M

Professional Paper No. 52 (M / B> Desoriptive Geology, 89 

0, Underground Waters, 65

DEPARTMENT OF THE INTERIOR 

UNITED STATES GEOLOGICAL SURVEY

CHARLES D. WALCOTT, DIRECTOR

GEOLOGY AND UNDERGROUND WATERS

OF THE

ARKANSAS VALLEY IN EASTERN COLORADO

BY

, 2ST-. HWASHINGTON

GOVERNMENT PRINTING OFFICE 

1906
M

Professional Paper No. 52 (M / B> Desoriptive Geology, 89 

0, Underground Waters, 65

DEPARTMENT OF THE INTERIOR 

UNITED STATES GEOLOGICAL SURVEY

CHARLES D. WALCOTT, DIRECTOR

GEOLOGY AND UNDERGROUND WATERS

OF THE

ARKANSAS VALLEY IN EASTERN COLORADO

BY

, 2ST-. HWASHINGTON

GOVERNMENT PRINTING OFFICE 

1906
CLASSIFICATION OF THE PUBLICATIONS OF THE UNITED STATES GEOLOGICAL SURVEY.

[Professional Paper No. 52.]

The serial publications of the United States Geological Survej' consist, of (1) Annual Reports, 

(2) Monographs, (3) Professional Papers, (4) Bulletins, (5) Mineral Resources, (6) Water-Supply 

and Irrigation Papers, (7) Topographic Atlas of the United States folios and separate sheets thereof, 

(8) Geologic Atlas of the United States folios thereof. The classes numbered 2, 7, and 8 are sold 

at cost of publication; the others are distributed free. A circular giving complete lists may be had 

on application. ,

Most of the above publications may be obtained or consulted in the following ways:

1. A limited number are delivered to the Director of the Survey, from whom they may be 

obtained, free of charge (except classes 2, 7, and 8), on application.

2. A certain number are allotted every Member of Congress, from whom they may be obtained, 

free of charge, on application.

3. Other copies are deposited with the Superintendent of Documents, Washington, D. C^, from 

whom they may be had at practically cost.

4. Copies of all Government publications are furnished to the principal public libraries in the 

large cities throughout the United States, where they may be consulted by those interested.

The Professional Papers, Bulletins, and Water-Supply Papers treat of a variety of subjects, and 

the total number issued is large. They have therefore been classified into the following series: A, 

Economic geology; B, Descriptive geology; C, Systematic geology and paleontology; D, Petrography 

and mineralogy; E, Chemistry and physics; F, Geography; G, Miscellaneous; H, Forestry; I, Irriga-' 

tion; J, Water storage; K, Pumping water; L, Quality of water; M, General hydrographic investiga-

 \ tions; N, Water-power; 0, Underground waters; P, Hydrographic progress reports. This paper 

is the eighty-ninth in Series B, and the fifty-fifth in Series O, the complete lista of which follow. 

(PP=Professional Paper, B=Bulletin, WS=Water-Supply Paper.)

SERIES B, DESCRIPTIVE GEOLOGY.

B 23. Observations on the junction between the Eastern sandstone and the Keweenaw series on Keweenaw Point, Lake 

Superior, by R. D. Irving and T. C. Chamberlin. 1885. 124 pp., 17 pis. (Out of stock.)

B 33. Notes on geology of northern California, by J. S. Diller. 1886. 23pp. (Out of stock.)

B 39. The upper beaches and deltas of Glacial Lake Agassiz, by Warren Upham. 1887. 84pp., 1 pi. (Out of stock.)

B 40. Changes in river courses in Washington Territory due to glaciation, by Bailey Willis. 1887. 10 pp., 4 pis. (Out of 

stock.)

B 45. The present condition of knowledge of the geology of Texas, by R. T. Hill. 1887. 94 pp. (Out of stock.)

B 53. The geology of Nantucket, by N. S. Shaler. 1889. 55 pp., 10 pis. (Out of stock.) ,

B 57. A geological reconnaissance in southwestern Kansas, by Robert Hay. 1890. 49 pp., 2 pis.

B 58. The glacial boundary in western Pennsylvania, Ohio, Kentucky, Indiana, and Illinois, by G. F. Wright, with introduction by T. C. Chamberlin. 1890. 112 pp., 8 pis. (Out of stock.)

B 67. The relations of the traps of the Newark system in the New Jersey region, by N. H. Carton. 1890. 82 pp. (Out of 

stock.)

B 104. Glaciation of the Yellowstone Valley north of the Park, by W. H. Weed. 189S. 41 pp., 4 pis.

B 108. A geological reconnaissance in central Washington, by I. C. Russell. 1S93. 108 pp., 12 pis. (Out of stock.)

B 119. A geological reconnaissance in northwest Wyoming, by G. H. Eldridge. 1894. 72 pp., 4 pis.

B 137. The geology of the Fort Riley Military Reservation and vicinity, Kansas, by Robert Hay. 1896. 35 pp., 8 pis.

B 144. The moraines of the Missouri Coteau and their attendant deposits, by J. E. Todd. 1896. 71 pp., 21 pis.

B 158. The moraines of southeastern South Dakota and their attendant deposits, by J. E. Todd. 1899. 171 pp., 27 pis.

B 159. The geology of eastern Berkshire County, Massachusetts, by B. K. Emerson. 1899. 139 pp., 9 pis.

B 165. Contributions to the geology of Maine, by H. S. Williams and H. E. Gregory. 1900. 212 pp., 14 pis.

I
II SERIES LIST.

WS 70. Geology and water resources of the Patrick and Goshen Hole quadrangles in eastern Wyoming and western

Nebraska, by G. I. Adams. 1902. 50 pp., 11 pis.

B 199. Geology and water resources of the Snake River Plains of Idaho, by I. C. Russell. 1902. 192 pp., 25 pis. 

PP1. Preliminary report on the Ketchikan mining district, Alaska, with an introductory sketch of the geology of southeastern Alaska, by A. H. Brooks. 1902. 120 pp., 2 pis.

PP 2. Reconnaissance of the northwestern portion of Scward Peninsula, Alaska, by A. J. Collier. 1902. 70 pp., 11 pis. 

PP 3. Geology and petrography of Crater Lake National Park, by J. S. Diller and H. B. Patton. 1902. 167 pp., 19 pis. 

PP 10. Reconnaissance from Fort Hamlin to Kotzebue Sound, Alaska, by way of Ball, Kanuti, Alien, and Kowak rivers,

by W. C. Mendenhall. 1902. 68 pp., 10 pis.

PP 11. Clays of the United States east of the Mississippi River, by Heinrich Ries. 1903. 298 pp., 9 pis. 

PP 12. Geology of the Globe copper district, Arizona, by F. L. Ransome. 1903. 168 pp., 27 pis. 

PP 13. Drainage modifications in southeastern Ohio and adjacent parts of West Virginia and Kentucky, by W. G. Tight.

1903. Ill pp., 17 pis. 

B 208. Descriptive geology of Nevada south of the fortieth parallel and adjacent portions of California, by J. E. Spurr.

1903. 229 pp., 8 pis. ,

B 209. Geology of Ascutney Mountain, Vermont, by R. A. Daly. 1903. 122 pp., 7 pis. 

WS 78. Preliminary report on artesian basins in southwestern Idaho and southeastern Oregon, by I. C. Russell. 1903.

51 pp., 2 pis. 

PP 15. Mineral resources of the Mount Wmngell district, Alaska, by W. C. Mendenhall and F. C. Schrader. 1903. 71 pp.,

10 pis. 

PP 17. Preliminary report on the geology and water resources of Nebraska west of the one hundred and third meridian,

by N. H. Darton. 1903. 69 pp., 43 pis. s 

B 217. Notes on the.geology of southwestern Idaho and southeastern Oregon, by I. C. Russell. 1903. 83 pp., 18 pis. 

B 219. The ore deposits of Tonopah, Nevada (preliminary report), by J. E. Spurr. 1903. 31 pp., 1 pi. ' 

PP20. A reconnaissance in northern Alaska in 1901, by F. C. Schrader. 1904. 139 pp., 16 pis.

PP21. The geology and ore deposits of the Bisbee quadrangle, Arizona, by F. L. Ransome. 1904. 168pp., 29 pis. 

WS 90. Geology and water resources of part of the lower James River Valley, South Dakota, by J. E. Todd and C. M. Hall.

1904. 47 pp., 23 pis.

PP 25. The copper deposits of the Encampment district, Wyoming, by A. C. Spencer. 1904. 107 pp., 2 pis. 

PP 26. Economic resources of the northern Black Hills, by J. D. Irving, with contributions by S. F. Emmons and T. A.

Jaggar, jr. 1904. 222.pp., 20 pis. 

PP 27. A geological reconnaissance across the Bitterroot Range and Clearwater Mountains in Montana and Idaho, by

Waldemar Lindgren. 1904. 122 pp., 15 pis. 

PP 81. Preliminary report on the geology of the Arbuckle and Wichita mountains in Indian Territory and- Oklahoma,

by J. A. Taff, with an appendix on reported ore deposits in the Wichita Mountains, by H. F. Bain. 1904. 97 pp.,

8 pis. 

B 235. A geological reconnaissance across the Cascade Range near the forty-ninth parallel, by G. O. Smith and F. C.

Calkins. 1904. 103 pp., 4 pis.

B 236. The Porcupine placer district, Alaska, by C. W. Wright. 1904. 35 pp., 10 pis. 

B 237. Igneous rocks of the Highwood Mountains, Montana, by L. V. Pirsson. 1904. 208 pp., 7 pis. 

B 238. Economic geology of the tola quadrangle, Kansas, by G. I. Adams, Erasmus Ha worth, and ,W. R. Crane. 1904.

83pp., Ipl.

PP 32. Geology and underground water resources of the central Great Plains, by N. H. Darton. 1905. 433 pp., 72 pis. 

WS 110. Contributions to hydrology of eastern United States, 1904; M. L. Fuller, geologist in charge. 1905. 211 pp., 5 pis. 

B 242. Geology of the Hudson Valley between the Hoosic and the Kinderhook, by T. N. Dale. 1904. 63 pp., 3 pis. 

PP 84. The Delavan lobe of the Lake Michigan Glacier of the Wisconsin stage of glaciation and associated phenomena, by

W. C. Alden. 1904. 106 pp., 15 pis.

PP 35. Geology of the Perry Basin in southeastern Maine, by G. O. Smith and David White. 1905. 107 pp., 6 pis. 

B 243. Cement materials and industry of the United States, by K. C. Eckel. 1905. 395 pp., 15 pis. 

B 246. Zinc and lead deposits of northeastern Illinois, by H. F. Bain. 1904. 56 pp., 5 pis. 

B 247. The Fairhaven gold placers of Seward Peninsula, Alaska, by F. H. MofHt. 1905. 85 pp., 14 pis. 

B 249. Limestones of southwestern Pennsylvania, by F. G. Clapp. 1905. 52 pp., 7 pis. 

B 250. The petroleum fields of the Pacific coast of Alaska, with an account of the Bering River coal deposit, by G. C.

Martin. 1905. 65 pp., 7 pis. t 

B 251.- The gold placers of the Fortymile, Birch Creek, and Fairbanks regions, Alaska, by L. M. Prindle. 1905. 64 pp.

16 pis.

WS. 118. Geology and water resources of a portion of east-central Washington, by F. C. Calkins. 1905. 96 pp., 4 pis. 

B 252. Preliminary report on the geology and water resources of central Oregon, by I. C. Russell. 1905. 138 pp., 24 pis. 

-PP36. The lead, zinc, and fluorspar deposits of western Kentucky, by-E. O. Ulrich and W. S. Tangier Smith. 1905.

218pp., 15 pis. 

PP 38. Economic geology of the Bingham mining district of Utah, by J. M. Boutwell, with a chapter on areal geology, by

Arthur Keith, and an introduction on general geology, by S. F. Emmons. 1905. 413 pp., 49 pis. 

PP 41. The geology of the central Copper River region, Alaska, by W. C. Mendenhall. 1905. 133 pp., 20 pis. 

B 254. Report of progress in the geological resurvey of the Cripple Creek district, Colorado, by Waldemar Lindgren and

F. L. Ransome. 1904. 36 pp.

B 255. The fluorspar deposits of southern Illinois, by H. Foster Bain. 1905. 75 pp., 6 pis. 

B 256. Mineral resources of the Elders Ridge quadrangle, Pennsylvania, by R. W. Stone. 1905. 85 pp., 12 pis. 

B 257. Geology and paleontology of the Judith River beds, by T. W. Stanton and J. B. Hatcher, with a chapter on the

fossil plants, by F. H. Knowlton. 1905. 174 pp., 19 pis.
SERIES LIST. Ill

PP 42. Geology of the Tonopah mining district, Nevada, by J. E. Spurr. 1905 295 pp., 24 pis.

WS 123. Geology and underground water conditions of the Jomada del Muerto, New Mexico, by C. E. Keyes. 1905.

42 pp., 9 pis.

WS 136. Underground waters of Salt River Valley, Arizona, by W. T. Lee. 1905. 194 pp., 24 pis. 

PP 4B. The copper deposits of Clifton-Morenci, Arizona, by Waldemar Lindgren. 1905. ' 375 pp., 25 pis. 

B 265. Geology of the Boulder district, Colorado, by N. SI. Fenneman. 1905. 101 pp., 5 pis. 

B 267. The copper deposits of Missouri, by H. F. Bain and E. O. Ulrich. 1905. 52.pp., 1 pi.

PP 44. Underground water resources of Long Island, New York, by A. C. Veatch and others. 1905. 394 pp., 34 pis. 

WS 148. Geology and water resoure.-s of Oklahoma, by C. N. Gould. 1905. 178 pp., 22 pis. 

B 270. The configuration of the rock floor of Greater New York, by W. H. Hobbs. 1905. 96 pp., 5 pis. 

B 272. Taconic physiography, by T. M. Dale. 1905. 52 pp., 14 pis. 

PP 45. The geography and geology of Alaska, a summary of existing knowledge, by A. H. Brooks, with a section on climate,

by Cleveland Abbe, jr., and a topographic map and description thereof, by R.M. Goode. 1905. 327 pp., 34 pis. 

B 273. The drumlins of southeastern Wisconsin (preliminary paper), by W.C. Alden. 1905. 46 pp., 9 pis. 

PP 46. Geology and underground water resources of northern Louisiana and southern Arkansas, by A. C. Veatch. 1906,

 pp., 51 pis. 

PP 49. Geology and mineral resources of part of the Cumberland Gap coal field, Kentucky, by G. H. Ashley and L. C. Glenn,

in cooperation with the State Geological Departmentof Kentucky, C. J. Norwood, curator. 1906. 239 pp., 40 pis, 

PP 50. The Montana lobe of the Keewatin ice sheet, by F. H. H. Calhoun. 1906. 62 pp., 7 pis. 

B. 277. Mineral resources of Kenai Peninsula, Alaska: Gold fields of the Turnagain Arm region, by F. H. Mofflt, and the

coal fields of Kachemak Bay region, by R. W. Stone, 1906. 80 pp., 18 pis. 

WS 154. The geology and water resources of the eastern portion of the Panhandle of Texas, by C. N. Gould. 1906.

64 pp.,.15 pis.

B 278. Geology and coal resources of the Cape Lisburne region, Alaska, by A. J. Collier. 1906. 54 pp., 9 pis. 

B 279. Mineral resources of the Kittanning and Rural Valley quadrangles, Pennsylvania, by Charles Butts. 1906. pp.

11 pis.

B 280. The Rampart gold placer region, Alaska, by L. M. Prindle and F. L. Hess. 1906. 54 pp., 7 pis. 

B 282. Oil fields of the Texas-Louisiana Gulf coastal plain, by N. M. Fenneman. 1906. 146 pp., 11 pis. WS 157. Underground water in the valleys of Utah Lake and Jordan River, Utah, by G. B. Richardson. 1906. 81 pp., 9 pis. 

PP 51. Geology of the Bighorn Mountains, by N. H. Darton. 1906. 129 pp., 47 pis. 

WS 158. Preliminary report on the geology and underground waters of the Roswell artesian area, New Mexico, by C. A.

Fisher. 1906. 29 pp., 9 pis. 

PP 52. Geology and underground waters of the Arkansas Valley in eastern Colorado, by N. H. Darton. 1906. 90 pp., 28 pis.

SERIES O, UNDERGROUND WATERS. '

WS 4. A reconnaissance in southeastern Washington, by I. C. Russell. 1897. 96 pp., 7 pis. (Out of stock.)

WS 6. Underground waters of southwestern Kansas, by Erasmus Haworth. 1897. 65 pp., 12 pis. (Out of stock.)

WS 7. Seepage waters of northern Utah, by Samuel Fortier. 1897. 50 pp., 3 pis. (Out of stock.)

WS 12. Underground waters of southeastern Nebraska, by N. H. Darton. 1898. 56 pp., 21 pis. (Out of stock.)

WS 21. Wells of northern Indiana, by Frank Leverett. 1899. 82 pp., 2 pis. (Out of stock.)

WS 26. Wells of southern Indiana (continuation of No. 21), by Frank Leverett. 1899. 64pp. (Out of stock.)

WS 30. Water resources of the Lower Peninsula of Michigan, by A. C. Lane. 1899. 97 pp.,7 pis. (Out of stock.)

WS 31. Lower Michigan mineral waters, by A. C. Lane. 1899. 97pp., 4 pis. (Out of stock.)

WS 34. Geology and water resources of a portion of southeastern South Dakota, by J. E. Todd. 1900. 34 pp., 19 pis.

WS 53. Geology and water resources of Nez Perces County, Idaho, Pt. I, by I. C. Russell. 1901. 86 pp., 10 pis.

WS 54. Geology and water resources of Nez Perces County, Idaho, Pt. II, by I. C. Russell. 1901. 87-141 pp.

WS 55. Geology and water resources of a portion of Yakima County, Wash., by G. O. Smith. 1901. 68 pp., 7 pis.

WS 57. Preliminary list of deep borings in the United States, Pt. I, by N. H. Darton. 1902.' 60pp. (Out of stock.)

WS 59. Development and application of water in southern California, Pt. I, by J. B. Lippincott. 1902. 95pp.,11 pis. (Out

of stock.) 

WS 60. Development and application of water in southern California, Pt II, by J. B. Lippincott. 1902. 96-140 pp. (Out of

stock.)

WS 61. Preliminary list of deep borings in the United States, Pt. II, by N. H. Darton. 1902. 67pp. (Out of stock.) 

WS 67. The motions of underground waters, by C. S. Slichter. 1902. 106 pp., 8 pis.

B 199. Geology and water resources of the Snake River Plains of Idaho, by I. C. Russell. 1902. 192 pp., 25 pis. 

WS 77. Water resources of Molokai, Hawaiian Islands, by Waldemar Lindgren. 1903. 62 pp., 4 pis. 

WS 78. Preliminary report on artesian basins in southwestern Idaho and southeastern Oregon, by I. C. Russell. 1903.

53 pp. ,2 pis. 

PP 17. Preliminary report on the geology and water resources of Nebraska west of the one hundred and third meridian,

by N: H. Darton. 1903. 69 pp., 43 pis. 

WS 90. Geologyand water resources of a part of the lower James River Valley, South Dakota, by J.E. Toddand C. SI. Hall.

1904. 47 pp., 23 pis. 

WS 101. Underground waters of southern Louisiana, by G. D. Harris; with discussions of their uses for water supplies and

for rice irrigation, by SI. L. Fuller. 1904. 98 pp., 11 pis.

WS 102. Contributions to the hydrology of eastern United States, 1903, by M. L. Fuller. 1904. 522 pp. 

WS 104. Underground waters of Gila Valley, Arizona, by W. T. Lee. 1904. 71 pp., 5 pis. 

WS110. Contributions to the hydrology of eastern United States, 1904; M. L. Fuller, geologist in charge. 1904. 211 pp., 5 pis.
IV SERIES LIST.

PP 32. Geology and underground water resources of the central Great Plains, by N.H. Barton. 1904. 433pp., 72 pis. (Out

of stock.)

\VS 111. Preliminary report on underground waters of Washington, by Henry Landes. 1904. 85 pp., 1 pi. 

WS 112. Underflow tests in the drainage basin of Los Angeles River, by Homer Hamlin. 1904. 55 pp., 7 pis. 

\VS 114. Underground waters of eastern United States', by M. L. Fuller, geologist in charge. 1904. 285 pp., 18 pis. 

WS 118. Geology and water resources of east-central Washington, by F. C. Calkins. 1905. 96 pp., 4 pis. 

B 252. Preliminary report on the geology and water resources of central Oregon, by 1. C. Russell. 1905. 138 pp., 24 pis. 

\VS 120. Bibliographic review and index of papers relating to underground waters published by the United States Geological Survey, 1879-1904, by M. L. Fuller. 1905. 128 pp.

WS 122. Relation of the law to underground waters, by D. W. Johnson. 1905. 65 pp. 

WS 123. Geology and underground water conditions of the Jornada del Muerto, New Mexico, by C. R. Keyes. 1905. 42 p.p.

9 pis.

WS 136. Underground waters of the Salt River Valley, by W. T. Lee. 1905. 194 pp., 24 pis. 

B 264. Record of deep-well drilling for 1904, by M. L. Fuller, E. F. Lines, and A. C. Veatch. 1905. 106 pp. 

PP 44. Underground water resources of Long Island, New York, by A. C. Veatch and others. 1905. 394 pp., 34 pis. 

WS 137. Development of underground waters in the eastern coastal plain region of southern California, by W. C. Mendenhall. 1905. 140 pp., 7 pis. 

WS 138. Development of underground waters in the central coastal plain region of southern California, by W. C. Mendenhall. 1905. 162 pp., 5 pis. 

WS 139. Development of underground waters in the western coastal plain region of southern California, by W. C. Mendenhall. 1905. 105 pp., 7 pis.

WS 140. Field measurements of tbe rate of movement of underground waters, by C. S. Slichter. 1905. 122 pp., 15 pis. 

WS 141. Observations on the ground waters of Rio Grande Valley, by C. S. Slichter. 1905. 83 pp., 5 pis. 

WS 142. Hydrology of San Bernardino Valley, California, by W. C. Mendenhall. 1905. 124 pp., 13 pis. 

WS 145. Contributions to the hydrology of eastern United States; M. L. Fuller, geologist in charge. 1905. 220 pp., 6 pis. 

WS 148. Geojogy and water resources of Oklahoma, by' C. N. Gould. 1905. 178 pp., 22 pis. 

WS 149. Preliminary list of deep borings in the United States, second 'edition, with additions, by N. H. Barton. 1905.

175pp.

PP 46. Geology and underground water resources of northern Louisiana and southern Arkansas, by A. C. Veatch. 1906. 

WS 153. The underflow in Arkansas Valley in western Kansas, by C. S. Slichter. 1906. 90 pp, 3 pis. 

WS 154. The geology and water resources of the eastern portion of the Panhandle of Texas, by C. N. Gould. 1906. 64 pp.,

15 pis.

WS 165. Fluctuations of the water level in wells, with special reference to Long Island, New York, by A. C. Veatch. 1906. 

WS 157. Underground water in the valleys of Utah Lake and Jordan River, Utah, by G. B.Richardson. 1906. 81pp., 9 pis. 

WS 158. Preliminary report on the geology and underground waters of the Roswell artesian area, New Mexico, by C. A.

Fisher. 1906. 29 pp., 9 pis.

PP 52. Geology and underground waters of Arkansas Valley in eastern Colorado, by N. H. Barton. 1906. 90 pp., 28 pis. 

The following papers also relate to this subject: Underground waters of Arkansas Valley in eastern Colorado, by G. K. 

Gilbert, in Seventeenth Annual, 'Pt. II; Preliminary report on artesian waters of a portion of the Bakotes, by N. H. Darton, 

in Seventeenth Annual, Pt. II; Water resources of Illinois, by Frank Leverett, in Seventeenth Annual, Pt. II; Water 

resources of Indiana and Ohio, by Frank Leverett, in Eighteenth Annual, Pt. IV; New developments in well boring and 

Irrigation in eastern South Bakota, by N. H. Darton, in Eighteenth Annual, Pt. IV; Rock waters of Ohio, by Edward 

Orton, in Nineteenth Annual, Pt. IV; Artesian well prospects in the Atlantic coastal plain region, by N. H. Darton, 

Bulletin No. 138.

Correspondence should be addressed to

THE DIRECTOR,

UNITED STATES GEOLOGICAL SURVEY, 

JULY, 1906. WASHINGTON, D. C:

o
CONTENTS.

Page.

Introduction............................................................................... 7

General configuration of the region............................................................ 8

General geology of eastern Colorado._....v __........_-_.-.........__........._......._....._._. .9

General relations........................................................................ 9

Structure. .............................................................................. 9

Formations............................................................................ 10

ieelogy of the Arkansas Valley region......................................................... 12

Stratigraphy........................................................................... 12

Cambrian system................................................................... 13

Ordovician system. .................................................................. 14

Manitou limestone.............................................................. 14

Harding sandstone. ..j........................................................... 14

Fremont limestone.............................................................. 14

Carboniferous and Triassic(l) systems................................................. 15

Millsap limestone. ............................................................... 15

"Red Beds"................................................................... 16

Cretaceous system.................................................................. 21

Morrison formation.............................................................. 21

Comanche series................................'................:............... 25

"Dakota" sandstone............................................................ 25

Graneros shale.................................................................. 27

Greenhorn limestone .............................A.............................. 27

Carlile formation................................................................ 28

Timpas limestone............................................................... 28

Apishapa formation............................................................... '29

Pierre shale...................--.............'.................................. 30

Fox Hills sandstone..................................'.........................,. 32

Laramie formation.............................................................. 32

Cretaceous (1) system .............................................................. 33

Arapahoe formation............-.--..-..-..-..-.....-.....-..................._, 33

Poison Canyon formation........................................................ 33

Denver formation............................................................... 34

Cuchara formation............................................................... 34

Tertiary system..................................................................... .34

Monument Creek formation...................................................... 34

Nussbaum formation............................................................ 34

Quaternary system.................................................................. 35

Alluvium...................................................................... 35

Dune sands. ---.....-...--.-...-.--..-.-.-.---...-......-.........-.-...-.-.... 35

Igneous rocks.......---.-.---....---...---.-.---------.--.-.-.-.-.-.-.-.-...-.-..-..... 35

Manitou embayment.................................................................... 36

Canyon embayment-.................................................................... 38

General structure................................................................... 38

Garden Park area.................................................................... 39

West of Canyon.................................................................... 40

3
4 CONTENTS.

Geology of the Arkansas Valley region Continued. Page

East side of Greenhorn Mountain......................................................... 43

 Geologic history........................................................................ 45

Cambrian._'.._._......_._....._......_..._...._._....._..._......._..._.__..._. 45

Ordovician..................................................................... 46

Silurian-Devonian............................................................... 46

Carboniferous.................................................................. 46

Cretaceous..................................................................... 47

Post-Laramie conditions ........................................................ 49

Quaternary.................................................................... 50

Underground waters.......................................................................... 50

"Dakota" sandstone waters.............................................................. 50

General conditions................................................................:. 50

Flowing wells...................................................................... '52

Nonflowiiig deep wells ................'.............................................. 62

Unsuccessful deep borings...............................................'.............' 68

Source of the "Dakota" water........................................................ 73

Depths to the "Dakota" sandstone..................................................... 74

Area of flow...-...............................................-............_....... 75

Pressure or head..........................'.......................................... 76

Quantity-. ....................................^............^ ....................... 77

QuaMty............................................................................ 79

Waters of the "Red Beds" and the Morrison formation....... ........j...................... 82

Waters of the Laramie and associated formations........................................... 83

Waters of the later Tertiary deposits...................................................... 84

Waters in the dune sands................................................................ 84

Index ................-........-....--...-.--.-.-..-.---..----...-.-:...--.-...----.--.... 85

ILLUSTRATIONS.

v Page. 

PLATE I. Map of central-western United States, showing area treated in this report............... 7

. II. Relief map of the drainage basin of Arkansas River in Colorado........................ 8

III. A, The High Plains in eastern Colorado; B, view on the Great Plains in eastern Colorado.. 8

IV. A, Haystack Butte, Pueblo County, Colo.; B, Apisli^pa Canyon northwest of Thatcher,

Colo.......................................................................... 10

V. A, "Dakota" hogback at Canyon, Colo.; B, "Dakota" hogback ridge southwest of Canyon, Colo..................................................................... 12

VI. Geologic map of the Arkansas Valley in southeastern Colorado ....................... Pocket.

VII. Geologic sections across southeastern Colorado...................................... 14

VIII. A, Quarry in Harding sandstone northwest of Canyon, Colo.; B, Fremont limestone northwest of Canyon, Colo........................................................... 16

I.. A, Vertical lower "Red Beds," Garden of the Gods, Colo.; B, the stone wall on Purgatory

River west of Trinidad, Colo.........................................'.......-..- 18

X. A, "Dakota" sandstone in hogback ridge southwest of Canyon, Colo.; B, bone-bearing

sandstone in middle Morrison formation in Garden Park north of Canyon, Colo ........ 22

XI. A and B, The stone wall on Purgatory River west of Trinidad, Colo ................... 24

XII. A, Greenhorn limestone near Thatcher, Colo.; B, Timpas limestone in quarry southeast of

La Junta, Colo................................................ 5 ................ 26

XIII. Characteristic fossils of Niobrara and Greenhorn limestones ......-.-....---.......---. 28

XIV. View along Arkansas River; basal Timcas limestone on Carlile sandstone....-....-.....- 30
ILLUSTRATIONS. 5

Page. 

PLATE XV. A, Tepee buttes in Pierre shale north of Nepesta, Colo.; B, Timpas limestone on Carlile

sandstone northwest of La Junta, Colo............................................ 32

' XVI. Map and cross sections showing geologic relations in the Manitou embayment and northward. ........................................................................ 36

XVII. A, Vertical "Red Beds" near Colorado City, Colo.; B, Morrison formation on granites near .

Grape Creek, southwest of Canyon, Colo.......................................... 38

XVIII. Map and cross sections of "Dakota" and associated formations in the Canyon embayment,

Colo.........................................;................................ 40

XIX. A, Shale member lying between base of Fremont limestone and top of Harding sandstone on mountain slope northwest of Canyon, Colo.; B, Harding sandstone on gneiss 

and schists northwest of Canyon, Colo ...............;...........-............... 42

XX. A and B, Conglomerate at base of "Red Beds" north-northwest of Canyon, Colo....... 42

XXI. A, Two Butte in southwest Prowers County, Colo.; B, water hole in "Dakota" sandstone

near Thatcher, Colo...................____..........._..........»............... 44

' XXII. Map and cross sections showing relations of " Dakota" and associated formations on east

side of Wet Mountains, Colo..................................................... 46

XXIII. Section showing relations of wells in the Arkansas Valley from Pueblo to Coolidge....... 50

XXIV. A, Artesian well on ridge south of La Junta, Colo.; B, flowing well at Rocky Ford, Colo.. 54

XXV. Map of artesian conditions in the Arkansas Valley in southeastern Colorado ............ Pocket.

XXVI. Map showing structure of "Dakota" sandstone in eastern Colorado..................... 56

XXVII. Artesian well 10 miles south of Portland, Colo.................................... 62

XXVIII. Map of part of the Arkansas Valley showing altitude of head of water in "Dakota" sandstone. ........................................................................ 76

FIG. 1. General section showing thickness of strata overlying the "Dakota" sandstone in the Arkansas

Valley............................................................................. 51

2. Diagram of apparatus for illustrating the declivity of head of liquids flowing from a reservoir.. 52
GEOLOGY AND UNDERGROUND WATERS OF THE ARKANSAS 

YALLEY IN EASTERN COLORADO.

By N. H. DARTON.

mTRODTJCTIOX.

In the valley of Arkansas River in southeastern Colorado there is an area of 

considerable extent in which artesian flows are available. During the last ten years 

numerous wells have been sunk to develop this important resource and, in most 

cases in the lower lands, abundant water supplies have been obtained. The principal water-bearing bed is the "Dakota" formation, which consists of two sheets of 

porous sandstone separated by a small bodj* of clay and overlain in the greater 

portion of the area by a mass of impervious shales. The sandstones receive their 

waters from, rainfall and from the sinking of streams along the foothills of the Rocky 

Mountains and on some of the higher slopes south of the Arkansas Vallejr. In the 

passage of this sandstone underground, the waters which it contains are held down 

by the overlying shales, but, as some of the sandstone outcrops are at relatively 

low levels to the east only a moderate head or pressure is sustained. On account 

of this low head, artesian Hows are available only in the lower lands, and one of the 

principal objects of this investigation has been the determination of the area in 

which flows are to be expected. The "Dakota" sandstone and associated formations do not lie level, or even slope regularly to the east, but are flexed into low 

arches and >shallow troughs of considerable complexity of configuration. Accordingly, in investigating this source of water supply, it has been necessarj7 to ascertain 

the structure and distribution of the various formations in order to indicate the 

variations in depth to the water-bearing stratum. The principal results of these 

investigations are set forth: (1) In the geologic map (PI. VI), which shows the distribution of the formations on the surface; (2) in the map, PI. XXV, which shows 

the depth to the water-bearing horizon, the area in which flows are expected, the 

head of the underground waters, and other features, and (3) in the cross sections 

(Pis. VII and XXIII), which show the principal underground features. The 

investigation has been in progress for several years and is an extension of the 

preliminary examination of the region by G. K. Gilbert in ]894 and 1895. a

oGilbert, G. K., Underground waters of the Arkansas Valley 111 eastern Colorado: Seventeenth Ann. Rept. U. S. Geol. 

Survey, pt. 2, 1806, pp. l-5i, Pis. LV1-LXV11.

7
8 s ARKANSAS VALLEY IN EASTERN COLORADO.

For the western portion of the area the maps and texts of the Pueblo, Elmoro, 

Walsenburg, Spanish Peaks, and Pikes Peak folios have been utilized as far as 

practicable. For the central and eastern portions the larger features of the geology 

have been specially mapped, and considerable detailed mapping has been done in 

the region south and southeast of Canyon and Colorado Springs. In the field work 

I have been assisted by Mr. C. A. Fisher, who has examined in detail the Nepesta 

quadrangle and contributed numerous other data. Dr. W. S. Tangier Smith and 

Messrs. C. E. Sicbenthal and W. T. Lee have made observations in certain areas. 

Much valuable information respecting wells has been furnished by Mr. William 

Archer, of the Atchison, Topeka and Santa Fe Railway Company, and Mr. C. H. 

McVay, well driller at Rocky Ford.

GENEKAI* CONFIGURATION.

Eastern Colorado lies on the western portion of the Great Plains, which extend 

from the foot of the Rocky Mountains to the Mississippi Valley. These plains 

present wide areas of tabular surfaces traversed by the broad, shallow valleys of 

large rivers that rise mainly in the Rocky Mountains, and are more or less deeply 

cut by the narrower valleys of lateral drainage (PI. II). .Smooth surfaces and 

eastward-sloping plains are the characteristic features (PI. Ill), especially of the 

uplands, but in portions of the region there are buttes, extended escarpments, and 

canyons of considerable depth. Local areas of sand hills occur, especially along 

the rivers and on some of the high plains, where there is much loose material that 

can be blown by the wind. The altitudes average about 6,00p feet at the foot of 

the mountains and about 3,500 feet along the eastern border of Colorado. Westward 

the mountains rise steeply to altitudes which reach over 14,000 feet in Pikes Peak, 

13,600 feet in Spanish Peaks, and 12,300 feet in Greenhorn Mountain.

The principal streams of the region are South Platte and Arkansas rivers. 

These rise in the mountains, where they flow in deep canyons, but in crossing the 

plains their valleys are wide and average about 200 feet below the surrounding 

higher lands. Near the mountains the Arkansas Valley is bordered in places by 

cliffs of moderate height, but to the east the side slopes are very gentle. The 

altitude in the valley at the mouth of Royal Gorge is 5,400 feet; at Pueblo it is 

4,675 feet, and at the Kansas line 3,350 feet. The average grade from Canyon to 

Pueblo is 15 feet to the mile, from Pueblo to La Junta, 8 feet, and from La Junta to 

the Kansas line, 7.3 feet.

The principal branch of Arkansas River in southeastern Colorado is Purgatory 

River, which rises in the Culebra Range and empties at Las Animas. The region 

adjoining this stream is one of unusual topography for the Great Plains; portions 

of it consist of sandstone plateaus cut by many canyons, that of Purgatory River 

being in places nearly 500 feet in depth. Other branches of the Arkansas crossing 

this plateau are Apishapa and Huerfano rivers, which have also cut canyons of considerable depth. Near the southern margin of the State there rise above, the plains 

two large, prominent mesas the Raton Mesa and the Mesa de Maya both of 

which are due to thick sheets of volcanic rocks.
STRUCTURE. 9 

GENERAL GEOLOGY OF EASTERN COLORADO.

GENERAL RELATIONS.

The eastern half of Colorado is underlain by an extensive series of sedimentary 

formations of late Cambrian to Tertiary age. They are in widely extended sheets, 

which lie nearly level under the plains, but are upturned steeply against the front 

ranges of the Rocky Mountains, in which the underlying granites and gneisses 

appear. The larger surface areas are the later Cretaceous and Tertiary formations, 

the latter covering much of the region north.

STRUCTURE.

The general structure of the region is indicated in PI. XXVI, which shows the 

configuration of the "Dakota" sandstone, not only in its surface outcrops, but also 

under the areas in which it is more or less deeply buried by younger formations. 

From this illustration it will be seen that there is, along the mountain front, a 

general steep monoclinal dip, which affects all of the formations except the youngest.

