzed, and the accompanying analyses represent averages of the total number made, as do the figures representing the efficiency of the coals as steam producers. It is of interest to note that the Ehrenfeld coal contains the largest percentage of fixed carbon and the lowest amount of volatile matter of all the samples. Other samples of the Lower Kittanning coal tested by the United States fuel-testing plant from January 1, 1906, to June 30, 1907, include a few from in or near this quadrangle. The results of these tests are given below, together with the analyses of the samples tested. For comparison the results (given above) from the Ehren- feld coal are repeated. Chemical composition and steaming values of typical Appalachian coals. Average chemical composition. Average pounds of water evap- orated from and at 212° F. per pound of dry coal. Location. Num- ber of tests made. Mois- ture. Volatile matter. Fixed carbon. Ash. Sul- phur. Wehrum, Blacklick Creek district, Indiana Countv o 2 2.17 17.5.8 69. 81 10.45 4. 62 9.19 Lloydell, Cambria County (southeast of quadrangle) b 2 5.00 19.05 66. 78 9. 18 1.53 c 9. 52 Near Seward, Conemaugh Furnace district, Westmoreland County d 2 3. 15 20.55 67. 75 8.56 1.79 c 8. 90 Ehrenfeld,- South Fork district, Cambria County 5 2. 38 16.53 74. 47 6.62 .95 10. 186 a Bull. U. S. Geol. Survey No. 332, 1908, pp. 201, 202. b Idem, pp. 210, 211. Lloydell is on the east flank of the Wilmore Basin and on the quadrangle to the east, c Test made on briquets from the coal.' d Bull. U. S. Geol. Survey No. 332, 1908, pp. 216, 217. 38 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. The figures obtained in the last column give comparative commer- cial values which show the high grade of the Lower Kittanning coal as coal or in briquet form in and near the quadrangle. It is of inter- est to see how the analysis and steaming values of the coal collected at Lloydell on the east flank of the Wilmore Basin compare with the results obtained near Seward in the area to the west. For the details of the conditions governing these steaming tests the reader is referred to Bulletin 332. COKING TESTS. The Lower Kittanning (Miller) coal is coked, but it does not rank so high as a coking coal as it does as a steam producer. Tests on samples yielded the following results: Coking tests on Lower Kittanning coal in Johnstown quadrangle. L 2. 3. 4. 5. Duration of test hours. . Size as used 51 (a) 10.000 5,223 52. 23 1,600 16.00 68. 23 61 (a) 9,750 5,779 59. 27 262 2.69 61.96 54 (*) 12,460 8,144 65. 36 332 2. 66 68.02 68 (a) 13,070 8,129 62. 20 420 3. 21 65. 41 78 (a) 11,760 7,350 62. 50 529 4. 50 67.00 Coal charged pounds. . Coke produced {^’cent Breeze produced {percent ' ' Total yield per cent. . a Finely crushed. & Run of mine. Analyses of Lower Kittanning coal and of coke made from it. 1. 2. 3. 4. 5. Coal. Coke. Coal. Coke. Coal. Coke. Coal. Coke. Coal. Coke. Moisture 3.32 0.91 7.19 0. 56 4.53 0. 57 3. 91 0. 30 6. 30 0. 51 Volatile matter 15. 56 2.16 17. 86 .32 18. 56 .55 16. 35 .28 17. 04 .58 Fixed carbon 74.29 88. 99 69.57 91.10 70. 63 90.23 68.30 84. 95 69.58 89.85 Ash 6.83 7.94 5. 38 8. 02 6. 28 8. 65 11.44 14. 47 7.08 9.06 Sulphur 1.12 .91 1.63 1.46 1.85 1.54 2. 78 2.31 1.34 1.11 1. Raw bituminous coal from mine No. 3, Pennsylvania Coal and Coke Company, Ehrenfeld, collected under supervision of J. S. Burrows. Bull. U. S. Geol. Survey No. 290, 1906, p. 181. 2 and 3. Washed run-of-mine coal from Wehrum, collected under supervision of John W. Groves. Bull. U. S. Geol. Survey No. 332, 1908, p. 203. 4. Raw run-of-mine coal from a mine 1| miles east of Seward, collected under supervision of John W. Groves. Bull. U. S. Geol. Survey No. 332, 1908, p. 218. 5. Washed run-of-mine coal from same locality as No. 4. The results obtained from the coking tests were as follows : The coke from Lower Kittanning coal collected at Ehrenfeld (No. 1) was soft and dense, dull gray in color, with a heavy black butt. It broke in large and small chunks and was difficult to burn. The cell structure was small. The coke from the first test (No. 2) on the Wehrum sample was soft and dense and dull gray in color. The high content in sulphur is worthy of note. The coke from the second test (No. 3) on the Wehrum COAL. 39 sample was light gray or silvery in color and much better than the coke from the finely crushed coal (No. 2). It also was high in sul- phur. The coke from the first test (No. 4) on the sample collected 1 \ miles east of Seward was light gray or silvery in color and was soft and dense, with high ash and sulphur. The coke from the second test (No. 5) was gray in color; washing produced no change in its physical appearance though it reduced the ash and sulphur slightly. As in the test No. 4, the coke was soft and dense. It may be added that the yield of coke in all the above tests is high. The coal mined at Franklin (analysis 11, p. 40) is coked by the Cam- bria Steel Company in by-product ovens for use in the company’s plant near Johnstown and gives satisfactory results. The coal is washed before coking, thereby adding to the cost, but even with this additional expense it is found cheaper to coke this coal on the ground than to buy coke of better quality from the Connellsville region. Tests have been made by the Cambria Steel Company with the coal mined from this bed about Ehrenfeld, and the resulting coke proved well adapted to metallurgical purposes. The yield also was satisfac- tory. The coal mined at Nanty Glo from this bed has been tested in beehive ovens at Gallitzin. It produced coke of good structure but of a rather dull appearance. As w~as to be expected, an insuffi- cient amount of sulphur was volatilized. At Bennington this coal, like the Upper Freeport, shows a higher content in volatile matter than it does about South Fork and Johnstown. The Lackawanna Coal and Coke Company has experimented with it about Wehrum, but the washeries have been shut down and the results of the coking tests were not learned. The results of Survey tests have already been given (p. 38). The Vinton Colliery Company has erected a by- product plant at Vintondale, and in 1907 a considerable part of the coal mined from colliery No. 6 was coked. MISCELLANEOUS TESTS. Other tests have been made on the Lower Kittanning coal, such as producer-gas tests, washing tests, cupola tests, and briquetting tests. The details connected with these are given where this coal is considered in the different districts (pp. 71-76, 83-88, 98-100). LOWER ALLEGHENY COALS. The coals below the Lower Kittanning have not been extensively developed in this area. At South Fork a bed lying about 60 feet below the Miller coal and known locally as the Dirty A or Six-foot seam has been opened. It is possible that this corresponds to the Brookville (A) coal of the Allegheny Valley. It has a composition indicated by analysis 36 on pages 41-42, and from the high ash and 40 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. sulphur content, aggregating more than 15 per cent, deserves the name which is often applied to it. In other respects the analysis corresponds with those of other coals of the area, being relatively high in fixed carbon and low in volatile matter. COMPOSITION OF THE COALS. The coals of the Johnstown quadrangle belong to the soft, lustrous, semibituminous variety. They are best adapted for steaming and .domestic purposes, but some of them make also an excellent coke. They are classed as smokeless coals because of their small content of volatile hydrocarbons. They are uniformly high in carbon and contain small amounts of volatile matter and moisture. Their ash and sulphur contents are variable but in general terms high compared with other Appalachian coals — for instance, those of West Virginia and eastern Kentucky. Some analyses of samples collected accord- ing to present Survey methods are listed below. Analyses of coal samples from Johnstown quadrangle , Pennsylvania. a Upper Freeport (E). Lower Free- port (D). Upper Kittanning (C'). 1. 2 . 3. 4. 5. ' 6 . 4 8. 9. io: Sample as received: Moisture 2. 65 2.82 3. 04 4.73 2. 81 1. 67 2. 60 1. 94 2.93 3. 51 Volatile matter 14. 86 15. 61 16. 27 13. 78 15. 07 18. 52 14. 10 15. 81 13. 47 17.16 Fixed carbon 72. 38 70.32 73. 47 72. 27 72. 64 69. 14 72.05 70. 77 74.06 69.04 Ash 10.11 11. 25 7.22 9. 22 9. 48 10.67 11. 25 11. 48 9. 54 10.29 Sulphur 2.06 2.42 2. 18 1. 09 1. 92 3. 46 2.79 3.73 1. 88 2. 01 Loss of moisture on air drying. . 2. 00 2. 10 2. 50 4.00 2. 20 1. 00 2. 00 1.20 2.20 2. 30 Air-dried sample: Moisture .66 .74 .55 .76 .62 .68 .61 . 75 . 75 1. 24 Volatile matter 15. 16 15-94 16. 69 14.35 15. 41 18. 71 14. 39 16.00 13. 77 17.56 Fixed carbon 73. 86 71. 83 75.35 75. 28 74.28 69. 84 73.52 71.63 75. 73 70. 67 Ash 10. 32 11. 49 7.41 9. 61 9. 69 10. 77 11. 48 11.62 9.75 10. 53 Sulphur 2. 10 2. 47 2. 24 1. 14 1.96 3. 49 2. 85 3. 78 1. 92 2.06 Lower Kittanning (B). 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. Sample as received: . ("Moisture 2.70 2.03 2. 81 1.78 2. 21 2. 24 2.63 2.79 3. 12 3. 07 g 1 Volatile matter 15. 64 14.47 14.66 15. 19 14.32 15.70 17.85 17. 76 17. 89 17. 64 *-• ) Fixed carbon 74.03 75. 31 75.75 73. 25 78. 16 78. 37 73. 24 73. 20 70.85 72. 85 ^ [(Ash 7. 63 8. 19 6.78 9.78 5. 31 3.69 6.28 6.25 8. 14 6. 44 f\ Sulphur 1.93 2. 26 1.33 4.50 .47 .77 1. 49 1.88 2. 74 1.38 . Hydrogen 4. 14 4. 16 ^ < Carbon 79.97 77. 10 ^ Nitrogen 1. 26 1. 41 [Oxygen . . . 4. 18 3.05 Calorific value determined: Calories 7,823 7,612 British thermal units 14,081 13, 702 Loss of moisture on air drying. . 1.80 1. 40 1.90 1. 10 1.60 1.60 2.00 2. 10 2.50 2.50 a All analyses given in this paper, unless otherwise stated, were made at the fuel-testing plant of the United States Geological Survey at St. Louis, Mo.; J. A. Holmes in charge; F. M. Stanton, chemist. COAL, 41 Analyses of coal samples from Johnstown quadrangle , Pennsylvania — Continued. Lower Kittanning (B)— Continued. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. Air-dried sample: f Moisture ... . 0. 91 0.64 0.93 0.69 0. 62 0.65 0.64 0. 71 0.64 0.58 Volatile matter 15. 93 14. 67 14. 94 15. 36 14. 55 15.95 18.21 18. 14 18. 35 18.09 »h I Fixed carbon 75. 39 76. 38 77.22 74. 06 79.43 79. 65 74. 74 74. 77 72. 67 74. 72 ^ (./Ash. 7. 77 8. 31 6. 91 9. 89 5. 40 3. 75 6. 41 6. 38 8.34 6. 61 HSulphur 1. 97 2.29 1. 36 4. 55 .48 .78 1.52 1.92 2. 81 1. 42 . (Hydrogen 4. 04 4.08 S J Carbon 81. 10 77.95 (Nitrogen 1. 27 1. 43 [Oxygen 2. 99 2. 10 Calorific value determined: Calories 7,934 14,281 7,697 13,854 British thermal units ! Lower Kittanning (B)— Continued. 21. 22. 23. 24. 25. 26, 27. 28. Sample as received: f Moisture 2. 80 3.45 2.59 3. 83 2. 84 3.13 2.57 3.49 * 1 Volatile matter 17.30 18. 82 18.91 19. 03 17.47 17.61 18. 09 16.12 1 Fixed carbon 73.28 71. 18 70. 33 67.89 71.42 69. 45 69. 01 74.68 ^ [/Ash 6. 62 6. 55 8. 17 9. 25 8.27 9. 81 10. 33 5.71 n Sulphur 2. 46 2. 01 4.04 4. 57 3.11 3. 77 3.97 .95 . Hydrogen 4. 62 4.43 J Carbon 76.41 75. 89 P Nitrogen. . 1. 14 1. 16 [Oxygen 4.25 4.22 Calorific value determined— Calories 7,821 14,079 7, 664 13,795 7,618 British thermal units . 13,712 Loss of moisture on air drying 2. 00 3.00 2.00 3.30 2. 40 2. 80 2. 10 2. 80 Air-dried sample: . ("Moisture .82 .46 .60 .55 .45 .34 .48 .71 g 1 Volatile matter 17.65 19. 40 19. 30 19.68 17. 90 18. 12 18.48 16.58 s-d Fixed carbon 74. 77 73.38 71.77 70. 20 73. 18 71.45 70. 49 76. 83 ^ [/Ash 6. 76 6. 76 8.33 9. 57 8. 47 10. 09 10. 55 5. 88 (/Sulphur .Hydrogen. 2. 51 2. 07 4.12 4. 73 3.19 3.88 4. 43 4. 06 4. 29 .98 ^ < Carbon 78.61 77.52 ^ Nitrogen 1. 17 1.18 [Oxvgen. 1.82 2. 40 Calorific value determined— Calories 8,013 7,885 14, 193 7, 781 British thermal units 14,423 14, 006 Lower Kittanning (B)— Continued. jBrook- I ville. (A). Sample as received: ( Moisture , . . . Volatile matter Fixed carbon (Ash 1 \Sulphur Hydrogen Cafbon Nitrogen Oxygen Calorific value determined— Calories British thermal units 29. 3.09 16. 66 74.79 5.46 1.18 30. 2. 31 13. 99 76. 69 7.01 1.19 31. 1.10 15. 80 75. 69 7.41 1.49 32. 0.59 16. 61 76. 76 6. 04 .91 2.20 1.60 2.30 2.00 3.60 2. 80 17. 92 71.32 7. 96 2. 29 2. 48 17. 87 70. 41 9. 24 3.03 7,679 13, 822 4.00 15.89 69. 57 10. 54 2. 85 7,415 13,347 36. 2. 35 14. 30 71.40 11.95 3. 30 4.22 75. 16 1.13 4. 24 7,382 13,288 1.80 Loss of moisture on air drying, 42 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Analyses of coal samples from Johnstown quadrangle , Pennsylvania — Continued. Lower Kittanning (B)— Continued. Brook- ville. (A). 30. 31. 32. 33. 34. 35. 36. Air-dried sample: . f Moisture 0. 91 17.03 76. 47 5. 59 1.21 0. 72 14. 22 77.94 7.12 1.21 0. 51 18. 34 73.00 8.15 2. 34 0. 49 18.23 71.85 9. 43 3. 09 0. 42 16. 48 72.17 10.93 2. 96 0. 56 14.56 72.71 12. 17 3.36 4.09 76.53 1.15 2.71 7,517 13,532 g 1 Volatile matter 1 Fixed carbon ^ (/Ash f\ Sulphur . Hvdrogen Carbon ^ Nitrogen (.Oxygen * Calorific value determined— Calories 7.836 14, 105 7,692 13,846 British thermal units 1 1. Conemaugh slope. 2. Johnstown. 3. South Fork. 4. Stony Creek, near trolley bridge between Mox- hom and Ferndale, south of Johnstown. 5. South Fork. 6. Franklin. 7. Dale. 8. Johnstown. 9. Moxhom. 19. Solomons Run, southeast of Johnstown. 11. Franklin. 12. Johnstown. 13. Near Walsall. 14. Stony Creek, Somerset County, south of quad- rangle. 15. 16. South Fork. 17, 18. Nanty Glo. 19. Vintondale. 20. Twin Rocks. 21. Near Weber Station, Blacklick Creek. 22. Twin Rocks. 23. Wehrum. 24, 25. Wehrum. Mine samples; see Bull. U. S. Geol. Survey No. 332, 1908, p. 201. 26, 27. Wehrum. Car samples; see Bull. U. S. Geol. Survey No. 332, 1908, p. 201. 28, 29. Ehrenfeld. J. S. Burrows, collector; see Bull. U. S. Geol. Survey No. 290, 1906, p. 179. 30. Scalp Level. 31, 32. Windber. Carload shipped by operators from Eureka No. 31 mine to St' Louis; see Bull. U. S. Geol. Survey No. 261, 1905, p. 51. Eureka No. 31 mine is not in the Johnstown quadrangle, and the correlation of the coal bed where the sample was procured is left open. 33, 34. Near Conemaugh Furnace. Mine samples; see Bull. U. S. Geol. Survey No. 332, 1908, p. 216. 35. Near Conemaugh Furnace. Car samples; see Bull. U. S. Geol. Survey No. 332, 1908, p. 216. 36. South Fork. DESCRIPTION BY DISTRICTS. For convenience in reference and from the commercial point of view the coal resources of the Johnstown quadrangle are described by districts, as follows: Johnstown district, South Fork-Mineral Point district, Blacklick Creek district, Windber district, and Cone- maugh Furnace district. The territory included in these different districts will be outlined in the descriptions. JOHNSTOWN DISTRICT. EXTENT. The Johnstown district includes the territory about the city of Johnstown and its suburbs; the hills along the valley of Conemaugh River, extending from East Conemaugh and Clapboard Run on the east to Laurel Run and the base of Laurel Ridge on the west; the region along Stony Creek and its tributaries, Solomons Run, Sams Run, and Bens Creek; and a few smaller areas back in the country and away from the channels of transportation. JOHNSTOWN DISTRICT. 43 CONEMAUGH COALS. CHARACTER AND DISTRIBUTION. The Conemaugh formation outcrops in all the hills in the immediate vicinity of Johnstown. In a section of 300 feet of this formation measured by John Fulton® above the Upper Freeport coal at Pros- sers Knob, near the city, but 3 inches of coal was detected about 65 feet above the Upper Freeport coal. A section was measured on the hill above the plant of the Johnstown Pressed Brick Company in which 400 feet of beds with concealed intervals were observed (see pp. 115-116), and no bed of coal was detected or reported as of workable thickness. It is probable, therefore, that in the Johnstown district the Conemaugh formation contains no bed of coal which under present conditions is of commercial importance. GALLITZIN COAL. In the vicinity of Johnstown the Gallitzin coal averages about 100 feet above the Upper Freeport coal. Some of the diamond-drill records obtained in the hills east of the city note a coal 1 foot in thickness slightly more than 100 feet above the Upper Freeport. The maxi- mum thickness of this bed appears to be less than 2 feet and it is in places less than 1 foot thick. In some of the sections a coal appears as low as 70 feet above the Upper Freeport. Where there is but a single coal in the lower 110 feet of the Conemaugh it is difficult to decide whether it is the representative of the Gallitzin or of the next lower bed, the Mahoning coal. What is believed to be the equivalent of the Gallitzin has been noted well up on South Fork of Bens Creek, also on the west side of the hill south of Kring and west of Ingleside, and there is evidence that it has been prospected in both these localities. Its position was located on the Johnstown-Geistown road, along the trolley line south of Island Park. Where measured along the roadside it is very thin. It may be said that its occurrence in the Johnstown Basin is fairly widespread but that it is too thin to be classed among the future workable beds in this part of the quadrangle. MAHONING COAL. The Mahoning coal occurs very close to and above the Johnstown ore bed and between 50 and 55 feet above the Upper Freeport coal in the region near Johnstown. It consists where seen to best advan- tage of two benches, as shown in the following section measured above the Baltimore and Ohio Railroad tunnel on Stony Creek south of Johnstown: a See pp. 17-18, this bulletin; also Second Geol. Survey Pennsylvania, vol. H2, 1877, p. 97. 44 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Section of Mahoning coal south of Johnstown. Shale roof. Ft. in. Coal 5 Shale, drab, fossiliferous 2 0 Coal 6 Fire clay, dark. It is nowhere worked, so far as known, and it can not be considered among the future workable coals of the area. ALLEGHENY COALS. GEOLOGIC POSITION. Four coals of workable thickness occur in the Allegheny formation in the Johnstown district — the Upper Freeport or Coke Yard bed, the Lower Freeport or Limestone bed, the Upper Kittanning or Cement bed, and the Lower Kittanning or Miller bed. These are also known by letters as the E, D, C', and B coals, respectively. The Middle Kittanning also occurs, but so far as known is of work- able thickness at only a few points and therefore can not be classed among the commercial coals of the district. All the coals except the Lower Kittanning lie at convenient intervals above drainage level in the hills immediately surrounding Johnstown and are exten- sively worked. The entire Allegheny formation is exposed in the Johnstown dis- trict. Several sections obtained at widely scattered points serve well to illustrate the variations in the character of its rocks as well as the intervals which separate the coals. The sections were measured by hand leveling and by rule. Some of them are as follows: (1) Section of upper part of Allegheny formation near Valley Coal and Stone Company's mine , on Stony Creek. Ft. in. Coal, Upper Freeport (E or Coke Yard coal) 3 3 Shale 14 Shales, dark, concretionary 10 Shales, blue 25 Sandstone, laminated 5 Shales and sandy shales.. Coal, 1 foot ‘ Bone, 1^ inches Coal, 1 foot 7 inches Bone, 1 inch Coal, 3^ inches Limestone Shale and sandstone Shale, blue 15 Lower Freeport (D or Limestone! coal). / 3 1 Coal, Upper Kittanning (Cement or C' coal) Shale Limestone Shale, sandy, containing limestone concretions . Sandstone, massive. 4 9 to 5 5 1 3F4 8-10 JOHNSTOWN DISTRICT. 45 The interval between the Upper Freeport and Upper Kittanning coals in the above section is about 90 feet. The section is carried still lower by one measured south of the tunnel on the Baltimore and Ohio Railroad, which shows the relative positions of two small beds occurring between the Upper Kittanning or Cement bed and the Lower Kittanning or Miller bed. This section is as follows: (2) Section of Upper Kittanning coal and underlying coals south of tunnel on Baltimore and Ohio Railroad. Ft. in. Coal, Upper Kittanning (Cement or O' bed) 5 2 Shale 8-12 Limestone 6 Shales, gray, concretionary 4-5 Shale, drab, containing abundant ferruginous limestone con- cretions 6 Shale, black 12-14 Coal 1^ Shale, blue, with ferruginous limestone concretions 6 Shale, sandy 6 10 Coal The intervals between the three main coals in the upper part of the Allegheny formation, as well as the character of the intermediate rocks, are given in the following section obtained in the ventilating shaft of the Rolling Mill mine of the Cambria Steel Company on Mill Creek: (3) Section of upper part of Allegheny formation on Mill Creek. Upper Freeport coal. Feet. Concealed 20 Concealed by mine timber 22 Shale, hard 6 Sandstone 4 Shale 3J Coal, Lower Freeport (Limestone or D coal) 1J Limestone, nodular 2 Shale, dense, drab, or clay 10 Shale, blue, irregularly bedded 4 Shale, light drab 7 Sandstone 3 Shale 3 Shale, sandy 8 Top of Cement coal. The interval between the Upper Freeport and Upper Kittanning coals here is between 90 and 95 feet. The following section was measured by F. B. Peck and W, C. Phalen on the Eighth Ward road, south of Kernville: 46 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. (4) Section of upper part of Allegheny formation on Eighth Ward road, south of Kernville. Ft. in. Coal, 3 feet 8 inchesl Main Upper Freeport ( Coke yard or El , , Clay, 4 inches coal) . f 4 d Coal, 3 inches J Clay 2 6 Coal 3 Shale 5 Shales, ferruginous 10 Sandstone, argillapeous 8 Sandstone, concretionary 3 Sandstone, massive 19 Lower Freeport (Limestone or D bed) 4 1 Shale, black Sandstone Shale, black Coal, 7-8 inches.. Bone, §-l inch Coal, 8 inches Shale, black, 2 inches Coal, 2 feet 6 inches. Shale, black Limestone 3 Shale, blue 5 Shale, massive, drab, ferruginous 7 Shale, sandy 8 Shale, blue-black 4 Coal, Upper Kittanning (Cement or O' bed) 3 Shale 1 Limestone 5 Shale 3 Shale, sandy 5 Shale, black and brown 3 Coal 1 Shales, sandy 5 Shales 20 Coal ' Shales 25 11 The interval here between the Upper Freeport and the Upper Kit- tanning coals is about 85 feet. The following section is of interest, as it shows a coal between the Lower Freeport and Upper Kittanning beds, presumably the same bed as that above the Upper Kittanning at the mouth of the Rolling Mill mine and on Dalton Run. (5) Section of upper part of Allegheny formation south of stone bridge on Stony Creek, Johnstown. Coal, 6 inches Bone, 1 inch Coal, inches Shale, 1 inch Coal, 1 foot 7 inches Fire clay Shale Lower Freeport (Limestone or D1 coal) J Ft. in. 2 9 £ 1 3 JOHNSTOWN DISTRICT. 47 Ft. in. Limestone 2 6 Shales 17-18 Coal 8 Bone 9 Shales, brown, with concretions 3 6 Shale, sandy 8 4 Top of cement coal. The following section was measured in a small gully on the main line of the Pennsylvania Railroad half a mile east of Conemaugh depot. (6) Section of upper part of Allegheny formation on Pennsylvania Railroad east of East Conemaugh. Ft. in. Coal, 3 feet 3 inches'! Bone, 2 inches >Upper Freeport (Coke Yard or E coal). 3 Coal, A.\ inches J Shales 18 Shale and sandstone beds 12 Shales 4 10 Coal 8 Fire clay 4 Limestone, green sandy 6 Sandstone, laminated 6 Sandstone, shaly 5 Sandstone, massive 40 Coal, Upper Kittanning (Cement or C' coal) 2 11J Limestone 2 Shale, gray, with limestone nodules 1 6 Limestone ’ ....^ 5 Shale, gray, with ferruginous concretions 5 Shales, blue 17 Railroad level. Shale, blue, with ferruginous limestone concretions 10 Limestone nodules, blue, to creek level. The above section was completed down to the Lower Kittanning coal by a section a short distance to the west. Part of it could not be hand leveled but had to be measured by barometer. The section is as follows: (7) Section between Upper Kittanning (C') and Lower Kittanning (B) coals. Base of Upper Kittanning (C 7 or Cement coal). Shales, bluish and gray (containing a small coal locally), with concretions; 40 feet of these shales are represented in the pre- Ft. in. ceding section 50 Coal 10i Shales, greenish blue 6 8 Sandstone, gray 1 9 Shale, black 1 5 Sandstone, blue, thick bedded 5 8 Approximate interval made up chiefly of sandstone to Lower Kittanning (Miller or B bed) 25 ± 48 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. The above sections well illustrate the character of the Allegheny rocks between the Lower Kittanning (Miller) coal and the Upper Freeport (Coke Yard) bed. The opportunities for measuring the interval from the Lower Kittanning to the top of the Pottsville are rare near Johnstown. On Clapboard Kun this interval is about 70 feet. On Stony Creek south of the area the character of the rocks making up the interval was carefully determined and the section hand leveled. This section of the lower Allegheny is as follows: (8) Section from top of Pottsville to Lower Kittanning ( Miller or B coal) on Stony CreeJc, south of Johnstown quadrangle. Coal, 3 feet inches ' Bone or black shale, inches Coal, 3§ inches Bone, 1 inch Coal, 10 inches Fire clay Sandstone, gray, laminated Sandstone, massive Shale Coal and bone Shale Sandstone, laminated Top of Pottsville. Lower Kittanning (Miller or' B coal) Ft. 5 4 9 40 2 3 10 5 8 8 7 The interval from the base of the Lower Kittanning coal to the top of the Pottsville here is about 75 feet, which is very close to the interval of 70 feet measured on Clapboard Run. In this section but one coal appears between the top of the Potts- ville and the base of the Lower Kittanning (Miller) bed, but in places two coals occur in this interval, as in the section of the lower Alle- gheny rocks obtained near the brick plant of A. J. Haws & Sons (Limited), west of Coopersdale. (See p. 24, fig. 2, section A.) Many other measurements of the intervals between the coals of the Allegheny were obtained in and near Johnstown. (See fig. 2.) These intervals and those brought out in the sections given above will be described in detail in considering the stratigraphy of the indi- vidual coal beds. UPPER FREEPORT COAL. Name and position . — In the Johnstown district the Upper Freeport or top coal of the Allegheny formation is commonly known as the Coke Yard coal, from the fact that it was coked in the early days of the iron industry at the old Cambria furnace on Laurel Run. It is also frequently referred to as the E coal. It lies at the top, indeed marks the top, of the Allegheny formation, being separated from the usually massive Mahoning sandstone member (of the Conemaugh for- mation) above by a few feet of shales, and being located between 255 and 265 feet above the top of the Pottsville formation, or 1 ‘Conglomer- U. S. GEOLOGICAL SURVEY BULLETIN 447 PLATE VII A. EXPOSURE OF UPPER KITTANNING COAL AND JOHNSTOWN LIMESTONE MEMBER ("CEMENT BED" IN THE ILLUSTRATION) ON STONY CREEK, NEAR MINE OF VALLEY COAL AND STONE COMPANY. B. UPPER FREEPORT COAL WITH OVERLYING SHALES AND BASE OF MAHONING SANDSTONE AT SOUTH PORTAL OF BALTIMORE AND OHIO RAILROAD TUNNEL, STONY CREEK. JOHNSTOWN DISTRICT. 49 ate Rock,” as it is popularly known. Its relation to the other coals in the Allegheny formation are shown in figure 2 and may be learned from most of the sections just given (pp. 44-47). Extent and development. — The Upper Freeport is present in all the hills along Conemaugh River near the city and its suburbs, extending as far to the west as the hills bordering east of Laurel Run. It is also above drainage level on Clapboard, Hinckston, and St. Clair runs and practically along the entire course of Stony Creek and its tributaries, Solomons and Sams runs. It is not above drainage level through the entire course of Bens Creek in this area, as the synclinal trough in Somerset County causes its disappearance for a short distance, but even there it is not deeply buried. Plate I gives an excellent idea of its outcrop in the vicinity of Johnstown. Wherever the coal is exposed it has been worked fairly extensively, and it is now being worked on a large scale in many mines about Johnstown. The most important workings are those of the Cambria Steel Company at the Conemaugh slope. The Ferndale Coal Com- pany also operates on an extensive scale. Many smaller mines on this coal bed are worked the year round, and many small banks, from which coal is never shipped by rail, are worked only during the winter season. The most important mines on this coal are indicated on Plate I. Chemical character. — The composition of the Upper Freeport coal in the Johnstown district is shown in analyses 1 and 2, on page 40. These analyses indicate this coal to be a high-carbon coal with com- paratively low moisture. The ash and the sulphur are high. Occurrence and physical character. — Average and typical sections of the Upper Freeport coal in the Johnstown district are shown in figure 4. The main bench averages between 3 feet and 3 feet 10 inches in thickness, more nearly the former than the latter. In places there is present a lower bench, which only exceptionally (as at the mine of Lewis Eppley, on Hinckston Run) exceeds 4 or 5 inches in thickness. This lower bench is separated from the main bench by a thin bone or shale parting rarely more than 5 or 6 inches thick. The lower part of the coal bed is in some places so intimate a mixture of coal and bone that it is difficult to differentiate the two. Such is the case in section 19, obtained at the south portal of the tunnel of the Balti- more and Ohio Railroad on Stony Creek. (See PI. VII, B.) At a bank on Bens Creek the coal shows a section (No. 21) quite different from the usual one, but this section was obtained at a point several miles away from most of the other sections, and the lack of measure- ments in the intermediate territory makes it impossible to state whether the thinning shown is local or general to the west of the Johnstown Basin. However, to the north of this point, on St. Clair 69516°— Bull. 447—11 4 50 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Run, the section seems to be as usual. Only the main bench of this coal is ever worked, and all the coal below the main bench serves as a floor, except where it is necessary to remove it for head room. As a rule no partings were noted in the main bench of this coal in the Johnstown district, a particular in which it differs markedly from the equivalent bed about South Fork and along the southeastern flank of the Wilmore Basin. Its maximum thickness nowhere exceeds 5 feet and usually ranges near 4 feet. The minimum thickness may Figure 4.— Sections of the Upper Freeport (E or Coke Yard) coal in the Johnstown district. Scale, 1 inch=5feet. 1. Lewis Eppley, Hinckston Run, above Rosedale. 2. Conemaugh slope, Cambria Steel Company, west of East Conemaugh. 3. Country bank in ravine, north of Pennsylvania Railroad, northeast of East Conemaugh. 4. L. J. Mitchell, mouth of Clapboard Run. 5. Charles Umbarger, head of Clapboard Run. 6. Johnstown Pressed Brick Company, Frankstown road. 7. William Davis, Frankstown road. 8. William Schaeffer, Shingle Run, Dale. 9, 10, 11, 12. Berkebile Coal Company, Dale, north of Moxhom. 13. Country bank, Sams Run, just above Highland Coal and Coke Company’s mine. 14. Ferndale Coal Company, Grubtown opening 15. Ferndale Coal Company. 16. Country bank, Roxbury. 17. Natural exposure along trolley line, opposite Valley Coal and Stone Company’s mine. 18. Natural exposure along trolley line, south of Island Park. 19. South portal of Baltimore and Ohio Railroad tunnel, south of Johnstown. 20. Natural exposure on Stony Creek near mine of Valley Coal and Stone Company. 21. Bens Creek, Somerset County. 22. Country bank, St. Clair Run. be regarded as 2 feet, though, as in all coal beds, local rolls pinch the coal out altogether. Such rolls, however, appear to be extremely rare in this coal bed, which is characterized by marked uniformity. There are few or no clay veins. The roof is usually shale or shaly sandstone, in places bony. It is generally firm, but draw slate is occasionally reported. In some of the mines great care is taken in propping to prevent falls. JOHNSTOWN DISTRICT. 51 LOWER FREEPORT COAL. Name and 'position . — The next lower coal of importance in the Allegheny formation in the Johnstown district is the Lower Freeport or D coal. It is popularly known as the Limestone coal, and is better known about Johnstown under this name than under either of the other two. It lies from 50 to 65 feet below the Upper Freeport (Coke Yard) coal and from 25 to 36 feet above the Upper Kittanning (Cement) coal in the valley of Stony Creek, both south and west of Johnstown. On Mill Creek it is 55 feet below the Upper Freeport coal and about 37 feet above the Upper Kittanning coal. On Peggys Run, near the Franklin mine of the Cambria Steel Company, it is 58 feet below the Upper Freeport and 45 feet above the Upper Kittanning, which is here worked. In section 6, page 47, the 8-inch coal 35 feet below the Upper Freeport coal may not be the representative of the Lower Freeport; certainly its distance below the Upper Freeport is very much less than that usual in the district as a whole. Extent and development . — The Lower Freeport coal is above drain- age level, as is the Upper Freeport bed, in all the hills near Johnstown, outcropping along Conemaugh River, Stony Creek, and their tribu- taries. Its outcrop line, if drawn on the map (PI. I), would fall between that of the Upper Freeport and Upper Kittanning coals. The coal has been prospected at many points about the city and its suburbs, but it is not mined, at least on a commercial scale, at the present time. The most promising outcrops were observed along Stony Creek from the vicinity of the mines of the Valley Coal and Stone Company northward to Roxbury. On Peggys Run, near Franklin, it was prospected and proved to be 4 feet thick but so badly broken by partings that it is not commercially valuable. It is reported 18 inches thick with a shale band in the middle in the hills north of Coopersdale. It is believed to be one of the important coals of the future in this district, especially along Stony Creek. Chemical character . — In the sample of coal collected south of Johns- town, the analysis of which is given on page 40 (No. 4), the clay part- ings were not included, as these will be discarded when the coal is worked on a commercial scale. In the analysis the percentage of carbon is high and comparable with this constituent in other coals in this district. The moisture can not be considered representative, as the sample was procured near the outcrop. The ash runs rather high but not above the average of the coals of the area. The coal from this bed is not con- sidered good in the region about Johnstown, but the analysis of the sample collected near Stony Creek (see p. 40) indicates that in this locality, where the coal is persistent and of workable thickness, it has commercial importance. 52 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Occurrence and physical character . — The Lower Freeport coal occurs as a rule in three distinct benches (see fig. 5) in the territory about Johnstown and from Ferndale southward on Stony Creek. These benches are separated by thin shale or bone partings. The top bench averages about a foot in thickness and the middle bench about 2 feet. In the commercial development of this coal bed only these two benches will be worked, the underlying coal and bone serving as a floor. It may be said, therefore, that in this locality there is present from 2J to 3 feet of coal. Southeast of Johnstown, at Dale and on Sams and Solomons runs, where this coal was meas- ured by F. B. Peck and Lawrence Martin, a thin bench, usually under 6 inches, occurs at the top of the bed, and the two main benches are below, separated by bone or shale. In this part of the district these two workable benches do not average as much coal as in the workable parts of the bed on Stony Creek. Figure 5.— Sections of the Lower Freeport (D or Limestone) coal in the Johnstown district. Scale, 1 inch=5 feet. 1. Natural exposure south of Kernville, near Qitizens Eighth Ward mine. 2. Exposure on Baltimore and Ohio Railroad, west bank of Stony Creek, opposite Lorraine Steel Com- pany’s plant. 3. Stony Creek near trolley bridge. 4. Stony Creek near Valley Coal and Stone Company’s mine. 5. West bank of Stony Creek, Johnstown. 6. Sams Run. 7. Dale. 8. 9. Head of Solomons Run. Immediately over the coal are usually a few inches of bone and black shale overlain by dense shale, sandy shale, or massive sand- stone. Plate IV, A (p. 24), gives an idea of the character of this roof. The coal is underlain by clay, below which occurs the limestone, though in places the limestone underlies the coal directly. UPPER KITTANNING COAL. Name and position . — The next lower coal of importance in this dis- trict is the Upper Kittanning coal. It is also referred to as the C' coal, but more commonly is known as the Cement seam, from the bed of cement rock which closely underlies it. In the early reports of the Second Geological Survey of Pennsylvania it was called the Lower Freeport or D coal and the coal next above it was referred to as the Middle Freeport or D' bed.® a Second Geol. Survey Pennsylvania, Rept. 112, 1877, p. xxviii. JOHNSTOWN DISTRICT. 53 The Upper Kittanning coal commonly occurs within 100 feet of the Upper Freeport (Coke Yard) bed. At Kernville the interval be- tween the two is about 90 feet; on Stony Creek near the Valley Coal and Stone Company’s mine it is 90 feet; on Mill Creek, between 90 and 95 feet; south of Kernville, on the trolley line, 84 feet. On the Frankstown road an interval of about 100 feet was measured, though it was reported that the two coals locally occur as near to each other as 80 feet. Along the main line of the Pennsylvania Railroad just east of Conemaugh depot the interval is 90 feet, and near the Franklin mines it was reported as 103 feet. It can be stated, there- fore, that about 95 feet below the Upper Freeport (Coke Yard) coal the prospector may expect to find the representative of the Upper Kittanning (Cement) coal in the Johnstown district. Sections 1, 3, 4, and 6, on pages 44 to 47, and the compiled sections obtained near Coopersdale and on Clapboard and Peggys runs (fig. 2) clearly indicate its relation to all the coals in this district. Extent and development . — The Upper Kittanning (Cement) seam outcrops at a height above drainage level that is convenient for exploitation at practically all points about Johnstown. West of the city and north of Conemaugh River the coal is worked on the estate of Lewis J. Prosser, at the north end of Ten Acre Bridge. Here the coal is just below the flood-plain level at the base of the hill and has to be reached by slopes. A short distance to the west, just back of Coopersdale, a slight rise in the beds brings this coal above the flood plain, and a few abandoned banks indicate that it was formerly worked on a small scale here. The steep rise in the formations toward the west does not allow it to appear in the hills west of Laurel Run. To the east of the synclinal axis along Hinckston Run the coal is above drainage level and was worked just above the present location of Johnstown depot. Though not now exposed at that exact point, the fairly massive sandstone which usually overlies it is well exposed near the position of the old Ray furnace. A very short distance to the east the coal appears in the cliffs bordering the railroad, and it may be traced beyond Conemaugh depot. At pres- ent there are no workings of note on it east of Johnstown depot and north of the Little Conemaugh, though, as will be seen from section 6, page 47, it is 3 feet thick and hence workable in this general locality. South of Conemaugh River, well up toward the head of Clapboard Run, the coal is worked in a small way at the present time. It is 2 feet 10 inches thick at the mine of Harry Wissinger, and this indi- cates that its thickness south of the river is much the same as that to the north, near Conemaugh depot. A few old openings on the bed were also noticed near the mouth of Clapboard Run. On Peggys Run is located Franklin No. 1 mine of the Cambria Steel Company. In the eastern part of Johnstown, on the Frankstown road, the coal 54 MINERAL RESOURCES OE JOHNSTOWN, PA., AND VICINITY. is opened at a few mines, the workings of at least one of which extend through the hill and come out on the Dale road leading to Walnut Grove. In Dale the coal has been opened by numerous private individuals and companies, and the workings extend eastward to Walnut Grove and well up to the head of Solomons Run. The more important mines and banks are shown on Plate I, and the char- acter of the coal bed will be outlined subsequently. (See pp. 54-56.) In the hill between Dale and Moxhom and on Sams Run east of Moxhom the coal is very thick (see sections 11, 12, and 13, below) and is worked by the Highland Coal and Coke Company and the Sunnyside Coal Company. Farther south, on Stony Creek, toward Kring, this coal bed thickens from 3 or 4 feet to as much as 6 feet in places, as near the mine of the Valley Coal and Stone Company, though that company mines only about 5 feet. (See PL VII, A.) In the cut on the Baltimore and Ohio Railroad north of Kring 5 feet 2 inches of coal was measured. (See section 2, p. 45.) This thick coal continues southward. The westward dips toward the Johns- town Basin carry this bed below drainage level less than a mile southeast of the Baltimore and Ohio Railroad tunnel south of Moxhom. West of Stony Creek and 2 miles southwest of Kring, on a creek unnamed on the map, the Upper Kittanning (Cement) coal has been opened by the Kelso Smokeless Coal Company. Here also more than 5 feet of coal was measured. Where observed along Bens Creek in Somerset County the bed is also of workable thickness. It has been opened near the confluence of the north and south forks of Bens Creek, on the land of Elizabeth Cable, on Dalton Run, and at the reservoir dam on Dalton Run. In this locality the small seam overlying the Upper Kittanning was observed. In the region north of Bens Creek the coal is 4 feet or more in thickness. Immediately West of Johnstown the operations of the Cambria Steel Company have been pushed westward in Upper Yoder Township beyond Mill Creek, and the coal has shown no tendency to become too thin to work. The Rolling Mill mine, in which these extensive operations are in progress., is the largest mine in the area and indeed one of the largest in the State. In the hills back of Cambria the Upper Kittanning (Cement) bed is above drainage level and has been opened in many places. At the mines of Samuel and E. W. Fuge the coal is about 3 feet in thickness. In the hills west of Morrellville the coal has been mined and may be assumed to be of workable thickness. It may be stated, therefore, that all about Johnstown the Upper Kittanning coal is workable. Chemical character. — Analyses 5 to 10, page 40, indicate the com- position of this coal. The analyses show a high-carbon coal with correspondingly low volatile matter. The moisture is low, but ash and sulphur are high. JOHNSTOWN DISTRICT. 55 23 Figure 6. — Sections of the Upper Kittanning (C' or Cement) coal in the Johnstown district. Scale, 1 inch = 5 feet. 1. Cambria Steel Company, Rolling Mill mine. 2. L. Prosser, north end Ten Acre Bridge. 3. E. W. Fuge, Cambria. 4. Samuel Fuge, Cambria. 5. 6. In cut on Baltimore and Ohio Railroad, west side of Stony Creek, opposite Moxhom. 7. In cut on Baltimore and Ohio Railroad north of Kring. 8. Natural exposure, near Valley Coal and Stone Company’s mine. 9. Valley Coal and Stone Company. 10. Kelso Smokeless Coal Company. 11. Highland Coal and Coke Company, Sams Run, east of Moxhom. 12, 13. Sunnyside Coal Company, between Dale and Moxhom. 14. George Heidingsfelder, head of Solomons Run. 15. D. D. Stoll, head of Solomons Run. 16. Jacoby mine, eastern part of Dale or Walnut Grove. 17. Wertz & Miller, Walnut Grove. 18. William Rohde, Solomons Run, east of Dale. 19. Edward Litsinger, Solomons Rim, east of Dale. 20. Suppes Coal Company, Chas. H. Suppes, jr., Dale opening. 21. 22. Citizens’ Coal Company, Dale mine. 23. Caddy mine. 24. Fyock’s mine. 25. Jacoby mine (second opening), Dale. 26. Suppes Coal Company, Chas. H. Suppes, jr., Frankstown road opening to Dale mine. (See No. 20.) 27. Natural exposure, east of Johnstown. 28. John F. Griffith, Frankstown road, Johnstown. 29. Head of Clapboard Run. 30. Cambria Steel Company, Franklin No. 1. 31. Dalton Run, at the reservoir. 32. Dalton Run, Elizabeth Cable. 33. William McAuliff, Bens Creek, near confluence of North and South forks. 56 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Occurrence and physical character . — West of Johnstown, at the Cambria openings south of Conemaugh River, and north of Cone- maugh River, the Upper Kittanning coal averages very nearly 3 feet in thickness; at one opening, however, it was only 2 feet 7 inches as measured. To the south along Stony Creek the bed gradually grows thicker, as indicated in sections 5, 6, 7, 8, 9, and 10 (fig. 6). As much as 6 feet of coal was reported in places and several measure- ments of 5 feet were made. (See fig. 6.) The bony character of the upper 8 inches is indicated in section 6, and as a rule the upper 8 to 12 inches has to be discarded. On Sams Run, east of Moxhom, and between Dale and Moxhom, according to observations made by F. B. Peck, the coal is between 3^ and 4 feet thick, generally with a few inches of bone (discarded in mining) at the top and a small bony streak about midway between the roof and floor. At Dale and on Solomons Run the bed is usually made up of good solid coal, vary- ing in thickness from nearly 3 feet to more than 4 feet, here and there with a bony streak near the middle and in many places with a few inches of bone at the top. On Peggys Run and in the exposures along the Pennsylvania Railroad the coal is not 3 feet thick and in places is less than 2\ feet thick. In Upper Yoder Township the coal ranges from 3 to 4 feet in thickness, often with one or two smaller coals above. As a rule the coal of this bed is a good clean product, generally uniform throughout. In a few of the mines the upper foot of coal is reported soft and the lower foot harder than the average. The roof of the coal is either very dense shale or else sandy shale or sand- stone and gives no trouble whatsoever. The floor is usually a few inches of firm shale or clay closely underlain by the Johnstown “cement” bed. This cement bed locally underlies the coal directly. (See PI. VII, A.) The coal bed is uniform in thickness and few rolls are reported. Clay veins are, however, numerous and in places are very annoying. Considerable trouble is often caused by gas, which necessitates the use of safety lamps. MIDDLE KITTANNING COAL. In considering the stratigraphy of the different members of the Allegheny formation the presence of two small coals between the Upper and Lower Kittanning beds was pointed out (p. 26). The lower of these coals is regarded as the equivalent of the Middle Kittanning (C) coal in the Johnstown district. South of the tunnel on the Baltimore and Ohio Railroad going to Kring the distance from the base of the Upper Kittanning (Cement) bed to this coal is 32 feet (section 2, p. 45); the coal here is only 7\ inches thick. South of Kernville, near the Eighth Ward mine of the Citizens Coal Company, this coal is 11 inches thick and is about 43 feet JOHNSTOWN DISTRICT. 57 below the base of the Upper Kittanning bed (section 4 , p. 46). Along the Pennsylvania Railroad near Conemaugh depot the inter- val between the Cement bed and the Middle Kittanning coal is about the same — namely, 45 to 50 feet — but the coal here is only 10^ inches thick (section 7, p. 47). At these different places the Middle Kit- tanning coal is not of workable thickness, and as a rule it can not be considered workable in this district. It is fairly persistent, how- ever, and hence serves as an additional check on the identity of the beds both above and below it. It has been opened at Coopersdale, at the brick plant of A. J. Haws & Sons (Limited), where it is about 25 feet above the Lower Kittanning coal and shows a thickness of 30 inches, with more concealed. It is also said to be of workable thickness at the head of Solomons Run. From what is known about it at present it can not be classed among the commercial coals of the district. LOWER KITTANNING COAL. Name and 'position . — The next lower important coal in the Alle- gheny formation is the Lower Kittanning coal. It is also known as the Miller or B bed in and near Johnstown. Its position below the Upper Kittanning (Cement) bed can be obtained by direct measure- ment at only a very few points in the Johnstown district, as most of the operations on it are conducted either by slope or incline. At the foot of the hill ascending from Kernville to Grandview Cemetery, Johnstown, the interval was reported to be 98 feet, and where hand leveled on Stony Creek south of the quadrangle it was just 100 feet. Near the Ingleside Coal Company’s mine it was reported to be 86 feet. Near the Franklin mines of the Cambria Coal Company the interval between the Upper and Lower Kittanning beds was ascer- tained by means of a bore hole to be 90 feet. It may therefore be safely assumed that the Lower Kittanning will be found 85 to 100 feet below the Upper Kittanning (Cement) bed. Extent and development . — Immediately about Johnstown the Lower Kittanning coal is near to or below drainage level and the mines work- ing the coal are either slopes or shafts. North of Conemaugh River and just at the western edge of Coopersdale the rise of the measures approaching Laurel Ridge brings the coal above drainage, and it is worked by A. J. Haws & Sons (Limited) at their brick plant. The under clay is also mined in connection with the coal. To the north on Laurel Run the coal has been opened in a small way by John Adams. East of the Haws mine the coal disappears below drainage level and does not reappear until it reaches a point just east of Conemaugh depot, where it is worked by the Keystone Coal and Coke Company. From this point as far to the east as South Fork it is above drainage level throughout nearly the entire course of 58 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Conemaugh River, varying of course in elevation above the river, owing to the Ebensburg anticline and the circuitous course of the stream. South of Conemaugh River what is possibly the Lower Kit tanning coal is worked at present by J. L. Custer well up on Clapboard Run. It has been worked near the mouth of the run by the Argyle Coal Company, but considerable difficulty was experienced owing to the irregularities in the bed, which ultimately led to the abandonment of operations. A short distance away, on Peggys Run, the Cambria Steel Company has opened its Franklin No. 2 mine. In this mine (No. 48, PI. I) much difficulty has been experienced and much ex- pensive dead work required owing to the irregularities in the coal. (See pp. 59, 60.) In the city of Johnstown the Citizens ’ Coal Com- pany has a slope to this coal bed near the Adams Street Schoolhouse, and in Kernville the coal is worked by W. J. Williams. The coal is above drainage level for a short distance on Solomons Run, coming up just at the mouth of Falls Run. To the south along Stony Creek the coal appears above drainage level near Kring, and it is worked farther south on the east side of the creek by the Ingleside Coal Company. In the suburbs west of Johnstown — that is, at Morrell- ville and on St. Clair Run — the coal is worked by W. J. Williams and by Robertson & Griffith. Thus the total number of mines on this bed in this region is about ten. Chemical character. — Analyses of this coal (Nos. ll'to 14, pp. 40-41) give an idea of its composition in the Johnstown Basin. Like the coals already considered, the Lower Kittanning (Miller) coal in the Johnstown district is a high-carbon coal low in volatile matter and moisture. The ash and sulphur show considerable varia- tion, but this may be accounted for partly by the fact that the sam- ples were collected at scattered localities. The ash and sulphur seem to be much in excess of these constituents in coals from the South Fork district. As a steam coal the Lower Kittanning ranks very high; the engines on the Pennsylvania Railroad are supplied in part with it from one of the mines along the line. The coal is also coked at Franklin by the Cambria Steel Company in by-product ovens for use in the company’s steel plant near Johnstown. It gives satis- factory results but has to be washed before coking, thereby adding to the cost of the product. Even with this additional item of cost it is found cheaper to coke this coal on the ground than to buy coke of better quality from the Connellsville region. Occurrence and physical character. — The thickness of the Lower Kittanning (Miller) coal in the Johnstown district is shown in figure 7 ; it ranges from 3^ to 4 feet, the latter figure probably being a maxi- mum for the Johnstown Basin. Except along Clapboard and Peggys JOHNSTOWN DISTRICT. 59 runs and near Franklin, the coal is on the whole regular; its floor rolls and here and there the coal is cut down to 2 feet, but rarely to less than this. Clay veins are generally absent and where present are small. In and about Johnstown, less than a foot below the base of the main bench and separated from it by shale, there is commonly a small coal, which varies from 7 to 24 inches, the latter measurement being made at the mine of the Somerset and Cambria Coal Company’s opening on Stony Creek, near Foustwell. Below the lower coal (or in its absence below the main bench) occurs a light to dark drab plastic clay, ranging from 3 to 6 feet in thickness. It was observed that where the clay was at a maximum the coal appeared in a single bench, with the lower part bony ; but it can not be stated that this condition is the usual one. The clay is of great importance near Johnstown. (See pp. 117-118.) The coal itself is in general entirely Figure 7.— Sections of the Lower Kittanning (Miller or B) coal in the Johnstown district. Scale, 1 inch=5 feet. 1. John Adams, Laurel Run. 2. A. J. Haws & Sons, Coopersdale mine. 3. A. J. Haws & Sons, shaft at brick plant. 4. W. J. Williams, Kernville. 5. Citizens’ Coal Company, Green Hill mine. 6. Cambria Steel Company, Franklin No. 2. 7. Cambria Steel Company, Franklin No. 2, outlet on Clapboard Run. 8. Keystone Coal and Coke Company, Conemaugh slope. 9. Ingleside Coal Company. 10. Robertson & Griffith, St. Clair Run. free from partings and is uniform from roof to floor. The roof is massive sandstone, tough shale, or sandy shale, requiring little or no timbering, and there is no draw slate reported. At Franklin and on Clapboard Run, on the other hand, the Lower Kittanning coal is erratic, and much difficulty has been experienced in mining on account of the irregular character of the floor. These irregularities are termed faults by the miners, but they are not faults in the geologic sense. The coal in this locality may be 6 feet thick in one place and only 15 inches thick a few feet away, and over small areas it is completely absent. It is believed that this singular 60 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINItY. occurrence is due to peculiar conditions of sedimentation during or subsequent to its original deposition in this locality, and not to subsequent movement, and that the trouble will be found to be only local and will disappear to the south. In confirmation of this belief may be cited two drill holes, one on the Frankstown road and the other near the head of Peggys Run, in which the Lower Kittan- ning coal is normally developed. So far as known, the coals above the Lower Kittanning (Miller) are normal in their occurrence; if the cause for the erratic conditions in the Lower Kittanning were regional, the Upper Kittanning (Cement) coal, which is worked at higher levels in the same hills, would probably be irregular likewise. The slight folds or rolls in the structure observed along the Penn- sylvania Railroad near East Conemaugh are considered to have had nothing to do with the peculiar conditions just described. These irregularities have led to much expensive dead work near Franklin and have caused the abandonment of large operations on Clapboard Run. LOWER ALLEGHENY COALS. Coals lower than the Lower Kittanning and yet in the Allegheny formation are exposed in this district. At Coopersdale the top of the Pottsville formation appears at road level just west of the brick plant of A. J. Haws & Sons (Limited). Just above, two small coal beds, each measuring less than 2 \ feet, are exposed, separated by about 10 feet of dark shale. The section is given on page 23. These coals probably correspond to the Brookville (A) and Clarion (A') of the Allegheny Valley. One of these, probably the lower (Brook- ville), is exposed on Clapboard Run. The Lower Kittanning seam has been opened along this run, and about 70 feet below it a coal has been worked which is considered the Brookville or a coal very close to it. Two sections of this coal are as follows: Bony coal Bone Coal Sections of Brookville coal on Clapboard Run. Ft. in. 1 8 Bone or shale 1 Coal 1 8 Bone Coal Bone or shale Coal Ft. in. 9 3 2 G 1 1 7 These sections are very similar, showing an upper bench from 18 J to 20 inches in thickness, mostly of bone and of no value, and a lower bench 19 or 20 inches thick. The coal has no value along this run. South of the quadrangle, between the mouth of Paint Creek and Foustwell, the lower part of the Allegheny, together with the whole SOUTH FORK-MINERAL POINT DISTRICT. 61 of the Pottsville and a large part of the Mauch Chunk formation, is brought above drainage level on the flanks of the Ebensburg or Via- duct anticline. The section on page 27 shows a coal 10 to 15 feet above the massive sandstone at the top of the Pottsville and separated from it by shale and sandstone. It is quite possible that this may be the Clarion coal. At least it is one of the Brookville-Clarion coal group. (See fig. 8.) POTTSVILLE COALS. The Pottsville formation lies below the Allegheny formation and, as indicated on page 28, consists of an upper and a lower sandstone member with an intervening shale member. This shale in many places carries a coal known as the Mercer. The coal appearing between the tipple of the Ingleside Coal Company and Kring, on Stony Creek south of Johnstown, is considered to belong in the Mercer coal group. The section is as follows (see also fig. 2) : Section of Mercer coal south of Kring. Ft. in. Black shale 5 6 Coal 9 Pyritiferous dark sandstone 1-2 Coal 6 Shale 2 Coal 9 Coal and bone 11 Black shale . . 3-4 Coal 4 Bone Clay 1 The coal is so badly broken that it can not be considered among the workable beds of the district. Near Sheridan the Mercer coal is about a foot thick. (See p. 119.) SOUTH FORK-MINERAL POINT DISTRICT. EXTENT. In the South Fork-Mineral Point district will be included all the coal occurrences between, in, and near the two towns named. The mining operations extend from Ehrenfeld on the east to the point where Conemaugh River makes a sharp bend to the south, about 2 miles west of Mineral Point. Operations are conducted on both sides of the river. The openings are confined to the immediate river valley, but the workings in many of the larger mines are very extensive and have been pushed back into the hills a long distance from the river. Figure 8.— Section of the Clarion (A') coal along Baltimore and Ohio Railroad near southern edge of Johnstown quadrangle. Scale, 1 inch = 5 feet. 62 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. GEOLOGIC POSITION OF COALS. The three formations which are of economic interest in the district are the Conemaugh, Allegheny, and Pottsville. The dips near South Fork are steep and the rock exposures are too imperfect to permit complete and detailed sections. North and south of Conemaugh River, however, diamond-drill holes have been put down and the rec- ords have apparently been carefully kept. Opportunity was afforded also for a measurement of the rocks in the shaft of the Pennsylvania, Beech Creek, and Eastern Coal Company near New Germany. A very clear idea, therefore, of the rocks as far down in the section as the Lower Kittanning (Miller) coal has been obtained. On South Fork of Conemaugh River, near the northernmost cottage of the group near the old dam site, the interval between the Upper Freeport and Lower Kittanning coals is 206 feet. In the shaft at New Germany the interval between the two coals is 145 feet, a decrease to the north of 61 feet. It is known that this decrease in the interval takes place within a distance of 4§ miles, and it is possible that it may occur within a shorter distance. CONEMAUGH COALS. COAL NEAR SUMMERHILL. Northwest of Summerhill, at an elevation of 1,800 feet, a coal has been opened by the side of the public road. It is reported to be exactly 300 feet above the Upper Freeport (Lemon or E) coal. The openings have entirely fallen in and no opportunity was afforded to measure the thickness or ascertain the character of the coal. The information was received that about 40 acres of territory had been worked out and that the coal was 4 feet thick. A measurement of the thickness of the part of the coal exposed along the roadside fully corroborates this information. This occurrence is probably that described by Platt under the heading “ Brown’s mine, near Summerhill.” Platt’s description is as follows : a Northeast of the outcrop [of the E coal?] the hill rises steadily for 250 feet, and near the top Mr. Brown opened up a bed of coal unlike, both in character and in position geologically, any other coal thus far known in Cambria County. It overlies the Upper Freeport bed (E) certainly by as much as 200 feet; but the intervening measures are concealed, and their character is therefore almost wholly unknown. The bed has very little cover and is irregular and uneven, both roof and floor under- going frequent changes, sometimes within a few yards. Moreover, the thickness of the bed has been very seriously affected by “horsebacks” and “clay veins,” the coal varying in width all the way from 4 feet to as many inches. Two drifts were started in on the bed at the outcrop ; one gangway is driven north- west and the other northeast. In both entries there is a sharp rise, that to the north- east being due to a local roll in the rocks of tolerably wide sweep. a Second Geol. Survey Pennsylvania, Rept. H2, 1877, pp. 38-40. SOUTH FORK-MINERAL POINT DISTRICT. 63 The following measurements of the bed, made in the northeast gangway, will serve to give a clearer expression to the actual condition of things: Section made near mouth of mine. Ft. in. Roof, ‘ 1 black slate ” 1 Coal, compact and of cuboidal structure 1 6 Coal, friable and of columnar structure 4 Coal, cuboidal structure 2 10 Floor, “slate,” alternating with sandstone. Section made 60 feet beyond last. Sandstone. Ft. in. Slate 6 Coal 2 Slate 2 Coal 1 3 Between these two measurements a “clay vein” intervenes, cutting out the coal almost entirely for a short distance. The bed then resumes its full height as given above, but diminishes steadily in going northeast, until at the end of the entry the coal is no longer of workable size, as follows: Roof, sandstone. Ft. in. Coal 1 6 Sandstone floor. At this point operations were brought to a close. In the northwest mine the coal attains its greatest thickness, but is everywhere slaty and poor; it shows, however, throughout, the same horizontal crystallization already noted in connection with the other mine. The northwest entry was driven in several hundred yards, but with practically the same results as attended the opera- tions elsewhere. These continued troubles naturally led to the abandonment of the mines. The bed is represented only in the tops of the highest hills and covers a very limited area. The rise in the rocks carries it into the air a short distance west of Brown’s openings, and east of the synclinal axis it is not known to occur. Considering the geological horizon of the bed, together with the slaty character of the coal from it, it is apparent that this is one of the seams of the Barren Measures, of which there are several, usually thin and unimportant, but here, and confined per- haps to this immediate territory, of abnormal thickness and width. The bed also undergoes such marked changes in point of character that no one specimen would fairly represent the average run of the mine. In the main, however, the coal is poor, being heavily loaded with earthy matter and other impurities. But along the center of the bed ranges not infrequently a narrow belt of soft, bright, rich clean coal, the limits of which are clearly defined both above and below by benches of smooth, tough, slaty coal. * * * Two analyses of the coal were therefore made of specimens selected and forwarded to Harrisburg by the owners of the property, the Messrs. Brown, of Summerhill. The first analysis represents the small bench of soft friable coal, and reads as follows (D. McCreath): Water at 225° 0. 820 Volatile matter 19. 155 Fixed carbon 70.175 Sulphur 445 Ash.,, 9.405 100. 000 64 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Coke, per cent, 80.025; color of ash, gray. The coal is bright, tender, and seamed with charcoal and pyrites. The other analysis may be said to represent the condition of the greater portion of the bed. The large percentage of ash, nearly one-fifth of the whole, gives to this coal its firmness and compactness and also its slightly conchoidal fracture and dull luster, but at the same time it ruins the bed totally for all practical purposes. The analysis also shows that this cannel slate is more sulphurous than the bench of soft coal in the center of the bed. The analysis is as follows (D. McCreath): Water at 225° 0. 550 Volatile matter 17. 325 Fixed carbon 61. 632 Sulphur 1. 033 Ash 19. 460 100. 