NAMES OF MINES.

Location indicated on the map by numbers. NUMERICAL LIST. ALPHABETICAL LIST.

1. Johnny Bull. 79. Alma Mater. A. B. G., 31. Little Maggie Shaft, 99. 2. Gold Anchor Tunnel. 80. Phoenix No. 1 Level. Air shaft, 147. Logan No. 2 Shaft, 38. 3. Albion. 81. Pelican. .Albion, 3. Logan Shaft, 44. 4. Caledonia Shaft. 82. Last Chance". Allegheny, 97. Logan Tunnel (site), 37. 5. Utah. 83. Phoenix No. 4 Level. Alma Mater, 79. Logan Tunnel, 56. 6. Marriage Stake. 84. Nellie Bly Lower Tunnel. Argentine, 92. M. A. C. Lower Tunnel, 25. 7. Hand-out Shaft. 65. Nellie Bly Upper Tunnel. Argonaut, 124. M. A. C. Upper Tunnel, 24. 8. Golden 1900. 86. Eureka. Aspen Shaft, 155. Magnet, 64. 9. Belzora. 87. Old Butler Tunnel. Atlantic Cable, 72. Marriage Stake, 6. 10. San Juan. 88. Hope and Cross. Aztec, 61. Mediterranean, 95. " , 11. Zenith. 89. Bourbon. Bancroft, 121. M. M V P., 53. 12. Christina Shaft. 90. Uncle Ned. - Bancroft Shaft, 120. Mohawk, 20. 13. Lackawanna. 91. Worlds Fair. Belzora, 9. Monterey, 40. 14. Flying Fish. 92. Argentine. Black Hawk, 96>.' Montezuma, 74. 15. Flying Fish Upper Tunnel. 93. Iron. Blaine and Logan Tunnel, 35. Montezuma Shaft, 153. 16. Southern Consolidated Tunnel. 94. Laxy. . Bourbon, 89. Mountain Spring Tunnel, 49. 17. Puzzler. 95. Mediterranean. Caledonia Shaft, 4. N. A. Cowdrey, 127. 18. Petzite. 96. Black.Hawk. California, 62. Nellie Bly Lower Tunnel, 84. 19. Great Western. 97. Allegheny. Calumet, 75. Nellie Bly Upper Tunnel, 85. 20. Mohawk. 98. Lelia Davis. C. A.R.,57. Old Butler Tunnel, 87. 21. Hess and Garren Tunnel. 99. Little Maggie Shaft. C. H. C. Shaft, 46. Onamo Tunnel, 114. 22. Puzzle Extension (incline). 100. Wildcat Tunnel. C. H. C. Tunnel, 47. Ontario, 27. 23. Puzzle (main shaft). 101. Privateer. Chestnut, 137. Pelican, 81. 24 M. A. C. Upper Tun neL 102. Sunflower. Chestnut (old tunnel), 138. Petzite, 18. 25. M. A C. Lower Tunnel. 103. Forest- Payroll. Christina Shaft, 12. Phoenix No. 1 Level, 80. 26. Hoosier Girl Shaft. 104. Union-Carbonate Shaft. Cobbler Shaft, 78. Phoenix No. 4 Level, 83. 27. Ontario. 105. Union-Carbonate Tunnels. Columbia, 60. Pigeon, 36. 28. Dolly Tunnel. 106. Fickle Goddess Tunnel. Crebec Shaft, 51. Pigeon Shaft, 45. 29. J. E. Watson Tunnel. 107. South-Park. C. V. G.,32. Pr-inceton. 52. 30. Governor. 108. Fortune and Duncan. Deep Shaft, 130. Privateer, 101. 31. A. B. G. 109. Eighty-eight. Derby and Evans Shaft, 122. Pro Patria Tunnel, 112. 32. C. V. G. 110. Iron Dollar. Dolly Tunnel, 28. Puzzle Extension Incline, 22. 33. Hureka. 111. Hibernia. Durango, 149. Puzzle Main'Shaft, 23. 34. Wabash. 112. Pro Patria Tunnel. Eagle, 67. Puzzler, 17. 35, Blaine and Logan Tunnel. 113. Revenue Return. Eighty-eight, 109. Revenue Return, 113. i 36. Pigeon. 1 14. Onamo Tunnel. Enterprise Group Tunnel, 142. Riverside, 73. 37. Logan Tunnel. 115. Sceptical Shaft. Enterprise Shaft, 150. Roger Tichborne Shaft, 43. 38. Logan No. 2 Shaft. 1 16. Golden Fleece. Eureka, 65. Sambo, 58. 