In greater part the monocline of the front ranges descends into deep basins, 

east of which the strata rise gently. .The most extensive of these basins is one 

having its center near Denver. It extends from North Platte River to the Arkansas, 

and in its lower portion the granite and gneiss which are supposed to underlie 

the plains are 2,000 feet or more below sea level. This basin is terminated on the 

south by an anticline, which crosses the great offset and embayment in the mountain front west of Pueblo," and is a prolongation of the main Front Range of the 

Rocky Mountains. This anticline pitches downward very rapidly from a short 

distance south of Pikes Peak and crosses the Arkansas Valley a short distance west 

of Pueblo, beyond which it coalesces with.a prominent anticline extending southeastward from the Wet Mountain Range. Between these two, in the vicinity of 

Florence, there is a deep synclinal basin lying in the sharp reentrant angle in the 

front of the Rocky Mountains. South of the eastward prolongation of the Wet , 

Mountain anticline there is another deep basin occupying an area of considerable 

extent about the Spanish Peaks. The east side of this basin rises into an anticline 

of moderate prominence, which occupies a broad area in southeastern Colorado, 

coalescing with the extension of the Wet Mountain anticline to the northwest_and__ 

extending far to the northeast, with considerable pitch, as the southeastern margin 

of the Denver basin. At Two Butte there is a small but prominent local uplift due 

to igneous intrusion.

These flexures affect all of the formations except the later Tertiary sands, gravels, 

and clays which cap the divides between the larger valleys. In the Denver and 

Spanish Peaks basins there are extensive deposits of all the formations up to the 

earlier Tertiary. In the Florence basin a small area of the Laramie occurs. The 

anticlines north and south of Pueblo are exhibited mainly in "Dakota" to Niobrara 

formations, and the wide anticline in the southeast'ern portion of the State presents 

extensive exposures of the "Dakota" sandstone, which extend to Arkansas River 

between Las Animas and the vicinity of Lamar.
10 ARKANSAS VALLEY IN EASTEBN COLOBADO.

FORMATIONS.

The sedimentary formations exposed in eastern Colorado represent a large 

part of geologic time from the later Cambrian to the present. Rocks of Silurian 

and Devonian age, however, are absent; the Ordoviciaii and earlier Carboniferous 

appear only in small exposures; the Triassic may be absent in whole or in part; 

the earlier Jurassic is absent; the later Jurassic extends only a few miles into the 

northern portion of the State; a large part of the earlier Cretaceous is absent; and 

there are a number of short breaks in the early, middle, and latest Tertiary times.

Rocks of later Cambrian age appear at a number of points along the Front 

Range, mainly in small embayments west and northwest of Colorado Springs and 

north of Canyon, but it is possible that these are projections from a more extended 

sheet which may underlie the plains eastward. It is evident that the Rocky 

Mountain Front Range was originally a shore line of irregular contour on which 

varying degrees of submergence caused an irregular sequence of overlaps. The 

later Cambrian rocks are sandstones, evidently representing a shore deposit which 

originally had an irregular western margin, much of which is now buried under 

later overlapping sediments.

The Ordovician rocks, which consist mainly of limestones (Manitou and Fremont), with an intervening local sandstone (Harding), are also of restricted occurrence. Outcrops appear in Perry Park, west and north of Colorado Springs, west 

and north of Canyon and Florence, south of Canyon, and southwest of Pueblo. 

At most localities they are overlain unconformably by the Millsap limestone, of 

earlier Carboniferous age, which presents irregular overlap relations from point to 

point. These formations probably extend continuously under the Great Plains, 

but they have not been reached by any borings in eastern Colorado.

_ One of the most prominent members along the Rocky Mountain front is the 

great succession of "Red Beds" which lie on an irregular surface of the granites, 

except in some of the embayments where Cambrian, Ordovician, and earlier Carboniferous rocks intervene. They have been found to be an extension of the 

"Red Beds" and underlying Carboniferous limestone of southeastern Wyoming 

and of the Permian and overlying "Red Beds" of southern Kansas. They are 

readily divisible into three members. The lowest is the Fountain formation, or 

lower Wyoming. This consists of coarse, red grits, which I have found represent 

the Upper Carboniferous limestones of Wyoming. The second is the Tensleep 

sandstone, or "Creamy sandstone" of Eldridge, which has been traced as far south 

as the Manitou embayment. The third member consists of the gypsiferous red 

shales and sandstones known as the Chugwater formation, and is believed to represent the "Red Beds" of eastern Wyoming and the Black Hills. The lower beds 

of this member are of Permian age and the upper beds are either Permian or 

Triassic. It appears to terminate a short distance southwest of Colorado Springs. 

The. "Red Beds" underlie the plains in eastern Colorado and have been reached 

by several deep wells in the Arkansas Valley and by some of the deeper canj^ons 

farther south.

The marine Jurassic, which is well characterized in eastern Wyoming, extends 

only a short distance south into Colorado, where it thins out, but the unconformity

v
CRETACEOUS FORMATIONS, 11

by which it is separated from the ' 'Red Beds" northward continues to the south, 

and represents, throughout the greater part of eastern Colorado, all of Jurassic 

and probably also some of Triassic time. Above this unconformity lies a widespread sheet of fine-grained sediments known as the Morrison formation', evidently 

of fresh-water origin and supposed to represent part of the earlier Cretaceous time. 

It is usually less than 300 feet thick, but appears to underlie all of eastern Colorado, 

although thinning considerably eastward.

The Morrison shales and clays are followed by a succession of coarse-grained 

sandstones, usually designated the "Dakota" sandstone, consisting of two principal masses with an intervening deposit of fire clay, having in all a thickness 

averaging 300 feet. This series underlies all of the eastern part of Colorado, appearing prominently along the slopes of the Front Range and widely in the anticlinal 

uplifts south of Arkansas River. Its upper member undoubtedly represents the 

"Dakota" sandstone, but the medial clay and the lower sandstone series probably 

represent, respectively, the Fuson and Lakota formations, two Lower Cretaceous 

members of the Black Hills. The remarkable uniformity of this tripartite succession and its intimate association with the imderlying Morrison beds is a most 

significant feature over a wide area of the Rocky Mountain province. Several 

years ago fossils of Comanche age were found in the medial, or fire-clay, member 

in the southeast corner of the State, and recently Mr. T. W. Stanton has obtained 

these fossils at this horizon at various localities as far west as Canyon.

The " Dakota " sandstone is succeeded abruptly by a great succession of marine 

sediments, mainly shales, with limestones at certain horizons, representing a long 

interval of later Cretaceous time. The lower portion of this succession consists of 

the Benton group, which is from 400 to 500 feet thick in greater part and comprises two shale formations separated by one of limestone. Its character is constant throughout nearly a half million square miles of the central Great Plains. 

The rocks of the Benton group are exposed in a narrow zone all along the Rocky 

Mountain front and in extensive areas along the slopes of the anticlinal uplifts 

south of Arkansas River. They are succeeded by the calcareous deposits of the 

Niobrara, which attain their greatest development in eastern Colorado. The usual 

succession in the Niobrara is a lower limestone and an upper series of limy shale, 

which in portions of the Arkansas Valley attain a thickness of nearly a thousand 

feet. The Niobrara formation is extensively exposed in the Arkansas Valley east 

of Florence.

Overlying the Niobrara formation is a thick mass of clay known as the Pierre 

shale, which has a wide extent and great thickness hi the Denver basin, in the 

southern end of which it extends as far south as Arkansas River east of Pueblo. 

A smaller area occurs in the Spanish Peaks syncline, and a still smaller one in the 

Florence basin, where it is the source of petroleum. West of Denver the Pierre 

formation appears to have a thickness of more than 7,500 feet; about Florence it 

is more than 3,000 feet thick; and in the Spanish Peaks syncline its greatest amount 

appears to be not more than 2,000 feet. The formation thins rapidly in eastern 

Colorado, where its surface has been extensively eroded in earlier Tertiary times. 

It consists of a succession of dark shalesf with occasional beds of sandy shales 

and sandstones, and usually contains abundant remains of marine shells.
12 ARKANSAS VALLEY I3ST EASTERN COLORADO.

The Pierre sliale gives place rapidly to the Fox Hills formation, which in greater 

part consists of sandstones, and this, in turn, is succeeded by the Laramie formation, a thick succession of sandstones and sandy shales containing extensive and 

valuable deposits of lignite. The latter formation is of fresh-water origin and 

represents the product of late Cretaceous time. It occupies a broad area in the 

Denver basin, in which it extends southeastward from Colorado Springs and northeastward into Wyoming and Nebraska. There is a large area of it in the Spanish 

Peaks basin and a small area in the Florence basin.

In the two larger basins above mentioned the Laramie deposits are overlain 

by extensive beds, mainly of conglomerates and sandstones, which may possibly 

represent the earliest deposits, of Tertiary time. Several formations separated by 

unconformities are comprised in this series, and they constitute the greater part of 

the elevated region culminating in the Spanish Peaks.

There probably is a considerable interval of early and middle Tertiary time 

not represented by deposits in eastern Colorado. The White River group of Oligocene age caps the Laramie formation in the northeast corner of the State and 

occupies an area of considerable extent in the highlands south of Denver, where 

it is known as the Monument Creek formation. These Oligocene deposits consist 

of sands, sandstones, and clays, which probably were once of considerably 

greater extent in eastern Colorado, but were removed by later Tertiary erosion.

On the principal divides in the eastern portion of Colorado there are wide 

areas of the original high plains capped by later Tertiary deposits, consisting of 

sands and gravels, often locally cemented into a limestone grit. This formation has 

been extensively removed along the valleys of Platte and Arkansas rivers, but 

originally it probably extended* to the foot of the higher mountain slopes, as it does 

in Wyoming. The age of this covering of the old high plains is believed to be 

Pliocene, but in the northeastern portion of the State there is also an underlying 

member, the southern extension of the Arikaree formation, which lies on the White 

River formation for some distance.

The Quaternary system in eastern Colorado is represented mainly by the 

alluvial deposits along the valleys and by some remnants of earlier terraces of 

moderate elevation.

GEOLOGY OF THE ARKANSAS VALLEY REGION.

STRATIGRAPHY.

The sedimentary formations exposed in the area drained by Arkansas River 

in eastern Colorado are mainly of Cretaceous age, but along the slopes of the Rocky 

Mountains an extensive series of older formations lies on granite. The various 

formations of Cretaceous age present extensive exposures, but the older formations 

outcrop only in small areas, and there are among them many irregular overlap relations, due to the unevenness of the surfaces on which they were laid down. The most 

extensive developments of the older rocks are in the embayments north of Canyon 

and west of Colorado Springs.
STRATIGRAPHY.

Table of geologic formations of southeastern Colorado.

13

Age.

Cretaceous .................

Carboniferous:

Lower Mississippian. . .

Formations.

Monument Creek. ............

Poison Canyon (Arapahofi) ..

Trinidad sandstonefFoxHills) 

Pierre . . . .........

A.pisttapa._l, 

Timpas....robraragrOUP-- 

Carlile.....! 

Greenhorn. tflenton group . . . 

Graneros.J

fTensleep, ) 

<Fountain [-Lower Wyoming.. 

l(B'adito) j

Principal character.

Sand, gravel, and clay ............................. 

Coarse sandstone and conglomerate on clays and 

marls.

Sandstone conglomerate; some clay ...............

Dark-gray shale with concretions. . ....... .......

Gray sandstone, fire clay in middle ..........

Gray to maroon joint clays with limestone and 

sandstone layers. 

Bright-red sandy shales with thin limestone layers 

and gypsum; reddish sandstone at top.

Fine, even-grained, gray to pink sandstone;' some 

shale.

Thickness,

te»t. 

50 

50 

-, 150 

200 

2,900

475 

1,900 

2,000 

150 

1,300-3,000 

550 

200 

200 

60 

200 

200- 300 

20 

200

100

200 

600-1,200

80- 200 

100 

100

100- 270 

< 40- 100

CAMBRIAN STSTEM.

In the Manitou embayment west of Colorado Springs and in a small area north 

of Canyon rocks of Cambrian age appear lying on the granites. The deposits north 

of Canyon consist of a thin mass of sandy and cherty beds of variable local development at the base of the Manitou limestone. They have yielded a trilobite, Ptychoparia, a form of Upper Cambrian age. In the Manitou embayment west and northwest of Colorado Springs the Manitou limestone is nearly everywhere underlain by 

10 to 80 feet of sandstones, mostly of pinkish color, containing Upper Cambrian 

fossils. Some of these were obtained by Doctor Cross from the east branch of Trout 

Creek, 45 feet above the granite; they comprised Lingulepis sp. (?) and a lAngula 

of elongate form allied to jrinnseformis of the Upper Cambrian of Wisconsin.

This sandstone appears at Manitou and extends northward along the west side 

of the Garden of the Gods to beyond Glen Eyrie, where it contains upper Cambrian 

fossils. One section which has been reported has, beginning at the base, 26 feet of 

greenish-white sandstone, 4 feet of coarse dark-green sandstone, 6 feet of coarse
14 ARKANSAS VALLEY IK EASTEBN COLORADO.

gray sandstone, and 20 feet of brick-red sandstone with green layers, overlain by 

Ordovician limestone. A small area containing fossils was found southwest of 

Monument Park, and, according to Mr. W. T. Lee, a quartzite which is presumably 

of the same age appears on Deadman Creek south by west from Monument station.

OKDOVICIAN SYSTEM.

Rocks of Ordovician age are extensively exposed in the embayment north and 

northeast of Canyon and west of Colorado Springs, and two small areas have recently 

been observed southwest and south of Canyon. They consist of limestones and 

sandstones usually lying on a thin deposit of Cambrian sandstone, or quartzite, and 

sometimes they overlap on the granite and schists. In the Canyon district the 

Ordovician is represented by the Manitou limestone, Harding sandstone, and Fremont 

limestone (PI. V, A). These have been described in detail by Dr. C. D. Walcott, " 

mainly in connection with the occurrence of fish remains, and by Dr. Whitman Cross 

in describing the region northeast of Canyon in the Pikes Peak folio. The following 

members are described by Doctor Cross:

Manitou limestone. This limestone is extensively exhibited in Oil Creek Valley, 

Garden Park, where it consists of fine-grained pink or reddish dolomite less than 

100 feet thick. It occurs in the Manitou region, where it contains Opliileta, Camerella, and other characteristic Ordovician fossils.

Harding sandstone. This formation consists mainly of fine, even-grained, granular sandstone in alternating bands of light-gray and pinkish or variegated colors, 

with a few bands of dark-red or purplish sandy shale, having a maximum thickness 

of about 100 feet (Pis. VIII and XIX,). The lower part is sometimes calcareous 

and develops into a thin fine-grained dolomite. This formation contains fish remains 

at the Canyon locality. In Garden Park the sandstone rests with apparent conformity on the Manitou limestone, but to the southeast it overlaps on the basal sandstone and near Canyon on the gneiss. At Canyon the formation is 86 feet thick 

and consists of gray, reddish, and purplish-brown sandstone and shales with many 

fossils of early Trenton age. A small outlier of sandstone, apparently of this -formation, underlying the Millsap (Carb'oniferous) limestones in the slopes west of Beulah, 

is mapped by Gilbert in the Pueblo folio.

Fremont limestone. Overlying "the Harding sandstone with apparent conformity, there occurs a bluish-gray or pinkish dolomite of uneven grain, sometimes 

arenaceous, which gives rise to very rough weathered surfaces." Its thickness in 

Garden Park is about 100 feet, but increases southward to a maximum of 270 feet 

near Canyon, partly through the development of an upper fossiliferous member. 

In Garden Park it is characterized especially by the coral Halysites catenulatus, and 

also contains a molluscan fauna like that of the upper Trenton in New York. It 

appears to be restricted to a small area in Garden Park and vicinity and a narrow 

outcrop extending" southward past Canyon. These formations all end a short 

distance southwest of Canyon by overlap of later deposits, but two small areas were 

found, one near the road 4 miles southwest of Canyon and another at the foot of the 

mountain on one of the branches of Chandler Creek, 7 miles nearly due south of 

Canyon.

a Bull. Geol. Soc. America, vol. 3, pp. 153-167.
PALEOZOIC FORMATIONS. 15

At Manitou and for some distance northward and in the Trout Creek Valley 

(Manitou Park) there are other areas of Manitou limestone iinder lying the " Red 

Beds." On Trout Creek this limestone has yielded distinctive Ordovician fossilsDoctor Peale gives the following section of the exposure of Manitou limestone 

and associated formations at Glen Eyrie: 0

Geologic section of basal rocks near Glen Eyrie, Oolo.

Ago. Description. Thickness.

Carboniferous (?).

Ordovician.

Cambrian.

Gray, purplish, and yellow limestones.......................

Red shaly limestones, with fragments of Ordovician fossils. 

Limestones with, interlaminated shales.....................

lied limestone with flint nodules............................

Red limestone................................................

Ked shaly limestone..........................................

Red limestone................................................

Irregularly laminated limestone.............................

Red and greenish limestone.................................

Briek-red sandstone with green layers......................

Coarse gray sandstone.......................................

Coarse dark-green sandstone................................

Coarse grayish-white sandstone..............................

Granitefeet. 

279 

4 

7 

7 

2 

1 

1 

3

5

20

6

4

20

On Deadman Creek, 6 miles south of Perry Park, a small outlying area has been 

investigated by Mr. Willis T. Lee. 6 The rocks are cherty limestones in layers interstratified with red clay, overlying a few feet of deep-red quartzite of supposed Cambrian age. The fossils obtained were examined by Doctor Weller, who found the 

best preserved specimens to be Dalmanetta testudinaria of Ordovician age.

CARBONIFEROUS AND TKIASSIC SYSTEMS.

MiUsap limestone. This limestone of Lower Carboniferous age appears in a 

few isolated outcrops west of north of Canyon and west of Colorado Springs. North 

of Canyon it lies on the Fremont limestone and is immediately overlain by the 

" Red Beds " of the Fountain formation. The locality in which the largest amount 

is exposed is in the angle between Oil and Millsap creeks, where there are^ about 

30 feet of thinly bedded, variegated, dolomitic limestones, with a few thin sandstone layers. Chert nodules in the upper limestones carr}^ casts of Spirifera rockymontana and Athyris subtilita. The limestone appears at several points among 

the outcrops on the slope of the mountain northwest of Canyon. In the limestone 

area west of Colorado Springs, fossils of Carboniferous age have been discovered 

by Prof. A. W. Grabau. In a letter Professor Grabau states that they are remains 

of Spinfer, either rockymontana or centronatus, and small producti. They occur 

in a light-gray, compact limestone about 10 feet thick, lying from 10 to 15 feet 

below reddish and purplish shaly beds at the base of the Fountain formation. 

About 100 feet lower some other remains were found which-were not determined.

a Peale, A. C., Geology of the South Park division: Seventh Ann. Repti U. S. Geol. and Geog. Surv. Terr., 1874, p. 201 

& Lee, Vf. T., Geology of the Castle Hock region, Colorado: Am. Geologist, vol. 29, pp. 96-97.
16 ARKANSAS VALLEY IN EASTERN COLORADO.

A small area of this'limestone appears on the slopes west of Beulah, as described 

by Mr. Gilbert.' In this locality its thickness is 200 feet and it consists of gray 

and purplish limestone with some shale in its lower part. Spirifera rockymontana 

occurs near its middle. It lies on supposed Harding sandstone, the Fremont 

limestone apparently being absent.

The "Red Beds." The most conspicuous sedimentary foivmations exposed 

along the Rocky Mountain Front Range is the succession of red sandstones known 

as the "Red Beds." For the greater part of their course they lie directly on the 

granite, but in the embayment about Manitou and Canyon they are locally underlain by limestones. Near the Arkansas divide, at Palmer Lake, they are overlapped by Monument Creek beds; west of 'Monument, southwest of Colorado 

Springs, and south of Canyort, they are faulted down, and southwest of Pueblo 

they are locally overlapped by the Dakota and associated formations. The thickness of the "Rod Bods" is variable, but it is rarely less than 1,000 feet, and in the 

Garden of the Gods it is greater. Part of the variation is due to the uneven floor, 

the thicker masses of the bods lying in the deeper depressions. The "Red Beds" 

are also exposed extensively in the Purgatory and other deep canyons in the High 

Plains south of Arkansas River. The rocks are mainly coarse-grained red grits 

and red sandstones.

In the Manitou embayment there are three divisions of the "Red Beds." 

The uppermost consists of about 100 feet of rod shales, a thick bed of gypsum, 

and thin beds of limestone, and is believed to represent the Chugwater formation 

of eastern Wyoming (upper Wyoming beds). The medial member consists of about 

200 feet of fine-grained, light-colored, massive sandstone, which in the Boulder 

region has been designated the Lyons sandstone by Professor Fenneman." The 

lowest formation, the Fountain, is about 1,000 feet thick and consists of coarse 

red grits. In southeastern Colorado the upper part of the "Red Beds" consists 

of gypsum and red shales, which may represent the Chugwater (Lykens) formation; 

as yet, however, no evidence has been found on which to base correlation.

The "Red Beds" are extensively exposed in the Garden of the Gods and for 

some distance north and south, dipping nearly vertical. At the south they are 

cut off by the great fault which passes along the base of Cheyenne Mountain. They 

give rise to the picturesque features of the Garden of the Gods, the Gateway 

marking the outcrop of the uppermost hard red stratum. Next above these are 

some softer striped red sandstones, about 100 feet thick, not well exposed at the 

Gateway, and then the white sandstone which outcrops a short distance east of 

the Gateway. This last bed is about 100 feet thick, moderately fine grained, massive, and cross-bedded, and represents the "Creamy sandstone" of Eldridge (or 

the Lyons sandstone of Fenneman), at the top of the lower Wyoming. The occurrence of this lighter colored, finer grained sandstone at this horizon is general along 

 the foothills of the Rocky Mountains from Manitou north, and in the Laramie 

Range, Black Hills, and Bighorn Mountains, being the'Tensleep sandstone of the 

Bighorn slopes. Near the Garden of the Gods it is similarly succeeded abruptly 

by soft, red shales, including near the base thin limestones believed to represent 

the Minnekahta limestone and gypsum deposits above, and extending to typical

"Bull. U. S. Oeol. Survey No. 265, 190.5.
BED BEDS. 17

Morrison shale. This .upper, series of red shales, limestones, and gypsum 

undoubtedly is equivalent to the upper Wyoming of Eldridge (or Likens formation of Fenneman). At its base, overlying the white sandstone, are 55 feet of soft, 

red shale and red clayey sandstone (Opeche horizon), 25 feet of thin limestone 

layers with red shale intercalations (Minnekahta), and 30 feet of red shales surmounted by a 30-foot bed of gypsum, ovelaiii by Morrison. shales. The following 

section was measured a short distance north of the Gateway to the Garden of 

the Gods:

Section of the upper "Bed Beds" between the Gateway of the Garden of the Gods and Glen Eyrie.

Clays and shale (Morrison).

Upper Wyoming beds: Feet. 

Gypsum........---.....-.....-......-.....--.-.......-..........i.... ................... 30

Red shales............................................................................... 30

Limestone..................... i I 3

Red shales with thin limestones.. H Minnekahta ).......I....................................J 22

Purple limestone, thin layers..... I I 1

Soft red shale and sandstone (Opeche)...................................................... 55

Top of lower Wyoming beds:

Massive white sandstone (Lyons or Tensleep).

To the south the "Eed Beds/' both upper and lower, preserve the same general 

features to the great fault at the foot of Cheyenne Mountain, though showing local 

variations. At the Gateway the 30-foot bed of gypsum is a conspicuous feature, 

and there is a thin bed of gypsum a short distance below its base. Just below the 

Gateway these beds are offset and twisted, so that they are locally deflected some 

distance west of the general line of strike. Oh the roadside south of the Gateway 

there are seen very coarse, cross-bedded materials in the upper part of the Fountain 

formation, giving place abruptly to the fine-grained red sandstones and red gypsiferous shales of the upper Wyoming, all vertical or dipping steeply eastward, as 

shown in PI. IX, A.

In the railroad cut in the western portion of Colorado City the following section 

is exposed:

Partial section of" Eed Beds" at Colorado City.

Sandy shales, etc. (Morrison). t ' Feet. 

Talus and "Red Beds "...........................................................1.......L ... 50

Impure gypsum..................................'............................................ 5

Red shales and soft sandstone with 3 feet of thin beds of gypsum near top............................ 60

Soft, massive, red sandstone. _ ...__.._......_.... ..........-..._._..._......_.._._._.__....._.. 55

The section consists of upper Wyoming "Red Beds," except that the basal 

member may possibly be the upper part of the Lyons.

When the "Eed Beds" next appear, beyond the fault southwest of the village 

of Fountain, they are seen to consist, after the first 1 or 2 miles, almost entirely of 

coarse-grained materials without the uppermost gypsiferous red shales and to be 

overlain directly by Morrison beds. This coarse deposit, constituting the entire " Red 

Bed" section of this region, was designated the Fountain formation by Cross, a 

name which has been employed by Gilbert in the region still farther south. Here, as 

in the Manitou and Perry Park embaymehts, it is underlain by Millsap limestone.

The Fountain formation in the region extending from southwest of Fountain 

to Canyon consists mainly of coarse-grained, crumbling, arkose sandstone in massive 

4551 No. 52 08-^-2
18 ARKANSAS VALLEY ITST EASTERN COLOEADO.

beds, usually cross-bedded. Many conglomeratic streaks, occur and a basal conglomerate often appears, notably on the road northwest of Canyon, where it lies on 

an eroded surface of Millsap limestone (PI. XX). The beds are prominently reddish, 

but some are gray and others are mottled gray and red. Finer grained materials, 

nearly all of a bright brownish-red color, often occur. The thickness is estimated 

as 1,000 feet, but varies considerably. Nearly everywhere the formation is separated from the granites and gneisses by limestones of Ordovician age, but in places 

it overlaps the crystalline rocks, and at some localities the underlying limestones 

are faulted out. In the vicinity of Canyon and at a small locality on Cripple Creek 

at the head of Garden Park the underlying Millsap limestone appears. In the region 

southwest of Pueblo the thickness of the Fountain formation, as measured by Mr. 

Gilbert, is 2,100 feet, including practically all of the formation, but it thins out to 

the southward and is absent for some distance along the foot of Greenhorn Mountain.

At the south end of Greenhorn Mountain there appears a similar succession of 

rocks which Mr. Hills has named the Badito formation, probably corresponding 

to the Fountain formation. It comprises an upper member, about 100 feet thick, 

generally massive or thick-bedded, but sometimes shaly on the weathered surface, 

and a lower member, of about the same thickness, of very coarse brownish-red conglomerate. Lying on granites and gneisses to the south this succession appears 

again in the Culebra Range, where it expands to a great thickness. The Carboniferous limestones appear again on this range about Veta Pass, and they extend 

southward into New Mexico. This area was described in considerable detail by 

Mr. Endlich, of the Hayden Survey, who mapped the lower portion of the series as 

"Lower Carboniferous," and several thousand feet of "Red Beds" as "Upper 

Carboniferous."

In 1902 Mr. Willis T. Lee a collected fossils and made a section southwest of 

Spanish Peaks. These fossils, obtained mostly from the lower hundred feet of the 

formation, were identified by Dr. Stuart Weller and found to be Upper Carboniferous. The species were as follows:

Zaphrentis sp. undet. 

Orbiculoidea convexa Shum. 

Orbiculoidea missouriensis Shum. 

Chonetcs mesolobus N. and D. 

Productus longispinus Sow. 

Productus costatus Sow. 

Productus cora D'Orb. 

Spirifer cameratus Morton. 

Spirifer rockymontanus Marcou. 

Squamularia perplexa McCh. 

Seminula argentea Shep. 

Acanthopecten carboniferus Stev. 

Astartella concentrica McCh. 

Nucula ventricosa H. 

Lida bellistriata Stev. 

Pelecypod (genera and sp. undet.). 

Bellerophon percaririatus Con.

Patellostium montfortianum N. and P._

Bellerophon sp. undet.

RqJ-ella verrucelifera White.

Soleniseus brevis White.

Soleniscus sp. undet.

Sphzerodoma texana Shuhr.

Sphserodoma sp. undet.

Trachydomia wheeleri Swall. var.

Naticopsis altonensis McCh.

Naticopsis altonensis var. gigantea M. and W.

Plenrotomaria perizomata White.

Pleurotomaria (several species undet.).

Murchisonia copei White.

Orthoceras sp. undet.

Syringopora sp.

Campophyllum torquium Owen.

Straparollus catilloides Con.

Euphemus carbonarius Cox.

a Carboniferous of Sangre de Cristo Range, Colorado: Jour. Geol., vol. 10, pp. 393-396.
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 62 PL. I

MAP OF CENTRAL WESTERN UNITED STATES, SHOWING AREA TREATED IN THIS REPORT

0 50 100 200 300 miles
U. 8. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 52 PL. II

RELIEF MAP OF THE DRAINAGE BAS'N OF ARKANSAS RIVER IN COLORADO,
A. THE HiGH PLA1MS IM EASTERN COLORADO. 

Grass, sunshine, and solitude.

B, VIEW OM THE GREAT PLAINS IN EASTERN COLORADO. 

Shows ranch situated in shallow drainage basin.
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 52 PL. IV

A. HAYSTACK BUTTE, PUEBLO COUNTY, COLO, 

Typical flat-topped outline of Timpas limestone or Carlile shale.

£. APISHAPA CANYON NORTHWEST OF THATCHER, COLO. 

A typical sharp-edged flat-bottomed canyon in " Dakota " sandstone.
U. 8. GEOLOGICAL 6URVEV PROFESSIONAL PAPER NO. 62 PL. V

A. "DAKOTA" HOGBACK AT CANYON, COLO. 

Valley of " Red Beds" and slopes of Morrison beds to left; minor hogbacks of Timpas limestone to right. Photograph by I. C. Russell.

13 "DAKOTA" HOGBACK RlDGE j MILES SOUTHWEST OF CANYON, COLO. 

Looking north. Valley of Graneros shale in foreground; mountains of gneiss in distance. Photograph by C. D. Walcott.
U. 8. GEOLOGICAL SURVEY PROFESSIONAL PAPER No. 52 PL. VIII

A. QUARRY IN HARDING SANDSTONE ON EAST SLOPE OF MOUNTAINS 2± MILES NORTHWEST OF CANYON, COLO,

Looking north Granite to left, Harding sandstone in quarry, Fiemont limestone and " Red Beds" in slopes to right. Photograph by

C, D. Walcott.

B. FREMONT LIMESTONE NORTHWEST OF CANYON, COLO. 

Shows irregular erosion forms.
U. 8. GEOLOGICAL SURVEV PROFESSIONAL PAPER NO. 52 PL. IX

A. VERTICAL LOWER "RED BEDS," GARDEN OF THE GODS, COLORADO. 

The harder portions rise in pinnacled forms.

£. THE STONEWALL ON PURGATORY RIVER 30 MILES WEST OF TRINIDAD, COLO. 

Looking southeast across valley of Benton and Pierre shale to ridge of overlying sandstones.
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 52 PL. X

£*^'%K "A

r* '&U. .» ..-.-. '^s: s»-

A DAKO1 A SANDSTONE IN HOGBACK RluGE 2 MILES SOUTHWEST 

OF CANYON, COLO.

Looking north. Shows upper and lower sandstone members with intermediate shales.

£. BONE-BEARING SANDSTONE IN MIDDLE OF MORRISON FORMATION IN GARDEN PARK NORTH OF CANYON, COLO.

Photograph by I. C. Russell.
UPPER CARBONIFEROUS FOSSILS. 19

Other fossils, found in loose fragments, were as follows:

Derbya crassa M. and H. 

Hustedia mormoni Marcou.. 

Allorisma subcuncatum M. and H. 

Schizodus wheelcri Swall.

Bellerophon (large sp. undet.). 

Temnocheilus winslowi M. and W. 

Phillipsia sp. 

Large fish spine.

The following section is given by Mr. Lee:

Section at (he crest of the Culebra Range, between Middle Fork and North Fork of Purgatory River.

, Feet.

Hard quartzitic conglomerate._.._._...._._...._....._..-..-.--..-.--........._....._......... 10

Dark shale.......__.--_.--.-..-.........-.....-..-_..-..---.-.-.--.-.-.-......-............ 5

Limestone, f ossilifcrous....................................................................... 2

Red sandstone, with bands of red shale and irregular masses of limestone.......................... 12

Greenish argillaceous sandstone............................................................... 4

Pink sandstone, argillaceous above, conglomeratic below......................................... 18

Fossilifcrous limestone,...................................................................... 4

Deep-red sandstone, conglomeratic at the base, shaly near the top. ............................... 10

Limestone, arenaceous near the base.......................................................... 20.

Massive, light-colored grit, coarse and conglomeratic-............................................ 13

Banded sandstone and limestone intimately commingled; the limestone is often in more or less rounded

masses; irregular beds of gravel occur in places....--....-.-.-..---.-.-.-..-...-..-:_..______._ 6

Nodular limestone.......................................................................... 3

Massive limestone........................................................................... 8

Shale with limestone nodules................................................................. 3

Massive limestone.......................-.....-..-..-......'................................. 23

Coarse sandstone, conglomeratic in the 'lower half............................................... 20

Massive grit (local unconformity)............................................................. 8

Calcareous shale, passing to black shale, with limestone nodules near the top....................... 10

Fossiliferous limestone with sandstone layers; cup corals abundant................................. 15

Massive limestone. ........................................................................... 6

Shale-..........-....---.....-------... ----.---.----.---.-----.----.-..-.--------... 8

Coarse grit................................................................................. 2

Sandstone with large nodules and irregular masses of limestone................................... 10

Shale with bands of sandstone and limestone................................................... 25

Banded limestone-.......................................................................... 4 12

Soft black shale, fossiliferous. .................................................................. 28

Coarse grit- .r ... ..................-.........-....-.....-..-...:............................ 9

Black shale.................................................................................. 6

Coarse grit, conglomeratic in places........................................................... 2 20

Dark shala, with limestone nodules and thin seams of sandstone; "runs to massive limestone in places;

becomes red and arenaceous near the base................................................... 45

Coarse grit- ................................................................................. 7

Dark-red shale, with nodules and irregular masses of limestone................................... 10

Limestone................................................................................. 4

Red to black micaceous shale, with bands of sandstone near the base, and limestone nodules near the top. 12

Coarse grit.................... 1.............................. i .............................. 10

Red grit and conglomerate.............. - _- .................................................... (?)

Crystalline rocks of the mountains.

A small collection of fossils was also obtained from the western slope of Veta 

Pass, 5 miles above Placer, in a succession consisting of sandstones, limestones,
20. ARKANSAS VALLEY IN EASTERN COLORADO.

shales, and conglomerates similar to those above described. The following Upper 

Carboniferous forms were found at this locality:

Zaphrentis sp.

Orbiculoidea sp. 

Derbya crassa M. and H. 

Chonetes granulifera Owen. 

Chonetes mesolobus N. and P. 

Productus ncbrascensis Owen. 

Productus costatus Sow. 

Spirifcr cameratus Morton. 

Squamularia perplexa McCh.

Hustedia mormoni Marcou. 

Aviculopecten occidehtalis. 

Astartella concentrica McCh. 

Schizodus wheeleri, Swall. 

Bcllerophon percarinatus Con. 

Bellerophon inspeciosus White? 

Soleniscus sp. 

Conularia? sp. 

Orthoceras sp.

Seminula argentea Shep.

The Millsap and underlying limestones were no.t found by Mr. Lee in the Culebra 

Range, although possibly there may be small outliers of them in portions of the 

range which he did not visit. The strata overlying the section given above consist 

of several thousand feet of red and gray sandstones, mostly coarse, extending to 

the base of the Morrison and representing the Fountain formation.

In the canyon of Cuchara River, near the north line of Huerfano County, the 

upper portion of the "Red Beds," here termed the Badito formation by R. C. Hills, 0 

is exposed. At Red Rocks, in the canyon of Purgatory River, in the northern portion 

of Las Animas County, there are extensive exposures of the "Red Beds" and an 

overlying bed of gypsum which appears to belong with them. Several hundred 

feet are exposed, consisting at the top, under the gypsum, of a coarse, conglomeratic, massive, red sandstone, which merges downward into more regularly stratified 

red sandstones, with occasional layers of sandy red shales. In the uppermost sandstone the writer found a small bone fragment, apparently a portion of a scapula of 

a bolodont, which would suggest that this member of the formation is of Triassic age.

Partial section of " Bed Beds " in Plum Canyon near Purgatory River, Las Animas County, Cdlo. 6

''Dakota" sandstone: Feet. 

Two massive sandstones, with clay between................................................. 140

Morrison formation:

Variegated shales, with thin limestone layers............................................... 85

Dark shales, with irregular masses of gypsum................................................... 15

Gypsum, with streaks of clay....................................................'........'..... 1J

Variegated shale, with much gypsum in masses up to a foot in diameter. ........................... 8

Gypsum in layers sometimes separated by layers of clay......................................... 25

Massive gypsum....................'........................................................ 5

Red gypsiferous shales, soft and regularly bedded............................................... 30-40

Red calcareous sandstone, oolitic, cross-bedded, layers variable in thickness and character, shaly near 

top, grading into gypsiferous shales ......................................................... 60

Red sandstone, massive, cross-bedded. -.....-.-.--.---.----....---...--...-.-.....-........ 175-200

Red arenaceous shales....................................................................... 6

Red sandstone- -.-.-..---...---.-...-.....-......-.-.-.--..-...-............^............... 1

Fine, red shale.............................................................................. 4

Even-bedded red sandstone......... t ........................................................ 9

Red arenaceous shale........................................................................ 2

Red sandstone, cross-bedded................................................................. 40

a Hills, R. C., Description of the Walsenburg district: Geologic Atlas U. S., folio 68, U. S. Geol. Survey, 1900. 