000 Coke, per cent, 82.125; color of ash, gray. The coal is exceedingly compact, has a dull, resinous luster generally, but carries seams of bright crystalline coal. GALLITZIN COAL. South of South Fork a coal appears in the sections about 115 feet above the Upper Freeport (Lemon or E) bed. From its interval this is probably the representative of the Gallitzin bed. It is not work- able, as it is rarely more than a foot thick. North of South Fork this coal is about 65 feet above the Upper Freeport coal. Another coal, possibly the Mahoning, appears below it in the section; this likewise is not workable near South Fork. ALLEGHENY COALS. Four coals have been worked in the Allegheny formation in the South Fork-Mineral Point district. They are (1) the Upper Free- port or E coal, which is known near South Fork and also along the eastern margin of the Wilmore Basin as the Lemon coal; (2) the Upper Kittanning or Cement coal; (3) the Lower Kittanning, Miller, or White Ash coal; and (4) the Brookville, usually referred to as the Dirty A coal. The first three are of greatest importance in this district. UPPER FREEPORT COAL. Name and 'position . — As stated above, the Upper Freeport coal is known at South Fork as the Lemon coal. It is also sometimes called the E bed, having been so termed by the geologists of the Second Geological Survey of Pennsylvania. It is also often referred to as the Four-foot coal. The position of this coal at the top of the Allegheny and its relations to the lower Allegheny coals are shown in figure 2. Its position with reference to the Mahoning sandstone in the South Fork district is indicated in the following section measured at Ehrenfeld : SOUTH FORK-MINERAL POINT DISTRICT. 65 Section of Upper Freeport {Lemon) coal and associated beds at Ehrenfeld , Pa. Ft. in. Shale 15 Shale, olive and drab, locally sandy (Upper Mahoning?) 30 Coal (Mahoning, upper bench) 4-5 Shale 8 Shale, black 2 Shale, blue and black 1 Coal (Mahoning, lower bench) 2 Shale 15 Shale, blue, with alternating layers of fine-grained sandstone.. 20 Sandstone, massive (Mahoning) 20 Coal, 1 foot Ilf inches] Bone, 2 inches lUpper Freeport coal 3 9f Coal, 1 foot 8 inches. . J Clay, with limestone nodules in lower foot 2 Limestone, irregularly bedded (Upper Freeport) lf-3 Fire clay in places 1± Shale 15+ Extent and development . — The Upper Freeport coal appears above drainage level just east of Ehrenfeld, and has been opened at rail- road level by the Pennsylvania, Beech Creek, and Eastern Coal Com- pany at its No. 8 opening. Not far to the west, but higher in the hill owing to the rapid rise of the beds westward, is located mine No. 6 of the same company. This mine was not being worked in the summer of 1906, at the time of visit. West of Mineral Point this coal is present in the hills bordering Conemaugh River, but at varying distances from it. (See PL I.) It has been opened in a small way in one or two places, but where seen the openings had fallen in. South of Conemaugh River it has been worked in and near South Fork by the South Fork Mining Company, and on the west side of South Fork of the Conemaugh by O. M. and H. C. Stineman. It is also present in the hills along the south side of the river, but it has been hardly touched there up to the present time. Chemical character . — Analysis No. 3, page 40, shows the character of this coal near South Fork. It compares favorably with the other coals in the Johnstown quadrangle, and the analysis shows the normal high carbon content, with low volatile combustible matter. Moisture and ash are also low, but sulphur is high. The product from this coal bed is used chiefly for steaming purposes. It is also coked in beehive ovens at Cresson, Gallitzin, and Bennington with satisfactory results. Its composition along certain parts of the Allegheny Front — at Gal- litzin, for instance — is different from that of the coal near South Fork, as the following analyses will show. The percentage of fixed carbon is lower and that of volatile matter higher in the Ebensburg region 69516°— Bull. 447—11 5 66 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. than on the west side of the basin at South Fork. The coal collected at Sonman, Puritan, and Dunlo, however, is very much the same in composition as that near South Fork and Johnstown. Analyses of Upper Freeport coal in Ebensburg quadrangle. a 1 . 2. 3. 4. 5. 6. 7. Moisture 0.52 0.63 0. 41 1.41 0. 43 0. 47 0. .41 Fixed carbon 66. 00 64. 43 74.71 71.26 72.89 74. 17 73. 17 Volatile matter 26. 59 27.92 19. 41 20.05 17.77 18. 44 17.83 Ash 6. 89 7.02 5.47 7.28 8.91 6. 92 8. 59 Sulphur 1.21 .94 1.38 3. 34 1.83 1.71 1.53 a Ebensburg folio (No. 133), Geol. Atlas U. S., U. S. Geol. Survey, 1905, p. 9. The samples whose analy- ses are given above were collected by Charles Butts. 1, 2. Pennsylvania, Beech Creek, and Eastern Coal Company, Gallitzin. W. T. Schaller, analyst. 3. Shoemaker Coal Company, Sonman. W. T. Schaller, analyst. 4. G. Pearse & Sons, Puritan. W. T. Schaller, analyst. 5. 6, 7. Mountain Coal Company, Dunlo. Analysis made at Metallurgical Laboratory, Pittsburg, Pa. Occurrence and physical character .-*- The Upper Freeport coal about South Fork may occur in either two or three benches, of which only Figure 9. — Sections of the Upper Freeport (E or Lemon) coal near South Fork. Scale, 1 inch=5feet. 1, O. M. Stineman No. 3; 2, H. C. Stineman No. 5; 3, Pennsylvania, Beech Creek and Eastern Coal Com- pany No. 8; 4, natural exposure in railroad cut at Ehrenfeld; 5, South Fork Coal Mining Company No. 2 Figure 10. — Sections of the Upper Freeport coal along the southeastern margin of the Wilmore Basin (after Butts). Scale, 1 inch=5 feet. 1, Webster No. 11 mine, southeast of Gallitzin, Pa.; 2, Shoemaker mine, Sonman; 3, Hopfer’s mine, Trout Run; 4, George Pearse & Sons, Puritan; 5, Beaverdam Run, near Pavia road; 6, Logan Coal Com- pany, Beaverdale; 7, Dunlo. the two lower are workable, and in this respect it differs essentially from the same coal about Johnstown. At Ehrenfeld and at opening No. 8 of the Pennsylvania, Beech Creek, and Eastern Coal Company, on the opposite side of Conemaugh River, only two benches were observed, and the upper bench is for the most part very much thicker than the corresponding middle bench at places where three are SOUTH FORK-MINERAL POINT DISTRICT. 67 present. The upper of the workable benches ranges in thickness from 1 foot to 2 feet and the lower bench from 1J to 2 feet. The bone or shale between the two main benches ranges from half an inch to 2 inches. It is very persistent in this district and is usually pres- ent also in this bed along the southeast margin of the Wilmore Basin. Figures 9 and 10 show the general similarity of this coal bed on both sides of the Wilmore Basin. LOWER FREEPORT COAL. The next lower coal in the South Fork district is the Lower Free- port coal, which lies from 40 to 50 feet below the Upper Freeport coal. It is persistent and is shown in most of the diamond-drill records, but it has not been developed in this district. Locally it is of workable thickness; in some of the well records it measures as much as 2\ feet solid coal with no partings; in others it consists of two benches separated by a thin binder. The two benches taken together would constitute a workable bed. In most of the sections studied it is so badly broken up or so thin as to be of no value; and it therefore can not be classed among the commercial coals in this district at present. UPPER KITTANNING (CEMENT) COAL. Name and 'position . — The next lower coal — the Upper Kittanning (Cement) bed — is an important coal near South Fork. It corresponds to the same bed about Johnstown, though it is not at this time so im- portant as the coal in that district. It occurs nearly midway between the Upper Freeport (Lemon or E) coal and the Lower Kittanning (Miller) bed. North of Conemaugli River, therefore, where the inter- val between these two coals is only 145 feet (as near New Germany), it occurs about 67 feet below the Upper Freeport coal and about 75 feet above the Lower Kittanning. South of the river, where the interval between the Upper Freeport and Lower Kittanning is approximately 200 feet, it is again about midway between the two, its distance below the former and above the latter ranging from 92 to 105 feet. Extent and development . — The Upper Kittanning is worked for local supply in the town of South Fork by Robert A. Giles and Charles Hutzel. Other (abandoned) banks in the town were observed. West of the town and on the west side of South Fork it is worked on a considerable scale by H. C. and O. M. Stineman. The coal is present in the hills westward to Mineral Point and beyond. Near Mineral Point two small mines on this coal bed belong to H. W. Gillan. (See PI. IV, B.) Chemical character . — Analysis No. 5, page 40, indicates the com- position of this coal in South Fork. The coal is bright and lustrous 68 MINERAL RESOURCES OP JOHNSTOWN, PA., AND VICINITY. and the analysis shows it to be on a par with the corresponding coal in the Johnstown district. Both its ash and sulphur average below those of the coal in that district, but in other respects the analyses are very similar. To the east, in the Ebensburg quadrangle, this coal is locally workable and has been opened and worked by G. Pearse & Sons at Puritan, on Trout Run. The composition of the coal here, as shown in the table below, is about the same as it is farther west, about South Fork; but analyses of the two samples collected in the same mine show considerable divergence. Analyses of Upper Kittanning coal at Puritan. [W. T. Schaller, analyst.] 1 . 2. Moisture 1.70 0.52 Volatile matter 19. 28 22.00 Fixed carbon 71.19 67.49 Ash 7.83 9. 99 Sulphur 1.60 3. 47 Occurrence and 'physical character. — In thickness the coal ranges from 3 to 3J feet, usually without any partings, and has a hard shale roof which gives no trouble. There is in places a few inches of bone 2 3 5 e 8 Figure 11.— Sections of the Upper Kittanning (Cement or C') coal in the South Fork-Mineral Point district. Scale, 1 inch= 5 feet. 1, H. C. Stineman No. 6, South Fork; 2, O. M. Stineman, No. 3J, South Fork; 3, Robert A. Giles, South Fork; 4, Charles Hutzel, South Fork; 5, Old opening, southern partof South Fork; 6, 7, H. W. Gillan,near Mineral Point; 8, Salt Lick Run. at the top, which is discarded in mining. The lower part of the coal is locally bony. Below this, and in its absence directly below the coal, there is a band of clay, ranging from a few inches to more than 2 feet. Below the clay, or just below the coal itself, is found a bed of limestone or cement rock — the Johnstown limestone member — measuring in places as much as 4 feet. Figure 11 indicates graphically what has been outlined above. In the area to the east the coal is locally workable, and where exploited by G. Pearse & Sons, on Trout Run, on the east side of the basin, SOUTH FORK-MINERAL POINT DISTRICT. 69 in the Ebensburg quadrangle, its thickness is very much the same as near South Fork. At Bennington it is 2 feet 10 inches thick; in the Sonman shaft it is 2 feet; in the Yellow Run shaft 2 feet 6 inches; and in a diamond-drill hole of the Henriette Mining Company, south of Llanfair, it is 1 foot thick. On the east side of the basin, therefore, it can not be considered more than locally workable. On the west side of the basin it may be regarded as among the future important coals, both near South Fork and in the region to the south, where considerable exploratory work with the diamond drill has showed this coal to be 3 feet or more in thickness. LOWER KITTANNING (MILLER) COAL. Name and 'position . — The Lower Kittanning, Miller, B, or White Ash bed is the most important coal in the South Fork-Mineral Point district. Immediately about South Fork it lies 160 feet below the Upper Freeport bed; elsewhere it ranges from 145 to 200 feet below the Upper Freeport coal (see p. 24) and about half as much below the Upper Kittanning (Cement) bed. Its position, approximately 55 to 65 feet above the top of the Pottsville (or “conglomerate rock/’ as the Pottsville is popularly called), should serve to locate and identify it with little trouble in the South Fork-Mineral Point district. Extent and development . — North of Conemaugh River the coal has been opened by the Pennsylvania, Beech Creek, and Eastern Coal Company and worked at its No. 3 and No. 5 mines, the workings in the latter being on the dip of the bed. Farther west the Priscilla Coal Company is working the same bed, and still beyond, near the Ebensburg (Viaduct) anticlinal axis, are the openings of the Keystone Coal and Coke Company, called Argyle Nos. 1 and 2 mines. There are also a few abandoned mines on the Lower Kittanning bed north of Conemaugh River, and to judge from the culm heaps at their tipples large bodies of coal have been removed from them. South of the river and west of South Fork the workings on the Lower Kittanning coal are extensive. The mines here include collieries Nos. 2 and 4 of the Stineman Coal and Coke Company and colliery No. 1 of the Stineman Coal Mining Company. To the east and in the town itself are the workings of the South Fork Coal Mining Company. The magnitude of the coal industry at South Fork may be judged from the fact that in 1905 there were produced in these mines 1,400,000 tons of coal, valued at $1,500,000. Chemical character . — Analyses Nos. 15, 16, 28, an d29 (pp. 40-42) give an excellent idea of the high grade of this coal as mined near South Fork. The analyses below give an idea of its composition in the Ebensburg quadrangle, on the southeast flank of the Wilmore Basin. 70 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Analyses of Lower Kittanning ( Miller ) coal in the Ebenshurg quadrangle . a [Air-dried samples; W. T. Schaller, analyst.] 1 . 2. 3. 4. 5. 6. 7. Moisture 0.53 0.32 0. 57 0. 38 0.36 0.35 0. 43 Volatile matter 26.90 21.97 23.52 19. 44 20.46 17.81 19. 41 Fixed carbon 63.52 71.38 69.64 74. 28 72. 76 74. 28 75. 78 Ash 9. 05 6. 33 6. 27 5. 90 6.42 7. 56 4. 38 Sulphur 1.21 .68 .99 .72 1.74 3. 14 .76 a Ebensburg folio (No. 133), Geol. Atlas U. S., U. S. Geol. Survey, 1905, p. 9. 1. Reed & Bradley mine, Bennington. 2, 3. Lilly Mining Company, Bear Rock Rim. 4. A. C. Blowers, Bens Creek. 5, 6. Alton Coal Company, Lloydell. 7. Henriette Coal Company, near Llanfair. 1 to 6 collected by Charles Butts; 7 by W. C. Phalen. From the analyses (pp. 40-42) it appears that the fixed carbon in the samples collected in the Johnstown quadrangle, near South Fork, ranges from 74 to more than 78 per cent, with volatile matter ranging from 14 to more than 16 per cent. The moisture of the samples as received at the laboratory is low, not exceeding 3.5 per cent. The samples from South Fork are notably low in sulphur and ash and show the excellent character of the Lower Kittanning (Miller) coal in this part of the Wilmore Basin. The samples collected from the Ebensburg quadrangle by Charles Butts and W. C. Phalen during the summer of 1903 were analyzed in the chemical laboratory of the Survey at Washington and not in the laboratory of the technologic branch of the Survey at St. Louis. The results of analyses are there- fore not strictly comparable with the results of analyses from South Fork (pp. 40-42). The former show more diversity in composition-, as would naturally be expected when the scattered places from which the samples were collected are considered. The general similarity of the results, however, is noteworthy, as is also the low content in sulphur and ash. The second sample collected from the Alton Coal Company’s mine at Lloydell (No. 6, above) seems to be entirely exceptional regarding its sulphur content, and it is probable that a “sulphur ball” found its way into the sample without being suspected. Steaming tests . — As a steam coal the Lower Kittanning (Miller) coal from the South Fork district ranks among the very best of western Pennsylvania and probably equals in steaming value any other steam coal in this part of the State. (See comparative tables, p. 37.) In the following tables are given the results of tests on run-of- mine coal loaded under the supervision of J. S. Burrows, formerly of the Survey, collected from No. 3 mine of the Pennsylvania, Beech Creek, and Eastern Coal Company, at Ehrenfeld. One coking test, five steaming tests, and one producer-gas test were made on the car- SOUTH FORK-MINERAL POINT DISTRICT, 71 load sample collected.® A steaming test was also made on this sample mixed with eoal from the Darby mine of the Darby Coal and Coke Company, at Darby, Lee County, Va., but the results of this test are not given in the bulletin cited. The analysis of the carload sample tested is as follows (for mine samples see analyses 28 and 29, pp. 41-42): Analysis of carload sample of Lower Kittanning coal from South Fork -Mineral Point district. Laboratory No 2152 Air-drying loss 2. 90 Moisture 3. 51 Volatile matter 16. 82 Fixed carbon 73. 04 {Ash 6. 63 '{Sulphur 94 Hydrogen 4. 56 Carbon 80. 70 Nitrogen 1. 26 Oxygen 5.91 Calorific value determined : Calories 7, 933 British thermal units 14, 279 The results of the steaming tests on this coal are as follows : Steaming tests on Lower Kittanning coal from South Fork- Mineral Point district. Test 236. Test 237. Test 238. Test 239. Test 242. Heating value of coal. .B. t. u. per pound of dry coal. . 14,886 14,868 14,828 14,690 14,659 Force of draft: Under stack damper inch water. . 0.43 0.45 0.50 0.63 0. 47 Above fire do .15 .16 .17 .19 .16 Furnace temnerature °F._ 2,317 2,266 2,212 2,059 Dry coal used per square foot of grate surface per hour pounds. . 15.74 16.23 15.69 17.64 14.33 Equivalent water evaporated per square foot of 2.93 water-heating surface per hour. . . pounds.. 2.96 2.93 3.08 2.92 Percentage of rated horsepower of boiler developed. . . Water apparently evaporated per pound of coal as 82.0 83.0 82.1 86.5 81.9 fired pounds.. 8.51 8.27 8.44 7.98 8.52 Water evaporated from and at 212° F.: Per pound of coal as fired do 10.12 9.85 10.05 9.52 10. 17 Per pound of dry coal do 10.37 10. 17 10. 42 9.75 10.22 Per pound of combustible do 11.20 11.02 11.29 10. 71 11.15 Efficiency of boiler, including grate. Coal as fired: percent.. 67.27 66.06 67.86 64. 10 67. 19 Per indicated horsepower hour. pounds.. 2.79 2.87 2.81 2.97 2.78 Per electrical horsepower hour. Dry coal: do 3.45 3.54 3.47 3.67 3. 43 Per indicated horsepower hour. do 2.73 2.78 2. 71 2.90 2.77 Per electrical horsepower hour. , do 3. 37 3. 43 3.35 3.58 3.41 Proximate analysis: Moisture 2. 37 3.11 3.56 2.44 0.42 Volatile matter 16. 74 15.68 16.09 16. 64 17.51 Fixed carbon 74.66 74. 93 73.85 73.69 75.20 Ash 6.23 6.28 6. 50 7.23 6.87 100.00 100.00 100.00 100.00 100.00 SulDhur .88 .89 .87 1.12 1.01 Bull. U. S. Geol. Survey No. 290, 1906, pp. 178-181. 72 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Steaming tests on Lower Kittanning coal from South Fork- Mineral Point district — Continued. Test 236. Test 237. Test 238. Test 239. Test 242. Ultimate analysis: Carbon a 84. 14 84.03 83. 81 82. 98 83.35 Hydrogen a 4. 34 4.35 4. 33 4. 28 4. 15 Oxygen o 2. 93 2.91 2.91 2. 89 3. 27 Nitrogen o 1.31 1.31 1.31 1.29 1.32 Sulphur .90 .92 .90 1. 15 1.01 Ash 6. 38 6.48 6. 74 7.41 6. 90 100.00 100. 00 100.00 100.00 100. 00 a Figured from car sample. Test 236: Size as shipped, run of mine. Size as used, over 1 inch, 6.5 per cent; \ inch to 1 inch, 13.6 per cent; J inch to J inch, 22.4 per cent; under -J- inch, 57.5 per cent. Duration of test, 9.88 hours. Kind of grate, rocking. Test 237: Size as shipped, run of mine. Size as used, over 1 inch, 5.8 per cent; £ inch to 1 inch, 12.3 per cent; \ inch to ^ inch, 19.5 per cent; under £ inch, 62.4 per cent. Duration of test, 10 hours. Kind of grate, rocking. Test 238: Size as shipped, run of mine. Size as used, over 1 inch, 5.4 per cent; § inch to 1 inch, 9.1 per cent; J inch to £ inch, 14.9 per cent; under \ inch, 70.6 per cent. Duration of test, 10.02 hours. Kind of grate, rocking., Test 239: Size as shipped, run of mine. Size as used, over 1 inch, 4.4 per cent; \ inch to 1 inch, 8.8 per cent; J inch to i inch, 16.2 per cent; under £ inch, 70.6 per cent. Duration of test, 9.92 hours. Kind of grate, rocking. Test 242: Size as shipped, run of mine. Size as used, over 1 inch, 2.0 per cent; \ inch to 1 inch, 7.0 per cent; £ inch to \ inch, 14.5 per cent; under £ inch, 76.5 per cent. Dried coal. Duration of test, 7.88 hours. Kind of grate, plain. » The figure giving the number of pounds of water evaporated by 1 pound of dry coal from and at a temperature of 212° F. gives the results of the coal tested so far as these relate to its commercial value, and the reader is referred to the table on page 37 for the standing of the Ehrenfeld coal among other standard steaming coals. The results of the tests, on the Ehrenfeld samples though showing a range of 9.75 to 10.42 pounds of water evaporated per pound of dry coal used, are yet, when averaged, among the very best made at the testing plant. Coking tests . — The coal from the lower Kittanning bed near South Fork has been coked, and the results of the test on the sample from Ehrenfeld are given below : Coking test on Lower Kittanning coal from Ehrenfeld. [Run of mine; finely crushed; raw; duration of test, 51 hours.] Coal charged pounds. . 10, 000 Coke produced do 5, 223 Breeze produced do „ 1, 600 Coke produced percent.. 52.23 Breeze produced do 16. 00 Total percentage yield 68.23 The product was a soft, dense coke of a dull-gray color, in large and small chunks. There was a heavy black butt on the coke, and it was hard to burn. The cell structure was small. SOUTH FORK-MINERAL POINT DISTRICT. 73 Analyses of coal and coke. Coal. Coke. Moisture 3.32 0. 91 Volatile matter 15.56 2. 16 Fixed carbon 74. 29 88.99 Ash 6. 83 7.94 Sulphur 1. 12 .91 The yield of coke from this test is comparatively high, but the poor quality of the coke shows that the coal does not belong among the best coking coals of western Pennsylvania and West Virginia. Coke made by the Cambria Steel Company with coal mined from this bed about Ehrenfeld proved well adapted to metallurgical purposes. The yield also was satisfactory. Cupola tests . a — In connection with the tests of coals made at the plant of the United States Geological Survey at St. Louis in 1904 practical melting tests were made of coke that showed any likelihood to be of value to the foundry industry. Among those tested was one made from coal collected at colliery No. 3 of the Pennsylvania, Beech Creek, and Eastern Coal Company at Ehrenfeld. The test was con- ducted in a 36-inch foundry cupola lent by the Whiting Foundry Equipment Company, of Chicago. The 36-inch shell of the cupola was relined to 26 inches internal diameter. There were four horizontal tuyeres measuring 4 by 6 inches on the outside and 3 by 13 inches on the inside of the cupola, which were situated 1 1 inches above the sand bottom. The total tuyere area was 96 square inches, giving a ratio of 1 to 5.96 with the cupola area. A No. 6 Sturtevant fan run at 2,514 revolutions a minute furnished the blast, which was kept at about 7 ounces. The cupola test was conducted by W. G. Ireland, and the details of the method employed are outlined in the references cited above and will not be given here. The results of the test are shown in the fol- lowing table: a Prof. Paper U. S. Geol. Survey No. 48, pt. 3, 1906, pp. 1367-1370; Bull. U. S. Geol. Survey No. 336, 1908, pp. 48, 49, 50, 54, 57, 60, 63. Cupola tests on Lower Kittanning ( Miller ) coal from Ehrenfeld. 74 MINERAL RESOURCES OE JOHNSTOWN, PA., AND VICINITY. •3 © tea S 2 bfi c £ 2 Scrap. coo> f co Pig iron. 00 CO - S 2 -*33 O © (M O iO 00 IO IO a^ o o c- 5 i a ps © cl v oqO iQ 00 t5 © '•(soqoni) sajo^ni jo doj 0 a o q b jqSi0H 16. 33 || © O o •(spnnod) ( — ) 0SB0JD0P JO (+) 9SB9J0UJ *o + 6 % to •0SB9J0 -ap JO 9SB9J9UJ Decrease . *© '93109 OJ UOJJ 7.20 6.50 •(juao jad) ssoj SurjpK 9.07 9.60 *© a o T3 • 2$ 0) 33 > fl '93[O0 81 49 o £ « | O 3 O o 0) Q, 'UOJJ 00 05 Cd 05 Middle Kittanning (C) coal 2 Coal, 6J inches J Shales 7 Chiefly clay 5 Sandstone 3 Shale, black 2 Sandstone with black shale partings 5 Shale, sandy, becoming concretionary and ferruginous at base. 20 Interval 4 Shale, variegated black and drab 6 Coal, 3 feet 8 inches. Shale, 2 inches Coal, 4 inches Clay, 2 inches Coal, 9 inches Shales, sandy Fire clay, dark gray 3 Sandstone, drab, resembling ganister Clay, light drab 3 Lower Kittanning (B or Miller) coal 5 in. io§ 8 2 1 4 2 8 1 6 5 2-3 The Middle Kittanning (C) coal, the first above the Lower Kittan- ning (Miller or B) bed, which is the coal worked along Blacklick Creek, occurs at an interval above it of about 50 feet. This coal is nearer the Lower Kittanning at Nanty Glo, having been reported only 34 feet above it near the opening of the Ivory Hill Mining Company at that place. At Big Bend its interval above the Lower Kittanning is about 45 feet. 80 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. There is still another coal at the top of the section deserving attention. At Yintondale a gully was dug up the hill from railroad level where the Lower Kittanning coal outcrops. The section given above, except the part between the Lower and Middle Kittanning coals, was measured in this gully. The top coal was observed by hand level to be 108 feet above the intermediate (Middle Kittanning or C) coal, and the interval between the Lower and Middle Kittan- ning beds was found to be 46J feet. Thus from the top coal to the Lower Kittanning (B) bed the distance is about 164 feet. At Nanty Glo a workable coal (probably the Lower Freeport or D coal) was observed by hand-level measurement to occur 150 feet above the Lower Kittanning coal, and at Twin Rocks a coal was reported at almost exactly the same interval by the engineer of the Big Bend collieries. At Welirum certain of the diamond-drill records show a coal about the same interval above the Lower Kittanning coal. So far as the writers are aware, this is the highest coal of any impor- tance in the Blacklick Creek district. About 50 feet above it occurs an unworkable small coal, which is regarded as the equivalent of the Upper Freeport or E bed. The highest workable coal along Blacklick Creek will therefore be regarded tentatively as the Lov^er Freeport (D) coal. The nomenclature of the coals discovered in the Blacklick Creek district and the intervals between them have been graphically given by DTnvilliers.® Fie places the first coal above the Lower Kittanning (B) at 60 feet above it, but the hand-leveled sections at Vintondale, as well as measurements made at Twin Rocks and reports from authorities at Nanty Glo, make this coal at least 15 feet lower, and instead of lettering it C', as DTnvilliers has done, the writers prefer to regard it as the C coal and the representative of the Middle and not the Upper Kittanning bed. Further, DTnvilliers places the next higher coal at 1 20 feet above the Lower Kittanning (B) and the next at approximately 60 feet higher. This bed, which he denotes as the E with a question, he describes as a “good bed, thinning westward to about 3 feet.” It is believed that this is the coal measured at Nanty Glo, at Twin Rocks, near Rexis, and on Mardis Run, though the interval obtained (150 to 160 feet above the Lower Kittanning bed) falls short by at least 20 feet of the interval platted by DTnvilliers. ALLEGHENY COALS. LOWER FREEPORT (d) COAL. Name and 'position . — Some question arises as to whether the highest workable coal in the Allegheny formation is the Upper or Lower Freeport. It is quite certain that the full complement of coals in the formation is not developed along Blacklick Creek, at a Summary Final Rept. Geol. Survey Pennsylvania, 1895, pi. 415, p. 2222. BLACKLICK CREEK DISTRICT. 81 least not as clearly as in the Johnstown Basin. Only three workable coals in the Allegheny (above and including the B bed) were deter- mined with any certainty, and, though more may be present, they must be small and hence of no value except for stratigraphic purposes. The position of the highest workable coal is very definitely fixed. At Nanty Glo it is just 150 feet by hand level above the Lower Kittan- ning (B) bed. On the Selderville road, between Nanty Glo and Twin Rocks, the interval, measured by barometer, is 1 58 feet ; at Yintondale, by hand level, it was made 164 feet; and, as stated by the engineer gf the Big Bend collieries, the interval at Big Bend is about 150 feet. There is a question as to whether this coal is the Upper Freeport or the Lower Freeport, and this question the writers are unable to settle definitely. Objection should not be made to its being considered as the Upper Freeport on the basis of its small interval above the Lower Kittanning coal, as this interval is even less than 150 feet at New Germany. In this report, however, it will be regarded as the Lower Freeport coal. Extent and development . — The Lower Freeport (D) coal has been opened by the Ivory Hill Coal Mining Company east of Nanty Glo and on the side of the hill just west of the No. 14 colliery of the Pennsylvania, Beech Creek, and Eastern Coal Company. It has been prospected and its position and character are well known at Twin Rocks and to the northeast, opposite No. 2 colliery of the Big Bend Coal Mining Company. About Yintondale it has been pros- pected and its character is known, as a section of the coal near Rexis was measured by Mr. Martin. On Mardis Run, just off the northwest corner of the Johnstown quadrangle, the coal is opened and a section was measured. At present it is not a commercial factor in the Blacklick Creek district, but it can be classed among the future commercial coals of this district. Occurrence and physical character . — Figure 14 shows the mode of occurrence of the Lower Freeport coal. It generally consists of two 1 2 3 4. 1 Figure 14.— Sections of the Lower Freeport (D) coal along Blacklick Creek. Scale, 1 inch = 5 feet. 1, Mardis Run near northwest edge of Johnstown quadrangle; 2, Blacklick Creek near Rexis; 3, road south of Twin Rocks; 4, Twin Rocks; 5, Ivory Hill Coal Mining Company, Nanty Glo. or three benches separated by thin bone partings, the coal aggre- gating from 3 to 3J feet in thickness. At Yintondale, Twin Rocks, 69516°— Bull. 447—11 6 82 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. and Nanty Glo the upper bench varies from 1J to nearly 2 feet in thickness, and the lower bench averages about 15 inches, with some few inches of bone beneath. At Twin Rocks this is underlain by a few inches of coal. On Mardis Run the coal is more broken, consisting of three benches, each about a foot thick. The roof is usually shale and the coal is underlain by clay. The presence of the parting in this coal has been a drawback to operations on it, but it is quite prob- able that it will yet be worked; in fact, it was worked during the hard- coal famine of 1902-3 and gave satisfaction. If proper care is exer- cised in separating the bony parting, it should be readily marketed. The resemblance of the sections to those of the Upper Freeport coal near South Fork is marked. MIDDLE KITTANNING COAL. A little more than 100 feet below the Upper Freeport coal and from 35 to 45 feet above the main coal of the Blacklick district (Lower Kittanning or Miller bed) occurs a coal which is persistent along South Branch of Blacklick Creek. It has been observed at Twin Rocks, Nanty Glo, and Vintondale, and its interval with respect to the main Blacklick coal has been measured at the two last-named places. It has been called the Middle Kittanning coal because it is the first coal above the Lower Kittanning bed. At Vintondale the following sec- tion was measured : Section of Middle Kittanning coal at Vintondale. Shale roof. Ft. in. Coal 2 3 Clay 1 Coal 6| Clay. The coal here has a thickness of 33 \ inches and is therefore workable. Owing to its persistence, it may be regarded as among the coals that will in the future be worked in this region, though it may be some time before it will be necessary to draw on this coal as a source of supply. LOWER KITTANNING (b) COAL. N ante and 'position . — The main coal of the Blacklick district is con- sidered the Lower Kittanning (Miller or B) coal and corresponds to this coal about South Fork. Some question has been raised as to this correlation and the coal has been regarded as the equivalent of the Upper Kittanning or C' coal. The objections to the latter view have been summed up by DTnvilliers® in the following words, with which the writers are in full agreement. The whole character of the “Blacklick seam” is totally unlike the appearance of the Kittanning upper bed(C / ) as exposed anywhere in Clearfield, Cambria, or Somerset counties. On the other hand, its double structure, columnar cleavage, partings, roof a Summary Final Rept. Geol. Survey Pennsylvania, 1895, p. 2222. BLACKLICK CREEK DISTRICT. 83 and floor, and excellent chemical character most strongly resemble the features of the Kittanning lower bed (B or Miller seam), all through southern Cambria and especially in the Paint and Shade Creek valleys of Somerset County. * * * At no place in the Blacklick region has the cement bed been noticed beneath this coal, which would identify it as bed C'. Extent and development . — This coal is often referred to as the Black- lick Creek seam. It appears above drainage level just east of Nanty Glo, on South Branch of Blacklick Creek, where it has been opened by the Ivory Hill Coal Mining Company. In the southern part of Nanty Glo are two important mines on this coal — the Pennsylvania, Beech Creek, and Eastern Coal Company’s colliery No. 14 and that of the Nanty Glo Coal Mining Company. Some distance north of the town is the mine of the Lincoln Coal Company, and still farther north, near the edge of the quadrangle, is the opening of the Cardiff Coal Company. The next mining center to the west is Twin Rocks or Expedit post- office, near which are located collieries Nos. 1 and 2 of the Big Bend Coal Mining Company and colliery No. 3 of the Commercial Coal Mining Company. Colliery No. 4 of the latter company is located about 4 miles farther west, at a little settlement called Weber. The Vinton Colliery Company controls the workings on this bed about Vintondale. Four out of its five collieries were active in the summer of 1906 and colliery No. 6 was just being opened. The coal goes below drainage level in the town and the operations to the west at Wehrum are conducted by shafting for the coal to a depth of 187 feet. On the west side of the Barnesboro or Westover Basin the bed appears above drainage level just at the edge of the quadrangle and has been worked in a small way by Id. R. Dill about a mile northwest of Dilltown. The development of this coal along Blacklick Creek is of recent date, and the production of this district, which was only 5,000 tons in 1894, had increased in 1905 to 1,045,802 tons, valued at $1,019,617. Chemical character . — The composition of this coal is indicated by analyses 17 to 27 (pp. 40-41). This exceptionally complete series of analyses shows that the Lower Kittanning (Miller) coal has much the same character along Blacklick Creek as at Johnstown and South Fork. The moisture in the coal is low, in no sample exceeding 4 per cent. The volatile matter is likewise low and remarkably uniform, ranging from more than 17 per cent to less than 19 per cent. Fixed carbon ranges from 67 to 73 per cent — a slight range considering that the samples were obtained by three individuals from scattered mines. Ash is on the whole low, but sulphur is rather high, in one sample exceeding 4 J per cent. As a whole, however, the figures all point to a high-grade coal. Steaming tests . — Steaming tests have been made on Lower Kittan- ning coal collected at Wehrum by the United States Geological Survey.® The analyses on the samples used are as follows: a Bull. U. S. Geol. Survey No. 332, 1908, pp. 201-202. 84 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Chefnical analyses of Lower Kittanning coals from Wehrum. a Test 472. Test 473. Test 467. (Moisture 1.88 2.45 3.90 23.35 64.65 Volatile matter 17.60 17. 55 8' Fixed carbon 69. 06 70.56 Ph /Ash 11.46 9.44 8. 10 [\Sulphur 5.37 3. 87 3. 11 Hydrogen : 4. 13 4.31 4.35 Carbon 75.63 78.83 78.71 Nitrogen 1. 15 1.21 1.09 Oxygen 1.94 2.00 4. 18 Ash 11.68 9. 68 8. 43 Sulphur 5.47 3. 97 3.24 a Proximate analysis of fuel as fired; ultimate analysis of dry fuel figured from car sample. (See analyses 10 and 11, pp. 40-41.) The results of the steaming tests are as* follows: Steaming tests on Lower Kittanning coal from Wehrum. Test 472. a Test 473.o Test 467. Size as used: Over 1 inch per cent. . 8.2 4.6 ^ inch to 1 inch . . . .do 11. 1 6.9 a inch to ^ inch do 19.2 13.9 Under j inch. . . .do. . . 61.5 74.6 Average diameter . . .inch. . 0.41 0.31 Duration of test hours. . 8. 75 9. 77 8. 87 Heating value of fuel B. t. u. per pound of dry fuel. . 13,729 14,240 14,258 Force of draft: Under stack damper ..inch of water.. 0. 81 0.82 0. 76 Above fire do .27 .23 .17 Furnace temperature Dry fuel used per square foot of grate surface per hour. . . °F. . 2,512 2,615 2,753 pounds.. 16.87 17.24 17.63 Equivalent water evaporated per square foot of water-heating surface per hour pounds.. 3.00 3.25 3.53 Percentage of rated horsepower of boiler developed 84.2 91.2 99.00 Water apparently evaporated per pound of fuel as fired. . Water evaporated from and at 212° F.: pounds. . 7.27 7.65 7.98 Per pound of fuel as fired do 8.76 9.22 9.65 Per pound of dry fuel do 8.93 9.45 10. 04 Per pound of combustible do 10.57 10.85 11.30 Efficiency of boiler, including grate per cent. . 62.81 64.09 68.00 Fuel as fired: Per indicated horsepower hour pounds. . 3.23 3.07 2. 93 Per electrical horsepower hour Dry fuel: Per indicated horsepower hour do 3.99 3. 79 3.62 do 3. 17 2. 99 2.82 Per electrical horsepower hour do 3.91 3.69 3.48 a Run of mine. Test 467 made on Renfro w briquets from briquetting test 176 (p. 87), which burned freely with short flame, 5.4 per cent black smoke, and very hot fire; briquets coking well and throwing off fragments of coke in ash during combustion; 39 per cent clinker, thin, metallic, red and black, brittle when cold; ash of dark-gray color, looked like coke. The figures giving the pounds of water evaporated from and at a temperature of 212° F. per pound of dry fuel used represent the value of the coal for steaming. The first two tests give 8.93 and 9.45, or an average of 9.19, which compares very well with 10.545, the figure for the first-class steaming coal from Fayette, W. Va. (See BLACKLICK CREEK DISTRICT. 85 p. 37.) The figure for test 467 (10.04) represents the steaming value of briquets and strictly speaking should not be used in making com- parisons with the results obtained from the raw coal. Coking tests . — The results of the coking tests made on this coal are given below. ° Coking tests on Lower Kittanning coal from Wehrum. [Run of mine, washed.] Test 185. Test 188. Sizfi as used . Finely crushed. 61 9,750 5,779 59. 27 262 2.69 61.96 Run of Duration of test. . Coal charged Coke produced Breeze produced . . Total yield hours. . pounds . . / do \per cent. . 1 pounds... \per cent. . do mine. 54 12,460 8,144 65.36 332 2. 66 68.02 Analyses of coal and coke. • Test 185. Test 188. Coal. Coke. Coal. Coke. Moisture 7.19 17.86 69.57 5. 38 1. 63 0. 56 .32 91. 10 8.02 1. 46 4.53 18.56 70.63 6.28 1.85 0. 57 .55 90. 23 8. 65 1.54 Volatile matter Fixed carbon Ash Sulphur The coke resulting from the first test was of a dull-gray color, soft and dense, with high sulphur. The second test, with run-of- mine coal, produced a light-gray silvery coke, much better than the coke from the finely ground coal. In the coke from the second test, also, the sulphur is high. The yield in the second test was much better than that in the first. The coal mined at Nanty Glo from this bed has been tested in beehive ovens at Gallitzin. It produced coke of good structure but of dull appearance. As in the Wehrum samples, an insufficient amount of sulphur was volatilized. The Lackawanna Coal and Coke Company has experimented with its coal about Wehrum, but the washeries have long been closed and the results of the coking tests could not be learned. The Vinton Colliery Company has recently built a large by-product plant at Vintondale and a large part of the coal mined from colliery No. 6 in 1907 was coked in it. a Bull. U. S. Geol. Survey No. 332, 1908, p. 203. 86 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Producer-gas test . — The following producer-gas test was made: Producer-gas test on Lower Kittanning coal from Wehrum. a Coal as fired. Dry coal. Combus- tible. Coal consumed in producer per horsepower per hour. Per electrical horsepower: Pounds. Pounds. Pounds. Commercially available 1. 29 1. 26 1. 12 Developed at switchboard 1. 24 1. 21 1.08 Per brake horsepower: Commercially available 1. 10 1. 07 .96 Developed at engine 1. 05 1.03. .92 Equivalent used by producer plant. Per electrical horsepower: Commercially available 1.43 1. 39 1.25 Developed at switchboard 1. 37 1. 34 1.20 Per brake horsepower: Commercially available 1.22 1.18 1. 06 Developed at engine 1. 17 1. 14 1.02 a Lump coni .— Size as used: Over 1 inch, 7 per cent; \ inch to 1 inch, 14 per cent; \ inch to \ inch, 18 per cent; under \ inch, 61 per cent. Duration of test, 24 hours. Average electrical horsepower, 191.8. Average B. t. u. per cubic foot of gas, 144.4. Total coal fired, 5,700 pounds. Analysis of gas by volumes Carbon dioxide (C0 2 ) 10. 7 Carbon monoxide (CO) 17. 2 Hydrogen (H 2 ) 1&. 8 Methane (CH 4 ) 2. 2 Nitrogen (N 2 ) 53.8 Ethylene (C 2 H 4 ) 3 Washing tests . — Washing tests were made as follows. The figures indicate that finer crushing is advantageous. The loss of “good coal ” (by which is meant all coal of a quality equal to or better than that of the washed coal) in the refuse will not exceed 2 per cent. Float and sink tests of Lower Kittanning coal from Wehrum. Percentage of float. Analysis. Number of test. Size used Specific gravity of solution used. Sink (per Ash. Sulphur. (inch). To refuse. To total sample. cent) . Per cent. Per cent reduc- tion. Per cent. Per cent reduc- tion. On raw coal (preliminary); 1 h i 1.35 72 28 5: 47 44 1.30 66 2 1. 41 78 22 5.27 46 1. 45 62 3 i h 1. 45 80 20 5.54 43 1. 54 59 4 1. 52 81 19 6.26 36 1. 71 55 On refuse (float): b 1 1. 35 11. 80 2.95 4. 95 1.71 2 1. 41 13. 20 3. 30 6.50 2. 13 3 1. 46 14 50 3. 64 7.65 2.29 4 1.51 17.20 4. 30 8.15 2.88 a For analyses of fuel used see analysis 27, p. 41. b Duration of test, 2 hours. Size as used, through 1-inch screen. Jig used, special; speed, 70 revolutions per minute; stroke, 2\ inches. Raw coal, 20.37 tons; washed coal, 15.25 tons, or 75 per cent; refuse, 5.12 tons, or 25 per cent. BLACKLICK CREEK DISTRICT. 87 Analyses. Sample tested. Moist- ure. Ash. Sulphur. Per cent. Per cent reduc- tion. Per cent. 3. 77 1. 53 19. 78 Per cent reduc- tion. Raw coal, car sample 3.13 6. 45 5.78 9.81 5. 38 47. 18 Washed coal 45 59 Refuse Briquetting tests . — Two briquetting tests were made of the coal. Test 176, with 7 per cent binder (water-gas pitch), gave satisfactory briquets, which were tough and easily handled without breaking when warm, but which were brittle when cold; they broke with characteristic smooth, glossy fracture, hard surface, and sharp edges. In test 184 the Wehrum coal was mixed with an approximately equal portion of anthracite graphitic coal from Cranston, near Provi- dence, R. I. From this mixture excellent briquets were made with 6.25 per cent binder on the Renfrow (American) machine. Although the pitch used had a low melting point, the briquets handled well from the machine and piled without stocking. The outer surface was very hard and smooth and broke without crumbling, giving a smooth fracture and sharp edges. Briquetting tests of coal frtim Wehrum. [Water-gas pitch binder.] Test Test 176.a 184.6 Test Test 176. 184. Details of manufacture: Machine used Temperature of briquets. . °F. . Binder — Laboratory No Amount .per cent. . Weight of — Fuel briquetted . .pounds. . Briquets, average do Heat value per pound — Fuel as received.. B. t. u.. Fuel as fired do Binder do Drop test (1-inch screen): Held per cent. . Passed do Renf. Renf. 185 185 4553 4543 7 6. 25 8,000 10, 000 0. 420 0.5 13, 712-j cl3, 712 dlO, 996 13, 702 12, 793 16,969 16, 966 50.5 68.5 49.5 31.5 Tumbler test (1-inch screen): Held per cent. Passed (fines) do. . . Fines through 10-mesh sieve per cent. Weathering test: Time exposed days. Condition Water absorption: In 19 days percent. In 16 days do. . . Average for first — 4 days do. . . 5 days do. . . Specific gravity (apparent) 70.5 29.5 85.0 53 e A 22.0 4. 05 i. 043 93.0 7.0 91.4 11 e A 13.3 1.90 1.275 a Size as used: Over J inch, 2.2 per cent; ^ inch to £ inch, 6 per cent; inch to ^ inch, 12 percent; & inch to 5 V inch, 19 per cent; through ^ inch, 60.8 per cent. 6 Size as used: Over i inch, 0.8 per cent; inch to \ inch, 7 per cent; inch to -fa inch, 15 per cent; 3 \, inch to inch, 22.2 per cent; through inch, 55 per cent. cCoal from Wehrum, Pa. d Coal from Cranston, R. I. «A=briquets in practically same condition as when put out. Surface shows no signs of erosion or pitting. Briquets hard with sharp edges and fracture same as that of new briquets. See Bull. U. S. Geol. Survey No. 332, 1908, p. 43. 88 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Laboratory No Air-drying loss Extracted by CS 2 : Air-dried As received Pitch in briquets, as received Extraction analyses. Pitch. 4543 per cent ....do....' do 99.66 do Fuel. Briquets. Penn- syl- vania coal. Rhode Island coal. Test 176. Test 184. 4104 3141 4913 2. 10 3.40 i 2.80 0.03 .79 .02 5.89 6. 27 .02 ! 5.72 5.02 6. 25 5.91 Occurrence and 'physical character . — In its mode of occurrence the Lower Kittanning bed on Blackliek Creek strongly resembles in its main features the same coal in the districts along Conemaugh River. (See fig. 15.) The coal is made up of a bench from 3J to 4 feet thick and of either one or two lower benches. In a few places both lower benches are missing (see sections 2, 5, and 6); the absence of both lower benches is, however, only local, for in the same mine the upper of the two has been observed at one place but has disappeared a short distance away. The lowest bench was not observed about South Fork or Johnstown but is persistent along Blackliek Creek. Here and there the main bench is underlain by bone. The middle bench is thin, averaging not more than 4 or 5 inches. The lower bench is 2 feet thick in places. The two shale partings inclosing the middle bench are thin, rarely exceeding a few inches in thickness. The analyses (see pp. 41-42) represent coal from the main bench; that from the middle thin bench is reported good but too thin to mine; and that from the lowest bench is high in ash and sulphur and usually too impure to ship. Below the lowest bench occurs a good deposit of clay, which has never been exploited along Blackliek Creek. The roof of the coal is either very firm shale or sandstone. The char- acter of the roof, the irregularity of the floor, the general absence of clay veins, and the nongaseous nature of the coal are points in which it is similar to the Lower Kittanning (Miller) bed in the Conemaugh Valley. The coal is bright and lustrous, with a marked tendency to columnar cleavage. BLACKLICK CREEK DISTRICT. 89 Figure 15.-Sections of the Lower Kittanning (Miller or B) coal in the Blacklick Creek district. Scale, 1 inch=5 feet. 1 . Pennsylvania, Beech Creek and Eastern Coal Company No. 14, Nanty Glo. 2. Nanty Glo Coal Mining Company No. 1, Nanty Glo. 3. Lincoln Coal Company, Nanty Glo. 4. Ivory Hill Coal Mining Company, Nanty Glo. 5. Cardiff Coal Company, 5 miles north of Nanty Glo. 6. Country bank \\ miles north of Nanty Glo. 7, 8. Commercial Coal Mining Company No. 3, 4 miles east of Twin Rocks. 9.’ Big Bend Coal Mining Company, Nonpareil No. 1, Twin Rocks. 10. Big Bend Coal Mining Company, Big Bend Colliery No. 2, Twin Rocks. 11. Vinton Colliery Company No. 1, Vintondale. 12. Vinton Colliery Company No. 2, Vintondale. 13. Vinton Colliery Company No. 6, Vintondale. 14. 15. Vinton Colliery Company No. 3, Vintondale. 16. Vinton Colliery Company No. 5, Vintondale. 17. Exposure in railroad cut east of Vintondale. 18. 19. Lackawanna Coal and Coke Company No. 4, Wehrum. 20. Amos Rager, Rummel Run. 21. H. R. Dill, 4 miles northwest of Dilltown. LOWER ALLEGHENY COALS. Along Blacklick Creek other coals are known which are below the Lower Kittanning bed. In the railroad cut near Twin Rocks these lower coals show, as they do also a short distance east of Weber J.ust where the spur track turns in to the collieries of the Big Bend Coal Company at Twin Rocks the following section was measured: 90 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Section of Brookville and Clarion coals (?) near Big Bend. Sandstone, massive. Coal, 10 inches Parting, 6 inches. . . Ft. in. Coal, 1 foot 6 inches ^Clarion (A')? 4 2 Parting, 4 inches . . . Coal, 1 foot Shale, black 8 Shale, sandy 2-3 Coal (Brookville (A)?) 2 Clay 3-4 Sandstone, massive. From the massive sandstones about the place where the section was made it is impossible to be absolutely sure that this coal is in the Allegheny. The massive sandstone overlying the coal in the cut may be traced northward along the nose where the river makes the big bend for some distance — in fact, so far as to make it fairly certain that it is an Allegheny sandstone and to corroborats the view that the coal whose section is given above probably corresponds to the lowest coal or coals in the Allegheny formation. One of these lower coals has been opened about 43 feet above the railroad tracks just back of Twin Rocks railroad station, but the bank is now fallen shut. The coal was reported as present only in patches and was known in the locality as the Three-foot seam or Sulphur vein. The view that the coal in the cut near Twin Rocks is in the Alle- gheny formation and at its base is strengthened by observations made on the highway and along the railroad farther west, near Weber. Near Commercial No. 4 mine the massive sandstones may be observed close below the Lower Kittanning (B) coal, and at an estimated interval of 71 to 77 feet below are found two coals thought to correspond with the coals given in the foregoing section. These are regarded, on stratigraphic grounds, as Allegheny coals, and the massive sandstone is believed to be the Kittanning sandstone member. This heavy sandstone coming at the base of the Allegheny makes it difficult to conclude as to the position of the base of this formation, especially where the evidence has to be obtained at scattered points in different sections. This massive sandstone, however, is known to occur at other places in or near the quadrangle where the relations are plain and where there is no doubt as to its being in the Allegheny — for instance, south of the quadrangle, along Stony Creek. Near Weber, as near Twin Rocks, the two coals occurring at the base of the Allegheny are too thin to be worked, each being less than a foot thick. The sections containing these two coals, regarded as the Brookville (A) and the Clarion (A') coals, are given below. The first section was measured by Mr. Martin and the second and third by Mr. Phalen. WINDBER DISTRICT. 91 Sections of Brookville and Clarion coals near Weber. 1. Section on both sides of railroad cut. Sandstone, coarse grained, thin and thick bedded Sandstone, with quartz crystals and iron ore Coal, Clarion (A 7 ?) Fire clay, blocky, fine, sandy, fossiliferous Sandstone, fine grayish Sandstone, blue-black, shaly Sandstone, fine grained, grayish Shale, bluish black, with limestone nodules Coal, Brookville (A?) Clay, grayish Ft. 19 7 2 1 4 4 in, 8 6 9 6 91 n 6 6 21 6 + 2. Section on north side of cut. Sandstone. Ft. in. Coal (bony in middle), Clarion (A 7 ) 9 Fire clay, gravelly, sandy, almost sandstone. Contains abun- dant organic impressions (fossil imprints) , but they are very poor . 5 Shale, drab or dark gray 4 6 Coal, Brookville (A) If Clay 6+ 3. Section on south side of cut. Sandstone. Ft. in. Coal, Clarion (A 7 ) 8-9 Sandstone, gnarly, or sandy fire clay with plant impressions 6 6 Shale, dark, with concretions.. 4 9 ' Coal, Brookville (A) 2 Shales, dark, irregularly bedded, upper part resembling fire clay. 4 The dip from the south to the north side of the track is marked, even for so short a distance. WINDBER DISTRICT. EXTENT. The Windber district of this report includes the territory about the town of Windber, situated within the Johnstown quadrangle. GEOLOGIC POSITION OF THE COALS. All the workable coals in this district are found in the Allegheny formation, which is above drainage level in all the hills surrounding Windber and Scalp Level. Of these coals, only the Lower Kittan- ning is now worked, but higher coals are known to be valuable. The usual main coals of the Allegheny formation are represented in this district — that is, the Upper and Lower Freeport and the Upper, Middle, and Lower Kittanning coals. These coals are also visible in the road sections in the surrounding hills. The distance between the highest and lowest of the five beds varies from 180 feet to about 210 feet, and, as usual, the Upper Kittanning bed occurs about midway between. A section of the lower part of the 92 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Allegheny was hand leveled by W. C. Phalen at Scalp Level, from the point where the trolley line crosses Paint Creek. This section is as follows: Section of lower Allegheny rocks at Scalp Level , Somerset County, Pa. Sandstone debris. Ft. in. Coal 10-12 Clay ..j, 3 Shale, sandy 5 Shale, blue 15 Coal 3-4 Sandstone, gnarly 1 Concealed, but with 1 foot of Lower Kittanning coal showing at top (railroad level) 16 Shale, black ■.. 5 Shale, sandy 10 Shale 5 Shale, debris . .^ 20 Coal, 10 inches.. . Shale, 4 inches.. Bone, 6 inches. . . Coal, 6 inches Concealed ,. 10 Sandstone, Pottsville 6+ i Brook ville or Clarion) 2 2 According to these measurements, the interval from the top of the Pottsville to the top of the Lower Kittanning (B) coal is about 70 feet, and the single coal which shows in the section may be the equivalent of the Brookville or Clarion beds. At Scalp Level, where Paint Creek passes over bluffs of the Pottsville formation, DTnvilliers a noted a thin seam of coal 14 to 18 inches thick out- cropping just above the water. This bed was not observed and may possibly be the representative of the other of these lower coals. On the assumption that the average thickness of the Allegheny from the Lower Kittanning bed to the Upper Freeport, near Windber, is 180 feet and the interval from the top of the Pottsville to the Lower Kittanning is about 75 feet, the thickness of the Allegheny in this district is about 250 feet. ALLEGHENY COALS. UPPER FREEPORT COAL. The Tapper Freeport (E) coal is the highest of the important coals outcropping in the hills surrounding Windber. It lies, according to barometric measurements, about 170 to 180 feet above the Lower Kittanning coal, and this interval remains fairly constant as far to the northeast as Elton, where drillings show it to be about 175 feet. Still farther northeast, toward South Fork of Conemaugh River, the inter- a Summary Final Kept. Pennsylvania Geol. Survey, voL 3, pt. 2, 1895, p. 2248. WINDBER DISTRICT. 93 val increases to 200 feet. West of Stony Creek, in Somerset County, according to the only available information, which has been pro- cured from diamond-drill' records, the interval is about 200 feet. Little definite information was obtained as to the thickness of the Upper Freeport coal in this district, as no openings were located on it. The diamond-drill records northeast of Windber all indicate that it is workable, containing on an average about 3 feet of coal. It is known to be persistent — a fact which, in connection with a thickness of 3 feet, seems to place it among the future sources of supply in this region. LOWER FREEPORT (d) COAL. The Lower Freeport (D) coal is also persistent in this district; but little is known about it except from data furnished from drillings. Some of the records from points northeast of Windber show it to be in places 3 feet thick; others show less promising sections. It is possible that this bed may be valuable in the future; hut the data obtained are insufficient to afford a basis for a positive opinion. UPPER KITTANNING (c') COAL. The Upper Kittanning (Cement or C') coal about Windber lies practically midway between the Upper Freeport and Lower Kit- tanning beds. This is one of the most valuable coals about Wind- i ■ m Figure 16.— Sections of the Upper Kittanning (Cement or C')coal in the Windber district. 1, Balti- more and Ohio Railroad south of quadrangle; 2, Stony Creek west of Ingleside; 3, east of Walsall; 4, .head of Walsall Creek. Scale, 1 inch = 5 feet. her. Though it is not worked on a commercial scale, something is known at least of its physical character from prospects on it in the region north of Windber, within the. limits of the Johnstown quad- rangle. In the description of this coal in the Johnstown district it was stated that it increased in thickness along Stony Creek, south- ward from Moxhom. As a matter of fact, the unusual thickness of 5 feet 6 inches prevails generally north of Windber; 6 feet has been measured one-half mile north of Eureka No. 37 and 5 feet 5 inches 1 mile north of the same mine. In both places the roof was black shale. (See also fig. 16.) 94 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Section 1 in figure 16 can not be regarded as strictly in the Windber district, as it is on the west flank of the Ebensburg (Viaduct) axis, some miles above the mouth of Paint Creek. Sections 2 and 3 are taken from country banks near Windber. Section 4 may possibly be incomplete, as two sections measured about half a mile south and less than a mile west show very nearly 5 feet of coal in one and more than 5 feet in the other. Enough is known of the coal in this district to be certain that it is of workable thickness. It may not average as thick as the above sections indicate, but an average of 4 to 5 feet in the hills north of Windber is probably a conservative estimate. Its quality is prob- ably equal to that of the coal mined from this bed near Johnstown. (See p. 40.) In places the upper part of the coal bed is bony and will have to be discarded in mining. The roof is generally very firm shale. MIDDLE KITTANNING COAL. The next lower coal, the Middle Kittanning (C), is 25 to 30 feet above the Lower Kittanning bed. A few of the diamond-drill rec- ords to the northeast of Windber show nearly 3 feet of coal in this bed. This thickness is exceptional. The coal may prove valuable in this district, but not enough is known about it to form a positive opinion. LOWER KITTANNING COAL. Name and position . — The Lower Kittanning (Miller or B) coal in the Windber district occurs, as stated above, at an interval of about 170 to 200 feet below the Upper Freeport coal along the southern edge of the quadrangle. Immediately about Windber the interval is somewhat nearer the former than the latter figure. The coal out- crops well down in the hills about the town, permitting the operations to be conducted from the outcrop by drifts. Extent and development . — The coal appears above drainage level on the eastern flank of the Ebensburg (Viaduct) anticline where this fold approaches the Wilmore Basin, near the southern edge of the quadrangle, and is present in the hills along Paint Creek westward to Stony Creek. The coal is above drainage level northward for some distance on Stony Creek, where the dip to the Johnstown Basin carries it below water level. The operations on this bed of coal in the portion of the Windber district in this quadrangle are but a small part of the coal industry around Windber. As noted above, only two operations are con- ducted wholly within the Johnstown area — namely, Eureka Nos. 37 and 40, WINDBER DISTRICT. 95 Chemical character . — Analyses Nos. 30 to 32, pages 41-42, indicate the composition of the Lower Kittanning (Miller) coal about Wind- ber. The analyses show its carbon content to be among the highest in the area, with a comparatively small amount of sulphur and ash. Occurrence and physical character . — The sections in figure 17 illustrate the general section of the coal in the Windber district. The first two are the more representative, as they are more complete, showing the under coal characteristic of the Lower Kit tanning (Miller) bed. The main bench averages between 3 Land 4 feet of coal. A small rider, averaging 3 to 4 inches in thickness but varying from 1 to 14 inches, occurs from 3J to 4 feet above the top of the main bench; it is noted in the Scalp Level section given on page 92. There is also usually present an under coal lying from 3 inches to 2 feet below the Figure 17.— Sections of the Lower Kittanning (Miller or B) coal in the Windber district. 1, Baltimore and Ohio Railroad south of quadrangle; 2, Berwind- White Coal Mining Company, Eureka No. 37, Windber; 3, near south edge of quadrangle; 4, near Walsall. Scale, 1 inch = 5 feet. main bench. This under coal ranges from 3 to 18 inches in thickness and may be very regular. The roof is excellent and is either sandstone or sandy shale. It requires little or no timbering except where broken through. The partings in the coal are the usual “sulphur” lentils or balls, which are easily separated from the coal. Rolls are numerous and here and there the coal is completely pinched out. In places the slickensided surfaces associated with thin coal indicate movement akin to true faulting. The under clay is not worked in any of the mines, so far as known. The coal in the main bench is of the lustrous columnar variety. LOWER ALLEGHENY COALS. Though lower coals occur about Windber, they are too thin to be worked so far as known. Section showing the relations of these lower Allegheny coals are given on page 24. 96 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. CONEMAUGH FURNACE DISTRICT. EXTENT. Along the west edge of the quadrangle, in the valley of Conemaugh River, the lower part of the Allegheny is brought down to drainage level by the steep dips along the western flank of the Laurel Ridge anticline. As the Allegheny or coal-bearing formation outcrops only along the river, the active mines are confined to the immediate river valley, and the district is small. Within the Johnstown area there are but two active mines — that of the Johnstown Coal Company and that of the Nineveh Coal Company. Both these concerns are working on the Lower Kittanning (Miller) bed. The dips carry this coal below drainage level just beyond the confines of the quadrangle, and farther west, in the town of Seward, it lies at a depth of 130 feet, as shown by the shaft of the Seward Coal Company. ALLEGHENY COALS. UPPER COALS. But little definite information can be given regarding the three highest coals in the Allegheny formation in this part of the quad- rangle, for the reason that they have not been worked even on a small scale and few openings on them were found. It is known, however, that they are present in the hills north of Conemaugh River, outcropping along Trout Run, on which the Upper Freeport bloom was discovered. At this place a small opening, believed to be on the Upper Kittanning coal, showed the following section: Section of Upper Kittanning coal on Trout Run. Massive shale roof. Ft. in. Coal . 1 Bony 4 Coal * 2 3£+ The Middle Kittanning is fairly persistent in this district and occurs about 40 feet above the Lower Kittanning (Miller) bed. Near Cramer this bed measured as follows: Section of Middle Kittanning ( C ) coal near Cramer. Ft. in. Shale 6 CoaL 1 8 Bony 2 Coal ’ , 11 Clay. About Seward this coal measures 2 feet 6 inches. At Seward also the Lower Freeport (D) coal is reported as being about 2 feet thick, capped by 8 to 12 feet of shales mixed with sandstone slabs and underlain by 7 feet of bluish massive shales. The overlying shales are used in the manufacture of red building brick. CONEMAUGH FURNACE DISTRICT. 97 LOWER KITTANNING (b) COAL. Extent and development . — The only coal of commercial importance around Conemaugh Furnace at present is the Lower Kittanmng (Miller) bed, and, as stated above, there are but two mines at which this coal is worked — that of the Johnstown Coal Company, on the north side of Conemaugh River, and that of the Nineveh Coal Com- pany, on the south side of the river and on the main line of the Pennsylvania Railroad. The coal here lies about 65 to 70 feet* above the top of the Pottsville formation. Farther west the coal goes below drainage level and is mined by shaft near Seward by the Seward Coal Company. Chemical character . — A sample carload of coal from this bed, col- lected and shipped by J. W. Groves, of the United States Geological Survey, from a point on the Pennsylvania Railroad 1 J miles east of Seward, Westmoreland County, has been subjected to steaming, wash- ing, coking, and briquetting tests,® so that the character and behavior of the coal in this part of the quadrangle are known. Two mine sam- ples were also collected for chemical analysis. The results of the chemical analyses are given on pages 41-42 (Nos. 33-35) and below: Chemical analyses of Lower Kittanning coal from Conemaugh Furnace district. Laboratory number. Proximate: Moisture Volatile matter. Fixed carbon... Ash Sulphur Ultimate: Hydrogen Carbon Nitrogen Oxygen Ash Sulphur Steaming tests.® Briquetting tests, b 512. 514. 198. 213. 4726 4713 4769 4885 3.50 2.79 6. 16 1.23 19.98 21.11 19.23 20. 58 67. 71 67. 79 64. 38 67. 74 8. 81 8. 31 10. 23 10.45 1.59 1.91 2.68 2.98 4. 39 4.42 4.20 4. 56 81.06 80. 25 78. 12 79. 21 1.06 1.09 1.09 1.12 2.72 3.73 2.83 1.51 9. 13 8. 55 10.90 10.58 1.64 1.96 2. 