39. Leap Year. 117. Whim. Eureka, 86. San Juan, 10. 40. Monterey. 118. Western Tunnel. Fickle Goddess Tunnel, 106. Sceptical Shaft, 115. 41. Silver Wing. 119. Ironclad. Flying Fish, 14. Shamrock, 70. 42. Undine. 120. Bancroft Shaft. Flying Fish Upper Tunnel, 15. Shehocton, 133. 43. Roger Tichborne Shaft. 121. Bancroft. Forest-Payroll, 103. Silver Age, 143. 44. Logan Shaft. 122. Derby and Evans Shaft Fortune and Duncan, 108. Silver Glance Shaft, 156. 45. Pigeon Shaft. 123. St. Louis Shaft. Futurity Tunnel, 76. Silver Swan, 128, 46. C. H. C. Shaft. 124. Argonaut. Gold Anchor Tunnel, 2. Silver Wing, 41. 47. C. H. C. Tunnel. 125. Little Maggie Group. Golden Fleece, 116. Smuggler, 71. 48. Limestone Tunnel. 136. Tomale. Golden 1900, 8. Songbird Shaft, 151. 49. Mountain Spring Tunnel. 127. N. A. Cowdrey. Governor, 30. Southern Tunnel, 132. 50. Wellington Shaft. 128. Silver Swan. Grand View Incline, 77. Southern Consolidated Tunnel, 16. 51. Crebec Shaft. 129. Trinadad. Great Western, 19. South Park, 107. 52. Princeton. 130. Deep Shaft. Hand-out Shaft, 7. .St. Louis Shaft, 123. 53. M. M. P. 131. Stephanite Tunnel. Hess and Garren Tunnel,.21. Stanley Shaft, 146. 54. Iron Giant. 132. Southern Tunnel. Hibernia, 111. Stephanite Tunnel, 131. 55 Lily D. 133. Shehocton. Hoosier Girl Shaft, 26. Stephens, 136. 56. Logan Tunnel (site). 134. Syndicate Tunnel. Hope and Cross, 88. Stephens (old tunnel), 135. 57. C. A. R. . 135. Stephens (old tunnel). Hureka, 33. Sunflower, 102. 58. Sambo. 136. Stephens. kon, 93. Swansea, 140. 59. Lake View. 137. Chestnut. Ironclad, 119. Syndicate Tunnel, 134. 60. Columbia. 128. Chestnut (old tunnel). Iron Dollar, 110. Tomale, 126. 61. Aztec. 139. Klingender. Iron Giant, 54. Trinadad, 129. 62. California. 140. Swansea. Isabella Shaft, 145. Uncle Ned, 90. 63. Zulu Chief. 141. Lexington Tunnel. J. E. Watson Tunnel, 29. :: Uncle Remus Shaft, 66. 64. Magnet. 142. Enterprise Group Tunnel. Johnny Bull, 1. Undine, 42. 65. Eureka. 143. Silver Age. Jumbo Shaft, 152. Union-Carbonate Shaft, 104. 66. Uncle Remus Shaft. 144. Wakeman Tunnel. Klingender, 139. Union-Carbonate Tunnels, 105. 67. Eagle. 145. Isabella Shaft. Lackawanna, 13. Utah, 5. 68. Little Leonard, 146. Stanley Shaft. Lake View, 59. Vestal Shaft, 154. 69. Yankee Boy. 147. Air shaft. Last Chance, 82. Wabash, 34. 70. Shamrock. 148. Laura Shaft. Laura Shaft, 148. Wakeman Tunnel, 144. 71. Smuggler. 149. Du range. Laxy, 94. Wellington Shaft, 50. 72. Atlantic Cable. 150. Enterprise Shaft. Leap Year, 39. Western Tunnel, 118. 73. Riverside. 151. Songbird Shaft. Lelia Davis, 98. Whim, 117. 74. Montezuma. 152. Jumbo Shaft. Lexington Tunnel, 141; Wildcat Tunnel, 100. 75. Calumet. 153. Montezuma Shaft. Lily D., 55. Worlds Fair, 91. 76. Futurity Tunnel. 154. Vestal Shaft. Limestone Tunnel, 48. Yankee Boy, 69. 77. Grand View Incline. 155. Aspen Shaft. Little Leonard, 68. Zenith, 11. 73. Cobbler Shaft. 156. Silver Glance Shaft. Little Maggie Group, 125. Zulu Chief, 63. ' DLUMHA] iTIO