& Lee, W. T., Morrison formation of Colorado :4 Jour. Geol.. vol. 9, 1901, p. 346.
MORRISON FORMATION. 21

Feet. 

Loose red sandstone, alternating with shale.................................................... 15

Massive red sandstone.............-.....-....-.-..-.....-.----...-----................-.-.-- 5

Soft red sandstone containing ripple-marked, hard layers. ..._...-......-.....................-..- 30

White, hard, argillaceous limestone, thin layers, contorted........................................ 4

Red sandstone to river bottom. ............................................^ ^................ 15

The correlation of these " Red Beds" with the Wyoming formation is reasonably 

certain when their character and relations are considered, and apparently the upper 

'gypsiferqus series represents the upper Wyoming. They underlie a wide area in 

southeastern Colorado and have been penetrated by some of the wells. The well at 

La Junta reached them at 606 feet and continued in them to 1,150 feet. The well 

at Bloom penetrated them from 400 feet to 1,162 feet without reaching their bottom. 

They also appear in some of the deep canyons south of the west end of Mesa de 

Maya, but their character in that region was not ascertained.

The "Red Beds" are exposed over an area of about 3 square miles in the Two 

Butte uplift on Two Butte Creek in Prowers and Baca counties. They are described 

by G. K. Gilbert, 0 who estimates that over 600 feet are exhibited. The lowest 

beds are sandstones and shales, the latter predominating somewhat. Some of the 

beds are orange or yellowish. These are overlain by white limestone 5 to 10 feet 

thick, which was found to be very like the Minnekahta limestone in thin-bedded character and general aspect in the outcrops. This limestone is overlain by brick-red 

shales about 150 feet thick, becoming sandy at the top and merging into a massive 

red sandstone over 300 feet thick, which forms prominent bluffs along the creek and 

caps the butte, which was uplifted by the laccolithic intrusion of the igneous rock. 

At one place this sandstone is parted by 40 to 50 feet of shale. Parts of the sandstone are buff, yellow, or gray, and somewhat resemble the ""Dakota" sandstone, 

for which it has been mistaken here and elsewhere. It is, however, separated from 

the "Dakota" and probably represents the Exeter sandstone of Mr. Willis T. Lee, 

which appears to the south along Cimarron River. '

CRETACEOUS SYSTEM.

Morrison formation. This formation extends along the base of the Rocky 

Mountains, where it outcrops frequently and presents very characteristic features. 

In a few localities, as along the foot of Cheyenne Mountain and south of Canyon, 

it is cut off by faults and for short distances it is overlapped by younger formations. 

It is also exposed in some of the canyons eastward, notably in the deeper ones of 

eastern Las Animas County. Its general character is nearly uniform throughout, 

consisting of light-colored massive clays, or "joint clays," with thin beds of limestone and sandstone of fresh-water origin, containing bones of saurians of the 

so-called " Atlantosaurus fauna." Its thickness averages less than 200 feet in 

most cases. It presents frequent and rapid variations in the local succession of 

beds, but the preponderance of "joint clays" of chalky aspect and the occurrence 

of maroon and purplish layers among them are characteristic features. The name 

Morrison was given by Eldridge, from the town of Morrison, where the formation 

is extensively developed. The Morrison beds lie unconformably on the Chugwater

o Gilbert, 0. K., Laccoliths in southeastern Colorado: Jour. Geol., vol. 4,1896, pp. 816-825.
22 ARKANSAS VALLEY IN "EASTERN COLORADO.

or gypsiferous "Red Beds" for many miles, and, southwest of Colorado Springs, 

overlap onto the " Red Beds" of the Fountain and Badito formations. In eastern 

Las Animas County they lie on a bed of gypsum. From the saurian remains which 

have been obtained so abundantly from the Morrison beds west of Denver and north 

of Canyon, the formation is regarded as latest Jurassic by some paleontologists and 

as earliest Cretaceous by others, but from its close connection with the overtying 

sandstone, the writer considers it preferable to class it as Cretaceous.

The formation is well exposed a short distance north of the Gateway to the Garden 

of the Gods, where its thickness is 130 feet. The basal beds here lie on the thick 

deposit of gypsum at the top of the Chugwater formation and consist of ashgray, massive shales with several thin limestone layers and a few streaks of shales 

with clay pebbles. These grade up into typical pale, greenish-gray and maroon, 

massive clays with a few thin layers of fine-grained, light-colored sandstone 

abruptly overlain by coarse-grained, buff-colored "Dakota" sandstone. At 

Colorado City the Morrison beds are exposed only in part in the railroad cut, the 

top and bottom members being covered by talus. The beds stand nearly or quite 

vertical. To the west are 55 feet of pale greenish-gray, sandy shale, mostly massive, 

with thin layers which arc overlain (to the cast) by a 15-foot bed of soft, pale greenishgray sandstone. The formation is cut off by the fault south of Colorado City, but 

reappears in the cmbayment north and northeast of Canj^on. In Garden Park, 

on Oil Creek, it has a thickness of about 350 feet, according to Cross, a and consists 

mainly of greenish, pinkish, or gray shales or marls with sandstone layers at various 

horizons. It usually lies on the Fountain formation, but overlaps locally onto the 

granite. In this region the formation has yielded large numbers of dinosaur remains.

Hatcher 6 has described the Morrison formation and its relations in the Garden 

Park area and given some details regarding the fossiliferous horizons. He estimated the thickness at 450 feet, placing the upper limit higher than Cross did, so 

as to include the highest sandstones and shales containing dinosaur remains. 

The bones have been obtained in largest number from a thick sandstone layer about 

150 feet above the base of the formation shown in PI. X, B, but some occur 

30 feet below this stratum and others have been found at various horizons above, 

both in shale and in sandstones. Just below the main bone-bearing sandstone bed 

there is a layer of clay with thin limestone beds containing numerous fresh-water 

gasteropods, and at a somewhat lower horizon, a marly layer with abundant remains 

of unios. These shell fossils have been described by C. A. White, who classes them 

as Jurassic because they occur with supposed Jurassic dinosaurs, but states that 

otherwise they might be much younger, so that they throw no light on the age of 

the beds. The late J. B. Hatcher found an Inoceramus at the Garden Park locality.

Near .Canyon there are excellent exposures of Morrison formation on the west 

slope of the "hogback." At the top are alternating sandstones and shales, 150 feet 

thick, lying on purple and green shales 160 feet thick, at the base of which there is 

a prominent layer of limestone 4 feet thick, which contains many fresh-water shells. 

Below this are 40 feet of pale bluish-green massive shales lying on sandstones. The

a Cross, Whitman, Description of the Pikes Peak district: Geologic Atlas U. S., folio 7, U. S. Geol. Survey, 1894, p. 2. 

* Hatcher, J. B., Annals Carnegie Museum, vol. 1,1901, pp. 327-341.
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 52 PL. XI

THE STONEWALL ON PURGATORY RIVER WEST OF TRINIDAD, COLO.; A MONOCL1NAL 

RIDGE OF "DAKOTA" SANDSTONE.

A. Looking west to Culebra Range. B. Looking south, showing red valley to right and valleys of Graneros

and overlying shales to left.
MORRISON FORMATION, 28

total thickness appears to be nearly 400 feet. Four miles south of Canyon the 

formation lies directly on granite, as shown in PI. XVII, B, and described on page 42.

Six miles south of Canyon the Morrison beds are faulted out, or overlapped by 

younger strata, and do not reappear until in the vicinity of Mineral Creek south of 

Florence, whence they extend southward into North Creek Valley. According to 

Mr. G. K. Gilbert, the "Dakota" sandstone lies directly on the Fountain formation 

north of Beulah for several miles, but probably the Morrison beds formerly covered 

the region and were removed by pre-" Dakota" erosion. The Morrison beds appear 

south of Beulah, where, as described by Mr. Gilbert," they consist chiefly of red 

shale with a few layers of hard, red sandstone beds about 70 feet thick. They are 

faulted against the gneiss and also overlap onto that rock for a portion of their 

course; near the contact they are paler in color, white and orange predominating, and no reds appear. The formation comes up again for 5 miles at the south 

end of Greenhorn Mountains, lying partly on gneiss and partly on the "Red Beds." 

Its thickness here, according to Hills,6 is^270 feet, the lower portion consisting of 

about 60 feet of soft white sandstone, conglomeratic at base. The middle portion 

is a series of pinkish and greenish massive clays, and the upper beds are variegated 

shales and clays, alternating with bands of fine-grained limestone often containing 

vermilion-colored cherts. Hills states that there is considerable doubt as to the 

true position of the formation in the time scale, but assigns it provisionally to the 

Jurassic.

Mr. Willis T. Lee has made a special study of the Morrison formation in the 

southern Colorado region,0 and his work has thrown much light on its distribution 

and components. He describes its continuation southward along the foot of the 

Rocky Mountains west of the Spanish Peaks into New Mexico and its existence in 

the deep canyons of Las Animas County, Colo., and southward. He has found 

that it presents its usual characteristics, regular stratigraphic position and dinosaur 

remains. The first exposures east of the foot of the mountains are in Cuchara and 

Huerfano canyons in western Huerfano and southern Pueblo counties, where Hills 

reports the formation as 100 feet thick and consisting of variegated shales and clays 

alternating with layers of fine-grained limestone. In Apishapa Canyon north of 

Thatcher the typical Morrison is reported by Lee, underlying the "Dakota" sandstone. There are extensive exposures in Purgatory and adjacent, canyons where 

the "Red Beds" are uplifted. Mr. Lee gives the following section, in Plum Canyon 

near its mouth:

Geologic section of Morrison formation in Plum Canyon, Las Animas County, Colo.

''Dakota": . Feet.

Massive sandstones.....-_._.__,_._.....-..-...-.-............-...._...-............___._ 140

Morrison: v

Greenish clay and shale, soft and fine grained................................................ 11

Dull red clay, soft and fine grained-....................................................... 12

Brown to yellow shale. ................................................................... 10

Argillaceous limestone, fine, dark laminae.................................................. \

a Gilbert, G. K., Description of the Pueblo quadrangle: Geologic Atlas U". S., folio 36, U. S. Geol. Survey, 1897. 

l> Hills, R. C., Description of the Walsenburg district: Geologic Atlas U. S., Jolio 68, U. S. Geol. Survey, 1900. 

"Lee, Willis T., Jour. Geol., vol. 9, pp. 34S-352: vol. 10, pp. 36-58.
24 ARKANSAS VALLEY IH EASTERN COLORADO.

Morrison Continued. Feet. 

Buff-colored shale.--.-.................................................................. 1J

Argillaceous limestone, fine, dark lamina;.................................................. \

Variegated joint clay.................................................................... 18

Argillaceous limestone, fine grained and hard with contorted lamina?........................... 2

Variegated shales, very soft.............................................................. 30

"Red Beds"?:

Dark shale and gypsum on Red Beds.

Lee gives the following section in Red Rock Canyon, a small side canyon of 

Purgatory River:

Geologic section of Morrison beds in Bed Bock Canyon, Las Animas County, Colo.

"Dakota:" . Feet, 

Massive sandstone. ...___._.,...._._.._...... .. _..__._._.....__._..__.._._....._.._.._..

Morrison:

Brick-red sandy shale, with bands of hard, iine-grained sandstone........................... 25

Reddish limestone, conchoidal fracture................................................... 3-5

Soft, dark, clay shale...................................'...........................:.... 30

Light-brown clay shale,.......................................................;........ 11

Argillaceous limestone.................................................................. j

Brown shale.......................................................................... 7

Concretionary limestone-................................................................ 1

Variegated joint clay................................................................... 7

Yellow paper shale.................................................................... 3

Argillaceous limestone, thin layers..".......................................,.............. J

Fine shale..............................................................:............. ' 1J

White limestone.....................................................:................. 1

Variegated clay shale.................................................................. 15

Argillaceous limestone, thin layers....................................................... |

Yellow shale.......................................................................... 4

Sandstone with agate masses............................................................ 1

Soft, thin-bedded sandstone............................................................. 8

Soft massive sandstone................................................................. 2

Paper shale............................................................................ 2

Soft massive sandstone................................................................ 7

"Rod Beds:"

Gypsum and clay on red sandstone...................................................... 12-20

Tn this canyon the thickness is 132 feet; in Chaquaqua Canyon, 10 miles from 

the mouth of Plum Canyon, it is 175 feet (by barometer), and the predominating 

material is a variegated clay shale popularly termed ' 'joint clay." Lee says:

A subordinate amount of sandstone occurs in places, but there seems to bo no particular horizon at which 

this is likely to be found. In Red Rocks Canyon it occurs at the base; in Plum Canyon none is found; in a 

side gulch east of Plum Canyon a brccciated layer occurs near the top containing angular fragments one-fourth 

inch in diameter; in Chaquaqua Canyon, 4 miles from the mouth of Plum Creek, a coarse, cross-bedded sand- 

 stone layer 15 feet in thickness occurs about 50 feet from the top; just across the canyon from this point, 

perhaps 2 miles distant and at the same horizon, about 30 feet of limestone is found in place of the sandstone. 

In many places the sandstones are friable and composed of 'nearly pure quartz. * * * - The occurrence 

of the limestones, most of which are more or less argillaceous, is as erratic as that of the sandstones. The 

relative amount and position of sandstone, shale, and limestone vary locally.

Dinosaur bones were observed by Mr. Lee in the shales at nearly every horizon, 

but no invertebrates were found. It is reported that the formation is sharply separated from adjoining formations, but without evidence of unconformity by erosion.
U. S. GEOLOGICAL SUfiVEV PROFESSIONAL PAPER NO. 52 PL. XII

A. GREENHORN LIMESTONE NEAR THATCHER, COLO. 

Typical view showing limestone with interbedded black shales. Base of this formation is about 200 feet above water-bearing Dakota sandstone.

B. TIMPAS LIMESTONE IN QUARRY SOUTHEAST OF LA JUNTA, COLO. 

Shows thickness of beds and inteicalations of shale
COMANCHE AND

The gypsiferous shales appear to be distinct, and are regarded as a portion of the 

" Red Beds." The formation extends down Purgatory River to the west line of 

Bent County, where it passes beneath the "Dakota" sandstone. In Muddy Creek 

Valley, in the southern corner of Bent County and the adjoining portion of Las 

Animas County, the Morrison formation is bared of "Dakota" sandstone over an 

area of several square miles in which the same general features are presented as in 

Purgatory Valley. It again appears in Longs Canyon, and the writer found it 

apparently exposed in the Two Butte uplift on Two Butte Creek, where it is thin, 

but consists of gray and purplish clays with layers of light-colored sandstones and 

limestones overlying buff and red sandstones at the top of the "Red Beds." In a 

paper presented to the Geological Society of America, in December, 1902, Mr. Willis 

T. Lee announced that he had traced the formation eastward down the Cimarron 

Valley into Oklahoma. ,

Comanche series. This series was first discovered 3 in Colorado on Two Butte 

Creek, 5 miles east of Two Butte, and during the summer of 1905 Mr. T. W. Stanton 

and Mr. Willis T. Lee found Comanche fossils in the fire clay lying between the two 

sandstones of the " Dakota" in Purgatory Canyon south of La Junta, while later Mr. 

Stanton found them in the same position west of Canyon. This important discovery 

indicates a wide extension of the formation to and along the Rocky Mountain Front 

Range, constituting the middle and lower portions of the "Dakota" formation. 

At the Two Butte Creek locality the creek crosses a.low anticline in which the 

upper member of the " Dakota" sandstone is seen to be underlain by 20 feet or more 

of sandy shales containing numerous Gryphsea corrugata Say, a fossil characteristic 

of the xipper part of the Comanche series. The locality is just above Mechling's 

ranch, in bluffs along the south bank of the creek. Doubtless the Comanche beds 

underlie the greater part of Baea County, for they have been discovered by Mr. 

Willis T. Lee along the Cimarron near the New Mexico-Oklahoma line. Possibly 

they are exposed along Bear and Horse creeks, but these streams have not been 

especially examined for outcrops of beds underlying the top " Dakota" sandstone.

" Dalcota " sandstone. rUnder this heading will be described the entire sandstone 

succession overlying the Morrison formation, for this always has been known as trie 

" Dakota" sandstone or " Dakota" formation. It generally consists of two bodies of 

sandstone, each a hundred feet or more in thickness, separated by a deposit of clay or 

shale from 10 to 15 feet thick. This clay in the Golden region and the top sandstone at various localities have yielded abundant plant remains of the Dakota 

flora (Upper Cretaceous). The tripartite succession strongly suggests the Dakota 

sandstone, Fusoii clay, and Lakota sandstone of the Black Hills, and the -Lower 

Cretaceous age of the two latter, at least in southeastern Colorado, is proved by the 

occurrence of Comanche fossils in the fire-clay member, as described in a preceding 

paragraph.

The "Dakota" sandstone is remarkably uniform in character throughout 

eastern Colorado. The sandstones are mostly hard and .massive, giving rise to a 

well-marked hogback range along the foothills (Pis. V and IX, B] and plateaus, with 

steep-walled canyons in the southeastern part of the State (PI. IV, B). The predominating color is light buff, but some portions are light gray or white, and

oDecsribed by N. H. Darton, in Science, vol. 22, p. 120, 1905.
,26 ARKANSAS VALLEY IN EASTERN COLORADO.

darker tints are not infrequent, especially in the upper bods. Cross-bedding is 

almost general and conglomeratic streaks are frequent, especially at or near the base 

of the lower sandstone. The contact with Morrison beds is abrupt and often presents 

evidence of slight unconformity by erosion. There is often a rapid change to Bonton 

deposits, but in most areas there are a few feet of transition beds consisting of an 

alternation of shales with thin-bedded brown sandstones.*" The lower sandstone 

member is thicker than the upper, often somewhat softer, and it contains shale 

partings at some localities. The middle shale member appears to be present throughout, but generally it is covered by talus. It is well shown in PI. X, A. In the 

Garden of the Gods region Doctor Peale reports a thickness of 257 feet, consisting 

of 200 feet of massive sandstones above, underlain by a finer-grained sandstone, 

in part yellow, containing fragments of Lingula and a lignitic layer with vegetal 

fragments. The writer's measurement in vertical beds near the Gateway gave 

considerably less thickness, and the formation was found to consist of two massive 

beds of sandstone, apparently with a thin series of shales between. The great 

fault cuts off the formation southwest of Colorado Springs, but it appears again in 

the region of Canyon, where Cross describes it as having a thickness of 300 feet and 

as consisting mainly of pure white or gray sandstone, usually friable, of uniform 

texture, with a thin basal conglomerate. Dark shale layers are reported midway in 

the formation in which, in the summer of 1905, T. W. Stanton found Comanche" 

fossils. Fossil loaves are said to occur in thin layers at various horizons.

"Dakota" sandstone is prominent at the foot of Wet Mountains southwest of 

Pueblo, as described by Mr. Gilbert. ° Its greatest measured thickness is 650 feet, 

-near Beulah, where it consists almost entirely of sandstone; elsewhere in the area it 

contains beds of shale and is 300 to 350 feet thick. The basal portion usually is 

conglomeratic, sharply separated from the Morrison clays and the Fountain formation, which it overlaps locally. At the top there is a transition into the Benton 

(Graneros) shales, through an alternation of shale arid thin-bedded, brown sandstones.

In the northern portion of Huerfano County and along the foot of Greenhorn 

Mountain the formation is described by Hills as consisting of 350 feet or more of 

sandstone, of which the lower two-thirds consists generally of a yellowish-gray rock 

of coarse, porous texture, with some layers of fine conglomerate, commonly crossbedded. This lower member is separated from the upper one by gray shales 8 to 10 

feet in thickness. The upper sandstones aggregate 100 to 150 feet in thickness, are 

light gray, and of fresh, fine-grained, close texture, regularly bedded. The formation 

lies'in part on the Morrison, but in places along the mountain front overlaps the 

granites and schists. In the canyons of Cuchara and Huerfano rivers it lies nearly 

level and presents steep canyon walls surmounting slopes of Morrison clay. The 

"Dakota" sandstone is a prominent feature in the foothills extending between 

Spanish Peaks and the Sangre de Cristo Range, appearing for many miles as a vertical 

"stone wall" rising high above the adjoining softer beds.

In the extensive exposures of "Dakota" sandstone in the eastern half of Las 

Animas County is presented a regular succession of the two massive sandstone layers 

with their intervening shales 'or fire clay containing Comanche fossils. Referring

"Gilbert, Q. K., Descriptloh of the Pueblo quadrangle: Geologic Atlas U. S., folio 36, U. S. Geol. Survey, 1897, p. 6.
GRANEBOS AND GREENHORN BEDS. 27

to the formation in Purgatory Canyon, near longitude 104°, Hills states that the 

thickness is about 375 feet, and that the lower two-thirds consists of massive, mostly 

cross-bedded sandstones, with a few shale partings between the beds and more or 

less fine conglomerate. This basal member is overlain by a layer of fire clay, the 

position of which is marked by a narrow shelf due to the projection of the underlying sandstone. The upper sandstone is grayish white, thinner bedded, with more 

numerous shale partings and generally finer grain and more compact than the lower, 

more porous sandstone. These features prevail over the wide area of "Dakota" 

outcrop in southeastern Colorado, in Baca, Prowers, and Bent counties, but with 

many variations of thickness and local details of stratigraphy. In the vicinity of 

the Two Butte uplift the sandstone has been extensively eroded over an area about 

a mile square. The buttes are capped by a thick, massive sandstone (Exeter?), 

which is the upper member of the " Red Beds" and is separated from the "Dakota" 

sandstone by supposed Morrison shales and limestones.

Graneros shale. This shale, which is the basal member of the Benton group, 

underlies a large portion of eastern Colorado. It outcrops in a narrow zone along 

the foothills of the Rocky Mountains and in broader areas on the flanks of the anticlines in Pueblo, Iluerfano, and Las Aiiimas counties, and along the Arkansas 

Valley east of La Junta. Its thickness generally averages 200 feet, and it appears 

to be perfectly conformable to the adjoining formations. Usually there are a few 

feet of transition beds to the "Dakota" sandstone at its base and to the overlying 

Greenhorn limestone. The shale is mostly hard and fissile; its color is bluish gray, 

darkest in the middle and slightly lighter in the upper and lower beds. Thin beds 

of white clay occur locally. In the region south of Pueblo the formation contains 

a layer of limy sandstone 1 to 2 inches thick about 50 feet below .the top of the 

formation. It contains fossil shells of several species. Concretions of carbonate of 

lime occur at various levels in most localities, especially 20 to 30 feet above the base 

of the formation. In some districts this horizon of concretions changes into a layer 

of dark-gray limestone, 8 inches to a foot in thickness, which weathers to a brightorange color. In general the formation appears in gentle slopes of gray clay,,with 

occasional concretions, and in some recently cut banks the shaly character of the 

less weathered material is apparent. In most of the Arkansas Valley region the 

thickness varies only from 200 to 210 feet, but north of Canyon it is between 325 and 

350 feet, and 3 miles south of that city it is 250 feet. The limestone layer occurring 

30 feet above the base of the formation is most conspicuous in the region east and 

northeast of Trinidad, where its thickness is 1 to 2 feet. It is hard and of concretionary structure. It weathers to a bright-orange color, so that it is a conspicuous 

feature.

Greenhorn limestone.^ This medial formation of the Benton group outcrops 

along the margin of the Graneros shale area above described. Its thickness varies 

from 30 to 50 feet. It consists of beds.of pale bluish-gray, fine-grained, compact 

limestone, mostly 3 to 10 inches thick, separated by dark-gray shales 4 to 18 inches 

thick. (PI. XII, A.) These intermediate shale beds are usually thicker where the 

formation is thickest. The limestone has a strong tendency to split with vertical 

cleavage into small slabs one-fourth inch to 2 inches in thickness, which form a conspicuous feature on the slopes. At most localities the formation grades into the
28 ARKANSAS VALLEY JN EASTERN COLORADO.

adjoining formations through a few inches of passage beds. A few thin beds of 

white clay have been reported as occurring in the formation at points in the vicinity 

of Pueblo. Most of the limestone beds contain an abundance of a highly characteristic fossil, Inoceramus labiatus. This form is represented by casts and impressions 

often closely packed together in some of the layers. The appearance of this fossil 

is shown in PI. XIII, B. It is not known to occur in any of the formations. In 

the shales between the limestone layers a somewhat similar fossil occurs, often in 

considerable abundance. In most districts the ledges of Greenhorn limestone give 

rise to low mesas or shelves in the slopes and often bear a scattered growth of 

cedars and pinons. The thickest development of the formation is 2 miles north of 

the city of Canyon, where it is 60 feet thick, while in Webster Park it is not over 10 

feet thick.

Garlile formation. The Carlile formation, which consists mainly of shale, outcrops along the foothills of the Eocky Mountains in the anticlinal area west, south, 

and southeast of Pueblo, along the north side of the Purgatory Valley northeast of 

Alfalfa, and down the north side of the Arkansas Valley below La Junta. Small 

areas occur on divides southeast and southwest of Lamar. The formation consists 

mainly of shale of dark-gray color, averaging 200 feet thick. The middle beds are 

usually -the darkest, some of them being black. At the top there is a bed of sandstone varying in thickness from a few inches to 20 feet, the amount increasing to the 

west. In the same direction, also, the upper fourth of the formation becomes 

somewhat more sandy and occasional thin beds of sandstone appear. In these 

sandy beds occur numerous oval and globular concretions which often attain, a 

diameter of 1 foot to 5 or 6 feet. Most of them are traversed by cracks filled with 

wine-colored calcite. The top sandstone averages 10 to 20 feet in thickness west of 

longitude 104° and attains a maximum of 30 feet at Greenwood on Hardscrabble 

Creek, and near Chandler, south of Canyon. Near La Junta it is 3 feet thick, having 

the relations shown in PI. XV, B. Usually it is soft, somewhat mixed with sandy 

shale and of yellowish color. The fossil known as Pugnellus occurs abundantly 

in the formation in the southwestern portion of the area. At the top of the Carlile 

formation in the southern and central portions of the region to which this report 

relates there is a purplish limestone 6 inches to 2 feet in thickness, in which the large 

coiled shell Prionocyclus Wyoming ensis is of frequent occurrence. From 50 to 75 

feet above the base of the formation in most districts, especially to the east, a thin 

limy layer containing fossils is often found.

Timpas limestone. The Timpas limestone is the lower member of the Niobrara 

group. Its thickness varies from 175 to 200 feet, and it consists of a basal limestone 

with overlying alternations of limestone and shale, all of light color. It is a con-, 

spicuous formation in eastern Colorado, underlying all of the region east of the 

Rocky Mountains, except on the anticlines south and southeast of Pueblo and along 

the Arkansas Valley east of La Junta. In> the region east of Colorado Springs it lies 

deeply buried beneath younger formations, but it appears extensively in the Arkansas Valley and in a broad belt extending across the eastern parts of Huerfano and 

Las Animas counties. A small outlier appears on the high ridge 25 miles southwest 

of Lamar; and there is continuous outcrop of the formation along the north side of 

the Arkansas Valley east of Rocky Ford. At the base of the Timpas there is a lime-
L. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 52 PL. Kill

CHARACTERISTIC FOSSILS OF NIO3RARA AND GREENHORN LIMESTONES. 

A, Ostrea congesta; Z?r Inoceramus labiatus.
NIOBRABA GROUP. , 29

stone series about 50 feet thick, which usually outcrops in a ledge or rocky slope of 

considerable prominence. (PI. XII, B, and XV, B.) It consists of beds in layers, 

mostly 6 inches to a foot in thickness, separated by 1 to 2 inches of light-gray, calcareous, limy shale. The limestone is white, or of a very light-gray color, becoming 

creamy white on weathering. It is compact, fine grained, and has an easy conchoidal 

fracture rudely parallel to the bedding. Owing to the latter property it usually 

weathers into flat flakes 2 or 3 inches long, differing in this respect from the Greenhorn limestone, which cleaves into vertical flakes. The lighter color is also a distinguishing feature. In the eastern portion of the area the rock has a more chalky 

^texture. In the lower beds small nodules of a form of iron sulphide known as 

marcasite occur, which usually weather out as limonite. These are of dark-brown 

color and spherical or cylindrical in shape, usually one-fourth to three-fourths inch. 

in diameter. Tnese often accumulate in considerable number on the weathered 

surfaces. The limestone contains a characteristic fossil known as Inoceramus 

deformis, which occurs scattered at intervals through the beds. The shell is 

thick, has a roughly corrugated surface, and its larger valve has a shallow cup 

shape. Occasionally shells of a small oyster, Ostrea congesta, occur upon it, but 

these are also sometimes found separately. Much of the limestone consists of 

minute organisms known as foraminifera, which are plainly visible when thin slices 

of the rock are examined under the microscope. Above the basal limestone are 

about 100 to 150 fefct of calcareous shale of light-gray color, containing occasional 

thin beds of grayish-white limestone. Toward the top of this member there are two 

or three thicker, persistent layers of limestone, 12 to 18 inches thick, separated 

by a few feet of shales and marking the top of the formation.

Fossils occur in the upper shales, consisting mostly of a very broad, flat Inoceramus, usually covered by Ostrea congesta. In the Pueblo region the lowest stratum 

of the limestone is an impure sandy limestone 1 to 2 feet thick, of dark-gray color, 

which weathers to a yellowish-brown tint. It contains teeth of sharks and other 

fishes and numerous dark pebbles half an inch in diameter.

ApisTiapa formation. In southern Colorado the upper part of the Niobrara 

group has been separated as the Apishapa formation. It consists mainly of shale 

and calcareous shale, with a few layers of cream-colored limestones at the top. The 

thickness varies from 400 to 700 feet, but averages about 450 feet in the greater part 

of the region. Many of the shales vary in color from light gray to dark gray and 

are sandy, with intercalations at intervals of dull-gray to cream-colored limy shales 

and impure limestones. The most persistent lime deposits are an alternation of 

yellow limestones and light bluish-gray limy shales 10 to 20 feet thick, marking the 

top of the formation. The lowest beds are mostly dark fissile shale about 50 feet 

thick. These are followed by about 100 feet of soft, papery shales of dark-gray color. 

The middle portion of the formation is decidedly sandy, while the upper 100 feet of 

the formation, especially in the region between Pueblo and La Junta, consists of 

dark bluish-gray fissile shale, containing two and sometimes three horizons of creamcolored limestone. At various horizons in the formation, especially toward the top 

and eastern part of the district, calcareous concretions occur. They are usually of 

considerable size and of lens shape. In some areas they give place to thin layers of 

concretionary limestone, which are of sufficient hardness to form ledees or low hills in
30 . ARKANSAS VALLEY IK EASTERN" COLORADO.

the smooth slopes of the adjoining beds.. In the region north and east of Trinidad 

the Apishapa formation consists of about 40 feet of dark-gray to blue-gray shales 

at the base, followed by 90 feet of soft, papery shales, which grade upward through 

the blue, sandy shales into alternations of limy and sandy shales. Near the middle 

of the formation these sandy shales become coarser and flag-like, constituting about 

one-third of the formation. This member is usually somewhat bituminous. The 

upper 100 feet resembles the basal portion, but includes two and in places three 

thin layers of limestone and lens-shaped concretions of impure limestone. The 

fossil remains consist of fish scales, which are generally abundant in the shales and 

sometimes in the coarser flag-like layers. Crustacean tracks also sometimes occur.- 

Fish scales from half an inch to an inch in diameter are usually abundant. Portions 

 of the Apishapa beds weather to a bright-straw color, which is a conspicuous feature 

in its outcrops. Ostrea congesta is a characteristic fossil, usually closely packed 

in masses a foot or more in diameter, and is from half an inch to an inch thick 

(PI. XIII, A).

Pierre shale. The calcareous deposits of the Niobrara group are succeeded bya great thickness of the dark-gray Pierre shales. These underlie the deep structural 

basin extending from east of Colorado Springs south to the Arkansas Valley between 

Pueblo and Manzanola, the Florence basin, and the deep syncline in central Huerfano 

and Las Animas counties. Their thickness is over 3,000 feet in the district east of 

Colorado Springs and about Florence, but the amount diminishes to the south and 

is not more than 1,600 feet in the vicinity of Trinidad. In the vicinity of Arkansas 

River below Pueblo several distinct zones have been recognized in the formation. 

The lower beds for a thickness of 400 to 500 feet are of medium-gray color and yield 

no fossils. They contain much selenite in minute flakes. Next above is a zone of 

similar-colored shales containing less selenite and characterized by a.great abundance 

of oval concretions, usually 4 to 8 inches thick and 1 to 2 feet long. These are fine 

grained, dark gray in color, and consist of carbonate of lime and carbonate of iron. 

On weathering these concretions break into small angular fragments of dark rustbrown color, which are often s"o abundant on the slopes as to give them a reddish 

color. On this account the beds have been called the "Rusty zone." Their thickness 

is about 600 feet.' Beginning in the top of this zone and extending upward 100 to 

200 feet is a noticeable abundance of fossils known as Baculites compressus. Their 

form is that of a flattened cylinder, slightly tapering, and sometimes showing the 

remains of the shell. They are often a foot in length and 2 inches in diameter, but 

most of them are smaller. This form occurs at other horizons, but is most abundant 

here. Next above the "Rusty zone" are shales of somewhat lighter color, in the 

upper portion of which occur masses of limestone, often constituting small conical 

hills, or "tepee buttes," as they have been termed (PI. XV, A). These limestone 

masses consist of coarse-textured, gray, fossiliferous rock, often rudely cylindrical 

in form and standing vertical within the shale mass. Ordinarily they are 5 to 30 

feet in diameter and of considerably greater length. As they offer more resistance 

to erosion than m,ost of the adjoining shales, the core and the fragments of rock 

derived from it often rise in conical hills 25 to 50 feet above the surrounding surface. 

Fossils occur in the. limestone in considerable variety, but the most abundant 

species is a small oval bivalve known as Lucina occidentalis. The zone of the tepee
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 52 PL. XIV

VIEW ALONG ARKANSAS RIVER WEST OF PUEBLO. BASAL TIMPAS LIMESTONE ON CARLlLE SANDSTONE.
riERRE SHALE. 31

v

buttes is apparently several hundred feet thick, but its precise stratigraphic limits 

could not be determined. In this zone there also occur smaller lens-shaped limestone, concretions, 6 to 12 inches thick and 1 to 3 feet in diameter, containing large 

numbers of beautifully preserved fossils of various kinds. In many cases the 

original shell is preserved, retaining its original pearly luster. Above the tepee 

zone the shales become darker, are less fossiliferous, and contain fewer "concretions. 

The amount of selenite in small crystals increases considerably. The top of the 

formation is somewhat indefinite, the shales gradually giving place to sandy beds. 

In the region between Walsenburg arid Trinidad the basal and upper zones weather 

to a yellowish-green color; the middle zone is dark gray and lead gray, occasionally 

almost black. The latter zone contains an abundance of lime and iron concretions, 

which break up readily and impart a rusty tint to the surface.

An analysis of a typical sample of topee rock, made by Dr. W. F. Hillebrand," 

of the United States Geological Survey, is as follows:

' Analysis of limestone in tepee core.

Silica (Si02)... .--.---------.----------------------------------------:-------------------- 7.46

Titanium dioxide (TiO2). - .......--...--.------. . ; ------------------------------------ -^ - - - -1 ^ ^

Alumina (A12O3)_ .............................--..---------------------------------------- -J

Iron sesquioxido (Fe2O3) ...............-......--...----.-----..-------.--------------------- .94

Lime (CaO). ................-..-..--.....------.------.---------------------------------- 4G- 98

Magnesia (MgO) .........................-..-..-.------------------.-.-------------------- 2- 36

Potash (K2O) ....:.......-.:.---.--.----------.------------ r ------------------------------ 1 . 

..--..-...--.------------------------------------------------ 7 --------------J '

70

Phosphoric oxide (PA)---.- ---------------.------------------------------------------------ undet.

Carbon dioxide (CO2). ... i .---.---.---.---------------------------------------------------- 39.25

Water loss at 100° C._ ..--..---.--..--.---.------------------------------------------------ -16

Water loss above 100° C. ...................---.-.----------.---.-------------------.-------'

Organic material. ..........................-..............---.-.------..----..-------------.

100. 00

The limestone constituting these tepee cores bears a marine fauna. Lucina 

occidentalis is the most abundant molluscan species, forming a leading constituent 

of the rock. Inoceramus is rather common and cephalopods occur in considerable 

variety. Foraminiferal forms frequently disclose themselves under the microscope. 

The occurrence of fossil wood h'as also been reported from some of the cores. The 

following is a list of the molluscan species determined by T. W. Stanton, from specimens collected by Mr. Gilbert :

Ostrea inornata M. and H.

Inoceramus crispii var. barabini Morton.

Inoceramus vanuxemi M. and H.

Inoceramus sagensis Owen.

Lucina occidentalis var. ventricosa M. and H.

Thclis circularis M. and II.

Anchura (Drepanochilus) americana E. and S.

Nautilus dekayi Morton.

Baculites ovatus Say.

Baculites comprcssus Say.

Scaphites nodosus Owen (?) v 

Scaphites nodosus var. quadrangularis M. and H. .

Scaphites nodosus var-. brevis Meek.

Ptychoceras crassum Whitfield.

ITeteroccras (Exiteloccras) chcycunensc M. and H. (?).

Heteroceras (Didymoceras) nebrascense.

Heteroceras (Didymoceras) cochleatum M. and H. (?).

Heteroceras sp. undet.