86 3.02 a Proximate analysis of fuel as fired; ultimate analysis of dry fuel figured from car sample. b Proximate analysis of fuel as received; ultimate analysis on dry basis. Only the proximate analyses are of interest in this connection, and these need but little comment. They show the usual high carbon characteristic of this coal in the Johnstown quadrangle, together with low volatile matter. The moisture is about the same as usual for this coal, though perhaps a trifle higher. Ash and sulphur are both higher than the average for this coal in the rest of the area. a Bull. U. S. Geol. Survey No. 332, 1908, pp. 216 et seq. 69516°— Bull. 447—11 7 98 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Steaming tests . — The steaming tests were not made on the coal itself but on briquets made from it, and the results are given in the table below. The weights of water evaporated from and at a tem- perature of 212° F. per pound of dry fuel used — 9.65 pounds in test 512 and 8.14 pounds in test 514 — indicate the standing of briquets made from this coal. The results should be compared with the results with first-class steaming coals given on page 37. • Steaming tests on Lower Kit tanning coal from the Conemaugh Furnace district. Duration of test Heating value of fuel Force of draft: Test512.a Test 514.6 hours. B. t. u. per pound of dry fuel. 7. 77 14,495 7.93 14, 382 Under stack damper inch of water. Above fire do. . . Dry fuel used per square foot of grate surface per hour pounds. Equivalent water evaporated per square foot of water-heating surface per hour. .do. . . Percentage of rated horsepower of boiler developed Water apparently evaporated per pound of fuel as fired pounds. Water evaporated from and at 212° F.: Per pound of fuel as fired do. . . Per pound of dry fuel do. . . Per pound of combustible do. . . Efficiency of boiler, including grate per cent. Fuel as fired: 0. 93 .19 19. 93 3.84 107.7 7. 70 9. 32 9. 65 10. 76 64.29 0. 93 .23 27. 52 4. 47 125.3 6. 54 7. 91 8. 14 9.06 54. 66 Per indicated horsepower hour pounds. Per electrical horsepower hour do. . . Dry fuel: Per indicated horsepower hour do. . . Per electrical horsepower hour do. . . 3.03 3. 75 2.93 3. 62 3. 58 4. 41 3.47 4.29 a Equal weights of briquets made from washed coal (briquetting tests 215 and 216, p. 100). b Equal weights of briquets (briquetting tests 208 and 209, p. 100). Test 512 on briquets from tests 215 and 216 (equal weights); briquets burned freely, with intense heat and no smoke; 31 per cent clinker. Test 514 on briquets from tests 208 and 209 (equal weights) ; briquets burned freely, with intense heat and no smoke; 50 per cent clinker. Coking tests . — The results of the coking tests on this coal are given below, together with analyses of the coal and resulting coke. Coking tests on Lower Kittanning coal from Conemaugh Furnace district. [Run-of-mine coal, finely crushed.] Duration of test . Coal charged Coke produced.. Breeze produced Total yield Test 179 Test 182 (raw). (washed). hours. . 68 78 ..pounds.. 13,070 11,760 ( do 8,129 7,350 (per cent.. 62.20 62.50 (pounds... (per cent. . 420 3. 21 529 4.50 do 65. 41 67.00 Test 179 yielded soft, dense coke light gray and silvery in color, with high ash and sulphur. Test 182 yielded soft, dense coke gray in color. Ash and sulphur were reduced by washing. There was no improvement in physical appearance. CONEMAUGH FURNACE DISTRICT. 99 Analyses. Test 179. Test 182. Coal. Coke. 0.30 .28 84.95 14. 47 2. 31 Coal. Coke. Moisture 3. 91 16. 35 68. 30 11.44 2. 78 6. 30 17. 04 69. 58 7.08 1.34 0.51 .58 89. 85 9. 06 1.11 Volatile matter Fixed carbon Ash Sulphur M 7 ashing tests . — Results of washing tests are given below. The figures indicate that finer crushing is advantageous. The loss of “good coal” (by which is meant all coal of a quality equal to or bet- ter than that of the washed coal) in the refuse will not exceed 2 per cent. Float and sink tests on Lower Kittanning coal from Conemaugh Furnace district: a Percentage of float. Analyses. Number of test. Size used Specific gravity of solu- tion used. Sink (per Ash. Sulphur. (inch). To refuse. To total sample. cent). Per cent. Per cent reduc- tion. Per cent. Per cent reduc- tion. On raw coal (preliminary): 1 1 1.35 83 17 4.95 53 0.93 67 2 1.42 88 12 5. 66 46 1.24 57 3 3 1.45 88 12 4. 72 55 1.02 64 4 | 1.52 89 11 6.07 42 1.09 62 On refuse (float): 1 1.35 17.20 3. 91 5.42 1.69 2 1.41 18. 50 4.20 5.69 1.69 3 1.45 19.88 4.51 6.45 2. 15 4 1.53 20.20 4.59 7.89 2.08 a Duration of test, 2f hours. Size as used, through 1-inch screen. Jig used, special; speed, 70 revolutions per minute; stroke, inches. Raw coal, 22.21 tons; washed coal, 17.25 tons, 78 per cent; refuse, 4.96 tons, 22 per cent. Analyses. Sample tested. Mois- ture. Ash. Sulphur. Per cent. Per cent reduc- tion. Per cent. Per cent reduc- tion. Raw coal, car sample 4.00 6.48 10. 21 10.54 6. 76 46.25 2.85 1.30 17.40 Washed coal 36 54 Refuse Briquetting tests . — Seven briquetting tests were made, three on raw and four on washed coal. Briquets from both the English and the Renfrow (American) machines had similar appearance, with smooth, hard surface, were very brittle, and broke with a glossy fracture and 100 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. sharp edges. The percentage of binder (water-gas pitch) seemed to have little effect on brittleness, although Renfrow briquets with 8 per cent binder were handled with less breakage. There was no noticeable difference between the briquets made from raw and those from washed coal. For analyses of coal used in briquets see page 97 (those from bri- quetting tests 208 and 209 under steaming test 514; from briquetting tests 212, 215, and 216 under steaming test 512). Briquetting tests on run-of-mine coal from Conemaugh Furnace district. [Water-gas pitch binder.) Test 198. Test 208. Test 209. Test 212. Test 213. Test 215. Test 216. Details of manufacture: Machine used Eng. Renf. Renf. Renf. Renf. Eng. Eng. Temperature of briquets 158 158 158 158 158 176 176 Binder- Laboratory number 4683 4683 4683 4683 4683 4683 4683 Amount ..percent.. 6 7 8 7 8 6 7 Weight of— Fuel briquetted ...pounds.. 3,200 4,500 8,000 6,500 6,500 6,400 3,300 Briquets, average do.... 3.52 0.451 0.457 0. 427 0.458 3.63 3.44 Heat value per pound— Fuel as received ...B. t. u.. 13,347 13,347 13,347 14, 639 14,639 14,639 14,639 Fuel as fired do 13, 198 13,981 13,981 13,896 13,988 13,988 Binder do 16,637 16,637 16, 637 16,637 16, 637 16, 637 16,637 Drop test (1-inch screen): Held . .per cent. . 74.8 19.5 26.0 23.0 19.5 74.6 71.9 Passed do 25.2 80.5 74.0 77.0 80.5 25.4 28.1 Tumbler test (1-inch screen): Held do 71.0 54.0 61.5 67.0 64.0 74.0 70.5 Passed (fines) do 29.0 46.0 38.5 33.0 36.0 26.0 29.5 Fines through 10-mesh sieve... do 65.4 86.8 86.4 91.6 87.3 63.2 70.4 Water absorption: In 13 days do 14.5 15.5 15.0 19.0 14.5 9.5 11.0 Average for first 5 days do 2.34 2. 78 2.66 3.1 2.50 1.56 1.56 Specific gravity (apparent) 1. 141 1.11 1.127 1.043 1.144 1.148 1.121 Tests 198, 208, and 209. Size used: Over J inch, 0.8 per cent; V 3 ) Magnesia (MgO) Lime (CaO). Soda (Na20) Potash (K2O) ■ Titanium oxide (Ti02)... MnC >2 . 66 5.83 Loss on ignition 99.57 99. 53 100. 26 100.00 a Total iron calculated as F« 203 . 1. Citizens’ Coal Company’s Green Hill mine. Johnstown; E. C. Sullivan, analyst. 2. A. J. Haws & Sons (Limited) mine, near the stone bridge, Johnstown; E. C. Sullivan, analyst. 3. Seward Coal Company’s mine, Seward, Westmoreland County, Pa.; E. C. Sullivan, analyst. 4. Clay underlying the Lower Kittanning (Miller) seam at Johnstown; T. T. Morrell, analyst. Second Geol. Survey Pennsylvania, Rept. H2, p. 148. This clay is worked about Johnstown by W. J. Williams at Kern- ville. Below the coal at the Kernville mine there is a shale layer of varying thickness, about 2 to 6 inches in places, below which is from 3 to 5 feet of plastic clay. This clay is mined and used at one of the local brickyards. At the Green Hill mine of the Citizens’ Coal Company the average thickness of the underlying clay is 5 feet. This also is shipped to a local brick plant. This clay is mined by A. J. Haws & Sons (Limited), both at their shaft near the famous stone bridge in Johnstown and to the west at Coopersdale. In the shaft workings an average of nearly 3 feet is worked. At Coopersdale it averages 3J feet in thickness but in places runs as thick as 5 feet. It was observed in the mine that when the clay attained its maximum thickness the coal appeared in a single bench, with its lower 4 or 5 inches bony. At both the Haws mines the Lower Kittanning coal is mined with the clay, and is used as the fuel to burn the brick at the brick plants situated at the mine mouths. The clay is also mined by Robertson & Griffith on St. Clair Run in connection with the overlying coal. Nearly all the product of the Johnstown clay mines is used at local brick plants, where it is mixed with flint clay from the Mercer horizon, shipped chiefly from South Fork and Dean station. When thus mixed with the flint clay it forms a suitable bond in a product that is used in the manufacture of high-grade refractory products and bricks for blast-furnace and open-hearth work, and in making sleeves, nozzles, tuyeres, and other articles exposed to high tempera- tures. In the most refractory products nothing but flint clay is used. CLAY AND SHALE. 119 The lowest plastic clay in the Johnstown quadrangle is associated with the Mercer coal and is not exposed immediately about the city. In the hills lying east of Stony Creek, south of Kring, on the Balti- more and Ohio Railroad, this horizon has been prospected and some clay and shale have been found, but they have never been worked. At one exposure of the Mercer south of the quadrangle, on the west flank of the Ebensburg anticlinal axis, more than 11 feet of clays and shales were measured in one exposure. Flint clay was not observed in connection with the Mercer at any of the old prospect pits. North of Sheridan, at the quarry of Bruce H. Campbell, the fol- lowing section was measured, showing 6 feet and possibly more of clay below the Mercer coal: Section of Mercer shale member at Bruce H. Cam/pbell quarry , north of Sheridan. Sandstone in massive bowlders. Ft. in. Clay, red, with rounded bowlders (Pleistocene?). 5-10 Shales * 20 Coal and bone 1 3 Clay 6 Shales 6 That the underlying clay and shales are much thicker than is indicated by the above section has been proved by sinking three test holes. Both red and buff building bricks are made from the clays and shale quarried here. SHALES. It has been remarked that the most important shale horizons about Johnstown are confined to the lower 300 feet of the Conemaugh formation. The section given on pages 115-116 shows the character of the lower 400 feet of beds in this group of rocks in a hill east of the city. From about 50 feet above the top of the Upper Freeport (Coke Yard) coal to the top of the hill numerous promising beds of shale are exposed. Most of the shale group lying between 165 and 210 feet above the Upper Freeport coal is being worked by the Johnstown Pressed Brick Company into a good building brick of both the buff and red varieties. The fuel used in burning the brick is obtained from the Upper Freeport coal, which the company works in the same hill. The shales are ground through a 12-mesh sieve, or to a size to make them “ball.” The material is then hoisted by a bucket-belt conveyor to the sieve, thence sent through a hopper to the pans, after which it is pressed into brick, the dry-press process being used. The composition of the shales employed is indicated below. The shales were first air dried and then subjected to the usual fusion, with subsequent analyses. 120 MINERAL RESOURCES OF JOHNSTOWN, FA., AND VICINITY. Ultimate and rational analyses of shales from hill east of Johnstown. 1 . 2 . Silica (Si 02 ) Alumina ( A1 2 0 3 ) Ferric oxide (Fe 2 0 3 ) 51.32 24.39 6 . 94 .14 .70 1.73 Trace. 1.43 .23 1.09 .92 11.32 64.29 17. 95 5. 74 Trace. .46 1.30 Trace. 1.64 .35 1.80 .95 5. 44 Manganese oxide (MnO) Lime (CaO) Magnesia (MgO) Sulphuric anhydride (SO 3 ) Ferrous oxide (FeO) f(Na 2 0 ) Alkahesj * ' . Water at 100° C Ignition loss Free silica 100.21 | 99. 92 10.09 81.51 8.40 28. 54 57. 85 13. 61 Clay substance Feldspathic substance 100.00 100.00 1. Sample collected from upper shale bed: see sectioa (p. 115). Analysis made at the structural-mate- rials laboratory of the United States Geological Survey at St. Louis. A. J. Phillips, analyst. 2. Sample collected from lower shale bed; see section (p. 115). Analysis made at the structural-mate- rials laboratory of the United States Geological Survey at St. Louis. P. H. Bates, analyst. * In Prospect Hill, north of Johnstown, the Cambria Steel Company has quarried shale lying about 80 to 100 feet above the Upper Freeport coal and utilized it in connection with the overlying surface clay in the manufacture of red building brick of good quality. The brick plant of the company is located at Cambria. The geologic structure immediately near Johnstown is such that the beds lie fairly flat and the lower few hundred feet of the Cone- maugh formation is exposed. Sections obtained in the hills around the city and along the Pennsylvania Railroad to the west indicate that the lower part of this formation is of prevailingly shaly charac- ter, comparable with that seen in the hill to the east. It is therefore probable that a great deal of brickmaking material exists in these hills which has never been tested. Though all this shale may not be of the grade of that worked by the Johnstown Pressed Brick Com- pany, some of it probably is, and much of it may be suitable for paving brick, sewer pipe, fireproofing of various sorts, and other rough material. All the shale in the hills about the city and to the west is fairly accessible to transportation, and cheap fuel is assured by the presence of valuable coal beds 300 feet or more below. The lowest promising shale horizon in this district is associated with the Mercer coal. The prospect pits on the Baltimore and Ohio Railroad south of Kring show the presence of dark shales at this horizon. At points north of Sheridan the Mercer shale is thick and is worked in connection with the overlying Pleistocene clays at the quarry of Bruce H. Campbell. (See PI. Y, B, p. 28.) The section on page 119 shows 20 feet of shales overlying the coal, and the thick- ness of brickmaking material at the base of the section is known from test holes put down by the company to be much greater. The shales in the 20-foot bed given near the top of the section are dark brown CLAY AND SHALE. 121 and drab in color, somewhat sandy, and concretionary. This shale is mixed with the overlying clay, and the mixture is used in making a buff or red building brick, the color depending on the proportions of shale and clay used. The beds worked at this quarry rise abruptly toward the west at a rate that soon carries the Mercer horizon with its shales over the tops of the hills. Mr. Martin collected a sample of the shale from this quarry, taking it from the entire width of the exposure and then mixing it with the overlying clay in the proportion of 2 parts of shale to 1 of clay. The sample was analyzed by P. II. Bates, of the structural-materials labo- ratory of the Survey at St. Louis, with the following results: Ultimate and rational analyses of shale and clay from Mercer shale member, B. II. Campbell quarry, north of Sheridan. Silica (Si0 2 ) Alumina ( A1 2 0 3 ) Ferric oxide (Fe 2 0 3 ) Manganese oxide (MnO) — Lime (CaO) Magnesia (MgO) Sulphuric anhydride (S0 3 ). Alkalies |^ a ^' 1k 2 o Water at 100° C Ignition loss 62. 86 18. 85 5. 19 .37 1.42 .98 . 11 .06 2. 59 2. 27 5. 45 100. 15 Free silica 27.70 Clay substance 56.41 Feldspathic substance 15. 89 SOUTH FORK DISTRICT. 100. 00 FLINT CLAY. A band of clay that occurs in the Pottsville formation in the South Fork district has been worked at points south of the Pennsylvania Railroad from South Fork westward beyond Mineral Point and also at a few places north of the railroad. In this district this clay is characterized by a persistent flinty streak. This clay is present in the hills along Conemaugh River in an area extending west to about 1 mile east of Conemaugh station. The outcrop is continuous except where the local dips and change in direction of the river carry it below drainage. The flinty clay may not be present at all points between Mineral Point and Conemaugh. For example, the clay observed at this horizon in the tunnel of the old Portage Railroad is not particu- larly flinty in character. From Mineral Point to South Fork, how- ever, the flinty character is persistent. This flint clay is now worked by the Garfield Fire Clay Company near the viaduct and by J. H. Wickes and the South Fork Fire Brick 122 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Company west of South Fork. The following section was measured at Mr. Wickes’s mine: Section of fire clay at J. II. Wickes’s mine , South Fork. Heavy sandstone roof. Ft. in. Clay, plastic 3 6 Coal f-2 Clay, flint 4 6 Sandstone. This clay was also worked by the Page-Reigard Mining Company near Mineral Point and at South Fork, but in July, 1904, the mine at South Fork was shut down. It is reported that the plastic clay is persistent but that the thickness of the flint clay is variable, dwin- dling to 14 inches in a northeast-southwest zone. A specimen of the clay was collected in October, 1906, and analyzed by A. J. Phillips at the structural-materials laboratory of the United States Geological Survey at St. Louis. This analysis (No. 1 in the table below) may be compared with an analysis of what is believed to be clay from the Mercer, taken from the central band of the bed worked years ago near the viaduct. This latter clay was not definitely fixed in its strati- graphic relations by the Platts. 0 It was regarded by them as clearly underlying all the workable coals and as being connected with the “Conglomerate Rock,” as the Pottsville was sometimes called, and as being the equivalent of the fire clay of Sandy Ridge, which is known to be in the Mercer member. The third analysis in the table repre- sents clay from the middle layer in the Sandy Ridge bed. Ultimate and rational analyses of Mercer clays. 1 . 2 . 3. Silica (Si0 2 ) 44.30 38.31 1. 40 . 10 .82 .59 Trace. .71 .22 .17 .75 12.77 45.42 36. 80 b 3. 33 d . 48 .87 . 45 44. 950 37. 750 c 2. 700 Alumina ( AI 2 O 3 ) Ferric oxide (Fe 2 C> 3 ) Manganese oxide (MnO) Lime (CaO) .302 .216 Magnesia (MgO) Sulphuric anhydride (SOs) Ferrous oxide .985 Alkalies| K2 Q } Water at 100° C Ignition loss « 12. 65 « 13. 050 Free alumina 100. 14 100 . 00 99. 953 3.88 93. 26 2.86 Clay substance Feldspathic substance 100 . 00 a Second Geol. Survey Pennsylvania, Rept. H2, 1875, p. 146. b All iron reported as peroxide of iron. c Reported “oxide of iron.” d Calculated as Mn02. « Reported as water and organic matter. 1. Flint clay from Mercer horizon, A. J. Wickes’s mine, South Fork; A. J. Phillips, analyst. Flint clay from Mercer horizon, near the viaduct; T. T. Morrell, dnalyst, Second Geol. Survey Pennsyl- vania, Rept H 2 , 1875, p. 147. 3. Fire clay of Sandy Ridge; A. S. McCreath, analyst, Second Geol. Survey Pennsvlvania, Rept. H, 1874, p. 119. CLAY AMt) SHALE. 123 There is a striking similarity among these analyses. At South Fork the clay is smooth, hard, compact, light to dark gray in color, breaks with a conchoidal fracture, and burns to a straw-yellow color. The analysis indicates a high-grade material, with perhaps a little too much iron. The clay mined at South Fork is in part shipped to Johnstown and in part mixed with plastic clay from the Lower Kittanning seam and used at the local brick plant. Some of the products of this flint clay have been tested for refractoriness at the plant of the Cambria Steel Company at Johnstown and have proved highly satisfactory. PLASTIC CLAY. About South Fork a plastic clay of doubtful value has been ob- served at a few places near the top of the Mahoning sandstone; its position corresponds with that of the band of flint clay in the Johns- town district. The clay below the Upper Freeport (Lemon) coal bed is fairly thick in this region, but it is not worked at present. At O. M. Stineman’s mine No. 3 this coal is underlain by 2 feet 3 inches of clay, which may be worked at some future time in connection with the coal. This clay is not comparable in thickness with that which directly underlies the Lower Kittanning (Miller) coal seam, and which about South Fork, as near Johnstown, is the most impor- tant plastic clay in the Allegheny formation. The plastic clay asso- ciated with the Lower Kittanning coal seam is usually workable, at some places having a thickness of 6 to 8 feet and averaging about 3 to 4 feet of workable clay of good grade. A brief note on the character of this clay will be found in the description of its occur- rence in the Johnstown district (p. 117), where analyses also are given. There is every reason to suppose that in this district it is of the same quality as about Johnstown. Most of the South Fork clay is mined in connection with the coal and is used almost entirely at the local brick plant. SHALE. So far as known the shales in the South Fork district have not been utilized. In the two large cuts west of the town of Wilmore, on the main line of the Pennsylvania Railroad, shale beds are exposed' that vary in position from 400 to 675 feet above the Upper Freeport coal. In the surrounding hills many promising shales are found conveniently situated with respect to transportation. Their appear- ance indicates that they may be adapted to the manufacture of paving brick and other materials that require only an inferior grade of clay or shale ; to determine their fitness for any purpose, however, practical tests must be made. In a recent cut opposite Ehrenfeld, along the new county road, a bed of shale 50 to 60 feet thick, lying 60 feet above the Upper Freeport coal, also appears to be promising. 124 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. BLACKLICK CREEK DISTRICT. The South Branch of Blacklick Creek flows along the northern edge of the Johnstown quadrangle. It is joined by the north branch a short distance west of Yintondale, and the main stream flows west- ward beyond the limits of the area. Deposits of flint and plastic" clay are found in the adjacent hills along the creek, and although many of these are conveniently situated with respect to lines of transportation the demand has not yet been sufficient to justify their exploitation. FLINT CLAY. The flint clay in the Blacklick Creek district occurs at two horizons. The higher is found in the lower part of the Conemaugh formation, above what is thought to be the equivalent of the Mahoning sandstone member and a few feet below a small coal bed, possibly the Mahon- ing coal. This flint clay has been observed in many places north, west, and south of Wehrum, but the rise of the beds toward the east causes a gradual increase in its distance from the valley and from transportation facilities and finally its complete absence from the hills. West of Wehrum, however, both north and south of Blacklick Creek, it occurs at many points, having in places the unusual thick- ness of 7 to 8 feet. It is a typical flint clay in appearance, though its content of iron oxide is apparently very high. A sample col- lected from a roadside exposure west of Dilltown gave the following analysis : Partial analysis of flint clay from a natural exposure west of Dilltown. [E. C. Sullivan, analyst.] Silica (Si0 2 ) 50.3 Alumina (A1 2 0 3 ) 21.3 Ferric oxide (Fe 2 0 3 ) a 10. 4 Magnesia (MgO) 61 Lime (CaO) 39 Soda (Na 2 0) 18 Potash (K,0) 1.14 Titanium oxide (Ti0 2 ) 90 Loss on ignition 12. 00 97.22 The percentage of fluxing materials, principally iron oxide, indicated in this analysis, is so high as to prohibit its practical use. A lower flint clay, lying a few feet below what may prove to be the Upper Freeport coal, was seen at a few places in the valley of Mardis Run, near the northwestern edge of the quadrangle. This clay may corre- spond to the Bolivar clay of the region to the southwest. Two feet of clay was seen at one point on the outcrop and the bed may possibly be thicker. This clay is rather remote from transportation. a Total iron calculated as FejOg. CLAY AND SHALE. 125 PLASTIC CLAY. The coal that is being extensively worked in the valley of Blacklick Creek is regarded as the equivalent of the Lower Kittanning (Miller or B) seam of the Johnstown and South Fork districts. In the Black- lick Creek district, as well as along Conemaugh River, this coal is ‘Underlain by a promising clay bed. This clay is not exploited at present, and no certain measurement of its thickness was obtained. At many of the mines 2 feet or more of promising clay was seen, comparable, in appearance at least, with that in the Johnstown district. MISCELLANEOUS LOCALITIES. Along the western flank of Laurel Ridge, near the line of the Penn- sylvania Railroad, the Lower Kittanning (Miller) coal has been opened at a few places and the clay underlying it found to be of workable thickness. At the coal mine of the Johnstown Coal Com- pany more than 2 feet of clay was seen; and near Seward, beyond the western limits of the quadrangle, 12 feet of clay occurs in the same position, 6 feet of which is worked by the Seward Brick Com- pany.® About 2 miles southeast of Conemaugh Furnace, on the main line of the Pennsylvania Railroad and south of it, the Conemaugh Stone Company has done considerable quarrying in the Pottsville and has exposed the Mercer shale member. The following section was measured but does not show the complete thickness of the clay: Section showing Mercer shale member and accompanying clays at quarry of Conemaugh Stone Company. Ft. in. Shale, dark, with 2 inches of bone near base 3 Fire clay 1 Clay, sandy 1 Clay, good, drab 1 Coal or smut Clay, drab 5+ PRODUCTION. The firms named below are engaged in the brick and clay industry in this area. In addition coal companies mining the Lower Kittan- ning coal about Johnstown and South Fork may produce small quantities of the underlying clay for use in the local brick plants. Clay miners: Page-Reigard Mining Company, flint clay, Mineral Point. W. J. Williams, plastic clay, Kernville. Citizens’ Coal Company, plastic clay, Green Hill mine, Johnstown. Robertson & Griffith, plastic clay, St. Clair Run, Morrellville. a For an analysis of the clay underlying the coal mined at Seward, see p. 118. 126 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Manufacturers of fire brick: A. J. Haws & Sons (Limited), Johnstown and Coopersdale. Hiram Swank Sons, Johnstown. South Fork Fire Brick Company, South Fork. Manufacturers of building brick: Cambria Steel Company, Johnstown. Bruce H. Campbell Brick Company, Sheridan. Johnstown Pressed Brick Company, Johnstown. BRICK INDUSTRY. The brick industry in the vicinity of Johnstown has grown to considerable magnitude. Some of the flint clay used in the manufac- ture of the fire brick and other more refractory products is shipped from other parts of the State, but except for this most of the raw material used is of local occurrence. LIMESTONE AND CEMENT MATERIALS. EXTENT. In the Conemaugh formation of western Pennsylvania numerous limestone members have been found and traced with certainty over broad areas. These have been proved to be so constant in their posi- tion in the geologic column that they have been named and have served as guides in unraveling the stratigraphy. Some of these are the Pittsburg, Clarksburg, Elk Lick, Ames or “Crinoidal,” and Upper and Lower Cambridge limestone members of the Allegheny Valley, and the Johnstown iron-ore bed, which is in places nothing more than a ferruginous limestone at an inconsiderable distance from the outcrop. Some of these limestones undoubtedly occur in the Johnstown quadrangle. Actual correlation has not been made, however, partly because the limestones in the quadrangle are regarded as lenticular and partly because they are so numerous that they can not be correlated certainly with the persistent and characteristic limestones of the Allegheny Valley. The limestones of the Conemaugh are of no importance whatever commercially and have never been used except for fertilizing pur- poses on a very small scale. The limestones in the Allegheny are of greater importance than those in the Conemaugh. They are three in number — the Upper Freeport limestone member, the Lower Free- port limestone member, and the Johnstown limestone member. UPPER FREEPORT LIMESTONE MEMBER. The Upper Freeport limestone member appears in the section only near South Fork and Ehrenfeld. A short distance east of Ehrenfeld it is exposed in some recent excavations along the main line of the Pennsylvania Railroad. It is a gray limestone from 1J to 3 feet in LIMESTONE AND CEMENT MATERIALS. 127 thickness and at Ehrenfeld it is very irregularly bedded. It lies a short distance below the Upper Freeport coal, being separated from it by about 2 feet of clay containing limestone nodules in its lower foot. So far as known, this particular limestone has never been used in this area. LOWER FREEPORT LIMESTONE MEMBER. The Lower Freeport limestone member occurs either directly below or within a foot of the base of the Lower Freeport coal, the slight interval as a rule being occupied by black shale. It ranges from 1^ to nearly 4 feet in thickness. The best exposures in the quad- rangle occur along Stony Creek (PI. IV, A, p. 24) and the Baltimore and Ohio Railroad between Moxhom and the mine of the Valley Coal and Stone Company. This limestone has never been used in any way. JOHNSTOWN LIMESTONE MEMBER. The limestone occurring below the Upper Kittanning or Cement coal is known locally as the Johnstown cement bed. It is best developed along Stony Creek and may be seen to advantage on the Baltimore and Ohio Railroad north of Kring, where it is 6 feet thick and is separated from the coal by 8 to 12 inches of shale. Along the spur track leading from the north end of the Baltimore and Ohio tunnel to the mine of the Valley Coal and Stone Company it is also conspicuous but slightly thinner. (See PI. VII, A, p. 48.) The sec- tions measured by hand level (see pp. 44 and 47) indicate the relations of this limestone and show its thickness where measured in this part of the quadrangle. The bed is nearly 8| feet thick near Conemaugh depot and nearly 5 feet in the section along the Pennsylvania Rail- road to the west, approaching Johnstown depot. To the east, on Conemaugh River, it is exposed just at the northwest apex of the first big meander. It must be thick in all the intermediate territory. Its outcrop along Stony Creek near the Rolling Mill mine of the Cam- bria Steel Company is also conspicuous. Northwest of Johnstown, near the old Cambria furnace and at the east base of Laurel Hill, it outcrops and shows just above the waters of Laurel Run. Here it is a bluish limestone with a few streaks of calcite. It is present but not very thick near South Fork, and is also reported near Scalp Level, just across the Somerset County border. In the reports of the Second Geological Survey of Pennsylvania® this bed is called the 11 Ferriferous limestone / 1 but its identity with the limestone of the same name of the Allegheny Valley was left open for more complete and harmonious evidence than was available when the report on Cambria and Somerset counties was written. a Rept. 112, 1877, pp. 150 et seq. 128 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. The limestone at this horizon was worked at one time. In the report of the Second Geological Survey, Platt mentions the Haws Cement Works as utilizing this rock occurring on Stony Creek not far from the Rolling Mill mine. He describes it as being bluish gray in color, hard, and brittle, showing small crystals of iron pyrites, and containing considerable clay. The deposit worked was dolomitic in character. The sample collected near Kring for analysis is also dolomitic in character. (See analysis 1.) Such high magnesian limestones have been used in the manufacture of natural cements near Utica, La Salle County, 111., in the Louisville district of Indiana and Kentucky, and in the Rosendale district, Ulster County, N. Y. The magnesia, in natural cements at least, may be regarded as equiva- lent to lime so far as the hydraulic properties of the product are concerned. The presence of magnesium carbonate in a natural cement rock is merely incidental, while the silica, alumina, and iron oxide are essential. For comparison average analyses of limestones from the different districts mentioned above are given below, together with that of the limestone near Johnstown: Analyses of limestones suitable for making cement. ! > 2. 3. 4. Silica (Si02) 14. 44 | 20. 92 / 13.34 18. 04 Alumina (AI2O3) 7.82 \ 3. 46 6. 18 Ferric oxide (Fe203) 1.54 2. 35 1.90 2.63 Manganese oxide (MnO) .20 Lime (CaO) 25. 05 26. 32 31. 49 25.23 Magnesia (MgO) 13. 29 12. 10 11. 19 12. 47 Sulphuric anhydride (SO3) . 15 a 1.81 b. 78 *n t fNaoO .28 | c. 18 | 36. 73 r n. d. Alkaliesj K2 Q . 86 \ n. d. Water at 100° C .28 e 37, 07 j d\. 20 \ *33.31 Ignition loss (includes CO2) 36. 48 a Average of two analyses. d Result of one analysis. b Average of five analyses. « Includes only CO 2 . c Average of two analyses, one of which is too low. 1. Sample collected on Baltimore and Ohio Railroad north of Kring. Analysis made at structural- materials testing laboratory, United States Geological Survey, St. Louis, Mo. A. J. Phillips, analyst. 2. Average of five analyses of natural cement rocks, Utica, 111. Eckel, E. C., Bull. U. S. Geol. Survey No. 243, 1905, p. 340. 3. Average of six analyses of natural cement rocks, Louisville district, Indiana-Kentucky. Eckel, E. C., Bull. U. S. Geol. Survey No. 243, 1905, p. 341. 4. Average of six analyses of natural cement rocks, Rosendale district, New York. Eckel, E. C., Bull. U. S. Geol. Survey No. 243, 1905, p. 346. The close agreement among the foregoing analyses strongly suggests that the Johnstown limestone member may be of value in the future for local use only in making natural cement. Its cementation index is 1.14, which places it in class A, according to the scheme of E. C. Eckel. 0 According to Eckel, products having an index between 1.00 and 1.15, when burned at sufficiently high temperature, are slow setting and high in tensile strength. They include the “natural Portlands ” and allied products. If not burned high enough, cements a Cements, limes, and plasters, 1905, pp. 198-199. BUILDING STONE, PAVING BLOCKS, ETC. 129 of such low index will contain free lime and magnesia. This par- ticular product near Johnstown stands near class B (in which the cementation indexes run from 1.15 to 1.60). In this class are included most American natural cements and nearly all European Roman cements. As a rule it is not necessary to burn these products at so high a temperature as those in class A. The composition of the Johnstown limestone member differs from place to place, as the following analysis of a sample collected from the vicinity of Mineral Point shows. This sample is low in alumina, magnesia, and silica and high in lime and differs from the material of the corresponding bed near Johnstown: Analysis of cement rock, Mineral Point. Sample collected by Lawrence Martin near Mineral Point. Analyzed at structural-materials laboratory, United States Geological Survey, St. Louis. A. J. Phillips, analyst.] Silica (Si0 2 ) Alumina (A1 2 0 3 ) Ferric oxide (Fe 2 0 3 ) Manganese oxide (MnO)... Lime (CaO) Magnesia (MgO) Sulphuric anhydride (S0 3 ) Aikai ies{^° Water at 100° C Ignition loss 4 . 97 2 . 57 .56 .48 48 . 36 ± 1 . 21 ± . 13 .08 .53 . 09 41 . 17 The addition of clay or shale of proper composition would be necessary to bring rock of the composition shown above to that of a Portland cement. It is almost certain that suitable clay or shale exists in the locality. The comparative thinness of the bed will militate against its extensive use. After it has been worked some time along its outcrop it will have to be mined underground. The expense attached to such operations would prevent competition except for purely local purposes. BUILDING STONE, PAVING BLOCKS, AND CONCRETE MATERIALS. The only rock suitable for building stone in the Johnstown quad- rangle is sandstone, and of this rock there is a great abundance. Locally it has proved of great value in the construction of culverts, bridges, etc., along the Pennsylvania Railroad and in the construc- tion of dwellings; but as a rule it will not bear the cost of very distant transportation. The gate at the entrance to Grandview Cemetery, Johnstown, is an example of the application of this local rock for construction purposes. The sandstones of the Conemaugh have been used in certain parts of the quadrangle in the construction of dwellings. In the north- 69516 0 — Bull. 447—11 9 130 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. eastern part the Morgantown (“Ebensburg”) sandstone member has been so used with very satisfactory results. In the hills about Johnstown the Mahoning sandstone member is exceedingly massive in places and is capable of furnishing dimension stone of sizes suit- able for the foundations of houses and for culverts, bridges, chimneys, etc. A great deal of this sandstone has been quarried from the out- crops of the Mahoning sandstone member, especially in the hills east of the city, and used for the purposes enumerated. The Pottsville formation is made up almost entirely of sand- stone. It has been quarried along the main line of the Pennsylvania Railroad and used for construction purposes and in the manufacture of concrete. The Conemaugh Stone Company formerly quarried it for use in construction along the Pennsylvania Railroad from a quarry on the south side of Conemaugh River, a few miles southeast of Conemaugh Furnace. The Pottsville formation outcrops along the Pennsylvania Railroad also near South Fork, Mineral Point, and east of Johnstown, also on the Baltimore and Ohio Railroad near Paint Creek and farther south. The sandstone is in most of these locali- ties a pure coarse-grained or gritty rock, usually weathering to a gray or gray-white rock of pleasing appearance. It seasons rapidly and firmly and withstands the eroding action of the elements in a manner to make it of great value as a building stone. West of Coopersdale the sandstones of the Pottsville formation are quarried and crushed for use in concrete. The quarry is owned by A. B. Cooper, who also controls a quarry on the Loyalhanna lime- stone member in the lower part of the hill. The limestone is crushed for use in concrete and is also used for paving blocks. The quarry on the sandstone is located a few hundred feet above the tracks of the Pennsylvania Railroad on the north side of the river. The sandstone is very pure and is decidedly coarse grained to gritty in texture. It is blasted out without much regard to the size or shape of the product, the only requirement being that the fragments be as small as pos- sible. The larger pieces are broken up and the stone is removed to the mill on the railroad by means of small cars moving on an inclined plane and controlled by a stationary engine at its foot. At the mill the sandstone is crushed by two crushers having a capacity of 100 and 300 tons a day of ten hours. It is then conveyed to a wet pan, in which it is further reduced in size and thence passed through screens of the proper size, from which it is conveyed by a bucket conveyor directly to the cars. Another rock used in the manufacture of concrete is the Loyalhanna limestone member, which (see p. 29) occurs at the top of the Pocono formation. It is about 45 feet thick in the Johnstown quadrangle. It is not a true limestone but rather a sandy limestone. It weathers GLASS SAND. 131 in a peculiar and characteristic way, well shown in Plate VI, A, page 28. This siliceous limestone is quarried and split into paving blocks which give satisfaction, and is crushed for use as ballast in rail- road beds. For both uses it is well adapted, as its calcareous portion on solution and recrystallization tends to bind the fragments solidly together and yet leaves sufficient space between them to allow the free circulation of water. The siliceous limestone exposed near the viaduct between Mineral Point and South Fork has also been quarried for paving blocks. GLASS SAND. The question has been raised whether the pure sandstone occurring in the Pottsville formation in the Johnstown quadrangle might not be used in the manufacture of glass, especially bottle glass. Sand or crushed sandstone, as is well known, is the major constituent of glass, forming from 52 to 65 per cent of the mass of the original mixture, or from 60 to 75 per cent of the .finished product. To the sand is due the absence of color (according to its purity), the transparency, brilliancy, and hardness of glass. For the finest flint ware, such as optical and cut glass, only the purest sand can be employed. For plate and win- dow glass, which are commonly pale green, absolute purity is not essential, but generally the sand should not carry more than 0.2 per cent of iron oxide. Green and amber glass for bottles, jars, and rough structural work can be made from sand relatively high in impurities, but an excess of iron is to be avoided by careful selection. Washing may be necessary to remove the iron, and magnetic separation may have to be employed. Clay in the raw material is objectionable, as it clouds the glass, but it may be removed in part by washing. Mag- nesia is troublesome because it makes the batch difficult to fuse. If a sandstone is used as a source of glass sand, it should be friable, so as to be readily crushed. The sandstone derived from the Pottsville formation is in its original form a massive rock, in some places friable but in others not; the less friable portions are, however, readily crushed. In many parts of the quadrangle the sandstone of the Pottsville fills all the requirements of a glass sand for the manufacture of bottles, jars, and rough struc- tural material; where the amount of oxide of iron is excessive it may be corrected by the addition of small amounts of manganese dioxide or other decolorizing agents. The following analysis of a sample of friable sandstone from the Pottsville formation, collected on the west flank of Laurel Ridge, not far from Seward, shows the character of this sandstone at this point, and it is quite probable that sandstone of equally great purity may be collected at other points where the Potts- ville outcrops in this area : 132 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Analysis of glass sand from Pottsville formation on westflanh of Laurel Ridge, near Seward. [Made by A. J. Phillips at the structural-materials testing laboratory of the United States Geological Survey at St. Louis, Mo.] Silica (Si0 2 ) 97. 54 Alumina (A1 2 0 3 ) 81 Ferric oxide (Fe 2 0 3 ).. .09 Lime (CaO) • i. 04 Magnesia (MgO) .06 Alkalies ^ Water at 100° C 03 Ignition loss 49 100. 24 The amount of impurities is notably small. Iron oxide falls well within the outside limits demanded for bottles, jars, and rough struc- tural material. The amount of clayey material is very small, as is also the magnesia. The sandstone of the Pottsville should offer no serious obstacle to being ground to the requisite fineness (say to pass through a 20 to 50 mesh sieve). In prospecting for glass sand only the clearest and whitest sand should be selected, and before exploitation complete quantitative analyses and furnace tests of representative samples should be made. IRON ORES. HISTORY. But one bed of iron ore in the Johnstown quadrangle deserves mention, and that one is now of historic interest only. The interest attached to the ore is, however, great, for its presence in the hills near Johnstown was perhaps the main factor in determining the location of the present great plant of the Cambria Steel Company, which sought this position for its works owing to the close association between the ore and the underlying coal beds. With the appearance of the cheap Lake ores on the market the Johnstown iron ore ceased to be of importance. At present it is not worked, and very little first- hand information is to be obtained regarding it. The following notes are simply a compilation from the report of the Second Geological Survey of Pennsylvania® and are given here to make this report of the mineral resources of the Johnstown quadrangle complete JOHNSTOWN ORE BED. EXTENT. The Johnstown ore bed is found in the center of the Johnstown Basin. Its eastern outcrop appears a short distance west of Cone- maugh depot, where it occupies a position well up on the hillsides a Rept. H2, 1875, pp. Ill, 112, 118 et seq. IRON ORES. 133 above the railroad. Thence it descends slowly westward, approaching water level at Hinckston Run, and after crossing the svnclinical axis it again rises toward the Laurel Ridge anticline and comes to the surface on the eastern flank of Laurel Ridge. In the hills along the south bank of the Conemaugh it has never been found, although repeated search has been made for it. Its horizon has been deter- mined may times and the vertical distance between it and the upper Freeport (Coke Yard) coal has been accurately measured. At Johnstown this interval is about 50 feet. This same iron-ore bed is known to exist on Mill Creek southeast of Johnstown, where it was benched for many years prior to 1875 by Dr. Schoenberger, the ore furnishing the material on which two small furnaces were run. The same ore was mined near and smelted at the old Cambria furnace, near the base of Laurel Hill. CHARACTER OF THE ORE. The ore bed at the opening of the Cambria Company’s mine on the west bank of Hinckston Run was divided into two bands by a stratum of fire clay or shale which ranged from an inch to a foot in thickness and which crumbled when exposed to the weather, losing its water slowly and changing in color. The upper bench was much richer in iron than the lower, the latter being calcareous; but the ore from both benches contained sufficient lime to flux and was charged into the furnace with the coke without limestone. The ore yielded about 30 per cent of metallic iron when carefully treated in the furnace, but sometimes ran below this figure and occasionally rose above it. Its character is expressed by the following analyses, furnished by T. T. Morrell : Analysis of iron ore from Johnstoun bed. Silica 4.885 Alumina 1. 552 Carbonate of iron 52. 330 Sesquioxide of iron 15.230 Carbonate of lime 15. 285 Carbonate of magnesia 9.390 Phosphoric acid 530 Sulphur 850 Water. Metallic iron, 35. 930. Mr. Morrell reports finding also a strong trace of manganese. The ore was calcined before being used in the furnace; the calcination was carried out in large open heaps near the mine, at an expense of about 10 per cent of fuel. The following analyses by Mr. Morrell show the general character of the ore after calcining, from both the upper and lower benches : 134 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. Analysis of calcined iron ore from Johnstown bed. Upper bench. Lower bench. Peroxide of iron 77.64 45. 86 Silica 7.34 21.94 Alumina 1.02 4.02 Sesquioxide of manganese 1.39 .86 Lime 10. 10 19. 94 Magnesia 1.01 6. 35 Phosphoric acid .99 .53 Sulphuric acid .52 .33 100. 01 99.85 Metallic iron 54. 350 32. 110 Phosphorus .424 .232 Sulphur .210 .133 PHYSICAL FEATURES OF THE ORE BED. The ore bed is invariably underlain by shale and the roof is chiefly of the same material, being locally replaced by massive sandstone containing lumps of carbonate ore. The roof shale shows a decided tendency to crumble, and after the ore has been removed it sinks steadily, gradually reducing the height of the gangways. This behavior of the roof has been a source of constant annoyance, and has required the closest watching to avoid accidents. To counteract the sinking, “ shanties” 4 feet high, consisting of strong timbers laid crosswise, are constructed at short intervals. In places these power- ful logs are crushed so tightly together as not to exceed 2 feet in height. The irregularities of the bed are perhaps one of its most striking features. These irregularities consist of 11 rolls 7 ’ and “ horse- backs,” which, though numerous, do not interfere with the general plan of working the ore. The system employed in mining is known as the long-wall method, the best and most economical of all systems wherever practicable. (See pp. 105-112.) By this method the ore is taken from along a line of wall which as it advances includes within a certain distance all the ore under the hill as far as the point reached. The ore oxidizes rapidly at the outcrop, changing from a dove color to a rich brown, the former being the color of the unaltered carbonate, the latter of the hydrous oxide, or limonite, resulting from the oxida- tion of the carbonate. The average thickness of the ore at the Hinckston Run mine is about 2 feet; it changes, however, in thick- ness abruptly, the upper band thickening and the lower thinning, and vice versa. The following measurements made at different points in the mine serve to show the varying thickness of the ore bands. The third section was measured at a distance of 10 feet from the place where the second measurement was made, and the fourth 1.5 feet still farther southwest. WATER RESOURCES. 135 Sections of Johnstown ore bed. Ft. in. I (1) Sandstone with bowlders of ore. Ore 5 Indurated fire clay 5 Ore 71 Shale. (2) Shale roof. Ore, parted by 1 inch of fire clay 2 4 Ft. in. (3) Shale roof. Ore 1 2 Shale floor. (4) Shale roof. Ore 1 Parting 4 Ore 1 Shale floor. WATER RESOURCES. The Johnstown quadrangle is a well-watered region. Most of the towns derive their water from the headwaters of the smaller creeks flowing into the main drainage channels — Stony Creek, Conemaugh and Little Conemaugh rivers, and Blacklick Creek with its North and South branches. These streams are fed by multitudes of springs as well as by the ordinary rainfall. This water is stored in reservoirs to insure a constant and adequate supply. The water is excellent, because the slopes from which most of it comes, though of small extent, are in general well wooded and comparatively free from habi- tation. The city of Johnstown obtains its water chiefly from three storage reservoirs, two on Mill Creek and one on Dalton Run. South Fork obtains its supply from a storage reservoir on Sandy Run. The town of Wehrum procures water from a reservoir on Rummel Run, and it is understood that the town of Vintondale also has a reservoir on a stream to the southeast. The town of Windber and associated mining villages, lying in part within the Johnstown quadrangle, are supplied partly from a storage reservoir on Little Paint Creek. For industrial purposes the Cambria Steel Company" has constructed a large reservoir on Hinckston Run. During most of the y"ear the flow of the streams is fairly adequate, but during the dry season of the autumn the supply" is likely to run low. During the summer of 1906 the streams all maintained a good flow of water. Away from the railroads the inhabitants of the region depend mostly on wells. Many of these wells have been driven as far down as coal beds, which are almost universally" in water-bearing zones. The water obtained from such beds is commonly sulphurous and generally considered very wholesome. Springs are very abundant but do not appear to be large. The springs generally issue from coal beds or just above impervious clay beds. Though the volume in most such springs is not large, in purity" the water can not be excelled. Many of the drill holes put down in this area have tapped water- bearing beds, but almost all the drillings have been made in search 136 MINERAL RESOURCES OF JOHNSTOWN, PA., AND VICINITY. of coal beds, and little or no attention has been paid to the water- bearing strata. These usually have been either sandstone beds or coal beds. Such a hole was drilled near the confluence of North Fork and South Fork of Bens Creek in Somerset County, near Mishler. The locality is known as Sulphur Springs. The water probably issues from the Upper Kittanning coal bed, as the drill hole is understood to be very shallow. INDEX. A. Page. C. Page. Allegheny formation, character and distribu- tion of 22-27,44 clays in 114 brick from 114 coals in. . . 22-27, 44-61, 64-78, 80-91 , 92-95, 96-101 See also 'particular coals. limestones in 126-129 sections of 22-23, 27, 92 figure showing 24 shales in 115 Alluvium, occurrence and character of 15 Ashley, G. H., work of 9 B. Baltimore and Ohio Railroad, bench marks along 14 Barnesboro syncline, description of 24 B coal. See Lower Kittanning coal. Bear Rock Run, coal at, analysis of 70 Beaverdale, coal at, section of, figure showing. 66 Beaverdam Run, coal at, section of, figure showing 66 Bench marks, location of 14 Bennington, coal at 69 coal at, analysis of 70 coking of 39 Bens Creek, coal on 49, 54 coal on, analysis of 70 section of, figure showing 55 Bens Creek (South Fork), coal on 43 Beulah Road, bench mark on 14 Big Bend, coal at 79, 81 section at 90 Blacklick Creek, coal on 22,80-81 rocks on 20 section on, figure showing 24 Blacklick Creek district, clays of. . . 113-114, 124-125 coals of 80-95 position of 79-80 extent of 78-79 Blacklick Creek seam. See Lower Kittan- ning coal. Bolivar clay member, character and distribu- tion of 25 Brick industry, firms engaged in 156 Briquetting tests, results of 87-88, 99-100 Brookvillecoal, character and distribution of. 23, 27,41-42,60-61,77-78 sections of 60,91,92 figures showing 24, 78 See also Dirty A coal. Buffalo sandstone member, character and dis- tribution of 20 section of 17 Butler sandstone member, character and dis- tribution of 25 Cambria, coal at and near 54, 55 coal at and near, section of, figure show- ing 55 Carboniferous system, occurrence and char- acter of 16-29 Catskill formation, character and distribu- tion of 29 section of 30 C coal, position of 80 See also Middle Kittanning. C' coal. See Upper Kittanning coal. Cement. See Portland cement. Cement coal. See Upper Kittanning coal. Cement rock, natural, analyses of 128, 129 Chickaree, triangulation station at 11-12 Clapboard Run, clay on 117 coal on 49, 53, 58, 59, 60 sections of 60 figures showing 50, 55, 59 section of, figure showing 24 structure near 34 Clarion coal, character and distribution of. 23, 27, 61 section of 90,91,92 'figures showing 24,61 Clay, character and distribution of 113-126 See also Flint clays; Plastic clays. Clay industry, firms engaged in 125-126 Coal, mining of, bibliography of 113 mining of, description of 102-112 figures showing 103, 106, 107, 108 occurrence and character of 35-101 Coal deposits, description of, by districts. . . 42-101 Coke Yard coal. Sec Upper Freeport coal. Coking tests, results of 72-73, 85, 98-99 Conemaugh formation, character and distri- bution of \ 16-22,43 clays in 113,114 coals in 19,20-22,43-44,62-64 limestone in 126 members of, description of ... 18-22 sandstones of 129-130 view of 20 sections of :... 16-18, 21-22, 115-116 shales in 115 Conemaugh Furnace, coal from 101 coal from , analyses of 41-42 Conemaugh Furnace district, clays of 114 coals of 96-102 extent of 96 Conemaugh River, clays on 121 coals on 49, 51, 53, 56, 57-58, 65, 67, 69, 96, 97 commerce by 9-10 description of 9, 11 limestone on 127 rocks on 15,28,29 sections of 30 figure showing 101 137 138 INDEX. Page. Conemaugh slope, coal from 49 coal from, analysis of 42 section of, figures showing 50, 59 Conglomerate rock. See Pottsville formation. Connoquenessing sandstone member, charac- ter and distribution of 27-28 Contours, structure, explanation of 30-31 Conveyor method, description of 105-112 Conveyors, description of 109-110 Coopersdale , clay at 118 coals at and near 27, 48, 51, 57, 60 section of, figure showing 59 sandstones near. . 130 section at 23 figure showing 24 Cramer, coal near, section of 96 Cupola tests, results of 73-75 Dale, coal at 52,54,56 coal at, analysis of 40, 42 sections of, figures showing 50, 52, 55 Dalton Run, clay on 117 coal on 25, 54 section of 26 sections of, figure showing 55 D coal. See I.ower Freeport coal. Devonian system, occurrence and charaeterof. 29-30 Dilltown, clay near 124 clay near, analysis of 124 coal near 79,83 section of, figure showing 89 D’Invilliers, E. V., on coals 80,82-83,92 on structure 82 Dirty A coal, analysis of 41 character and distribution of 39-40 See also Brookville coal. Drainage, description of 9-10 relation of, to structure. 10 Drainage, mine, methods of 104 Dunlo, coal at, section at, figure showing 66 E. East Conemaugh, coal near, section of, figure showing 50 section near 47 Ebensburg, triangulation station at 12 Ebensburg quadrangle, coal of 68 coal of, analyses of 67,70 Ebensburg sandstone. See Morgantown sand- stone member. E coal. See Upper Freeport coal. Economic geology, account of 35-136 map showing Pocket. Ehrenfeld, coal at and near 37, 65, 66, 73 coal at and near, analysis of 41-42, 76 coking of 38,72,74 cupola tests of 73-75 section of, figure showing 66 producer-gas tests of 76 limestone near 126-127 rocks at and near 20, 21, 25 sections at 21-22, 65 figure showing 77 shale near 123 Page. Elevations, location and height of 10-11 Elton, coals near 92 rocks near 19 Expedit post office. See Twin Rocks. F. Falls Run, coal at 58 Ferndale, coal near 52 “ Ferriferous limestone,” correlation of 127 Flint clays, analyses of 121, 122, 124 character and distribution of 113- 117, 121-123, 124, 125 sections of 115-116, 122, 125 Four-foot coal. See Upper Freeport coal. Foustwell, coal near 59, 60 section near 27 Franklin, coal at and near 51, 53, 58, 59, 60 coal from, analysis of 40, 42 coking of 39 sections of, figures showing 55,59 structure near 34 Frankstown, coal near 53 , 60 coal near, section of, figures showing 50, 57 Fulton, John, work of 43 Fye place, triangulation station on 13 G. Gallitzin, coal near 65 coal near, section of, figure showing 66 Gallitzin coal, character and distribution of. . 20, 43,64 Geography, outline of 9-10 Glass sand, analysis of 132 character and distribution of 131-132 Greenbrier limestone, character and distribu- tion of 29 Grubtown , coal at, sections of, figure showing. 50 H. Harlem coal, character and distribution of . . . 19 Haulage, methods of 104-105 Headings, character of 102 Hinckston Run, coal on 49 coal on, section of, figure showing 50 iron ore on 133 Homewood sandstone member, character and distribution of 27-28 I. Ingleside, bench mark at 14 coal near 43,57 sections of, figures showing 59, 93 Ireland, W. G., work of 73 Iron ores, history of 132, 133 location of 18, 132 See also Johnstown ore. Island Park, coal near 43 coal near, section of, figure showing 50 J. Johnstown, bench marks at and near 14 clays near - 116 coals in and near 25, 26, 35, 43, 58-59 analyses of 40,42 sections of 26 INDEX, 139 Tagc. Johnstown, coals in and near, sections of, fig- ures showing 50,55,59 rocks near 19,20,21,25 sections near 17-18, 22-23, 115-116 shales near 115 water supply of 135 See also Johnstown district. Johnstown Basin, description of 32,33 Johnstown district, clays of 113, 115-119 coals of 25,43-61 analyses of 40-42 sections of, figures showing 50, 52, 55 description of 42 shales of 115,119-121 analyses of 120,121 brick from 119 Johnstown limestone member, character and distribution of 26, 127-129 clay below 117 analysis of 117 limestone of 127-129 analyses of 128 view of 48 Johnstown ore bed, analyses of 133,134 character and distribution of. 18, 21, 126, 132-135 sections of 135 Johnstown syncline, description of 32, 33 K. Kernville , clay at 118 coals in and near 53,56,57,58 sections of, figures showing 52,59 section near 46 Kittanning sandstone member, character and distribution of 27 Kr ing , bench mark at 1 4 clay near 119 coal near 26, 28, 43, 54, 56, 58, 61 section of 61 figure showing 55 limestone near, analysis of 128 rocks near 15,26 L. Laurel Ridge, clays on 115, 116, 125 glass sand on, analysis of 132 iron ore on 133 location and occurrence of 10 rocks on * 28,29 Laurel Ridge anticline, description of 33-34 Laurel Run, coal on 57 coal on, section of, figure showing 59 limestone on 127 Lemon coal. See Upper Freeport coal. Limestone, analyses of 128,129 character and distribution of 123-129 Limestone coal. Sec Lower Freeport coal. Little Conemaugh River, structure on 34 Llanfair, coal at C9 coal at, analysis of 70 section of 77 Lloydell, coal from, analyses of 37, 70 Long-wall system, description of 105-112 figures showing 106, 107, 108 recommendation of 105 Page. Lower Allegheny coals, character and distri- bution of 39- 40, 60-61, 77-78, 89-91, 95 See also Brookville coal; Clarion coal; Dirty A coal. Lower Freeport coal, character and distribu- tion of 25, 35, 51-52, 67, 80-82, 93, 96 sections of 22,44,46 figures showing 24, 52, 81 view of 24 Lower Freeport limestone member, char- acter and distribution of 25, 127 view of 24 Lower Kittanning clay member, character and distribution of 27 Lower Kittanning coal, analyses of 36-37 40-42,58,69-70,71,73,76, 84, 85, 86, 87, 88, 95, 97, 99, 100 briquetting tests of 87-88, 97, 99-100 character and distribution of. . . 27, 34, 36, 57-60, 69, 76-77, 82-83, 88, 94-95, 97, 101 clay below 117-118,123,125 analysis of 118 coke from, analyses of 73,85,99 coking tests of 38-39, 58, 72-73, 85, 98-99 cupola tests of 73-75 producer-gas tests of 76, 86 sections of 23, 47, 48, 77, 79, 101 figures showing 24, 59, 77, 89, 95, 101 steaming tests of 70-72, 83-85, 97, 98 structure map of Pocket. explanation of 30 washing tests of 86-87, 99 “ Lower Productive Coal Measures.” See Allegheny formation. Loyalhanna limestone member, character and distribution of 29 use of, foj concrete 130-131 view of 28 M. Mahoning coal, character and distribution of. . 22, 43,64 section of 44 Mahoning sandstone member, character and distribution of 20-22 sections of 18,21-22 use of, for building 130 Map, economic and structural, of Johnstown quadrangle Pocket. Map, index, showing position of Johnstown quadrangle 9 Mardis Run, clay on 25, 114, 124 coal on 79, 80, 81, 82 section of, figure showing 81 Martin, Lawrence, work of 9 Mauch Chunk shale, character and distribu- tion of 28-29 sections of 28,29 view of 28 Mercer coal, character and distribution of 61 section of 61 Mercer shale member, character and distribu- tion of 27-28 clays of 114, 119, 121-122, 125 140 INDEX. Pago. Mercer shale member, clays of, analyses of. 121, 122 clays of, section of 119, 122, 125 quarry on, view of 28 section of 125 shale of 120-121,125 analysis of 121 Middle Kittanning coal, character and dis- tribution of 26, 44, 56-57, 82, 94, 96 sections of 79, 82, 96 figure showing 24 Mill Creek, clay on 117 coal on 51,53,54 iron ore on 133 section on 45 Miller coal. See Lower Kittanning coal. Mineral Point, coal near 67,77-78 coal near, sections of, figures showing 68, 77 view of 24 limestones at, analyses of 129 rocks near 15 Mineral Point district. See South Fork- Mineral Point district. Mineral resources, description of 35-136 Mining, facility of 10 Mississippian series, occurrence and character of 28-29 Morgantown sandstone member, character and distribution of 19 section of 16 Morrellville, coal near 54, 58 Moxhom, coal near 54,56,93 coal near, analysis of 40, 42 sections of, figures showing 50,55 limestone near 127 N. Nanty Glo, bench mark at 14 coal of 78-79,80,81-82,83 analyses of 40, 42 coking of 39 sections of, figures showing 81,89 New Germany, coal near 67 P. Paint Creek, coal near 60,94 rocks near 15,28,60-61 sandstone near 130 section near 28 Peggy s Run, coal on 51, 53, 56, 58, 60 section on, figure showing 24 Pennsylvania, cooperation with 9 Pennsylvania Railroad, bench marks along. . 14 Pennsylvanian series, occurrence and char- acter of 16-28 Phalen, W. C., work of 9 Pillars, details of 103 Plastic clays, analyses of 117,118 character and distribution of 114-115, 117-119,123,125 sections of 119 Platt, Franklin, on Summerhill mine 62-64 Pleasant Hill, clays on 116 Pleistocene deposits, occurrence and character of 15 Page. Pocono formation, character and distribution of 29 topography of 10 Portland cement, materials for 26 Pottsville formation, character and distribu- tion of 27-28 coals of 61,78 sections of 61,78 See also Mercer coal. glass sand from 131-132 analysis of 132 sandstones of 130 section of 28 topography of 10 Producer-gas tests, results of 76,86 Prospect Hill, shale on 120 Prossers Knob, coal in 43 section of 17-18 Puritan, coal at, analysis of 68 coal at, section of, figure showing 66 Q. Quaternary system, occurrence and character of 15 R. Recent deposits, occurrence and character of. 15 Red shale, character and distribution of 19, 20 Relief, description of 10-11 Rexis, coal near 80 coal near, section of, figure showing 81 River deposits, occurrence and character of. . 15 Room and pillar system, description of 102-105 Rooms, character of 102-103 Roxbury, coal at, section of, figure showing. . 50 Rummel Run, coal on, section of, figure show- ing 89 S. St. Clair Run, coal on 49-50, 58 coal on, section of, figure showing 50, 59 Salix, bench mark at 14 Salt Lick Run, coal on, section of, figure show- ing 68 Saltsburg sandstone member, character and distribution of 19-20 Sams Run, coal on 49, 52, 54, 56 coal on, sections of, figures showing. . . 50, 52, 55 Sandstone, character and distribution of. . 129, 131 use of, for building 129 Sandy Ridge, clay from, analysis of 112 Scalp Level, bench mark at 14 coals near 91,92 analysis of 41-42 limestone at 127 section at 92 Seidel, George, work of 13 Seward, bench mark at 14 clays at 114 coal at 96,97,101 analysis of 37 coking of 38,39 section of, figure showing 101 glass sand near, analysis of 132 INDEX. 141 Page. Shale, analyses of. 120, 121 character and distribution of . 113, 115,119-121,123 Sherbine farm, triangulation station on 12-13 Sheridan, clay near 114-115, 119 coal near 61 quarry near, view of 28 rocks near 15 shale near 115,120-121 analysis of 121 Shingle Run, clay on 116 Six-foot coal, analysis of 41 character and distribution of 39-40 See also Brookville coal. Solomons Run, coal on 49, 52, 54, 56, 58 coal on, analysis of 40, 42 section of, figures showing 52, 55, 57 South Fork (town), clay at 121-122, 123 clay at, section of 122 coal at and near 67, 76, 77-78 production of 69 sections of, figures showing 68, 77, 78 limestone near 126-127 rocks at and near 20, 25 section at, figure showing 24 water supply of 135 See also South Fork-Mineral Point dis- trict. • South Fork (river) coals on 35,36,64,65,70,92 coals on, analyses of 40,41-42,70 sections of, figure showing 66 dam on, view of 20 rocks on 62 South Fork-Mineral Point district, clays of . . . 