GENERALIZED SECTION FOR THE RICO QUADRANGLE. SCALE : 1 INCH = 400 FEET.

SYSTEM. SERIES. COLUMNAR THICKNESS CHARACTER OF FORMATIONS. FORMATION NAME. SYMBOL. SECTION. IN FEET.

=.-=ZZ -" -" "

' ' - ' '- *-*=-- CO D Soft, dark-grav, or almost black, carbonaceous clay shale containing thin lenses or concretions of O UPPERCRETACEOUS Mancos shale. Km 1000+ impure limestone. Embraces the Colorado group and a portion of the Pierre division of the u Montana. Fossils occur more or less abundantly at several horizons. O -'- ^-^- h- LLl DC O

.VV.'.S-.l-'.-Tl-'-'i-'.f'^--"'*.' Gray or rusty brown quartzose sandstone or quartzite with a variable conglomerate, containing Dakota sandstone. Kd 100-250 small chert* pebbles at or near the base. Carbonaceous shale partings occur at several horizons and coal of poor quality is locally present. Indistinct fossil leaves occur sparingly.

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'.' '.' ' '. '. ' '. '. ".'.' ' ' ..'. ;. ; A complex of alternating friable, fine-grained, yellowish or grayish sandstones and shales. The , , , , , , _ sandstones are seldom more than 20 feet thick. They often include flakes of grayish clay or 0 McElmo formation. Jme ':' ''.'''' .'' '. ^- ' '.' ' ' " 400-1000 shale. The shales are chiefly green in color, but may be pink, dark red, or chocolate brown. Some shale layers are sandy and others highly calcareous. No fossils have been found in the CO McElmo strata. CO .V.-/...... A......

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Consists principally of two massive, friable, white sandstone beds, with a narrow band of dark limestone or calcareous shale between them. The sandstones are quartzose, of even grain, dis­ La Plata sandstone. Jlp 250-500 tinctly cross bedded, and form massive cliffs where exposed. The limestone or calcareous shale is locally brecciated or recemented. No determinable fossils have been found.

UNCONFORMITY :.^TT^T- ! .'.'. .VrTfr. :T^ C-- tRIASSIC Sandy marl and fine-grained sandstone and shale of bright-red color with fine limestone con­ "Ed glomerate near the base, in which are found teeth of a crocodile (Belodon) and of a megalosau- Dolores formation. OOOOoc. 0 o'^o'n-'b °.90 00° 400 roid dinosaur, with a rare gasteropod shell similar to mmparus, indicating the Triassic age of ^^ o-y.ooc^ooc. the formation,

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*c 9*. P;*o*-« ft. 6;J »*5' » o'd : eo cj'-.oo c~- «*: A complex of bright-red sandstones and lighter red or pinkish grits and conglomerates alternating E Cutler formation. Cc 1600 with sandy shales and earthy or sandy limestones of varying shades of red. cc ^>?jr;v??»°:^:o:^:°. ? LLJ 0_ o«:o.;i oio-i 66vo''6?':

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CO ^^^^ D ^^^^ O DC _Lt-..'i'. -i .'.' ' ' '...i.. ,irj Dark reddish-brown sandstone and pink grit, with intercalated greenish or reddish shale and LU Rico formation. Cr 300 sandy, fossiliferous limestone.