Helicoceras sp. undet.

" Gilbert, G. K., Description of Pueblo quadrangle: Geologic Atlas U. S., folio 36, U. S.'Geol. Survey, 1897, p. 7.
32 ARKANSAS VALLEY IN EASTERN COLORADO.

Fox Hills sandstone. The Pierre shale gives place abruptly to several hundred 

feet of sandstone which are supposed to correspond to the Fox Hills formation. 

These sandstones are most extensively exhibited in the region about Walsenburg 

and Trinidad, where they arc of sufficient hardness to give rise to a prominent 

escarpment, extending from the south side of the Huerfano Valley to the Ratoii 

Mesa. In this district they are known as the Trinidad formation, which here 

consists of a lower member, 85 to 90 feet thick, of thin-bedded, fine-grained, darkgray sandstone in layers 2 to 4 inches thick, with thin shale partings, and an upper 

member, 75 to 80 feet thick, of greenish-gray, heavy-bedded, massive sandstone, 

which weathers to a light-gray color. This upper bed is characterized by numerous 

-remains of the fossil Fucoid Jialyntenites, which is easily recognized by the pitted 

cylindrical casts of the branching stems. In the lower beds occasional poorly 

preserved baculites are found. The total thickness of the formation is about 150 

feet in the vicinity of Trinidad and about 170 feet near Walsenburg. At its top 

there are usually a few feet of brown sandstone in contact with the overlying Laramie. 

Near Trinidad the thin sandstone layers of the lower member rarely exceed 3 inches 

in thickness, except near the base, where there is a prominent bed of coarser sandstone 

3 to 5 feet thick. These beds become thicker and coarser northward, and to this 

is due the expansion of the lower zone. In the district east of Colorado Springs 

there is only a small thickness of sandstone between the. supposed top of the Pierre 

shale and the lowest coal beds, so that there the representative of the Fox Hills is 

but scantily developed, unless possibly there should be comprised in it some of the 

underlying shales; -similar conditions prevail in the eastern portion of Elbert County 

and the northern portion of Lincoln County, where the Fox Hills formation has as 

yet not been differentiated. In the Florence basin the formation consists of about 

400 feet of sandy shales, with a few limestone concretions, capped by a persistent 

bed of yellow fossiliferous sandstone 10 to 50 feet thick.

Laramie formation. The Laramie formation occurs in three areas in the district 

to which this report relates. One is in the wide, shallow syncline east of Colorado 

Springs; the second is in a long, deep syncline south and west of Trinidad and 

Walsenburg, and the third is in the deep but small syncline near Florence. The 

rocks are sandstones and shales, and among them at various horizons, especially 

in the lower beds, are extensive deposits of lignite. The sandstones are mostly 

massive, soft, and yellowish, 10 to 20 feet thick, with intervening bodies of shales, 

which are usually sandy and carbonaceous. The thickness varies from 1,000 to 

2,500 feet. The Laramie rocks in the basin east of Colorado Springs have not been 

studied in detail, but in general they present the characteristics above mentioned. 

The coal is worked from lower beds at several points north, east, and southeast 

of the city. The Laramie area extends oast into the northern portion of Lincoln 

County, but its limit in that direction was not accurately ascertained, owing 

mainly to the cover of surficial formations.

In the Florence district the Laramie is composed of a succession of heavy bedded 

sandstones with intercalated shales, and in the lower portions there are beds of 

workable coal. These sandstones form an escarpment surrounding the mesa 

southwest of Florence and constitute one or two small outliers, one of which is 

known as Castle Rock. In this basin there is more sandstone than shale in the 

Laramie formation.
U. 6. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 52 PL. XV

A TEPEE BUTTES IN PIERRE SHALE NORTH OF NEPESTA. COLO. 

The core of these buttes is limestone.

B TIMPAS LIMESTONE ON CARLILE SANDSTONE 2 MILES NORTHWEST OF LA JUNTA, COLO. 

Looking' northwest. The sandstone is behind the figure.
U. fi. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 62 PL. XVI

EXPLANATION

C. Cheyenne Mln.

G. GlenEyri*1

B. Blodgelt Peak

Base of sections is 3OOO feet above sea level 

MAP AND CROSS SECTIONS SHOWING GEOLOGIC RELATIONS IN THE MANITOU EMBAYMENT AND TO NORTH AND SOUTH.
POST-LARAMIE FORMATIONS. 33

In the vicinity of Walsenburg the Laramie formation has a thickness of 1,000 feet, 

which increases to the southward, due to the thickening of the upper member and 

to diminished erosion of its upper surface, until at the State line south of Trinidad 

the thickness is 2,500 feet. The basal beds are shales overlying the Trinidad sandstone. A massive bed of sandstone a hundred feet or so from the base of the formation is'persistent, and'overlies an alternation of arenaceous shale, clay shale, and 

coal. Above this massive sandstone the formation is predominantly sandstone, 

but the sandstones and clay partings vary greatly in thickness. There are two 

principal groups of coal beds one between the Trinidad sandstone and the massive 

sandstone 100 feet above, and the other above this sandsione.

The fossil remains of the Laramie formation are limited to the characteristic 

Ostrea glabra, a unio, and a dinosaur of undetermined genus. It contains a rich 

subtropical flora, similar to the present-day flora of the Gulf States, consisting of 

figs (15 species), oaks, ferns, palms, poplars, willows, and tulips. In the region 

of Golden, Colo., there are 83 species that are peculiar to the Laramie.

CKETACEOUS(I) SYSTEM.

ArapaJioe formation. In the Denver basin the Laramie formation is overlain 

by 600 to 800 feet of conglomerates, sandstones, and shales, which are separated by 

an' unconformity and by some are believed to be of early Tertiary age. At the base 

are 50 to 200' feet of conglomerates and sandstones of increasing coarseness toward 

the mountains, while above are several hundred feet of sandy shales containing 

irregular masses of sandstones. These deposits extend far south of Denver and 

appear to be represented in the Monument Park region and east of Colorado Springs, 

but their limits and relations have not been determined; Apparently the coarser, 

lower beds increase in thickness to the south. The formation appears to be present 

in small amount in the Florence basin, where a series of conglomerates and sandstones 250 to 300 feet thick is supposed to represent it. It is a prominent component in the Spanish Peaks basin, where it is represented by all or part of the Poison 

Canyon formation of R. C. Hills.

Poison Canyon formation. This formation underlies much of the high region 

rising to the Spanish Peaks between the Purgatory and Huerfano valleys. To the 

north it is separated froni1 the underlying Laramie beds by marked unconformity, 

while in the vicinity of Spanish Peaks and southward there appears to have been 

continuous deposition between the two formations. The thickness is 2,000 feet to 

the south and 3,500 feet in the extension of the formation northwestward up the 

Huerfano Valley. The rocks consist of coarse sandstones and conglomerates in 

beds 10 to 50 feet thick, separated by thinner masses of yellow clay. The conglomerates near the middle of the formation often are not firmly cemented and 

resemble gravel beds. The overlying sandstones are light gray, weathering pink, 

while the sandstones lower in the formation are yellowish, with red blotches, but 

similarly weathering to a pink tint. No fossils have been reported, but, from the 

, relations of the formation, there should be little question that it is approximately 

the same age as the Arapahoe. Some baculitcs reported from the section of the

4551 No. 52 06 3
34 ARKANSAS VALLEY IN EASTERN COLORADO.

beds in Poison Canyon doubtless were found in or were derived from the Pierre 

shales, which are overlapped by the formation in that region.

Denver formation. In the Denver basin the Arapahoe formation is overlain by 

several hundred feet of coarse deposits, consisting largely in the lower part of 

debris of younger eruptive rocks and in the upper part_^ of granitic debris. It 

also includes local sheets of basalt and volcanic tuffs. Its age may be early 

Eocene. This formation is not known to extend into the Arkansas basin, but 

may possibly underlie a portion of the high divide near the foot of the mountains. 

Some small areas of conglomerates, sandstones, and shales overlie the supposed 

Arapahoe formation.in the Florence basin, but they can not certainly be correlated 

with the Denver formation. In the higher slopes1 of the Spanish Peaks area, however, there is a formation succeeding the Poison Creek beds which Mr. Hills has 

designated the Cuchara formation, and the stratigraphic succession strongly suggests that this may represent the Denver beds.

Cuchara formation. This formation has a thickness of about 500 feet, consisting mostly of massive, yellowish, reddish, or brownish sandstones, with 50 to 100 

feet of red, brown, and sometimes white marl, shale, and sand at the bottom. The 

sandstone is coarse and the conglomerates are often very loosely cemented, the 

pebbles largely of granite and Carboniferous debris. The formation has yielded 

no fossils, but the Denver formation has yielded 150 species of plants, only 15 of 

which are common to the Laramie.

TERTIARY SYSTEM.

Monument CreeTc formation. On the high divide between the Platte and Arkansas drainage basins, at the foot of the Rocky Mountains, there is an extensive 

deposit of conglomerates, sand, sandstone, gravel, and clay, known as the Monument 

Creek formation. It lies on the Laramie formation to the east and the Arapahoe 

formation to the west, and at Palmer Lake it abuts against the granite at the foot 

of the mountain. There are two members, a lower one of sands and clays and an 

upper one of conglomerate and sandstone. The latter caps numerous buttes and 

plateaus in the high region west and north of Calhan and north of Monument.

Fossil bones of Titanotherium have been discovered by the writer 11 and Mr. C. A. 

Fisher in the upper member in the region north of Calhan and southwest of Elizabeth, which indicate that this portion of the formation is of Oligocene age. The 

lower member may be Oligocene, or perhaps Wasatch or Bridger, in age.

Nussbaum formation. Wide areas of the High Plains adjoining the Arkansas 

Valley in eastern Colorado are mantled by loams, sands, and gravels of late Tertiary age, of wliich some outlying portions westward have been designated the Nussbaum formation by Mr. Gilbert. These deposits consist of the "Tertiary grit" and 

"Plains marl" of the Kansas geologists and are supposed to be of Pliocene age. 

The formation is composed mainly of loose sand and coarse gravel, which on the 

higher divides eastward has a thickness of more than 200 feet. Locally some portions often consist of a loose sandstone, and frequently the beds are cemented 

by carbonate of lime into a very sandy limestone ("mortar beds"), occasionally

" Darton, N. II., Age of Monument Creek formation : Am. Jour. Sci., vol. 20, 1905, pp. 178-180.
QUATERNARY DEPOSITS. 85

of considerable extent.. The most extensive areas cover the High Plains north 

of Arkansas River to the east of Fountain Creek Valley, and south of the river in 

Prowers and Baca counties. Small outliers remain on many of the divides south 

of the river, west from longitude 104° to the foot of the mountains, probably indicating that originally all of the plains region was covered by the formation. In 

general the deposits have a smooth surface and slope gently to the east, but there 

is also a slope into the Arkansas Valley, especially hear Boone and Fowler, where 

it approaches near to the river and ends in a prominent bluff. In Kiowa County 

two distinct terrace levels are exhibited in the slope toward Arkansas River, with 

underlying Cretaceous beds showing in places in the intervening escarpment. 

In the high ridge extending east and north from Calhan the western margin of the 

formation presents a steep front to the west and northwest, in marked contrast 

to the gentle easterly slopes. The eastern limits of the formation north of Arkansas River are usually indefinite, owing to wash of the deposits down the general 

slope. South of Lamar the formation caps an elevated smooth-topped ridge and 

is terminated to the north by'an abrupt slope, especially at the head of Clay Creek. 

To the east it descends rapidly and crosses Two Butte and adjoining creeks.

QUATERNARY SYSTEM.

Alluvium. The largest areas of alluvium in this district are along Arkansas 

River below Pueblo. The width of the bottom lands which they constitute varies 

from three-fourths of a mile to a mile, and the thickness of the deposit is 50 to 60 

feet in the central portion of the valley. The materials are mostly fine sands and 

loams laid down by the river at various stages; in times of flood more or less new 

material is deposited, especially on the lower flats. Above Pueblo, where the river 

flows in a narrower valley, the alluvial flats are narrower.

There are alluvial bottom lands along Fountain Creek and nearly all of the 

larger branches of the Arkansas, the only exceptions being in some of the narrower 

portions of the canyons in the southwestern part of the area. Higher terrace 

levels appear in places, capped by sand and gravel, products of an earlier period 

of Quaternary deposition.

Dune sands, Sands which have been heaped up by the wind occur extensively 

along the south side of Arkansas River from Las Animas eastward, often in a belt 

a mile wide. Dunes of considerable prominence are found south of Lamar and 

Granada. Portions of the Nussbaum formation give rise to sand dunes, notably 

in the region north of Nepesta and in wide areas in Kiowa, Cheyenne, and Lincoln 

counties. Between Rush Creek and Big Sandy nearly all of the land is capped 

by sand dunes derived from the Nussbaum formation.

IGNEOUS ROCKS.

In the Rocky Mountain Range adjoining the Arkansas Valley are extensive 

bodies of igneous rocks, mostly of Tertiary age. Those in the vicinity of Pikes 

Peak and Cripple Creek have been described by Doctor Cross" and others. The 

extensive series of dikes in the Spanish Peaks and adjacent slopes have been

a Cross, Whitman, Description of Pikes Peak quadrangle: Geologic Atlas U. S., folio 7, U. S., Geol. Survey, 1894.
36 ARKANSAS VALLEY IN EASTERN COLORADO.

described by Mr. R. C. Hills'1 and the reader is referred to these publications for 

details." The distribution of the rocks is shown in PI. VI.

The Mesa do Maya and the Eaton Mesa consist of remnants of extensive 

outflows of basalt of late Tertiary or Quaternary age, and in their vicinity are a 

number of similar smaller outliers of the same material, as shown in PI. II. On 

the south side of the Mesa de Maya the basalt is seen to overlie an outlier of later 

Tertiary gravels, which indicates that the age is post-Pliocene.

In the Two Butte uplift igneous rocks appear, as described by Mr. G. K. 

Gilbert, 6 in a laccolithic mass and in numerous dikes.

MANITOU EMBAYMENT.

West of Colorado Springs there is a westward deflection in the Front Range 

of the Rocky Mountains, in which lies a thick development of the Paleozoic rocks. 

The recess is about 4 miles deep and is due to a westward trend of the granite 

on the north side and a profound fault on the southwest side, forming a reentrant 

angle of which the apex is at Manitou. In PI. XVI the principal geologic relations are shown, and they are especially brought out by the central cross section 

on that plate. To the north and south the "Red Beds" usually lie against the 

granite at the surface, but in the embayment the older limestones and sandstones 

appear at the surface. It is probable that east of the mountain front these rocks 

extend far to the north and south, but on either side of the embayment they have 

been eroded from the granite slopes and overlapped by younger sediments. The 

embayment probably was a valley at the time- of this erosion epoch, and the sediments contained in its deeper portion were not removed. Its southwestern margin 

has been cut off by the great fault, which, uplifted the strata so high' that they 

were long ago removed by erosion.

The embayment continues far to the northwest from Manitou, but the strata 

which it formerly contained are removed for the first few miles. A small area 

of "Red Beds" and underlying limestones remains in this area in Manitou Park, 

on Trout Creek, as shown on the geologic map (PI, VI). From the vicinity of 

Manitou northward to beyond Glen Eyrie Creek the basal strata are sandstones and limestones of Cambrian and Ordovician age, and these appear again 

in a small area west of Monument Park. Most of their features were described 

by F. V. Hayden and Dr. A. C. Peale, c and by Prof. W. O.' Crosby/ in a detailed 

account of the Archean-Cambrian contact near Manitou.

The basal bed is a sandstone averaging about 50 feet thick, usually light 

colored and moderately fine grained in its lower beds, and red or pink with greenish 

layers in its upper ones. It contains Cambrian fossils (determined by Mr. Walcott 

as Oltolus (Linguella) similis), anfl more or less glauconite. The sandstone lies on 

the granite along a remarkably smooth plain, which shows occasional local erosion 

irregularities, and the contact is sometimes faulted or flexed. Many details of 

these contact phenomena are described in the paper by Professor Crosby, just

f Hills, R. C., Description of Spanish Peaks, Walsenburg, and Elmoro quadrangles: Geologic Atlas U. 8., folios 71, 08, and 58. 

*> Gilbert, G. K., Laccoliths in southeastern Colorado: Jour. Geol., vol. 4, 1890, pp. 816-82S. _ 

"U. S. Geol. and Geog. Surv. Terr., Seventh Ann. Rcpt., 1874, pp. 193-273. 

1 Bull. Geol. Soc. America, vol. 10, 1S90, pp. 14-164, pis. 14-1S.
U. 6. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 52 PL. XVII

.4, VERTICAL "RED BEDS" NEAR COLORADO CITY, COLO. 

Garden of the Gods to the left; ridge of Niobrara limestone to right. Photograph by I. C. Rus;

B. MORRISON FORMATION ON GRANITES WE: ' _ _ K... __ CK_... 4 INKLES SOUTHWEST OF CANYON, COLO. 

Looking north-north east. The prominent ledge of sandstone is "Dakota,"
MANITOU EMBAYMENT. 37

referred to. Fine exposures may be seen on both sides of Fountain Creek, which 

the formation crosses 1J miles above Manitou, in Williams Canyon, and at Glen 

Eyrie. The formation dips gently to the southwest and extends for some distance 

west up the divides between the valleys above mentioned. It ends abruptly at a 

point a mile north of Glen Eyrie, where it is overlapped by Fountain " Red Beds," 

but reappears for a short distance in a local embayment a mile farther north, and 

Mr. W. T. Lee reports it on Deadman Creek southwest of Monument station.

Overlying the Cambrian sandstone are several hundred feet of limestones, 

of which the lower portion is Manitou, containing Ordovician fossils, while the 

upper members, aecorrlmg to Professor Grabau," contain Mississippian fossils. 

This limestone caps the sloping ridges west and south of Manitou and appears 

extensively in the intervening canyons, especially in Williams Canyon. Its outcrop, 

together with that of the underlying sandstone, is terminated by overlap of the 

Fountain formation, a mile north of Glen Eyrie, and reappears in the small embayment west of Monument Park. In this outlier there are exposed, lying on the 

granite, 30 feet of dark-gray, coarse sandstones, thin bedded and glauconitic at 

the top, overlain by 20 feet of bright-red, sandy limestone with Cambrian fossils, 

and by 50 feet of massive, pure, finej-grained, light-gray limestone. On this limestone, which apparently is Manitou, lies an impure limestone varying from gray 

to buff in color, with a heavy breccia at its base, the latter probably marking an 

unconformity. The limestones are cut off by a fault, bringing down the Morrison 

and overlying "Dakota," but a short distance to the north and south the Fountain 

" Red Beds" are exposed lying directly on the granite.

The Fountain formation occupies a wide area in the Manitou embayment, 

from Glen Eyrie southward. On the west side of the area the dips are low, but 

to the east they become nearly vertical, a feature exhibited in the ledges at and 

near the Gateway to the Garden of the Gods, as shown in PI. IX, A. The rocks 

consist of coarse sandstones, in part conglomeratic and mostly of red color, although 

some portions are mottled with gray. The thickness is 1,000 feet or more. From 

Manitou to Glen Eyrie the formation lies unconformably on the Millsap limestone, 

but no marked divergence of dip or erosion features was observed. To the south 

the formation is cut off by a great fault, which brings it in contact with the granite. 

The outcrop of the formation extends northward from Glen Eyrie, where, as above 

stated, the red grits directly overlap the granite. In places in their northward 

extension they are cut off by faults and extensively overlapped by Tertiary formations. At the top of the formation there is the well-marked Lyons sandstone, 

which gives rise to the prominent white ridge a few rods east of the Gateway to 

the Garden of the Gods. This formation is overlain by the upper "Red Beds," 

which I have designated the Chugwater formation. The latter consists mainly 

of soft red shales with layers of limestone in its lower portion, with a thick bed 

of gypsum at the top. This gypsum bed is 30 feet thick at the Gateway to the 

Garden of the Gods, and for some distance north. Owing to talus, faults, and 

overlaps of younger formations the Chugwater formation is not exposed in the 

region between West Monument Creek and Perry Park, and southeast of Manitou 

it is cut off by the great fault.

a Girty, G. H. Carboniferous formations and faunas of Colorado: Prof. Paper U. S. Geol. Survey No. 16,1903, p.168.
38 ARKANSAS VALLEY IN EASTERN COLORADO.

The formations overlying the Chugwater formation in the Manitou embayment are the. usual succession of Morrison, "Dakota," Benton, Niobrara, and 

Pierise, all of which, except the latter, are cut off by the great fault southwest of 

Colorado Springs. There is also a local interruption in the succession a short 

distance northwest of Colorado City, owing apparently to a short fault cutting off 

the "Dakota" and adjoining beds. The Morrison formation west of Colorado 

Springs exhibits its usual characteristics. Light-colored massive shales predominate, but some fine-grained sandstones and several thin limestone layers are 

included. Portions of the shale are of grayish-green and maroon tints. The 

formation lies directly on the 30-foot bed of gypsum at the top of the Chugwater 

formation. The overlying "Dakota" sandstone varies from 125 to 200 feet in 

greater part, and is in two massive beds, with shales between. As above stated, 

the sandstone disappears for a short distance northwest of Colorado City, probably owing to a local fault. The Graneros shale is 240 feet thick. The Greenhorn limestone is well defined and 75 feet thick, consisting of thin beds of limestone with dark shale alternations and containing large numbers of Inoceramus 

labiatus. The Carlile formation, about 250 feet thick, is terminated by the usual 

bed of sandstone, which is overlain directly by the Timpas limestone. This sand- 

''stone and limestone form a prominent hogback extending from north of Glen Eyrie 

to Bear Creek Canyon, beyond which the Timpas limestone continues nearly to 

Cheyenne Creek, where it is finally cut off by the great fault.

In the region west of Monument Park the Morrison, "Dakota," Benton, and 

Niobrara beds appear at intervals, but they are mostly obscured by talus and 

overlaps. A small exposure of the Timpas limestone appears southwest of Monument station, as shown in PI. XVI. It dips steeply to the east and appears to 

be overlapped by Tertiary formations.

CANYON EMBAYMENT.

General structure. In the region west of Pueblo there is a deep westward 

deflection or reentrant in the Rocky Mountain Front Range, in which the sedimentary strata extend to a short distance west of the city of Canyon. The granite 

Front Range, which is so prominent west of Colorado Springs, exhibits an anticlinal 

structure to the south, and the granite in this anticline pitches beneath the sedimentary strata northeast of Canyon. The sedimentary strata in the syncline on 

its west side extend northward through Garden Park to the north line of Fremont 

County, beyond which the granite rises. The prolongation of the anticline, greatly 

reduced in height, is traceable southward to Huerfano Canyon, crossing Arkansas 

River 6 miles northwest of Pueblo. The syncline deepens to the south, and in the 

region southwest of Florence holds a deep basin of Laramie coal measures. Near 

the south line of Fremont County its western side is faulted so that the Laramie 

sandstones are in contact with the granite. The west and south sides of the Canyon 

embayment consist of the Wet Mountain Range, an anticlinal ridge of granite 

which extends southeastward and finally pitches down near Huerfano River.

In the Canyon embayment are found formations from Cambrian to latest 

Cretaceous or early Tertiary, presenting considerable complexity in overlap and
0. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 52 PL. XV11I

'/Cripple Cree^.

Moriisoii 

r°oco°o°l Red beds 

IIIHII Millsap

Ordovician. 

'/ry^ Granite

Igneous

Faults

SCALE

,___. - 

»Baseot-6ectionsis3000,f<>et77#^^::^

= above sea tev^^n^^^^C^/J^rgt^

MAP AND CROSS SECTIONS OF "DAKOTA" AND ASSOCIATED FORMATIONS IN THE CANYON EMBAYMEIMT,

COLORADO.
, . GARDEN PARK AREA. 39

structural relations. The principal features are shown in PI. XVIII. The relations shown north of latitude 38° 30' arc compiled from the Pikes Peak folio by 

Whitman Cross. The dominant structural features have already been alluded to.

Garden Park area. Oil Creek Valley lies in a syncline pitching southward and 

exhibiting formations of Ordovician, Carboniferous, and Cretaceous ages. On the 

west side of the creek, north of Garden Park, is an extensive area of Ordovician 

limestones and sandstones. At the base is Manitou limestone with a basal cherty 

and quartzitic portion of Cambrian age lying on the granite and gneiss. Next 

follows the Harding sandstone, surmounted by long slopes of Fremont limestone. 

So far as observed, this sequence is general for an extensive area about Garden Park. 

In portions of the area faults cut out some, or all, of the beds. On the granite 

slopes east of the creek numerous small outliers occur. The Manitou limestone is 

100 feet thick and consists of fink-grained, pink or reddish dolomite with Ordovician fossils. Cherty limestone at the base yields fragments of the trilobite Ptychoparia. The Harding limestone consists of fine- and even-grained saccharoidal 

sandstone in alternating beds of light-gray or pinkish and variegated colors, with a 

few bands of dark-red or purplish sandy shale. The maximum thicknesses about 

. 100 feet. The lower part is sometimes calcareous and locally develops into a thin, 

fine-grained dolomite. It is succeeded with apparent conformity by the Fremont 

limestone, which is a bluish-gray or pinkish dolomite of uneven grain, sometimes 

sandy, weathering to very rough surfaces. Its thickness is about 100 feet, and it is 

especially characterized by the occurrence of chain coral (Holysites catenulatus), 

which often occurs in masses 2 feet in diameter. It also contains other fossils of 

later Trenton age.

The Fremont limestone gives rise to long sloping plateaus on the west side of 

Oil Creek north of Garden Park. At the north end of the park the Fremont 

limestone is overlain by Millsap limestone in a narrow outcrop about 1J miles long. 

Thirty feet of the formation are exposed consisting of thinly bedded, variegated, 

dolomitic limestone, with a few thin sandstone layers. Chert nodules in the upper 

limestone layers carry casts of characteristic Mississippian fossils.

The greater part of Garden Park is underlain by the Fountain formation, which 

reaches a thickness of about 1,000 feet. It lies on the Millsap limestone above 

mentioned, but overlaps onto the Fremont limestone, presenting unconformable 

contacts in both cases; for part of its course it is cut off by extensive faults, as 

shown in PI. XVIII. The Fountain beds consist of red sandstone, grits, and conglomerates, heavily bedded and with much feldspathic material derived from the 

adjacent granite. The conglomerate layers contain many pebbles of hard, preCambrian quartzites and of. limestones, quartz, and cherts.

The Morrison formation appears extensively along the south and west sides of 

Garden Park, where the thickness is about 850 feet. It is separated from the Fountain formation by unconformity, but does not present divergence of dip or'evidence 

of deep channeling. The materials are mainly greenish, pink, or gray shales and 

marls. Sandstone occurs at the base and also at numerous horizons in the upper 

part of the section, but the beds vary in thickness and extent. In the sandstone 

deposits about 100 feet from the top of the series, at the locality shown in PI. X, B, 

large numbers of saurian remains have been obtained. Fresh-water shells also occur.
40 ARKANSAS VALLEY IN BASTEKN COLORADO.

Gypsum is locally developed, and a thin limestone occurs in the lower portion of 

the formation.

The Morrisonformation is succeeded in regular order by "Dakota" sandstone, 

which caps high ridges south and west of the park, presenting its usual characteristics and having a thickness of about 300 feet. Southeast of Garden Park lie 

Sixmile, Eightmile, and Cemetery parks, valleys which mark the eastward and 

northeastward extension of the Fountain "Red Beds" across the north end of the 

Front Range anticline. On the north side of these parks are slopes of Ordovician 

limestones and sandstones, comprising Manitou and Harding, with Freriiont as far 

east as Eightmile Creek, northeast of which the Fountain formation lies directly on 

the Harding sandstone. Outliers of Manitou limestone occur at intervals high on 

the granite slopes north. South of the three parks there is a continuation of the 

"Dakota" hogback, with Morrison formation in its northern and northwestern 

slopes. On Eightmile Creek the Fountain and associated formations are traversed 

by a prominent fault which brings up the granite in two prominent knobs on either 

side of the creek. On Wilson Creek, 8 miles northwest of Garden Park, some small 

outliers of Morrison formation lie directly on the granite and gneiss and in part are 

overlapped by small areas oi "Dakota" sandstone. Two similar areas of these two, 

formations occur still farther northwest on the small branch of High Creek. Three 

miles southwest of Garden Park is Shaws Park, underlain by a zone of Fountain 

"Red Beds" outcrops which extend southward to Arkansas River west of Canyon. 

On the west side of this zone the Ordovician limestones and sandstones extend far up 

the mountain slopes, while on the east side is a hogback of Dakota sandstone with 

Morrison formation in its western slope. At the north end of Shaws Park there is a 

prominent fault, which crosses Wilson Creek nearly at right angles and brings formations from Ordovician to Cretaceous into contact with the pre-Cambrian rocks, as 

shown in PI. XVIII.

West of Canyon. In the mountain slopes and hogback west of Canyon there is 

presented the southward extension of the formations of the Garden Park area. The 

formations all dip steeply to the eastward and there are numerous exposures of all the 

beds. The high mountain range west, consisting of granite and gneiss, is traversed 

by Arkansas River in a deep canyon known as the Royal Gorge. On the lower 

eastern slopes of this ridge the Ordovician rocks are extensively exhibited. The 

valley of Sand Creek is in the Fountain "Red Beds." The main hogback west of 

Canyon consists of "Dakota" sandstone, with Morrison fprmation on its west side 

and Benton shales on its east slope. There is also a subordinate hogback of small, 

sharp ridges due to the Timpas limestone of the Niobrara formation. To the east 

there is a broad, deep basin containing Laramie coal measures.

The principal features of distribution of the formations are shown in the middle 

portion of Pl.XVIII. On the mountain road 4^ miles northwest of Canyon the Manitou limestone lies directly on the granite. It is 10 feet thick and contains bands 

of chert. Next above is characteristic Harding sandstone, pink and buff, except 

at the top, where there is a characteristic succession of reddish-shales. The Fremont limestone appears with its usual characteristics, and apparently also the 

Millsap limestone, although no Carboniferous fossils were observed at this place. 

The upper portion of the limestone presents a very irregular contact with conglom-
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 62 PL. XIX

'^m^-^

*r

SHALE MEMBER LYING BETWEEN TOP OF HARDING 

SANDSTONE AND BASE OF FREMONT LIMESTONE ON 

MOU'NTAIN SLOPE NORTHWEST OF CANYON, COLO.

Photograph by C. D. Walcott.

S. HARDING SANDSTONE ON GNEISS AND SCHISTS 1J MILES NORTHWEST OF CANYON, COLO. 

Looking north from below spring west of Harding's quarry. The man's feet are on the contact. Photograph by C. D. Walcott.
OBDOVICIAN WEST OF CANYON 41

erate beds at the base of the Fountain formation A typical exposure of this feature 

is shown in PI XX The conglomerate is about 80 feet thick and is succeeded by 

about 1,000 feet of red sandstones and grits extending to the base of the "Dakota" 

hogback In the vicinity of Harding's quarry, 2 miles northwest of Canyon, the Manitou limestone is seen to have disappeared and it is not found again in the extension 

of the beds southward The following detailed section in this vicinity was made 

by Mr C D Walcott »

Geologic section of Fremont limestone and Harding sandstone near Harding's quarry, northuebt of Canyon, Colo

Fremont limestone Feet 

Compact hard light-gray limestone breaking into ingulai fragments hut with a hnnd <>t puiplf

and gray calcaieo-arenaceous shale at the base, containing a laige Trenton tauna . 45 

Dark, reddish-brown sandstone 10 

Hard, compact, light-colored limestone with fossils 45 

Gray, siliceous, magnesian limestone, somewhat ferruginous m lower portion, weatheis locally to

reddish friable rock, except that near base limestone weathers into rough irreguhi chfts with

many caverns and holes, coials and othei fossils 170 

Red and purple fine-grained, argillaceous, arenaceous shale, fish-plate fragments . . 2-4 

Harding sandstone

Coaise purplish sandstone in several layers with gray layers above . .... 11 

Gray and buff sandston^ j. ... 7 

Fine-grained, aigillaceous, aicnaccous shak . . 3 

Massive giay and reddish sandstone with thin irregular beds ot ieddish-brown, sandy shale m lower

portion, numerous fish remains 20 

Reddish-brown, sandy shales, partly calcareous m some layers, fish plates and other tossiK

abundant 7 

Compact, thinly bedded, reddish and giay sandstone passing into a giay and more massively

bedded, somewhat fnable sandstone that changes at 25 tcet up into a purplish-tinted, somewhat

coarse, friable sandstone, dip 40° . 33 

Coaisc, light-gray sandstone . ... 5 

Gianite

Overlying the Fremont limestone are 15 to 30 feet of impure variegated banded 

limestones, with mterbedded sandstones and argillaceous beds containing Mississippian fossils The unconformity between the two limestones representing Silurian 

and Devonian time is not marked by discordance of dip 1101 by any noticeable eiohion 

features On the north side of Arkansas River, at the mouth of the Royal Gorge, the 

Ordovician beds are well exposed, lying on granite and gneiss and dipping steeply 

eastward There is a basal conglomerate merging upward into hard gray to pink 

sandstones, in part coarse grained, 100 feet or more m thickness These are succeeded by 80 feet of reddish-brown shales and thinly bedded sandstones, 70 feet of 

gray to pink sandstones (mostly soft and massive), 8 feet of red shales, 30 feet of gray 

to pink sandstones (mostly massive), followed by a talus-covered inteival of about 

100 feet, east of which appear ledges of Fiemont, limestone merging upward into a 

few feet of gray sandstone The latter is overlain by the basal conglomerate of the 

Fountain formation On the opposite side of Arkansas Kiver the Ilaidmg sandstone 

is about 200 feet thick and is overlain by about 100 feet of limestones, in part sandy, 

capped by a 20-foot bed of light-gray sandstone On the niegnlar upper surface of 

the latter he coarse conglomerates at the base of the Fountain formation Both the

o^alcott.C D Disco\i,rvof a vertebrate fauna in Ordimcian strata Bull Geol Soc America, vol 3,1892, pp liS-157
42 ARKANSAS VALLEY IN EASTERN COLORADO.

Harding sandstone and the Fremont limestone end a short distance to the south on 

Grape Greek, the sandstone terminating at a point about three-fourths of a mile 

south of Arkansas River. The Fountain formation also thins rapidly, and at a point 

a mile south of the river is only abont 250 feet thick, including a basal red conglomerate. In this vicinity the unconformity at the base of the Morrison is very marked, 

there being much deep channeling in the "Red Beds" surface.

On the east side of Grape Creek, just above its mouth, there are nearly continuous exposures from the granite to the "Dakota" sandstone. At the base are about 

150 feet of massive gray sandstones, pinkish in their upper portion. These are suc- 

"'ceeded by about 50 feet of soft gray sandstone, with some limestone layers, 50 feet of 

limestone (Fremont), 10 feet of red sand and sandstone, about 900 feet of Fountain 

beds (with conglomerate and arkose at the base), and the massive pinkish-gray sandstone 30 feet thick at the top. The latter is a noticeable feature west and northwest 

of Canyon. In a small canyon cut through the hogback ridge 1^ miles south of the 

mouth of Grape Creek there are extensive exposures. On the west there is, first, the 

granite, overlain directly by red and gray conglomerates and grits of the Fountain 

formation, here not over 30 feet thick; then follow Morrison shales about 300 feet in 

thickness, presenting theusual characteristics. The " Dakota" sandstone presents the 

features shown in PI. X, A. It has a lower member, 90 feet thick, of massive buff 

sandstone; a middle member, 100 feet thick, of dark-gray shales 0 with buff sandstone partings, and an upper member, 100 feet thick, of massive buff sandstone 

which rises to the crest of the hogback ridge. The upper portion of this member' 

grades into the Graneros shales through about 15 feet of beds of passage. The 

Graiieros formation is 250 feet thick and is succeeded by 50 feet of typical Greenhorn 

limestone in thin layers with shale partings. Large numbers of Inoceramus labiatus 

occur in the upper portion of the limestone.

The Carlile formation consists of 200 feet of dark shale, with 2j feet of sandy 

limestone with oysters at the top. The basal portion of the Timpas limestone is in 

massive beds 30 feet or more thick, followed by 600 feet of Timpas and Apishapa 

beds. Much shale occurs in the lower and middle portion of the latter, and the usual 

bright-yellow weathered beds at its top. 

The "Dakota" hogback extends southwestward to the granite slopes at the foot 

of the Wet Mountain Range, where all of the strata from the Morrison to the basal 

Pierre are cut off by the east-west fault, as shown in PI. XVIII. Along the main road 

from Canyon to Webster Park, on the hillside above the last big bend in Grape Creek, 

there is a well-marked fault cutting off the "Dakota" sandstone on the west and 

bringing it into contact with two small masses of limestone, apparently Fremont, 

underlain by sandstone, probably Harding, which lies directly on the granite to the 

west. A short distance south of where the road crosses this fault the "Dakota" 

sandstone is seen to be underlain by the Morrison formation, which lies directly on 

granite, showing a definite overlap. This relation is repeated on the west side of 

Grape Creek, as shown in PL XVII, B. In both of these contacts the dips are very 

low, and faulting is out of the question.

Four miles due south of Canyon the Pierre shale appears to extend directly to 

the granite, from which it is apparently separated by the extension of the fault which

o In the summer of 1905 Mr. Stanton discovered Comanchc fossils in these shales.
U- 6. GEOLOGICAL SURVEv PROFESSIONAL PAPER MO 52 PL. XX

CONGLOMERATE AT BASE OF "RED BEDS" LYING UNCONFORMABLY ON MILLSAP LIMESTONE, 4 MILES

NORTH-NORTHWEST OF CANYON, COLO.