113, 114, 121-123 coals of 25,62-78 position of 62 extent of 61 shales of 123 Spirit leveling, progress of 13-14 Springs, character and distribution of 135 Steaming tests, details of 70-72,83-85,98 Steaming value, comparative, of coals 37 Stony Creek, bench mark on 14 clays on 114,116 coal on and near 49, 51, 53, 54, 55, 58, 61 analyses of 40, 42, 93, 94 sections of, figure showing 52 views of 24,48 description of 10 limestone near 127 rocks on 15, 20, 25, 26, 28 sections on 44, 46-47, 48 figures showing 50 Stratigraphy, description of 14-30 Structure, representation of 30-31 Structure in Johnstown quadrangle, descrip- tion of 31-34 map showing 31, Pocket relation of, to drainage 10 Summerhill, coal near 62-64 coal near, analyses of 63, 64 section of 63 rocks near 19 Page. Summerhill sandstone member, character and distribution of 18-19 Surveys, description of 11-14 T. Ten Acre Bridge, coal at 53 coal at, section of, figure showing 55 Thomas, J. I., on mining at Vintondale 108-112 Tipples, character of 105 Topography, description of 10-14 Triangulation stations, description of 11-13 location of, map showing 11 Trout Run, coal on 68-69,96 coal on, section of 96 figure showing 66 Twin Rocks, bench mark at 14 coal at or near 80, 81 , 82, 85 , 89-90 analysis of 40, 41, 42 sections of, figures showing 81 , 89 rocks at *. 28 section at 90 U. Upper Freeport coal, analyses of 35,40,65-66 character and distribution of 25, 35, 48-50, 64-67, 92-93 coking of 35 sections of 46, 47, 65 figures showing 24, 50, 66 view of 48 Upper Freeport limestone member, character and distribution of 25, 126-127 Upper Freeport sandstone. See Butler sand- stone member. Upper Kittanning coal, analyses of . .36, 40, 54, 67-68 character and distribution of 25, 35-36, 52-54, 56, 67-69, 93-94, 96 coking of 36 sections of 26,45,96 figures showing 24, 55, 68, 93 views of 24,48 V. Ventilation, methods of 104 Viaduct anticline, description of 33 Vintondale, bench mark at 14 by-product plant at 39 coal at or near 79, 80, 81, 82, 83 analysis of. 40, 42 mining at, method of 105-112 method of, figures showing 106, 107, 108 rocks near 20 section near 79,82 figure showing 89 water supply of 135 W. Walnut Grove, coal at 54 coal at, section of, figure showing 55 Walsall, coal from, analysis of 40, 42 coal from, sections of, figures showing . . . 93, 95 Walsall Creek, coal on, section of, figure show- ing 93 Washing tests, cost of 86-87,99 142 INDEX Page. Water resources, character and distribution of 135-136 Weber, coal from 83,90 coal from, analysis of 41-42 sections at 91 Wehrum, bench mark at 14 clay near 113-114,124 coal near 22, 79, 80, 83 analyses of 37, 41-42, 84, 85, 86, 87, 88 briquetting tests on 87-88 coking tests on 38-39, 85 producer-gas tests on 86 sections of, figure showing 89 steaming tests on 83-85 washing tests on 86-87 water supply of 135 Wells, use of 135-136 Wess farm, triangulation stations on 12 Westover Basin, description of 34 Page. West Virginia, coals of, analyses of 37 W hite Ash coal. See Lower Kittanning coal. Wilmore, rocks near 18 shales near 115,123 Wilmore Basin, coals in 26 coals in, sections of, figure showing 66 description of 32-33 section in 16-17 Wilmore sandstone member, character and distribution of. 18 Wilmore syncline. See Wilmore Basin. Windber, coals near 25, 35, 91-95 coals near, analysis of 41-42 section of, figure showing 95 water supply of 135 Windber district, coals of 92-95 coals of, position of 91-92 extent of 91 O DEPARTMENT OF THE INTERIOR UNITED STATES GEOLOGICAL SURVEY GEORGE OTIS SMITH, Director Bulletin 448 GEOLOGY AND MINERAL RESOURCES OF THE NIZINA DISTRICT, ALASKA BY FRED H. MOFFIT AND STEPHEN R. CAPPS WASHINGTON GOVERNMENT PRINTING OFFICE 1911 CONTENTS. Pago. Preface, by Alfred H. Brooks 7 Introduction 9 Location and area 9 Outline of geography, geology, and exploration 9 Climate 13 Vegetation 15 Population i 16 Transportation 16 Topography 18 Relief 18 Drainage 20 Descriptive geology 20 Stratigraphy 20 Sedimentary rocks 20 Rock types 20 Triassic system 21 Chitistone limestone 21 Character of the formation 21 Distribution 22 Thickness 23 Age 23 McCarthy shale 28 Character of the formation 28 Distribution 28 Thickness 29 Age 30 Jurassic system 31 Kennicott formation 31 Character of the formation 31 Distribution 36 Thickness 37 Age and correlation 38 Quaternary system 43 Preglacial conditions 43 Pleistocene ( “ Glacial ” ) epoch 43 Character and extent of glaciation 43 Chitina glacier 45 Nizina glacier 46 Kennicott glacier 47 Retreat of the ice 48 Bench gravels 49 ‘ Present stream gravels 50 Postglacial erosion 51 Rock glaciers 52 3 4 CONTENTS. Descriptive geology — Continued. Page. Stratigraphy — Continued. Igneous rocks 60 Triassic or pre-Triassic 60 Nikolai greenstone 60 Character of the formation 60 Petrographic description 61 Distribution 61 Thickness 62 Age 63 Jurassic or post-Jurassic igneous rocks 64 Quartz diorite porphyry intrusives 64 Lithologic character 64 Petrographic description 65 Distribution 66 Age 66 Structure 67 Areal geology 70 Historical geology - 71 Sedimentary and igneous record 71 Physiographic record 74 Economic geology 75 History 75 Copper 77 Occurrence of the ores 77 General statement 77 Copper sulphide deposits in greenstone and limestone 78 Native copper associated with the greenstone 79 Placer copper 80 Origin of the copper deposits 81 Description of properties 83 Principal groups 83 Bonanza mine 84 Jumbo claim 90 Erie claim 91 Independence claims 92 Marvellous and Bonanza extension claims 92 Nikolai claim 93 Westover claim 95 Other prospects 97 Gold 98 Production 98 Source of the gold 98 Placer deposits 100 Dan Creek 100 Chititu Creek 103 Young Creek 107 Index 109 ILLUSTRATIONS. Page. Plate I. Map of the Copper and Chitina valleys, showing location of area represented on the Nizina special map 0 II. Nizina special map In pocket III. Geologic map of the Nizina district : In pocket IV. A, Talus cones on east side of McCarthy Creek at base of limestone cliffs; B, Folded Triassic limestone-shale beds on southwest side of Copper Creek 18 V. Limestone wall on west side of Nizina River near mouth of Chitistone River 22 VI. A, Bowlders in conglomerate at base of Kennicott formation on south branch of Nikolai Creek; B, Sandstone of Ken- nicott formation on ridge south of Nikolai mine 32 VII. A and B, Unconformity between Triassic and Jurassic for- mations 36 VIII. Rock glacier on McCarthy Creek three-fourths of a mile above mouth of East Fork 56 IX. A, Rock glacier near head of National Creek ; B, Head of rock glacier on Little Nikolai Creek 56 X. A, Rock glacier in a tributary of McCarthy Creek northeast of Bonanza mine ; B, Detail of surface of rock glacier on tributary of McCarthy Creek 58 XI. A, North end of Porphyry Peak, showing inclusions of black shale in porphyry ; B, Porphyritic intrusions in black shale of Kennicott formation on McCarthy Creek 64 XII. West side of ridge at Bonanza mine 84 Figure 1. Columnar section showing the formations represented on the geologic map of the Nizina district 11 2. Columnar section of the basal part, of the Kennicott forma- tion exposed on Nikolai Creek 31 3. Generalized columnar section of the Jurassic sediment in the Nizina district 37 4. Diagram showing the overlapping of lenticular porphyry sills in the black shales of Copper Creek 65 5. Sketch map of the area near the Bonanza mine, showing the limestone-greenstone contact, the location of the richer ores on the surface, and the tunnels 87 6. Sketch showing form of ore body exposed in the upper north- ern tunnel at the Bonanza mine 88 6 ILLUSTRATIONS. Page. Figure 7. Sketch showing form of ore body exposed in the southern tunnel at the Bonanza mine 89 8. Sketch of the ore body at the Jumbo claim 91 9. Sketch map of area in vicinity of Nikolai mine 94 10. Sketch map of a part of Chititu, Rex, and White creeks, showing the location of claims and the relation of bench and stream gravels 104 11. Diagram showing the method of operating hydraulic giants on Chititu Creek 100 PREFACE. By Alfred H. Brooks. The completion in 1908 of the reconnaissance surveys a of the two copper belts lying north and south of the Wrangell Mountains paved the way for more detailed investigations. As the southern or Chitina copper belt will be the first one to be developed, it was appropriate to begin the detailed investigation in this field. The funds available for this work made it possible to survey only a part of the Chitina belt, and after careful consideration it was de- cided to take up the work in the Nizina district. This conclusion was based on three considerations: (1) The information available indicated that the Nizina district afforded the best opportunities for solving the general geologic problems relating to the entire copper belt; (2) the mining developments of this part of the district were more extensive than elsewhere in the belt, which gave both better opportunities for observations on the occurrence of the ores and greater promise of soon reaching a productive basis; (3) investiga- tion of this field made it possible to cover a placer district long pro- ductive in a small way and giving promise of larger output. The descriptions set forth in this report apply to only about one- fourth of the Chitina copper belt, but the conclusions advanced as to occurrence of the ores will, it is believed, have value to the entire district. If the developments in the Chitina Valley continue, as is expected, further surveys will be undertaken as soon as circumstances permit. The cost of detailed geologic maps is much increased by the fact that they must be preceded by detailed topographic surveys. The Nizina region was surveyed by D. C. Witherspoon in 1908, and the resulting map, which is an excellent piece of work done under very adverse conditions, accompanies this report (PI. II, in pocket) and adds much to its value. a Moffit, F. H., and Maddren, A. G., The mineral resources of the Kotsina-Chitina region, Alaska : Bull. U. S. Geol. Survey No. 374, 1909 ; Moffit, F. H., and Knopf, Adolph, The min- eral resources of the Nabesna- White River district : Bull. U. S. Geol. Survey No. 417, 1910. 7 8 THE NIZINA DISTRICT, ALASKA. The general geology of this district as set forth in the report bears testimony to the accuracy of the observations and deductions of the earlier workers in this field. It is a significant fact that the strati- graphic subdivisions, suggested by Oscar Rohn, who did the pioneer work in this field, have found acceptance in the present analysis of the geologic sequence. The most important conclusion bearing on the economic geology here presented is the fact that the copper-ore bodies appear to occur chiefly along a system of cross fractures which are at approximately right angles to the greenstone-limestone contact. These fractures occur along well-defined faults, at least one of which has been traced for a long distance. This may apply to the entire Chitina district and is worthy of consideration by the prospector. These investigations also appear to indicate that the copper depos- its are by no means confined to the immediate vicinity of the lime- stone-greenstone contact, as has usually been supposed. Though the most promising ore bodies thus far found do occur in this contact, evidence of strong mineralization has been found at a considerable distance from it. Another important fact brought out by this inves- tigation is the occurrence of auriferous deposits in the Kennicott formation (Jurassic). This report, although far more complete than any other report pre- viously published on the district, is b}^ no means exhaustive. With the progress of mining many facts will be ascertained which will make possible more definite statements on the geology of the mineral deposits. If the district develops into a great copper producer, a detailed study of the mining geology should be undertaken similar to those made of many of the mining camps of the Western States. U . S. GEOLOGICAL SURVEY BULLETIN 448 PLATE I MAP OF THE COPPER AND CHITINA VALLEYS, SHOWING LOCATION OF AREA REPRESENTED ON NIZINA SPECIAL MAP. •TIN 448 PLATE GEOLOGY AND MINERAL RESOURCES OF THE NIZINA DISTRICT, ALASKA. By Fred H. Moffit and Stephen R. Capps. INTRODUCTION. LOCATION AND AREA. The Nizina district takes its name from Nizina River, a northern branch of Chitina River, and lies in the eastern part of the Copper River drainage basin. Its position with reference to the coast and the Canadian boundary is shown on Plate I, opposite. That portion of it to which the following descriptions are confined is included between parallels 61° 12' and 61° 37' north latitude and meridians 142° 22' and 143° west longitude and is represented on the Nizina special map. (See PI. II, in pocket.) The area mapped, however, is irregular in outline and only 300 square miles in extent, so that it comprises little more than one-half of the quadrangle indicated. OUTLINE OF GEOGRAPHY, GEOLOGY, AND EXPLORATION. Chitina River rises in the high snow-covered mountains northwest of Mount St. Elias and adjacent to the international boundary line and flows westward between the Chugach and the Wrangell moun- tains till it unites with Copper River at a point 100 miles from the coast. (See PI. I.) Most of its waters, however, are derived through its northern tributaries from the snow fields of the Wrangell group. Nizina River is the largest of these tributaries. It drains the south- eastern part of the Wrangell Mountains and a small part of the area between Chitina River and the head of White River. From its prin- cipal source in Nizina Glacier it flows southward for 15 miles and then turns abruptly to the west and continues in that direction 20 miles farther before joining the Chitina. It therefore has a length of 35 miles, all minor curves and irregularities of its course being disregarded. The big westward bend of the river lies almost in the center of the area covered by the Nizina special map. 9 10 THE NIZINA DISTRICT, ALASKA. The two branches of the Nizina, with Chitistone and Kennicott rivers, contribute much the greater part of its waters. It is there- fore chiefly of glacial origin. All these streams are swift and heavily laden with glacial debris. They have floored their val- leys with broad gravel flats, over which they migrate from side to side, sometimes in a single channel, sometimes in a network of chan- nels, and, besides building up their flood plains by the addition of new material, they are continually cutting away and redepositing the material already laid down. The principal small streams shown on the Nizina special map are McCarthy Creek, a tributary of Ken- nicott River, and Dan, Chititu, and Young creeks, eastern tribu- taries of Nizina River. Their valleys do not show such profound glacial erosion as the main streams, for the ice masses that occupied them were smaller, yet they nevertheless underwent extensive glacia- tion. All are characterized by broad, open valleys at their heads and by rock canyons in their low T er courses. The Wrangell Mountains, although a more or less distinct group, merge into the St. Elias Range on the southeast and are not there sharply defined from them. They are limited on the south and west and partly on the north by the valleys of Chitina and Copper rivers, and are separated from the Nutzotin Mountains on the north- east by a depression extending from the head of Copper River to the head of White River. The group trends in a northwest-southeast direction and its length is approximately double its width. Its greatest diameter is about 100 miles. Half a dozen or more peaks of unusual beauty and size, ranging in height from 12,000 to 16,200 feet, rise above the rugged snow-covered mass about them, and from one of these, Mount Wrangell, the group received its name. The Wrangell Mountains were formed by the erosion of a great mass of Tertiary and Recent lavas piled up on an older surface of very considerable relief and having its greatest development in the neigh- borhood of Mount Wrangell and Mount Sanford. The southeastern limit of these younger flows is probably somewhere in the vicinity of Skolai Pass and Chitistone River, although it is possible that they may extend still farther to the east. Thus the Wrangell Mountains consist essentially of lava flows and are distinct in their origin from the other mountains about them, all of which are made up principally of deformed sedimentary beds. The area shown on the Nizina special map is on the border line between the volcanic flows of the Wrangell Mountains on the northwest and the older sedimentary formations of the Chugach and St. Elias mountains on the south and southeast, but the rock formations developed in the area are mostly of sedimentary origin. INTRODUCTION. 11 Conglomerate. Shale and sandstone. Conglomerate. Unconformity. ^ r^-r-rr— Interbedded shale s and limestone. The formations represented on the accompanying geologic map (PI. Ill, in pocket) are shown in the section forming figure 1. At the base is the Nikolai greenstone, made up of a great but unknown thickness of basaltic lava flows, many of which are amygdaloidal. On the top of these flows rests the Chitistone limestone, which was deposited without any interruption of structural uniformity between it and the underlying rocks. Its thickness exceeds 3,000 feet. The lower part of the Chitistone formation con- sists of thick, massive beds of gray lime- stone, but toward the top the limestone beds become thinner and small shale beds appear in increasing amount till they finally pre- dominate. The Chitistone limestone thus passes by transition through thin-bedded shales and limestones into a black shale with only occasional thin limestone beds. Much of the shale was removed by erosion before the deposition of the succeeding for- mation, so that its thickness, though in doubt, can not be less than several thousand feet. Both the Chitistone limestone and the conformably overlying shales (McCarthy shale) are of Upper Triassic age. A period of uplift and erosion took place after the Triassic black shales were laid down and was not terminated till Upper Jurassic time, when deposition began once more. On the upturned edges of' the Nikolai greenstone, the Chitistone lime- stone, and the overtying Triassic shales a great thickness of Upper Jurassic sedi- ments (Kennicott formation) was deposited. They consist of conglomerate, sandstone, and black shale, but the shale predominates greatly over the conglomerate and the sandstone. The Jurassic sediments attain a thickness of at least 7,500 feet. They are the youngest of the bed-rock formations exposed within the mapped area. The later deposits consist of Quaternary sands, gravel, and silt, most of which are intimately connected in origin with the recent glaciation of the country. The Nizina district has been the scene of igneous activity from Paleozoic time to the present. A great quantity of quartz diorite porphyry in the form of sills and dikes was intruded into the Jurassic rocks, but for some reason these intrusives rarely appear in the underlying formations. In some places the porphyritic intrii- Basaltio lava flows. Figure 1 . — Columnar section showing the formations rep- resented on the geologic map of the Nizina district. 12 THE NIZINA DISTRICT, ALASKA. sives are so extensively developed that they predominate over the shale, and the shale appears only as great black masses caught up in the light-colored intrusive rock. Folding in greater or less degree has taken place in all the forma- tions mentioned, but is far more pronounced in the older ones, par- ticularly the Triassic shales, than in the Jurassic sediments. Within the area of the Nizina special map the greenstone, limestone, and shale formations dip rather steeply to the northeast. The Jurassic rocks, on the other hand, are tilted to the southwest or lie in broad, flat folds. All have been faulted and show local displacements of very considerable extent. The earliest references to the geology of the Chitina Valley are found in the accounts of exploring expeditions made by Allen in 1885 and by Schwatka and Hayes in 1891. Such accounts, from the nature of the expeditions, could give only very incomplete informa- tion. The investigations by Rohn in 1899, however, laid the foun- dations of our present knowledge of the geology of the region. He recognized the formations that have been described and proposed the names Nikolai, Chitistone, and Ivennicott. He also applied the name McCarthy Creek shale to the shale formation overlying the Chiti- stone limestone; but this was not adopted by Schrader and Spencer in their later work, since they believed that the shale should be divided into a number of formations.® In 1900 Schrader and Spencer carried on a much more extended investigation of the geology and mineral resources of the Chitina Valley, and at the same time a topographic reconnaissance map was made by Gerdine and Witherspoon which was used as a base for the geologic map. Two years later (1902) Mendenhall visited the Kot- sina and the Elliott Creek copper prospects, in the western part of the Chitina Valley, and published also some brief statements concern- ing the Nizina gold placers, although he had no opportunity to examine them in person. No further geologic work in the Chitina region was undertaken by the Federal Government till 1907, when interest in the copper resources of the country led to an examination by Moffit and Maddren of all the copper prospects in the valley, which resulted in some additional information concerning its oreolosrv and the occurrence of both copper and gold. The importance of the district led to the preparation of the Nizina special map by Wither- spoon in 1908 and to the detailed geologic investigations in 1909, whose results are described in this report. Many notes on the copper prospects, particularly the Bonanza mine, have appeared in the daily press and in mining magazines, and although most of them had only a temporary value as news a ° Schrader, F. C., and Spencer, A. C., The geology and mineral resources of a portion of the Copper River district, Alaska: Special publication U. S. Geol. Survey, 1001, note at bottom of page 32. INTRODUCTION. 13 few are permanent contributions to the literature. An incomplete list of papers on the district follows : Allen, Lient. Henry T. Report of an expedition to the Copper, Tanana, and Koyukuk rivers, in the Territory of Alaska, in the year 1885. Washington, Government Printing Office, 1887. Hayes, C. Willard. An expedition through the Yukon district : Nat. Geog. Mag., vol. 4, 1892, pp. 117-162. Rohn, Oscar. A reconnaissance of the Chitina River and Skolai Mountains : Twenty-first Ann. Report U. S. Geol. Survey, pt. 2, 1900, pp. 393-440. Schrader, Frank C., and Spencer, Arthur C. The geology and mineral resources of a portion of the Copper River district, Alaska : Special publication of the U. S. Geol. Survey, 1901. Mendenhall, Walter C., and Schrader, Frank C. The mineral resources of the Mount Wrangell district, Alaska : Prof. Paper U. S. Geol. Survey No. 15, 1903. Mendenhall, Walter C. Geology of the central Copper River region, Alaska: Prof. Paper U. S. Geol. Survey No. 41, 1905. Moffit, Fred H., and Maddren, A. G. The mineral resources of the Kotsina and Chitina valleys, Copper River region : Bull. U. S. Geol. Survey No. 345, 1908, pp. 127-175. (This is a preliminary statement of results published in a more complete form in Bulletin 374. Keller, Herman A. The Copper River district, Alaska : Eng. and Min. Jour., vol. 85, No. 26, June, 1908, pp. 1273-1278. Moffit, Fred H., and Maddren, A. G. The Kotsina-Chitina region, Alaska : Bull. U. S. Geol. Survey No. 374, 1909. The field work on which the present report and the geologic map are based was done between July 1 and September 10, 1909, or in a little less than seventy days. It was greatly aided by a previous knowledge of the region and by the earlier work of Schrader and Spencer, but the time available was too short to permit an excursion up Nizina River to determine the relation between the Triassic and the Paleozoic sediments on Skolai Creek, or to make a careful study of the Kennicott formation south of Young Creek. Both localities merit careful investigation because of the light they may throw on the stratigraphy of the region. The chapter in this report dealing with the Quaternary system was written by Mr. Capps, who also did the office work on the geologic map. The task of preparing the remainder of the description of general geology and of economic geology fell to the senior author. CLIMATE. The climate of Chitina Valley is pleasanter in many ways than that of the Pacific coast region of Alaska. Temperature variations are far greater, but the precipitation is less and the number of cloudy, disagreeable days is very much smaller. No continuous records of temperature and precipitation are at hand, and it is probable that none have been kept, although observations for parts of several years have been made at Kennicott and were made available through the kindness of Mr. Stephen Birch. 14 THE NIZINA DISTRICT, ALASKA. The Copper River region, of which Chitina Valley is a part, as has been stated previously, is separated from the Pacific coast by a broad belt of mountains nearly 50 miles across and ranging in height from 6,000 to 10,000 feet. This belt is broken only by the narrow canyon-like valley of the lower Copper River, and by its influence on the warm moisture-laden air of the Pacific it becomes an important factor in the climate of Copper and Chitina basins. Another factor of importance is the still loftier Wrangell group of mountains on the north. The seasons of Copper River basin are a long winter and a short summer, separated by a still shorter spring and fall. Spring comes sooner in the upper Chitina Valley than in the Copper River valley proper, as is shown by the earlier breaking up of the ice. Snow goes from the valley bottoms by the middle of May and from the lower hills by the first of June, but enough remains on the mountain sides till the first or middle of July to hinder prospecting. The summer climate resembles that of some of our Northern States in late spring. Frosts are not expected from the middle of June to the middle of July, but by the first of September the snow line begins to descend on the mountain sides. After the spring break-up the volume of water in the streams, particularly those fed by snow fields and glaciers, gradually increases until it reaches a maximum about the middle of July; it then decreases rapidly as the cooler nights come on. The July period of high water is not the result of increased pre- cipitation but of the warm weather and the bright sun on the snow fields. Cloudy da}^s alwaj^s make a very appreciable difference in the daily rise of the glacier streams. Sometimes, however, the rivers are flooded by unusually heavy rains and occasionally in winter by the breaking out of water confined in the glaciers. This took place in the Kennicott Glacier early in 1909. During a period of unusually cold weather the outlet of the subglacial stream known as the “ pot- hole ” was closed and the water backed up under the glacier till the pressure was so great that the ice could not resist it. The water burst forth from a new outlet and flooded the Kennicott and Chitina rivers, tearing up the ice and piling it in confusion. Fortunately no one was freighting on the river, and the new ice which formed afterward gave the best sledding ever known by freighters on the Chitina. A similar flood caused by the breaking out of confined waters from Nizina Glacier took place a few years previously. The high water of July makes the fording of Nizina River difficult and at times dangerous, but this difficulty decreases in August, and by the first of September it is ended. Temperatures low enough to allow standing water to freeze are usual in the latter part of August, and early in September the glaciers cease to be active and the streams are clear and low. INTRODUCTION. 15 Temperatures of 30°, 40°, or even 50° below zero are experienced in winter, and the snowfall is heavy, although much less than on the coast. Observations at Kennicott, at the mouth of National Creek, and at the Bonanza mine, a little more than 2^ miles away and 4,000 feet higher, showed that the temperature at the mine during the cold- est weather was always considerably higher than at the lower camp. The winter of 1908-9 was unusual because of its low temperatures and light snowfall. It resulted from these conditions that the streams were in places frozen to the bottom, and the water, breaking out above, ran down over the top and froze to a great thickness. Some of the so-called glaciers on Chititu Creek had a thickness of 15 or 20 feet and did not melt a^ay till early in the following July, thus seriously interfering with placer mining. Such conditions are common enough in the streams of northern Alaska but are unusual in the Nizina district. VEGETATION. In this region, as in many other parts of Alaska, vegetation flour- ishes in a way that would be surprising to those who think of the country only as a region of continual cold and ice. The growing season is short, but the summer days are warm and much longer than in lower latitudes, so that in the few favorable weeks plants grow rapidly. Grass comes up as soon as the snow goes and by the first or middle of June there is good feed for horses in favorable places. It is not abundant in the lower valley bottoms, even in midsummer, and the best of it is found at or above timber line. There is good feed in the upper part of all the small valleys. A small leguminous plant, locally called “ pea vine,” grows on the gravel bars and in the fall and late summer makes excellent forage. It is nourishing, and horses are so fond of it that they will leave almost anything else to get it. Grass loses its nourishing qualities as soon as the frost strikes it, and for this reason miners and prospectors start their horses to the coast about the first of September. All the lower mountain slopes of the Nizina district and all the valley bottoms except the flood plains of streams are covered with spruce timber. The upper limit of timber ranges from 2,500 to 4,000 feet above sea and is highest on the gentle and rounded slopes away from the glaciers, such as the south slope of the ridge west of Rex Creek and on Sourdough Hill. Timber suitable for lumber grows on the lower ground. The best of it is found on the flats south of Nizina River, from Dan Creek to Young Creek, in the drier ground at the base of the hill slopes. Some of the trees reach a diameter of 18 inches and are tall enough to furnish two 16-foot cuts. Be- sides the spruce, there are cottonwood and birch, but these have 16 THE NIZINA DISTRICT, ALASKA. little value for lumber. A heavy growth of alders is usually found about timber line. Willows are present in the valleys, but are far less abundant in variety and amount than in northern Alaska. The “ devilclub,” so troublesome in the coast region, is found occasionally in the Nizina district also. POPULATION. During the early days of the Nizina gold excitement the white population of the district amounted to several hundred persons, but this number quickly decreased, asns usual in such stampedes. There are no accurate records of the number of early comers. Some of them were of the “ hanger-on ” class and stayed only long enough to learn that the district had little to offer them. The later population has been a variable one, but for the last two or three years it probably has not been far from 100. Most of this number were employed in the gold placers of Chititu and Dan creeks and the rest were pros- pecting for copper. With the completion of the railroad and the beginning of mining at Kennicott and the increased activity in the gold-producing streams that will come with better transportation the white population will increase. There is no permanent native population. Nizina River valley was the hunting ground of Chief Nikolai, and his house was near the mouth of Dan Creek, but since hffe death several years ago superstition has kept his followers from returning there until within the last two summers. The perma- nent dwellings of the Indians are on Copper River, where they spend most of the winter and where they fish in summer. It seems to have been the custom of many to leave the fishing ground only during the time of the fall hunting or in the trapping season. TRANSPORTATION. To provide satisfactory means and routes of transportation has been from the beginning the most serious difficulty the prospectors in Chitina Valley have had to meet. Up to the present time all supplies and equipment for the Nizina district have been brought from Valdez in winter by sled. The route usually followed in freighting is from Valdez to Tonsina over the Government trail, then by way of Tonsina, Copper, Chitina, and Nazina rivers to the desti- nation. Occasionally, however, this route has been varied by cross- ing Marshall Pass at the head of Lowe River and following Tasnuna and Copper rivers to the mouth of the Chitina ; but this latter route was given up because of the difficulties encountered on Tasnuna River and of the fact that the Government trail to Fairbanks is kept open all winter by the regular travel. The great advantage of the route lay in the ability to haul very heavy loads on the INTRODUCTION. 17 smooth ice of Copper River, thus saving time and horse feed, the two great items of expense, on this part of the trip. This route prob- ably would have been used exclusively for freighting to Chitina Valley if a good trail down Tasnuna River had been available for travel. The time consumed in carrying large outfits from Valdez to the Nizina district is from two to three months. The cost of freighting has varied from slightly less than 7 cents to 30 cents per pound, de- pending on the size of the outfit and the condition of the trail. The lower figure of cost is an exceptional one and is not possible under any other than the most favorable conditions. Probably about 10 cents per pound is an average cost for the larger companies when the trail is good. Summer travel is over a route different from that followed in winter. The summer trail leaves the Government trail at Tonsina and crosses Copper River at the mouth of Tonsina River. From there it passes to the north side of Chitina Valley, entering the moun- tains by way of Kuskalana River and crossing Kuskalana and Fourth of July passes to Ivennicott Glacier and River. No freighting is done on the summer trail, but the mail goes in over it twice each month. Within the Nizina district trails connect the various camps and enable the miners to travel from one to another without serious diffi- culty, although there is little communication between them during the working season. The trails are all shown on the topographic map and need not be described in detail. The one most traveled is that over Sourdough Hill from McCarthy Creek to Chititu and Dan creeks. Because it is less swampy, it is used by many in preference to the lower trail around the west end of the hill, but the hill is steep and the climb is hard. One great difficulty with this trail is the necessity of fording Nizina River. A proposal to bridge the river at a point several miles below the present fording place will probably be carried out in the near future. It is seen from the figures previously given that the cost of trans- portation is a heavy tax on all work done in the Nizina district. This expense has not only hindered copper prospecting but has de- layed the installation of placer mining machinery also. This bur- den will be much lightened in a short time, however, for railroad communication with the coast is promised early in 1911. Construc- tion work on the Copper River and Northwestern Railway was commenced under the present management at Cordova in 1908 and since that time has been pushed as rapidly as conditions permitted. In 1908 the tracks were advanced from Cordova to within 10 or 12 miles of Abercrombie Rapids, although the lower steel bridge over Copper River was not erected till the following spring. In 1909 the piers for a second bridge, at the river crossing between Childs 70648°— Bull. 448—11 2 18 THE NIZINA DISTRICT, ALASKA. Glacier and Miles Glacier Lake, were built and the tracks were ad- vanced to Tiekel River. With the completion of this part of the road most of the slow and difficult work was ended and there re- mained only 90 miles of track construction to reach Kennicott. This includes a third bridge over Copper River, between the mouths of Chitina and Kotsina rivers, where it is proposed to place a tempo- rary pile bridge while the construction of piers for the permanent bridge is going on. The building of the railroad has not involved any unusually difficult construction problems for modern railroad engineering, and the greatest obstacles to operation will doubtless arise from weather conditions. Along Copper River the tracks are particularly exposed to obstruction by snowslides, and adequate, pro- vision for their protection will have to be made. Above Abercrombie Rapids the tracks follow the river bank on the debris-covered edge of Baird Glacier. The ice is overlain by a thin coating of loose rock and is overgrown with alders. It appears to have no motion, but it is probable that more or less melting goes on and that the tracks will require more attention and repair than in other places. Some have expressed uncertainty concerning the effect of the terri- ble winter winds that sweep down the lower part of Copper River valley and have even predicted that they would prevent the running of trains, but such difficulties have been overcome elsewhere and prob- ably will be here. Railroad communication with the coast promises greater aid in the development of the Copper River valley than any other single enterprise yet undertaken. TOPOGRAPHY. BELIEF. The Nizina district has been described as situated at the south- eastern border of the Wrangell Mountains, in the region where this group merges into the Coast Range Mountains to the east and south. The mapped area does not extend far enough north or east to take in any of the larger snow fields or glaciers or to include the highest mountains of the Wrangell group or Coast Range, although peaks of 7,000 or 8,000 feet are shown. To the southeast is the broad low- land formed by the junction of Chitina and Nizina valleys. The map' (PL II, in pocket) shows as the major features of relief two mountain areas separated by the valley of Nizina River, but other topographic forms are even as striking as these, particularly the steep, straight valley Avails, the deep gulches tributary to Young Creek, and the peculiar Avormlike rock glaciers. Three geologic elements are involved in the relief — the high moun- tain masses, the gravel-covered lowlands, and the gravel benches or terraces. Glacial erosion and the character of the rock formation have U. S. GEOLOGICAL SURVEY BULLETIN 448 PLATE IV A. TALUS CONES ON EAST SIDE OF McCARTHY CREEK, AT BASE OF LIMESTONE CLIFFS. See page 1 9. B. FOLDED TRIASSIC LIMESTONE AND SHALE BEDS ON SOUTHWEST SIDE OF COPPER CREEK. See page 28. TOPOGRAPHY. 19 been strikingly effective in giving form to the mountains. The work of the ice in straightening and steepening valley walls is conspicuous on Chitistone River and the adjacent part of Nizina River and on the upper part of McCarthy Creek. It is also seen in the numerous cirque valleys in which most of the streams head. McCarthy Creek is a typical example of a glaciated valley in this district. Its upper part is a broad, open, U-shaped valley with gravel floor. Its lower part is a succession of rock canyons with high gravel terraces. These features, except the gravel terraces, are characteristic of every glaciated valley of the region and are probably the result of rapid head valley glacial erosion and the effort of the stream to establish a more advantageous grade after the melting of the ice. Different kinds of rock were affected in different degrees by the glacial ice and by subsequent erosion. The massive Chitistone lime- stone forms precipitous cliffs and tall spires, as on Dan Creek, Chiti- stone and Nizina rivers, McCarthy Creek, and at Bonanza mine. The greenstone slopes are not so steep and are more uniform in sur- face contour; they rarely form perpendicular walls such as are com- mon in the limestone exposures. The shales give smooth, rounded outlines where they have undergone glacial erosion and sharp, jagged peaks and ridges with steep, bare slopes where they have been sub- jected to attack by weather alone. These two features are seen in the shale area south of Dan Creek. Between Dan Creek and White Gulch the shale mountains are characterized by angular outlines and bare slopes, but south of Chititu Creek the same shales were over- ridden by the ice streams from Chitina Valley and present smooth, rounded contours. This feature, however, has been modified by intense postglacial erosion, with the production of such topographic forms as Blei Gulch and the deep gashes cut by tributaries of Young Creek. A different topographic form, dependent on the structure of the upper shale formation, is the flat top of the ridge on the west side of Nizina River directly opposite the mouth of the Chitistone. It is due to the almost horizontal position of the sandstone beds that form the base of the Kennicott in this locality. Talus deposits cover the lowest mountain slopes and reach their greatest development at the bases of large porphyry exposures and limestone cliffs. In this connection it should be said that the occur- rence of a small proportion of porphyry in talus slopes and rock glaciers is usually sufficient to obscure other kinds of rock. Talus fans of noticeable symmetry have been built up below gulches in the limestone formation east of McCarthy Creek (PL IV, A) and north of Chitistone River. The peculiar detrital accumulations here called rock glaciers are confined to the high mountainous parts of the district but are widely distributed in the mapped area. They are described in the discussion of Quaternary deposits. 20 THE NIZTNA DISTRICT, ALASKA. The second important element in the relief of the district is the gravel-covered valley lowland areas. Their distribution is readily seen on the map. They represent the accumulated deposits of present glacial erosion and the reworked deposits of former glaciation, to- gether with the contributions of present stream erosion. With the older bench gravels they occupy fully one-third of the mapped area. The bench gravels, wdiich are of glaciofluvial origin, are most con- spicuous about the mouth of Dan Creek, the lower parts of Chititu and Young creeks, and on McCarthy Creek, but are present in other places also. DRAINAGE. Nearly all the larger streams of the Nizina district originating within the mountain area head in glaciers, and those that do not thus head nevertheless receive much of their water from melting snow banks throughout all or part of the year. All the streams are swift and subject to rapid variations in quantity of water flowing in them. Nizina Kiver falls 600 feet in 19 miles within the mapped area, or at the rate of 31.5 feet per mile. McCarthy Creek has a grade of 100 feet per mile and Chititu Creek 180 feet per mile in their lower courses. In contrast with the well-drained mountain areas, the lowlands are swampy and dotted with numerous ponds and lakes. They are cov- ered with an inferior growth of spruce and with moss that acts like a sponge to hold water and prevent its rapid run-off. The surplus water from the lakes is carried away in sluggish clear-water streams. These features are characteristic of the southwest part of the mapped area. Trails in such country are often almost impassable for horses in summer, and for that reason they keep to the gravel bars or the ridges. DESCRIPTIVE GEOLOGY. STRATIGRAPHY. SEDIMENTARY ROCKS. ROCK TYPES. It has already been stated that the Nikolai greenstone is the oldest rock formation exposed in the Nizina district and that it is conform- ably overlain by the Chitistone limestone and a shale formation (McCarthy shale), both of which are of Triassic age. It was further stated that a great thickness of shale of Jurassic age — the Ivennicott formation — rests unconformably upon the upturned edges of the greenstone, limestone, and shale; that these formations, particularly the Ivennicott, were intruded by light-colored porphyritic igneous rocks ; and that the most recent deposits of the district are unconsoli- dated gravels of Quaternary age. SEDIMENTARY ROCKS. 21 The Nikolai greenstone, because of its relation to the Chitistone limestone, its importance as a geologic formation, and its structure, might fittingly be described in connection with the sedimentary formations. Inasmuch, however, as it is of igneous origin, its descrip- tion will be taken up later in its proper place in the account of the igneous rocks. TRIASSIC SYSTEM. CHITISTONE LIMESTONE. CHARACTER OF THE FORMATION. The name Chitistone was applied by Rohn to the great Triassic limestone of the Nizina district because he found the limestone best developed along the Nizina in the vicinity of the mouth of Chiti- stone River. This name was later adopted by Schrader and Spencer and has since come into general use. The Chitistone limestone is a conspicuous formation occurring all along the south flanks of the Wrangell Mountains from Kotsina River to Dan Creek and prob- ably extending into the valley of the upper Chitina. In the Nizina district the lower part of the Chitistone formation is made up of thick, massive beds of a dark-gray or bluish-gray color but weather- ing to a lighter gray on the surface. The upper part, on the other hand, is made up of thinner beds, and this thinness increases toward the top. A slight difference in chemical composition between the upper and the lower parts of the Chitistone limestone is indicated by the brownish-yellow weathering of the upper part. Changing conditions of sedimentation are indicated, too, in a more noticeable way by the appearance of thin shale beds at the top of the formation. This limestone is the oldest of the sedimentary formations exposed within the mapped area and lies on the Nikolai greenstone conform- ably, exactly as if both were sedimentary formations deposited in the same sea and the limestone had been laid down on the greenstone before any movement or disturbance had taken place in the green- stone. This conformable relation holds true wherever the contact has been examined, although in many places it is found that there has been movement of the two formations along this contact surface. In several places a bed of red and green shale with a maximum thick- ness of about 5 feet was found to intervene between the limestone and the greenstone, but it is not known whether the shale is widely distributed or not, since the limestone-greenstone contact is nearly everywhere covered with talus. The shale is present in the vicinity of Bonanza mine and on Kennicott Glacier. Excellent sections of the Chitistone limestone are seen on the west side of Nizina River, opposite the mouth of Chitistone River, and on McCarthy Creek. On McCarthy Creek the lower part of the forma- 22 THE NIZINA DISTRICT, ALASKA. tion, which dips about 30° NE., consists of massive beds of bluish- gray limestone, making up approximately three-fifths of the total thickness. Above this lower massive portion is a succession of more thinly bedded limestone strata weathering a rusty-yellow color and making up the remaining two-fifths of the formation. The thick- ness of individual beds decreases from the base toward the top, as has been stated, and near the top thin beds of black shale make their appearance. Then comes an indefinite thickness, approximately 300 feet, of thin-bedded limestone and shale overlain in turi^ by a great thickness of black shale, which Rohn called the McCarthy Creek shale.® It is thus seen that there is a transition from the bedded limestones below through interbedded thin limestones and shales to shale above, and it is readily understood that difficulty arises in choosing a definite dividing plane between these two formations. The section on Nizina River shows the same features as that on McCarthy Creek, but here the whole syncline is exposed, revealing the steep northward dip on the south, the horizontal bedding in the middle, and the gentle southward dip on the north. The bedding features are well shown in the center of the syncline for the whole succession from base to overlying shales. (See Pl. V.) DISTRIBUTION. The Chitistone limestone occupies a narrow band along the north- eastern edge of the mapped area, extending southeastward from Kennicott Glacier (at the northern limit of the area) to the head of Copper Creek. The dip of the limestone along its southern bound- ary is to the northeast and decreases from approximately 30° in the vicinity of Kennicott Glacier and McCarthy Creek to only a few degrees on Dan and Copper creeks. It results from this that the width of the limestone belt is much less at the glacier and on Mc- Carthy Creek than on Dan Creek. The limestone belt has a width of slightly more than 1 mile on the ridge between McCarthy Creek and East Fork, which is probably less than its width at any place between McCarthy Creek and Kennicott Glacier. East of Nizina River the limestone caps the mountains between Dan Creek and Chitistone River in the form of a broad, shallow syncline fully 5 miles wide. The continuity of limestone exposures is interrupted in many places by valley gravel and talus deposits, but aside from separate limestone areas produced in this way there are a number of small detached areas wffiose separation from the principal lime- stone masses represented on the map is due to other causes. Such an area is seen at the head of Nikolai Creek and ow T es its isolation to the fact that the overlying Kennicott formation has been only partly eroded. If all of the conglomerate and sandstone of the Kennicott " Rohn, Oscar, A reconnaissance of the Chitina River and the Skolai Mountains, Alaska : Twenty-first Ann. Kept. U. S. Geol. Survey, pt. 2, 1900, p. 426. LIMESTONE WALL ON WEST SIDE OF NIZINA RIVER NEAR MOUTH OF CHITISTONE RIVER. SEDIMENTARY ROCKS. 23 were removed, the small limestone area would be found to be part of the larger area to the east. Another isolated area lies south of Dan Creek, but in this case the limestone was separated from the main limestone mass to the north and reached its present position through faulting. THICKNESS. The two localities on Nizina River and McCarthy Creek afford favorable opportunities for measuring the thickness of the Chitistone limestone, since in both places the whole formation is present. One element of uncertainty presents itself, however — the difficulty of choosing the somewhat arbitrary plane to separate the limestone from the overlying shales; yet, since the intervening thin-bedded shale- limestone succession is probably less than 300 feet thick, the error in measurement, and the results are the same as on Nizina River. A 5 per cent, as will be seen later. The base of the limestone in the central part of the syncline on Nizina River is hidden by river gravels, but since the curve of the beds is small and regular and greenstone is exposed along the base of the cliffs only a short distance north and south of the axis of the syncline, it is evident that almost the complete section of the lime- stone is shown in one vertical column. This section gives a thickness of 3,000 feet for the Chitistone limestone in its type locality. The McCarthy Creek section gives an almost equally good chance for measurement, and the results are the same as on Nizina River. A section north of Chitistone River gives a greater thickness than 3,000 feet, but as in this locality the limestone has been folded and faulted it is believed that the figures there are less reliable than those first given. Exposures of Chitistone limestone extend westward to Kotsina River, less than 15 miles from Copper River, but the thickness is much less than in the Nizina district and in places is not more than 200 or 300 feet. No evidence has been collected to show that the limestone becomes progressively thinner from the east toward the west in Chitina Valley, and, although that may be the case, the de- creased thickness in the valleys of Kotsina River and Elliott Creek may be due to erosion before deposition of the Kennicott formation took place. AGE. The age of the Chitistone limestone was long in doubt but is now known to be Upper Triassic. This age determination is based on fossil collections made in 1907 at a number of localities along the limestone area from Kotsina River to the Chitistone and on larger collections made in the Nizina ‘district in 1909. All the collections were submitted to T. W. Stanton for determination and the forms present are contained in the following lists. These lists include, 24 THE NTZTNA DISTRICT, ALASKA. however, only the species collected within the area of the Nizina special map. The numbers given the specimens are the catalogue numbers in the National Museum. Concerning the collection of 1907 Dr. Stanton says in part : The collection is small and fragmentary, blit it has proved sufficient to show quite conclusively that the beds in question are of Triassic age. The am- monites, especially, are all characteristic Triassic types, and the few brachiopods obtained are also Mesozoic. There is no indication of Paleozoic fossils in any part of the section represented. * * * The following lists give the form recognized from each locality. In most cases specific identifications have not been possible, but this does not lessen the accuracy of the age determination : Bonanza mine and Bonanza Creek : 4808; Nos. 9, 14 to 19, 21, 22— Undetermined corals. Terebratula sp. Spiriferina sp. Hinnites? sp. Pseudomonotis subcircularis (Gabb)? Jumbo Creek, near the Bonanza mine: 4809; Nos. 10 to 13, 20— Pentacrinus sp. Terebratula sp. Avicula? sp. Arcestes? sp. The last two named are certainly Triassic types of ammonites and probably belong to the genera to which they are provisionally assigned. South side of Chitistone River : 4810 : Nos. 23, 24— Spiriferina ? sp. Halobia sp. Arcestes? sp. Tropites? sp. The last two are Triassic ammonites provisionally identified from imperfect specimens. The list of fossils collected in 1909 is here arranged by localities. Dr. Stanton says of them : The fossils from the Chitistone confirm the recent determinations of that hori- zon and definitely prove that it is of Triassic age. Jumbo Creek : 6300- Base of Chitistone limestone corals? Too obscure for identification. McCarthy Creek : 6330— Terebratula sp. Probably Triassic. Nikolai Creek : 6303— Halobia sp. ; related to H. superba Mojsisovics. Undetermined Pelecypod. 6306— Juvavites? sp. Arcestes sp. SEDIMENTARY ROCKS. 25 Nikolai Creek — Continued. 6312— Pseudomonotis subcircularis (Gabb). Arcestes sp. Juvavites? 2 sp. Orthoceras sp. Cbitistone River : 6319— Tropites sp. (Lower part of Cbitistone limestone.) 6320— Halobia superba. Arcestes. 6333— Halobia superba Mojsisovics? Arcestes sp. Copper Creek : 6321— Halobia superba Mojsisovics? When Schrader and Spencer studied the geology of the Chitina Valley in 1900 they found no fossils in the Chitistone limestone and were unable to give conclusive evidence concerning the age of the limestone. They, however, correlated it with the massive Carbonif- erous limestone at the head of White River, first described by Hayes® and later by Brooks. * * 6 This limestone is exposed on the north side of Skolai Creek, one of the eastern tributaries of Nizina River, and is conspicuous in Skolai Pass, between the heads of Skolai Creek and White River. The correlation of limestones so similar in appearance and so near to each other seemed to have much in its favor, but better oppor- tunities for study have proved it to be incorrect. Although the Chitistone limestone can not be correlated with the limestone on White River, it is known that limestone similar in appearance and of the same age as the Chitistone limestone is present on the north side of the Wrangell Mountains, in the depression be- tween them and the Nutzotin Mountains. There is, however, no such development of Triassic limestone there as is seen in the Chitina Valley, and the known exposures are confined to one small area. A table of correlations for the Mesozoic sedimentary rocks of Alaska is here given, from which it appears that Triassic rocks, so far as they are known at present, are confined to the region south of the Alaska Range. Aside from the Chitina region, Triassic rocks probably have their greatest development in the Cook Inlet region, w T here they occur principally in the form of cherts with a small proportion of shale and limestone beds. ° Hayes, C. Willard, An expedition through the Yukon district : Nat. Geog. Mag., vol. 4, 1892, p. 140. 6 Brooks, Alfred H., A reconnaissance from Pyramid Harbor to Eagle City, Alaska: Twenty-first Ann. Kept. U. S. Geol. Survey, pt. 2, 1900, p. 359. Correlation of the Mesozoic sedimentary rocks of Alaska. 26 THE NIZINA DISTRICT, ALASKA. C3 ~ qj O 'a £ ss G G o c3 ~ "S Qj G ora w . «s c3 3 w -W 5 ^Jggja g * I 3*3’S62fg ^ “ H ’5b g -2g ■* 5,2 I c £ 2 JS 2 >°£°2 J M g sScoiio§§§ ^ o 8 S 5-2 £ o c ra c m 0 -m ^ G c! ^ m to cj„ M.h ◄ w aT 1 ^ -5 § SCxhII »?oo St-.-M. G <9°§ •5§ C3 .2 C.U Seng'S •ti 03 _» £ S c3 -C3 c3 "SSS-g §i|a ■s fcsLS § g •geg^U d U. O > co co ffl *M C o -52 O co . « .IB® G G -M G § ,o ra o O K •snoeoBjajj OlSSBjn£ SEDIMENTARY ROCKS, 27 a 3 * B4 g'3'O Eoci c3 09^ « 3 S ~ p © 3 ■Sill <1 §2s|a ■ts ® "S »r m s S.^IJI U C/3 CO £ “1 M CO r O J, -3 >V3 >> © ®gc=2«> S V) 0) aS 35 s 03 CD >>0 •G'g . ■£ *2 0) 3s| uO w d.6 -Zd o o „ ©02 O S PI 6 S ^»d © o >02 w « CO , _ w . w _ w © s CO P^gg - . pio .^Sea« d ffi % O 0 -’ - ' o „J d £dSS S o •<8 ^ g £ >» W 'O 53 _;• oa S b ■o^Se^ g'gJoQ^.Sg >> S<$>-' . •3 :t3o ^ £H £• SrjS: .isP ■3 ^ <, fn < ~ eSds-Sfo ©‘3 g3 os 3 hr ~-q P-aifQ!>ffiaa “OISSBIJJj 28 THE NTZTNA DISTRICT, ALASKA. McCarthy shale. CHARACTER OF THE FORMATION. The term McCarthy Creek shale was used by Rohn to designate the black shales immediately overlying the Chitistone limestone, and the formation was described by him as “ a series of soft, black, highly fissile shales and slates.”® The formation as it is exposed in the Nizina district is essentially a shale formation, although at its base are numerous thin limestone beds forming part of the transition zone at the top of the Chitistone limestone or the base of the shale. Thin beds of limestone are found interstratified with the shales wherever they are exposed within the mapped area, but are not abundant and form only a small proportion of the whole. The top of the McCarthy shale has not been recog- nized. Bedding is easily distinguished in most places either by the presence of the thin limestones or of thin limy shale beds with surfaces highly colored by weathering. Some of the smooth bare hilltops about the eastern tributaries of East Fork are marked with exceedingly intricate patterns produced by the colored beds, for the McCarthy shale is found to be intensely folded wherever it has been examined, and if the folds are cut by planes or curved surfaces making slight angles with their axes the patterns appear. The folding in the McCarthy shale strongly contrasts with both that of the Chitistone limestone and that of the Ivennicott formation. Pronounced folding took place in the upper thin-bedded part of the limestone in a few localities. It begins to be conspicuous in the transition beds at the base of the shale (see PI. IV, B , p. 18) but was never found in the massive beds at the base of the limestone. The limestone beds were more able than the shale to withstand the pressure that tended to deform them, and that ability increased as the thickness of the beds increased. Another factor of strength lay in the massive flows of the Nikolai greenstone, which lent its support to the heavy beds of the limestone in resisting deformation. DISTRIBUTION. The principal area of McCarthy shale represented on the geologic map (PI. Ill, in pocket) lies between McCarthy Creek and Nizina River, at the north edge of the sheet. This, according to Rohn, is the south edge of a succession of shales extending north in the McCarthy Creek valley for a distance of G or 8 miles and consti- tuting the type locality for the formation. This is not only the largest area of the shales examined but it also shows a greater thick- ness than any other area, for it suffered less from erosion before the Ivennicott formation was deposited. a Rohn, Oscar, A reconnaissance of the Chitina River and the Skolai Mountains, Alaska : Twenty-first Ann. Rept. U. S. Geol. Survey, pt. 2, 1900, p. 426. SEDIMENTARY ROCKS. 29 The McCarthy shale and the shale-limestone transition zone below it form the base of the mountains south of Copper Creek. The for- mation is separated from the overlying Kennicott formation by a distinct unconformity, but the black shales of the two formations are so similar in appearance that they were not distinguished until the detailed work of 1909 was undertaken. Only the base of the McCarthy shale is exposed on Copper Creek. The upper part was removed by erosion before deposition of the Kennicott began. A smaller area of the Triassic shale forms the mountain top north of Texas Creek, and the formation is present in other places overlying the limestone north of Dan Creek but does not fall within the boundaries of the mapped area. THICKNESS. Accurate measurements of the thickness of the McCarthy shale were not obtained, because it is probable that only a part of the total thickness is exposed within the mapped area. It is possible, more- over, that the complete original section is* no longer represented in this district, for a long erosion interval intervened between the depo- sition of the Triassic shales and the Jurassic shales. During this interval much of the Triassic sedimentary formations and of the Nikolai greenstone was removed. Another factor of uncertainty besides the amount of the shales that have been removed by erosion is the thickening and reduplication of beds that arise from folding and faulting. It is probable, however, that the McCarthy shale has a thickness nearly as great as the Chitistone limestone ; possibly it is greater. A thickness of about 1,500 feet of Triassic shale overlies the lime- stone on the west side of Nizina River. The shales near the center of the broad syncline in this locality have a horizontal position and are probably less distorted by folding than they are to the north- west. This measurement is considered the minimum and probably much less than the true thickness, for some of the shale has certainly been removed by erosion. The mountains about the head of the East Fork of McCarthy Creek are made up of the black Triassic shales. They reach an altitude of 6,960 feet above sea level or 3,000 feet above the limestone shale boundary at the creek on the southwest. The shales are much folded about the upper part of the East Fork valley, and measurements are consequently uncertain, but it is probable that the thickness of the formation is at least 2,500 feet in this vicinity. ^No measurements of value were obtained in the Copper Creek section, for, as previously stated, only a part of the formation is present there. It is evident from what has been said that the total thickness of Triassic sediments in the Nizina district is great and that it is prob- 30 THE NIZINA DISTRICT, ALASKA. ably not less than 6,000 feet. One-half of this figure represents a limestone whose thickness can be stated with a considerable degree of accuracy; the remainder represents a great shale formation whose thickness is stated only approximately. AGE. The McCarthy shale is of Upper Triassic age. Some of the beds are abundantly fossiliferous, especially those near the base of the formation and in the transition zone below, and fossils can usually be found in the higher parts of the formation if search is made for them. Shells of Pseudomonotis subcircularis (Gabb) are so plentiful in some of the shale beds between the thin limestones that the rock can not be broken without showing them; they appear, however, to be almost the only forms represented. A list of fossil localities follows; the determinations are by T. W. Stanton. McCarthy Creek : * 6314 — Pseudomonotis subcircularis (Gabb). Nikolai Creek: 6311 - Two or more undetermined ammonite genera represented by frag- mentary specimens. Dan Creek : 6317 — Pseudomonotis subcircularis (Gabb). Copper Creek (two localities) : 6323 — Pseudomonotis subcircularis (Gabb). 6335 — Pseudomonotis subcircularis (Gabb). Areas of Triassic shale are scattered along the south slope of the Wrangell Mountains as far west as the Kuskulana and probably as far as the Kotsina also, but in the earlier work in this region the Triassic shales and the black Jurassic shales were not separated because the presence of an immense thickness of Jurassic shales in this valley was not known at that time. It is now certain that a considerable part of the shale areas of Chitina Valley formerly con- sidered to be Triassic are in reality of Jurassic age. No Triassic shale corresponding in thickness or other characters to the McCarthy shale is known in Alaska. Other regions of Triassic sediments of similar age have been pointed out (see correlation table, pp. 26-27), but the conditions under which they were deposited were different from those in the Nizina district, and although they may be in part contemporaneous the resulting formations are distinct. SEDIMENTARY ROCKS. 