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"i "i ' ! i -' UNCONFORMITY i i 11 w ^,-^-^-r^r- Dull yellow to buff, compact limestone, lower third shaly with thin quartzites. Abundant fossils 6z Ouray limestone. DCo i i i j 100-300 indicate Devonian age of lower two-thirds and Mississippian age of upper part. s=>«c i t i- i . UNCONFORMITY Quartzite, massive and conglomeratic in lower part, thin bedded with shale and sandy partings Ignacio quartzite. Ci ^;^;:;.:v:.;.;;:;V^:: 0-200 in medial zone, succeeded by more massive quartzite. Light gray, pink, or yellow predomi­ A°s nates. One shell, obolus sp. ?, has been found near the middle of the formation. UNCONFORMITY

ALGONKIAN White or smoky quartzite and dark slate, mainly massive, but in a few places alternating in Dnconipahgre formation. Au ^ thinner layers. No fossils have been found. WHITMAN CROSS, ARTHUR C. SPENCER, Geologists. U. S. GEOLOGICAL SURVEY COLORADO CHARLES D. WALCOTT, DIRECTOR RICO QUADRANGLE

FIG. 1.-THE SOUTHEASTERN PEAKS OF THE RICO MOUNTAINS, FROM THE WEST SIDE OF THE DOLORES RIVER. FIQ. 2.-SANDSTONE MOUNTAIN, LOOKING ACROSS THE DOLORES FROM THE FOOT OF C. H. C. HILL.

In the center, on the sky line, is the porphyry cap of Dolores Peak, behind which rises Blackhawk Peak. Farther to the left is the north shoulder The view illustrates the character of cliff exposures formed by the alternating limestone, sandstone, and shale beds of the Hermosa formation, and of Blackhawk Peak, with its light-colored porphyry cliffs. On the right is Whitecap Mountain, with its porphyry sheets, and in front of it the similar ones of the lower portion of the Dolores red beds in the knolls to the right. The crevice crossing the summit of Sandstone Deadwood Gulch. Across the face of Dolores Mountain may be traced the limestone ledges in the middle of the Hermosa formation. Mountain marks the line of a small fault.

FIG. 3.-DARLING RIDGE AND HORSE GULCH, FROM SANDSTONE MOUNTAIN. FIG. 4.-TORRENTIAL FAN AT THE MOUTH OF AZTEC GULCH, FROM EAST SIDE OF THE DOLORES RIVER.

At the head of Horse Gulch, on the right, is Calico Peak, and on the left Anchor Mountain. The snow-covered slope of Darling Ridge on the left, Shows the characteristic form and grade of a torrential fan. The face at the bottom of the main fan is an erosion scarp cut by the river. A from the creek to the forested crest, is wholly occupied by landslide debris. The Puzzle mine is situated at the foot of the snowy slope, in a secondary fan is now being formed in front of that scarp. landslide block.

FIG. 5.-TELESCOPE MOUNTAIN AND THE UPPER PART OF C. H. C. HILL, FROM SANDSTONE MOUNTAIN. FlG. 6.-DETAILS OF LANDSLIDE TOPOGRAPHY IN THE AREA ON THE NORTH SIDE OF HORSE GULCH. The highest point isthe summit of Telescope Mountain. Onthel eft is a scarp of Hermosa and Rico strata. Onthe right is the ridge leading down to Nigger Baby Hill. The foreground and central part of the view show the landslide topography of C. H. C. Hill. The Pigeon vein, or " big fissure," runs beneath The view shows characteristic landslide trenches, ridges, and mounds, where disintegration the snow-covered bench. The Pigeon mine buildings in foreground. has smoothed out the originally more angular forms of slide blocks. In the background are strongly contrasting ledge outcrops,