Looking northeast.
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 52 PL. XXt

A. TWO BUTTE, IN SOUTHWEST PROWERS COUNTY, COLO. 

Exeter sandstone at top of " Red Beds' uplifted by igneous intrusion.

WATER HOLE IN "DAKOTA" SANDSTONE NEAR THATCHER, COLO.
 RELATIONS SOUTH OF CANYON. 43

cuts off the "Dakota" sandstone and overlying formations along the foot of the 

mountains westward. The fault appears to die out at the point where the main 

mountain slope turns abruptly to the south. In this vicinity the "Dakota" sandstone and overlying formations reappear at first in a steep-dipping monocline with 

Lararnie sandstones less than a mile distant from the granite. At one point 2 miles 

northwest of Chandler the "Dakota" sandstone lies directly on the granite and is 

overlain by 400 feet of Benton shales, including the Greenhorn limestone and 25 

feet of sandstone at the top of the Carlile formation, on which lies the Timpas limestone. West of Chandler a syricline and anticline develop, the latter marked by a 

prominent ridge, which is due to the top sandstone of the Carlile and the overlying 

Timpas limestone. These flexures extend nearly to Oak Creek, where they die out. 

Near the foot of the mountain slope, 2 miles southwest of Chandler, the "Dakota" 

sandstone is underlain by 300 feet of Morrison shale, under which for a short distance 

the Harding sandstone and the Fremont limestone appear. The .following section 

was measured by Mr. C. E. Siebenthal, in beds dipping 80°:

Geologic section 2 miles southwest ofCliandler, Colo.

Feet. 

Morrison shale..--........--.-...--.--...-........----.---...........................-........ 300

Massive white limestone-..._.._.--.........--...___.._...___.._.__._.....___...._..___._._._._ 40

Massive, red, dolomitic limestone............................................................... 40

Red shale and brown sandstone, with .fish scales.................................................t 25

Hard and soft sandstones, interbedded.......................................................... 30

Granite.

A short distance south of this locality a fault develops which cuts off the Morrison, "Dakota," Benton, Niobrara, and Pierre beds in succession and immediately 

south of Oak Creek brings the Lararnie beds into contact with the granite. This 

relation continues to the southern margin of Fremont County, or to a mile south of 

Neulan Creek. At the southern margin of PI. XVIII, which is about a mile south of 

the southern margin of Fremont County, the Pierre shale and granite are in contact 

along this fault line.

EAST SIDE OF GREENHORN MOUNTAIN.

Greenhorn Mountain is a southern extension of the Wet Mountain Range, 

and it terminates southward in a south-pitching anticline, in the same manner as 

the eastern Front Range does northeast of Canyon. Along its east side, from Hardscrabble Creek to its southern termination at Huerf ano River, a considerable variety 

of overlap relations are presented. The principal features are shown in PI. XXII 

(constructed largely from the Walsenburg and Pueblo folios). The lowest beds 

exhibited appear only in small outliers west of Beulah, where a white sandstone 

about 30 feet thick is found, supposed to represent the Harding limestone, lying upon 

gneiss and overlain by limestone supposed to represent the Millsap. Of the limestones 175 feet are exhibited, consisting of gray and purple rocks with some shale, 

especially in the lower part. The limestone is classified as Millsap by the occurrence of 

Spirifer rockymontana, which appears in the middle of the series, but it is possible that 

the lower beds are Ordovician. The Fountain formation appears extensively along 

the valleys of North and South creeks, at the head of Red Creek, and to a limited

/
44 ARKANSAS VALLEY IN EASTERN COL'ORADO.

extent on Hardscrabble Creek. The rocks consist chiefly of brownish-red sandstones, 

mostly of coarse texture and containing a considerable proportion of feldspar grains. 

The upper beds include red and chocolate-brown shale, and at the base there is much 

coarse conglomerate containing pebbles and bowlders of granite and gneiss. Near 

Beulah the strata dip eastward at angles of 10° to 20°; the outcrop has a breadth of 

about 1J miles, and the thickness of the formation is about 2,000 feet. Four miles 

south of Beulah the Fountain formation is cut off by a fault. On the head of Red 

Creek the thickness is much less, and north of Hardscrabble Creek it is in places 

not over 20 feet thick and is occasionally overlapped by the Morrison formation.

At the south end of the Greenhorn Mountain Range, under the Morrison formation, there appear about 200 feet of red sandstones, which have been termed the 

Badito formation by R. C. Hills, who states that it apparently corresponds to part of 

the Fountain formation. The lower half of the formation consists of very coarse 

brownish-red conglomerate, and the upper part is a brick-red sandstone, generally 

massive, but in part thin bedded. The Morrison formation appears at intervals along 

the east side of the Greenhorn Mountain Range, usually lying on the Fountain formation but overlapping the granite on Muddy Creek and near the south end of the mountain. At St. Charles Canyon it is in contact with the granite, apparently because of 

a fault. The rocks are chiefly massive clays of light color, with thin beds of limestone, 

sandstone, and gypsum. The lower beds are mostly white and the upper ones choco^ 

late-brown and maroon. On the slopes of Hogback Mountain the formation consists 

chiefly of red shale with a few layers of hard red sandstone, in all about 70 feet thick. 

Near the southern end of Greenhorn Mountain the Morrison formation is 270 feet 

thick and dips steeply down the mountain slope. The lower beds consist of about 60 

feet of soft white sandstone having a conglomerate layer at the base. "This is followed by hard shaly beds of pinkish and greenish tints, which break into fragments 

with conchoidal fracture. The upper portion consists of variegated shales and clays 

alternating with bands of hard, fine-grained limestone, of ten containing vermilioncolored cherts. One band of conglomerates a few feet thick contains green pebbles. 

At one point the basal sandstone overlaps the Badito formation and rests on the 

gneiss at an angle of 15°. " a

The "Dakota" sandstone extends along the foothills from Adobe Creek to the 

end of the mountain just north of Huerfano River, except for a short distance near 

Muddy Creek, where it is dropped by a fault. To the south it lies directly upon 

the granite, but at St. Charles Canyon and northward it is underlain by older 

sedimentary rocks, and this also is the case at the south end of Greenhorn Mountain. 

On the headwaters of Muddy Creek the formation spreads out extpnsively in a 

shallow basin, as shown in PI. XXII, where it appears lying directly on the granite. 

The outcrop is also of wide extent on St. Charles River and northward to Red Creek. 

In Barton Park the formation occupies a shallow syncline which crosses Hardscrabble Creek near the junction of North and South forks. Just east of this place 

the anticline east of the syncline pitches down and at Greenwood the "Dakota" 

sandstone gives rise to a prominent anticlinal ridge. The formation presents its 

usual features of a light-colored, massive sandstone partly coarse grained, especially in the lower beds, where there is more or less conglomerate; the color is mostly

" Hills, R. C., Description of the Walsenburg quadrangle: Geologic Atlas U. &., lolio 68, U. S. Geological Survey, 

1900, p. 1. .
CAMBRIAN CONDITIONS. 45

pale buff. Considerable shale is included at some localities, especially in the middle 

of the formation. The thickness varies. In the vicinity of Beulah Mr. Gilbert 

reports 650 feet, consisting almost entirely of sandstone. Farther north and south 

the thickness averages about 300 feet. Along the southern slopes of Greenhorn 

Mountain there is included in the lower half of the formation a persistent bed of 

gray shale 8 to 10 feet thick. The upper sandstones, aggregating 100 to 150 feet 

in thickness, are light gray when unweathered, of fine grain, close texture, and 

regular bedding. "The lower two-thirds of the formation consists, as a rule, of 

yellowish-gray sandstone of a coarse, porous texture, and some of the layers are 

really fine conglomerate. Cross-bedding is rather common." a

The Graneros and Carlile formations, with the intervening Greenhorn limestone, extend all along the east side of the range and present no special features of 

stratigraphy or overlap. They are traversed by numerous faults, especially in the 

area between Greenhorn and Rush creeks, as shown in PI. XXII.

GEOLOGIC HISTORY.

The Great Plains region is underlain by sedimentary rocks affording a record 

of physical geography from Cambrian time to the present, but owing to the lack of 

knowledge of the relations of some of the deeply buried rocks and to our imperfect 

interpretation of many features of different geologic epochs, only an outline of the 

general sequence of events can be given. One significant feature is that some of 

the conditions were widespread, for there is remarkable uniformity in the resulting 

products. There were undoubtedly many marine submergences and several periods 

of emergence in which the surface was sculptured by running waters, especially in 

the later epochs.

i Cambrian. During early Cambrian time a large part of west-central United 

States was a land surface. In middle Cambrian time there began the development 

of an interior sea which finally reached the Rocky Mountain province, where it had 

an irregular shore line about a great series of archipelagoes. From the ancient 

crystalline rocks of these shores waves and streams gathered and concentrated 

sands and pebbles, which were deposited as a widespread sheet of sandstone and 

conglomerate on seabeaches, partly in shallow waters offshore and partly in estuaries. In some areas there are exposures in which these sediments, containing 

much local material, may be seen abutting against the irregular surface of the crystalline rocks which formed these shores. The central portion of the Black Hills 

was probably an island in the earlier stages of this period, and, as Mr. Ermnons 

has shown, the Laramie Range and the Rocky Mountain Front Range were for a 

long period highlands rising out of the Cambrian sea. In the northern portion of 

the province thick masses of deposits accumulated as submergence progressed in 

middle Cambrian time, but it is not known that this deposition extended into 

eastern Colorado. The scanty deposits of later Cambrian age appearing near 

Manitbu and Canyon indicate that the waters finally reached the line of the present 

Rocky Mountain Front Range. As these deposits lie in embayments which probably were connected with wider areas of open waters, doubtless there was a wide 

area of later Cambrian deposition eastward under Colorado.

« Hills, R. C., Description of the Walsenburg quadrangle: Geologic Atlas U. S., lolio 68, U. S. Oeol. Survey, 1000, p. 1. .
46 ARKANSAS VALLEY IN EASTERN COLORADO.

Ordovician. Apparently the submergence above described continued with 

similar shore lines through a portion of Ordovician time, for the. later Cambrian 

and earlier Ordovician appear to have about the same limits in the exposures in the 

cmbayments above mentioned. Doubtless to the east of the Rocky Mountain 

front there was extensive deposition of the lime sediments such as 'appear in the 

outcrops, and these may attain considerable thickness under eastern Colorado. 

Except in the embayments, the western shore apparently was located east of the 

extensive "Eed Beds "-granite overlap. Perhaps the deposits originally extended 

farther west all along the slopes and were removed by later erosion along the steeper 

shores, leaving remnants or projections in the embayments where the erosive forces 

were less vigorous.

Silurian-Devonian. From the close of the Ordovician to the time of the early 

Carboniferous sea the uplifts along the western margin of the Great Plains region 

present no geologic record, the Silurian and Devonian being absent throughout. 

This is probably because there was an extensive but very shallow sea, or land so 

low as to leave no noticeable evidence of erosion. Whether it remained land or sea, 

or alternated from one to the other condition, the region shows no evidence of having undergone any considerable uplift or depression until early in Carboniferous 

time, when there was a decided subsidence, which established relatively deep water 

and marine conditions generally throughout the region.

Carboniferous sea. Under the marine conditions of the early Carboniferous 

there were laid down calcareous sediments, which are now represented by several 

hundred feet of nearly pure limestone, exhibited in the Black Hills, the Bighorn 

Mountains, and the Hartville uplift, and, with less thickness, in isolated areas in 

Colorado. Along the Rocky Mountain front in Colorado the Millsap limestone, 

representing the Lower Carboniferous, appears at only a few points, apparently'in 

estuaries which extend west of a general shore line now buried under the Upper Carboniferous sediments by the overlap of the latter on the crystalline rocks. In the later 

part of earlier Carboniferous time there was uplift, resulting in shallower waters, with 

sediments of mixed limy and sandy nature in some portions of the region to the northwest, while along the Front Range, in Colorado,'there was recession of the shore lines 

to an unknown distance eastward, a condition indicated by pronounced unconformity 

at the top' of the Millsap limestone.

During Pennsylvanian or later Carboniferous times the shore line extended 

along the foot of the present Rocky Mountain Front Range, and the coarse red sediments of the " Red Beds " were laid down in part on a granite floor. There were strong 

currents, and possibly at some stages estuaries and swift-flowing streams. Shallow 

waters extended far to the east, and especially to the southeast, but finally the depth 

increased somewhat in these directions,. the coarse deposits giving place in greater 

part to limestones and shales. Limestones also appear to the north in Wyoming and 

southward toward New Mexico, so that the principal area of deposition of the coarser 

shore deposits was between Huerfano River and the Wyoming line. In Permian 

time there was a shallow basin which extended across the western portion of the 

Central Plains region and far to the northwest. In this basin were laid down the 

great mass of red shales of the Chugwater formation, or upper "Red Beds," with 

their extensive interbedded deposits of gypsum, presumably products of an arid cli-
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 62 PL. XXII

ir

?:-:iv.vS-3 'Dakota'

Millsap 

Harding

TJ'- A Granite, gneiss 

Faults

Base of sections is 3000 feet above sea level. Ssft*

MAP AND CROSS SECTIONS SHOWING RELATIONS OF "DAKOTA" AND ASSOCIATED 

FORMATIONS ON EAST SIDE OF WEST MOUNTAINS, COLORADO.
U. S- GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 52 PL. XXIII

01

/ 9 * $ /* Z / ^-3 ^f****- - 

/^ 

.e 5rKfe 1

' "^^

'^Ss^i

Horizontal scale leoo feet 0' e

SECTION SHOWING RELATIONS OF WELLS IN ARKANSAS VALLEY FROM PUEBLO TO COOLIDGE.
GEOLOGIC HISTORY. 47

mate. The sandy clay of this formation accumulated in thin layers, to a thickness 

of 500 to 1,000 feet in Wyoming and the Black Hills, but is much thinner in Colorado. 

There is such uniformity of the deep-red tint that it is undoubtedly the original color, 

and this color is present not only throughout practically the entire outcrop of the 

formation, but also throughout its entire thickness, as is shown by deep borings. It 

is, therefore, not due to later or surface oxidation. This deposition of red mud was 

interrupted from time to time by chemical precipitation of comparatively pure gypsum in beds ranging in thickness from a few inches to 30 feet, often free from mechanical sediment. It is apparent that these beds are the products of evaporation while 

mechanical sedimentation was temporarily suspended, a condition indicative of 

greatly diminished rainfall; otherwise it is difficult to understand their nearly general 

purity. Most of the red deposits were laid down in shallow water, so that there 

must have been subsidence which kept pace with deposition most of the time.

To the southeast, in Kansas and Oklahoma, there was deposited simultaneously 

with the gypsiferous "Red Beds" a part, at least, of the dark shales into which they 

merge. These shales, which are of Permian age, contain thick deposits of salt and 

scattered deposits of gypsum at various horizons. Apparently also to the southeast 

some of the lowest "Red Beds" deposits arc represented by limestones of the lower 

members of the Permian, the products of deeper marine waters. Whether this deposition of the " Red Beds " extended into or through Triassic times in the Central Plains 

region is not known, but evidently it was terminated by uplift which brought the 

region above water. Probably this condition extended through the latter part, if not 

all, of the Triassic and through Jurassic time, during which there was no deposition 

and probably some slight erosion. South of the vicinity of the Wyoming line this 

interval is represented by the general hiatus between the upper " Red Beds" and the 

Morrison deposits.

Cretaceous. East of the Rocky Mountains Morrison sedimentation was in a 

long, relatively narrow trough extending along the west side of the Great Plains. 

This trough was occupied by a shallow body of fresh water which deposited mixtures 

of clay and line sand, with thin, irregular bodies of coarser sand deposited by streams 

or along shores and with occasional thin beds of impure carbonate of lime. Huge 

saurians were numerous, as shown by the frequent occurrence of their remains in 

the deposits, although it is possible that this abundance is due mainly to increased 

mortality or more favorable conditions of preservation, or both.

Morrison time was succeeded abruptly by a change to conditions under which 

coarse-grained, cross-bedded, massive Dakota-Lakota sandstones were deposited. 

Although the deposits change abruptly and there was local channeling of the surface 

of the soft Morrison deposits, the erosion appears to be of remarkably small amount 

and 110 more than would be expected to result from the strong currents bearing 

coarse sands and pebbles.

It is believed that there was no great uplift-erosion interval following Morrison 

deposition, for if there had been the soft deposits would have,been widely removed. 

As it is the Dakota-Lakota sandstones lie on a uniform scries of Morrison sediments from Montana to New Mexico and Oklahoma. It is a significant fact also in 

this connection that some of the saurians of Morrison time appear to have continued 

into the next epoch. In the region in southeast Colorado, western Kansas, and a
48 ARKANSAS VALLEY IN EASTERN COLORADO.

wide area southward, where the Morrison formation is absent, there probably was 

dry land during Morrison time,, but there may have been deposition of more or less 

Morrison sediments which were afterwards removed by erosion in an early Cretaceous uplift. Marine conditions followed, during which the great Comanche series 

was accumulated. Farther north and west in Comanche times there was at first a 

land surface and then shallow waters, in which were deposited the sands now constituting the Lakota sandstone. This was followed by deeper waters, with widespread deposition of the material of the fire clay (Fuson) separating the Lakota and 

Dakota sandstones. Next came a recurrence to conditions similar to those of 

Lakota time, and the Dakota sands were laid down, marking the beginning of 

later Cretaceous time. The Lakota and Dakota sands were derived from various 

sources, probably to the west, and spread by strong currents in two thick deposits 

separated by the interval of invasion of deeper water and cessation of strong currents, in which the widespread intervening fire clay was laid down. The sandstones 

overlap the granites in portions of the region for instance, southwest of Pueblo and 

north of Canyon and there are other places in the granite area from which the sandstones evidently have been but recently removed. These features indicate the position of a portion of the shore lines at least. The extent of the Lakota, as separated 

from the Dakota, not having been ascertained, except that both are present in 

*the Black Hills region and that the Lakota is surely absent in east Nebraska and east 

Kansas, their relative areas of deposition can not yet be indicated. The vast extent 

of this coarse sandstone formation is a wonderful feature, and it is difficult to picture 

the conditions under which it accumulated. The writer formerly thought that there 

might have been a shore line progressing gradually westward, with coarse deposits 

near shore and fine deposits in the deepening waters east, so that the "Dakota" 

sandstone in western Kansas, for instance, might be .represented by shales in central 

Kansas, but as the very characteristic Benton stratigraphy and the " Dakota "- 

Benton relations are 'so uniform over the entire area this hypothesis is untenable.

Following the deposition of this great shoot of sandy sediments there was a 

rapid change to clay deposition, of which the first representative is Benton shale, 

a formation even'more extensive than the underlying "Dakota" sandstone. This 

represents the later Cretaceous submergence, in which marine conditions prevailed, 

and it continued until several thousand feet of clays were deposited, during the 

Benton, the Niobrara, and the Pierre epochs. In Benton times there were occasional deposits of sand and one thin, but very widespread, deposit of carbonate of 

lime the Greenhorn limestone near the middle of the Benton sediments. The 

shale of the Benton is followed by several hundred feet of impure chalk, now constituting the Niobrara formation, and this in turn by many hundred feet of Pierre 

shale, which thickens rapidly to the west, attaining 1,200 feet or more in western 

South Dakota and over 7,000 (?) feet adjacent to the Rocky Mountains in a limited 

area west of Denver.

The retreat of the Cretaceous sea, which corresponds with the Fox Hills epoch, 

resulted in extensive bodies of brackish waters, which spread sands over the clay 

beds, and then of fresh waters, which deposited the sands, clays, and marsh material 

of the Laramie. Apparently these last-mentioned formations were not laid down 

much east of longitude 101°, for they thin rapidly to the east, although, as we do not 

know the extent of post-Laramie erosion, their former limits can only be conjectured.
v°fiGEOLOGIC HISTORY. 49

Post-Laramie conditions. :There was extensive uplift in the Rocky Mountain 

province following Laramie deposition. This fact is clearly indicated in some areas 

in the mountains, where the next succeeding deposits lie on an eroded surface 

having the general outlines of the present configuration, a relation which shows 

that some of the mountain uplifts were truncated and the larger outlines of 

topography established by earlier Eocene time. This erosion was largely effected 

by streams which had strong declivities due to the uplifts. The earliest deposits 

were the coarse beds of the Arapahoe and Poison Creek formations, which mark 

one subperiod of uplift and deposition, the Denver, 'Cuchara, and Huerfano formations marking another. Later, after the outlines of the great mountain ranges to 

the north and west had been carved, there was a long period in which streams of 

moderate declivity flowed across the central Great Plains region. These, with 

frequently varying channels and extensive local lakes, due to damming and the 

sluggish flow of the waters, laid down the widespread mantle of the Oligocene, or 

White River and Monument Creek deposits.. These began with the sands, which 

show clearly the course of old currents by channels filled with coarse sandstone and 

areas of slack water and overflow in which fuller's earth and other clays were laid 

down. The area of deposition of this series extended across eastern Colorado and 

Wyoming and western Nebraska and South Dakota, and probably also farther 

north, for the deposits have been found in western Canada. Doubtless the original 

extent was much wider than the area in which we now find the formation, for 

much has been removed by erosion.

At the beginning of Miocene time the general conditions had not changed 

materially, but doubtless for a while an extensive land surface existed in the Central 

Plains area. To the north the stream channels extended across this surface, and 

running water laid down a widespread sheet of sands derived from the mountains 

to the west. Probably the streams were aided, to a minor extent, by winds. The 

streams of this time shifted their courses across the plains, spreading the debris 

from the mountains in a sheet which in some portions of the- area attained a thickness of 1,000 feet: a flat alluvial fan of wonderful extent. This is the Arikaree 

formation, which buried some of the lower ranges of mountains to the north. It was 

followed by uplift, and by erosion which removed the Arikaree and parts of the 

underlying formations from the south and the east, leaving the thickest mass of the 

deposit in western Nebraska and eastern Wyoming. Probably, however, it never was 

thick nor widespread to the south, erosion predominating in that part of the area 

during deposition to th,e north. Next came the epoch in which the streams began 

depositing the thin mantles of sands of the Ogalalla-Nussbaum and other late Pliocene formations, especially in southern Colorado, southern Nebraska, Kansas, and 

regions farther south. At this time deposition appears to have been mainly in the 

south, erosion probably predominating farther north.

These alternating conditions of later Tertiary deposition and erosion, first in 

the. north and next in the south, were undoubtedly determined by differential uplift, 

the uplifted region suffering erosion and the depressed or stationary region receiving 

deposits from streams which did not have sufficient declivity to carry off their loads. 

This condition also is a feature .of the semiarid climate of the Great Plains, the

4551 No. 52 06 4
U.O

50 ARKANSAS VALLEY IN EASTERN COLORADO.

mountain torrents and resulting vigorous erosion furnishing large amounts of debris, 

which the streams of low declivity and constantly diminishing volume were unable 

to carry to the sea. Even if such a region is traversed by valleys cut during a time 

of uplift or increased rainfall, when cutting ceases these valleys are soon filled by 

sediments, and when they are full the streams, at times of freshet and to a less 

extent in the dry portion of the year, shift their courses so as finally to spread a 

wide mantle of deposits over the entire area in which there is sluggish drainage.

Quaternary. During early Quaternary time there was uplift and floods from 

increased precipitation, causing widespread denudation and trenching of the preceding deposits. The smooth, high plain mantled by the Ogalalla-Nussbaum formations, which originally extended to the foot of the mountains, was deeply trenched 

and widely removed, especially along the Arkansas and Platte valleys. These were 

wide and very shallow at the end of Tertiary time, when the present drainage system 

was outlined, but they were cut deeply in the succeeding uplift and the smaller side 

valleys were then developed. The two large streams east of the mountains have 

since cut their valleys to a low gradient and in times of flood build up their flood 

plains, but the smaller streams are still cutting.

TrNDERGROinSTD WATERS.

In the thick series of sedimentary rocks underlying southeastern Colorado are 

several deposits which contain water. The principal water-bearing formation is 

the "Dakota" sandstone, but waters also occur extensively in the alluvial deposits 

along the valleys, in the sands and gravels mantling parts of the upland east of the 

mountains, and in the sandstones of the Fox Hills, Laramie, and overlying formations. Smaller amounts, mostly of bad quality, occur in the "Red Beds."

"DAKOTA" SANDSTONE WATERS. 

GENERAL CONDITIONS.

Throughout its wide extent in the Great Plains region the "Dakota" and associated sandstones contain water, usually of good quality and under considerable 

pressure. This water passes into the sandstones in their elevated outcrop zone 

along the foot of the mpuntains and in some of the highlands to the south, and flows 

slowly eastward through the permeable sandstone, in most cases finally escaping 

in springs in the areas of low-level outcrop eastward. In the greater part of their' 

area the sandstones lie beneath a mass of impervious shales, which in central-eastern Colorado attain a thickness of several thousand feet. The general structural 

relations of the formation are shown in detail in the cross sections of PI. VII.

As the waters pass underground in high areas they have considerable pressure, 

or "head," under the impermeable strata in the lower lands. In parts of eastern 

Colorado pressures of 20 to 60 pounds are sometimes presented, which can be explained only by the hydrostatic influence of a column of water extending to a high 

altitude in the region west. If it were not for the outflow of the water to the east 

and south the initial head which the waters derive from the high altitude of the 

intake zone would continue under the entire region, but owing to this leakage the 

head is not maintained, and there is a gradual diminution to the east, known as
U. 6. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 52 PL. XXIV

A. ARTESIAN WELL ON RIDGE SOUTH OF LA JUNTA, COLO. 

Depth 750 feet to Dakota sandstone. Not flowing at present.

B. FLOWING WELL AT ROCKY FORD, COLO. 

Flows from a depth of 790 feet from Dakota sandstone.
TJWDEKGKODTtt) WATEKS. 51

Tepee zone.._.

PlEREE. Rusty zone .. __,

Lower beds......

NlOBEAEA .....

Apishapa.

Timpas.

BENTON.

-2000

Carlile.........

Greenhorn ....../

Graneros ......

1 DAKOTA" ..

First Dakota. 

Fireclay ........J

Second "Dakota'

HOERISON .

 RED BEDS"

Dark shale with rusty 

H-1600 concretlons-

\ ~ r i i

Feet

840O

Dark shale with limestone masses.

I2OO

Dark shale.

800

Shales with thin limestones.

400

White limestone.

Dark shales; sandstone 

generally at the top.

Gray limestone. 

Dark shale.

Sandstone. 

Fire clay.

Sandstone.

Clays, light colored.

Red sandstone and 

shale.

FIG. 1. General section showing thickness of strata overlying the " Dakota " sandstone in the Arkansas Valley.
52 ARKANSAS VALLEY IN EASTERN COLORADO.

"hydrostatic grade," a slope sustained by the friction of the water in its passage 

through the strata. In fig. 2 is shown a simple apparatus which illustrates the general conditions.

. Another factor which undoubtedly somewhat influences the hydrostatic grade 

in the Great Plains region is a certain but unknown amount of general leakage 

through the so-called impermeable strata, all of which permit the passage of an 

appreciable proportion of water, especially when under great pressure. From the 

altitudes of outcrops of this sandstone and pressures observed in many wells the 

lines in PI. XXVIII have been constructed to indicate the observed and probable 

head of the artesian waters. In areas of flow the pressure in pounds at any point 

may be ascertained by subtracting the altitude of the land from the altitude of 

head and dividing by 2.3 (the height in feet of a column of water 1 inch square 

weighing 1 pound). In areas too high for flow the depth to the point to which the 

water may be expected to rise may be found by subtracting the altitude of head 

from the altitude of the land. The latter is shown by the brown lines in Pis. VI 

and XXV.

FIG. 2. Diagram of apparatus for illustrating the declivity of head of liquids flowing from a reservoir. The shaded

portions represent water.

FLOWING WELLS.

Rocky Ford. Nearly all of the flowing wells in the Arkansas Valley derive 

their water from the "Dakota" sandstone. There are several artesian wells at 

Rocky Ford which furnish large supplies of excellent water under considerable 

pressure. The depths vary from 767 to 1,033 feet. Wells Nos. 1 and 2 have a 

diameter of 7| inches and a flow of over 100 gallons per minute, with sufficient head 

to rise 80 feet or more above the surface. One of these is shown in PI. XXIV, B. 

The materials penetrated by these wells are indicated in the following record:

Record of artesian well at Rocky Ford, Colo.

Feet. 

Surface materials......................................................................... 0-40

Shale.................................................................................... 40-250

Limestone with salty water at its top.. ....................._........... ..................... 250-290

Shale..................................................................................... 290-605

"Talc vein" .........._................................................._................ 605-008

Shale............... 1.................................................................... 608-690

First sandstone (Dakota) with a flow of soft water............................................ 690-790

These wells begin in the lower part of the Apishapa formation, pass through 

the characteristic limestone bed at the base of the Timpas formation from 250 to
OTEEO COUNTY WELLS. ' 53

290 feet, and penetrate 400 feet of the Benton formation. The latter contains the 

characteristic 3-foot bed of "talc" 100 feet above the top of the "Dakota" sandstone.

An 845-foot well at Wyckoff Park, near Rocky Ford, has a 4-inch bore and a 

flow of 115 gallons a minute.

.The well of the American Beet Sugar Company, sunk by C. H. McVay in 1901, 

had the following record:

Record of artesian well of sugar company at Bocky Ford, C'olo.

Feet.

Surface materials.._.._____.._._.........-...-----...--..----.-..---.---....--.-..-..-... 0-30

Gray shale...........-.......-.-.---------------------------------.--------------------- 30-265

Limestone............ 1 ............................................................ v .... 2G5-312

Black shale, with saltwater at 382 feet.........................1.. ....................'..... 312-700

"Dakota'' sandstone..................................................................... 700-806$

At 793 feet this boring yielded a 50-gallon flpw, which increased to 80 gallons 

at the bottom.

Manzanola. At'Manzanola there is an artesian well which was sunk by the 

town company. Its depth is 1,113 feet, with a diameter of 7| inches, and it yields 

35 to 40 gallons a minute under a pressure of about 55 pounds. The materials 

penetrated by this well are as follows:

Record of first artesian well at Manzanola, Colo.

Feet. 

Surface materials..................................................................... 0- 38

Shale................................................................................ 38- 598

Limestone..............................................................:...........: 598- 633

Shale...:.--.-...-....--..-..-.....-..-..-......-.....-.....--..--..-......-....-.... 633- 933

"Talc vein".......................................................................... 933- 936

Shale..--.........-.....-.....--....--.........-..--.....-.....--.....-....-...-..... 936-1, 033

First sandstone (Dakota)................................. ............................. 1,033-1, 113

The record shows beds of the Apishapa formation, with the typical Timpas 

limestone at a depth of 598 to 633 feet, underlain by 400 feet of the Benton group. 

The latter contains the very distinct bed of hard shale at 933 to 936 feet which the 

well drillers designate the "talc vein," and have recognized in many borings in the 

Arkansas Valley.

In 1903 a well was sunk at Manzanola for the purpose of testing the formations below the "Red Beds" for oil and gas. A depth of 2,110 feet was attained 

without satisfactory results. The pipe has been pulled and the well abandoned. 

The following record has been given:

Record of deep boring at Manzanola, C'olo.

Feet. 

Loam............................................................................... 0 50

Limestone and shales (Niobrara and Benton groups)...................................... 50-1, 050

Sandstone; first "Dakota" artesian flow, 50 gallons............'........................... 1,050-1, 139

Shales....................'........................................................... 1,139-1,239

Sandstone; second "Dakota" artesian flow, 10 gallons..................................... 1,239-1, 375

Gray clays (Morrison formation)........................................................ 1, 375-1, 655

"Red Beds," with several water-bearing strata....................:...................... 1, 655-2, 110
54 v ARKANSAS VALLEY Iff EASTERN- COLORADO.

The water in the "Bed Beds" was too impure for use, and had only pressure 

enough to rise to 700 feet below the surface.

Fowler. The first flowing well below Pueblo is about 2 miles east.,of Fowler, 

on the Atchison, Topeka and Santa Fe Railway. It has a depth of 1,372 feet, at 

which it obtains a flow of soft water from the upper sandstone of the "Dakota" at 

the rate of about one-half gallon a minute. The record of this well is as follows:

Record of artesian well near Fowler, Oolo.

Feet. 

Surface materials...................................................................... 0- 40

Shale......................-..---.....---..-..-.--.-..----.-.----....--.-....-....... 40- 825

Limestone........................................................................... 825- 875

Shale...................^.,-.....-.-....--.-....-----...--.-....--.-....--.-....-.... 875-1,270

First "Dakota" sandstone............................................................. 1, 270-1, 372

This boring begins on the Pierre shale, passes through the Apishapa and Timpas formations of the Niobrara, the limestone at 825 to 875 feet being the characteristic bed at the base of the Timpas, and penetrates 395 feet of the Benton formation 

to the top of the "Dakota" sandstone.

La Junta. In this town there are several wells, formerly flowing, which yield 

soft water that is extensively used by the railroad company and in part for municipal supply. The principal supply is in the second bed of sandstone of the "Dakota" formation, which is entered at a depth of 555 feet. Most of the wells are 

between 405 and 439 feet deep. A boring by the railroad company passed through 

both sandstones of the "Dakota " formation and the underlying shales and sandstone 

into the "Ked Beds," which it penetrated at 1,050 to 1,150 feet. The record of 

this boring is as follows:

Record of deep boring at La Junta, Oolo.

Feet. 

Surface materials..................................................................... ' 0- 37

Gravel....:......................................................'...._................ 37- 48

Shale.............................................................. .^.............. 48- 230

"Talc"................ ........:...........:..-.-...--...........-...-............... 230- 235

Shale and light shale................................................................... 235- 340

"Dakota" sandstone, soft water............ ; ..:........................................ 340- 423

Black shale.......................................................................... 423- 451

Gray sandstone. ....................................................................... 451- 545

Black shale........................................................................... 545- 555

Sandstone; soft water, flows. ........_........._..........._..._.................__.._ . 555- 605

Shale............................................................................... 605- 950

Sandstone; water, no flow...........-..............................................:.. 950-1, 050

Red and variegated shale.............................................................. 1, 050-1,150

This well was plugged at 700 feet and obtains its principal supply of water from 

the second bed of sandstone in the "Dakota" formation at 550 to 605 feet. The 

original flow at 420 feet was 35 gallons a minute, but vigorous pumping has lowered 

the water level many feet and the water is now forced out by air lift. The wells at 

La Junta begin in the Timpas formation, but soon pass into the Benton shale, 

reaching the characteristic "talc vein" at 230 feet and the top of the "Dakota" 

fornlation at 340 feet. This formation presents an alternation of heavy beds of 

sandstone with intercalated shales, and from the record above given may extend to
WELLS NEAR LA JUNTA. 55

a depth of 605 feet. The underlying shales and sandy beds are those which 

outcrop on Purgatory River, 25* miles south of La Junta, lying on the sandstones 

and shales of the "Red Beds," which were entered at a depth of 980 feet in the deep 

boring near La Junta.

Two other wells of the railroad company are 420 and 439 feet deep and are 

pumped by air lift. A well in the McNeen brickyard, with a depth of 405 feet, 

obtained a small flow at 395 feet, which increased to 8 gallons a minute at 405 feet. 

Its diameter is 4J inches-. The well at the flouring mill in La Junta is 425 feet 

deep and flowed 30 to 45 gallons a minute until other wells in the neighborhood were 

pumped, when the flow ceased. It is-now pumped at the rate of 30 gallons a minute, 

but this is not its full capacity. An analysis of the water is given on pages 80, 81.

A well on the hill in the southern part of the town is about 150 feet above the 

railroad depot, and its depth is 750 (or 766) feet. When completed, it flowed 25 

gallons a minute. Now the water rises only to the surface, owing to partial filling 

with sand and possibly to a general reduction of the water level in the vicinity by 

.the several wells near the depot. A view of this well is given in PL XXIV, A.

In 1902 a company was organized to sink a deep well 2J miles south of La Junta 

to test the "Red Beds" and their underlying formations for gas or oil. A depth of 

1,703 feet was reached without obtaining either of these products. Although a 

number of beds of limestone were penetrated in the lower portion of the boring, it is 

probable that they are a part of the "Red Beds" series. The following record has 

been supplied:

Record of deep boring south of La Junta, Oolo.

Feet. 

Soft gray limestone................................................................... 0- 50

Rusty limestone at base of N iobrara .................................................... 50- 60

Dark shales of Benton group _.._.._..__......-..._..................__..__._ __ _..__.:_._ 60- 440

Soft sandstone with artesian flow; first " Dakota"........................................J . 440- ,504

Shales..................".........................-......-.......................,..... 504- 584

Soft sandstone; artesian flow; second "Dakota".......................................... 584- 700

Gray and greenish-gray shales with water at 820 to 120 and 860 to 100 feet (Morrison formation) .. 700- 980 

" Red Beds " with water at intervals which rose to within 200 feet of the surface............. 980-1,703

Some samples forwarded to Washington are as follows:

Samples of borings from La Junta, Colo.

Feet.

Sand and fine-grained sandstone of gray color, with some limestone layers and reddish sandstone.. 1, 230-1, 290 

Red shale, with some limestone layers.................................................... 1, 300-1, 500

Red shale, with some limestone fragments.................... 1.......................... 1, 535

White sand.......................................................................... 1,600

Red shale, with some limestone fragments............................................... 1, 612

Gray limestone and red shale..... 1............................................ j.......... 1, 660

Red shale and gray limestone.......................................................... 1, 703

The Lenox well, in SE. J sec. 2, T. 24 S., R. 56 W., 5 miles west of La Junta, has 

a depth of 740 feet, a diameter of 7f inches, and yields a flow of 12 gallons a minute. 