31 JURASSIC SYSTEM. KENNICOTT FORMATION. CHARACTER OF THE FORMATION. The name Kennicott was adopted by Rohn to designate the con- glomerate and sandstone succession which he found resting uncon- formably on the Triassic shales of McCarthy Creek and correlated on fossil evidence with the light-colored arkoses, shales, and lime- stones between Lachina River and Kennicott Glacier. Rohn did not recognize the black shale south of Nikolai Creek as part of his Kenni- cott formation, but within the district under consideration the black shale is far more important in amount than the basal con- glomerate and sandstone members. The Kennicott formation as the term is here used consists largely of black shale, but it includes conglomerate, grit, sandstone, and impure limestone members and is intruded by great masses of light-colored porphyritic rock. It is the youngest of the consolidated « sedimentary deposits represented on the geo- § logic map (PI. Ill, in pocket) and is more widely distributed within the mapped area than any of the formations previously de- scribed. One of the characteristics of the Kennicott is its variation in appearance and composition at different localities. This statement is more applicable to its basal than to its upper part and refers to features £ that resulted from changing shore conditions | of sedimentation. These differences will be w brought out by a description of the Jurassic rocks northwest of Nizina River, where the basal part is better represented, and south- Fl east of Nizina River, where the middle and upper parts are better represented. The Kennicott formation where it is exposed about the head of Nikolai Creek may be subdivided into three members as follows: A basal member made up of conglomerate and sandstone ; a second member consisting chiefly of light-gray, yellow-weathering shale; and an upper member of dark-gray or black shale interstratified with occasional beds of impure limestone or hard calcareous shale (fig. 2). The basal member shows notable differences in lithologic character and thickness as it is followed from one outcrop to another. Black shale with hard calcareous beds ; fos- sils. Gray, yellow-weather- ing shales; fossils. Y ellow-w eathering sandy shales. Yellow-w eathering sandstones; fossils. Conglomerate (locally with large blocks and bowlders) grad- ing upward into fine grit. Some beds with an abundance of broken shells. Unconformity. Limestone and green- stone. gure 2. — Columnar section of the basal part of the Kennicott formation ex- posed on Nikolai Creek. 32 THE NIZINA DISTRICT, ALASKA. These differences, except in thickness, are dependent in large measure on the kind of rock immediately underlying the Kennicott. In nearly all places the lowest beds of the formation consist of con- glomerate, but this conglomerate presents a different appearance in almost every exposure, for there is nearly every gradation between an even-grained grit who§e well-worn pebbles are of uniform size and no larger than grains of wheat to a coarse agglomerate with blocks and bowlders up to 8 or 10 feet in diameter (PI. YI, A). Such coarse material has probably traveled but a short distance from its source and may represent a shore-line cliff. It is not a constant feature of the basal Kennicott and its exposures are not extensive, for the very large bowlders are found in only a few localities. In many places it was noticed that most of the pebbles in the conglomerate are of the same material as the. older beds on which the conglomerate rests — that is, where conglomerate overlies greenstone most of the pebbles are greenstone and where it rests on the Triassic shale most of the pebbles are shale. Limestone pebbles are not so numerous as pebbles of greenstone and shale, yet con- glomerate of this formation containing a large proportion of rounded limestone fragments is found in other parts of the Chitina Valley. Some of the conglomerate contains a considerable number of diorite and porphyry pebbles, but it was not found in place in the vicinity of Nikolai Creek, where the basal conglomerate of the Kennicott is best developed wdthin. the area mapped. Nearly all of the frag- ments are well rounded and waterworn, and it is only in the very coarse conglomerate that angular outlines are noticeable. Even in such places the edges and corners of the blocks are usually worn away. The filling between pebbles is finely ground material from the same source as the pebbles and is for the most part a greenish sandstone or graywacke. The average size of fragments composing the basal mem- ber of the formation decreases rapidly as distance from the base in- creases, until the conglomerate gives way to sandstone. In most local- ities about Nikolai Creek where exposures occur it is found that the up- per half or three- fourths of the basal member consists of fine greenish sandstone or graywacke containing little quartz and seemingly derived largely from the Triassic shale and the greenstone. This upper part shows far less variation in character than the conglomerate, although in the base thin beds of graywacke alternate with thin beds of con- glomerate. There are places where the fine conglomerate and gra} T - wacke contain considerable lime and become practically an impure limestone, but such beds are not persistent. Some of them consist in part of broken shells, yet it is difficult to find determinable fossils among them and still more difficult to secure the fossils when found, since they are in most cases partly decomposed and fragile. U. S. GEOLOGICAL SURVEY BULLETIN 448 PLATE VI A. BOWLDERS IN CONGLOMERATE AT BASE OF KENNICOTT FORMATION ON SOUTH BRANCH OF NIKOLAI CREEK. See page 32. B. SANDSTONE OF KENNICOTT FORMATION ON RIDGE SOUTH OF NIKOLAI MINE. See page 33. SEDIMENTARY ROCKS. 33 This lowest conglomerate-sandstone member of the Kennicott for- mation on Nikolai Creek has a thickness ranging from 25 to 125 feet, the greater part of which is graywacke, the remainder con- glomerate or grit. In a few places the basal member appears to be entirely absent, although because of faulting and talus slopes its seeming absence may be explained in other ways. Furthermore, its persistence as a whole in many other places in spite of rapid changes in character and of variation in thickness makes it probable that if it is not seen in a particular locality the failure to find it is due to one of the causes mentioned. The middle member of the formation on Nikolai Creek shows far less variation in character than the lower one, but it does not ap- pear so conspicuously in other parts of the Nizina region. It con- sists of shale and shaly sandstone, but shale predominates. The sandy phases are more or less local, and the best exposures are on the ridge south of Nikolai mine (PL VI, B). A freshly broken surface of the shale show T s a fine-grained rock of light color, but both shale and sandstone weather a bright yellow that makes them conspicuous wherever they are exposed. Both shale and sandstone break down into thin fragments under the influence of the weather, and the debris from their ledges give rise to prominent talus slopes. Occasionally fossils are found in the sandstone, and rarely a shell is seen in the shale, but fossils are not abundant and it requires some search to find any of value. The thickness of the yellow- weathering shales is as great as 500 feet in the mountain between Nikolai Creek and the East Fork of McCarthy Creek. At the head of Nikolai Creek 375 feet of yellow- weathering shale overlies the conglomerate, but some of the shale has been eroded away. The highest member of the Kennicott in the Nikolai Creek vicinity consists of black shale, with interstratified hard, impure limestone and calcareous shale beds ranging in thickness from 1 inch to 2 feet. The hard beds form only a small proportion of the total thickness, probably less than one-tenth, but although jointed and broken they stand out in relief from the softer, crumbling black shales and form a conspicuous part of the whole. This black shale resembles closely the black shales of the Triassic. The hard beds assume a rusty- yellowish color on weathering, just as in the Triassic shales, and there seems to be no way, except by their stratigraphic position and their fossils, to distinguish them from the older shales. Fossils are fairly plentiful in some beds of this member, especially those in the hard beds, and are in a better state of preservation than those found lower in the formation. From 125 to 150 feet of these shales are exposed north of Nikolai Creek, but the figures take no account of what has been removed by erosion or what has been caught up into the intruded porphyry. 70648°— Bull. 448—11 -3 34 THE NIZINA DISTRICT, ALASKA. Locally erosion has destroyed the upper member, leaving the basal and middle members. In some localities both the middle and the upper members have been removed, and without doubt the Kenni- cott was once present in large areas where no trace of it is now found. The section of the Kennicott formation exposed on Dan Creek is many times thicker than the section that has been described. The Nikolai section represents a phase of the basal Kennicott that is thought to correspond more fully with the Kennicott observed west of Kennicott Glacier and still farther west in the Chitina Valley than does the Dan Creek section. An excellent exposure of the base of the Kennicott formation was found on Eagle Creek, in the Copper Creek valley. All the upper part of the long ridge separating Eagle Creek from Copper Creek is made up of lower Kennicott beds. They rest on the edges of thin limestone and shale beds that belong to the transition zone between Chitistone limestone and McCarthy shale. The limestone and shale beds have a dip about 20° greater than the overlying Kennicott, and the unconformity is shown in diagrammatic clearness. The basal beds of the Kennicott at this place consist of from 150 to 200 feet of fine conglomerate or grit overlain by sandstone. Black shale overlies the sandstone and forms the top of the ridge extending southeast to the main mountain mass. This basal grit was traced northwest in Copper Creek valley to the vicinity of the limestone area north of Idaho Gulch. It may be regarded as a constant feature of the Kennicott in the Nizina district. In most places it is somewhat fossiliferous. Pyramid Peak, at the head of Copper Creek, appears to be made up entirely of rocks belonging to the Kennicott formation. The lower part is black shale, but the top shows bedding lines that are thought to rep- resent sandstones and impure limestones. Sandy shales and hard sandstones are interstratified wfith the black shales on Rex Creek, and the tops of the mountains between Rex Creek and White Creek contain a large amount of gray sandstone and impure limestone. Beds of brown-weathering nodular limestone in the shales high up on the slopes of these mountains contain ammonite shells 15 or 18 inches across. These mountains appear to be at the axis of a broad shallow syncline and give good sections of the formation. A feature of geologic interest is presented by the sandstone dikes that cut the black shales east of Rex Creek. These dikes range in thickness from a fraction of an inch to 5 or 6 inches and cut the shales just as an igneous dike would. They are composed of angular frag- ments of quartz, feldspar, biotite, calcite, and pyrite mingled with fragments of shale. They are composed of the same material as some of the associated sandstone beds and are numerous in places. Bedding in the black shales of Blei Gulch, on the south side of Chititu Creek, is shown by lines of small limestone concretions and SEDIMENTARY ROCKS. 35 thin discontinuous calcareous beds. More than 4,500 feet of black shale dipping low to the southwest is exposed in Blei Gulch. Young Creek, south of Chititu Creek, flows in a shallow canyon whose walls are composed of black shale of the Kennicott formation. This shale forms the lower slopes of the ridge south of Young Creek, and it is probable that Kennicott sediments make up most of the ridge. The ridge was not examined in detail owing to lack of time, but a section up the first southern tributary of Young Creek east of Calamity Gulch shows rocks of the Kennicott formation. The section extends up the, east branch of this creek. For a distance of nearly three-fourths of a mile from its mouth the creek flows over black shales with occa- sional limestone beds, all dipping southwest at angles of 30° or less. Thence for nearly a fourth of a mile are rocks that have been crumpled and much faulted. They consist of shales with interbedded cal- careous shales and limestone, from which fossils were collected. In many places the strata of this disturbed zone stand on edge, and it is evident that displacements of importance have taken place. A peculiar feature of this locality is seen in the limestone nodules, which occur in beds and reach diameters of 2 or 3 feet. They consist of bluish-gray limestone and show parallel bedding lines crossing them. They were seen at a number of places on Young Creek. South of this faulted zone the creek flows for another three- fourths of a mile over black shales and thin gray and brown sandstones. The shale pre- dominates but the sandstones form an important part of the whole. The dip of these shales and sandstones is steeper than is usual in the Kennicott formation of the Nizina district, ranging from 30° to 50°. A massive conglomerate succeeds the shale and limestone on the south at a point 1,500 feet above Young Creek. The conglomerate is several hundred feet thick and is made up of well-rounded pebbles loosely cemented together, many of which are 5 or 6 inches in diam- eter. It appears to have been deposited conformably on the under- lying shale-sandstone beds, but there is reason to believe that move- ment has taken place along the contact at this locality. No proof was secured to show that this great conglomerate does not mark an unconformity in the Kennicott formation or between the Kennicott and a succeeding formation, but the- relation appears to be one of conformity in other places west of this creek where the contact was examined. Flat-topped or mesa-like hills composed of conglomerate beds dipping low to the south are scattered along the top of this ridge both to the east and to the west of this section. According to Schrader’s field notes of 1900, the conglomerate on the west end of the ridge south of Young Creek is interstratified with a few beds of arkose sandstone and probably does not exceed 500 feet in thickness. It contains granite bowlders up to 9 inches in diameter, dark lime- stone, flint, quartz, gray slate and grit, and green gneissic rock, but 36 THE NIZINA DISTRICT, ALASKA. Schrader did not find any pebbles of Nikolai greenstone. The arkose or sandstone underlying the conglomerate was measured by Schrader in a very favorable section, where the dip was low to the south-south- east, and was found to be between 2,000 and 2,500 feet in thickness. There is no reason to doubt that this succession of shales, lime- stones, sandstones, and conglomerate found in the ridge south of Young Creek corresponds to the bedded rocks seen in the high moun- tains at the head of Copper, Rex, and White creeks. It therefore represents the upper part of the Kennicott formation as it is known at present. The unconformable relation of the Kennicott formation to the older sedimentary rocks and the Nikolai greenstone is plainly seen in both the localities whose sections have been described and is shown in the view (Pl. VII, A and B) taken at the head of Nikolai Creek. Kennicott sediments there rest on the upturned and truncated beds of the Nikolai greenstone, the Chitistone limestone, and the Mc- Carthy shale. The dip of the younger beds is low in most places, ranging from 10° to 20° W. or SW. On the other hand, the dip of the underlying sediments and the lava flows (Nikolai greenstone) are considerably greater and in a different direction, averaging about 30° or 35° NE. One feature of the Jurassic sediments that is more noticeable on White and Young creeks than in other parts of the district is the rapidity with which they break down under the action of weathering. Such topographic forms as Blei Gulch and the gulches tributary to Young Creek are due to this cause. Blei Gulch in particular shows how readily the shales are attacked and how little they are able to resist the attacks as compared with the greenstone and lime- stone. The soft shale debris accumulates faster than the water can carry it away and the mouth of the gulch is choked with it. The Kennicott was deposited on an old submerged land surface. In a broad way this surface on which the Kennicott formation of Nikolai Creek lies was flat, but it is readily seen on examining the contact that there w r ere minor irregularities in it such as are present in any level country. The conglomerate and graywacke beds of the basal Kennicott sag down into hollows of the underlying surface, and at one locality pebbles and sand were seen filling old cracks in the Chitistone limestone. DISTRIBUTION. The Kennicott formation occupies probably three-fourths of the total area represented on the geologic map (PI. Ill, in pocket), for if a line be drawn from the mouth of National Creek to Pyramid Peak practically all of the consolidated deposits south of it are Kennicott. It forms the high angular mountains between Dan and Chititu U. S. GEOLOGICAL SURVEY BULLETIN 448 PLATE VII B. UNCONFORMITY BETWEEN TRIASSIC AND JURASSIC FORMATIONS AT HEAD OF NIKOLAI CREEK. a, Sandstone and shale of Kennicott formation; b, Chitistone limestone; c, Nikolai greenstone. The two views placed side by side would form a panorama. See page 36. SEDIMENTARY ROCKS. 37 Conglomerate with interbedded sand stone. creeks and makes up the principal part of Porphyry and Sourdough peaks, although its presence is so obscured by porphyry intrusions in these two last-mentioned mountains that its amount is apt to be underestimated. It doubtless underlies also the gravel deposits of the lowland south of Nizina River. Without question Jurassic sediments are far more widespread in Chititu Valley than was suspected before the field work of 1909 was undertaken. They extend eastward beyond the Nizina district into the upper valley of the Chitina and westward along the flanks of the Wrangell Mountains, where it is certain that they have not been fully differentiated from the Triassic shales, just as was true in the Nizina district. The separation of Juras- sic from Triassic shales will require more de Black shale with a few limestone — ^ beds. tailed field work than has yet been given them. THICKNESS. No such favorable section was found for measuring the thickness of the Kennicott for- mation as that furnished by the walls of Nizina River for measuring the Chitistone limestone, and the figures given are secured from a study of a number of sections at differ- ent localities (fig. 3). The total thickness given should be regarded as having only approximate accuracy. The coarse fragmental beds, including con- glomerate and grit at the base of the Kenni- cott, range in thickness from 25 to 150 or 200 feet. An intermediate figure of 100 to 150 feet is believed to represent a fair estimate for the thickness of these beds throughout the dis- trict. It seems proper to include the yellow- weathering shales and sandstones of Nikolai Creek with the black shales, since they are a local feature and contemporaneous in time of deposition with the lower part of the black shale south of Nizina River. On this basis the black shale mem- ber at the heads of Copper and Rex creeks has a minimum thick- ness of not less than 4,500 feet, yet the black shales of Williams Peak south of Dan Creek suggest a considerably greater thick- ness, possibly as much as 6,000 feet. This measurement includes all beds from the top of the conglomerate and grit to the begin- Interbedded sand- stone and shale. Yellow -weathering shale and sand- stone; changes to black shale in places. Conglomerate. Triassic shale-lime- stone beds. Figure 3. — Generalized columnar section of the Jurassic sediments in the Nizina district. 38 THE NIZINA DISTRICT, ALASKA. ning of the interbedded shale-sandstone succession that forms the tops of the high mountains at the heads of Copper and Rex creeks and the upper part of the ridge south of Dan Creek. The shale- sandstone member has a thickness of about 2,500 feet. If, now, 500 fee*, representing the heavy conglomerate of Young Creek, be added to the measurements already given, a minimum thickness of over 7,500 feet is obtained for the Kennicott formation in the Nizina district. AGE AND CORRELATION. Fossils have been collected from all parts of the Kennicott forma- tion, but unfortunately the stratigraphic range of the forms is so great that they do not fix its age definitely. It appears most prob- able that the Kennicott formation was laid down in Upper Jurassic time, but there is a possibility of its being Lower Cretaceous. The probability of its Jurassic age rests in considerable measure on the presence of a species of Aucella collected first by Rohn and later by Schrader and Spencer and identified by T. W. Stanton. Schrader and Spencer collected fossils at other localities as well as in the Nizina district, and on the evidence of these fossils the formation was referred to u the doubtful series lying at the top of the Jurassic or at the base of the Cretaceous.”" The list of fossils follows. Inoceramus eximius Eicliwald? Belemnites sp. Halobia occidentals AVliiteaves? Rhynchonella sp. Pecten sp. Avion la sp. Aucella pallasi Keyserling? Lytoceras sp. Hoplites sp. Olcostephanus? sp. Gryphaea sp. Sagenopteris sp. Concerning Inoceramus eximius Dr. Stanton says : ° This form is represented by a single specimen collected on Chitty Creek. It may be distinct from Eichwald’s species originally described from Turkusitun Bay, in Cook Inlet, and referred by him to the Neocomian. Eichwald described three other species — /. ambiguus , I. porrectus, and I. lucifer — all belonging to one section of Inoceramus from the same horizon in Alaska. The present shell does not agree perfectly with any of the figures, but it is most nearly like I. eximius and probably comes from the same formation. Similar forms occur both in the Jurassic and in the Cretaceous, but the evidence of the other fossils from this part of Alaska favors the reference of the Kennicott forma- tion to the Jurassic. ° Schrader, F. C., and Spencer, A. C., The geology and mineral resources of a portion of the Copper River district, Alaska: Special publication of the U. S. Geol. Survey, 1901, p. 50. SEDIMENTARY ROCKS. 39 Of the form referred with a question to Halobia Occident alls Dr. Stanton says: The specimens agree fairly well in sculpture and general appearance with some of the figures of Whiteaves’s species from the Liard River and may be identical with it. They are, however, somewhat suggestive of Hinnites linwnsis, from the Jurassic(?) of Siberia. Sagenopteris is a genus which occurs both in the Jurassic and in the Cre- taceous, but the species is thought by Prof. Ward, to whom it was shown, to be near a species occurring in the Jurassic of the Pacific coast. Concerning the general relations of the fossils from the Kennicott formation Dr. Stanton observes: These fossils are all either Upper Jurassic or Cretaceous, with a suggestion of a somewhat younger age for a few localities. In the present state of knowl- edge and with these small collections it is not practicable to determine whether they represent one horizon or several. In my opinion, they probably all belong to the Upper Jurassic, though subsequent work may show the contrary. The question is connected with the still unsolved problem of the exact boundary between the Jurassic and the Cretaceous in the Aucella - bearing beds of Russia, Siberia, and the Pacific coast region of North America. The Aucella occurring in the Copper River district appears to be referable to a Russian Jurassic species, but it is also quite similar to the Cretaceous form in the lower Knox- ville beds of California. The few other forms are mostly undescribed species of types that occur both in the Jurassic and in the Lower Cretaceous. A single fossil collected on Chititu Creek in 1907 was referred to Dr. Stanton and described by him thus: Chititu Creek : 4S11 ; No. 26— Perisphinctes, sp. This ammonite is not a typical Perisphinctes, but it is probably of Jurassic age, certainly not older than Jurassic. The much larger collection made in 1909 was also referred to Dr. Stanton, who says of them : “ The fossils from the Kennicott indi- cate that one fauna ranges throughout the formation and that its age is most probably Jurassic, though the types represented in the collection are not as definite as could be wished for determining between Jurassic and Cretaceous. The entire absence of Aucella is noteworthy in view of the fact that that genus has previously been reported from the formation.” The list of fossils arranged by lo- calities and with the catalogue numbers of the National Museum follows. McCarthy Creek : 6301— Inoceramus sp. 6313— Lytoceras sp. Phylloceras sp. Base of Kennicott. 40 THE NIZINA DISTRICT, ALASKA, Nikolai Creek : 0302— Inoceramus sp. Base of Kennicott. 6304— Rhynchonella sp. Pecten sp. Base of Kennicott. 6305— Rhynchonella sp. Terebratella ? sp. Exogyra sp. Pecten sp. Collected near 6304. 6307— Phylloceras sp. 6308— Inoceramus sp. Lower part of Kennicott formation. 6309— Rhynclionella sp. Inoceramus sp. 6310— Rhynchonella sp. Terebratella? sp. Base of Kennicott formation. 6331— Rhynchonella sp. Terebratella? sp. Ostrea sp. Rear base of Kennicott formation. Sourdough Hill : 6315— Inoceramus sp. Dan Creek: 6316— Inoceramus sp. 6318- Bowlder in conglomerate of Kennicott formation. Halobia superba Mojsisovics? . Copper Creek : 0322— Rhynchonella sp. Undetermined small Telecypoda. Natica sp. Undetermined ammonite. Base of Kennicott formation. Texas Creek : 6334— Phylloceras? sp. Rex Creek : 6324- Irregular echinoid, crushed specimens. Pecten sp. SEDIMENTARY ROCKS. 41 Rex Creek— Continued. 6324 — Continued. Terebratula sp. Ostrea sp. Anomia sp. Inoceramus sp. Nucula sp. Area sp. Undetermined Gastropoda. Phylloceras sp. Shark’s teeth. Well up in the Kennicott formation. 6425— Serpula sp. Ostrea sp. Pecten sp. Area sp. Cyprina? sp. Corbula sp. Aporrhais sp. Chemnitzia? sp. Crioceras? sp. 6426- Fragment of large ammonite. Higher in the formation than 6324. 6336— Undetermined fragmentary ammonite. White Creek : 6327— Ostrea sp. Upper part of Kennicott formation. 6328— Fragment of large ammonite. High up in the Kennicott. Young Creek : 6329— Cyprina? sp. (fragment). The absence of Aucella from the collections of 1909 raises a ques- tion concerning the Kennicott that can not be answered with the data at hand. If, as seems probable, its absence is due merely to the fail- ure to find it, there is no reason to suspect any difference in age of the Kennicott sediments east and west of Kennicott Glacier. If, on the other hand, it does not occur east of Kennicott Glacier, the pos- sibility that the basal Kennicott beds west of the glacier are older or that the sediments of the two localities are not correctly correlated is apparent. It will be seen from the table of correlation (pp. 26-27) that Jurassic sediments are widespread in Alaska. They are found along the Pacific coast side from southeastern Alaska to the peninsula, and again on the Arctic slope, but are not known in the Yukon Basin. 42 THE NIZINA DISTRICT, ALASKA. Attention is directed more particularly to the Nabesna-White district, the Matanuska and Talkeetna district, and the region of Cook Inl-et and the Alaska Peninsula. The Nutzotin Mountains, northeast of the Wrangell group, consist of a great thickness of banded slates, graywackes, and conglomerates associated with limestone and sandstone beds in minor amount. Upper Jurassic fossils were collected from these beds, but the beds are very imperfectly known, and it is highly probable that they in- clude also Triassic or even older beds. They are exposed in the canyon of Chisana River for a distance of 18 miles, and, although they are much folded, it is evident that their thickness is great. Lower Middle Jurassic and middle and upper Middle Jurassic sediments occupy extensive areas in the region of Matanuska and Talkeetna rivers.® The lower Middle Jurassic rocks have a thickness of 2,000 feet, more or less, and consist of shales, sandstone, and con- glomerate, with coal, associated with andesitic greenstone, tuffs, agglomerates and breccias, rhyolites, dacites, and tuffs. On these was deposited unconformably more than 2,000 feet of middle and upper Middle Jurassic shales, sandstones, conglomerates, tuff, and arkose, with coal. More than 1,000 feet of this is conglomerate. The Jurassic rocks of Cook Inlet and the Alaska Peninsula were studied by Stanton and Martin in 1904 6 and again by Martin in the region of Iliamna Bay in 1909. They include rocks of Lower, Middle, and Upper Jurassic age. The deposits referred to the Lower Jurassic consist chiefly of water-laid tuffs, and are found at Seldovia, on the east side of Cook Inlet* and probably on the west side also. The Middle Jurassic sediments, called by Stanton and Martin the Enoch- kin formation, include shale and sandstone, with a few thin beds of limestone and conglomerate, and reach a thickness of 2,415 feet on the shore of Chinitna Bay. This section does not include the lower part of the Enochkin formation, yet the thickness given represents what is probably the average thickness of the formation. Upper Jurassic sediments succeeded the Enochkin formation. They were first described by Spurr® and received their formation name from Naknek Lake. The Naknek formation includes shale, sandstone, conglomerate, arkose, tuff, and andesite. A thickness of 5,137 feet of rocks belonging to this formation was measured by Stanton and Martin on the north shore of Chinitna Bay. Lower, Middle, and Upper Jurassic deposits thus reach a thickness of 7,500 to 8,500 feet in this region. a Paige, Sidney, and Knopf, Adolph, Geologic reconnaissance in the Matanuska and Tal- keetna basins, Alaska : Bull. U. S. Geol. Survey No. 327, 1907, pp. 16 and following. 6 Stanton, T. W., and Martin, G. C., Mesozoic section on Cook Inlet and Alaska Penin- sula : Bull. Geol. Soc. America, vol. 16, 1905, pp. 391-410. c Spurr, J. E., A reconnaissance of southwestern Alaska : Twentieth Ann. Rept. IT. S. Geol. Survey, pt. 7, 1900, pp. 169-171. SEDIMENTARY ROCKS. 43 It has been seen from the brief description given that the Jurassic section is more nearly complete as it is traced westward from the Chitina Valley. The evidence is too incomplete to draw definite con- clusions, but it appears that about the lower part of Cook Inlet Lower, Middle, and Upper Jurassic sediments are present, that in the Talkeetna and Matanuska district the Lower Jurassic is lacking, and that in the Chitina Valley both Lower and Middle Jurassic are absent. A possible explanation of this condition is that the invasion of the Jurassic sea was from the west and that the successive drop- ping out of the lower members from the stratigraphic section is evi- dence of progress in the eastward advance. This explanation, how- ever, is not the only one, for the lower divisions of the Jurassic may yet be found in the Chitina Valley, or they may have been removed by erosion if ever present. In this connection, also, attention may once more be drawn to the fact that the known Jurassic sediments of Alaska are found on its Arctic and Pacific sides. They have not been discovered in the Yukon Basin. QUATERNARY SYSTEM. PREGLACIAL CONDITIONS. So far as known, the region under discussion was elevated above sea level at the end of Eocene time and has ever since remained a land area. During and after the cessation of the mountain-building proc- esses which raised the land to its present elevation stream erosion was active and well-developed drainage systems were formed, the area and distribution of which were perhaps very much as they are to-day. The topography of the land surface and the arrangement of the smaller drainage lines must, however, have been greatly different from those existing at present. The relief was developed by stream erosion, and in a region of such great relief the streams must have occupied narrow V-shaped valleys, with the spurs between the lateral tributary val- leys overlapping m such a way as to give the streams a somewhat sinuous course around the points of the interlocking spurs. Further- more, there must have been a heavy covering of residual soil and rock waste mantling the ridges. Stream erosion was the controlling factor in the development of the topography up to the beginning of Pleisto- cene time. PLEISTOCENE (“ GLACIAL ”) EPOCH. CHARACTER AND EXTENT OF GLACIATION. A change in climatic conditions inaugurated the Pleistocene epoch, with a lowering of the temperature or an increase in precipitation, or both. Ice began to form in the heads of the more favorably situ- ated vallej^s, and with the gradual accumulation of ice glacial movement was started. The small glaciers which formed in the heads of a great number of separate valleys moved gradually down- 44 THE NIZINA DISTRICT, ALASKA. ward to meet and merge in the main valleys. Three primary glaciers existed within the limits of this district, two of them (in the Kenni- cott and the Nizina valleys) moving southward and one (in the Chitina Valley) moving westward. It is possible that the Pleistocene epoch has been represented in these mountains by more than one great ice advance, with interglacial epochs in which the ice diminished greatly in area and may even have disappeared in large part. No direct evidence has been obtained that this was the case in Alaska, as the last great ice advance oblit- erated all evidence of previous advances. In other mountain regions in the United States and Canada a succession of ice advances has been established, and somewhat similar conditions have probably prevailed in Alaska. The effects of earlier ice invasions may have had an important influence upon the erosion of the deep glacial val- leys of this region, but the immediate effects now remaining, such as the distribution of moraines and glacial gravels, are to be ascribed to the action of the last great glaciers which filled these valleys. As already stated, the dissection of the area in preglacial time had been accomplished by normal stream erosion. Great quanti- ties of soil and rock waste were ready at hand for the glaciers, and these materials were incorporated into the advancing ice tongues and served as abrasives for the glaciers to use in the further grind- ing out of their beds. As they advanced down their valleys they encountered opposition from the spurs which projected into the val- leys, and as the ice was able to override these spurs it was upon them that its erosion was most effective. This selective erosion of projecting bodies of rock was carried on continuously, and the resultant is the broad, U-shaped, troughlike gorge which is recog- nized as the evidence of severe glacial erosion. Erosion in the val- leys, however, was not confined to the removal of overlapping spurs. The rock fragments held in the bottoms of the glaciers and pressed down upon their floors by the weight of several thousand feet of ice formed admirably adapted tools for grinding down the floors and rasping away the walls. * It is impossible to estimate with any degree of accuracy the amount of glacial deepening which the trunk valleys have undergone. The difference in elevation between the mouth of a hanging tributary valley and the floor of the main valley below may be considered to offer a fair basis for estimating this deepening, and in many places this discordance is from 1,000 to 1,500 feet. Some such figure may well represent the depth to which glacial scour has low- ered the larger valleys. At the time of the last great period of glaciation the Nizina re- gion was invaded by an ice flood which covered it to such an extent that the surface relief within the area was not more than 4,500 feet as compared with more than 7,700 feet at the present time. Only SEDIMENTARY ROCKS. 45 the high ridges between the principal drainage lines projected above the surface of the ice streams. The land areas were restricted to narrow, angular masses of irregular outline cut into on all sides by the smaller glaciers, which headed back toward the crests of the divides. An attempt has been made (PL III, in pocket) to outline the land areas which projected above the glaciers. This outline can not be considered as exact, but it must represent with a fair degree of accuracy the areas which stood up above the ice surface. Of the total area of the Nizina special -map (300 square miles) only about 18 square miles remained unglaciated. The depth at which the ice stood in the different valleys can in favorable places be determined rather closely by the present distri- bution of glacial moraines and erratic bowlders and by the shapes of the eroded valley walls. Certain mountains, we know, must have stood above the glaciers, because of the angular, rugged character of their summits, which fail to show the effects of the abrasive action of the ice. Other mountains, we know, must have been overridden by the ice, because of their smoothed and rounded outlines and because of the occurrence on their tops of glacial bowlders of rocks which occur in place nowhere in the vicinity of their present resting places. From such evidence it is found that in Nizina Valley, at Sourdough cabins, the top of the glacier must have stood more than 3,000 feet above the present river flat. CHITINA GLACIER. The Chitina Valley, which extends from the head of Chitina River near the international boundary in a west-northwest direction to the Copper River basin, is the channel which drained all the ice fields from the south side of the Wrangell Mountains as well as those from the north slope of the Chugach Range. Although only one edge of the Chitina Glacier lay within the area of the Nizina special map, it may not be out of place to give here some idea of the size of this ice tongue as a whole. At its maximum it was about 120 miles long in its own valley, and it joined the Copper River Glacier, the length of which below the junction of the Chitina is not known, although it must have been considerable. The ice field had a width for portions of its course of 20 miles and averaged about 12 miles, so that its total area was not far from 1,500 square miles, exclusive of all tribu- tary glaciers. South of this area it was certainly close to 4,000 feet in thickness and may have been much thicker. On account of its great thickness the ice surmounted the divide between Chitina River and Young Creek and pushed to the northwest, covering the ridge between Young and Chititu creeks, so that the northern boundary of this great ice field was here the high mountain ridge north of White Creek. That it completely covered the high divides south of this 46 THE NIZINA DISTRICT, ALASKA. ridge is evident not only from the smoothed Rnd subdued slopes of their summits but from the presence on them of scattered bowl- ders of rocks strange to this immediate vicinity. In Chititu and White creeks there are numerous bowlders of greenstone, although none occurs in place within this drainage basin. Their presence here as well as that of the native copper and silver found in the placer gravels is doubtless due to the transportation of glacial ice, the bowlders in White Gulch having been brought from the east by the Chitina Glacier, and the bowlders in Rex and Chititu creeks either by the same ice tongue or from the north by the Nizina Glacier. Much of the native copper and greenstone of Young Creek was brought in by the Chitina Glacier, although there may be greenstone in place at the head of this creek. There is still a large glacier at the head of Chitina Valley, though little is known of its length or appearance. NIZINA GLACIER. The head of the Nizina Basin is still occupied by a great glacier, which now terminates about 11 miles above the mouth of Chitistone River. The valley below, however, shows strongly the erosion of the former glacier which moved down it. Tributary ice tongues entered the valley from both sides north of the area here considered, but within it the large^ branches all came in from the east. The north- ernmost and by far the most important branch came down the Chit- istone Valley. This stream drains a basin which extends northeast to Skolai Pass and east into a range of high glaciated mountains. That the valley was the outlet for a vigorous glacier is evident from the steep-walled trough through which the stream now flows. The valley floor near the mouth of the canyon is only three-eighths mile wide, but the ice in it once reached a depth of at least 3,500 feet and was able to keep its trough cut down to grade with the floor of the Nizina Valley. Toward the lower end of the Chitistone Valley the tops of the mountains on both the north and the south sides are flat and mesa-like, and, although the valley glacier did not extend up to these mesas, they were occupied by glaciers which must have extended to their edges and cascaded down upon the valley glacier below, so that only a portion of the steep cliffs at the upper limit of the valley walls were free from ice. Five miles south of the Chitistone a tributary ice tongue fed into the Nizina from Dan Creek. This lobe drained the ice from a much smaller basin than the Chitistone and excavated its valley much less severely. In it the depth of the ice was great, but this was due more to the damming back by the great glacier in the Nizina Valley than to its own supply, and the movement must have been comparatively sluggish. Besides receiving ice from a large number of cirques, some SEDIMENTARY ROCKS. 47 of which are still occupied by small glaciers, this lobe was fed by the ice sheet on the mesa to the north. This ice sheet still exists and covers most of the flat uplands, but now sends ice over its edge at only a few points. The main valleys of Chititu and Young creeks were invaded by ice from the Chitina Glacier, which spread over the intervening ridges and made a continuous ice sheet from Chititu Creek to the south side of the Chitina Valley. Rex Creek, however, was separated by a high ridge from the Chitina ice and sent down a tributary tongue to join the great ice flood at the junction of the Nizina and Chitina glaciers. KENNICOTT GLACIER. The Kennicott Basin is occupied in its upper portion by a glacier which extends within 5 miles of the mouth of Kennicott River. The area of the Nizina special map includes about 10 square miles of the eastern edge of this ice tongue. A line drawn from Kennicott to the point of junction of the two principal branches of the glacier sepa- rates the white ice of the east fork from the moraine-covered ice of the lower portion. The west fork, which is the larger, heading on the flanks of Mount Blackburne, shows a banded, ribbon-like surface of lines of white ice alternating with long surface moraines. Below the junction of the two branches the white bands disappear and the glacier presents a chaotic surface of sharp hills and deep, wide- mouthed crevasses, all more or less thickly covered with debris. Part of the drainage from the melting ice runs off as streams, which flank the lower portion of the glacier on either side, but much the greater part of the water emerges from what is known as the “ pothole,” at the lower end of the glacier. The pothole is the mouth of a subglacial channel, and Kennicott River boils out of this opening as a gigantic spring. In winter the pothole has been known to freeze up, damming back the water until sufficient hydraulic pressure has been developed to break away the ice, wdien a torrent of water rushes down Kennicott and Nizina rivers, sometimes flooding the ice all the way to Copper River. The severity of the earlier glaciation in the Kennicott Valley is comparable to that of the Nizina. The ice extended southward to join the great Chitina Glacier, which had already been swelled by the ice from the Nizina. The surface of the glacier at Kennicott then stood about 3,000 feet higher than it does to-day, and the severity of its erosion is shown by the straight lines of the contours along the mountain sides and by the complete absence of projecting spurs. The Kennicott Glacier had within this area one important tributary, which occupied the valley of McCarthy Creek. Its course, like that of the Kennicott and Nizina glaciers, was from north to south, and its erosion was sufficient to reduce its valley to a straight, U-shaped 48 THE NIZINA DISTRICT, ALASKA. trough. Within the area of this map all the important tributaries to McCarthy Creek Glacier came in from the east, especially from the valleys of Nikolai Creek and East Fork. At one time the ice surface stood 1,000 feet above the divide at the head of South Fork of Nikolai Creek, and it is probable that some of the ice from the Nizina Glacier moved westward over this col and then down the McCarthy Creek valley. Below Sourdough Peak the Kennicott, McCarthy, and Nizina glaciers all joined the great Chitina ice stream and moved northwestward down the Chitina Valley. In the preceding paragraphs the attempt has been made to describe the glaciers of the region at the time of their greatest development. The individual ice lobes and their interrelations would have been different at lesser stages of development. The arrows shown on the map (PL III, in pocket) represent the directions of ice movement in the different parts of the area. RETREAT OF THE ICE. In the earlier stages of glaciation of the region the ice no doubt built up lateral and terminal moraines, but further advances de- stroyed or obliterated all traces of the earlier deposits. It is only those deposits that were laid down at the time of or subsequent to the maximum advance of the ice that have been preserved, and in many jilaces even this material has been removed by stream cutting or been covered with stream deposits. There are left only a few areas of distinctive terminal moraine, having the characteristic hum- mock and kettle topography. Some such moraine still exists west of the lower portion of Young Creek, and some east of lower Chititu Creek, with occasional more recent patches like that on Texas Creek near the head of Copper Creek. These areas often contain lakes which occupy undrained depressions in the glacial deposits. The absence of strong moraines in most of the valleys is due, in part at least, to the vigorous cutting of the streams, which have long ago removed them. The Kennicott Glacier, which terminates near the mouth of McCarthy Creek, has remarkably little fnoraine around its edges, and although the surface of the lower portion of the glacier is covered with detritus the streams have removed this as fast as it has been dropped by the ice and in many places are cutting into the glacier itself. Glacial till or bowlder clay is rather widely distributed in this area along the lower slopes of the valley walls. Its surface is gen- erally covered by a heavy growth of mosses and timber, but fresh exposures can be seen at many places along the banks of streams. It consists of a rather dense blue clay in which are embedded bowl- ders, pebbles, and angular fragments of many different kinds of rock, and it is characterized by unassorted materials and lack of stratification. SEDIMENTARY ROCKS. 49 BENCH GRAVELS. As climatic conditions became less favorable for glaciation and the ice diminished from its greatest thickness the glaciers in many of the smaller drainage lines tributary to the larger trunk valleys shrank until they no longer joined the main ice lobes below. Thus the lower part of McCarthy and Dan creek valleys were free from ice while their mouths were blockaded by the Kennicott and the Nizina glaciers. In like manner the ice in the Chitina Valley had shrunk so that it was no longer able to override the ridges on either side of Young Creek, and Chititu and Young creeks had lost their ice while the Nizina Glacier still stood high in the valley to the northwest. As a result the drainage in many valleys was impeded by the ice dams across their mouths, and the streams began to fill in their basins with gravel deposits. It may be that temporary lakes were sometimes formed behind the ice barriers, but the char- acter of the gravel deposited indicates that if such lakes existed they must have been of short duration. Gravel fillings behind glacier dams in many places reached a great thickness. In Young Creek valley, above the portion where the creek flows nofth, the gravels are in places more than 500 feet thick near the center of the valley and thin out at the sides. The upper limit of the gravels is difficult to determine on account of the thick coating of moss with which the surface is covered, but it probably lies for the most part between the elevations of 3,250 and 3,500 feet. In Chititu Creek, at the mouth of Rex Creek, a similar thickness of gravels was reached. At the point where Dan Creek emerges from the mountains a great bench more than TOO feet high shows that the stream floor was graded up to that level when the Nizina Glacier still filled the valley below. In the McCarthy Creek valley a broad area was filled with gravels deposited under similar conditions. An advance by the Kennicott Glacier of only 2 or 3 miles would be sufficient to cause McCarthy Creek to begin again the grading up of its valley with gravels like those of which the gravel benches are composed. In all of the valleys mentioned the alluvial filling was due to the presence of an ice barrier which retarded the drainage and caused the streams to build rapidly. As the great glaciers retreated and their thickness decreased the barriers to the tributary streams were lowered and they began to cut into the gravel filling which they had laid down. They did not, however, remove the filling from the whole width of the valleys, but intrenched themselves in this filling and developed deep gorges with gravel banks. Throughout much of the upper part of Young Creek and in parts of Chititu, Dan, and McCarthy creeks the streams have now cut completely through the 70648°— Bull. 448—11 4 50 THE NIZINA DISTRICT, ALASKA. gravels and into the rock below, leaving the valley filling as terraces or benches on either side of the streams. In Young Creek valley, especially, many lateral tributaries have also cut through the gravels, which now form interrupted benches along the slopes to the north and south of the stream. PRESENT STREAM GRAVELS. The larger glacier-fed streams of the area are in sharp contrast, both in appearance of water and in character of valley deposits, with the streams which do not head in active glaciers. The streams which are supplied only by melting snow and by the ordinary run-off are for the most part clear, and they are gradually cutting their valleys deeper. The glacier- fed streams, on the contrary, are supplied with great quantities of detritus by the glaciers, and during the warm season they are turbulent and heavily loaded, so that they are con- stantly building up their vallej^s with gravels and silts brought down from above. The Nizina Valley is a conspicuous example of this building process. The present flood plain ranges in width from one- fourth mile at the extreme western edge of the area mapped to more than 2 miles at its widest points. The flat is composed of gravel bars, for the most part bare of vegetation though some of the higher portions are timbered. The proportion of the flat that is covered by water at any one time not only varies greatly with the seasons, but often there is a great daily range as well. Since the water supply is largely furnished by the melting of the glaciers and of the snow on the mountains, the streams are highest in July, and in periods of high water a large part of the flat is covered. During the late fall and winter the rivers dwindle until but little water flows beneath the ice. The daily range, too, is largely controlled by the temperature, the streams being lowest in the earty morning but on bright, sunny days increasing in volume until the late afternoon, when the flow is many times as large as it was early in the day. All of these variations in volume are important factors in the trans- portation and deposition of debris. In high stages the streams are most turbulent and great quantities of gravel and silt are carried by them. In low stages the water becomes clearer and but little mate- rial is moved. As a result of their overloaded condition during the summer, the streams, which flow in some places as single streams and in others as intricate networks of channels, are constantly shifting their courses over the flood plains,, building up bars in some places while cutting them away in others. In the Nizina Valley below Young Creek the present tendency of the river is to lower its bed, owing to the increased gradient given by the cutting down of Nizina Canyon below. Above Young Creek the valley floor is being built SEDIMENTARY ROCKS. 51 up, the building proceeding most rapidly at the mouths of the tribu- tary streams. Chititu Creek has a large low-grade fan below its canyon, but the edge of this fan has reached the Nizina flood plain at only one point. Dan Creek also has a low fan extending out to the Nizina bars. The largest deposit from a tributary stream is that at the mouth of Chitistone River. Here a wide fan of low slope has crowded Nizina River over against the rock cliffs on its west valley wall, where in places all the talus slopes have been removed and the flood plain extends flush up against the limestone cliffs. This fan has also been effective in retarding the current of Nizina River above it and in aiding deposition there. McCarthy Creek flows for the lower 10 miles of its course through a more or less narrow valley intrenched into the gravel deposits and into its rock bed, but above this portion the valley floor is broad and gravel filled. POSTGLACIAL EROSION. The agencies of rock weathering and erosion are very active in this region of great daily ranges in temperature, high altitudes, and steep slopes, so that the amount of rock material which has been removed since the retreat of the great glaciers has been large. The timber line throughout the district lies at about 4,000 feet or lower, although willow and alder bushes flourish above this and are some- times found up to an elevation of 5,000 feet. Above 5,000 feet vege- tation is sparse and most of the surface is bare and exposed to the agencies of weathering. Large talus slopes occur below all steep cliffs. The greenstone is perhaps most resistant of all rocks in this vicinity, and the talus accumulations below greenstone outcrops are small as compared with those below similar cliffs of the more easily weathered rocks. The Chitistone limestone follows the greenstone in its ability to resist weathering, although, as is to be expected, there are often large talus slopes below the enormous cliffs which this lime- stone offers. The porphyry weathers much more rapidly than either greenstone or limestone, and the sides of those mountains which are composed of this rock are almost invariably buried beneath great talus aprons. In the steep-sided porphyry mountain between the Kennicott and McCarthy Creek the talus is so abundant that few outcrops occur below an, elevation of 5,000 feet and only the upper craggy portion of the mountain is free from talus. Both Triassic and Jurassic shales weather readily, the latter with the greater ease on account of its freedom from hard beds of limestone. A great amount of postglacial stream cutting has been done in the Triassic shales between McCarthy Creek and the Nizina. In the Kennicott shales of Dan, Chititu, and Young creeks the amount of stream cutting near the gulch heads has been very large. There is 52 THE NIZINA DISTRICT, ALASKA. every reason to believe that on the south side of Chititu and on both sides of Young Creek the slopes were left smooth and free from gulches by the glacial ice. Since the ice retreated large gulches have been cut and a great amount of the easily eroded shale has been removed. The streams in these valleys have also succeeded in cutting through the thick gravels into the bed rock below. Altogether, when the comparatively short time that has elapsed since the retreat of the ice from this area is considered, the work accomplished by erosional agencies has been surprisingly great. ROCK GLACIERS.® Among the important agencies of postglacial denudation in this district are the remarkable features which have been called rock glaciers (PI. Ill, in pocket). These are rather widely distributed among the more rugged portions of the area, more than 30 occur- ring within the borders of this sheet. They are known to occur in other parts of the Wrangell Mountains, but here they attain excep- tionally perfect development. An inspection of the topographic map shows at once many of the characteristics of the rock glaciers, but the important features, such as the surface markings, can not be shown with such a large contour interval. Although differing greatly among themselves in size, shape, and material, they have certain characteristics in common. They are usually long, narrow flows, many times longer than wide, confined in the bottoms of cirquelike valleys. Some have wide, fan-shaped heads and taper down to narrow tongues below; others are narrow above and spread out into spatulate lobes below; but the greater number are bodies of nearly uniform width, from one-tenth to one-fourth of a mile wide and from one-half to 2^ miles long. The surface slopes vary in different examples from 9° to 18° for the whole course of the floiv. On viewing one of the better-developed rock glaciers one is struck by its great resemblance to true glaciers. They all head in cirques and extend thence down the valleys. In crass section their shape is much like that of a glacier, being highest above the valley axis and sloping down sharply on the sides. Where confined in narrow valleys the rock glaciers are narrow tongues lying in the valley bottoms, but upon emerging from their restricting walls they spread out into broad lobes. Some have distinct lateral moraine-like ridges and all show a more or less well-marked longitudinal ridging. The materials of which the rock glaciers are composed are the blocks and fragments of angular rock such as go to make up the ordinary talus slope, the fragments being derived from the walls of the cirque at the valley head. The variety of rock found in any Capps, Stephen R., Rock glaciers in Alaska : Jour. Geology, vol. 18, pp. 359—375. SEDIMENTARY ROCKS. 53 rock glacier therefore depends on the materials found in the cirque walls — porphyry, limestone, greenstone, or shale, as the case may be. The individual rock fragments vary in size from fine stuff to blocks several feet in diameter in exceptional cases. Six inches would per- haps be the average size in these rock glaciers which are composed of porphyry, while in the greenstones and limestones the average is larger and in the shales it is smaller than this. In many of the rock glaciers the fragmental rock extends all the way to the head of the cirque, with no ice visible and little or no snow on the surface. In several cases, however, the rock glaciers grade into true glaciers at their upper ends, without any sharp line of demarcation, so that there is a complete gradation between the two. The surface markings are characteristic and in some measure are systematic in their arrangement. In the upper portions there are usually many parallel longitudinal ridges a few feet high, separated by troughlike depressions (PI. IX, B , p. 56). Toward the lower end of each rock glacier which has an opportunity to spread out into a broad lobe the longitudinal ridges become less prominent and finally disappear entirely, giving place to concentric wrinkles which parallel the borders of the lobe. The sides of the flow below the cirque are usually separated from the rock valley walls by a sharp trough, and at their lower ends the flow T s steepen to the angle of rest for the material. The w T hole appearance gives one a decided impres- sion of movement, as if the material had moved forward from the cirques in somewhat the manner of a glacier, the longitudinal lines simulating moraine lines. The marked resemblance of these flows to glaciers led to the sus- picion that ice must be in some way responsible for their movement. To determine if this were the case, a number of the rock glaciers, 7 or 8 in all, were dug into, and in each instance clear ice was found. This Avas not massive ice like that of a glacier, but interstitial ice, filling the cavities between the angular fragments and forming with the rock a breccia, with the ice as the matrix. The depth below the surface at which ice was found A 7 aried according to the elevation of the rock glacier and to the portion of it examined. Toward their lower ends the ice lay too deep to be found by any shallow excava- tions that there was opportunity to make. Farther up, toward the cirques in which they head, the ice was usually found within a foot or two of the surface if a depression was dug into. The surface of the ice-filled portion, being determined by the depth to which melt- ing takes place, follows roughly the surface of the flow, so that along the. troughs between the ridges running water could be found on a warm day following shallow channels in the ice-filled talus. 54 THE NIZINA DISTRICT, ALASKA. The rock glaciers are quite different from true glaciers, although in those cases where the rock glacier is a continuation of the lower end of a true glacier it may be impossible to draw a line separating the two. For the formation and existence of a glacier it is necessary that in the head of the basin occupied by ice there should be an annual surplus of snowfall over melt. When the amount of snow- fall becomes less than the amount which melts and runs off, the glacier will dwindle and finally disappear. The greater number of rock glaciers, on the other hand, are found to head in cirques in which all or practically all of the winter snow disappears during the summer. In a true glacier, no matter how heavily moraine covered it may be, there is always a tendency to crevasse where the ice rounds a bend or passes over an irregularity of its bed, and great irregularity of surface is common at the lower end, where the melting ice allows the overlying moraine to cave in. In the rock glaciers no crevasses were seen, even in places where abrupt changes in the grade of the bed occur, and large cave-in pits are wanting. Irregularities of this kind, however, are not to be expected if the rock glaciers are com- posed, as they seem to be, of talus, with ice only in the interstices, for the talus itself is self-supporting without the ice, and the shape of the surface would be but little changed if the ice should all melt out. This is true, however, only of those flows which have not glaciers at their upper ends. Of those which head in glaciers, the upper ends would of course be profoundly altered by the melting of the ice, and these effects would be seen just as far down the flow as massive glacial ice had existed. The rock glaciers differ from true glaciers in that, although they advance spasmodically, they never retreat, for the flow retains its form even after the ice has melted out and motion has ceased. Little has been published concerning features of this kind. Certain “ stone rivers” in the Falkland Islands have been described by Thomson , 0 Andersson , 6 and others, but according to Andersson’s interpretation these “ stone rivers,” which are now streams of angular blocks of rock, were formerly composed of fine mud, with the blocks of rock buoyed up and carried along by the viscous flow of the mud. The movement has now ceased, and much of the fine material has been removed by running water. The closest analogy to the rock glaciers seems to be found in the “ rock streams” of the San Juan Mountains of Colorado, described by Cross and Howe 0 in the Silverton folio and more recently by Howe 3 in a separate publication. Both are composed of angular a Thomson, Wyville, The Atlantic, p. 245. b Andersson, J. G., Solifluction, a component of subaerial denudation : Jour. Geology, vol. 14, 1906, pp. 91-112. c Cross, Whitman, and Howe, Ernest, Silverton folio (No. 120), Geol. Atlas T T . S., U. S. Geol. Survey, 1905, p. 25. d Howe, Ernest, Landslides in the San Juan Mountains, Colorado : I'rof. Paper U. S. Geol. Survey No. 67. 1909. SEDIMENTARY ROCKS. 55 talus from high mountains, and the similarities of appearance and surface configuration are striking. The San Juan flows have been referred to in a textbook a as “ talus glaciers,” and the authors are of the opinion that in many cases snow and ice have had some part in their development. Cross and Howe formerly believed that the posi- tion and form of the rock streams were due to glacial transportation, but the absence of ice and some other considerations led them to the opinion which they now hold, that the rock streams were formed by landslides which came down a with a sudden violent rush that ended as quickly as it started.” Up to the present time no oppor- tunity has offered to prove conclusively by a series of observations extending over a considerable period of time that these rock glaciers are in motion or to determine their rate of movement. There are, however, a number of significant facts which seem to make this con- clusion necessary. Although on account of climatic conditions most of the cirques in which the rock glaciers head are unable to support true glaciers, they are on the border line of glacial conditions, and although the snows may all melt away on the surface during the summer the ground remains permanently frozen a short distance below the surface and ice in the interstitial openings of a talus mass may remain unmelted indefinitely. Furthermore, a few of the rock glaciers have true glaciers at their heads which extend downward as far as climatic conditions are favorable and are continued below by rock glaciers whose ice is protected from the sun by the heavy coating of debris, and into such rock glaciers it is probable that a tapering tongue of true glacial ice extends down a considerable distance. But this glacial ice is not necessary to their movement, as is shown by those rock glaciers which are unconnected with true glaciers. In addition to the favorable climatic conditions, the exceptionally perfect develop- ment of these features in the Nizina district is due to the rugged character of the mountains, with cirques having steep heads and sides, and to unusually favorable conditions for rapid rock weather- ing and talus accumulation. The history of the rock glaciers of this district is considered to have been as follows: As the ice of the last great epoch of glaciation began to retreat and its area to contract, the head and side walls of many of the cirques, steepened by glacial undercutting and by bergschrund sap- ping, were exposed to the rapid weathering characteristic of bare rock surfaces in the high altitudes of this region. In many of the cirques the rock waste streamed down from the cliffs upon the glacier below and was gradually carried away by the ice and con- centrated at its lower edge. Here in the usual order of events it Chamberlin, T. C., and Salisbury, It. D., Geology, vol. 1, 1904, p. 220. 