The well began in Tlmpas limestone, 40 feet above its base, passed through 400 feet 

of Carlile, Greenhorn, and Graneros beds to the top of the "Dakota" sandstone at 

440 feet and penetrated the two sandstones of the "Dakota" for 300 feet. In the 

northeast quarter of the same section, on J. E. Gauger's ranch, there is a similar
56 ARKANSAS VALLEY ~IN EASTERN COLORADO.

well flowing 15 gallons a minute. According to Mr. McVay, the driller, the beds are 

at slightly lower levels, indicating a dip of 27 feet to the mile in that direction.

Holbrook. At this place, which is 9 miles due north of La Junta, in SE. J sec. 27, 

T. 22 S., R. 55 W., there is a well 661 feet deep, which flows about 100 gallons a 

minute. The head of the water is sufficient to raise it 80 feet, or probably much 

more, above the surface, and the flow is about 50 gallons a minute from a 3-inch 

pipe extending to the bottom. The water is soft. No record was obtainable, but it 

is stated that the boring passed through 155 feet of limestone, 385 feet of Benton 

shale with some limestone at a depth of 350 feet, and penetrated 110 feet into the 

"Dakota" sandstone. In the next township east are two shallower wells which 

have flows from the sandstone.

Timpas. -The following report of the well at this place has been furnished:

Record ofloring at Timpas, Colo.

Feet.

Loam.......................-..-.-.--.----------------.----..---------.-..-...-.....--.- 0- 37

Dry gravel............................................................................'... 37-40

Shale..-.--...----.-.--..--.--.----.------.-.--.-.-.----------------.-----.-.-.--.--.--- 40- 85'

Limestone (basal Timpas), some water...................................................... 85-137

Shale, with "talc vein" at 440 to 443 feet=398 feet of Benton.. ................................ 137-538

Sandstone ("Dakota"); poor water at 544 feet, rising to 50 feet; 2-gallon flow at 570 feet........... 538-580

Shale.............,...................................................:.................. 580-605

Sandstone; poor water.................................................................... 005-650

Shale ........'........ .................................................................... 650-656

Gray sandstone.-..........'.-......-..............-.-....-......-.....................'.... 656-716

Sandstone ("Dakota"); 20-gallon flow at 755 feet.....................;....... ............... 716-790

Red shale (Morrison)...................................................................... 790-795

The water which flowed at 755 feet was too highly mineralized to be usable in 

boilers, so that the boring is regarded as a failure. The water flowed into a tank 

27 feet above the ground.

Ayer. This is a siding on the Atchison, Topeka and Santa Fe Railway, 6 miles 

southwest of Timpas, and the record of the well is as follows:

Record of Coring at Ayer, Otero County, Colo.

Feet. 

Surface material.......................................................................... 0-40

Gravel.................................................................................. 40- 43

Gray limestone........................................................................... 43- 80

Black shale, with " talc vein" 147 to 150 feet................................................ 80-249

Sandstone (Dakota); soft water ........................................................... 249-272

Shale.. ..............-.-.-..-..........'................................................. 272-280

Gray sandstone; dry...................................................................... 280-287

Black shale.............................................................................. 287-293

Sandstone; poor water; 25-gallon flow near bottom; 3-gallon flow at 311 feet._._.!.............. 293-343

The water is of unsatisfactory quality, containing 18 grains of sulphate of lime 

to the gallon.

Bloom (Iron Springs'). The.boring at this place, sunk for the Santa Fe Railway, 

had a depth of 1,162 feet and yielded a flow of 5 gallons a minute, with a pressure 

sufficient to raise it 50 feet or more above the surface, but it was abandoned, as the 

water was too hard for use in locomotives. The following record is furnished 
U.S.GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 52 PL.XXVI

EXPLANATION

Areaundei'lajn ay 

"D akota11 sandstones

Outcrop of 

"Dakota" sandstones

-Area imvhich. 

"Dakota"sandstones are absent

ALtitnde of the top of the

*DaVot8L'san-dston© above sealevel

intervallOO feet

Spruncfivlu

B A

MAP SHOWING STRUCTURE OF 

"DAKOTA" SANDSTONE IN EASTERN COLORADO

BY N.H.DARTON 

18O5 

Scale

BlacTccoirtoiirslia-velOOO-footintjervalSjljrolcen. lines l^poftietical
WELLS AT BLOOM AND LAS ANIMAS. 57

Record of boring at Bloom siding, Otero County, Colo.

	Feet. 

Clay.. ............................................................................... 0- 25

Gravel.............................................................................. 25- 31

Shale, with bad water at 76 feet..............................................'. _........ 31- 87'

Gray shale........................................................................... 87- 154

Gray sandstone......_.._...............-.....-....................................... 154- 168

Black shale.......................................................................... . 168- 170

Sandstone, brown above; poor'water................'.................................... 170- 229

Shale........................._.......:.....'.........................._.............. 229- 233

Sandstone; 5-gallon flow of water at 240 feet............................................. 233- 244

Hard sandstone...................................................................... 244- 255

Sandstone; second water at top, first flows 3 to 4 gallons; another flow at 385 feet ........... 255- 400

Red shale (Morrison) ................................................................. 400- 450

White sandstone (Morrison)..................-......-......-.................:........ 450- 455

Red shale........................................................................... 455- 475

Red sandstone....................................................................... 475- 575

Light-gray shale.....................:........................................:........ 575- 695

Light-brown sandstone...'............................................ 1................. 695- 815

Dark-red sandstone................................................................... 815- 880

'Red sandstone.................... ................_............_....._.....,....._... 880- 965

 Red shale........................................................................... 965- 985

Red sandstone....................................................................... 985- 995

" Marble "..............................................1............................ 99*5-1, 000

Red shale.. ......................................................................... 1,000-1,007

Red sandstone; water rose 450 feet; quality bad _.__.__..________._.______..._________._. 1,007-1, 020

White "limestone".......................................... ^........................ 1, 020-1, 025

Red sandstone.................... ^.................................................. 1, 025-1, 085

"Limestone" ......................................................................... 1, 085-1, 087

Red sandstone....................................................................... 1, 087-1,125

"Limestone".. ....................................................................... 1, 125-1, 128

Pink sandstone; water rose 80 feet...................................................... 1, 128-1,133

Red sandstone........................:.............................................. 1, 133-1,140

Red shale. .....................'..................................................... 1, 140-1, 145

White sandstone; water rose 350 feet................................................... 1, 145-1,155

Red shale....................................'............................._.......... 1, 155-1,162

The boring, begins near the base of the Graneros shale of the Benton group 

and passes through various members of the "Dakota" sandstone series into the 

"Red Beds." It was located on the axis of the anticline extending from the south. 

It is difficult to understand why a large supply of water was not obtained from 

the various sandstones which were reported.

Las Animas. The railroad well at Las Animas is relatively shallow, obtaining 

a 20-galloh flow of excellent water from the second sandstone in the "Dakota" 

formation at a depth of 330 feet. The following record is reported:

Record of artesian well at Las Animas, Colo.

Feet.

Surface materials. ................ ..................................'............ .^........ 0-36

Shale..........................................'......-..-....................-............ 36- 90

Sandstone; water at a depth of 90 feet, rising to 10 feet..................................... 90-195

Shale. ...............-.....-.................--..-..------.-.--.-..*-.-.--..----..--..-.. 195-240

Sandstone; flow at 330 feet................................................................ 240-333

Shale...............................................................'..........:........... 333-360
58 ARKANSAS VALLEY IN EASTERN COLORADO.

This well begins in the lower part of the Benton shale and reaches the." Dakota" 

sandstone at a depth of 90 feet, as this formation rises rapidly east of La Junta. 

The second bed of sandstone in the "Dakota" formation begins at 230 feet, with 

the usual intervening mass of shale. (See PI. XXIII.) Other wells in Las Animas 

have depths of 250 and 267 feet and flow 17 and 5 gallons, respectively. A well 

sunk in 1904 on the Cooper place, a mile north of Las Animas, has a depth of 316 

feet and a flow of 10 gallons a minute from a depth of 285 feet. It is cased with 

5f-inch tubing. The pressure is sufficient, it is said, to lift the water 20 feet above 

the surface. The following record has been furnished by John Baugh, the driller:

Record of Cooper well, 1 mile north of Las Animas, Goto.

Feet. 

Surface materials......._....-.............._.-........._....._....._...._................ 0-10

Sand, with water......................................................................... 10-30

Black, sandy shale........................................................................ 30-60

Black shale.............................................................................. 60-70

Sandstone (Dakota), with water to 6 feet....................'.....................'.......... 70-170

Shale, with sandstone layers................................................................ 170-266

Sandstone (second "Dakota"), with main flow at 285 feet..................................... 266-316 '

Twelve miles northeast of Las Animas is the well which was sunk in 1881 by 

the Government under direction of the Department of Agriculture. It was known 

as well No. 1, and is located 7 miles northeast of Fort Lyon. It had a depth of 

815 feet, but obtained only a small amount of water from a depth of 430 feet, which 

flowed at the surface at a rate reported by some persons as 2 gallons a minute, and 

by others as only 3 gallons an hour. The head was stated to be just sufficient to 

raise the water 10 feet above the surface of the ground. This boring cost $18,353; 

the record is as follows:

Record of boring at Fort Lyon, Colo.

	Feet. 

Sand, gravel, and quicksand................................................................ 0- 74

Soft, blue clay....................................................................... t ..... 74- 80

Blue shale............................................................................... 80-86

Gray sandstone-.......................................................................... 86-llfi

Dark shales.............................................................................. 116-120

Streaked sandstone........................................................................ 120-140

Gray, clean grit........................................................................... 140-150

Black, sandy shale........................................................................ ISO-180

Mottled, gray sandstone................................................................... 180-190

Mica sandstone...................................: ....................................... 190-200

Mixed sandy shale, light, very soft.......................................................... 200-225

Mixed sandy shale, dark, very soft.......................................................... 225-250

Black, variegated shale, very soft........................................................... 250-275

Mottled purple shale, soft................................................................... 275-300

Gray shale, soft....I.................................-.-....------------------------------ 300-320

Mottled shales, soft..........'...........................-.........--..-..-.---..--....--.. 320-340

Black shale, soft...,...........-.....-......-...--.--.---------------------------:--------- 340-344

Gray sandstone..........................-....-.-..-....-.----------.------.---------.-.-- 344-355

Coarse sandstone............... 4 ....-......-..---.-------.-------------------.--.-----.--- 355-368

Gray sandstone. -..-......--........-------------.----------------.-----------.--.-------. 368-382

Greenish clay............................................................................. 382-386

Marl..............-...-.--. ...I.......................................................... 386-396

Green and red sandstone, soft..................---.-..-...-----.-...--.-..-...---.......--. 396-439
ABTESIAN WELLS. 59

	Feet. 

Dark-red shale............................................................................ 439-445

Rusty gray sandstone....................................................................... 445-450

Green shale.......................1..........................-.....................:..... 450-460

Green and red shale, soft..._...."..................................................-....... 460-500

Gray sandstone........................................................................... 500-520

Compact gray shale......_..........---....._...-....-....._-..._..-.....__......--..-.... 520-550

Hard shales.... ......................................................................... 550-570

Fine, red sandstone........-.........'.........-......-...-................................ 570-590

Coarse, red sandstone...................................................................... 590-630

Hard, red sandstone; some gypsum......................................................... 630-650

Spotted sandstone........................................................................ 650-662

Mixed sandstones. ........^..:... ^........................................................ 662-703

Red sandstone, massive. -------...--.-------------....-...-...--.........-....-............ 703-751

Soft, red sandstone........................................................................ 751-783

Spotted red sandstone..................................................................... 783-815

The Marlaman well on Horse Creek, 12 miles northwest of Las Animas, has a 

depth of 493 feet, and ax 7-gallon flow from the second " Dakota" sandstone. The 

following record was furnished:

Record of artesian well, 12 miles northwest of Las Animas.

Feet. 

Surface materials......................................................................... 0-30

Limestone and shale..................................................................... 30-230

Dakota sandstone, small flow. ............................................................. 230-330

Shale and sandstone.............. .y ...................................................... 330-443

Second " Dakota " sandstone ............................................................'.. 443-493

Plum Creek. At the Blackwell ranch, on Plum Creek, about 20 miles south of 

Granada, there is a small artesian well which obtains its flow from the "Dakota" 

sandstone at a depth of 155i feet. It is in sec. 1, T. 26 S., R. 44 W. The head 

was found more than sufficient to raise the water to the top of the tubing, 46 

feet above the ground. The volume is 18 gallons or more a minute. This well is 

important as indicating that artesian waters may be expected in the-central and 

east-central portions of the county, at some distance south of the Arkansas Valley. 

Much of this region is occupied by the Greenhorn limestone in the middle of the 

Benton group, so that ordinarily about 250 feet of shales would have to be 

passed through to reach the top of the "Dakota" sandstone, and this formation 

penetrated for a hundred feet or more to obtain a water supply.

Pueblo. The first deep well in the Arkansas Valley was a boring for petroleum 

made at South Pueblo in 1879. At a depth of 1,166 feet a flow of mineral water 

was obtained, amounting to about 100 gallons a minute. The boring was continued 

to a depth of 1,412 feet, and was cased to a depth of 900 feet with 6-inch casing. 

The well has continued to flow with nearly its original volume and a pressure of 60 

pounds to the square inch. The water is not suitable for domestic use, but is the 

basis for the Clark mineral-spring resort, where it is employed for bathing and medicinal purposes. The record of the well is as follows:
60 ARKANSAS VALLEY IN EASTERN COLORADO.

Record of deep well at Glark's mineral spring, Pueblo, Oolo.

Feet.

Soil and gravel........-.-.....---...-.-..--...-.--.---------.---.. ................... 0- 34

Blue shale..--....-..-.---.-..--------------.------------------ "-.-.---------------.-. 34- 58

Black shale.-...----.---.---------.-------------------------------..------------.---. 58- 630

Sand rook, white below............................... .................:............... 630- 690

Black shale.........._...........-..............--....................-............... 690- 700

Soft, coarse sand rock.................................................................. 700- 735

Black shale.......................................................................... 735- 900

Sand rock.......--..---..---...--.------------------------.--.--..-.-------------.--- 900- 940

Black shale.......................................................................... 940-1,030

Sand rock....... ............................................................. i........ 1,030-1,045

Soft black shale............----------------..---------..--.-.-----.------.--.-------.. 1,045-1,148

Sand rock with flow of water........................................................... 1,148-1,180

Black shale. ........................................................................... 1,180-1,195

Coarse sand rock...-..-. .............................................................. 1,195-1,230

Purple shale............................ L .--....--.-......--..--.............--....... 1,230-1,240

Sand rock..........................1 ................................................. 1,240-1,270

Not given............................................................................ 1,270-1, 400

Purple shale.......-...---.--.--.....-... .....;.,...................................'... 1,400

The Colorado Coal and Iron Company has a well on the mesa south of and 

about 100 feet higher than the Clark well. The depth is 1,260 feet, and the flow 

of 20 to 25 gallons a minute is not utilized. An analysis of this water is given on 

pp. 80-81. Another well at Mineral Park in the same vicinity obtains a small flow 

from a depth reported to be 1,150 feet. At the Fariss House, north of the river, in 

Pueblo, a well said to be 1,400 feet deep flows 13 gallons a minute and has a pressure 

of 60 pounds to the square inch. An analysis of this water is given on pp. 80-81.

At the Grand Hotel in Pueblo is a well 1,219 feet deep and 4J inches in diameter 

which has a flow of about 20 gallons a minute of mineral water under a pressure of 

50 pounds to the square inch. At 1,050 feet there was a flow of fresh water under 

a pressure of 15 pounds. An analysis of the water is given on pp. 80-81. OnColumbia 

Heights, a suburb of Pueblo, there is a 789-foot well which found a small flow at 

516 feet, and a second flow at 779 feet in all about 8 gallons a minute.

 Record of well in sec. 9, T. 2i S., R. 65 W., Columbia Heights, Pueblo, Golo.

p ' Feet.

Soil on gravel. ............... r ........................................................... 0- 31

Shale-...--.-.....:..---------..---..-------------..-..------..--.....-...-..-......-.... 31- 90

Limestone.--....-........---..--.---.....---..-...--....--..-.........................-. 90-105

Black slate.-....--------....----.---..--..--------------.------.-.........---.--..--...... 105-516

Sandstone, with water. ___-._--______.-__.-_.-__.___-_._-_.--_____...__.___.-__.__...__..___ 516-616

Black slate..---. .......................................'................................... 616-779

Sandstone, second flow. -....-.....----....--..--..--......--..--... .......'--._.....---.... 779-789

In the adjoining section 17 is a well sunk by C. H. Small, which in 1888 had 

a depth of 772 feet and a small flow. It was deepened later to a second flow. The 

water is similar to that of other wells in the Pueblo region, containing a good deal 

of mineral matter. The following record is given:

Record of artesian well ofC. II. Small, Pueblo, Golo.

Feet.

Black soil........--...-..........--...--..-......---........-..........'.................... 0-12

Blue shale...............:............--.................................................... 12-72

Limestone..............-.......--......-.-..-.---.........................."....'........... 72-82
WELLS NEAK PUEBLO AND FLORENCE. 61

Feet. 

Black shale.....................................................................'......... 82-413

White sandstone.......................................................................... 413-575

Red rock..........................................................'..............'........ 575-7GO

Gray sandstone........................................................................... 760-772

On North Pueblo Heights a well was sunk by a suburban company to a depth 

of 1,820 feet, finding small flows at 1,200 and 1,820 feet. This well is in sec. 12, 

T. 20 S., R. 65 W. A flow of 1£ gallons was reported in 1889. .All the Pueblo wells 

draw their water supply from either the upper or the lower sandstone of the " Dakota " 

formation, but the water is too much mineralized to be of general use. There was 

formerly a well known as McLaiie's, 9 miles west of Pueblo and 4 miles south of 

Arkansas River, on Boggs Flat. It was sunk for oil, but none was found. Water 

was reported at several horizons, but no depths were stated. l

A well on the south side of the river 10 miles west of Pueblo is 795 feet deep 

and has a 30-gallon flow. Sandstone was entered at 535 feet. The water contains 

110 grains of solid matter per gallon.

Florence. Some of the .oil wells in the vicinity of Florence encounter more or 

less water at various depths down to about 1,150 feet. The water is strongly 

mineralized arid often is in large volume. A typical record is reported as follows:

Record ofwdl in sec. 23. T. 19 S., R. 69 W., near Florence, Colo.

» Feet.

Surface materials._......-............_.__._..____._.-__......................_....... 0- 20

Shale and sandy shale; flow of water.................................................... 260- 280

Shale, with layers of limestone.......'................................................... 280- 650

Limestone........................................................................... 650- 695

Sandstone .............'........................................................ ...... 695- 699

White sandstone, second flow.......................................................... 699- 722

Shales, limestone, arid sandstone; very large flow......................................... 722-1,130

Shales and sandstone.................................................................. 1, 300-1, 400

Soft shale...........;................................................................ 1,400-1,600

In 1905 an artesian well was completed 6 miles north of Florence, which is 

reported to have a flow of 360 gallons a minute from a 5f-inch casing. It is located 

in the SW. \ see. 26, T. 18 S., R, 69 W., and has a depth of 1,230 feet. The water 

rises 6 feet above the surface and has sufficient head to rise 80 feet or more. The 

temperature of flow is 87°. Water was found at depths of 230 to 235, 300 to 345, 

and 815 to 900 feet, besides the main flow at 1,210 feet. The record is as follows:

Record ofwdl in SW. J sec. 26, T. 18 S. R. 69 V.

Feet.

Sandy loam,reddish............-..............----.-..---.-......-.-....-..-......... 0- 13

Conglomerate.....!.............'..................................................... 13- 18

Light-blue clay (Pierre)..................................................... 1.......... 18- 210

Light-blue lime.................................................-.---....:............ 210- 250 -

Light-colored sand.................................................................... 250- 255

Shale and limestone,alternating........................................................ 255- 780

Light-colored limestone....................................-.----.---..------......... 780- 810

Light-colored sandstone............................................................... ' 810- 825

Shale, with hard layers, some limestone...._.....__.__..............................__._. 825-1,025

Drab shale........................................................................... 1,025-1,195

Sandstone, with .hard layers.............................--------.-.------------........ 1,195-1,210

"Dakota" sandstone............. ..................................................... 1,210-1,230
62 ARKANSAS VALLEY IN EASTERN COLORADO.

Canyon. Three miles east of Canyon there is a flowing well 900 feet deep which 

appears to derive its flow from a sandy member in the Pierre shale. Another well 

5 miles south, 360 feet deep, has a 'large flow from the same source, or the basal 

Laramie sandstone. A new well at the Sanitarium, 3 miles northeast of Canyon, 

has a depth of 1,670 feet. It is 6 inches in diameter and yields a 300-gallon flow 

under a pressure of about 30 pounds, probably from the "Dakota" sandstone.

Portland. This well is 10 miles south of Portland, on a branch of Ritchie Creek, 

near the south margin of Fremont County. >It flows about 600 gallons a minute 

from a 6-inch casing and has a depth of 1,135 feet. It begins in the upper beds of 

the Apishapa formation, at an altitude of about 5,550 feet, but no reliable record 

could be obtained of the beds penetrated. Probably the Niobrara group has a 

thickness of about 650 feet and the Benton about 415 feet, for it is stated that the 

" Dakota " sandstone was entered at a depth of 1,065 feet. The water contains some 

iron and other salts, but appears to be satisfactory for domestic use and irrigation. 

Two views of this well are given in PI. XXVII, which also show the deep hole washed 

out by the water that escapes along the side of the casing. This well indicates that 

wide areas of flat lands, extending east and north for many miles, are within reach 

of flowing waters which may prove to be valuable in reclaiming the land. Much of 

this area has the fertile, limy soils of the Apishapa formation.

Chandler. A short distance west of Chandler, which lies south of the city of 

Canyon, there is a flowing well 1,075 feet deep sunk in a syncline near the foot of 

the Wet Mountain Range. Its flow is derived from the "Dakota" sandstone and 

is reported to be 80 to 100 gallons a minute. The water is tepid, has a decided iron 

and sulphate taste, and deposits a yellowish-red precipitate on standing. Two 

other wells in the same vicinity yield flows from depths of 487 and 364 feet.

'St. Mary. A 1,670-foot well just east of St. Mary obtains a strong flow from 

Dakota sandstone. The water is " alkaline" and is not used.

NONFLOWING DEEP WELLS.

Ordway. At .Ordway, on the Missouri Pacific Railroad, several wells have been 

sunk which have not succeeded in obtaining a flow. The "Dakota" sandstone was 

penetrated by these and was found to contain an abundance of water, which, however, would not rise higher than to 80 or 90 feet below the surface., The materials 

reported in one of the borings, which has a depth of 1,508 feet, are as follows:

Record of boring at Ordway, Oolo.

Feet. 

Surface materials......................................................................... 0-42

Black shale.............................................................................. 42- 60

Blue and gray shale .........................'............................................. 60- 90

Shale and shells.......................................................................... 90-116

Blue shale- ................................................................................ 116-145

Black shale......................................................----.............'....... 145-185

Sandstone................................................................................ 185-245

Black shale.............................................................................. 245-270

Gray shale............................................................................... 270-345

Limestone, soft-...-....-.................-............................................_.. 345-410

Gray shale, some limestone ................................................................ 410-473
U. S. GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 52 PL. XXVII

ARTESIAN WELL 10 MILES SOUTH OF PORTLAND, COLO. 

Depth about 1,000 feet; flow about 700 gallons a minute from Dakota sandstone,
NON-FLOWING DEEP WELLS. 63

	Feet. 

Gray shale, darker below.............................................................. 473- 580

Black shale........................................................ v ................. 580- 650

Gray shale........................................................................... 650- 700

Shale with shells...................................................................... 700- 710

Shale.......................................;....................................... 710- 765

Brown shale..........................................................'.............--. 765- 785

Light-gray shale. ................................................f .................... 785- 800

Brown shale......................................................................... 800- 825

Shale and limestone layers............................................................. 825- 845

Black shale........................................................................... 845- 855

Shale with limestone layers ............................................................. 855- 925

Limestone and shale...........:...................................................... 925- 960

Limestone........................................................................... 960-1,010

Black shale.................................. A..........................'............ 1,010-1. 325

"Talc "..._......................................................................... 1, 325-1, 327

Black shale.......................................................................... 1, 327-1,410

Sandstone (Dakota) containing some water .....................................:....... 1, 410-1, 500

This boring apparently began in the Pierre shale, passed through the basal 

limestone of the Timpas formation at 960 to 1,010 feet, but either did not penetrate 

sufficiently far into the "Dakota" sandstone to obtain flowing water or more likely 

the altitude of Ordway is too high to afford a flow.

Sugar City. The boring at Sugar City reached a depth of 1,308 feet, but did 

not obtain a flow. This well is reported to have entered the "Dakota" sandstone 

at a depth of 1,230 feet.

Arlington. A. well has been sunk in sec. 13, T. 21 S.., R. 54 W., in the northeast 

corner of Otero County, 10 miles southwest of Arlington and 18 miles due east of 

Ordway. It has a depth of 715 feet, but, although it reached the "Dakota" sandstone, the head was not sufficient to afford a flow, the water level coming only to 60 

feet of the surface. The supply appears to be ample, for the well was pumped 20 

gallons a minute. The following record is given:

Record of well in sec. 13, T. 21 S., R. 54 W., 18 miles due east of Ordway, Otero County, Colo.

	Feet. 

Sand and clay............................................................................ 0-40

Blue shale............................................................................... 40-180

Sandstone. .............................................................................. 180-187

Gray shale............................................................................... 187-227

Limestone. ............................................................................. 227-267

Brown shale.............................................................................. 267-372

Limestone................................................................................ 372-377

Sandy shale.............................................................................. 377-432

Slate.................................................................................... 432-477

Brown shale............................................................................. 477-584

Slate.................................................................................... 584-594

Black sandy shale........................................................................ 594-688

Gray sandstone........................................................................... 688-703

Water-bearing sandstone.................................................................. 703-715

Las Animas. A well was sunk in 1903 in sec. 36, T. 21 S., E. 52 W., 6 miles 

west of the Government well, to a depth of 720 feet. A satisfactory supply of water 

was found in sandstone at 452 to 474 feet, but, as it rose only to within 300 feet of
f>4 ARKANSAS VALLEY IN EASTERN COLORADO.

the surface the well is regarded as a failure. The following record was furnished 

by the owner, Mr. O. G..Scott:

Record of well 8 miles north-northeast of Las Animas, C'olo.

Feet. 

Loam and sandstone. _......,......__..._......_._.................._.__...............___ 0-25

Dark shale-.........:.................................................................... 25-452

Dakota sandstone; water to 300 icet. ..................................................... 452-475

Dry sandstone........................................................................... 475-596

Dark shale. '.. ............................................................................ 596-656

Gray shale with " bowlders" (t).................................................^........... 656-700

"Talc"-..............'................................................................... 700-710

Gray shale lying on red shale............................................................... 710-720

This well began at the top of the Caflile formation and passed through the 

formations of the Bentoii group to the top of "Dakota" sandstone, at 452 feet. The 

sandstone is reported to be 144 feet thick and underlain by 124 feet of Morrison shales 

to the top of the "Red Beds," at a depth of 720 feet.

Gaddoa. At this station, which is on the Atchison, Topeka and Santa Fe Railway, on the river bank, a well has been bored to a depth of 582 feet. The upper bed 

of the "Dakota" sandstone outcrops extensively in this vicinity, and the well reaches 

the lower part of the lower sandstone of the formation. It is 10 miles southeast of 

the Government well described on page 58. The water obtained at 285 feet was 

hard, so that the wells which are now in use obtain their supply from the upper bed 

at a depth of 70 feet, where the water is relatively soft. The following record is 

given:

Record of well at Gaddoa, Colo.

Feet. 

Surface materials.......................................................................... 0-29

Yellow clay........ .'. ......-..:........................................................... 29-33

Sandstone, soft water at 50 feet............................................................ 33- 66

Shale--:.......----'------------.---.............................-.......-................ 66-175

Sandstone, hard water..................................................................... 175-285

Variegated shale, water to 75 feet.......................................................... 285-300

Sand rock, water to 60 feet............................................................... 300-345

Shale.................................................................................... 345-384

White sand rock. .......................................................................... 384-425

Eed shale and sand......................................'................................. 425-492

White slate.............................................................................. 492-582

Lamar. At Lamar there are several wells 226 to 522 feet deep, which furnish 

water for the railroad and the town. Some of them afford a flow, but the head 

is very slight. The well at the railroad tank pumps 80 gallons a minute with the 

pump barrel 200 feet below the surface. Its record is reported as follows:

Record of well at Lamar. Colo.

J . Feet.

Surface materials.......................................................................... 0-34

Shale.................................................................................... 34- 72

" Talc vein ".............................................................................. 72-75

Shale.................................................................................... 75-198

Dakota sandstone; water to 20 i'ect....................................................... 198-265

Shale................................................................................... ; 265-270
NON-FLOWING DEEP WELLS. 65

Feet. 

Sandstone; soft water......___......__................................----....------------ 270-325

Shale.................................................................................... 325-400

Sandstone....................-.......---.............------.;.----........--..-------.--- 400-404

Sandy shale.....................r........................................................ 404-460

Sandstone; soft water, which at 480 feet rises to 60 feet and at 500 feet just flows.....'........- 460-500

Variegated shale red, chocolate, and brown................................................. 500-527

The variegated shales in the bottom of the wejl are probably at the top of 

the Morrison formation. At the waterworks in Lamar a large supply of water 

is pumped from the "Dakota" sandstone at a depth of 300 feet, rising to within 

28 feet of the surface. The water has the composition stated on page 80.

A well 107 feet deep, in the NE. J sec. 36, T. 24 S., R. 47 W., found a large 

supply of water in "Dakota" sandstone. Its diameter is 5 inches and one large 

windmill does not pump it dry. The water is soft, but contains'an appreciable 

amount of salts.

Granada. The railroad well at this place has the following record:

Record of deep well at Granada, Colo.

	Feet. 

Surface materials; hard water.............................................................. 0-36

Shale.......--...............--.-..-.---...--------.-----..-.--..--------..---...-.....-. 36- 58

Limestone yielding bad water.............................................................. 58- 60

Shale.........................------.-..-.....--......-:..--..--......--.......-......... 60- 78

Limestone...........................-.......-........:..................._.............. 78-80

Gray shale............................................................................... 80-195

Black shale.......................................................................1...... 195-323

"Talc vein".. ................................................................ ............ 323-326

-Black shale.............................................................................. 326-353

Sandy shale; some soft water............................................................... 353-405

Dakota sandstone; soft water............................................................... 405-480

Shale......-------.....-----..-----..---------.----..----..------------.......-.---...... 480-497

White clay............................................................................... 497-504

The original water level in the well was about 25 feet below the surface, but 

it is pumped down to below 80 feet, yielding about 80 gallons a minute.

The town well at Granada, drilled in 1904, in the center of the town, has a 

depth of 480 feet, where a large supply of water is obtained. The water is soft 

and rises to within 30 feet of the surface.

Amity. The well at Amity has a depth of 384 feet, reaching the "Dakota" 

sandstone at 310 feet. The water rises to within 19 feet of the surface; the supply 

is very large, and the quality is highly satisfactory. The well is cased with 

100 feet of 7J-inch casing through sand and gravel to the first shale, 187 feet of 

6J-inch casing to shut out some very hard water at a depth of 187 feet, and 380 

feet of 5-inch casing reaching into the "Dakota" sandstone. In one report it is 

stated that the top of the "Dakota" sandstone is at 297 feet, consisting of 4 feet 

of sand lying on shale, and that the second sand with the principal flow was entered 

at 376 feet and penetrated 8 feet. The head of the water in this well is below the 

level of Arkansas River.

Three miles north of Amity, in SE. J sec. 25, T. 22 S., R. 43 W-, there is a deep

well, sunk by the Sugar Beet and Irrigated Land Company in 1902. It is 699

4551 No. 52-
66 ' ARKANSAS VALLEY IN EASTERN COLORADO.

feet deep, 8 to 6 inches in diameter, and yields a large supply of excellent soft 

water, which rises to within 100 feet of the surface. Some water was found at 

300 feet and other depths, but the water utilized is from the bottom of the well. 

The following record of this well was supplied by the company:

Record of well 3 miles north, of Amity, Oolo.

Feet. 

Gravel and sand................... v ...................................................... 0-92

Limestone............................................................................... 92-132

Dark shale............................................................................... 132-610

Dakota sandstone ...................................................................... 610-699

Holly. At Holly there is a well which reaches the "Dakota" sandstone at 

296 feet and obtains a, satisfactory supply of excellent water. At the sugar 

factory, one-half mile west of Holly, a new well 412 feet deep obtains a water 

supply which rises to within 20 feet of the surface. The diminished depth to the 

"Dakota" at"this place indicates that the strata are rising eastward from Granada, 

as shown in the section, PI. XXIII.

Delhi. At a siding on the Santa Fe Railway 8 miles north of Thatcher a well 

was sunk in 1901-2 by the railway company to a depth of 322 feet. The well 

draws water from several beds, from 132 feet down to its bottom. The original 

water level was 50 to 75 feet below the surface, but it has been greatly lowered 

by pumping. With the cylinder at 152 feet it yields 37 gallons a minute. The 

following record was furnished:

Record of well at Delhi, Otero County, Oolo.

	Feet. 

Clay..................................................................................... 0- 75

Dark-gray sand........................................................................... 75-110

Light-gray sand................__........................................................ 110-120

Dark-gray sand, with water at 130 feet...................................................... 120-141

Light-gray sand..............,..........._................................................ 141-161

Dark-gray sand........................................................................... 161-176

Black shale...................I.......................................................... 176-185

Dark-gray sand...... .......-............................:................... ...... 1...... 185-205

Shale..................................................................................... 205-218

White sand.............................................................................. 218-305

Water-bearing beds...........................................................'............ 305-322

This boring begins near the bottom of the Graneros shale and penetrates 

nearly to the bottom of the " Dakota " sandstones. The failure of this well to afford 

a flow is due to outcrop of the sandstones in the depressions west and north.

Tyrone. This is a siding on the Santa Fe Railroad 8 miles south of Thatcher. 

The well was sunk in 1902 by the railroad company to a depth of 580 feet. It 

draws its main supply, which pumps 50 gallons a minute, from a depth of 577 

feet, with the pumping cylinder at 423 feet. The height to which the water rose 

originally is not stated. The following record is furnished:

Record of'well at Tyrone, Las Animas County, Golo.

Feet.

Loam and clay........................................................................... 0-30

Limestone............................................................................... 30- 70

Black shale with bad sulphur water at 175 feet, rising to 70 feet.............................. 70-345

"Talc vein".. ............................................. .^............................. 345-350
NON-FLOWING DEEP WELLS. 67

Feet. 

Black shale. .............................................................................. 350-438

Sandstone (first "Dakota"), with water at 458 feet, which rose to about 375 feet............... 438-480

Black shale............................................................... t .......---- .-. 480-490

Sandstone (second "Dakota"), main water supply... .......................................... 490-577

Black shale.............................................................................. 577-580

This boring begins in the lower portion of the Timpas formation, passing out 

of the Timpas limestone at 70 feet and through 368 feet of beds of the Benton 

group; with characteristic "talc vein" at 345 feet, to the "Dakota" formation 

at a depth of 438 feet. The low head of .the water is due to the low level of "Dakota" 

sandstone outcrops to the west, north, and east.

Trinidad. Several deep borings have been made in and near Trinidad for 

gas, oil, and water, but only water has been obtained. One boring southwest 

of the city is claimed to have reached a depth of 3,000 feet. Two borings in the 

railroad yards have reached depths in excess of 2,600 feet and obtained water 

from the "Dakota" sandstone, which lies at a depth of 2,585 feet. One well, 

reported by the Colorado Southern Railroad Company, has a depth of 2,713 feet; 

at 2,595 feet an abundant supply of excellent water is obtained, which rises to 

within 195 feet of the surface. The well begins about 150 feel below the top of 

the Pierre shale. The following partial record is given:

Record of railroad well at Trinidad, Oolo.

Feet. 

Loam and gravel...................................................................... 0- 42

Gray shale, some water from 150 to 250 feet.............................................. 42-2, 200

Lime shale and black shale with some gas at 2,220 feet.................................... 2, 200-2, 400

Black shale (Graneros) ................................................................ 2, 400-2, 585

"Dakota" sandstones, close and hard................................................... 2,585-2,713

Barela. A well sunk by the Colorado Southern Railroad Company at Barela 

has a depth of 1,340 feet, obtaining water which rises to within 300 feet of the 

surface, and pumps 30 gallons a minute. The following record has been furnished 

by the railroad company:

Becord of well at Barela, Las Animas County, Colo.

Feet. 

Gravel and loam...................................................................... 0- 27

Gray shale.................."...................................................:..... 27- 680

Limestone (Timpas)........ ............-.-.-- -........................................ 680- 704

Black shale........................................................................... 704-1,063

First "Dakota" sandstone............................................................. 1, 063-1, 213

Shale................................................................................ 1,213- ?

Second " Dakota" sandstone. ........... ..................................:............ ? -1, 323

Red rock............................................................................ 1, 323-1,340

This boring began in the Apishapa shales about 100 feet below the top of the 

formation and passed through the basal Timpas limestone at 704 feet. The Benton 

group has a thickness of 359 feet, in which the Greenhorn limestone was not reported. 

The "Dakota" sandstones have a thickness of 260 feet and the underlying "red 

rock" reported is probably in the Morrison formation. The thickness of shale 

between the upper and lower sandstones was not given.

Watervale. A well sunk by the Colorado Southern Railroad Company at 

Watervale, near the southeast corner of Las Animas County, has a depth of 327
68 ARKANSAS VALLEY IN EASTERN COLORADO.

feet. "Dakota" sandstone was found under gray shale at a depth of 100 feet 

and penetrated t'o 285 feet, where red rocks were entered and bored into for 42 feet. 

Water, which rose some distance, was obtained in the "Dakota" sandstone.

Wetmore. In Pueblo County, 1£ miles east of Wetmore, a boring for oil 

reached a depth between 1,300 and 1,400 feet. It penetrated the "Dakota" sandstone for 30 feet. The rock was found to be very hard. Water was encountered, 

which rose to within 100 feet of the surface, which is a high mesa near the foot of 

the mountains. This boring is about a mile south of the flowing well described 

on page 62, but is on land about 450 feet higher. It began in terrace deposits 

capping Pierre shale.

UNSUCCESSFUL DEEP BORINGS.

Cheyenne Wells. The well at this place was bored under the direction of the 

Department of Agriculture more than twenty years ago, by means of an appropriation provided by a special act of Congress. No official data have been obtained 

regarding its depth, record, and results, except the statement that it was unsuccessful. As considerable gas was encountered in its lower portion, a local company 

-was organized to develop a gas supply by a second boring, which reached a depth 

of 1,700 feet and was then abandoned, as the gas was found to be of insufficient 

quantity. Through the kindness of Mr. McLane, of Cheyenne Wells, the following 

record was obtained:

Beeord of boring at Cheyenne Wells, Colo.

Feet. 

Clay......-................-.--.-------------------------------------------...--.... 0- 30

" Magnesia".......................................................................... 30- 60

Sandy gravelly clay. ................................................................... 60- 110

"White sandy clay..................................................................... 110- 130

Soft white sand.._....____..-...................-...-.-.--...---......-.............__ 130- 145

White sandy clay. ................--.....................!'........... ................. 145- 185

Soft white sand....._................................................................. 185- 215

Soft black shale; good water at 257 feet................................................. 215- 534

White sandy shale; gas................................................................ 534-1,260

Chalk rock; brackish water............................................................ 1,260-1,330

Fine sand.....................'...............-...-----.------.----......-.-.......... 1,330-1,360

Soft black shale....................................................................... 1,360-1,460

Soft white sand or limestone........................................................... 1, 460-1, 510

Black shale.......................................................................... 1,510-1,700

(Not given, but thought to be shale).................................................... 1,700-1,770

In this boring a large supply of excellent water was obtained at a depth ,of 

257 feet at the base of the Tertiary formations, but it did not rise far in the casing. 

The record appears to indicate that the Tertiary formations extend to 215 feet, 

but probably they really extend to 257 or 260 feet, where the black shale begins 

in the two shallow wells now in use at the railroad tank. The upper shales are 

undoubtedly Pierre, and the chalk rock at 1,260 to 1,330 is a portion of the Niobrara. 

The supposed limestone at 1,460 to 1,510 feet is probably the Timpas limestone, 

at the base of the Niobrara, and if this is the case the boring stopped in the top of 

the shales not far above the top of the "Dakota" sandstone. It was intended 

that the Government boring should be continued to 2,000 feet, but with the smallsized casing used in its lower portion the bit could not progress below about 1,770
UNSUCCESSFUL DEEP BORINGS. 69

feet. It is unfortunate that the boring was not sunk to the depth intended, as 

there were excellent prospects of reaching the "Dakota" sandstone and obtaining 

water for a pump well. It would thus have thrown most important light on the 

head of the water and prospects in adjoining regions.

Kit Carson. A well bored at Kit Carson in 1870 by the Kansas Pacific Railroad, which attained a depth stated by various authorities as 1,300, 1,460, and 

1,500 feet was also unsuccessful. Doubtless it penetrated practically the same 

beds as those below 300 feet in the Cheyenne Wells boring.

Sheridan Lake. At Sheridan Lake a local company sunk a well to a depth of 

1,280 feet, and found considerable water, but without sufficient head to afford a 

surface flow. The boring is now abandoned. The lowest water in any appreciable 

volume was at a depth of 1,200 feet in a dark-colored sandstone, from which it rose 

to within 40 or 50 feet of the surface. No record is obtainable, but as the boring 

begins in the upper portion of the Niobrara chalk, doubtless the sandstone at 1,200 

feet is "Dakota."

Hoehne. At this station on the Santa Fe Railroad, 9 miles northeast of Trinidad, 

a boring was made to the depth of 936 feet, but, unfortunately, it was abandoned 

before it reached the "Dakota" sandstone, which should there be expected at a 

depth of about 1,100 feet. The boring was begun at the base of the Pierre shale, 

penetrated the Apishapa and Timpas formations, here about 700 feet thick, and 

passed low into the Carlile shale. Doubtless it would have found water in the 

"Dakota" sandstone,.and, as the locality is nearly 300 feet lower than Trinidad, 

it might have obtained a flow. To the north of this place the depth to the '' Dakota " 

beds diminishes as the outcrop zone of the Niobrara formation is crossed, and the 

sandstone comes to the surface a short distance south of Thatcher.

Thatcher. In 1884 a boring was made at this place to a depth of 920 feet. 

It began near the top of the "Dakota" sandstone and penetrated several hundred 

feet into the "Red Beds." Some water was found near the bottom, which rose 

300 feet. No record was obtainable, and neither the quality nor the volume of 

water was stated.

Troy. At a transient settlement by this name, 25 miles north of Watervale, 

a boring 400 to 500 feet deep was sunk several years ago. It began in "Dakota" 

sandstone. No record or other information was obtained, except that it was 

regarded a failure.

Rouse Junction. At Rouse Junction, a station on the Denver and Rio Grande 

Railroad southeast of Walsenburg, the railroad company made a boring to a depth 

of 2,058 feet, but did not find an adequate water supply. A small amount of 

fresh water appeared at 700 and 1,760 feet, and of salt water at 890 feet. These 

waters rose for some distance, but the greatest height was more than 200 feet 

below the surface. The following record was furnished by the railroad company:

Record of well at Bouse Junction, Colo.

feet. 

Shale...................................................................................... 20-800

Coarse white sandstone..................................................................... 800

Black shale; bad water..................................................................... 850

Hard white sandstone...........................'.............................. 1............ 870

Hard rock (reported as granite).............................................................. 930
70 AEKAN3AS VALLEY IN EASTEEN COLOEADO.

	Feet. 

Hard white sandstone.................................................................... 940

Black shales.............I..........--.......-:......--...--.-.-----..--.--.....:--------- 950

Hard white sandstone.....'...................-......---....-............................. 960

Slate........-------------..----.---------------.-------------------:---------...------- 1,010

Shale.---.-..---.------.----------.-------------.------------.--------------.-.-----.--- 1,020

Hard white sandstone and quicksand-.-......._.....--.------.-.---........---....-........ 1,030

Hard white sandstone and quicksand. _.._........_./..___.-.----_---..___..._......--....__. 1,140

Coarse white sand with a little water....................................'................... 1,150

Coarse red sandstone..................................................................... . 1,160

Coarse green sandstone..--..................---.-.---------....------....--........--.... 1,190

Pink slate and sand and "granite"......._____......--..--..-....___.'_ _.................... 1,210

Red sand............................................................................... 1,290

Pink slate............................................................................... 1,320

Drab sand with shells.................................................................... 1, 350

Fine hard white sand..................................................................... 1,380

Fine drab sand and white hard clay........................................................ 1, 390

Red flinty rock. ...................................'....................................... 1,450

Fine gray sand, very hard..-._-_......_.__.__.__.__---.----.--...__..___._,....._..____... 1, 500

Red sand................................................................................ 1, 540

Hard white sand......................................................................... 1,960

Red fine hard sand. ..................................................... .^................. 2,058

This boring was begun near the base of the Pierre shale, and the shales reported 

to a depth of 800 feet are mainly Niobrara and possibly the upper shale of the Benton. The "Dakota" sandstone appears to have been reached at 1,140 feet and 

to have continued to not far below 1,500 feet. The lower 300 feet or more were 

in the "Red Beds" and it was from them that the fresh water at 1,760 feet was 

obtained. The salt water at 890 feet was in sandstone of the Benton group. 

Apparently the "Dakota" sandstone yielded no water, a most discouraging indication, for its capabilities seem to have been thoroughly tested. The explanation 

probably is that, owing to the extensive o.utcrops of the "Dakota" formation, a 

short distance north and east, no head is possessed by whatever water may be 

passing through the sandstone. There is also a likelihood that, the many dikes 

which penetrate the formations near Eouse Junction, particularly to the west, 

may cut off the underground flow.

Walsenburg. At Walsenburg an unsuccessful boring was made sometime 

ago for gas. It was 1,300 feet deep and entirely in the Pierre shale, which here 

has a thickness of about 1,700 feet.

Cuchara. On Cuchara Eiver 7 miles below Walsenburg an 800-foot boring 

was made for coal, oil, or gas. It found an abundant supply of sulphur water, 

which is pumped to the surface. The boring probably reached the top of the 

"Dakota" sandstone.

Elmoro. A 400-foot boring at Elmoro is entirely in Pierre shale and yielded 

no water.

Salt Creek. This place is a siding on the Denver and Eio Grande Eailroad at 

the crossing of Salado Creek, 6 miles south of Eouse Junction. The railroad company made a test boring to a depth of 2,030 feet, which did not find a sufficient 

supply of good water. Analyses of the two principal waters are given on pp. 80-81. 

The following materials were reported, but the record evidently is unreliable:
UNSUCCESSFUL DEEP BORINGS. ' 71

Partial record of deep boring at Salt Creek siding, Las Animus County, Colo.

Feet.

Gravel..............---......---.----------....--...-..---'--....--..--------..--------- 0- , 6

Hard limestone; water at 70 feet rose to 3 feet._...__._..___._.,...................----... 6- 71

Black shale; thin limestone layers......................................................... 71- 250

Sand aud shales; water at 283 feet rose to 140 feet.........................'...........-.... 250- 285

Black and white sand......................................................'..1............ 285- 335

Gray sand.............................................................................. 335- 352

Dark sand............................................................................. 352- 365

Light-gray sand......................................................................... 365- 380

Red sand and hard clay.................................................................. 380- 410

White shale; water at 440 feet rose to 220 feet............................................. 410- 450

Gray hard sandstone..................................................................... 450- 495

Greenish sand and sandstone............................................................. 495- 630

Gray sand................................................................................ 630- 750

Dark-gray sand; water af840 feet rose to 540feet.._..... .^ ............................... 750- 845

White sand............................................ .'............................... 845- 855

Dark-gray sand.......................................................................... 855- 870

Red sand; water at 1,005 feet rose to 705 feet............................................. 870-1 015

Red sand and " granite ".......................................... ....^.................. 1,025

At 1,545 feet water rose to 900 feet, and at 1,800 feet rose to 600 feet.

This boring began in the lower portion of the Pierre shale, penetrated the Niobrara from, about 300 to about 950 feet, and the Benton from about 950 to about 

1,350 feet, where the "Dakota" sandstone was entered. It is the latter formation 

which yields the water at 1,545 feet, a water too highly mineralized to be of any 

use. The lower 200 feet of the well were probably in "Red-Beds." The failure of 

this well to yield a satisfactory water supply is in line with a similar experience 

at Rouse Junction, in the adjoining county to the north. The amount of water at 

Salt Creek was not ascertained, but it was believed not to be great. This and the 

experience of the Rouse Junction well indicate either that the water leaks out to 

the northwest, or that its circulation is impeded by the many dikes of igneous 

rock which intersect the formations in the surroxmding region. This diminished 

circulation is also indicated by the salinity of the water, which we should expect 

would be greatly decreased if there were a free underground passage to the 

canyons north and east; moreover, in these canyons very little water is seen to 

come out of the formation.

Boone. In 1903 a deep boring was made at Boone to explore for oil or gas. It 

reached the top of the "Dakota" sandstone, which was not penetrated sufficiently 

to afford a water supply. The following record is furnished:

Record of boring at Boone, Colo.

Feet. 

Surface materials..................................................................... 0- . 25

Shale........................ f ... .................................................... 25-1,560

Limestone-.......................................................................... 1, 560-1, 610

Shale................................................................................ 1, 610-1.720

Limestone .......................................................................... 1, 720-1, 740

Shale with " talc vein "................................................................. 1, 740-2, 200

"Dakota"sandstone.................................................................. 2,200-

The first 1,000 feet of shale probably are of the Pierre, while the Niobrara, 

with its Apishapa shales above and Timpas limestone below, extends to 1,740 feet, a
72 ' ARKANSAS VALLEY IN EASTERN COLOBADO.

thickness of about 740 feet. The Carlile, Greenhorn, and Graneros beds comprise 

a thickness of 460 feet., This boring is near the axis of a deep north-pitching syncline a fact which accounts for the great thickness of Pierre shale.

Pueblo. In 1903 two deep borings were sunk in north-central Pueblo County, 

with the hope of finding oil or gas, but without success. Both borings are situated 

north of Arkansas Elver one 1,900 feet deep, 7 miles northeast of Pueblo, and 

the other 2,655 feet deep, 10 miles northeast of Pueblo. The shallower boring 

appears not to have reached the "Dakota" sandstone,, but found some water 

which rose to within 550 feet of the surface. The 2,655-foot well penetrated the 

"Dakota" sandstone 55 feet and found water which rose 1,000 feet or more. The 

following records were furnished:

Records of wells 7 and 10 miles northeast of Pueblo, Colo.

Well No. 1: '' Feet.

Shale............-........----.--------..--------------.---..--............-...... 0-1,400

Limestone.. ...................... .^........:.. : . .'.'.'. .......'.'.'.__.".'.............'... " 1,400

Sandstone........................................................................ 1,440

Shale--.-........-....---.-------.-.--...--..-----------.-.-...---...-......-.... (?) 1,875

Sandstone (probably Carlile)........................................................ 1, 875-1,900

Well No. 2:

Shale.......---:--,-...---------------.-----.----.-------------.---...--------... 0-2,000

Limestone.. ...................................................................... 2,000-2,100

Sandstone (Carlile)................................................................. 2,100-2,140

Shale...........'................................................................. 2, 140-2, 600

"Dakota" sandstone........... 1.................................................. 2, 600-2, 655

The altitude of the first well is about 4,900 feet and its precise location is 4£ 

miles north and a half mile west of Baxter siding, on the Missouri Pacific Railroad. 

The other boring is at an altitude of 4,750 feet and its approximate location is 6 

miles north and 3 miles west of Nyburg siding, on the Missouri Pacific Railroad. It 

is probable that if the "Dakota" sandstone had been more deeply penetrated by 

this boring the water would have risen to within 100 feet of the surface, but the boring 

is situated on land too high for artesian flow.

Colorado City. Deep borings at Colorado City penetrated the steeply dipping 

beds of the foothills, .but did not prove successful. Two deep wells were bored 

there by a local oil company in 1894 and 1895. Boring No. 1 was located on the 

NW. i of NE. 1 sec. 2, T. 14 S., R. 67 W. It reached a depth of 2,020 feet, where 

operations were stopped by the collapse of a string of casing. Below the first 30 

feet of surficial materials the formation penetrated was black shale, except at 

1,247 feet, where a 5-foot bed as hard as granite was reported, which yielded some 

gas. The bormg was entirely in Pierre shale. Boring No. 2 was1 located on the 

SW. I of NE. -f sec 2, T. 14 S., R. 67 W., and had a depth of 1,300 feet, entirely in 

shale below the first 60 feet. Both holes are now full of water.

Cdlhan. A boring at Calhan, doubtless entirely in the Laramie formation, was 

sunk to a depth of 566 feet, and obtained a small amount of water at 90 feet. Coalbearing beds were reported at 250 feet and lower, but the beds were thin and the 

coal was of poor quality. The following record was reported by the Chicago, Rock 

Island and Pacific Railroad Company:
SOTJKOE OF ARTESIAN WATER. 73

" Record of boring at Calhan, Golo.

Feet.

Sand.......-...----...-.-..---...---------..-.--.----....-.----.--..-.--.-----------.- 0-23

Sandstone.---..-------.-........-........-...-.--.--.-----.-.-..........-.-------------- 23 - 38

Dark sandy shale.__._....._.__.____....._..__.............................---------.--- 38 - 63

Clay and sandy shale grading into soft sandstone.....------..--..............-....--..-----. 63 -142

"Soapstone;" thin coal layer at 232 feet-.................................................. 142 -255

Shale-......--..--------------------------------....-.------.-.....-----.-------------- 255 -306

Sandy limestone......................................................................... 306 -314

Sandy shale with coaly layers............................................................. 314 -323

"False coal"........................................................................... 323 -324

Fire clay......................................:...........................:............ 324 -3254

Dark shale............................................................................. 325J-329

Sandy shale. ........................................................................... 329 -3364

"False coal"..........................................................'................. 3364-337

Micaceous sandy shale; J-inch coal layer at 360feet......'... --------.---.----...-.--.---..... 337 -361

''Soapstone"....................-.....-----------------.....--.-.-.......-...-..----... 361 -416

Micaceous sandy shale.................................................................... 416 -432

"False coal and poor coal"............-....------.-..........-..-.-----------.-.......... 432 -435

Shale...........-.-----.......--.-.-----....---------...--..--------------..-.......... 435.-480J

Sandy false coal............................--......--.------------,------------.------.... 480i-484J

Poor coal. .............................................................................. 4844-487

Micaceous sandy layer with some shale. ----..----.-----.-._..........----.----..-.... ...____ 487 546

Sandy false coal......................................................................... 546 -551

Shale.................................................................................. 551 -5564

Shale and sandy shale._..._._.._._......----.-.....---.------------------.---......_..._ 556J-566

Franceville Junction. At this place, which is on the slope southeast of Colorado Springs, a 1,250-foot boring is reported, which was entirely in Pierre shale and 

yielded neither water, oil, nor gas.

Monument. A 765-foot boring is reported at Monument. It began in or 

above the Laramie beds and probably penetrated Pierre shale, but without result.

Florence. In the oil fields about this place there are many deep borings, mostly 

in the Pierre shale, which rarely find much water. One with a depth of 3,021 feet 

was entirely in shale, except 10 feet of dark hard rock at 2,680 feet. It encountered 

no water. f

SOURCE OF THE "DAKOTA" WATER.

The artesian waters of the "Dakota" sandstone enter this formation in the 

outcrop zone along the foot of the Rocky Mountains and also in the wide area of 

exposures in the southeast corner of the State. The exposed surface of the sandstone directly absorbs a portion of the rainfall and some of the water of streams 

crossing the outcrop also sinks into the porous beds. In the southeast corner of 

the State the formation is extensively overlain by deposits of gravel and sand, and 

much of the water which falls on this surface passes underground and in part enters 

the "Dakota" sandstone. Some of the water absorbed on the higher ridges escapes 

again at lower levels along the canyons and draws, either in springs or as small 

seeps. These are occasionally observed along the hillsides, and doubtless there 

are many others covered by talus and wash.

The area of "Dakota" sandstone exposed in the "hogbacks" along the foot 

of the mountains is relatively small; the outcropping beds usually dip steeply,
74 ARKANSAS VALLEY IN EASTERN COLORADO.

and much of the rock is so hard that water falling upon its surface runs off into 

the adjoining shale valleys, so that probably only a limited amount passes underground in this zone. Probably most of the water is absorbed in the wide outcrop 

area extending from Huerfano River to Apishapa River, northwest of Thatcher, 

and especially in the wide plateaus south and southeast of La Junta. In the latter 

area the sandstone constitutes the surface for many square miles; much of the 

land is level or gently sloping and the sandstone is soft, so that it is capable of 

absorbing a large volume of water. On the other hand,' this region is traversed 

by numerous deep canyons cut entirely through the "Dakota" sandstone, so that 

part of the underground drainage of the formation is intercepted. Purgatory 

River and Smith and Muddy creeks probably intercept all of the underground 

drainage of the sandstone in the region north and northwest of the Mesa de Maya.

DEPTHS TO "DAKOTA" SANDSTONE.

Owing to the irregular dips of the rocks in southeastern Colorado, the depth 

to the water-bearing "Dakota" sandstone varies considerably in different portions 

of the district. From a study of the distribution of the overlying formations and 

a knowledge of their thickness, obtained by measurements on the surface and in 

wells, the position of the top of the "Dakota" sandstone has been ascertained as 

shown on the map, PI. XXV. This map also shows the area in which the "Dakota" 

sandstone is at or near the surface and the region in which there is no "Dakota" 

sandstone. It will be seen from this illustration that, along the greater part of 

the Arkansas Valley, the. water-bearing horizon lies at a moderate distance below 

the surface and over wide areas it is within the reach of wells 300 to 1,500 feet 

deep. In a wide district extending from northeast of Pueblo to northwest of 

Ordway the strata dip steeply into a deep basin, so that in. northeastern Pueblo 

County, northwestern Otero County, central and eastern El Paso County, and 

Lincoln County the "Dakota" sandstone lies too deep for well drilling, and, moreover, the land in this region is too high for the water to flow. The beds also lie in 

a deep basin in central and southern Huerfano and Las Animas counties, as well 

as in the area about Florence. From Portland to Pueblo, in the vicinity of Arkansas 

River, the "Dakota" sandstone is less than 1,200 feet below the surface, and in a 

small anticline 6 miles west of Pueblo the top .of the formation is exposed in the 

river bed. East of this exposure the dips increase gradually, so that the depths 

are about 1,200 feet at Pueblo, 1,900 feet at Nyburg, and about 2,000 feet at Boone, 

which is near the center of the basin. East of Boone the amounts diminish gradually, being 1,800 feet at Nepesta, 1,270 feet at Fowler, 1,033 feet at Manzanola, 

690 feet at Rocky Ford, and 340 feet at La Junta. There is still further decrease 

to Las Animas, a short distance east of which the "Dakota"- sandstone reaches 

the surface, outcropping along the bottom of the valley nearly to the mouth of 

Big Sandy Creek. East of this point the dip carries the beds down again and the 

depths gradually increase to 405 feet at Granada, which is in the center of a shallow 

basin. On the east slope of this basin there is a gradual rise to a depth of 200 feet 

at Coolidge. Many of these features are shown on Pis. XXIII, XXV, and XXVI.
AEEA OF ARTESIAN FLOW. 75

The figures above given are to the surface of the "Dakota" sandstone, and, 

while in many districts a flow of water is obtainable from the top bed of this formation, the principal supply is usually looked for in lower beds, 100 to 160 feet deeper. 

In Kiowa County a prominent anticline extends northward from the Arkansas 

Valley, raising the beds in a low arch which extends northward to Kit Carson 

County. Owing to this uplift the "Dakota" sandstone lies at moderate depths 

as far north as the Union Pacific Railroad, especially in the lowlands of Big Sandy 

and Big Spring creeks. Unfortunately, however, all of this region is too high for 

artesian flows. Along the Rocky Mountain front the "Dakota" sandstone varies 

greatly in attitude, and in the vicinity of Colorado Springs and for several miles 

north and south the dips are steep and the sandstones are carried rapidly beneath 

the surface, soon reaching a depth of 3,000 feet. In the region northwest of Pueblo 

where the dips are gentler, the depths are much more moderate and the sandstone 

may be reached by wells 200 to 1,000 feet deep over an area of considerable extent. 

Along the base of the Wet Mountain Range the "Dakota" sandstone is extensively 

exposed, except to the south near Huerfano. River, where it dips steeply under the 

great basin in which the Spanish Peaks are situated. On the east side of this 

basin there is a zone passing through Huerfano, Cuchara, Hoehne, Elmoro, Barela, 

Trinchera, and Watervale, in which there is a gradual increase of depth from east 

to west of 600 to 1,500 feet in greater part.

AEEA OF FLOW.

Apparently the "Dakota" sandstone contains water throughout its extent, 

especially where it passes underground below the younger formations. As explained 

above, the sandstone receives much of the water at moderately high elevation, so 

that this water possesses considerable head in its passage underground. This 

head is sufficient to afford flows in nearly all of the lower lands near Arkansas 

River and along some of the confluent valleys, especially to the west. The areas 

in which flows may be expected are shown by the overprinted pattern on the map, 

PI. XXV. This representation is based on the observed pressures in wells, together 

with deductions as to gradient slopes drawn between many points along the outcrops of the water-bearing beds. These lines of the grade of the water head have 

been found to slope from the outcrops at high levels, where the water passes underground, to the outcrops at lower levels where there is leakage from springs. The 

principal area of low-level leakage in the district is along Arkansas River, between 

Las Animas and the mouth of Big Sandy Creek, where the "Dakota" sandstone 

is free to lose much of its water, consequently the head of the water becomes zero 

along this outcrop zone. The hydrostatic gradient rises to the southwest, but not 

rapidly, owing to the low declivity of the Purgatory Valley, which cuts into and 

through the sandstone for many miles. West of longitude 104° the rate of increase 

is very much higher, although it is locally diminished by the deep valleys of Apishapa 

and Huerfano rivers. Although the sandstones lie high on the mountain slopes 

in the western portion of Pueblo and the eastern portion of Fremont counties, 

there is a rapid diminution of head toward Pueblo, possibly due in part to the rise 

of the formation to the surface along the river 6 miles west of Pueblo.
76 ARKANSAS VALLEY IN EASTERN COLORADO.

The flowing wells south of Portland, at Pueblo, Fowler, Manzanola, Rocky 

Ford, Holbrook, La Junta, and Amity are along the main zone of flow. At La Junta 

there wasioriginally a flow of considerable pressure, and also at Lamar, but pumping 

has reduced the water level considerably below the present surface of the land. 

Flows at Timpas and Thatcher show an extension of the flow area to the southwest 

up the Timpas Valley, and similar lateral extension may be expected in the Apishapa, 

Huerfano, St. Charles, and other large valleys leading into Arkansas River. At 

Ordway and Sugar City the water-bearing beds appear to have been reached, but 

the land was too high for a flow and this probably was also the case at Sheridan 

Lake and Kit Carson in the wells sunk and abandoned long ago. The Government 

well northeast of Fort Lyon evidently was near the northern margin of the flow 

area, as its pressure was very slight, and two wells to the north and northwest 

have water levels considerably below the surface. The well 10 miles due south of 

Portland indicates a wide extension of the flow area in the southeast corner of 

Fremont County and adjacent portions of Pueblo County. A small flowing well 

on Plum Creek 20 miles south of Granada indicates that flows may be expected in 

the lower valleys in the central-eastern portion of Prowers County, probably as 

far south as South Butte Creek. The water level 100 feet below the surface at 

Trinidad and 80 feet below the surface at Barela indicates that the area of flow does 

not extend as far up Purgatory River and its branch valley as originally supposed.

PRESSURE OR HEAD OF THE WATERS.

As explained above, the waters in the "Dakota" sandstone under the greater 

part of southeastern Colorado possess considerable pressure, which ordinarily is 

sufficient to bring the water to the surface and in portions of the district to carry 

it to a greater or less distance above. In Pueblo the wells have a pressure of 50 

pounds to the square inch, and at Manzanola it is reported that the original pressure was 55 pounds. At Rocky Ford and Holbrook the water was found to have 

sufficient pressure to rise 80 feet, or more, in the pipe. At La Junta the well south 

of the town is about 150 feet higher than the depot, and when the well was first 

sunk the water had sufficient force to rise considerably above the surface. A heavy 

draft on the water supply at La Junta has since lowered the water level so greatly 

that even the wells on the lower land do not flow. In PI. XXVIII the head of the 

waters is shown, and in the following table are given data from various flowing and 

nonflowing wells, throwing light on the head of waters in the "Dakota" sandstone. 

Unfortunately, it was impracticable to obtain the pressures, or facts relating to the 

water level, in some of the wells, and even the figures given in most cases are only 

approximate.
U.S.GEOLOGICAL SURVEY PROFESSIONAL PAPER NO. 52 PL.XXVIII

lyM^.-J fa-^-^_l ^S-JJess Jga=i3f' £pcotti 4£^g^~T.;

)\ i i\X~>^- N M'V '

MAP OF PART OF THE ARKANSAS VALLEY, SHOWING HEAD OF WATER IN "DAKOTA" SANDSTONE 

Figures inblue indicate aMtadE of Head at wells BYN.H.DARTON

Scale 7000 Artesian head (contour lines

showing apprcrximate altitude to 

whiclithje artesian, waters majrise.

20 ID O

Area untleriain T?y

Intervals-raiyfromlOO to 5OO feet; BlackcontoursliavelOOO-footintervsasjtrotenlines hypoaietical "Dakota"sanastone

OutcTop area of 

T) alto ta" s an ds ton e
QUANTITY OF WATER. 77

List ofweUs in eastern Colorado affording data as to head of waters.

Locality.

FLOWING WELLS.

Florence (6 miles north) ...................................

Pueblo (South) .........................................................................

Grand Hotel ................................... ......... . . ....

NONFLOWING WELLS (WATEK BELOW SUKB'ACE).

Amity..............-.-.:-................................-..............................

Delhi.....................................................................................

Height to 

whica water will 

rise.

Feet. 

100±

+ 80

138

138

115

* 80

?126J

+ 150

+ 80

+ 27

+ 50

10

46

- 80

-300

- 15+

0

- 25

- 19

-100

- 50

195

-300

-100

- 50

-200

-900

Altitude of 

the land.

Feet. 

5,550

5,400

4,750

4,670

4,690

4,177

4,251

4,061

4,260

4,691

3,955

3,900

4,300

4,180

3,765

3,592

3,445

3,450

3,550

5 980

5,723

' 6,000

6,128

Head of 

water 

above sea 

level.

fen. 

5,650±

+ 5,480

4,888

4,810

4,805

+ 4,257

?4,377

4,340

3,965

4,'220

3,750±

3,592

3,431

3,450

 5,007

5,785

5,423

5,900

4,015

5,928

5,580

The lines in PI. XXVIII are constructed from the altitudes of "Dakota" sandstone outcrops and the water levels given in the above table. It is assumed that the 

gradients of head are uniform from point to point, as shown in the diagram, fig. 2, 

and this is found to be verified at numerous points in the Arkansas Valley.

QUANTITY OF "DAKOTA" WATERS.

The volume of water available from the "Dakota" sandstone in eastern Colorado is variable, and in portions of the region it has been found inadequate. The 

three principal factors in this connection are the original volume of supply, the head 

of the water, and the porosity of the sandstone. No matter how much water is 

available along the intake zone, nor the head that may be developed in its passage 

to lower levels, there can be but little volume of water available if the sandstone 

is not porous. In its surface outcrops, as well as in the borings, the rock is found 

to vary considerably in porosity, but in general it usually appears to be capable 

of holding a moderately large volume of water. The amount of water that passes 

underground seems to be large, judging from the wide area of the formation exposed 

and its surface porosity, but much of the water taken in at high altitudes is free to
78 ARKANSAS VALLEY IN EASTERK COLORADO.

escape at lower ones, so that from this cause there is not only loss of water but 

diminution of head. Where the rock is saturated with water and the head is high, 

a well tapping the sandstone will yield a larger flow than one in an area where the 

pressure is low. As heretofore explained, nearly all the pressures in the Arkansas 

Valley are low, so that there is relatively little power to force the water into the 

sandstone interstices in the vicinity of the well, so as to sustain a vigorous flow. In 

most of the wells in the Arkansas Valley only a moderate volume of water was found, 

and, when the wells are subjected to pumping, the water surface is quickly lowered 

in most cases.

The wells at Rocky Ford exhibit a larger volume of water than any others in the 

Arkansas Valley below Pueblo. Of the several that have been bored, the larger 

ones have sustained a flow of 100 to 115 gallons a, minute. The well at Manzanola, 

only 10 miles west, yields less than 40 gallons a minute, and the well at Fowler only 

half a gallon a minute. This rapid diminution to the west apparently is due to 

diminished porosity of the sandstone. There is similar but less marked diminution 

to the east, as illustrated at La Junta. At this place there are several wells which 

originally flowed 12 to 35 gallons a minute, but vigorous pumping has lowered the 

head greatly and materially diminished the volume. North and northwest of La 

Junta the volume increases, a flow of 100 gallons a minute being reported at Hoibrook. About Las Animas the wells have flows of 10 to 20 gallons. At Caddoa, 

Lamar, Granada, and Amity, where the waters are pumped, supplies of 40 to 80 

gallons a minute are obtained. In the various wells along the Santa Fe Railroad 

southwest of La Junta the amount of water flowing or available for pumping varies 

greatly. At Delhi 37 gallons and at Tyrone 50 gallons are obtained. At Timpas 

and Thatcher the volume was very small, but at Ayer the poor water obtained 

had a flow of 25 gallons. In the vicinity of Pueblo the volume also is variable. 

The first well in South Pueblo flows 100 gallons a minute, of mineral water, while 

other wells in the vicinity flow 13 to 25 gallons.

The well having the largest flow in the Arkansas Valley is the one 10 miles south 

of Portland, where, from a depth of about 1,100 feet, about 600 gallons a minute 

flow from a 6-inch casing. It is possible that the large amount of water in this 

locality is due to the proximity to the intake zone along the mountain front a short 

distance south and west. It gives promise that in the extensive prairies lying 

east and north, similar large flows may be obtained, which could be used extensively 

for irrigation.

In the eastern portion of Huerfano and the western portion of Las Animas counties there appears to be but a limited supply of water in the "Dakota" sandstone, 

except about Trinidad and southeastward, where some of the wells obtain fair supplies by pumping. Deep borings at Rouse Junction and Salt Creek, on the Denver and 

Rio Grande Railroad, found only a very small amount of water in the "Dakota" 

sandstone, and at the latter place it was too much mineralized for use. Probably 

the small volume of water in this district is due to the escape of the underground supplies in the outcrops of "Dakota" sandstone at lower levels to the east. Possibly 

-also the flow of underground currents is greatly impeded by the numerous igneous 

masses which traverse the strata in many directions.
ANALYSES OF WATERS. 79

QUALITY OF THE "DAKOTA" WATERS.

All waters which flow over or through rocks and soil dissolve various chemical compounds, the nature and amount of which have great local variation. Water 

passing through pure sand or sandstone can be contaminated only to a very slight 

degree, but nearly all rocks contain soluble minerals, especially shales, limestones, 

and red beds, which often yield a large amount of salts to waters which come in 

contact with them. Red beds generally contain gypsum and salts of various kinds 

and yield highly mineralized waters. The deep waters of the Arkansas Valley 

vary greatly in quality, but nearly all contain a noticeable amount of mineral matter. Only a few analyses are available, and these are given in the following tables. 

The chemicals are reported in their theoretic combinations, and it should be pointed 

out in this connection that there is considerable difference of opinion among chemists as to the probable compounds indicated by analyses. Most of the waters from 

the "Dakota" sandstone in the Arkansas Valley region contain 50 to 100 grains 

per gallon of minerals. Sulphate of soda, or Glauber's salts, is the most prominent 

constituent, usually with smaller amounts of sodium chloride, or common salt, and 

sodium carbonate. Small amounts of carbonates of lime and magnesia appear in 

all the analyses reported, and usually there is also some sulphate of lime or gypsum.

In some districts the quality is satisfactory; in others the waters are much 

mineralized. In the vicinity of Pueblo the principal flow contains so large an 

amount of saline ingredients that it is regarded as a valuable medicinal agent and 

is extensively bottled as such. At Grand Hotel the flow at 1,050 feet near the top 

of the "Dakota" sandstone is reported to be of excellent quality. At Fowler, Manzanola, Rocky Ford, La Junta, Las Animas, Caddoa, Lamar, and Granada the 

quality is very satisfactory. At Ayer and Thatcher the water contains too much 

mineral for use in locomotives, while at Trinidad and Barela it is satisfactory for this 

use. In the well 10 miles south of Portland the water contains considerable iron, 

but appears to be satisfactory for drinking and irrigation. At Salt Creek and Rouse 

Junction waters of decidedly saline character were reported. At St. Mary the 

water is too alkaline for use.
Analyses of waters from "Dakota" sandstone in southeastern Colorado. 

[Parts per million.1

Locality.

Do................

Do................

Caddoa. ..............'.

Do................

Do................

Do...."...........'.

Do................

Do................

Do................

Do."...............

Ayer.. .................

Do................

Do................

Do................

Do................

(C.C.& I. Co.) ........

Depth.

Feet. 

580

226

500

300

60

340

439

420

420

425

580

620

252

311

340

240

358

322

580

1,400

1,260

1,219

1,545

Sodium.

Na. 

160

368

543

355

32

380

360

415

524

259

255

260

638

702

182

135

89

109

107

213

242

202

Potassium.

If.

6 4

7.0

16

79

Calcium.

Co.

48

96

42

74

16

5.5

15

84

90

118

31

35

98

97

91

76

166

140

60

103

177

542

Magnesium.

Me.

6.0

27

39

27

10

114

7.4

4.4

18

39

72

42

30

41

 46

40

50

31

30

232

159

Sulphuric 

acid.

SO,. 

133

692

853

717

89

922

440

676

578

520

695

454

1,180

775

905

1,190

756

933

575

487

411

418

666

'317

526

683

1,175

3,235

Chlorine.

Cl.

28

33

33

19

31

18

54

58

33

28

70

31

21

133

104

25

21

16

18

125

25

34

186

2,615

Carbonic 

acid.

ros.

186

114

369

114

63

462

244

170

171

140

286

96

247

91

108

295

295

76

101

96

80

85

260

139

169

270

258

Silica.