56 THE NIZINA DISTRICT, ALASKA. would have been deposited as a terminal moraine, though differing in character from the common forms of terminal moraine in the preponderance of angular, talus-like material and in the propor- tionately smaller amount of mud and rock flour which form so im- portant a part of the moraines of active glaciers. Here the small, fast-dying glaciers were eroding but little and were almost over- whelmed by the debris supplied them from the cliffs above. Into the debris toward the lower edge of the glacier the waters from melting ice and snow and from rains sank and froze and gradually filled the interstices up to a point below the surface where melting equaled freezing. In these ice-cemented masses a sort of glacial movement was started. As the climate became still milder, in many cirques the winter snows all melted away during the summer, so that conditions for ordinary glacial activity no longer existed, but the bodies of talus which reached the cirque floors became filled with interstitial ice and the consequent movement of the mass in a glacier- like way has continued, although no doubt all true glacial ice has now disappeared from many of the rock glaciers. It is certain that much snow is still carried down upon the surface of the rock glaciers in slides of snow and rock during the winter and spring, and con- siderable quantities of it may become covered by debris and incor- porated into the rock glaciers, but this snow probably forms only a small part of- the total mass of the flow. The succession of events outlined seems to be well established in this region, where are now to be seen all the stages, varying from apparently active glaciers with short rock glaciers below to long rock glaciers in which no glacial ice is seen, in valleys where all the snow disappears during the summer; yet in these latter the slow movement seems still to be in operation, the rate of movement in each flow being controlled by the supply of talus from above and by the shape and grade of the floor over which it moves. The rock gla- ciers are therefore the true successors of real glaciers. The rock glacier which lies on the west side of McCarthy Creek, three-fourths of a mile above the mouth of East Fork (PI. VIII), though by no means the largest in size, offers a most instructive example for study, as it presents in a typical way many of the char- acteristic features of all of the flows. It heads in a glacial cirque in a mountain composed largely of porphyry but having many inclosed masses of black shale, the peaks at the cirque head reaching a height of 6,315 feet. The rock glacier occupies the cirque floor below an elevation of 5,250 feet, with talus slopes extending upward above it for about 200 feet. Above the talus the whole face of the mountain is of bare, rugged cliffs of porphyry and shale, both of U. S. GEOLOGICAL SURVEY BULLETIN 448 PLATE VIII ROCK GLACIER ON McCARTHY CREEK THREE-FOURTHS OF A MILE ABOVE MOUTH OF EAST FORK. Showing the source of supply in the talus cones above, also the surface markings — longitudinal in the upper portion, concentric below. See page 56. SEDIMENTARY ROCKS. 57 which weather easily, so that the formation of talus is unusually rapid. The elevation of the valley head is not sufficient for the maintenance of a true glacier, and during the summer practically all of the snowfall disappears. By July 4, the time of observation, only small snow banks remained in sheltered places. The rock glacier heads in the talus cones which have been built up at the base of the steep rock cliffs. These cones, although constantly added to by waste from the rapidly weathering cliffs above, have nowhere been able to attain large size, the materials evidently hav- ing moved on down the valley as a rock glacier as fast as they were supplied from above. From the base of each of the more vigorous talus cones a smooth ridge extends down the rock glacier, seeming to show that the forward movement has on the whole been uniform and continuous. Parallel longitudinal ridges of this kind charac- terize the surface of the upper three-fourths of the flow. The cirque basin above an elevation of 4,000 feet is a hanging valley, but below this level it joins the broad U-shaped valley of McCarthy Creek with an abrupt change of gradient. As it passes over the lip of the hanging cirque the rock glacier cascades steeply down the valley side, and on reaching the gentler slope below, being no longer con- fined by restricting valley walls, it spreads out in a great lobe along the valley bottom. In this lower lobe the longitudinal surface mark- ings dwindle out and disappear, giving place to a set of beautifully developed concentric wrinkles which parallel the borders of the lobe (PI. IX, B ). The origin of these wrinkles is not clear, but they strongly suggest rings of growth and may represent the amount of annual movement of the rock glacier. At its foot the flow has pushed across the valley bottom to the base of the east valley wall, thus indicating clearly by its position that it was formed after the retreat of the McCarthy Creek Glacier beyond this point. The creek has been crowded to the east and occu- pies a narrow channel between the foot of the rock glacier and the rock valley wall. The foot of the flow is being rapidly cut away by the stream and in places shows a face 75 to 100 feet high in which the slope is about 35°, or the angle of rest for the material. The creek, although of large volume and steep gradient, has been unable to do more than keep its channel open along the foot of the rock glacier, and it seems evident that the flow is moving forward as fast as the stream can cut it back. Another rock glacier which heads in the same porphyry-shale mountain as the one just described flows in a northwest direction into the valley of National Creek, a tributary of the Kennicott (PI. IX, A). It is remarkable for the unusually strong development of the 58 THE NIZINA DISTRICT, ALASKA. longitudinal ridges in its upper portion, and these ridges show well their mode of origin in the separate talus slopes on the rock walls above. The flow in Amazon Creek, just east of the Kennicott Glacier, and that in the north head of White Creek are notable for their great length as compared with their width and for the uniformity of their slopes from one end to the other. The surface of the former has a slope of 15° and that of the latter 12°. The rock glacier which heads in the limestone mountain half a mile northeast of the Bonanza mine and flows eastward shows at its upper end all of the characteristics typical of these flows, but at the mouth of the hanging valley in which it lies it streams down to McCarthy Creek as a symmetrical talus cone (PL X, A). If the material had come down suddenly as a landslide, no such per- fect talus cone would have formed, and its presence indicates that the material of which it is composed was supplied slowly. Further- more, evidence that this rock glacier is still moving is given by the fact that the talus is still being supplied at the head of the cone and is invading the patch of bushes on its side. The two large rock glaciers, one on the south and one on the north- west side of Sourdough Peak, are both of the type which originates in narrow cirques but spreads out into broad lobes below the point where the cirque walls restrict it. The glacier on the south side of this mountain is especially noteworthy on account of the great expanse of the flow below as compared with the narrow limits of the cirque in which it originated. In conclusion, observation has led to the belief that these rock glaciers have moved and that many of them are still moving in much the same way as glaciers, and that, although glacial ice may be and doubtless is present in a few of them, it is not necessary to the move- ment, which may be due altogether to ice in the interstices. Further- more, there is no evidence that the flows came down suddenly as land- slides, but there are strong reasons for believing that they moved down slowly. The facts and considerations which have led to the conclusion that the flows did not come down suddenly but slowly and that some of them are now in motion are noted below. 1. The remarkable resemblance in position and form of the rock glaciers to true glaciers in the immediate vicinity. 2. The direct connection and perfect gradation between true gla- ciers above and rock glaciers below. 3. The presence of interstitial ice at no great depth below the sur- face in all the rock glaciers which were dug into. 4. The longitudinal ridges of the upper portions of many of the flows that can be traced directly to active talus slopes. U. S. GEOLOGICAL SURVEY BULLETIN 448 PLATE X A. ROCK GLACIER IN A TRIBUTARY OF McCARTHY CREEK NORTHEAST OF BONANZA MINE. At the mouth of its hanging valley it breaks down into a great talus cone. See pages 58, 59. B. DETAIL OF SURFACE OF ROCK GLACIER ON TRIBUTARY OF McCARTHY CREEK. The rounded ridges in the foreground are the concentric ridges which characterize the lower portion of the flow. SEDIMENTARY ROCKS. 59 5. Nowhere have the talus slopes at the cirque heads been able to form any considerable accumulations upon the surface of the rock glaciers. This seems to be strong evidence that the talus has moved down valley as fast as it has been supplied. 6. Most of the rock glaciers have a steep slope at the lower end. where the gently sloping surface of the upper portion breaks down at the edge at an angle of rest as steep as the material will retain. On this steep face the rock fragments show bare surfaces, while the talus on the surface above is usually lichen covered. This seems to show that the material is moving forward fast enough to prevent erosion at the lower end from establishing drainage lines on the face of the flow and from reducing it to a low-graded slope. 7. McCarthy Creek, a swift stream of large volume, which is now actively cutting into the lower edge of a rock glacier on its west side (described on pp. 56-57) that has been in existence long enough for large spruce trees to grow upon its surface, has so far been unable to do more than keep open a narrow channel along the foot of the flow. There is no evidence that the rock glacier ever extended 75 feet farther eastward to the rock bluff on the east side of the valley. It would be surprising if this mass of material, coming down with a violent rush, should have failed by just the width of the creek to cross the valley, and if the stream, which is now actively cutting into the face of the flow, should have been unable to do more than keep its channel open. It appears more probable that the slowly advanc- ing edge of the rock glacier had forced the stream to its present posi- tion and that the edge of the flow is now farther advanced than it has ever been before. 8. There is no evidence that large landslides have taken place in this region if these flows are not landslides. None were seen below the miles of prominent cliffs of the area, though ordinary talus cones are abundant. 9. The rock glacier on McCarthy Creek, northeast of the Bonanza mine (PI. X, A and B ) , ends below in a well-developed talus cone. If the material had come down suddenly as a landslide, no such per- fect talus cone would have been formed. The presence of the cone indicates that the material was supplied slowly, enabling the cone to grow symmetrically. The cone is still growing, as can be seen from the way in which the talus from above is invading the patch of bushes on its face. 10. Wherever two rock glaciers from adjacent cirques join to form a single flow the point of junction shows that the two branches have flowed together synchronously, without any evidence that the flow from one branch has come down and overridden that from the other. 60 THE NIZlNA DISTRICT, ALASKA. IGNEOUS ROCKS. TRIASSIC OR PRE-TRIASSIC. NIKOLAI GREENSTONE. CHARACTER OF THE FORMATION. The Nikolai greenstone resembles a sedimentary formation in its structural features. It is made up of flows of basaltic lava that suc- ceed one another like beds laid down in water. The beds or flows are usually of considerable thickness, measured in tens of feet rather than in single foot units, and the bedded appearance is more evident when a large mass of the greenstone is seen from a distance great enough to give a comprehensive view of its larger features. The color of the weathered surface is grayish green, but in places it has a reddish hue. A fresh surface is dark olive or grayish green. In texture it varies from a dense, rough, fine-grained rock in which individual crystals can not be distinguished to a medium-grained porphyritic rock. Many of the flows are amygdaloidal and have a spotted appearance, due to the cavity fillings. Some of the spots or amygdules are light gray or almost white, like quartz or calcite; others are dark green or gray. Quartz is present but is not so fre- quently seen filling cavities as calcite, yet these two minerals are not the only ones that produce light-colored amygdules. Amygdaloidal greenstone bowlders in Chititu Creek contain large spherulitic aggre- gates of white crystals, believed to be thomsonite. This rock, how- ever, was not seen in place. Dark-colored amygdules are more com- mon than the light ones and for the most part consist of chloritic or serpentinous material. In many places the cavities of the lavas were elongated and distorted before their present mineral filling was introduced, so that the amygdules have peculiar irregular forms. The cavities appear to have been distributed throughout the flows from top to bottom, for no evidence of their being more abundant at the upper than at the lower surface was observed. This is one of the reasons for suspecting that the lava was poured out under water, since the weight of the water resting on the surface of the lava would prevent in large measure the expansion of included gases or steam; vet it is admitted that no proof of their submarine origin has been discovered. Interbedded tuffs and shales were not found in the greenstone. Frequently a weathered surface of the greenstone is seen where the amygdules have been dissolved out, leaving a vesicular rock that probably resembles closely the original lava flow. A newly broken surface of the greenstone would hardly lead one to believe that chemical alteration had taken jflace to any consider- able extent, for the rock appears to be fairly fresh, yet microscopic examination of the sections shows that the alteration is advanced and is general. IGNEOUS ROCKS. 61 The Nikolai greenstone is less obtrusive in its topographic expres- sion than either the shales or the limestone. It forms steep slopes and ragged mountain tops, but the greenstone mountains do not possess the sharp, angular outlines of the shale mountains or the high wall-like cliffs and the pointed spires of the limestone. Neither do the lower greenstone hills present the smooth, rounded contours of the glaciated shale ridges on either side of Young Creek. The green- stone resists decay, but it has numerous joints and fracture planes and rapidly breaks down under northern climatic conditions. This accounts for the roughness of its ridges, the absence of smooth perpen- dicular cliffs, and the vast quantity of angular blocks below its large exposures. Such blocks do not disintegrate like the shales, so that greenstone pebbles and bowlders form a conspicuous proportion of the gravels and other unconsolidated deposits. The greenstone, like the Chitistone. limestone, resisted strongly the distorting forces that are so plainly expressed in the folding of the McCarthy shale. There is even less evidence of folding than in the limestone, but it is apparent from field observations that adjustment to pressure by faulting has taken place extensively. PETROGRAPHIC DESCRIPTION. Thin sections of greenstone studied with the microscope show that the rock is a typical diabase now much altered. The principal con- stituents are feldspar and colorless pyroxene. The feldspar is labra- dorite, occurring in lath-shaped crystals, and in nearly every section is more or less altered. Pyroxene fills the spaces between the feld- spars. It has been less resistant to alteration than the feldspar and is largely altered to a serpentinous or chloritic material. Accessory minerals are magnetite or ilmenite and chalcopyrite ; olivine and iddingsite are rare. The principal alteration minerals are serpen- tine or chlorite, calcite, and perhaps quartz. Cavities in the greenstone were abundant, but have been filled with secondary minerals such as chlorite, delessite, calcite, and, rarely, quartz. Many of the amygdules show an outer coating of chloritic material and an inner filling of radiating delessite crystals, in some sections associated with calcite. An opaque decomposition product is common. DISTRIBUTION. The Nikolai greenstone underlies conformably the Chitistone lime- stone and took part in the folding and faulting that the lower part of the limestone underwent. Its distribution, therefore, is related to that of the limestone, and most of its outcrops represented on the map lie in a narrow belt on the south of the limestone belt that is practically continuous and extends southeastward from the north- 62 THE NIZINA DISTRICT, ALASKA. west corner of the mapped area to the head of Texas Creek. This belt has its greatest width on Nizina River. A branch extends east- ward up Chitistone River and then southeastward into the valley of Glacier Creek, a northwestward-flowing tributary of the Chitistone just beyond the eastern limit of the area mapped. The ridge be- tween Dan and Glacier creeks is capped by a broad, flat syncline of limestone pitching gently northwest, but the base of this ridge wherever it is exposed is greenstone. Greenstone is exposed on both sides of Chitistone River. It dips below the gravel floor of Nizina River north of the Chitistone but rises to view again on the west side and continues north half a mile or more till it is cut off by a fault beyond the limits of the area mapped. In places only a veneer of conglomerate or shale of the Kennicott formation covers the Nikolai greenstone and small isolated patches of the greenstone appear where the thin covering has been removed. Such patches are seen about National Creek and south of Nikolai Creek. Two small patches of greenstone appear as islands in the gravels of Nizina River, and another, exposed through faulting and erosion, lies on the north side of Copper Creek. THICKNESS. It is impossible to determine the thickness of the Nikolai green- stone from observations in the area under consideration, for nowhere within this area is the base of the greenstone exposed. Furthermore, it is not certain that the base of the greenstone is exposed in other parts of Chitina Valley, although it is reported in the Chitistone River basin, and it seems probable that certain tuffaceous and shale beds in the Kotsina Valley may represent it. The figures to be given represent, therefore, only that part of the formation exposed immediately below the Chitistone limestone — that is, the upper part. One of the best localities for measurements is on the east side of Nizina River, just north of Dan Creek. The dip of the limestone and greenstone is low to the northeast. Unless the greenstone is reduplicated by faulting, its thickness at this locality is at least 4.000 and possibly 5,000 feet. The conditions for measure- ment in the mountain on the west side of Nizina River are less favor- able, but there appear to be not less than 4,500 feet of greenstone exposed there. About 2,000 feet are exposed on the east, side of Mc- Carthy Creek and 3,500 feet in the ridge on which the Bonanza mine is situated. Between Bonanza Creek and Kennicott Glacier a thickness of over 4,000 feet of greenstone is exposed. Faults are difficult to locate in the greenstone unless some of the other forma- tions are present to give a clue to their existence, and it is recognized that faults of sufficient importance to impair the value of the meas- urements given may have escaped notice. It is highly probable, IGNEOUS ROCKS. 63 however, that the thickness of greenstone in the Nizina district ap- proaches 4,500 feet, and there can be little if any doubt that it is over 4,000 feet. Schrader and Spencer estimated roughly the thickness of the Nikolai greenstone in the upper part of Ivotsina Valley at 4,000 feet.° AGE. Inasmuch as the Nikolai greenstone is composed of lava flows and so far as known does not contain intercalated fossil-bearing beds, the determination of its age depends on its relation to the formations with which it is associated. The greenstone may perhaps contain intruded sills of rock similar in composition to the flows, but for the most part it is made up of lavas that were poured out before the Chitistone limestone began to be deposited. It can not therefore be later than Upper Triassic. Unfortunately no evidence has been collected to fix a lower age limit. North of the Nizina district, in the valley of Skolai Creek and about Skolai Pass and the head of White River, the massive upper Carboniferous limestone is overlain by thin shale beds, tuffs, and lava flows. These overlying beds are believed to rest on the limestone conformably. The lava flows in- crease rapidly in amount as the succession is followed upward until they finally predominate. There is a possibility that the Nikolai greenstone represents the upper part of these lavas overlying the Carboniferous limestone, in which case their age would be Triassic. Brooks and Kindle have presented evidence to show that Triassic sediments along the upper Yukon rest conformably on limestone of the same age as the limestone on White River. & There is therefore some degree of probability that a similar relation of Carboniferous and Triassic formations of the Wrangell Mountains may sometime be established. A comparison of the Nikolai greenstone with the rocks south of Chitina River is of interest but throws little light on the age of the greenstone. The rocks south of the Chitina are chiefly sediments, schists, graywackes, and limestones, all much meta- morphosed rocks. Their age is not known but they are usually referred to the Paleozoic. The degree of alteration in them is far greater than in the greenstone, and if this fact may be used as evi- dence the greenstone is considerably younger. With our present knowledge it is hardly possible to say anything more definite con- cerning the age of the greenstone than that it is older than the Chitistone limestone and probably is Triassic. ° Schrader, F. C., and Spencer, A. C., The geology and mineral resources of a portion of the Copper River district, Alaska: Special publication of the U. S. Geol. Survey, 1901, p. 42. b Brooks, A. H., and Kindle, E. M., Paleozoic and associated rocks of the upper Yukon, Alaska : Bull. Geol. Soc. America, vol. 19, 1908, p. 305. 64 THE NIZINA DISTRICT, ALASKA. JURASSIC OR POST-JURASSIC IGNEOUS ROCKS. QUARTZ DIORITE PORPHYRY INTRUSIVES. LITHOLOGIC CHARACTER. Light-colored porphyritic intrusive rocks are abundant in the Kennicott formation and are confined almost entirely to that for- mation, for it is a remarkable fact that intrusives are rare in the Triassic sediments and the greenstone. These intrusive rocks occur in the form of laccoliths, dikes, and sills. They show considerable differences in texture and vary from fine-grained, almost aphanitic phases to distinctly granular phases in which larger crystals or phenocrysts of feldspar and quartz are included. The color, too, varies from almost white to creamy w T hite and various shades of gray and brown. Small phenocrysts of quartz with perfect crystal outlines are common, but as a rule the more abundant feldspar crys- tals are less distinct owing to chemical alteration that has taken place. It seems rather remarkable that the rock should be so fine grained as it is in some of the larger intrusives and that it should have had so litle effect on the shales into which it was intruded. The porphyries show many stages of alteration, from intrusions that look perfectly fresh to those in which the feldspars are almost wholly decomposed and the rock has a dull, lifeless appearance. A curious banded arrangement of alteration products was noted in some of the light-colored, fine-grained intrusives. Different stages in the advancement of alteration are indicated by concentric zones of yellowish-brown and white color, which show that the chemical changes proceeded in an orderly way from the surface toward the center of each joint block. In many places large masses of black shale have been caught up in the body of an intrusive and stand out in a most conspicuous way against the lighter-colored porphyry background (PL XI, A). Some of these intruded shale masses are half a mile in length along their outcrops and give the appearance of thin shale beds between very thick porphyry sills. In general, however, the included shale masses are much smaller. The porphyries resist decomposition but readily break down into slabs and angular fragments which give rise to extensive talus slopes, or “ rock slides,” as they are locally called. Such debris, because of its light color and its resistance to decay, gives character to slopes of loose material, and, although the dikes or sills from which it came may form only a minor portion of the rock mass, it almost completely hides the presence of shale or other kinds of rock. Dikes and sills are numerous but present no unusual features fur- ther than that some of the sills persist for long distances and in BULLETIN 443 PLATE XI NORTH END OF PORPHYRY PEAK, SHOWING INCLUSIONS OF B. PORPHYR1TIC INTRUSIONS IN BLACK SHALE OF KENNICOTT BLACK SHALE IN PORPHYRY. FORMATION ON McCARTHY CREEK. IGNEOUS ROCKS. 65 places take the form of long overlapping lenses. There is a marked tendency for the intruded rock to follow bedding planes rather than to cut across the beds, so that the sills are more numerous than dikes. Some of the sills in the black shales on the south side of Copper Creek valley continue uninterruptedly for several miles and are such dis- tinct features that the prospectors have given them numbers, as the first, second, etc. They vary in thickness from a foot or two to 100 feet and give valuable aid in determining structure in the shales. Figure 4.— Diagram showing the overlapping of lenticular porphyry sills in the black shales south of Copper Creek. Some of the lenses are 10 to 15 feet thick. A good example of the way in which the porphyry dikes cut the black shales is given in Plate XI, B. (Se6 also fig. 4.) PETROGRAPHIC DESCRIPTION. Microscopic examination of thin sections of the porphyry intru- sives shows that perfectly fresh unaltered specimens are hardly to be found and that alteration products are practically always present. The rock has a fine-grained groundmass consisting chiefly of feld- spar more or less altered and a little quartz in which are phenocrysts of feldspar and quartz. Various degrees of crystallization appear in the groundmass, but its perfection may be obscured by chemical alteration that has taken place since the magma consolidated. One or two of the sections studied are from specimens in which crystalliza- tion had not proceeded far when it was interrupted by cooling of the intrusive rock. These sections show a fine-grained groundmass, almost isotropic, filled with tiny forked skeleton laths or crystals of feldspar. Most sections, however, show a more advanced degree of crystallisation. The feldspar is of the more acidic plagioclase variety. Zonal phenocrysts give an opportunity to determine that they belong mostly to the oligoclase-andesine series. Ortlioclase appears in a few specimens. Quartz in rounded plates or with embayments is not uncommon, but for the most part the outlines are sharp and angular. Brown mica is usually present, as are also shreds and scales of color- less mica. Hornblende is the next most common ferromagnesian mineral. Many of the crystals are much altered, and in some sections the former presence of hornblende is known only by the decomposi- tion products taking the form of the characteristic hornblende cross section. Pyroxene was found in one specimen. Most sections show a black metallic mineral like magnetite and brown iron-oxide stain. 66 THE NIZINA DISTRICT, ALASKA. Alteration begins in the feldspars and results in the production of fine scales of a highly refractory mineral, probably muscovite, that appear in fractures and along some of the zonal bands of the phenocrysts. Calcite is a common secondary mineral and results from the decomposition of hornblende and of feldspar, yet it may have been introduced in part by circulating water. Calcite resulting from decomposition of hornblende is associated with iron oxide. DISTRIBUTION. Porphyritic intrusions are present in the black shales of the Ken- nicott formation in all parts of the Nizina district, but they have their greatest development north of Nizina River. Porphyry Peak and Sourdough Peak are composed largely of porphyry, as is also the mountain north of Nikolai Creek. The upper parts of all three are made up almost entirely of porphyry in which are included masses of black shale. These laccoliths form a hard resisting cap on the softer shale base and doubtless have been an important factor in protecting the shale from erosion. There are no such large por- phyry masses in the black shales southeast of Nizina River, but sills and dikes are numerous in all the shale mountains from Dan Creek to Young Creek. They appear to be more numerous on Dan and Copper creeks and about the head of Rex Creek than they are far- ther south, but the steep, bare sides of the mountains in the former locality give better opportunities for discovering them than the lower timber and moss-covered slopes of the latter. The preference shown by the intrusives for the black shales is considered as evidence that the molten rock was able to force itself into the black shales more easily than into the lower formations or the upper part of the Ken- nicott formation. It is remarkable, when one considers their num- ber in the Kennicott formation, that so few intrusives are present in the Triassic sedimentary formations and the greenstone. Special attention was given to this point during the course of field work, since it was assumed that the intruding rocks must cut the older formations in order to reach the overlying younger formations and that traces of some of the conduits through which the melted rock rose would be found. A few dikes were discovered, but they do not seem to bear any proper relation in size and number to the amount of intruded matter in the shales, so that one is forced to conclude that the intrusives entered the shales through some channel not exposed. AGE. Intrusives in the Kennicott formation can not be older than the rocks into which the } 7 are intruded. Consequently they can not be older than late Jurassic or possibly early Cretaceous. No evidence bearing on their upper age limit was discovered in the Nizina district. It is perhaps true that the intrusions did not all take place at one time, STRUCTURE. 67 and there might be cited as bearing on this point the fact that there is considerable variation in the composition and alteration of the intruded rocks. These two facts, however, are not in themselves proof. Such evidence as the intersection of one dike or sill by an- other dike or sill was not found, and it seems probable that the quartz porphyry intrusions belong to one period of intrusion. Paige and Knopf have presented evidence to show that the quartz diorites of the Talkeetna Mountains are later than Middle Jurassic but younger than the late Jurassic, and state that they are “ thus contemporaneous in a general way with that great series of batho- lithic intrusions of late Mesozoic age which affected the entire Cor- dilleran region from the Straits of Magellan to the Seward Peninsula of northwestern Alaska .” 0 Quartz diorites of equivalent age intrude Upper Jurassic sediments in the Nutzotin Mountains northeast of the Wrangell Group. & There is a strong presumption that the quartz diorite porphyries of the Nizina district are but one manifestation of a disturbance that was widespread and of much greater importance in many other localities than it was here. STRUCTURE. Reference has already been made in the descriptions of the different formations to most of the structural features of the district, but for the sake of clearness these facts are here brought together in one section. Examination of the geologic map (PI. Ill, in pocket) shows that in a general way the formations lie in zones extending in a northwest-southeast direction. Two sections are placed on the map to interpret the structure of these formations. They show that the prevailing dip of the formations below the Kennicott is toward the northeast but that the prevailing dip of the Kennicott itself is toward the southwest, and, further, that in consequence of the greater dis- turbances that have taken place in the older formations their general dip is considerably greater. Section A-A shows the synclinal struc- ture of the Nikolai, Chitistone, and McCarthy formations along the northern boundary of the mapped area west of Nizina River. A parallel section northeast from any point on Dan Creek to Chitistone River or Glacier Creek would have shown this synclinal structure but with the syncline much flattened out, and a comparison of such a sec- tion with section A-A and the map would show that the synclinal axis pitches gently northwest. Section A-A also shows the uncon- formable relation of the Kennicott to the older formations, its com- paratively low southwesterly dip, and the fault that here displaces the basal beds of the Kennicott and the Nikolai greenstone. Section ® Paige, Sidney, and Knopf, Adolph, Geologic reconnaissance in the Matanuska and Talkeetna basins, Alaska : Bull. U. S. Geol. Survey No. 327, 1907, p. 20. b Moffit, Fred H., and Knopf, Adolph, Mineral resources of the Nabesna- White district, Alaska : Bull. U. S. Geol. Survey No. 417, 1910. 68 THE NIZINA DISTRICT, ALASKA. B-B shows the Kennicott formation dipping* gently to the southwest in broad open folds. The southwest dip is small but is sufficient to bring the interbedded shale and sandstone forming the upper part of the Kennicott formation well down on the slope of the mountains south of Young Creek, although these beds appear only on the tops of the high mountains south of Copper Creek and about the head of Rex Creek. At the northeastern end of this section the greenstone and the limestone lie almost horizontally, but a displacement has taken place by which the limestone is brought into contact with the black shale of the Kennicott formation, and it appears that near the fault plane the limestone dips to the southwest or toAvard the fault. Faulting is of common occurrence in the Nizina district, but with the exception of the fault shown on the two sections most of the dis- placements are comparatively small in amount. The great fault just referred to is a strike fault — that is, its trend is the same as the pre- vailing strike of the formations and it extends from Copper Creek northwestward to McCarthy Creek. From work done in previous years it is known that this great fault continues westAvard beyond the Kennicott Glacier, but its course there has not been traced. Good opportunities for studying the fault were found at tAvo locali- ties, one on the South Fork of Nikolai Creek and the other on Dan and Copper creeks. The north slope of the South Fork of Nikolai Creek is a dip slope formed by a thin veneer of basal Kennicott beds resting on greenstone. (See section A— A, PL III.) The south slope shoAvs the basal Kennicott in the creek with a narrow belt of greenstone above it and above the greenstone a great thickness of Kennicott dipping to the soutlrwest. The Kennicott and Nikolai formations in this locality were displaced by a fault in such a way that the rocks on the south side now have a relatively higher position than those on the north side. The fault dips high to the northeast and the displacement is about 800 feet. Very different conditions prevail on Dan and Copper creeks. Section B-B, Plate III, shoAvs that the north slope of Dan Creek is formed of Nikolai greenstone and Chitistone limestone lying in a practically horizontal position. This condition does not hold on the south side; instead a great block of limestone abuts against black Kennicott shales and forms the point of the obtuse angle between Dan and Copper creeks. In this locality the displacement involves a raising of the north side relatively to the south side, exactly the reverse condition from that in the Nikolai Creek locality. This fault dips about 60 ° NE. on Dan Creek and, although complicated by minor cross faults, has a displacement that seems to be nearly or quite the thickness of the Chitistone limestone. The same relative movement as that on Dan Creek took place on the tAvo sides of the fault on the Avest side of Kennicott Glacier — that is, the formations on the north side were raised — yet no direct evidence STRUCTURE. 69 was discovered to prove the existence of the fault between the glacier and McCarthy Creek. Faults of this kind in which the relative movements of the two walls are opposite in direction at two different localities are known elsewhere, yet, inasmuch as the gravels of Nizina River prevent the demonstration that the Dan Creek fault is continuous with that of Nikolai Creek, it should be stated that the conditions described might result from the dropping of a block between two parallel faults, in which case we should be dealing not with one but rather with two faults. No evidence was seen in the field to raise a suspicion that two closely spaced faults occur here. A perpendicular fault almost parallel with the Dan Creek fault traverses the Young Creek valley, and a third, whose strike is more nearly east and west, crosses Nizina River a short distance north of the limits of the area mapped. The Young Creek fault is probably of the same order of magnitude as that of Dan Creek but is more difficult to study, since only one for- mation is concerned in the localities where it was examined. It has a known horizontal extension of 5 or 6 miles and the zone of dis- turbance is a wide one. These displacements, however, throw no light on the problems of Dan and Nikolai creeks. The three faults just mentioned are the most prominent ones of the Nizina district, but they are not the only ones. There is evidence in many places of movement of the greenstone and limestone formations along their plane of contact, but measurements of displacement under such conditions are difficult. Undoubtedly faults are present in many places where they have not been recognized, for it is only under favorable conditions that they are discovered. Such condi- tions are provided by the limestone-greenstone contact. The char- acter and frequency of faulting are shown on the geologic map by the contact north of Dan Creek. Displacements of the kind occurring there are difficult to recognize and to trace where only one of the formations is present. Most of the observed minor faults make obtuse angles approaching 90° with the major strike faults and are vertical or nearly so. They are present in many places and are commonly of small displacement in comparison with the strike faults even when of considerable horizontal extension. The shear zone of the Bonanza ore body is of this class. It was traced in a direction N. 30° E. from the mine for a distance of 1 mile, but the displacement at the limestone-greenstone contact is only 2 feet. A parallel fault on the east side of McCarthy Creek has a displacement of over 500 feet. The numerous faults north of Dan Creek are vertical or nearly so and have displacements ranging from 10 or 15 feet to several hundred feet. Minor strike faults were also noted, but since they do not cut bedding or formation boundaries they are apt to be un- discovered, as are also faults of low dip, such as the horizontal frac- 70 THE NIZINA DISTRICT, ALASKA. ture planes of the Bonanza mine, along which slight movement has taken place. In summarizing what has been said about faulting attention is directed to the fact that in a broad way the faults may be divided into two classes, those parallel to the prevailing strike of the forma- tions and those that are approximately perpendicular to it. These may be referred to as strike faults and dip faults, for they are vertical or approximately so, and their strikes correspond in a meas- ure with the direction of strike and dip of the formations. The principal strike faults have given rise to great displacement of the rocks cut by them and persist for long distances horizontally. The dip faults are more numerous but the displacements are smaller. The effects of these faults on the rocks may be compared to the fracturing of the ice in a glacier. Blocks were formed which had to adjust themselves to surrounding conditions; some of them moved up, some down, as will be seen by examining the limestone-greenstone contact north of Dan Creek. In this way adjustments of great amount were brought about by many small, widely distributed displacements. AREAL GEOLOGY. The areal distribution of each formation has been indicated in the description of the formation. It now remains to bring these scat- tered facts together in one brief statement. Fully one-third of the mapped area is occupied by unconsolidated gravels, sands, etc., of glacial and fluvial origin (PL III, in pocket). Two-thirds of the remainder is given to the Kennicott formation. Consequently less than one-fourth remains to the rocks older than the Jurassic. The greenstone, the limestone, and the Triassic shales are confined strictly to a belt along the northeastern side of the area, but their territory is invaded in a few places by outliers of the overlying basal beds of the Kennicott formation. Triassic shales occupy only a small part of the area belonging to the older rocks, for the map does not extend far enough north to include the places of their greatest develop- ment. They are seen along the boundary of the mapped area be- tween McCarthy Creek and Nizina River and in the vicinity of Copper Creek. The Nikolai greenstone and the Chitistone lime- stone form a narrow belt that extends northwest from Pyramid Peak to Kennicott Glacier. Nothing but Kennicott sediments and the igneous rocks intruded in them appears south of the Triassic formations. They appear in two principal areas on the two sides of Nizina River and are separated by a broad stretch of gravel deposits. Quartz diorite porphyries cut the Kennicott sediments in all parts of the district but find their greatest development in the black shales, particularly the shale area north of Nizina River. The per- HISTORICAL GEOLOGY. 71 phyry sills of Copper Creek are conspicuous because of their per- sistence, but the intrusives of Porphyry and Sourdough peaks are so much greater in amount that they dominate in the upper parts of these mountains. It may not be out of place to state here that the four formations of the Nizina region continue northwestward beyond Kennicott Glacier and that their areal relations there are practically the same as on the east side. Black Kennicott shales with numerous porphyry in- trusives make up the mountains west of Porphyry Peak on the opposite side of Kennicott River, and the greenstone and Triassic sedimentary formations appear north of Fourth of July Pass. The mountain in the middle of the glacier, known as “ The Peninsula,” gives an excellent section of the greenstone and the two Triassic for- mations. Greenstone forms the southern point of u The Peninsula.” On it lies the northeastward-dipping limestone, which is succeeded in turn by the Triassic shales. This locality is one of a few in this region where the limestone has been closely folded and much con- torted. It is known regarding the extension of these formations toward the southeast that the greenstone outcrops on Canyon Creek east of Young Creek, and it is probable that both greenstone and limestone extend still farther eastward into the Chitina Valley. Schrader traced the black Jurassic shales, which were at first thought to be Triassic, as far east as Canyon Creek, but beyond that there is no information concerning them. HISTORICAL GEOLOGY. SEDIMENTARY AND IGNEOUS RECORD. In describing the formations of the Nizina district the rocks of sedimentary origin were considered in one group and those of igneous origin in a second. This treatment by family groups is not followed in the discussion of the historical geology of the district, but rather it is attempted to give in the order of their occurrence the geologic events connected with the different rocks. The first event in the geologic history of the district concerning which we have evidence within the district is the outpouring of lavas that are now known as the Nikolai greenstone. This took place pre- vious to the deposition of the Chitistone limestone, and consequently either in Upper Triassic time or in some period preceding it. It is not, probable, however, that the greenstone flows are older than the Triassic, since the best evidence at hand indicates that they are later than Carboniferous. The flows did not take place as a single event but were doubtless continued through a considerable time interval. There is some reason to believe that they may have been 72 THE NIZINA DISTRICT, ALASKA. poured out under water, although it is by no means established that such is the case ; yet, whether they accumulated in the sea or whether they accumulated on land and were later carried below sea level by subsidence of the land, the beginning of deposition of Upper Triassic marked the complete cessation of volcanic activity for the time being. Deposition of the Chitistone limestone continued for a long interval of time without important changes in the character of the material laid down. At first the conditions of accumulation were relatively stable and the massive beds at the base of the Chitistone were formed, but later conditions changed, for the beds grew thinner, and finally thin partings of shale began to appear. The commencement of shale deposition marked the beginning of the transition from the Chitistone limestone to the McCarthy shale. As the shale beds increased in amount the limestone decreased, till finally shale predominated and limestone was no longer of importance in the formation. All these events that concern the sedimentary formations took place before the end of the Triassic period. They terminated with an elevation of the Triassic sediments above sea level, which was accompanied or followed by deformation and folding of all the sedimentary beds and the greenstone. Erosion of the new land surface began as soon as elevation took place and, unless part of the historic record has been lost or overlooked, continued throughout Lower and Middle Jurassic time. During this erosion period an enormous quantity of material was removed from the land and returned to the sea, but what became of it is not known. The beveled edges of the greenstone, the lime- stone, and the shale bear evidence of an areal extension of these formations beyond the limits now recognized and testify to the thou- sands of feet of material carried away. Erosion was at last interrupted by the advance of the Jurassic sea. This advance probably took place from the west, where it began in Lower Jurassic time, as is known from the presence of Lower Jurassic beds on Cook Inlet. Upper Jurassic sea prevailed in the Chitina region long enough to permit many thousand feet of sedi- ments to accumulate. This sea is supposed to have been a somewhat restricted one. The waters were shallow. Probably a land mass existed to the south in the region of the present Chugach Moun- tains and separated the sea from the ocean. The sediments de- posited in the Jurassic sea are not all of one kind and were de- posited under varying conditions. The Kennicott formation bears within itself evidence of many and important changes during the time when it was being laid down. Shore conditions are indicated by the basal conglomerate, but the gradual upward decrease in size of the pebbles that form the conglomerate and the transition from conglomerate or grit to sandstone and from sandstone to fine black shales tell of a progressive change in conditions that is difficult HISTORICAL GEOLOGY. Y3 to interpret, for it may have been caused in various ways. The great thickness of fine black shale, however, is evidence of long- continued stability in the source of supply and the manner of deposition of the materials composing them. Stability at last gave place to instability, and another great thickness of interbedded shales and sandstones followed the black shales till the last known event of Upper Jurassic deposition took place and the massive upper conglomerate was laid down. Deformation, elevation above sea level, and intrusion by quartz diorite porphyry are the next events re- corded in the rocks of the mapped area, and they lead up nearly to the beginning of development of the present topography. Yet there is reason for assuming that the Kennicott formation does not repre- sent the latest rocks of the Nizina district and that other younger sedimentary and igneous rocks may have once been present but are now entirely removed. This assumption is based on the presence of coal-bearing beds and still younger lava flows in the vicinity of Fourth of July Creek, west of Kennicott Glacier, and on the head of Chitistone River. Neither of these localities has been studied in detail. The coal of Fourth of July Creek is confined to a small area. It lies horizontally, is associated with black carbonaceous shale, and is overlain by arkose sandstone and an andesitic lava flow. Its relation to the great fault that cuts the Kennicott and older formations is such as to leave little doubt that it was deposited after faulting took place, and it is provisionally referred to the Tertiary. Coals associated with shales and sandstones and overlain by lava flows are exposed on Chitistone River. These beds also are referred to the Tertiary. The presence of these younger rocks in the immediate vicinity makes it appear highly probable that they may have extended into the region under consideration, since it is diffi- cult to understand how they could have been deposited where they now appear without being much more widespread than they are. A coal-bearing formation consisting predominantly of coarse arkose and showing no evidence of marine conditions, but included between marine Tertiary formations, reaches a thickness of more than 2,000 feet in the Controller Bay region.® More than 3,000 feet of fresh-water coal-bearing Tertiary sedi- ments are exposed in the Matanuska region. * * 6 These sediments comprise “ a series of sandstones, shales, arkose, numerous coal seams, and a large volume of conglomerate.” The Gakona formation of the Copper River basin c is a coal-bearing for- ® Martin, G. C., Geology and mineral resources of the Controller Bay region, Alaska : Bull. U. S. Geol. Survey No. 335, 1908, p. 31. 6 Paige, Sidney, and Knopf, Adolph, Geologic reconnaissance in the Matanuska and Tal- keetna basins, Alaska : Bull. U. S. Geol. Survey No. 327, 1907, p. 27. c Mendenhall, Walter C., Geology of the central Copper River region : Prof. Paper U. S. Geol. Survey No. 41, 1905, p. 52. 74 THE NIZINA DISTRICT, ALASKA. mation of fresh-water origin. It reaches a thickness estimated to be not less .than 2,000 feet and includes 500 feet of conglomerate, together with shale, gravel, sand, and lignite beds. Other areas of supposedly Tertiary sediments appear in the Copper River valley, but very little is known about them. If the coal-bearing rocks occurring just north of the Nizina district are of Tertiary age, it is a reasonable presump- tion in the absence of definite proof that they, like the coal-bearing Tertiary formations of the Matanuska and Copper River basins, are of fresh-water origin, and that therefore there is no necessity for assuming a submergence of the region below sea level after the Ken- nicott formation was deposited. The element of doubt in this pre- sumption lies in the uncertainty concerning the age of the coal, for it is known that the Upper Jurassic formations as well as the Tertiary formations of the Matanuska region carry coal. PHYSIOGRAPHIC RECORD. There is good evidence in many parts of Alaska to show that at the time when the Tertiary coal formations were deposited the land had a much lower relief than it has to-day. The present mountain ranges, although perhaps distinctly outlined, had not yet reached their full development. The coal formations were laid down in depressions of a land surface that must have lacked in large measure the rugged character that we now see. Probably this land surface presented many of the features of the present Copper River or Yukon valleys in their broader parts. Such appear to have been the conditions when the forces that resulted in the uplifting produc- tion of the present Chugach Mountains and the Alaska Range began to be felt. These forces doubtless acted slowly, but they acted for a long period of time, and they may be in operation yet. They brought about the uplift of the mountain areas and made it possible for the agents of erosion to initiate the work of forming the present moun- tain and valley features. They w T ere accompanied by or were the cause of the extrusion of a great volume of lava that has continued almost to the present day and is the most characteristic feature of the Wrangell Mountains, the feature that distinguishes them from the Chugach Mountains on the south and the Alaska Range on the north. Chitina Valley is a very old topographic feature and was formed bv a stream that probably had an outlet by way of the upper Copper River valley either into the drainage basin of Cook Inlet or possibly into the Yukon Valley. Its axis coincides with the boundary line between the older metamorphic rocks of the Chugach Mountains and the younger, less-altered rocks on the north side of the valley. This boundary in part marks an unconformity of deposition and possibly also one of faulting, but in either case it appears to have been a ECONOMIC GEOLOGY. 75 determining factor in locating the position of the valley. The valleys of Nizina River and the other streams of the Nizina district, like the Chitina Valley, originally represented the work of streams alone and were the result of normal stream erosion, but they have been profoundly modified by the action of glacial ice. This modification is represented chiefly by changes in valley forms due to straightening of the sides, alterations in the form of cross section, and lowering of the valley floors, together with changes brought about by the deposi- tion of unconsolidated glacial materials. These modifications having already been described in the section on glaciation, it is unnecessary to repeat their description here. It is only necessary to say that the most conspicuous topographic features we see to-day owe their present appearance to recent glaciation, yet that subsequent stream cutting and rapid subaerial erosion due to the subarctic conditions have begun to modify the land forms left by the retreating ice. These later features are seen in the rock- walled canyons on the lower courses of all the streams, the deep gulches such as cut the Kennicott formation on White and Young creeks, and the great accumulations of loose material in the form of talus. ECONOMIC GEOLOGY. HISTORY. The history of mining in the Chitina Valley begins with the rush of prospectors to Valdez in 1898. These men were influenced by the gold discoveries in the Yukon Basin during the preceding two years and came to Valdez in the hope of finding an easier route to the Yukon or new placers in the Copper River valley. Reports of cop- per on Copper River had circulated since the time of the Russians, who found in the hands of natives copper that probably came from the Nizina district, yet a majority of the prospectors were in search of gold, not copper. A few, however, turned their attention to cop- per and crossed from Valdez to the Wrangell Mountains, where their efforts received encouragement. In the following year (1899) the search for valuable minerals was resumed and prospecting parties ascended Chitina Valley as far as the Nizina district. It is doubtful if they attempted to go farther east in the main valley, and for that matter there has been little effort to prospect the upper Chitina region in the years since then. The Nikolai copper lode was shown to a party of white men by a native sent for this purpose by Chief Nikolai, of Taral, in July, 1899. Nikolai’s house was at the mouth of Dan Creek, and the ore body was doubtless discovered by the natives on some of their hunting expeditions. It is usually difficult to recon- cile the statements of different persons concerning the early events connected with the history of a new country, and the Nizina district is 76 the nizika district, Alaska. no exception to the rule. It is said that gold was discovered on both Dan and Young creeks at about this time, but either the quantity found was small or the difficulties met prevented any immediate steps toward developing the property. Work was begun on the Nikolai mine in 1900 for the purpose of securing a patent to the claim. Some of the men who were interested in the property devoted part of their time to further prospecting, and in this way the large body of chalcocite named the Bonanza ore body was discovered about the end of July or the first of August (1900) by C. L. Warner and Jack Smith. It was discovered independently a short time later by Spencer, of the United States Geological Sur- vey, who was engaged in mapping the contact of the Nikolai green- stone and the Chitistone limestone. Up to this time interest in gold placers had been secondary to that in copper prospects, but the pres- ence of gold on Dan Creek was not forgotten, and in 1901 the creek was staked by C. L. Warner and D. L. Kain for themselves and others. Mr. Kain was known to his companion as “Dan,” and they named the creek after him. The first men to find gold on Chititu Creek were Frank Kernan and Charles Koppus, who came to the creek in the first part of April, 1902. They were joined shortly afterwards by two others, Messrs. Rowland and Dimmet, and these men staked the creek for themselves and their partners on April 25. News of the Nizina strike quickly reached the outside, and by July of 1902 the stampede was under way. A new town sprang up on Chititu Creek and was quickly pro- vided with all the usual elements of a thriving placer camp, but there was not enough placer ground to support all comers, and most of the population soon vanished. The richest and most easily mined gravels were largely worked out in the first years by pick and shovel, but since that time the claims on both Chititu and Dan creeks have become more and more consolidated in the hands of a few owners, who are preparing to handle their gold-bearing gravels on a larger scale by more economical methods. A similar consolidation of ownership has taken place in the case of the Bonanza mine, so that now instead of 11 principal ownerships, some of them representing two or more persons, the property is con- trolled by a single strong corporation capable of supplying the large capital necessary to develop the ore body. The mineral production of the Chitina Valley to the present time consists entirely of gold, which is practically all from Chititu and Dan creeks. Copper has not been produced in a commercial way because there is no means of getting it to the coast, so that all the copper brought out is that taken for samples and assays. ECONOMIC GEOLOGY. 77 COPPER. OCCURRENCE OF THE ORES. GENERAL STATEMENT. An examination of the copper prospects of the Chitina Valley was made by members of the United States Geological Survey in 1907, and a report of that work was published in bulletin form later.® Since that time there has been considerable advancement in the development of some properties and a few discoveries have been made, yet the results of the work done have thrown no light on the nature of the changes which take place in the ore bodies as distance from the surface increases. This question, excepting that of the amount of ore present, is probably the most important one con- cerning the copper deposits of the region. A study of the copper deposits on the eastern side of the Wrangell Mountains * * & has shown that copper occurs there under much the same conditions as in the Chitina Valley and has suggested some further ideas as to the origin of the ores. The descriptions and discussion that follow, then, are based partly on previous work but have received such revision and addition as have been found to be necessary. Copper ores in the Chitina Valley north of the river occur in three ways — as copper and copper-iron sulphides associated with the Nikolai greenstone and with the Chitistone limestone; as native copper associated with the greenstone ; as placer copper accompanied by native silver and gold. The important copper minerals are chal- cocite or copper glance, bornite, chalcopyrite, and native copper. In every copper prospect there is a small quantity of one or more of the oxidation products, such as green malachite stain, azurite, and less frequently the red oxide, cuprite. Chalcanthite, or blue copper sul- phate, and the black oxide, tenorite, are rare. Covellite is associated with chalcocite in some localities. The ore bodies occur as replacements of greenstone or of limestone or as fillings in cavities developed along fault planes, shear zones, or joint planes in greenstone or limestone. A few examples are known of ore bodies to which the term “ fissure vein ” might be applied in its popular sense, but by far the greater number of the copper de- posits are aggregates of copper minerals forming ore bodies of irregular shape which are well described by the term “bunch de- posits,” yet even the “ bunch deposits ” are believed to owe their existence to the presence of faults or fractures that permitted the circulation of copper-bearing solutions. Aggregates of copper min- " Moffit, Fred H., and Maddren, A. G., Mineral resources of the Kotsina-Chitina region, Alaska : Bull. TJ. S. Geol. Survey No. 374, 1909. 6 Moffit, Fred H., and Knopf, Adolph, Mineral resources of the Nabesna- White district, Alaska : Bull. U. S. Geol. Survey No. 417, 1910. 78 THE NIZINA DISTRICT, ALASKA. erals are far more common in the greenstone than in the limestone, but the largest deposits that have been discovered up to the present are in limestone. Most of the deposits in limestone are nea"r the base of the Chitistone formation, yet there are a few notable exceptions to this general rule. On the other hand, the attempt to show that deposits in the greenstone are most apt to occur near or at the lime- stone-greenstone contact was not successful, and the field evidence seems to indicate that copper occurs in nearly all parts of the forma- tion and that the location of ore bodies is dependent only on favor- able conditions of supply or for deposition. COPPER SULPHIDE DEPOSITS IN GREENSTONE AND LIMESTONE. Although this part of this paper is intended to deal only with the copper prospects of the Nizina district, it is necessary in the descrip- tion of the ores to consider the district in its relation to the rest of the Chitina region. The best examples of copper sulphides in green- stone are not found within the region under consideration but to the west of it. The copper minerals are bornite, chalcopyrite, and chalcocite, with secondary alteration products, and they occur (1) in irregularly shaped ore bodies without any conspicuous amount of associated gangue minerals or (2) as well-defined veins accom- panied by a gangue of calcite and quartz. Ore bodies of the first kind occur in shear zones or in jointed or shattered portions of the rock. The copper minerals fill fractures in the rock, or more com- monly they replace the rock itself. Bornite and chalcopyrite are of more common occurrence than chalcocite, yet some of the most prom- ising ore bodies in the greenstone consist chiefly of chalcocite. A careful examination of the many copper prospects leads to the belief that most of the ore bodies are of the “ bunch deposit ” type and are a replacement of the greenstone by copper minerals carried in solutions that circulated along fracture planes produced by joint- ing, shearing, or faulting of the country rock. The mineralized parts of the greenstone are without definite boundaries in many places, and the ore grades from solid sulphides to disseminated grains or particles scattered through the greenstone, which grow fewer and fewer as distance from the fractures increases till they disappear altogether. Sections of ore examined under the microscope show that the two sulphides bornite and chalcopyrite are closely associated and are intermingled in such a way as to suggest that they were deposited at the same time. Chalcopyrite is practically always pres- ent, even in ore that appears to the naked eye as pure bornite. Chal- cocite accompanies the bornite and chalcopyrite in some specimens, and the association is such as to suggest that the chalcocite was derived from the poorer sulphides, but this was not definitely proved. A few of the deposits in greenstone consist entirely of chalcocite. COPPER. 