SiOi.

49

50

16

20

17

12

12

15

16

13

16

9.4

6

Iron oxide+ aluminum 

oxide.

FezOs+ 

AliOs.

1.71

7.3

4.0

125

16

20

71

Organic 

and 

volatile.

40

267

40

 96

39

37

(°)

104

215

48

70

113

80

96

119

62

Other 

constituents.

0.17

6.0

2.2

108

20

Total 

solids.

602

1,338

318

2,375

1,362

1,108

1,627

888

2,390

2,189

1 901

1,098

963

845

873

1 148

1,061

1,334

2,499

9,350

Year.

1899

1899

1895

1898

1898

1895

1898

1899

1899

1899

W. 

R

 a Present.
These constituents may be hypothetically combined as follows:

Analyses of waters from "Dakota" sandstone in southeastern Colorado. 

[Expressed in hypothetical combinations and in grams per gallon.]

Locality

Do................

Do................

Do................

Do................

Do................

Do................

Do................

Do................

Do................

Delhi..................

(C. C. & I. Co).....

Depth.

Feet. 

580

226

600

300

50

280

439

420

420

425

700?

554

580

620

755

252

267

311

340

358

322

580

1,230

1,400

1,260

1,219

1,545

Sodium 

sulphate.

11 50

EQ 07

60.08

3.45

75 21

3&09

58.33

50 03

45.00

60.16

39.14

102.08

42.44

4420

53.41

65.40

80.80

OO Art

22.00

14.03

17.67

17.72

23.68

41 92

41.43

22.92

113.30

Sodium 

chloride.

2 72

3.20

5.17

3.21

1.88

0 (\A

1.78

4.66

5. 60

2.30

3.18

1.87

6.73

2 98

2.31

12.80

10.00

2 40

2.00

1.63

1.35

12.07

13.61

1.82

11.02

252.40

Sodium 

carbonate.

10.48

.19

13.33

.64

12.50

22.84

3.90

25.60

25.20

15.95

25.16

Potassium 

chloride.

0.70

.76

1.82

8.81

Calcium 

sulphate.

2.11

4.39

17.85

23.52

33.72

19.00

18.13

15.15

32.92

3. 43

10.94

107.00

Calcium

carbonate.

7.08

4 52

13.98

6.07

3.69

17 53

10.73

2

QA

.80

2.12

2.16

12.24

13.79

4.60

5.10

17.84

6.28

2.64

25.90

Magnesium carbonate.

1.22

C ,JQ

7 0*1

4.26

2.09

23. 17

1.47

4.20

1 50

.90

3.57

2.51

7.96

7.48

8.89

6.00

7.87

6.59

6.97

6.37

18.97

6.16

11.65

.35

Magnesium 

sulphate.

1.69

5.06

8.11

12.13

2.27

4.69

66.67

45.99

Silica.

2 89

1.02

2.92

.93

1.20

1.00

.72

.70

.99

.93

.75

.91

.55

.35

Iron and 

alumina.

0.10

.43

.35

 .91

1.17

Organic 

and 

volatile 

matters.

2.33

4.20

3.45

15.63

5.60

2.16

7.29

. 6.10

8.16

12.59

4.10

6.60

4.70

5.60

Q 99

6.53

3.65

20.30

Other 

constituents.

^

0.01

.35

1.20

*

Total.

35.33

78.21

119. 49

78.23

18.60

138.97

6ft 90

80.30

64.80

95.18

 » 51. 74

139. 82

8284

95.18

127.95

111.20

125.20

56.30

49.48

51.11

70.18

07.20

106.90

62.03

7&02

6146 11

546.00

Year.

1899

1897

1899

1899

1899

1895

1898

1898

1895

1898

1899

1899

1905

W. 

W. 

W. 

W. 

. 

Win

P

H. 

E

Ip

Ol

a

I

" Induding lithium chloride, 0.17; ammonium carbonate, 0.12; strontium carbonate, 0.06: and manganese carbonate, trace. & Induding lithium c
82 ABKAN9A9 VALLEY IN EA9TEBN COLORADO.

In the analysis of the water of the first well at La Junta it is reported that when 

the analysis was made the water had deposited a slight brown sediment containing 

iron, manganese, silica, and a trace of phosphoric acid, all of which, except the last, 

are included in the analysis. Free and semicombined carbonic acid (C02 ), 124.4 

parts per milion; total COa , 250.2 parts per million. A trace of lithium was found.

When the water from the first artesian well at Rocky Ford was received in 

Washington it had deposited a sediment containing silica, iron oxide, a trace (?) of 

alumina, and phosphoric oxide. Traces of bromides (?), iodides, and phosphates 

were found in the" water and some organic matter not determined. Boron, fluorine, 

and barium were absent. Free and semicombined carbonic acid (CO2 ), 106.57 parts 

per million; total CO2 , 176.90 parts per million.

WATERS OF THE "RED BEDS" AND THE MORRISON FORMATION.

Under the greater part of southeastern Colorado the top of the "Red Beds" lies 

100 to 300 feet below the base of the "Dakota" sandstone. In the r.egion north of 

Arkansas River and east of Fountain Creek, these "Red Beds" are too deep 

to be reached by ordinary well drilling, but along the river valley and southward they are at moderate depths. The deep borings at La Junta, Manzanola, 

Thatcher, Rouse Junction, Salt Creek, Caddoa, Fort Lyon, and Bloom penetrated 

more or less deeply into the "Red Beds," but obtained no satisfactory water supplies. 

At a few points in Kansas the "Red Beds" have been found to contain good 

water, but in most cases it is too highly mineralized to be of any use. Probably 

water-bearing strata will be found in the "Red Beds" in Colorado, but it is doubtful 

if any of them will yield useful supplies, and ordinarily a boring should be discontinued 

as soon as it enters the "Red Beds." The Mowison formation includes thin beds of 

sandstone which often contain water, but the amount so far found is too small to be of 

value. At Manzanola the "Red Beds" were penetrated from 1,653 to 2,110 feet and 

several water-bearing strata were found, but it is reported that the water was very 

impure. In the Bloom boring, the "Red Beds" extend from 455 to 1,162 feet and 

yielded some water of bad quality at 1,006 and 1,145 feet, of which analyses are given 

in the table below. At Rouse Junction the water found in the "Red Beds" at a 

depth of 1,760 feet was reported as "fresh," but it1 rose only about 200 feet. The 

following are analyses, made by W. A. Powers, for the Atchison, Topeka and Santa 

Fe Railway Company, of waters from the "Red Beds" at Bloom and from the 

Morrison formation at La Junta and Caddoa, at the depths stated:
ANALYSES OF WATERS.

Analyses of waters from "Red Beds " and Morrison formation in easternColorado.

[Parts per million.]

83

Constituent.

SUioa, SiO2 . ........................................

Bloom.

1,006 Jeet.

2,131

146 

88 

1,844 

221 

1,871

255

6,556

1,145 Jeet.

846

229 

65 

1,342 

254 

553

138

3,427

La Junta.

663 Jeet.

323

23 

24 

572 

24 

136 

56

66

1,224

757 Jeot.

270

12 

6.4 

424 

11 

109 

17

58

907.4

Caddoa.

440 Jeet.

586

143 

75 

1,282 

39 

329

199

2,653

560 feet.

753

38 

23 

702

82 

587

136

. 2,321

Analyses of waters from " Bed Beds " and Morrison formation in eastern Colorado. 

 {Expressed in hypothetical combinations and in grains per gallon.]

Constituent.

Bloom.

1,006 feet.

159.63 

21.29 

148. 36

21.30

17.85

14.93

383.30

1,145 Jeet.

116. 13 

24.56 

4.92

33.61

13.20

8.08

200.50

La Junta.

663 feet.

49.54 

. 2.31. 

4.40

3.32

4.90 

3.26

3.85

71.58

757 feet.

36.70 

1.40 

7.70

1.80

1.30 

1.00

3,40

53-30

Caddoa.

440 feet.

101. 18 

3.73

9.38 

13.94

15.31

11.66

155.20

560 feet.

60.79 

7.96

48.72

5.62

4.77

7.93

135. 79

WATERS OF LARAMIE AND ASSOCIATED FORMATIONS.

The Fox Hills (Trinidad), Laramie, and overlying formations all contain water, 

but unfortunately these formations are so distributed that their water supplies are 

not likely to be very useful. The area extending from the Raton Mesa to the Spanish 

Peaks and beyond is a rough upland of high ridges and steep-sided valleys, and, 

moreover, the conditions are not favorable for flowing wells, except possibly in. some 

of the deeper valleys. In the large synclinal area east of Colorado Springs well water 

is obtainable at various depths in the Laramie and associated beds, a few ranches 

drawing their supplies from this source. A deep well at Calhan, described on page 72, 

failed to obtain satisfactory water supplies in the Laramie formation, and there was a 

similar experience with a well at Monument. »

In the Florence basin the Laramie formation lies at moderate depths and 

doubtless will prove to be water bearing. Some of the wells west of Florence 

obtained a moderate amount of water from this source, and in some of the coal mines 

there is sufficient water to be an obstacle to mining operations.
84 ARKANSAS VALLEY IN EASTERN COLORADO.

WATERS OF THE LATER TERTIARY DEPOSITS.

In the wide areas covered by later Tertiary deposits abundant water supplies are 

usually obtainable for pump wells. The deposits consist of various materials which 

absorb a large proportion of the rainfall. This water sinks low in the deposits, and 

usually the largest amounts are found in the basal portions lying on the Pierre and 

Niobrara shales. Where the contact of the shales and overlying sands is exposed 

there are usually springs, by which a portion of the water escapes to the surface.

Wells in the later Tertiary deposits vary in depth from 10 to 250 feet, the deepest 

ones being in the eastern portion of Cheyenne County. At Cheyenne Wells a large 

supply of excellent water is obtained at the base of the later Tertiary deposits at a 

depth of 257 feet. Ordinarily a large supply is found in these lower gravels, but it is 

well known among drillers that after the shale is reached it is useless to sink deeper.

WATERS IN THE DUNE SANDS.

Owing to their porous nature the dune sands absorb a large percentage of the 

water that falls upon them, an'd they usually lie in such manner as to intercept more 

or less of the surface run-off from the adjoining slopes. Accordingly they accumulate 

considerable water and afford excellent supplies for shallow wells throughqut their 

area.
INDEX.

Page. 

Acanthopecten carbonif eras, occurrence of............ 18

Agriculture, Department ol, wells of, records of... 58-69,68 

Allorisma subeuneatum, occurrence of................ 19

Alluvium, occurrence and character of j.............. 35

Altitudes, data on ................................._. 8

American Beet Sugar Company, well of, record of-.... 53

Amity, wells at and near, heads in.................... 77

wells at and near, record of....................... 65-66

water of, analysis of...........................

yieldof.................................... 78

Analyses of water from Dakota formation............. 80-81

Anchura (Drepanocbilus) americana, occurrence of .. 31 

Anticlines, occurreneeof.............................. 9

Apishapa formation, character and occurrence of .. 13,29-30

fossilsof............................................. 30

Apishapa River, canyon of, view of.................... 10

character of........................................ 8

Arapahoe formation, correlation of.................... 38

See also Poison Canyon formation. 

Archer, William, aid of ............................... 8

Arikaree formation, deposition of..................... 49

occurrence of...................................... 12

Arkansas River, altitudes on.......................... '8

character of....................................... 8

drainage basin of, map of......................... 8

valley of, geologic map oJ...................... Pocket.

view on............................................ 30

~Arimgfoii;T^6llneaf7'ireard in'.r.r.-.::'.-:.-:,,.,.......... 77

well near, record of ............................... 63

Artesian conditions, map showing.................. Pocket.

Artesian flows, area of ................................ 7»75

area of, map showing........................... Pocket.

availability of..................................... 7

Astartella concentrica, occurrence of................. 18,20

Athyris subtilita, occurrence of ....................... 15

Atlantosaurus fauna, occurrence of ................... 21

Aviculopecten occidentalis, occurrence of............ 20

Ayer, wells at, record of............................... 56

wells at, water of, analyses of..................... 80-81

B.

Baculites compressus, occurrence of................... 30,31

ovatus, occurrence of......................... . 31

Badito.formation, character and occurrence of.... 13,18,44

Barela, well at, head in ............................... 77

well at, record of.................................. 67

Basins, occurrence of.................................. 9

See also Florence basin. 

Baxter siding, well near, record of.................... 72

Belierophon inspeeiosus, occurence of ................ 20

percarinatus, occurrence of..................... ^.. 18,20

sp., occurrence of.................................. 18,19

Page. 

Benton group, character and occurrence of.. 11,13,38,40,43

deposition of....................................... 48

section*of, figure showing......................... 51

Blackwell ranch, well at, data on..................... 59

wellat, headin.................................... 77

Bloom, well at, head in................................ 77

wellat, record of ...................I.............. 66-57

rocksin........................................ 21

water of, analyses of........................ 80-S1,83

BoggsMat, well on, data of........................... 61

Bolodont, occurreneeof.............;................. 20

Bone-bearing sandstone, description of............... 22

viewof ............................................ 22

Boone, well at, record of .............................. 71

C.

Oaddoa, wells at, head in............................... 77

wellsat, recordoJ................................. < 64

water of, analysis of........................ 80-81,83

yieldof.................................... 78

Calhan, well at, record of ..I....................... 72-73,83

Cambrian rocks, fossils in ............................. 13,14

occurrence and character of............. 10,13-14,36-37

Cambrian time, history of............................. . 45

Camerella, occurrence of.............................. 14

Campophyllum torquium, occurrence of.............. 18

Canyon, bone-bearing sandstone near, view of........ 22

Dakota sandstone near, views of.................. 12,22

Fremont limestone near, view of.................. 16

Fa.rrtlng.sandstone near, viewsof ..,..-,,...-..... 10,42

hogbacksat andnear, viewsof ................... 12

Morrison formation near, viewof ................. 38

section near........................................ 41

views near................................ 12,16,22,38,42

wells at and near, data on......................... 62

Canyon embayment, description of ................... 38-43

geologic map and cross sections of, plate showing. 40 

Carboniferous rocks, occurrence and character of..... 10,

13,15-26 

Carboniferous time, history of......................... 46-47

Carlile formation, character and occurrence of....... 13,

28,38,42-13,45 

fossils in............................................ 28

viewof............................................ 32

Cephalopods, occurreneeof........................... 31

Chandler, section near................................ 43

well at, data on.................................... 62

Cheyenne Wells, well at, record of.................... 68

wellsat, waterof.................................. 84

Chonetes granulif era, occurrence of................... 20

mesolobus, occurreneeof.......................... 18,20

Chugwater formation, character and occurrence of. 13,16,37 

deposition of.--....- -- ............ 46-47

See also Red Beds.

85
86 INDEX.

Page, 

dark's mineral springs, water of...................... 59

Colorado, eastern, geology of.......................... 9-12

rocks in.....................:...................... 10-12

structure of........................................ 9

topography of..................................... 8

Colorado City, Ked Beds at, view of................... 38

section at.......................................... 17

well at, data on.................................... 72

Colorado Coal and Iron Co., well of, data on.......... 60

well of, water of, analysis of....................... 80-81

Colorado Southern Railroad Co., well of, data on..... 67-68

Columbia Heights, Pueblo, well at, record of.......... 60

Comanche series, character and occurrence of........ 13,25

deposition of....................................... 48

fossils in .....................................i..... 25

Cooper well, record of................................. 58

Creamy sandstone. See Tensleep sandstone.

Cretaceous formations, character of................... 13

descriptions of..................................... 21-34

occurrence of...................................... 10-12

outcrops of......................................... 9,12

Cretaceous time, history of ............................ 47-48

Crosby, \V. O., on Manitou embayment................ 36

Cross, Whitman, on Dakota sandstone ................ 26

on igneous rocks................................... 35

on Ordovician rocks............................... 14

on Bed Beds....................................... 17

Cuchara, well at, dataon.............................. 70

Cuchara formation, character and occurrence of...... 13,34

deposition of....................................... 49

Culebra Range, section of ............................. 19

Cunningham, A. A., analysis by ...................... 80-81

D.

Dakota formation, artesian wells from, area of ....... 75-76

character of ......................... 7,10,13,25-27,40-44

configuration of ................................... 7

deposition of ...................................... 47-48

depth to....... ..................................... 74-75

map showing ............................... Pocket.

fossils of............................................ 26

iiogharks,of, views of ....................... -,.,.....12,-22

occurrence of...........'............. 7,11,25-27,38,40-44

outcrops of ........................................ 9,11

relations of other rocks and, map and cross sections showing .......................... 36,40,46

structure of, map showing ........................ 56

sections of, figures showing..................... 14,40,51

strata above, section of, figure showing........... 51

water holein, view of............................. 44

water of, analyses of............................... 80-81

depth to, map showing ..................... Pocket.

derivation of .................................. 7

head of ..................................... 50,76-77

map showing.............................. 76

leakage of........-..-..............-...."...... 50,52

' occurrence of.... .............................. 50-82

quality of....................................... 79-82

quantity of .................................... 77-78

source of....................................... 73-74

wells to............................................ 52,68

Dalinanella tcstudinaria, occurrence of............... 15

Dearborn Drug Co., analysis by ....................... 80,81

Delhi, well at, head in ................................ 77

well at, record of .................................. 66

water of, analysis of........................... 80-81

Denver, basin at....................................... 9

Page. 

Denver and Rio Grande Railroad, analysis by ........ 80-81

Denver formation, correlation of...................... 34

See also Cuehara formation: . 

Derbya crassa, occurrence of.'.....................:... 19,20

Devonian rocks, occurrence of ........................ ' 10

Devonian time, history of ............................. 46

Didymoceras cochleatum, occurrence of .............. 31

nebrascense, occurrence of ........................ 31

Dinosaur, occurrence of ..................'............. 33

Drainage, description of............................... 8

map showing ...................................... 8

Drepanochilus americana, occurrence of.............. 31

Dune sands, occurrence of............................. 35

water in ........................................... 84

E. ' 

Eldridge, G. H., on Morri, on formation.

Blmore, well at, data on............................... 70

Embaymente, location of .............................. 9

See also Canyon embayment, Manitou embayment. 

Emmons, S. F., on Cambrian history. . ................ 45

Endlich, F. M., on Culebra Range..... ................ 18

Kuphemus carbonarius, occurrence of ................. 18

Bxiteloceras chcyennense, occurrence of .............. 31

F.

Fariss House, Pueblo, well of, data on ................. 60

well of, head in.................................... 77

water of, analysis of ........................... 80-81

Field work, extent of........................... ....... 8

Fisher, C. A., fossils found by ......................... 34

work of.....----......--.-.-..-------......-....--. 8

Flexures, description of ................................ 9

Florence, basin at..................................... 9

basin at, wells in .................................. 83

wells at and near, data on. ........................ 73

head in........................................ 77

records of ...................................... 61

water of, analysis of ........................... 81

Formations, descriptions Gt..,,-.., ..,.-- ,».. . r..-.-, .-.,.^. .-.-.- 16=85" 

" -stfatigraphlc table of............ .................. 13

Fort Lyon, well at, head in...... ...................... 77

^well at, record of .................................. 58-59

Fountain formation, character of ............ 13, 17-18, 37, 39

description of ....................................... 10

occurrence of............................. 17-18,37,39-44

vertical beds of, view of ........................... 18

See also Red Beds. 

Fowler, well at, record of ..........'................... 54

Fox Hills formation, character and occurrence of .... 12, 32

deposition of ...................................... 48

fossiljs of ........................................... 32

waterof ........................................... 83

Franceville Junction, well at, data on ................ 73

Fremont limestone, character of ................... 13, 14, 39

fossils in........................................... 14,39

occurrence of ................................... 14, 39-43

view of ...........................................". 16

Fucoid halymenites, occurrence of .................... 32

Fuson formation, correlation of ...............'........ 11

Garden of Gods, Ked Beds in, view of ................. 18

section near ....................................... 17

Garden Park area, rocks in. .................. ...... 39-40

Gauger, J. E., well of, record of ....................... 55-56
INDEX. 87

Page. 

Geologic history, narrative of ......................... 45-50

Geologic sections, figures showing .................... 14,36

Geology of Arkansas Valley region, description of.... 12-50

of eastern Colorado, description of................ 10-12

Gilbert, G. K., fossils collected by..................... 31

on Dakota sandstone.............................. 26

on igneous rocks................................... 36

on Morrison formation............................. 23

on Nussbaum formation ........................... 34

on Red Beds................................. 17-18,21,23

work of............................................ 7

Glauconitc, occurrence of............................. 36

Glen Eyrie, Colo., sections near....... .>.......-.....-. 15,17

Grabau, A. W., fossils found by....-.......--.......--. 15,37

Granada, wells at, head in............................ 77

wells at, record of................................. 65

water of, analysfsof........................... 80-81

yield of.................................... 78

Grand Hotel, Pueblo, well of, data on ................ 60

well of, head in.................................... 77

water of, analysis of........................... 80-81

quality of.................................. 79

Graneros shale, character and occurrence of.. 13,27,38,42,45 

Grape Creek, Morrison formation on, view of ......... 39

Great Plains, view on.................................. 8

Greenhorn limestone, character of.................. 13,27-28

fossils in........................................... 28,42

views of........................................ 28

occurrence of................................ 28,38,42-43

view of............................................ 26

Greenhorn Mountain, rocks on........................ 43-46

rocks on, map showing............................ 40

Gryphsea corrugata, occurrence of .................... 25

Gypsum, deposition of................................. 46-47

occurrence of...................... ............. 17,79

H.

Halysites cateuulatus, occurrence of.................. 14,39

Harding sandstone, character of ................... 13,14,39

fossils in ........................................... 14

occurrence of................................... 14,39-43

quarry in, view of................................. 16

views of........ .................................... 10,42

Harding's quarry, section at........................... 41

Hatcher. J. B., on Morrison formation ................ 22

Hayden, F. V., on Manitou embaymeut. ............... 36

Haystack Butte, view of........"....................... 10

Head of artesian water, amount of .............. 50-51,76-77

map showing ...................................... 76

Heteroceras (Exiteloceras) cheyennense, occurrence

of.......................................... 31

(Didymoceras) cochleatum, occurrence of........ 31

(Didymoceras) nebrascense, occurrence of........ 31

sp., occurrence of............... .................. 31

High Plainsin Colorado, map of ...................... " 8

Hillebtand, W. F., analyses by.............'........ 31,80-81

Hills, R. C., on Badito formation...................... 18,44

on Dakota formation .............................. 26-27

on igneous rocks.............................. .... .36

on Morrison formation ............................ 23

Hochne, well at, data on.............................. 69

Hogbacks, views of.................................... 12,18

Holbrook, well at, data on ............................ 56

well at, head in ................................... 76-77

Holly, well at, data on ................................ 66

Page. 

Horse Creek, well on, record of .................__.. 59

Huerfano formation, character of..................... 13

deposition of....................................... 49

Hueffano River, character of.......-......-.__......._ 8

Hustedia mormoni, occurrence of..'.............-..... 19,20

Hydrostatic grade, definition of....................... 50,52

figure showing .................................... 52

I.

Igneous rocks, distribution of, plate showing...... Pocket.

occurrence of.................................... 9,35-36

Inoceramus, occurrence of...........-.........'....... 22,29

crispii var. barabini, occurrence of................ 31

defonnis, occurrence of ........................... 29

. . labiatus, occurrenceof ......................... 28,38,42

view of........................................ 28

sagensis, occurrence of............................ 31

vanuxemi, occurrence of.......................... 31

Iron Springs. See Bloom.

J.

Jurassic rocks, occurrence of.......................... 10-11

K.

Kansas Pacific Railway, well of, data on..........._ 69

Kit Carson, well at, data on........................... 69

La Junta, Carlile sandstone near, view of............. 32

ridge near, well on, viewof....................... 54

Timpas limestone in quarry near, view of ........ 26

wells at............................................ 76

head in ........................................ 76

records of...................................... 51-55

- rocks in........................................ 21

water of, analysis of........................... 80-83

yield of..................................... 78

Lakota formation, correlation of...................... 11

deposition of ...................................... 47-48

Lamar, wells at, data on .............................. 64,76

wells at, head in .................................. 77

record of ...................................... 64-65

water of, analysis of........................... 80-81

yield of.................................... 78

Laramie formation, character of................ 12,13,32-33

coals in............................................ 32-33

occurrenceof........................... 9,12,32,38,40,43

waterof ................^.....--......--........... 83

Las Animas, wells at and near, head in............... 77

wells at and near, records of................ 57-59,03-64

waterof, analysis of........................... 80-81

yield of.................................... 78

Leakage, effect of, on artesian wells.......... 50,52,75,77-78

effect of, figure showing........................... 52

Lee, W. T., fossils collected by.......................... 18

on Cambrian rocks ................................ 14,37

on Comanche series................................ 25

on Morrison formation ............................ 23-25

on Ordovician rocks............................... 15

* sectionsby...................................... 19,23,24

work of............................................ 8

Lenox well,dataon.................................... 55

Lida bellistriata, occurrence of........................ 18
INDEX.

ISfc

Page. 

Llngula, occurrence of............................. 26

pinnseformis, occurrence of........................ 13

Lingulepsis sp., occurrence of......................... 13

Lower Wyoming beds. .See Fountain formation.

Lucina occideritalis, occurrence of.................... 30-31

occidentals var. ventricosa, occurrence of........ 31

Lykens formation. See Upper Wyoming beds. 

Lyons sandstone. See Tcnsleep sandstone.

M.

McLane, information from............................ 68

McLane well, data on .................................. 61

McNeen well, data on .'................................ 65

McVay, C. H., aid of................................. 8,53,56

Manitou embayment, description of................... 36-38

geologic map of.................................... 36

rocks in ............................................ 36-38

sections of, plate showing ......................... 36

Manitou limestone, character of ................ 13-14,37,39

fossils in.......---......-........-..-...--.......-- 14

occurrence of............:.............--. 13-15,37,39-10

Manzanola, wells at, head in..'........................ 76-77

wells at, records of................................. 53

yield of........................................ 78

Map of artesian conditions in Arkansas Valley...... Pocket.

of central-western United States................... 7

of drainage basin of Arkansas Kiver............... 8

showing head of water in Dakota sandstone ...... 76

showing structure of Dakota sandstone............ 56

Map, geologic, of Arkansas Valley.................. Pocket.

of Canyon'embayment ........ 1................... 40

of Manitou embayment-........................... 36

of Wet Mountains ................................. 46

Marlaman well, record of ............................. 59

Mesa de Maya, location of............................. 8

rooks of............................................ 36

Millsap limestone, character and occurrence of...... IS,

15-16,20,39,43 

deposition of....................................... 46

fossils in........................................... 15

Mineral Park, well of, data on ........................ 60

well of, water of, analysis of...................... 80

Minnekahta limestone, occurrence of....-......_..... 16-17

Miocene time, history of............................... 49

Mississippian rocks, character of...................... 13

Monument, well at, data on........................... 73,83

Monument Creek formation, character and occurrence

of....................................... 12-13,34

deposition of....................................... 49

fossils of ........................................... 34

Morrison formation, bone-bearing sandstone in....... 22

bone-bearing sandstone in, view of................ 22

character and occurrence of .... 11,13,21-25,38-40,42-44

deposition of....................................... 47-48

fossils in....................................... 21-22,397

section of......................

figure showing.............

view of.-.--....--..............

water of, analysis of...........

quality of.................

Murchisonia copei, occurrence of.

Naticopsis altonensis, occurrence of................... 18

altonensis var. gigantea, occurrence of.......... 18

Nautilus dekayi, occurrence of........................ 31

Page.

Nepesta, tepee buttes near, view of.................... 32

Niobrara chalk, character and occurrence of.......... 11,38

deposition of...........................'............ 48

fossils of, views of.................................. 28

section of, figure showing.......................... 51

North Pueblo Heights, well at, data on................ 61

Nucula ventricosa, occurrence of...................... 18

Nussbaum formation, character and occurrence of. 13,84-35

deposition of....................................... 49

sand from.......................................... 35

Nyburg siding, well near, record of................... 72

o.

Obolus similis, occurrence of.......................... 36

Ogalalla-Nussbaum beds. See Nussbaum formation.

Oil Creek, rocks on .................................... 39

Oligocene rocks, deposition of......................... 49

occurrence of-.........-.-...-.-.-...--............ 12

Opileta, occurrence of................................. 14

Orbiculoidea convexa, occurrence of.................. 18

missouriensis, occurrence of....................... 18

sp., occurrence of.................................. 20

 Ordoviciun formations, character and occurrence of.. 13-15

descriptions of..................................... 14-15

occurrence of................................... 10,39-43

section of.....-.......--.-.-.---......-.......-.... 15

Ordovician time, history of............................ 46

Ordway, well at, head in.............................. 77

well at, record of.................................. 62-63

well near, record.of................................ 63

Orthoceras sp., occurrence of.......................... 18,20

Ostrea congesta, occurrence of ........................ 29-30

congesta, view of.................................. 28

glabra, view of .................................... 83

inornata, occurrence of............................ 31

Patellostium montfortianum, occurrence of. 

Peale, A. C., on Manitou embayment........

section by ...............................

Pelecypod, occurrence of.

18 

36 

IB 

18 

Pennsylvanian rocks, character of.......... ....... 13

Pennsylvanian time, history of ....................... 46

Permian time, history of............................... 46-47

Phillipsia sp., occurrence of........................... 19

Pierre shale, character and occurrence of............ 11,13,

30-31,42-43 

deposition of.................._.................. 48

fossils in........................................... 30-31

oilin .............................................. 11

 section of, figure showing......................... 51

tepee buttes in .................................... 30-31

limestone of, analysis of....................... 31

view of ........................................ 32

Plains, marl, occurrence of............................ 34

Pleurotomaria perizomata, occurrence of............. 18

sp., occurrence of.................................. 18

Pliocene rocks, deposition of.......................... 49

occurrence of....................'.................. 12

Plum Creek, well on, data on......................... 59,76

well on, head in................................... 77

canyon of, sections in ....................... 20-21,23-24

Poison Canyon formation,character and occurrence of. 13,83 

deposition of ...................................... 49

fossils of........................................... 33-34
INDEX. 89

Page. 

Portland, well near, view of.......................... 62

wells at, data on................................... 62

head in........................................ 77

yield of........................................ 78

Post-Laramie time, history of.......................... 49-60

Powers, W. A., analyses by............................ 80-83

Pressure. See Head.

Prlonocyclas wyomingensis, occurrence of............ 28

Productus cora, occurrence of......................... 18,20

costatus, occurrence of............................ 18

longispiuus, occurrence of........................ 18

nebrascensis, occurrence of.-.............--.--...- 20

Ptychoparia, occurrence of............................ 13,39

Ptychoceras crassum, occurrence of--.........------.. 31

Pueblo, wells at and near, head in..-.........----.... 76-77

wells at and near, records of ................... 59-61,72

water of, analyses of.......................... 80-81

quality of........-...................------ 79

Pugnellus, occurrence of ....-.-...........--.-..------ 28

Purgatory River, description of.................. 8

stonewall on, views of................ ........ 18,24

OQuaternary deposits, character of. .............. 12,13,35

occurrence of........................... ..... 35

Quaternary time, history of ............ ..... .. 50

K.

Raton Mesa, location of................... ......... 8

rocks of................................j........... 86

Red Beds, character and occurrence ol...... 10,16-21,40,42

correlation of...................................... 21

fossils In........................................... 18-20

deposition of ...................................... 46

divisionsof......................................... 10

conglomerate at base of, view of .................. 42

occurrence of...................................... 10

sections of...................................... 17,19-21

figure showing ................................ 51

water of, analyses of............................... 83

quality of...................................... 82

views of........................................... 18,38

Bed Rock Canyon, section in ......................... 24

Relief map of Arkansas River Valley.................. 8

Ritchie Creek; well on, data on ....................... 62

Rocky Ford, well at, view of.......................... 54

wells at, head in................................... 76-77

records of...................-...............'... 52-53

water in, analysis of........................... 80-82

quantity of................................ 78

Rotella verrucelifera, occurrence of................... 18

Bouse Junction, well at, head in...................... 77

well at, records of.................................. 69-70

water of, analysis of...................... .

yield of.................................... 78

Rusty zone, character of ..................__........ 30

St. Mary, well at, data on ...__...........__. 62

well at, water of, quality of.......... ..... 62,79

SaltCreek, well at, head in ........................_ 77

well at, record of.................................. 70-71

water of, analysis of........................... 80-81

yield of.................................... 7S

Sanitarium, well of, data on .......................... 62

Saurians, occurrence of ...................... 22,24,34,47-48

Page.

Scaphites nodosus, occurrence of...................... 31

nodosus var. quadrangularis, occurrence of....... 31

var. brevis, occurrence of..................... 31

Schizodus wheeleri, occurrence of.................... 19,20

Sections, geologic, across Colorado, figures showing .. 14

Selenite, occurrence of................................ 80

Seminula argentea, occurrence of..................... 18,20

Sheridan Lake, well at, data on ....................... 69

well at, head in.................................... 77

Siebenthal, C. E., section by .......................... 43

work of............................................ 8

Silurian rocks, absence of.............................. 10

Silurian time, history of............................... 46

Small, C. H., well of, record of........................ 60-61

Smith, W. S. T., work of............................... 8

Soda sulphate, occurrenceof.......................... 79

Soleniscus brevis, occurrence of....................... 18

sp., occurrence of.................................. 18,20

South Platte River, character of....................... 8

South Pueblo, well at, record of...................... 59-60

Spanish Peaks, basin near............................. 9

Sphserodoma texana, occurrence of ................... 18

sp., occurrence of.................................. 18

Spirifer cameratus, occurrence of...................... 18,20

centionatus, occurrence of......................... 15

rockymontana, occurrence of................ 15-16,18,43

Sqnamularia perplexa, occurrence of ................. 18,20

Stanton, T. W., fossils determined by.................. 31

fossils found by.................................... 11,26

on Comanche series ............................... 25

Stonewall, viewsof.................................... 18,24

Straparollus catilloidcs, occurrence of......-"-........ 18

Stratigraphy, description of........................... 12-35

Streams, data on....................................... 8

Structure, description of .............................. 9

map showing...................................... 56

Sugar Beet and Irrigated Land Co., well of, record of. 66

Sugar City, well at, data on ........................... 63

Syringopora sp., occurrence of ........................ 18

T.

Temnocheilus winslowi, occurrence of................ 19

Tensleep sandstone, character and occurrence of.. 10,18,87 

Tepee buttes, limestone in, analysis of................ 81

occurrence of...................................... 30,81

view of ............................................ 32

Tertiary formations, character of...................... IS

descriptions of..................................... 34-35

occurrence of.................................... 9-10,12

water of................:...............---......... 84

Tertiary grit, occurrence of............................ 34

Tertiary time, history of............................... 48-49

Thatcher, Greenhorn limestone near, view of......... 26

water hole near, view of........................... 44'

well at, data on.................................... 69

wells near, records of.............................. 66-67

Thetis circularis, occurrence of ....................... 31

Timpas, well at, head in............................_ 77

record of........................................... ' 56

waterof, analysisof........................... 80,81

Timpas limestone, character of.;................... 13,28-29

fossils of............................................ 29

occurrence of ............................. 28,38,40,42-43

viewsof...:........................................ 26,32

Titanotherium, occurrence of ......................... 34

Trachydomia wheeleri, occurrence of................. 18
INDEX.

Page. 

Triassic rocks, character and occurrence of............ 10,13

Trinidad, stone wall near, views of.....---.--...-..--. 18,24

well at, head in..............j..................... 77

record of....................................... 67

Trinidad sandstone, character of...................... 13

Troy, well at........................................... 69

Two Butte, igneous intrusion at....................... 9,36

view of ..........,........-...............--------. 44

Tyrone, well at, record of.............................. 06-67

well at, water of, analysis of...................... 80-81

U.

Unio, occurrence of.................................... 33

United States, west-central, index map of............ 7

Upper Wyoming beds, correlation of .................. 21

occurrence of...................................... 16-17

V.

Veto Pass, fossils from................................. 19-20

Von Schultz & Low, analysis by....................... 80-81

W.

Walcott, C. D., fossil determined by................... 36

on Ordoviciaii rocks............................... 14

section by ......................................... 41

Walsenburg, well at, data on .......................... 70

Water, underground, analyses of...................... 80-81

depth to........................................... 74-75

map showing ............................... Pocket.

derivation of .................................... 7,73-74

Page. 

Water, description of.................................. 60-84

head of ...................................... 50-51,76-77

map showing.................................. 76

occurrences of, description of..................... 50-84

quality of........................'.................. 80-82

quantity of ........................................ 77-79

Water hole, view of.................................... 44

Watervale, well at, data on-........--....-......----.. 67-68

Weller, Stuart, fossils examined by.................... 15, IS

Wells, H.L.,analyses by............................... 80-81

Wells, artesian, area of ................................ 75-76

descriptions of..................................... 52-68

development of.................................... 7

head in............................................ 76-77

relations of, map showing......................... 50

views of............................................ 64,62

Wells, dry, descriptions of............................. 68-73

Wells, flowing, descriptions of......................... 62-62

Wells, nouflowing, descriptions of..................... 62-68

Wet Mountains, rocks on, map and cross sections of .. 46 

Wetmore, well at, data on............................. 68

well near, head in................................. 77

White, C. %A., on Morrisou fossils....................... 22

White Elver group, deposition of...................... 49

occurrence of...._.....................-............. 12

Wykofl Park, well at, data on......................... 53

Wyoming formation, correlation of.................... 21

z.

Zaphrentis sp., occurrence of.......................... 18,20