79 The vein deposits accompanied by gangue minerals are associated with well-defined faults in all the best examples. The copper min- erals are bornite and chalcopyrite, and the gangue is chiefly calcite accompanied by quartz. Epidote is commonly present also. The veins pinch and swell markedly in short distances and in all the localities where they were examined have been subjected to faulting or other movement, since their deposition. Copper deposits in limestone were formed by replacement of the limestone as a whole by copper minerals in solutions circulating along fracture planes such as faults, shear zones, or joints. The cop- per minerals are chalcocite and bornite, accompanied by malachite, azurite, and in places covellite as alteration products. As a rule, the boundary between ore and country rock is distinct, although the form of the ore body itself may be very irregular. This is particu- larly true where the copper mineral is chalcocite. In deposits of bornite in limestone a dissemination of the copper mineral through the adjacent country rock was noticed, and in such examples there is a gradation from ore to country rock similar to that in the green- stone deposits. One of the best examples of this kind shows a large proportion of chalcocite associated with the bornite, and the deposi- tion of the copper was accompanied by a thorough silicification of the limestone. Large masses of chalcocite like that of the Bonanza property are distinctly replacement deposits in fracture zones. No fragments of limestone are included in the body of the ore, although isolated masses of chalcocite are scattered through the limestone. The ores are most frequent near the limestone-greenstone contact, yet some of them must be fully 1,000 feet above the base of the lime- stone. It is a notable fact that azurite is far more common as a secondary oxidation product in the limestone replacement deposits than malachite and that it is not common in the deposits in green- stone. Small veins of azurite with cores of chalcocite show distinctly that the azurite in the Bonanza mine was produced by the alteration of chalcocite. Covellite originated in a similar manner. NATIVE COPPER ASSOCIATED WITH THE GREENSTONE. Native copper is associated with amvgdaloidal phases of the Nikolai greenstone and is also found accompanied by quartz or by quartz and epidote in veins cutting the greenstone. Most commonly it occurs as grains and small slugs in the amygdules and disseminated through the greenstone and as films or leaves and small veinlets cutting the greenstone. Tabular masses deposited in joint planes without much doubt indicate the way in which the large masses of native copper and. the copper nuggets in the Dan and Chititu placers were formed. Such masses found in place on the head of White River are believed to have resulted from the alteration of chalcocite. In a few places 80 THE NIZINA DISTRICT, ALASKA. in the tributary valleys of the Chitistone and Kotsina rivers native copper occurs in amygdaloidal greenstone in association with a mix- ture of copper oxide and carbonaceous matter, filling vesicles and fractures in the lavas. Such native copper as is known in the Nizina district is probably due to the reduction of previously formed sul- phides or oxides, yet primary native copper is known on the head of White River. There is a strong similarity between the native copper- bearing greenstone of Chitina Valley and the amygdaloidal copper ores of Lake Superior. Specimens from the two regions could be selected between which it is doubtful if close observation could distin- guish. This similarity would also extend to the disseminated sul- phide ores in greenstone if by any means the sulphides could be altered to native copper. PLACER COPPER. Native copper is associated with silver and gold in the gravels of Chititu and Dan creeks. It occurs in pieces that range in size from fine shot to masses weighing several hundred pounds. Two or three tubs of fine copper are secured at each “ clean-up ” of the sluice boxes on Chititu Creek and give much difficulty in cleaning the gold, since the finest of the copper has to be removed by hand. Many of the nuggets contain native silver, which shows that the copper and silver are here closely associated in origin. The remarkable similarity in form and appearance between the copper nuggets of the Nizina dis- trict and the larger masses of copper taken from the stamp mills of the Lake Superior region is evident to anyone who compares the two, since the chief differences are that the placer copper has a slightly smoother surface and an oxidized coating. The copper and silver are derived wholly or in part from the greenstone. Assays of clial- cocite from the Bonanza mine and from other copper ores of the Nizina district have shown the presence of both silver and gold in the copper deposits. Small particles of native silver were found in a freshly broken specimen of greenstone from a bowlder on Chititu Creek, and an assay of the rock also showed its presence. The silver was associated with calcite in small fractures. Silver nuggets up to 7 pounds in weight have been found on Dan and Chititu creeks, but where silver is associated with copper in the same nugget copper predominates, and in general silver is seen only as small particles in the copper. Copper is found only in those tributaries of Dan and Chititu creeks" where greenstone pebbles and bowlders form part of the stream gravels: consequently it occurs only where the gravels have been formed in part b}^ streams flowing through greenstone areas or where there is a foreign element in the gravels that was derived from a greenstone area and brought to its present position by glacial ice. COPPER. 81 * ORIGIN OF THE COPPER DEPOSITS. It is not yet possible to give a satisfactory account of the origin of the copper deposits, but some features of their history can be stated with a considerable degree of certainty, and it is desirable to do this, since it may be of value in future development work. A history of the present deposits is concerned chiefly with three prob- lems — the source of the copper minerals, the manner in which they were brought to their present position and deposited, and the changes that have taken place in them since they were deposited. It is believed that the source of the copper is within the Nikolai greenstone itself and that only a very small part, if any, is derived from an outside source. The chief argument in favor of this view is the widespread and almost universal occurrence of copper miner- als in the greenstone wherever it is exposed. This is seen in hun- dreds of places in all parts of the formation, from the west end of the Chitina Valley to Nizina River and the upper Chitina. Wherever fractures in the greenstone have permitted water to circulate the green copper stain is apt to be found. Probably the copper was originally present in the form of sulphide in the lava flows, but this does not exclude the possibility of its also having been combined in other minerals of the rock. Pyrite and chalcopyrite are of com- mon occurrence in the greenstone, as is proved by both the hand specimens and the thin sections examined under the microscope. This source is believed to be adequate for supplying all the copper concentrated in the present ore bodies. An examination of the greenstone in many places has shown that considerable chemical alteration in its constituent minerals is uni- versal. No fresh and unaltered specimens of the rock were found. Alteration began first and is greatest in the pyroxene, and in ma no- places this alteration is complete, so that there now remains only a mass of chloritic or serpentinous material. The feldspar has suf- fered less, yet the changes are advanced. Opaque masses of brown iron oxide appear to represent original grains or crystals of pyrite or chalcopyrite. These changes have resulted in the production of chloritic and possibly serpentinous material, calcite, quartz, and delessite. In places zeolites as thomsonite have been produced, but they are comparatively rare in the Nizina district and the region to the west, although they are abundant in amygdaloids of the White River region. Changes of the kind mentioned • are usually considered to be accomplished through the agency of circulating water. Chemical changes in the minerals of the basalts were made possible by the presence of water and the substances carried in solution. Ry the same means copper minerals were taken into solution and redeposited 7064S°— Bull. 443—11 G 82 THE NIZINA DISTRICT, ALASKA. under favorable conditions. It is a noteworthy fact that the Wran- gell Mountain region has been one of volcanic activity since Car- boniferous time at least, and, although it has not been possible to establish a direct relation between the copper deposits and any igneous rocks of later age than the Nikolai greenstone, it is not unreasonable to suppose that the presence of heated rocks in the near vicinity may have had an important influence in promoting circula- tion in the greenstone and particularly in increasing the solvent power of the circulating water. As to the manner of deposition, it is believed that the copper taken into solution by circulating water was carried into trunk channels and deposited there when the conditions were favorable. Specula- tions as to the exact chemical changes that took place are of very doubtful value with the present knowledge of the facts and will not be attempted. Most frequently deposition took place in the green- stone formation, but at times the copper-bearing waters passed out- side the greenstone and into the overlying limestone before giving up their mineral load. As a rule, the ore bodies were not formed by the deposition of copper minerals in open cavities, although openings sufficient to permit a circulation of water were necessarily present. Most of the ore is a replacement of the country rock itself by copper sulphides. The replacement of greenstone is more nearly complete adjacent to the openings through which water passed and grows less and less as the distance from the openings increases. On the other hand, most of the limestone ores show a complete replacement of the limestone without any outside zone of disseminated sulphides. Examination with the microscope has shown that bornite and chalcopyrite are usually associated in the greenstone deposits, even in bornite ores that show no chalcopyrite to the unaided eye. This fact, together with the manner in which chalcopyrite is scattered through the bornite, might be taken as presumptive evidence that the bornite was derived from chalcopyrite and is a secondary enrich- ment. This fact alone does not amount to proof, but the seeming increase in chalcopyrite as depth is gained in some of the bornite- chalcopyrite veins, such as the Nikolai vein, lends some weight to the presumption. The presence of native copper associated with chalco- cite and bornite also points to the same conclusion, since native copper is usually regarded as of secondary origin. On the other hand, no evidence was found in the chalcocite deposits in limestone, such as that of the Bonanza mine, to indicate that the ore body has ever been anything other than what it is at present. The copper sulphide appears to have been deposited as such, and a careful examination of the ore has failed to discover the presence of other minerals than those produced by alteration of the chalcocite. It is doubtful if sec- ondary enriched ores could form under the conditions now prevailing COPPER. 83 at the Bonanza mine, since all openings such as are due to joints and other fractures are filled with ice, as is also the loose talus material below the mine on both sides of the ridge. Furthermore, the break- ing down of the ore and of the limestone inclosing the ore body under the climatic conditions of this region proceeds faster than oxidation. The exposed ore on the ridge and loose broken-down ore on the talus slopes show only a thin film of oxidized material on the surface. Yet thin veins of chalcocite in the limestone and even large masses of chalcocite have been almost completely altered to azurite, which shows that oxidation has taken place either under present conditions or, more probably, under earlier and more favor- able conditions, possibly before the late ice advance. The ore of the Westover claim, on Dan Creek, is an intimate mixture of chalcocite and bomite in silicified limestone along a frac- ture zone. The copper and copper-iron sulphides are disseminated through the rock in small grains and in veinlets cutting the rock. Most of the disseminated grains are chalcocite, but the veinlets and the larger irregular masses are a mixture of chalcocite and bornite. The veinlets are later than the quartz inclosing them and pos- sibly later than the disseminated grains in the quartz, yet the minerals of the veinlets appear to be contemporaneous. These examples show how unsatisfactory is the evidence concerning the nature of the deposits, but they have some importance in that they do not promise greater richness in copper as the ores are followed below the surface. This point is emphasized because of the belief on the part of many prospectors in the Chitina region that the de- posits will grow richer as they are more fully developed. The con- trary is more likely to be true, for although they may continue with their present richness they are more apt to grow poorer than to grow richer. DESCRIPTION OF PROPERTIES. PRINCIPAL GROUPS. The better-known copper properties of the Nizina district may be divided into three groups — first, the group in the vicinity of Bonanza Peak, including the Bonanza mine, the Jumbo, the Erie, and the Independence claims, together with the properties known as the Mar- vellous and Bonanza extension claims; second, the Nikolai Creek group; and, third, the group that includes the Westover claim and other neighboring claims north of Dan Creek. Many other claims have been staked, particularly along the limestone-greenstone contact, but there has been little development work done on them and they con- tribute little to our knowledge of the copper deposits of the district. 84 THE NIZINA DISTRICT, ALASKA. BONANZA MINE. The Bonanza mine is the most valuable® copper property now known in the Copper River region. It is situated on the east side of Kennicott Glacier, at the head of Bonanza Creek, and is the property of the Kennicott Mines Company. Bonanza Creek proper and its western fork head in a glacial cirque basin on the west side of the high divide between Kennicott Glacier and McCarthy Creek. Its two forks include the high ridge on which the copper deposit is situated. The stream is about 3 miles long and flows in a south- westerly direction to the Kennicott Glacier. A post-office called Kennicott has been established at the mouth of National Creek, half a mile south of the mouth of Bonanza Creek and 4 miles from the mine, and the company’s main camp and office are located at that place. A wagon road leads from the mouth of National Creek to a point about 500 feet below the mine and another follows the edge of the glacier south to McCarthy Creek. An aerial tram with a capacity of 100 tons per day has been constructed and loading and delivery stations have been built, so that the mine is now practically ready to begin the production of ore, although the storage bunkers are not completed and no ore can be shipped till the railroad reaches Kennicott. An examination of the geologic map (PI. Ill, in pocket) will make clear the general geologic conditions. South of National Creek the high ridge between the glacier and McCarthy Creek consists of black Kennicott shale intruded by large masses of light-grav por- phyry. The Jurassic shales and intrusives are separated b} T an un- conformity and probably also by a fault from the greenstone and the overlying Chitistone limestone on the north. North of National Creek the greenstone and limestone appear. The strike of the lime- stone is northwest and southeast, and its dip averages between 25° and 35° NE. It therefore cuts diagonally across the main ridge from McCarthy Creek to the glacier. Still farther northeast the Triassic shales overlying the limestone appear, but are not of any importance in connection with the copper. The Bonanza mine is situated on a spur that runs out to the south- west between the forks of Bonanza Creek from the main ridge. This spur is crossed by the limestone-greenstone contact at a point about one-third of a mile from the main ridge. Where the boundary crosses the crest of this spur it has an elevation of G,000 feet above sea level or 4,000 feet above the point at the mouth of National Creek where the tramway will deliver ore. On the northeast the spur ° Since the Bonanza mine was visited in 1907 much work has been done toward surface development and equipment of the mine for shipping ore, but work on the ore body itself has not been such as to add greatly to the knowledge of the deposit. For this reason the description here given is based largely on the previous description published in Bull. U, S. Geol. Survey No. 374, BULLETIN 448 PLATE XII WEST SIDE OF RIDGE AT BONANZA MINE. The richest ore exposed on the surface is on the top and face of the ridge between the points indicated by arrows. See page 85. COPPER. 85 rises rapidly till 1,000 feet in elevation is gained, but on the south- west its crest is almost horizontal for a distance of about one-third of a mile, beyond which it slopes away steeply to the forks of Bo- nanza Creek (PI. XII). The greenstone immediately below the ore body is variable in texture and general appearance. Part of it is amygdaloidal ; por- phyritic phases are also present. Amygdules are not confined to the top of the flows but are present throughout from bottom to top. In some places they have been dissolved out on exposed surfaces, leaving a vesicular rock that looks like a recent lava. A bed of red and green shale having a thickness of about 5 feet intervenes between the green- stone and the overlying limestone. This shale forms a narrow north- ward-sloping bench for a short distance along the northwest side of the ridge, but is everywhere covered with talus and is found only when the debris has been cleared away. The bench is clearly indi- cated by the snow banks in Plate XII. The base of the lime- stone consists of not less than 40 feet of coarse gray, slightly argil- laceous rock, whose broken surfaces are covered in many places with flattened cylindrical bodies that immediately suggest organic material of some kind. Several specimens of these bodies were submitted to Dr. T. W. Stanton, who says that they are probably corals but are too obscure for identification. Over this basal limestone is a bed a few feet thick of impure shaly limestone, and this in turn is over- lain by dark and light-gray massive beds which carry the ore bodies. The limestone dip at the mine is slightly variable but averages about 22° NE. The limestone is broken by numerous faults and fracture planes, the most prominent of which are nearly perpendicular and range in strike from N. 40° E. to N. 70° E. A minor set of fault planes with about the same strike dips steeply to the west. Another set runs in a northwesterly direction, and in several places striations on slicken- sided surfaces or clay seams show that the movement was horizontal. Fault planes with low dips, some of them nearly horizontal, are also present. None of the faults observed give evidence of much displace- ment, but together with the numerous joints they afforded an oppor- tunity for mineral-bearing waters to enter the limestone. The prin- cipal fault planes — those running from northeast to southwest — form what may be described as a sheeted zone in the limestone that was traced north-northeast from the Bonanza mine for 1^ miles. This zone has a width of 50 or 60 feet and extends through the shale bed into the greenstone below, but is less noticeable in the greenstone than in the limestone. A vertical displacement of 2 feet occurs in the limestone-greenstone contact along one of the fault planes in the shear zone and is the maximum displacement observed. 86 THE NIZINA DISTKICT, ALASKA. The copper ore is chalcocite. Considerable, azurite has been formed by oxidation of the chalcocite, and covellite is reported also. Covel- lite was not found in the specimens of ore collected from the Bonanza mine by the writers, but good specimens of covellite were collected from the Marvellous claim half a mile to the northeast, and its occur- rence at the Bonanza is not questioned. The chalcocite is in veins or tabular masses of solid ore up to 5 or 6 feet in thickness, in large irregularly shaped bodies, and in stockworks in the brecciated lime- stone. Two principal veins of chalcocite are seen on the surface. They stand almost perpendicularly, 12 to 15 feet apart, and strike N. 41° E., forming the comb of the sharp ridge but crossing it at a slight angle, as the ridge at this place has a more nearly north-south direction than the veins. On the surface the veins do not extend down into the lower impure part of the limestone but end abruptly on reaching it. In places the precipitous northwest face of the ridge is plastered over with masses of solid chalcocite for a distance of 50 or 60 feet vertically below the top. Azurite appears on the surface of the chalcocite and also as a lining of small vugs in the chalcocite, but it is present chiefly as thin veins, that form a network in the limestone and are doubtless due to the alteration of original chalcocite veins, for some of the azurite has an inner core of chalcocite. Azurite is more conspicuous than chalcocite in the surface network of veins in the northern 150 feet of the ore body, but chalcocite forms the great mass of the remainder. The ore bodies formed along the northeast-southwest faults of the northern part of the deposit are not the direct continuation of the large chalco- cite veins at the south, but lie in nearly parallel veins which cut the ridge at a greater angle, their strike being about N. 60° to 70° E. The very rich ore can be traced on the surface for a distance of about 250 feet. It ends abruptly on the south in a nearly vertical limestone wall, but on the north gives place to the lower-grade ores, consisting of small veins of azurite and chalcocite with scattered masses of chalcocite, some of them weighing several tons. This lower-grade ore shows on the surface for a distance of at least 150 feet northeast from the high-grade ores, and small scattered azurite veins extend still farther in that direction. The ore, as it shows on the surface, there- fore, extends northeast and southwest along the strike for a distance of 400 feet. The thickness, however, is more indefinite, but the very rich ore, with its included limestone, as seen at the surface, has a width of approximately 25 feet, although the thickness of ore sufficiently rich to be mined may be greater. A little chalcocite and less bornite are found in some of the shearing planes in the greenstone, but they do not extend far into the green- stone. The quantity is small and inconspicuous and might readily pass unobserved. A small amount of epidote is associated with it in COPPER. 87 places. The main shear zone in the greenstone cuts an older set of quartz-epidote veins whose direction is about north-northwest. These veins do not intersect the limestone. They reach a maximum thick- Figure 5. — Sketch map of the area near the Bonanza mine, showing the limestone- greenstone contact, the location of the richer ores on the surface, and the tunnels. ness of 1 foot and carry small amounts of chalcocite, bornite, and native copper. When the Bonanza mine was visited in 1907 two crosscuts (fig. 5) had been driven in the ore body in a direction N. 33° W. They are 88 THE NIZINA DISTRICT. ALASKA. therefore not exactly perpendicular to it. The longer tunnel starts on the east side of the ridge and 75 feet below its top ; it is 180 feet in length and extends through to the west side of the ridge. The richest ore, consisting of large masses of chalcocite with some included lime- . stone, is encountered at a distance of 90 feet from the tunnel’s mouth and continues for a distance of 21^ feet as measured in the roof. There are smaller bodies of chalcocite, however, for a distance of 10 or 15 feet on either side of the main ore body. About 115 feet from the entrance to the tunnel a winze 83 feet deep was sunk in the ore, and from the bottom a drift zigzags northward approximately 110 feet. In 1909 a new tunnel had been driven below this longer tunnel from the southeast side of the ridge and connected by a raise wdth the winze. The new t.unnel is 78 feet below the upper one and parallel with it. Tn July, 1909, it had been driven 45 feet beyond Figure 6. — Sketch showing form of ore body exposed in the upper northern tunnel at the Bonanza mine. the raise but had not encountered any ore bodies as large as those of the upper tunnels. Several small lenses of chalcocite, the largest about 18 inches thick, were exposed in the tunnel itself, but the raise showed much more, for it cut the large body in which the winze was sunk. The absence of the large chalcocite bodies in the lower tunnel adds some weight to the opinion expressed after the visit of 1907 that the ore would probably not extend into the basal impure limestone beds. About 120 feet southwest of this tunnel is a parallel tunnel driven from the west side of the ridge and 50 feet lower than the little saddle above it on the north. This tunnel starts in a face of solid chalco- cite and extends S. 33° E. for 50 feet. The ore, which is chalcocite with a small amount of azurite, is exposed for 34 feet along the tun- nel, but is interrupted by horses of limestone. The remainder of the tunnel shows limestone cut by small azurite veins and in places containing a small amount of chalcocite. COPPER. 89 A better conception of the form of the ore bodies can be obtained by an examination of figures 5, 6, and 7 than can be given in a written description. The two main parallel surface veins afford only an imperfect idea of the deposit. Those two veins represent a total replacement of limestone along minor zones, where shearing was most intense. The two tunnels show that not only is the lime- stone replaced along the main shear zone but that mineralized waters followed minor fracture planes also, and thus yielded the low-lying ore bodies and great irregular masses seen underground. Between and around the large masses of clialcocite the limestone was shattered and filled with many small veins of ore, which formed a stockwork that is most noticeable in the winze tunnel and on the surface north- east of the main ore body. As a rule, the brittle chalcocite is very little fractured. The limestone, on the other hand, is greatly shat- tered and is filled with thin veins of calcite which are older than SW. wall NW. NE. wall 0 ^ 5 10 15 20 feet Figure 7. — Sketch showing form of ore body exposed in the southern tunnel at the Bonanza mine. the ore deposition. Open cavities in the fractured limestone have been filled with ice, and both the country rock and the talus on either side of this ridge, except for a few feet at the surface, are frozen all summel*. The talus slopes below the ore body contain a large quantity of chalcocite resulting from weathering of the veins above and are a valuable source of copper. It is a suggestive fact that, although the main shear zone of the Bonanza mine extends from the limestone through the thin shale bed into the greenstone below, the large chalcocite bodies, so far as can be determined on the surface, end abruptly at the top of the im- pure shaly beds forming the lower 50 or 60 feet of the limestone. Copper minerals are associated with the shear zone in the greenstone, but only in small amount. Apparently the impure thin-bedded part of the limestone was a less favorable place for deposition than the purer massive beds above. This fact has a practical bearing on the quantity of ore present, for it is evident that if the same condition 90 THE NIZINA DISTRICT, ALASKA. continues underground it limits the downward extension of chal- cocite in the limestone. The continuation of the ore body to the north- east will probably be limited chiefly by the continuation of favorable conditions for deposition in the shear zone in that direction. The exact conditions wdiich determined the deposition of the Bonanza ore body are not known; possibly it was the presence of a shear zone favorable to circulation; but its occurrence, together with that of the Jumbo and the Erie chalcocite bodies to the northwest, next to be described, indicates that favorable conditions for deposition have been established in more than one place and offer encouragement for seeking other chalcocite bodies at the base of the Chitistone lime- stone. JUMBO CLAIM. From the Bonanza mine the Chitistone limestone continues north- westward in a succession of lofty cliffs as far as Kennicott Glacier. The base of these cliffs is at the greenstone contact and in many places contains veinlets and stringers of azurite or chalcocite. In at least two places the quantity of these two minerals, especially of the chalcocite, is so great as to make the deposits of commercial importance. The ore body of the Jumbo claim is 4, GOO feet northwest of the Bonanza, at the head of Jumbo Creek, and is located in limestone just above the greenstone-limestone contact on a small southwestward projecting spur or angle of the limestone cliff. South of it and nearly 200 feet below is the glacier in which Jumbo Creek heads and which must be crossed to reach the ore body. The Jumbo and Bonanza ore bodies are at practically the same elevation above sea level, approxi- mately 6,000 feet. The limestone at the Jumbo is made up near the base of slightly cherty beds ranging in thickness from 8 to 12 inches. The strike is N. 65° W., the dip 35° N. A tunnel 12 feet loiig was started on the south face of the ridge, 10 feet above the greenstone. The limestone is jointed or cut by minor faults parallel to the bedding and is crossed by veins of calcite from 1 to 2 inches thick. Thin veins of chalcocite and azurite accompany them and fill some of the fractures. Seven feet above the tunnel mouth is the east end of a large chalcocite mass which is well exposed on the axis of the ridge. As indicated on the surface, this body of ore is a mass of solid chalcocite 30 feet long, 6 feet by 4 feet 6 inches at the west end, and tapering to a diameter of 1 foot at the east end. It appears to be a rudely lenticular or possibly a conical body, but has irregularly shaped protuberances, as may be seen at the west end, where the steep west face or slope of the spur gives a cross section of the ore body. (See fig. 8.) A little way east of the Jumbo tunnel is a second tunnel in lime- stone a short distance above the greenstone. The tunnel runs nearly COPPER. 91 north or slightly to the northeast in limestone that strikes N. 65° W. and dips 25° N. In the tunnel, which is 12 feet long, the limestone is crushed and jointed. Small veins of calcite and azurite up to 2J inches in thickness fill joint cracks, especially a set of perpendicular minor faults or slip planes running N. 70° W. No chalcocite is ex- posed in this tunnel, but it is believed that the azurite indicates its former presence. Fifty feet below the tunnel a lenticular vein of chalcocite 3 inches thick at its widest part and 3 feet long was found in the limestone. 0 , , , , 5 10 15 20 feet Figure 8. — Sketch of the ore bodj 7 at the Jumbo claim. ERIE CLAIM. The Erie claim is the property of the Kennicott Mines Company and is situated on a steep mountain slope near the east side of Kenni- cott Glacier, 3f miles north of Kennicott, at the mouth of National Creek. The discovery point is a little more than 1,000 feet above the nearest point of the glacier and is at the limestone-greenstone contact, which here strikes N. 78° W. and dips 38° N. Between the limestone and the greenstone is a bed of greenish shale of variable thickness, but ranging from 12 to 18 inches. There is also a very thin bed of shale not more than 1 inch thick in the limestone 8 inches above the base. There appears to have been movement between the limestone and the greenstone along their plane of contact, and they were further disturbed by small faults cutting across the contact at high angles to the bedding in such a way that at one place a wedge of greenstone projects into the limestone. The larger shale bed contains many nodules of chalcopyrite from one-half inch to 2 inches in diameter, and with the chalcopyrite there is associated more or less 92 THE NIZINA DISTKICT, ALASKA. bornite in the larger nodules. Abundant scales of azurite are scat- tered through the shale. No development work has been done on this claim further than to clear away the debris and make an open cut along the contact so as to expose the copper-bearing shale. INDEPENDENCE CLAIMS. The Independence group of claims, belonging to the Kennicott Mines Company, is on the east side of the divide that separates the head of Bonanza Creek from McCarthy Creek and is from 900 to 1,000 feet lower than the saddle where the limestone-greenstone con- tact crosses the ridge. The copper minerals occur in small veins that contain considerable calcite and belong to a sheeted zone striking N. 38° E., thus crossing the contact almost at right angles. This zone passes from the greenstone into the limestone and has its great- est width (about 50 feet) at the contact. The ore is found in the greenstone only and consists essentially of chalcocite, which fills frac- tures and is disseminated through the greenstone. It is later than the calcite filling of the sheeted zone and gradually disappears with increasing distance from the zone of mineralization. The main shear zone intersects a system of quartz-epidote veins striking N. 78° E. and carrying a small amount of bornite. There is a marked similar- ity between the occurrence of copper sulphides in the greenstone at this locality and at the Bonanza mine, but there is no chalcocite body in the limestone of the Independence claim. MARVELLOUS AND BONANZA EXTENSION CLAIMS. The shear zone in which the Bonanza ore was deposited extends in a direction about N. 30° E. from the Bonanza mine for a distance of more than a mile. It crosses the saddle between Bonanza Creek and the glacier on the north and extends to the high point of the ridge running northeast from Bonanza Peak. It was not traced beyond that point. There is no evidence of displacement, but there is a shear zone of indefinite width made up of innumerable small parallel frac- tures filled with calcite and crossed by minor fault planes. These fault planes are believed to have had an important and perhaps a controlling influence in the deposition of copper. All the Bonanza fault northeast of the Bonanza property is owned by the Mother Lode Copper Mines Company and the Houghton Alaska Exploration Company. The principal exposures of copper minerals are on the Marvellous claim, where a number of short tunnels have been driven. The Marvellous claim is on the north side of the glacier east of Bonanza Peak and is about 2,800 feet above the valley of McCarthy Creek. At the south tunnel of the Marvellous the limestone is cut by numerous closely spaced parallel joint or shear planes, many of which COPPER. 93 are filled with calcite and are conspicuous because they are lighter in color than the surrounding limestone. They strike N. 70° E. and dip 70° to 80° N. The tunnel is 15 feet under cover and exposes a vein of chalcocite from 3 to 6 inches wide striking N. 60° W. About 30 feet north of the tunnel’s mouth and 25 feet lower is a vein of chalco- cite in calcite that reaches a maximum thickness of 9 inches. It strikes N. 60° E. and dips 60° to 65° W. The vein is in a well- defined fault plane and can be traced for nearly 200 feet from the tunnel’s mouth. In places it pinches to a thickness of 1 inch and carries no ore. Fine specimens of covellite in chalcocite were ob- tained from this locality. There is a second parallel vein 12 feet to the north, but it is not so long. The main tunnel of the Marvellous is 300 feet northeast of the south tunnel and runs 100 feet S. 85° W. in dark-gray limestone. The vein is a stockwork of small calcite veins, with chalcocite and azurite in crushed limestone. About 20 feet from the face is a crosscut 9 feet long where there is a vertical fissure in the limestone striking N. 25° E. The fissure is filled with calcite and carries chalcocite and azurite. It has a thickness of 6 inches. The limestone is much discolored by iron oxide. Above the tunnel is a large mass of azurite formed by the oxidation of chalcocite whose downward extension the tunnel was expected tp strike. A third tunnel, called the north tunnel, was started on the Mar- vellous claim 200 feet northeast of the main tunnel and 100 feet above it. The copper minerals at this exposure occur along bedding planes of the limestone, which here strikes N. 40° W. and dips 35° E., and along fault planes that cross the bedding. The faults strike N. 10° W. and dip 44° E. NIKOLAI CLAIM. The Nikolai claim is located near the head of Nikolai Creek, 3f miles northeast of the junction of Nikolai and McCarthy creeks and 2,150 feet above it. The exposed ore body is situated near the top of the greenstone formation, about 150 feet below the base of the limestone, and is associated with a fault which cuts the limestone- greenstone contact at this place. It is composed mainly of chalcopy- rite and bornite stained with oxidation products. An examination of figure 9 will show the relation of the ore body to the associated formations. It will be seen that the limestone and greenstone beds, which here strike N. 60° W. and dip 30° NE., are cut by a fault running N. 50° E. and dipping vertically or high southeast. This fault makes an offset of 300 feet in the limestone- greenstone contact and has produced a vertical displacement of the beds amounting to 150 feet. The course that it follows in the lime- stone or in the greenstone at a distance from the contact is difficult THE NIZINA DISTRICT, ALASKA. 94 to trace, but the position of Nikolai Creek east of the Nikolai mine was probably determined partly by the fault, as was also the de- pression between the small knob on the south side of the Nikolai ore body and the hill slope still farther south. Open spaces between the limestone and the greenstone along the fault plane were filled with masses of coarse white calcite. This filling, however, was not seen where both walls of the fault are limestone or greenstone. The main Nikolai vein makes a slight angle with the principal fault and lies to the north of it. It strikes N. 55° E. and dips 70° SE. The ore body was produced by deposition and replacement in a shear zone in the greenstone that has a width ranging on the sur- 1000 500 0 L-j... t— i- j I i 1000 2000 FEET LEGEND Kennicott formation Chitistone limestone + -t- + + +■ " + + + Nikolai greenstone Main fault Copper lode Shaft Figure 9. — Sketch map of area in vicinity of Nikolai mine. face from 4 to 6 feet. Deposition of copper minerals was confined to a part of the shear zone that has a horizontal extent from north- east to southwest of 150 feet, but the shear zone itself can be traced 100 feet farther southwest and 350 feet farther northeast, making a total exposure of GOO feet. Several open cuts were made on the vein and a shaft was sunk in the ore body near its northern end a few feet above the creek. Fifty feet south of the shaft two open cuts expose a second fault zone parallel to the first, along which copper minerals were deposited. It was traced for a distance of 50 feet on the surface. Moss and loose rock hide it beyond these limits, but it evidently is much more poorly developed than the fault zone to the north. COPPER. 95 Another set of fractures or joints, with strike N. 15° W. and dip 70° W., is associated with the northeast-southwest faulting but does not appear to have resulted in any important displacement or to have offered favorable channels for circulating mineral solutions, although the openings near the main vein were followed. Still other fractures are present which were not recognized as belonging to any definite system. The copper minerals that form the Nikolai ore body occur parti} 7 as a filling in preexisting cavities and partly as a replacement of greenstone near the cavities. The principal copper mineral is chal- copyrite, but with the chalcopyrite is associated considerable bornite. Where the copper minerals were deposited in cavities they are asso- ciated with other minerals — calcite, epidote, and quartz; where they replace greenstone the other minerals, if they can be distinguished at all, are less in evidence. Deposition was greatest within the sheared and broken rocks of the fault zone, doubtless because the opportunity for circulation was best there. The greenstone walls, within a foot or so of the fault, are sheeted with innumerable tiny parallel fractures now filled with chalcopyrite, giving the rock a banded appearance. Deposition, however, was not confined to these veinlets. It took place also by replacement of the rock itself, so that the greenstone between the veinlets is impregnated with copper sulphide. Small veins from one-fourth to one-half an inch thick show a banding of minerals in places and give a clue to the order in which the minerals were depos- ited. The greenstone walls are covered by a multitude of small epidote crystals, with occasional crystals of quartz, and after them calcite was deposited. Grains and small lumps of chalcopyrite are scattered through both calcite and epidote. The ore taken from the shaft consists largely of chalcopyrite, and the dump shows that there is considerable calcite and quartz associated with it. Bornite de- creases — a fact that is taken as evidence that this mineral belongs to the upper enriched part of the vein and that the ore will be found to consist of chalcopyrite as depth is gained. There has been some movement along the fault since the ore was deposited, but it prob- ably has not produced much displacement. WESTOVER CLAIM. The Westover claim, which is owned by the Alaska United Ex- ploration Company, is on the east side of Bowlder Creek, a little less than 2 miles north of the junction of Bowlder and Dan creeks. The discovery outcrop is a mass of bornite 3,500 feet above the flats of Nizina River and about 375 feet above the glacier moraine of Bowlder Creek valley. It is situated at the contact of the Chitistone 96 THE NIZINA DISTRICT, ALASKA. limestone and the Nikolai greenstone, but the ore body is, so far as now exposed, in the limestone. Most of the limestone-greenstone contact in the upper end of Bowlder Creek valley is covered by talus from the high limestone cliffs that form the valley walls, yet in a few places, of which this locality is one, the contact is exposed for short distances. The strike of the limestone beds and the greenstone flows is here N. 15° W. and the dip is 15° E. In half a dozen or more places within the valley appear small faults cutting across the con- tact of the two formations and causing displacements that in several instances amount to a hundred feet or more. One or two such dis- placements took place a short distance south of the Westover ore body, thus bringing the greenstone at the outcrop to a higher posi- tion with, reference to its nearest exposures on the south than it would have otherwise had. Both limestone and greenstone near the ore body are broken by many joints and crossed by slip planes of little displacement. Locally the rocks are much shattered and break down in small fragments. One of the most prominent of the frac- tures has an important relation to the ore body. It is a fault, probably of small displacement, whose contact surfaces are warped surfaces rather than planes, so that the trace of the fault on the ledge is a curved line sloping from right to left as one looks at it. This fault strikes west-northwest and dips 45° NNE. The ore body lies on the north or upper side of the fault, but is not fully exposed because the talus has been but partly cleared away from its base and the actual contact of limestone and greenstone is not in sight. Copper ore is exposed along the face of the limestone cliff at the top of the talus slope for a distance of 35 feet horizontally and at the south end of the ore body for a distance of about 10 feet vertically. The south end of the ore body is rich massive bornite and clialcocite ore, which is sharply cut off from the limestone south of it by the fault and has been formed by an almost complete replacement of limestone by the copper sulphides. On following the ore body north the richness of the ore rapidly decreases, till finally bornite disappears and only silicified limestone is seen. The copper-bearing solutions followed all the available openings in the limestone — joints, bedding planes, and faults — and the richest ore is near such openings, for here the lime carbonate was wholly replaced by copper sulphides. The amount of replacement varies inversely as the distance from these openings till, within a few inches or a foot, the grains and tiny veinlets of bornite can no longer be seen in the limestone. Where the limestone was greatly shattered the opportunity for replacement was greater ; but in the more massive parts of the beds it took place sparingly, if at all. The sharply defined contact of ore and limestone at the fault on the south suggests that the displacement is later than the ore deposi- COPPER. 97 tion. If this is the case, the present exposure does not show a com- plete section of the original ore body and further prospecting may reveal the displaced part. OTHER PROSPECTS. Tliere has probably been more prospecting for copper in the Nizina district than in any other part of Chitina Valley except the vicinity of Kotsina River. Prospecting was stimulated by the discovery of such deposits as the Bonanza, the Jumbo, the Nikolai, and other claims and by the presence of a greater number of prospectors. The limestone-greenstone contact has been examined with care wherever it is accessible, and most of it has been staked. Most of the copper found is of the class of disseminated sulphides in greenstone. Ex- amples of this class are found in the Donohoe prospects in the green- stone on the east side of McCarthy Creek and the prospects of the Alaska United Copper Exploration Company on the west side of Bowlder Creek, opposite the Westover claim, and on the east side of Bowlder Creek north of Dan Creek. The copper sulphides of the last-named locality occur along joint or fault planes, some of which are nearly parallel with the major strike fault of the Dan Creek valley and some cross these at large angles. In 1909 a tunnel was being driven on the property about one-fourth of a mile east of Bowlder Creek and 275 feet below the limestone-greenstone contact lo cut a fissure carrying copper minerals that was exposed 175 feet higher to the north. A belt of greenstone with disseminated copper sulphides is found at about this distance below the limestone and extends east along the north side of Dan Creek valley. It carries small amounts of bornite and chalcopyrite, and in places a little native copper is present. The native copper is believed to be a sec- ondary alteration product derived from the sulphide. Bowlders of greenstone earning native copper are not unusual in the gravels of Dan Creek. Not much work has been done on the native copper- bearing greenstone, and the quantity of copper there is not yet deter- mined. The principal prospects of this kind are on the upper part of Dan Creek and are the property of the Dan Creek Gold and Copper Company. A small deposit of copper carbonates, malachite, and azurite is found in the limestone only a few feet above the limestone-greenstone contact south of Chitistone River, a mile east of the Nizina River valley. The copper minerals were deposited in a crushed and faulted part of the limestone and the whole is much stained with iron oxide. Two short prospecting tunnels were driven in the limestone by the Houghton Alaska Exploration Company, to whom the prospect belongs. 70648°— Bull. 448—11 -7 98 THE NIZINA DISTRICT, ALASKA. GOLD. PRODUCTION. All the gold produced in the Chitina Valley has come from the placers of Dan, Chititu, and Young creeks. Chititu Creek is the principal producer, and after it comes Dan Creek. Young Creek has had only a small output up to the present time and may almost be disregarded as a contributor in past years, but with lower freight rates and cheapened cost of production it may become of greater im- portance in the future. The total gold production of Chititu and Dan creeks from 1903 to 1909, inclusive, may be estimated with a considerable degree of accuracy as between $450,000 and $500,000, or an average of about $65,000 a year. There is good reason to believe that with the installation of new equipment on the completion of the railroad this yearly average will be much increased. SOURCE OF THE GOLD. It may be said with certainty that the source of the placer gold of Dan, Chititu, and Young creeks is in the black shales of the Kenni- cott formation. This is clearly shown by the distribution of the gold itself. All the tributaries that flow into Dan and Copper creeks from the northeast, including Dan Creek above the mouth of Copper Creek, lie within the limestone-greenstone area and carry no gold. All the tributaries that flow into Dan and Copper creeks from the southwest head in the shale area and all carry gold. All the gravel deposits of Dan and Copper creeks except a part of the bench and stream gravels on lower Dan Creek are derived from sources within the drainage basin of these streams. No foreign material was found, and there is almost no possibility that any could be present, for the whole basin is surrounded by steep walls which probably never Avere below the surface of the ice fields during the time of greatest glaciation. All the tributaries of Chititu Creek originate within the black shale area and all carry gold, but here, as on Young Creek, part of the gravels are of foreign origin brought in by glacial transportation. Rex Creek is the one exception to this statement, for its gravels, save in the lower mile of its course, are all derived from within its own drainage basin. The gravels of the upper Rex Creek valley are derived from the black-shale area and carry gold. No evidence was obtained to indicate any other source for the gold of Chititu and Dan creeks than the shales lying between Dan and Young creeks, although all the copper and probably all or nearly all the silver of Chititu Creek came from an outside source. Many small quartz veins carrying pyrite and native gold have been found in the black Kennicott shales between Copper and Rex creeks. GOLD. 99 They range in thickness from less than an inch to several inches and are believed to have a close relation to the porphyritic intrusions in the shales. Molybdenite is present and stibnite is also reported from these veins. The placer gravels contain, besides the metals gold, silver, and copper, such heavy minerals as galena, cinnabar, barite, pyrite, and possibly marcasite. Native lead with a white coating, thought to be cerusite, was found in the sluice boxes on Chititu Creek, but may have been introduced by white men or natives, for bullets and shot are common. Not all of these minerals have been found in place in the rock, but it is probable that they also are associated with the quartz veins and porphyry intrusions. Thin veins no thicker than a sheet of paper are common in joint planes of the hard argillite bowlders in the stream gravels. They contain quartz, pyrite, and in places free gold. A thin vein less than one-fourth of an inch thick was found in a porphyry dike on the upper part of Rex Creek, which consisted of quartz with molyb- denite and pyrite and assayed 0.18 ounce gold and 12.80 ounces silver to the ton. The dike rock near the vein, although seemingly little altered, contained pyrite and showed a trace of both gold and silver. There is thus good evidence for the source of the gold aside from that furnished by its distribution in the gravels. The gold in the stream gravels is in part a concentration from the bench gravels through which the streams have cut their chan- nels and in part a concentration from the products of weathering derived directly from the shales and the auriferous veins. Probably the greater part is a reconcentration from the older deposits. Ex- tensive accumulations of high bench gravels are present on both Dan and Chititu creeks. They are best developed on the lower parts of the streams but extend into some of the tributary valleys. The bench gravels of Dan Creek extend west from the neighborhood of Copper Creek and around to the west slope of Williams Peak,® where they reach an elevation of over 1,200 feet above the flats of Nizina River. The bench gravels of Chititu Creek reach an eleva- tion as great as or greater than those of Dan Creek. In both places they represent a filling in old valleys through which the present streams have cut their channels and in so doing have reconcentrated a great volume of older deposits, derived partly from the upper Nizina Valley and the region east of the heads of White and Young creeks but chiefly from the drainage basin of Dan and Chititu creeks. When the bench gravels were laid down the two great ice streams that came down the Nizina and Chitina valleys were still in existence, although on the retreat. They formed the bar- rier behind which it was possible for such deposits to accumulate a Williams Peak is named in honor of John M. Williams, a pioneer prospector of the Nizina district, who was killed in a snowslide on Bonanza Creek on April 7, 1909. 100 THE NIZINA DISTRICT, ALASKA. and brought to the bench gravels that part of them which is foreign to Dan and Chititu creeks. It is impossible to say what proportion of the gravels consists of foreign material, but it is believed to be the smaller part. Some of the bench gravels carry gold in sufficient quantity to be of commercial importance, as has been proved at a number of places. A reconcentration of such deposits accounts in part for the greater richness of the stream gravels. The process that brought about this concentration is exactly the same in principle as that carried on in the miners’ sluice boxes on a much smaller scale but in a much shorter time. This concentration is probably slower at present than it was before the streams had cut through the deep gravel accumulations and intrenched themselves in the underlying hard rock, but it still goes on, for erosion of the bench gravels has not ended. PLACER DEPOSITS. DAN CREEK. Dan and Copper creeks may well be regarded as one stream in spite of whatever accident or design resulted in their having dif- ferent names and of the fact that the upper part of Dan Creek some- times carries as much or more water than Copper Creek. A refer- ence to the geologic map (PL III, in pocket) will show that the two streams follow closely the course of the fault that gave the older greenstone and the limestone on the north their relative ele- vation above the base of the Kennicott formation. With unimpor- tant exceptions, the north side of the Dan and Copper creek val- leys is in limestone and greenstone, the south side in shales of the Kennicott formation. Most of Copper Creek is in a broad glaci- ated valley, but at a point nearly 1 mile above its mouth the creek enters a narrow rock-walled canyon that opens slightly below Cop- per Creek yet extends down Dan Creek nearly a mile. Dan Creek valley below the canyon is narrow and shut in by steep mountains as far as the flats of Nizina River. During the ice invasion the Copper Creek valley was swept clear of whatever unconsolidated deposits may have accumulated, and the form of the valley was considerably modified. When the ice was retreating some glacial debris was left on the valley floor, but it is of less importance in connection with the gold placers than the accumulations of stream gravels that have been laid down since the glacier disappeared. In this respect the placers of Copper Creek are different from those of Dan Creek. All the tributaries of Copper Creek on its south side, as Idaho, Rader, and Seattle gulches, carry gold, but most of the output of the creek comes from near the mouth of Rader Gulch. Part of the gold is from the gulch itself and part is from Copper Creek, just GOLD. 101 below the gulch. The gravels are all shallow. Those in the mouths of the gulches are composed almost entirely of shale, chiefly from the Kennicott formation but also in part from the McCarthy shale. They occupy narrow gulches and accumulate so rapidly that the streams have difficulty in removing them. The gravel deposits of Rader Gulch are of this character. They consist of loose shale fragments and occupy only a few hundred feet of the lower end of the gulch, for above them the grade is so high and the channel so narrow that the water removes loose material rapidly. The gravels of the main stream contain material from all the formations within the drainage basin. At Rader Gulch they form a narrow flood-plain area between the mountain slope on the southwest and a low ridge on the northeast. They contain considerable coarse material mingled with blocks and bowlders of glacial origin and much fine material derived from the shales. The gold is not a concentration from older, lower-grade deposits but is derived directly by weathering and by stream concentration of the products of weathering. The source of most of the gold is clearly indicated by its position in the gravels at and just below the mouth of Rader Gulch and the presence of workable gravels on the lower part of Rader Gulch. Idaho and Seattle gulches resemble Rader Gulch in their form and the character of their gravel deposits, but they have not been found to carry as much gold. Copper Creek is difficult to reach with supplies except in winter, for the canyon makes necessary a high climb of more than 1,000 feet around the side of Williams Peak. Men on foot, however, can fol- low the creek. Logs have been placed across the stream in the can- yon and make it possible to avoid bad places. Mining on Copper Creek is done with pick and shovel. There is a small supply of timber for firewood and for sluice boxes, but it would not be ade- quate for extensive mining operations. Good timber for lumber can be secured along Nizina River, but the expense of carrying it to Copper Creek under present conditions, except in winter, would be great. The gold of Dan Creek has a less simple history than that of Cop- per Creek. It is in part a reconcentration from older gold-bearing bench gravels and in part, like that of Copper Creek, a concentration from the products of later erosion. Old high-bench gravels are found on both sides of Dan Creek, especially on the lower part, but near the west end of the canyon they lose their prominence and dis- appear altogether at or below the mouth of Copper Creek. Dan Creek has cut its present channel down through this great accumu- lation of glacial and stream deposits and into the shales beneath. The stream gravels consist of greenstone, limestone, and shale. They form between rock walls a narrow flood plain overgrown with timber 102 THE NIZINA DISTRICT, ALASKA. and in many places of less width than a placer claim. A large part of the gravels consists of bowlders ranging from cobbles to masses several feet in diameter. Most of them, however, are not too large to be moved by hand. All the fragments are rounded. They were deposited by a rapidly flowing current and the bedding is poor. Buried spruce logs and fragments of wood are common. The gravel and its slight covering of soil range from 8 to 12 feet in depth. Dan Creek gold is coarse and smooth and is accompanied by silver and copper. It has been concentrated on bed rock or within the lower 2 feet of the gravel. A large proportion, however, finds its way into the cracks and crevices in the shale, so that in places a foot or more of the shale has to be removed to recover all the metal. An unusual feature of the gravels of Dan Creek is the small quantity of fine gold found in them. Very little fine gold is recovered in the sluice boxes and practically none is found in panning. Numerous prospect holes show that the gold is well distributed across the chan- nel and have failed to discover the presence of a concentration into a defined pay streak. Beside the holes sunk on the flood plain, tunnels have been driven along bed rock at the base of the bench gravels above the present flood plain. The depth to which the creek has incised itself in the shales is not constant but is rarely less than 10 or 15 feet. Thus the base of the bench gravels or the “ rim ” of the channel stands well above the creek. The tunnels driven in the bench gravels show the presence of gold in sufficient amount to be of commercial importance and in several places in sufficient amount to pay for extraction under the expensive methods necessary in pros- pecting the gravels, but the final test of value will come when an attempt is made to extract the gold on a large scale. An old channel formerly occupied by Dan Creek lies in the bench gravels on the south side of the present stream. It runs on the south side of the small round hill west of the mouth of Copper Creek and follows the hillside to the west, but it has not been traced definitely. Doubtless much of it has been removed by erosion. Its gravels carry gold, and an attempt has been made to exploit them in a small way, but without great success. Dan Creek is favorably situated with reference to timber for mining purposes and has a good supply of water. It is reached without any difficulty from the Nizina, and a wagon road for hauling timber and supplies has already been built. All mining to the present time has been by the simplest methods. The one employed for several years is to undercut the bank with a stream of water and by washing away the gravel to leave the gold. Bowlders and small rocks are piled parallel with the bank and only a few feet from it. Then wafer controlled by dam and gates is turned in and forced against the bank, undercutting it and carrying away most of the fine gravel. The large GOLD. 103 rocks are piled back by hand and the remaining fine gravel and gold are shoveled into sluice boxes, after which bed rock is cleaned. Prep- aration has been made for installing a hydraulic plant on Dan Creek, and it will be put in place as soon as the railroad is completed and better facilities for carrying freight are established. CHITITU CREEK. Chititu Creek and its two branches, Rex and White creeks, lie wholly within the area of Kennicott sediments. These streams, like Dan Creek, have cut their present channels through the old valley filling and entrenched themselves in the black shales. The amount of this entrenchment is variable, ranging from nothing below the canyon on Chititu Creek to 60 or TO feet on White Creek, but the increase is not uniform. It is about 30 feet at the mouth of White Creek, but is greater than that in places farther down on Chititu Creek. It decreases as Rex Creek is ascended and also on the head of White Creek. The canyon on Chititu Creek is due to the presence of a large porphyry dike in the black shales, which has protected them from rapid stream cutting and confined the water to a narrow chan- nel. The canyon is small but marks the downstream limit of gold- bearing gravels that are now considered of commercial importance. Above the rim of the shallow trench cut in the shales by the stream are steep banks of rudely assorted gravels. The top of the gravel bluff at Sunday Gulch is a little more than 500 feet above Chititu Creek. Half a mile downstream the top of the bluff is 750 feet above the creek, but from this point on the difference grows smaller till the bench gravels merge into the gravels of Nizina Valley a short distance below the canyon. Bench gravels are prominent on Rex Creek for a mile or more above its mouth, but they either were not deposited or have been removed from the upper end of the creek, where the unconsolidated accumulations are wholly glacial debris. A large part of the bench deposits of White Creek have been eroded away, yet they extend up the creek in conspicuous exposures for at least 2 miles. The richest gold-producing gravels of Chititu Creek are the stream gravels ; they include all of Chititu Creek above the canyon, together with a large part of Rex and White creeks. The most important parts of these creeks, viewed from the standpoint of gold production, are represented on the sketch map (fig. 10). The stream gravels cover the floor of the shallow rock-rimmed trench to a depth of 8 to 16 feet, depending partly on the form of the bed-rock surface and partly on the irregularities of deposition by a swiftly flowing current. They form a flat, originally covered with timber and under- brush, ranging in width from 200 to 700 feet. The gravels of Chititu and White creeks and of the lower part of Red Creek consist of 104 THE NIZINA DISTRICT, ALASKA. shale, limestone, sandstone, and quartz diorite porphyry, all of local origin, mingled with greenstone, diorite, and other rocks brought in by glacial ice from a foreign source. Shale, sandstone, and porphyry make up the fragmental deposits of the upper part of Rex Creek. a o 'O a a m a o be a £ o .a os GJ a Bowlders and large blocks make up a considerable portion of the gravel deposits, but not so large a proportion as on Dan Creek. Some of the glacial erratics are 6 or 8 feet in diameter. Most of the bowlders, however, can be sent through the sluice boxes, although it is necessary to break part of them with powder. of bench and stream gravels. GOLD. 105 The gravels producing gold at present include those of Chititu Creek and of the lower part of Rex Creek. Very little work aside from that necessary to hold the claims has been done on White Creek for several years. In a general way the gold of Chititu Creek is dis- tributed through the gravel from rim to rim of the rock channel, but it was found that at one place near the canyon there is a very well-defined pay streak, such as had not been found before on any of the claims farther up the creek. Most of the gold is on or near bed rock. Very little of it is found in the upper part of the gravel. The gold penetrates the bed rock through cracks and all openings, so that it is necessary to clean the rock carefully by hand after taking up the loose upper part to the depth of a foot or more. There are considerable differences in the character of the bed-rock surface, owing to irregularities in form and differences of hardness. In places the old stream has worn the rock smooth or has hollowed out cavities and depressions. Differences in the depth of weathering also add to the irregularities of the exposed surface, for the streams of water from the hydraulic giants cut away the loose rock and leave the harder parts standing in relief. Without doubt much of the gold of Chititu, Rex, and White creeks is a concentrated product from the bench gravels and the remainder is derived directly by weathering from the surrounding shales. All the bench gravels carrj gold in some amount, and with decreased cost of mining it is prob- able that some of them will be exploited. Chititu gold is finer and less worn than that of Dan Creek. It was found on the lower part of Chititu Creek that in a set of 4 screens ranging from 10 to 20 mesh about equal amounts of gold, by weight, were caught in each screen; at the mouth of Rex Creek it was estimated that from 25 to 40 per cent of the gold passes through a 16-mesh sieve. These results are in marked contrast with the heavy coarse gold of Dan Creek, yet both come from the same area of mineralization. There is, nevertheless, a little coarse gold on Chititu Creek, and several large nuggets have been found. The gold assays about $18.70 per ounce when cleaned. A large quantity of copper is obtained in the clean-up, and nuggets of native silver are common. Several other heavy minerals besides copper and silver are caught in the sluice boxes, such as pyrite, galena, stibnite, barite, and lead. Most of the lead w T as evidently introduced through the use of firearms, but some of the pieces examined did not resemble the battered bullets found in the sluice boxes and had a thick white coating of oxidized material. One of the largest of the native-silver nuggets was found in 1909 ; it weighed over 7 pounds but contained considerable quartz. Native copper is a source of considerable difficulty and expense in mining. Several hundred pounds of fine copper are secured at every 106 THE HIZINA DISTRICT, ALASKA. clean up and many large masses are taken from the cuts. Occasion- ally a large piece goes through the boxes and into the dump, but the largest are too heavy to be driven out of the cut by the giant. All the gold is picked over by hand to remove the fine copper not sepa- rated in the sluice box. During the early days of mining no effort was made to save the copper, since the expense of carrying it to the coast was greater than its value, yet with railroad transportation it should now be worth considering. For the first few years after the discovery of gold on Chititu Creek mining was conducted on Rex and White creeks as well as on Chititu Creek. Rich ground was found on all these streams, and the prin- cipal operations were on the upper half of Chititu Creek, the lower end of Rex Creek, and the upper part of White Creek. All the work was done by hand and attention was directed to the richest ground only. At present two hydraulic plants are in operation, one on Chititu Creek and the other at the mouth of Rex Creek. Most of the claims on Chititu Creek are owned by the Nizina Mines Com- pany and a complete hydraulic plant has been installed to exploit Figure 11. — Diagram showing the method of operating hydraulic giants on Chititu Creek. them. This plant includes flumes, pipe lines, and giants, as well as a complete sawmill and an electric lighting system. The sawmill is equipped with planers and machinery for turning out standardized parts of flume and sluice boxes and riffle blocks and for putting them together. There is also a blacksmith shop and equipment for han- dling iron pipe. A very unusual feature for an Alaska placer mine is the complete system of accounting by which all expenses are charged in their proper place and the cost of any part of the operations is made known. The method of handling gravel in the pit is shown in figure 11. When the sluice boxes have been put in place a bed-rock flume is carried upstream in the gravels as far as desired. Then the upper end of this cut is widened to 100 or 150 feet and a giant is placed on either side so as to drive the gravel along the sloping face into the head of the flume. By this method the force of the giants is added to the ground sluice water and a decided gain in efficiency is ob- tained over the former method of working against the face with the giants turned upstream and away from the sluice boxes. In practice GOLD. 107 only one giant is used at a time, the opportunity thus being given for a gang of men to remove the large bowlders on the opposite side. A giant is also required at the lower end of the sluice boxes to stack the tailings and keep the end of the boxes clear. Mining operations at the mouth of Rex Creek have been con- ducted by Frank Keman with a smaller plant than that on Chititu Creek, bur they have been carried on for a longer time. A small giant is used and water is brought from Rex Creek in a flume. The conditions here are about the same as on Chititu Creek, but the width of gravel between the rock rims is less. Some very rich ground has been found on the lower end of Rex Creek and just below that on Chititu Creek. The canyon of Chititu Creek is 4-J miles from the flats of Nizina River, and the character of the country is such that a good wagon road could be constructed at moderate expense. Such a road in con- nection with a bridge over the Nizina River would make communi- cation with the railroad at Kennicott River easy and would be of great advantage to the miners of Chititu Creek, since it would enable them to secure supplies at any time of the year at a reasonable cost. It would also do much to solve the problem of securing labor at the time when it is most needed and thus prevent the necessity of carry- ing a large force of men on the pay roll during the whole season. Labor is a large item in the expense of operation at present chiefly because of the large amount of time spent in winter freighting. Wages range from $90 per month and board bo $5 per day, with an additional amount to foremen. Chititu Creek has a sufficient volume of water for all the demands that are made on it by the hydraulic plant in operation. The supply on Rex and White creeks is naturally less and probably would be inadequate for a large plant at some seasons of the year. Chititu Creek has a fall of 180 feet per mile from the forks to the canyon. Rex and White creeks have a fall of 250 feet per mile in the lower 2 miles of their courses. Thus a good head of water can be secured on each of these streams. There is an abundance of good timber for lumber and mining purposes on Chititu Creek below the canyon. YOUNG CREEK. Young Creek resembles Dan and Chititu creeks in having cut its channel through an old gravel filling in a glaciated valley. The present stream flows in a trench cut in black shales and lies from 20 to 40 feet below the base of the bench gravels. Its channel is in reality a shallow canyon whose walls are shale at the base and gravel above. Young Creek valley was once occupied by a glacier which came into it across a broad low divide near its head and was an over- flow branch of the great Nizina Glacier. The gravels of Young Creek 108 THE NIZINA DISTRICT, ALASKA. therefore contain a large amount of foreign material from the upper Chitina Valley in addition to rocks of the Kennicott formation and the greenstone from its own valley. A large part of the creek has been staked for placer gold, although the production has not } 7 et been enough to give much encouragement for mining. Two men were prospecting on the lower part of the stream in 1909. In previous years work was done on Calamity Gulch also, but the results were not sufficiently favorable to lead to its continuation. Young Creek carries a large stream of water at all seasons of the year and has an average fall of 100 feet per mile above the Nizina flats. It is difficult to reach the upper part of the creek because of the canyon-like character of the stream channel and of the absence of trails above the creek on the hill slopes, and for this reason it is customary to cross the ridge from the head of White Creek and come down on Young Creek at the head of Calamity Gulch. This is the route always followed by prospectors bound for the head of Young Creek. INDEX. A. Page. Alaska, northern, rocks of, correlation of 26-27 Alaska, southeastern, rocks of, correlation of. 26-27 Alaska Peninsula, rocks of 42 rocks of, correlation of 26-27 Alaska Range, rocks of, correlation of 26-27 Alaska United Copper Exploration Co., pros- pects of 97 Amazon Creek, rock glacier on 58 Azurite, occurrence of 79 B. Bibliography of area 13 Birch, Stephen, weather observations by : . . . 13 Blei Gulch, rocks on 34-35,36 Bonanza Creek, fossils from 24 rocks on 62 Bonanza Extension Claim, description of 92 Bonanza mine, copper from 76,80 description of 84-90 discovery of 76 faults at 69-70,85 map of 87 ores of 86-90 section of, figures showing 88,89 rock glacier near 58 view of 58 rocks at 62, 84-85 view of 84 workings at 84,87-88 Bornite, occurrence of 78-79,82 Bowlder Creek, copper on 97 Brooks, A. H., preface by 7-8 C. Calamity Gulch, rocks near 35 Canyon Creek, rocks on 71 Capps, S. R., work of 13 Chalcocite, occurrence of . 78-79 Chalcopyrite, occurrence of 78-79,82 Chinitna Bay, rocks near 42 Chitina Glacier, description of 45-46,48 Chitina region, copper of, survey of 7 Chitina River, description of 9 valley of, climate of 14 copper of 77-80 formation of 74-75 glaciation in 45-46 map of Pocket. rocks in 25,30,32,34,37.43,62,71 Chitistone limestone, age of 23-27 character of 11, 19, 20, 21-27 copper in 78-79 deposition of 72 distribu"' ion of *. 22-23, 70 fossils o 24-25 Page. Chitistone River, copper on 80 description of 10 fan of 51 fossils from 24-25 rocks on and near 22, 61-62, 73 Chititu Creek, copper on 79-80 description of 10,20 fan 51 fossils on 39 glaciation on , . . . 46, 47, 48, 49 gold on 76,98,103-107 gravels of 99-100 hydraulicking on, figure showing 106 map of, showing placers 104 rocks on and near 36, 37, 60, 103 Chitty Creek, fossils from 38 Climate, character of 13-15 Coal, occurrence of 73-74 Columnar section, figure showing 11 Cook Inlet region, rocks of 42-43 rocks of, correlation of 25,26-27 Copper, discovery of 75 occurrence of 75-76, 105-106 mode of 8,77-81 production of 76 source of 81-83 Copper Creek, fault on 68 fossils from 30,36,40 glaciation on 48 gold on 100-101 rock lenses on, figure showing 65 rocks on and near 9, 34, 37-38, 66, 100 view of 18 Copper properties, description of 83-97 groups of 83 Copper River, basin of, descriptiqp of 14 basin of, map of 9 rocks in 73-74 climate of 14-15 Correlations, table of 25-27 Covellite, occurrence of 79 Cretaceous rocks, correlation of 26 Cross, W., and Howe, E., cited 54-55 D. Dan Creek, copper on 79-80, 83, 97 description of 10 fan on 51 fault on 68-69 fossils from 30, 40 glaciation on 46 gold on 76,98,100-103 gravels on 49, 99-100 rocks on and near 22, 23, 29, 34, 36, 37-38, 61, 62, 66, 100 Diorite. See Quartz diorite. Donohoe prospects, location of 97 Drainage, description of 9-10,20 109 110 INDEX. E. Page Eagle Creek, rocks on 34 Economic geology, description of 75-108 Elevations, altitude of 10,18 Elliott Creek, rocks on 23 Enochkin formation, correlation of 26 description of 26,42 Erie claim, description of 91-92 Erosion, effects of 51-52, 72 Explorations, description of 12-13 F. Falkland Islands, rock streams in 54 Faulting, occurrence and character of 12, 68 Field work, extent of 13 Fissure veins, occurrence of 77, 79 Folding, occurrence and character of 12 Forage, character of 15 Fourth of July Creek, rocks on 73 Fractures, relation of, to copper 8 Freighting, cost of 17 G. Geography, description of 9-10 Geology, description of 11-12,20-26 Geology, areal, description of 70-71 Geology, economic, account of 75-108 Geology, historical, sketch of 71-75 Gerdine, T. G., work of 12 Glacial epoch, events in 43-48 Glaciation, effects of 18-19 Glacier Creek, rocks on 61 Glaciers, rock, description of 52-59 occurrence of 15 origin of 53-59 Gold, discovery of 76 placer deposits of, descriptions of 100-108 production of 98 source of 98-100 Gravels, occurrence and character of 20, 49-51 Greenstone. See Nikolai greenstone. Greenstone-limestone contact, copper along . . 8 H. Historical geology, sketch of 71-75 Houghton Alaska Exploration Co., copper prospects of 97 Howe, E.. cited 54-55 I. Idaho Gulch, gold in 100-101 rocks near 34 Igneous rocks, distribution and character of. 59-67 intrusion of 11,20 Independence claim, description of 92 Indians, homes of 16 J. Jumbo claim, description of 90-91 ore body of, section of, figure showing 91 Jumbo Creek , fossi Is from 24 Jurassic rocks, character and distribution of 11,31-43,63-67 columnar sections of 31,37 correlation of 26 gold in 8 K. Page. Kennicott formation, age of 38-43 character of 11,19,20,31-42 columnar section of 31,37 correlation of 26,31 deposition of 72-73 distribution of 36-37, 70-71 fossils from 38-41 gold in 8, 98-99 views of 32,64 Kennicott Glacier, breaking of 14, 47 description of 47-48 fault at 68-69 rocks at and near 22, 34, 62, 73 Kennicott River, description of 10 Knopf, A., and Paige, S., cited 67 Kotsina River, copper on 80 rocks on 23,30,62 Kuskulana River, rocks on 30 L. Lead , occurrence of 99 Limestone contact. See Greenstone- lime- stone contact. Literature, list of 13 Little Nikolai Creek, rock glacier on, view of. . 56 Location of area 9 map showing 9 Lowlands, deposits of. 20 description of 20 M. McCarthy Creek, correlation of. 30 description of 10, 19, 20, 47 fan on, view of 18 fault on 69 fossils from 30,39 glaciation on 47-48, 49 gravels on 49 rock glacier on 56-59 view of 56 rocks on 21-22, 23, 28, 29, 31, 33, 62, 70 valley of 51 McCarthy Creek glacier, description of 47-48 McCarthy Creek shale, use of term 22 See also McCarthy shale. McCarthy shale, age of 30 character of 11, 19, 20, 28, 29-30 correlation of 27 deposition of. 72 distribution of 28-29 fossils of 30 Maddren, A. G., and Moffit, F. H., work of. . 12, 13 Map of Copper and Chitina valleys 9 of Nizina district Pocket. Map, geologic, of Nizina district Pocket. Marvellous claim, description of 92-93 Matanuska district, rocks of. 42, 43, 73-7 4 rocks of, correlation of 26-27 Mendenhall, W. C., work of. 12 Mining, history of 75-76 Moffit, F. H., and Maddren, A. G., work of. . 12, lo N. Nabesna- White River district, rocks of, corre- lation of 20-27 Naknek formation, correlation of 26 description of 26, 42 INDEX, 111 Page. National Creek, rock glacier on 57 view of 56 rocks on 62 Native copper, occurrence of 79-80, 105-106 Nikolai claim, description of 93-95 map of. 94 Nikolai copper lode, discovery of 75 exploitation of 76 rocks near, view of 32 Nikolai Creek, fault on 68-69 fossils from 24-25, 30, 46 glaciation on 48 rocks on and near 22, 31, 32, 33, 36, 37, 62, 66 view of 32 Nikolai greenstone, age of 63 character of 11, 20-21 , 59-62 copper in 77-80, 81 distribution of 61-62, 70-71 effusion of 71-72 Nizina district, copper of, survey of 7 geologic map of Pocket. map of Pocket. Nizina Glacier, breaking of 14 description of 46-47 Nizina River, description of 9, 20 flood plain of 50 glaciation on 46-47 rocks on 21, 22, 23, 28, 31, 37, 61-62, 66, 70 view of : 22 valley of, formation of 75 Nutzotin Mountains, rocks of 42 P. Paige, S., and Knopf, A., cited 67 Physiographic record, interpretation of 74-75 Placers, gold, description of 100-108 Pleistocene epoch , events in 43-48 Ponds, occurrence of 20 Population, character of 16 Porphyry Peak, rocks of 37, 66, 71 view of 64 Preglacial time, conditions in 43 Pyramid Peak, rocks of 34 Q. Quartz diorite porphyry, age of 66-67 character of 63-66 distribution of 66,70-71 intrusions of, views of 64 Quaternary deposits, character of 11, 20, 49-59 deposition of 43-59 R. Rader Gulch, gold in 100-101 Railroads, construction of 17-18 Relief, description of 18-20 Replacement deposits, occurrence of 77-79 Rex Creek, fossils from ' 40-41 glaciation on 46,47,49 gold on 99,103-107 gravels of 98 map of, showing placers 104 rocks on 34, 36-38, 66, 68 Rock glaciers, description of 52-59 occurrence of 19 origin of 53-59 Rohn, Oscar, work of 8, 12 S. San Juan Mountains, Colo., rock streams in... 54-55 Schrader, F. C., work of 71 Page. Schrader, F. C., and Spencer, A. C., cited 62 work of 12, 25 Seattle Gulch, gold in 100-101 Sedimentary rocks, description of 20-59 Silver, occurrence of 80 Skolai Creek, rocks on 25 Skolai Pass, rocks in 25 Sourdough Peak, rock glaciers on 58 rocks of 37,40,66,71 Spencer, A. C., and Schrader, F. C., cited. . . 62 work of 12,25 Stanton, T. W., fossils determined by 23-25, 30, 38-40 Stratigraphy, description of 20-67 Stream erosion, work of 43 Stream gravels, distribution and character of. 50 Structure, description of 12,67-70 map and sections showing Pocket. T. Talkeetna district, rocks of 42, 43 rocks of, correlation of 26-27 Talus, fans of 19 Temperature, records of 13-15 Texas Creek, glaciation on 48 rocks on 29,40,61 Till, distribution and character of 48 Timber, character of 15-16 Topography, description of 18-20 Trails, description of 16-17,20 Transportation, cost of 17 methods of 16-18 Triassic rocks, character and distribution of. . 11, 20-30, 59-63 correlation of 27 view of 18 U. Unconformity, occurrence of 20,29,36 view of 36 V. Vegetation, character of 15-16 W. Westover claim, description of 95-97 ore of 83, 95-97 White Creek, fossils from 41 gold on 103-106 glaciation on 46 map of, showing placers 104 rock glacier on 58 rocks on 34,36 White River, copper on 79-80 White River-Nabesna district, rocks of, cor- relation of 26-27 Williams Peak, rocks of 37 Witherspoon, B. C., work of 7, 12 Wrangell Mountains, description of 10 geology of 10 Y. Young Creek, description of 10 fault on 69 fossils from 41 glaciation on 47, 48, 49, 50 gold on 76,98,107-108 rocks on and near 35-36, 38, 60, 66, 71 Yukon Basin, rocks of 41,43 rocks of, correlation of 26-27 O DEPARTMENT OF THE INTERIOR UNITED STATES GEOLOGICAL SURVEY GEORGE OTIS SMITH, Director Bulletin 449 A GEOLOGIC RECONNAISSANCE IN SOUTHEASTERN SEWARD PENINSULA AND THE NORTON BAY-NULATO REGION ALASKA BY PHILIP S. SMITH AND H. M. EAKIN WASHINGTON GOVERNMENT PRINTING OFFICE CONTENTS. Page. Preface, by Alfred H. Brooks 7 Introduction 9 Geography '£ 11 Location of area 11 History of exploration 12 General topography 17 Drainage basins included IS Yukon basin 19 Norton Sound drainage 20 Tributaries east of Koyuk River 20 Koyuk River 24 Tributaries west of Koyuk River 25 Kotzebue Sound drainage 28 Uplands 28 Coastal features 30 Vegetation and game 32 Climate 35 Temperature v 35 Precipitation 36 Wind 37 Settlements and population 38 Descriptive geology 39 Undifferentiated metamorphic rocks 39 Area east of the Yukon 40 Southeastern Seward Peninsula 40 Character and distribution of rocks 40 Kwik River area 41 Area north of the Koyuk 42 Bendeleben Mountain area 42 Area south of the Niukluk 44 Area west of the Darby range 44 Summary 45 Paleozoic rocks 46 Area east of the Darby range 46 Fish River area 49 Omilak mine area 51 BJuff— Topkok Head area . 52 Area at head of the Mukluktulik 53 Summary 54 Cretaceous sedimentary rocks 54 Ungalik conglomerate 55 Shaktolik group 57 Lower division 57 Upper division 60 3 4 CONTENTS. Descriptive geology — Continued. Page. Igneous rocks 60 Pre-Cretaceous 61 Metamorphic igneous rocks— 61 Nonmetamorphic igneous rocks 64 Post-Cretaceous 70 Intrusive rocks 70 Effusive rocks 71 Veins 76 Unconsolidated deposits 76 Unsorted deposits 76 Deposits of transported material 77 Marine gravels 78 River gravels 79 Glacial deposits 83 Age of the unconsolidated deposits 85 Structural geology 86 Historical geology 93 Economic geology 100 Placers 101 Gold in areas of unmetamorphosed sediments 101 Conditions of placer formation 101 Placers of the Bonanza Creek region 105 Gold placers in areas of metamorphic rocks 109 Distribution 109 Koyuk River basin 110 Kwik River basin 115 Tubutulik River basin 115 Kwiniuk River basin 116 Fish River basin 116 Main stream 116 Council region 117 Bluff region 123 Buckland River basin 125 Kiwalik River basin 126 Summary 127 Lode prospects 127 Gold 128 Silver-lead 130 Copper prospects 134 Coal resources 136 Yukon basin 136 Norton Bay basin and southeastern Seward Peninsula 139 Conclusions regarding coal resources 140 ILLUSTRATIONS. Page, Plate I. Reconnaissance map of southeastern Seward Peninsula In pocket. II. A, Asymmetric valley, Shaktolik Basin ; B, uplands between East Fork and Inglutalik 22 III. A, Characteristic mountain topography, Darby Range; B, East coast of Darby Peninsula 30 IV. Map showing distribution of timber , 32 V. Geologic map of Nulato-Norton Bay region In pocket. VI. Geologic map of southeastern Seward Peninsula In pocket. VII. Geologic map of Omilak region 44 VIII. A, B, Paleozoic limestone, Darby Peninsula, intruded by green- stone and by granite 46 IX. A, Limestone and schist at Omilak mine; B, General view of Darby Range from south 50 X. A, Sandstones and shales of Shaktolik group on Shaktolik River ; B, Concretions in sandstones of the Shaktolik group. _ 56 XI. A, Surface markings on sandstones of the Shaktolik group, Inglutalik divide; B , Granite pinnacles north of Kwiniuk River 58 XII. A, Inclusions, east coast Darby Peninsula ; B, Venation in lime- stone, east coast of Darby Peninsula 66 XIII. A , Folded limestone near Omilak mine; B, Folded and shat- tered limestone on Ophir Creek 90 Figure 1 . Sketch map of northwestern Alaska, showing location of region considered 12 2. Arrangement of drainage due to geologic structure 23 3. Profile of hill north of camp C7, at head of Tubutulik River 29 4. Relation of greenstone, limestone, and slates, east coast of Darby Peninsula 62 5. Cliff exposures near mouth of Daniels Creek, Bluff region 63 6. Sketch map of the vicinity of the Omilak mine 64 7. Diagram showing relations of glacial material on Etchepuk divide L 85 8. Diagrammatic section west of Traverse Peak 87 9. Diagram showing folding in two directions 91 10. Diagrammatic summary of geologic history of Nulato-Council region 100 11. Diagrammatic cross section of the Nulato-Norton Bay region during Cretaceous deposition 103 12. Sketch map of Alameda Creek 110 13. Sketch map and section of Daniels Creek placers 123 14. Map showing location of placer camps on Bear Creek 125 15. Diagrammatic section of impregnated zones, Bluff region 129 PREFACE. By Alfred TI. Brooks. For several years after the organization of the Alaskan surveys in 1898 most of the appropriation was devoted to exploration. These exploratory surveys, although they had no high degree of accuracy, served to block out the larger features of the topography and geology, and the resulting reports and maps proved of great value to the pioneer prospector and miner. With the advance of the mining in- dustry came a constantly increasing demand for maps which were based on a higher degree of refinement both with reference to geo- logic observation and to mensuration. To meet this demand areal surveys were begun first on a scale of 4 miles to the inch and later, where the mining interests warranted it, on a scale of 1 mile to the inch. The rapid industrial advancement in many parts of Alaska led to the expansion of surveys of this character almost to the exclusion of the purely exploratory work. The progress made in reconnaissance and detailed surveys has seemed to warrant again diverting a part of the funds to exploring some of the little known regions. One of the largest of the un- surveyed areas in the more accessible parts of Alaska is roughly blocked out by lower Yukon and lower Koyukuk Rivers on the east and Norton Bay and Seward Peninsula on the west. This field was selected for survey because it was thought that the metamorphic rocks of the Seward Peninsula might occur within it, which would give presumption of the presence of auriferous deposits. The results of the investigation of this area are presented in this report. In addition to exploring the region east of Norton Bay the party also extended the topographic and geologic mapping into the south- eastern part of the Seward Peninsula, thus extending the surveys of Peters and Mendenhall, made in 1900. In this part of the field the results were sufficiently definite to warrant their publication in a map on a scale of 4 miles to the inch. The remainder of the survey, based as it was on foot traverses, which afforded little opportunity for areal mapping, seemed hardly sufficiently accurate to warrant the publica- tion of maps on a larger scale than 16 miles to the inch. 8 PREFACE. Messrs. Smith and Eakin deserve great credit for the large amount of information gleaned during their very hasty exploration. The re- sults form a notable contribution to the geology and geography of a region that was previously almost unknown. Though the economic results so far as most of the region is concerned are largely negative, they are, nevertheless, of no inconsiderable value. The geologic maps will indicate large areas which do not seem worthy of attention on the part of the prospector. Besides covering the Norton Bay and lower Yukon region in an exploratory way, the report and its maps furnish the details about the southeastern part of the Seward Peninsula necessary to complete the reconnaissance work in that province. The publication of this report marks the close of the reconnaissance work in the Seward Peninsula which was begun a decade ago. A GEOLOGIC RECONNAISSANCE IN SOUTHEASTERN SEWARD PENINSULA AND THE NORTON RAY-NULATO REGION, ALASKA. By Philip S. Smith and IT. M. Eakin. INTRODUCTION. West of Koyukuk and Yukon rivers a large area has long remained geologically unexplored. In a portion of this region an exploration party from the United States Geological Survey worked during the season of 1909, and the results of the studies there carried on and ex- tended as far as Council, in Seward Peninsula, are set forth in this report. The party consisted of the writers, A. G. Winegarden, packer, and a cook. Supplies for a month were shipped to Nulato, the point from which the expedition set out, and the camp equip- ment and supplies were transported in the field by a pack train of four horses. Other supplies, sufficient to last the rest of the season, were sent to Nome and then transported, through the courtesy of the Wild Goose Company, to the mouth of the Ivoyuk and there cached to await the arrival of the party. After many delays the party arrived in Nulato on the afternoon of June 24 and immediately began to get the outfit into condition for the trail. On the morning of June 26 active field work was begun. The route, as indicated by the location of the camps on the maps (Pis. I and Y, in pocket), was westward to Ungalik River, thence northward to the Ivoyuk, w T hich was reached on July 16. Here a halt was made until supplies from the cache could be obtained and the outfit put into shape for the next trip. On July 19 the party started northeastward along the divide between the Inglutalik and the Koyukuk drainage basins. This survey was carried eastward to the divide between Ivateel and Inglutalik rivers. Return to the Ivoyuk was made along the divide between the drainage basins of the Buck- land and the East Fork of the Ivoyuk, and a tie was made on the previous geological work of Moffit in northeastern Seward Penin- sula. At the close of the trip the Ivoyuk was crossed near the mouth of East Fork, and the party arrived at the Ivoyuk cache on August 8. A severe storm and the work of replenishing supplies and making 9 10 RECONNAISSANCE IN SEWARD PENINSULA AND necessary repairs delayed setting out again until August 12, when the party got under way and made a meandering traverse of the areas between Koyuk River and Norton Sound that had not been visited by Mendenhall in his expedition of 1900. Moving along the divide between the Koyuk and the Norton Sound drainage basins, the party swung around the head of the Tubutulik, thence crossed the divide into the Fish River drainage basin, and, following along the foothills, came to the Omilak mine. From the mine the course was southeastward to the Kwiniuk and thence along the coast to Walla Walla. Supplies had been sent to this point from the mouth of the Koyuk, so that the horses had been able to travel light. From Walla Walla meandering traverses were made westward to Cheenik, which was reached September IT. By this time the top of the ridges were snow covered, and a start was made the next day for Council by wav of the Kachauik-Fish River divide. Council was reached and the fieldwork for the season was stopped on September 21. Locations were kept by continuous foot traverses run b}^ each of the geologists independently and elevations were frequently noted by aneroid barometers. The barometric observations, however, were un- checked and served principally to give relative elevations. The foot traverses were paced, directions being obtained by means of Brun- ton compasses. The results of the different traverses were platted in the office by making adjustments between known points which had been determined instrumentally either by the Coast and Geodetic Survey or by Peters on the reconnaissance trip of Mendenhall in 1900. So closely did the various traverses check on known points that it P believed that, after the adjustments were made and the map prepared, few, if anjr, points were more than a mile out of their correct posi- tions. That this apparently rough method of pacing is capable of giving good results is shown by the fact that the difference between the position of Camp A15, near the Bonanza mine, on the Ungalik, as determined by the two geologists, after having made a linear trav- erse of over 130 miles, was less than 5 miles. This result was ob- tained on the erroneous premise that both were pacing 2,000 paces to the mile. When, however, an individual rating had been obtained by comparing the scaled and paced distance to the mouth of the Koyuk and this correction had been applied to the location of Camp A15, it was found that the difference between the two traverses was consider- ably less than 1 mile. Hearty acknowledgments are due to Mr. A. G. Winegarden, of Gardiner, Mont., who acted as packer throughout the various trips, for his unceasing activity in furthering the aims of the expedition and his willingness to perform more than his share of the camp work in the face of rather discouraging conditions. Thanks are also ex- pressed for the friendly assistance of Mr. C. H. Munro, of the Wild NORTON BAY-NULATO REGION, ALASKA. 11 Goose Company, and to Messrs. Thomas Moon and John Lindburg, prospectors, in distributing supplies at appointed places and thus facilitating the movements of the party. The writers desire also to express their appreciation of the work of the earlier geologists and engineers who have visited portions of the region or contiguous areas, and from whose published reports and manuscripts they have borrowed to supplement their own observa- tions. Among those to whom the writers are most indebted for scien- tific information are Messrs. J. L. McPherson, W. C. Mendenhall, F. C. Schrader, F. H. Moffit, and A. H. Brooks; for the determina- tion of the fossils collected they are indebted to the paleontologists of the United States Geological Survey. GEOGRAPHY. LOCATION OF AREA. The area in which new geographic and geologic information has been obtained may be inferred from the description of the itinerary of the expedition of 1909. It has seemed feasible, however, to so extend the area actually visited as to include contiguous regions which throw light upon parts of the region visited in 1909 or in which the results of 1909 serve to confirm or explain problems raised by other investigators. The area treated in this report is therefore in the main rectangular and may be roughly described as bounded by parellels 64° and 66° north latitude and by meridians 156° and. 164° west longitude. Described in terms of places and natural objects, the southern margin is near the settlement of Unalaklik, on the east coast of Norton Sound, and the eastern end of the northern margin is a short distance north of the big bend of Koyukuk and Kateel rivers and the western end is a short distance north of the town of Candle on Kiwalik River in the northeastern corner of Seward Peninsula. On the east the region is bounded by a north and south line passing a little east of the junction of the Melozitna and Yukon rivers; on the west the best known point to which to refer the margin is the town of Council on Niukluk River. The area can be best comprehended by reference to the general map of northwestern Alaska (fig. 1), and to the more detailed maps, Plates I and V. For several reasons it has been decided to show the eastern part of this region separately from the western. This has been done mainly because better information has permitted mapping of the western portion on a scale of approximately 4 miles to the inch, whereas the eastern portion is shown on Plate V on a scale of approximately 16 miles to the inch. A division of this sort separates the great sand- stone shale area of the east from the more highly metamorphic areas of the west. In this report the eastern area, the one represented by 12 RECONNAISSANCE IN SEWARD PENINSULA AND Plate Y, will be referred to as the Nulato-Norton Bay region, and the western part (Pis. I, VI) will be called southeastern Seward Peninsula. HISTORY OF EXPLORATION. Prospectors and trappers have without doubt wandered over the region described in this report, but there is little or no record of their journeys and the facts that they learned have been lost. Other classes of travelers seldom ventured far from the main avenues of intercommunication; consequently, until within the last 10 or 15 years there have been few published references to any part of the Figure 1. — Sketch map of northwestern Alaska, showing location of region considered. region except the coast line, the Yukon and Ivoyukuk rivers, and the Kaltag portage. It is not intended at this place to give an account of all the exploring expeditions that have visited the waters sur- rounding Seward Peninsula, Norton Sound, and Bering Sea, and the reader who desires a more complete historical sketch is referred to the papers of Brooks 0 and Dall. ft The oldest settlement in this part of Alaska was at St. Michael, where, according to Dali, 0 Michael Tebenkoff, an officer in the Rus- “ Brooks, A. H., Geography and geology of Alaska : Prof. Paper U. S. Geol. Survey No. 45, 1906. 6 Dali, W. H., Alaska and its resources, Boston, 1870, 627 pp. and map. c Idem, p. 9. NORTON BAY-NULATO REGION, ALASKA. 13 sian- American Trading Company, established a post in 1833. From this point trading was carried on with the surrounding country. Soon other posts were established. Thus in 1838,® Malakoff, a creole, explored the Yukon as far north as the present town of Nulato and established a small settlement at the mouth of Nulato River. He left this post undefended during the winter of 1838-39 and it was de- stroyed by Indians. Soon afterward, in 1840, a trading post and fort were established on Norton Bay near the mouth of Unalaklik River and called by the name of the stream. This town, according to the 1900 census, had a population of 241. In spite of the destruction of the first settlement at the mouth of Nulato River the Russian- American Trading Company, appreciating the importance of this place as a point giving ready access to the Koyukuk basin, sent Derabin in 1841 to rebuild the fort. This was done, and in 1842 Lieutenant Zagoskin of the Russian navy visited the place. His visit is of interest because he made several short journeys into adjacent areas and published the results of his observa- tions. * & Although his accounts are fragmentary and imperfect, they show that he visited portions of Yukon River as far upstream as the mouth of the Melozitna, explored Koyukuk River as far as the mouth of the Kateel, and made a side trip up the Ivateel to assure himself that the native reports of an easy route into the Buckland drainage basin were correct. Unfortunately the maps published with his re- port are not based so much upon his direct personal observations as upon reports heard by him, and consequently many of the features are indicated only in a most general manner. In 1851 the trading post and fort at Nulato were burned and some of the inhabitants were massacred by Indians from the Koyukuk. When the town was rebuilt it was moved a mile or more up the river to its present location on a low gravel bench between Nulato Slough and Nulato River. About 1850 the great activity among many of the different nations, notably the English, in searching for the Franklin expedition re- sulted in several ships wintering in the waters of Kotzebue Sound. From these ships several exploring parties visited neighboring areas and added geographical data. Of these expeditions few prepared maps of sufficiently large scale to portray any but the most general features of the region explored. Among the overland trips were the exploration of Selawik Lake and vicinity by Surgeon Simpson of H. M. S. Plover , the trip from Chamisso Island by way of Buck- land and Koyuk rivers to St. Michael by Lieutenant Pirn of the same a Dali, W. H., Alaska and its resources, 1870, p. 48. 6 Zagoskin, L. A., Travels on foot and description of the Russian possessions in America from 1842 to 1844 : Ermans Archiv fur wissenschaftl. Kunde von Russland, vols. 6 and 7. 14 RECONNAISSANCE IN SEWARD PENINSULA AND ship, and the exploration of Buckland River by Captain Kellett and officers of H. M. S. Herald. Accounts of the voyages of the Herald ° show that the last-named expedition went up the Buckland for 30 miles (probably measured along the circuitous course of the river) in a whaleboat and then about 30 miles farther in lighter boats. The Pirn journey is also described in the same publication, but the narra- tive is more a recital of hardships than of geographic or geologic data and is not accompanied by a map. 6 A later impetus to exploration was given when in 1863 the Western Union Telegraph Company undertook to build a telegraph line through Alaska to connect the settled parts of America and Europe. In 1865 Kennicott, who was in charge of the scientific work of this company, crossed the Kaltag portage and surveyed the route to Nulato. During the same year J. T. Dyer and R. D. Potter, accord- ing to Dall, c made a very hazardous and successful exploration of the country between Norton Bay and the mouth of the Koyukuk River on the Yukon. Unfortunately no map of this trip was pub- lished, and the data collected, although undoubtedly used by Dall, d have never been available. In 1865, also, another party under the leadership of Baron von Bendeleben explored the route for the line from Norton Bay to Port Clarence, but the results like those of the other parties have never been published. The death of Kennicott in 1866 caused the leadership of the sci- entific corps to pass to W. H. Dali. It was the work accomplished while in charge of the telegraph exploration and during the year succeeding the abandonment of the enterprise that enabled Mr. Dali to write the most authoritative general book on Alaska that had appeared up to the time of the discovery of valuable gold deposits. All branches of geography and geology received some attention from this investigator and many of his observations will be quoted in more detail in subsequent portions of this report. A period of ten or fifteen years elapsed during which few notes of value were collected and published concerning the Nulato-Council region. In 1885 Lieutenant Allen made his famous trip, during which a portion of the Koyukuk was mapped and also the portage from Kaltag to Unalaklik. About this time explorations by the Revenue-Cutter Service were begun. The explorations of this branch of the government service which directly concerned the Nulato-Council region were by Purcell in the vicinity of Selawik Lake and by Zane along the Koyukuk to Nulato. ° Seeman, Berthold, Navigation of H. M. S. Herald during the years 1845-1851, vol. 2, London, 1853, pp. 119-120. b Op. cit., pp. 130-148. c Dali, W. H., Alaska and its resources, p. 357. d Op. cit., map. NORTON BAY-NULATO REGION, ALASKA. 15 In 1889 Prof. I. C. Russell ° ascended the Yukon, and his report of this trip furnished many facts, both of geologic and geographic significance. With the discovery of gold in the Klondike an influx of pros- pectors and others into Alaska followed, and soon afterwards the United States Geological Survey was able actively to undertake geo- graphic and geologic investigations of the district. One of the earliest of these surveys was conducted by Spurr, & mainly in the basin of the Kuskokwim. The geologic and topographic map pub- lished with his report covers the area between the Ivoyukuk and the Koyuk and from the mouth of the Kateel southward, and is con- sequently the first geologic map of the eastern half of the area studied in 1909. Most of the information concerning the Nulato-Council region was compiled or gathered from reports of prospectors, and very little geographic significance, outside of the distribution of the different geologic groups, was added. Schrader c in 1899 came clown the Ivoyukuk and the maps published in the report of his trip, which were made by T. G. Gerdine, afford a much more detailed representation of the region than had hitherto been available. No traverses of the country away from the river were made, so that details regarding the region between the Yukon and Norton Bay were not acquired. At the close of the field work in the Ivoyukuk region Schrader went to Nome and with Brooks made the first examination by Survey geologists of Seward Peninsula. In 1900 two main parties were dispatched to Seward Peninsula. One in charge of A. H. Brooks investigated the region as far east as Council ; the other in charge of W. J. Peters, with W. C. Menden- hall as geologist, investigated the southern part of the peninsula as far east as the Koyuk. The field studies of the Peters party cover the western part of the area visited by the expedition of 1909 and will be referred to in detail in succeeding pages of this report. In the main, however, the results may be summarized as follows: A delineation of the major features of the topography by maps, the publication of data on various geographic subjects such as climate, vegetation, and fauna, and the statement both verbal and graphic of the areal, historical, and economic geology.** The studies of Men- denhall were carried on mainly from the streams; the three larger ones, the Fish, the Tubutulik, and the Koyuk, he ascended in canoes. ° Russell, I. C., Notes on the surface geology of Alaska : Bull. Geol. Soc. America, vol. I, pp. 99-162. b Spurr, J. E., A reconnaissance in southwestern Alaska in 1898 : Twentieth Ann. Rept. U. S. Geol. Survey, pt. 7, 1909, pp. 31-264. c Schrader, F. C., Preliminary report on a reconnaissance along Chandlar and Koyukuk rivers. Alaska, in 1899 : Twenty-first Ann. Rept. U. S. Geol. Survey, pt. 2, 1900, pp. 441-486. d Mendenhall, W. C., A reconnaissance in the Norton Bay Region, Alaska, in 1900, a special publication of the U. S. Geol. Survey, 1901, pp. 183-222. 16 RECONNAISSANCE IN SEWARD PENINSULA AND During 1901 Schrader made a trip to northern Alaska and yisited portions of the Koyukuk drainage basin.® In the same year Menden- hall b explored the Kobuk River, and although this region lies con- siderably to the north of the Nulato-Council area the information secured throws considerable light on the problems of the latter. In the reconnaissance by Schrader, a geologic map was published show- ing the different formations along the Koyukuk northwestward from latitude 66° north, and this map and the notes on the lower part of the river already referred to on page 15 afford a continuous sec- tion from the Yukon northward. Of the other survey expeditions that have visited contiguous areas the party under Collier in 1902 and the Atwood party of 1907 are the only ones that require specific reference here. The main object of these expeditions was to study the coal resources of portions of Alaska. A publication has appeared setting forth the results of the investigations by Collier,® but Atwood’s report has not yet been published, though many of the manuscript notes have been kindly furnished to the present writers.** In 1906 a traverse from the mouth of the Koyukuk to the shores of Norton Sound and thence to Council was made by a party sent out by the War Department. The object of the survey was to determine the feasibility of a land route from the navigable waters of the Tanana to the vicinity of Council City. The maps accompanying the report of this survey were the first to give accurate information con- cerning a strip of country 5 to 10 miles wide extending from the mouth of Koyukuk to the mouth of the Ivoyuk, and are replete with facts of geographic interest. J. L. McPherson was in charge of the field work and prepared the text of the report.® Specimens of the various formations crossed were collected and submitted to the United States Geological Survey for study. On this account it was not neces- sary to cover the area surveyed by McPherson’s party again when the Nulato-Council region was visited in 1909. Reference to this report will be made in more detail in subsequent pages of this paper. In 1908 A. G. Maddren made an exploratory survey of Innoko River and contiguous areas. His report on this trip, with the accom- panying maps, affords considerable information concerning the « Schrader, F. C., Reconnaissance in northern Alaska in 1901 : Prof. Paper U. S. Geol. Survey No. 20, 1904, 139 pp. b Mendenhall, W. C., Reconnaissance from Fort Hamlin to Kotzebue Sound, Alaska : Prof. Paper U. S. Geol. Survey No. 10, 1901, 68 pp. « Collier, A. J., Coal resources of the Yukon, Alaska : Bull. U. S. Geol. Survey No. 218, 1903, 71 pp. d Atwood, W. W., Geology and mineral resources of parts of the Alaska Peninsula : Bull. U. S. Geol. Survey No. 467, in preparation. c McPherson, .T. L., Reconnaissance and survey for a land route from Fairbanks to Council City, Alaska : Sen. Doc. No. 214, 59th Cong., 2d sess., 1907, 22 pp., 7 maps, 6 plates. NORTON BAY-NULATO REGION, ALASKA. 17 country south of the Yukon. Practically all the features shown on Plate V south of the Yukon were taken directly from his maps." GENERAL TOPOGRAPHY. Throughout the Nulato- Council region the relief is relatively low. Few hills over 3,000 feet occur and the larger part of the upland area is only about 2,000 feet above sea level. Although there are no high ranges, steep slopes lead from the flat river bottoms to the high- lands. In the Nulato-Norton Bay region there are numerous parallel northeast-southwest ridges, the highest of which forms the divide between the Inglutalik-Ungalik and the Kateel-Gisasa river basins. The hills to the north of the East Fork of Koyuk River are low and rolling, without pronounced direction. Farther west, in Seward Pen- insula, there are three ranges forming prominent landmarks; these are the hills between Buckland and Kiwalik Rivers, and the Darby and the Bendeleben Mountains. The higher points of the first range rise to elevations of about 2,500 feet; in the Bendeleben Mountains the highest point is a little over 3,700 feet, and in the Darby Range the highest peak is about 3,000 feet. In the two last-named ranges precipitous slopes more than 2,000 feet high give a very rugged topography. Outside of these three higher areas the uplands are rolling, with elevations from 1,000 to 2,000 feet above sea level, unforested, well drained, and covered with angular fragments of frost-riven waste. Pinnacles of the underlying rocks form fantastic knobs here and there. The drainage of the region studied flows into the Yukon, into Nor- ton Bay, into Norton Sound, or into Kotzebue Sound. The streams belonging to the Yukon drainage and to the eastern part of Norton Bay show pronounced parallelism with the geological structure, and long, narrow valleys are the result. The gradients of the main valleys are low, but those of the small side streams rise rapidly headward. In places the streams flow through narrow rock-walled canyons of slight depth, but in others flat flood plains and gravel deposits occur. In the headward portions of the basins complex relations of the streams on opposite sides of the divide are noted, and it is by no means possible at long range to foretell the direction of the drainage. In Seward Peninsula, where the geologic structure is more complex, the effect on the streams is not well marked and irregular courses are the rule. In this part of the area the longer streams, such as the Koyuk, the Kiwalik, and the Tubutulik, flow more or less parallel " Maddren, A. G., The Innoko gold-placer district, Alaska : Bull. U. S. Geol. Survey No. 410, 1910, pis. I and II. 71469°* — Bull. 449—11 2 18 RECONNAISSANCE IN SEWARD PENINSULA AND with the mountains, but Fish River and its larger tributaries flow at right angles to the Bendeleben Range. Almost all the valleys show signs of having been eroded entirely by stream action. In the headwaters of the rivers rising in the Bendeleben and the Darby Ranges, however, there are glacial cirques and valleys. Here the present streams form irregular threads on the broadly open floors of valleys with very steep sides. At the mouths of the streams flowing into Norton Bay many of the streams, instead of showing erosion features, have filled the former valleys, which have been depressed, with sand and gravel. Examples of this kind of topography are found at the mouth of the Kwik, the Tubutulik, and the Kwiniuk Rivers, where numerous lakes and sloughs form an untraversable network during the summer. The coast line presents numerous examples of different types of shore topography. From the Reindeer Hills to the Koyuk a coastal plain, recently emerged, affords a relatively straight shore with such slight depths of water off the coast that approach for large vessels is impossible. Of course, under such conditions, harbors do not exist. On the western side of Norton Bay the sinking of the land and the attack of the waves have resulted in a rugged coast with cliffs and harbors. This part of the coast is formed by the Darby Range, which rises in abrupt slopes from the sea and forms a long southward pointing peninsula. West of this range the deep reentrant of Go- lofnin Sound and Bay, which probably represents the submerged portion of an old valley similar to that of Fish River, affords a good harbor. Still farther west rocky headlands w T ith intervening beaches produce a diversity of forms. On the depressed portions of the coast there are sand spits, such as the long point extending east from near the mouth of the Kwiniuk. DRAINAGE BASINS INCLUDED. All the streams flowing through the Nulato-Council region may be considered as belonging to one of three main basins, namely, the Yukon, the Norton Sound, and the Kotzebue Sound. Of these the first two include by far the greater number of streams. Roughly computed about 50 per cent of the area shown on the maps, Plates I and V, is drained by the Yukon and its tributaries, 45 per cent by tributaries to Norton Sound, and 5 per cent by streams flowing into Kotzebue Sound. In the description of these different basins no attempt will be made to enumerate all the streams belonging to each, for that sort of information may be better gathered from the maps (Pis. I and Y), but rather to present the particular features not easily legible on topographic maps of such scales as those adopted for publication. • NORTON BAY-NULATO REGION, ALASKA. 19 YUKON BASIN. The portion of the Yukon considered in this report extends from slightly east of the mouth of the Melozitna on the northeast to near the mouth of Ivaiyuh Slough on the southwest. In this distance the main tributaries are the Koyukuk, the Nulato, the Kaltag, and the Khotol. Regarding these various streams, with the exception of the first two, no new data of geographic interest were received during 1909, and as the facts already known about the Kaltag and the Khotol are indicated on the map accompanying these reports-, no further description of them will be attempted. Kateel and Gisasa rivers formed the portions of the Koyukuk drain- age that were visited and mapped, but only the upper 30 to 50 miles of each stream were seen in any detail. McPherson, who crossed the Gisasa near latitude 65° North, describes the valley as follows: 0 The Gisasa River is a stream from 70 to 150 feet wide, with gravelly bottom. Along the river banks on the north side of the valley is a heavy growth of spruce. Along the south side of the valley timber grows in scattered bunches, the intervening ground being to a considerable extent marshy and niggerhead tundra. From the survey of 1909 it was found that the Gisasa Basin was a peculiar, narrow one, lying between the Nulato on the southeast and the Kateel on the northwest. The river from mouth to head near Camp A9 must be nearly TO miles in a direct line. In this distance few or no tributaries much more than 10 miles in length are received. The basin is thus probably less than a score of miles wide in its widest part, and in the headward 50 miles it is generally much less. As will be shown in . a later portion of this report the direction and the general physical features of the Gisasa Valley are due to the geologic structure of the region, which trends northeast-southwest. Although in portions of its course! the river flows on a flat gravel plain essentially at the level of the stream, in other parts it has rock walls through which the stream has cut narrow canyons. These canyons are not continuous, but appear at irregular intervals along the valley. None of the canyons are deep, only a. few of the rock walls, if any of them, reaching a height of 50 feet. Above the steeply incised walls a more open valley is usually found, which indicates rather recent minor deformation of an anterior topography. The Kateel Basin was seen in less detail by the writers, but its general features are essentially similar to those of the Gisasa, except that its valley is wider and it has longer tributaries. From the survey of McPherson it was determined that Arvesta and Caribou creeks are tributaries of the Kateel. The former, where it was crossed, near latitude 65° north, is from 50 to 70 feet wide and from 1 to 3 feet deep. The latter is much smaller and runs at an elevation ° McPherson, J. L., op. cit., p. 17. 20 RECONNAISSANCE IN SEWARD PENINSULA AND about 500 feet higher. Prospectors who crossed the region somewhat north of McPherson’s route state that the volume of the Kateel is much smaller than that of the Gisasa, A general idea of the Kateel Basin was afforded by a view from Traverse Peak, though the weather was unfavorable for a thoroughly satisfactory observation of the topography. From this point it was evident that the northeasterly trend observed in the Gisasa Valley was still dominant. The divide along the western margin of the basin ran nearly north and south, so there is a considerable area tributary to this river. Low passes lead from the Kateel into the Ungalik, or into the Inglutalik, and probably into the Buckland. The pass from the Kateel to the Buckland was not actually seen, but enough of the drainage arrangement was evident to show that some of the western tributaries joining the Kateel below its junction with Arvesta Creek head in the low hills east of the Buckland, so that an easy route undoubtedly exists between the two rivers. The Nulato River Basin is long and narrow, being formed by two large streams occupying strike valleys that coalesce a few miles from the Yukon and below this point are transverse to the structure. The main branch is about 50 miles long in a straight line. Its valley has a broad gravel-filled floor on which the stream meanders in irregular pattern. It Avill be seen from the map of this valley that, although lying parallel with the Yukon and not more than 20 or at most 25 miles away from that stream, it drains northeastward, whereas the Yukon in that part of its course flows southwestward. This results in a more than right-angled turn near the mouth of the Nulato, and suggests that the physiographic development of the streams has been complex. Smooth slopes rise steeply from the valley floor to the relatively even uplands. On the southeastern side high hills scored by narrow gulches preserve the snowfall late in the summer. The volume of water carried by the main branch is therefore more con- stant throughout the season than is the case of those streams depend- ent upon the rainfall. Passes easily traversable by horses lead from the Nulato Basin to that of the Gisasa, of the Shaktolik, and prob- ably also of the Unalaklik. NORTON SOUND DRAINAGE. TRIBUTARIES OF NORTON SOUND EAST OF KOYUK RIVER. East of Koyuk River the main streams belonging to the Norton Sound drainage from south to north are the Unalaklik, the Shaktolik, the Ungalik, and the Inglutalik. All of these rivers show pro-^ nounced angular bends on a large scale, most of which are to be accounted for by the geologic structure of the region. This condi- tion is best illustrated by the three northern streams, whose basins are almost completely mapped. It will be seen from the map that NORTON BAY-NULATO REGION, ALASKA. 21 for the first 5 or 10 miles 8 in a straight line from the coast the rivers flow in winding courses at a right angle to the shore. Upstream from this point the course abruptly changes, and for the next 10 to 30 miles the rivers have a nearly north-south trend. Still farther up- stream the direction again changes, and the streams flow from the northeast or even from the east-northeast. Taken as a whole, the three rivers have narrow, rather contracted basins in the middle or north-south part of their courses, because few tributaries enter from the east and west ; in the upper part, however, because the main streams are flowing more or less across the geologic structure, the side streams are long and the area tributary to the main streams is therefore more extensive. Rock- walled canyons, separated from each other by gravel-filled basins, bear witness to recent crustal movements throughout the area. Unalaklik River was not visited by the survey party in 1909, but portions of it are well known, because the portage from the Yukon to St. Michael follows the lower part of this stream. A long branch joining from the north heads against the Shaktolik River, and it is probable that an easy pass across the hills to Nulato River exists. The northeast-southwest trend of the drainage and the intricacy of stream arrangements make it difficult to interpret the topography at long range. It is possible, therefore, that the Shaktolik may extend far- ther around the head of Nulato River than was evident at a distance, so that there may be more than one divide between Nulato and Unalaklik rivers. North of the Unalaklik is a rather small stream, the Iguik, which drains the triangular area between the Unalaklik and the Shaktolik. Its drainage basin is at most only a few hundred square miles in area. Although previously mapped as a rather unimportant river, the Shaktolik drains a considerable territory between the Ungalik on the north and the Unalaklik on the south. Its course is so irregular that it can with difficulty be recognized at any considerable distance. The Shaktolik was first seen in detail near camp A10. At this place its course was nearly due north, giving the impression that it flowed northward into the Ungalik. Near camp A13, however, it joined with a branch from the south and formed a good-sized stream. From the small increase in the size of the northern branch between camp A10 and its junction east of camp A13 it seems certain that only a few tributaries enter between these two places. Near camp A10 the river is incised in a narrow rock-walled canyon about 30 feet deep. Above the canyon walls the topography opens out into a broad older valley which had reached maturity before the uplift took place by which the present cycle was started. The floor ° The figures given represent measurements in an air-line and not along the circuitous courses of the streams. 22 RECONNAISSANCE IN SEWARD PENINSULA AND of this older valley is in large measure rock cut with a relatively small amount of gravel covering. Well-rounded material, however, is practically universally present and affords indisputable proof of the presence of stream erosin at this higher level. Near camp A13 the canyon-like character is wanting. Four or 5 miles below camp A14 incised meanders, with radii of from one-half mile to 1 mile, occur. Here the walls are, for the most part, gravel, with the bed- rock not exposed. It is believed that the differences in the amount of filling and incision noted along this stream are due to the undula- tory character of the most recent uplift. No accurate determinations were made of the volume of the Shak- tolik, but from float measurements near camp A12 it was found that the. discharge was between 150 and 200 second-feet. The tributary from the north joining east of camp A13 was of about equal vol- ume, and below camp All the amount of water had increased to such an extent that the stream could be crossed only with difficulty. In this connection it should be noted that 1909 was an exceptionally dry season, so that a greater volume is to be expected during a year of normal precipitation. Ungalik River shows the same characters as the other streams tributary to Norton Bay from the east. Its basin shows the three distinct parts previously referred to, namely, an open east and west course through the coastal plain province, a narrow north and south portion parallel to the geological structure of the region, and a northeast and east-northeast course in the headward portion. In this upper part the basin shows the same feature previously noted on the Shaktolik, namely, that the tributaries from the south are longer than those from the north, so that the basin, if the main stream be considered as its axis, is decidedly unsymmetrical. This lack of symmetry seems to be due to three causes, namely, structural con- trol, climatic conditions, and tilting. Asymmetrical valleys are common in Alaska, and have previously been described by different authors. An epitome of the various causes with reference to a spe- cific region has been published by Goodrich. 0 It was pointed out by this geologist that the effect of insolation differs according to the condition of the stream as to load ; thus, if the stream is overloaded, the tendency will be for the waste to push the stream toward the side receiving the least sun, whereas, if the stream is not carrying all the material it can the reverse tendency will dominate, and the stream will migrate toward the side receiving the most sun. Plate II, A , shows one of the tributaries of the Shaktolik below camp A12, which is migrating toward the north because the stream is under- loaded and the south-facing slope receives more warmth than the ° Goodrich, H. B., Cause of asymmetry of streams : Eighteenth Ann. Kept. U. S. Geol. Survey, pt. 3, 1898, pp. 285-289. U. S. GEOLOGICAL SURVEY BULLETIN 449 PLATE II B. UPLANDS BETWEEN EAST FORK AND INGLUT ALIK RIVER. NORTON BAY-NULATO REGION, ALASKA. 23 other. In a consideration of the development of the drainage it should be borne in mind that types due to one cause alone are prac- tically absent and that complexity of origin, rather than simplicity, is normal. From Ungalik River passes may be found into the Inglutalik to the north or to the Kateel on the east, or into the Shaktolik on the south. None of these passes are over 3,000 feet above the sea, and many could be found at elevations below 2,500 feet. The saddle by which McPherson crossed from the Kateel to the Ungalik was only a little over 2,000 feet. As regards size, the Ungalik is not so large as the Shaktolik. Two miles below camp A1G the stream could be crossed in less than 2 feet of water, and farther upstream it was still shallower except for occasional deep holes. Lower downstream, however, in the coastal plain portion of its course, it becomes deeper and sluggish, and in- stead of a hard grav- elly bottom it has a soft mud bottom that makes crossing difficult with- out a boat. Inglutalik River de- rives its name from the Eskimo words meaning u river of bones,” in ref- erence to the number of mastodon and other „ , V/ZrJtJk Relatively weak rocl