ACKNOWLEDGMENTS
This guidebook was written at the request of the Colorado Geological Survey to fulfill a long-felt need for a popular account of the state’s geology and its relationship to Man.
The authors wish to thank those of their colleagues who have assisted at various times in the preparation of this book. John Rold, Colorado State Geologist, and William Weber, of the University of Colorado Museum staff, made many helpful suggestions concerning the manuscript. John Schooland, vice president of the Colorado Historical Society, generously provided several pictures of early mining activities in Colorado. Permission to reproduce drawings and paintings of fossils and reconstructions of past environments was granted by the American Museum of Natural History and the University of Colorado Museum. Drawings, maps, and diagrams are largely the work of Robert Maurer, who also designed the cover and title page.
Tilted dark red sedimentary rocks of the Pennsylvanian-Permian Maroon Formation are well exposed in the cliffs of Maroon Bells, southwest of Aspen. (Photo courtesy Hydraulic Unlimited Mfg. Co.)
CONTENTS
Page [Introduction] 1 [I Colorado’s Three Provinces] 3 [The Prairies] 8 [The Peaks] 10 [Front Range] 11 [Wet Mountains] 16 [Sangre de Cristo Range and Spanish Peaks] 17 [Park Range and Rabbit Ears Range] 19 [Gore Range] 20 [Tenmile and Mosquito Ranges] 21 [Sawatch Range] 22 [Elk Mountains and West Elk Mountains] 24 [San Juan Mountains] 25 [Uinta Mountains] 26 [The Plateaus] 28 [II Geologic History of Colorado] 32 [Precambrian Era] 33 [Paleozoic Era] 38 [Cambrian Period] 39 [Ordovician Period] 40 [Silurian Period] 42 [Devonian Period] 42 [Mississippian Period] 43 [Pennsylvanian Period] 44 [Permian Period] 48 [Mesozoic Era] 51 [Triassic Period] 51 [Jurassic Period] 52 [Cretaceous Period] 56 [Cenozoic Era] 59 [Tertiary Period] 59 [Quaternary Period] 68 [III Geology and Man in Colorado] 74 [Gold, Silver, and Other Metals] 77 [Boulder County] 79 [Central City and Idaho Springs] 80 [Georgetown, Empire, and Silver Plume] 81 [Leadville] 82 [Breckenridge] 83 [Fairplay] 84 [Silverton] 85 [Ouray] 87 [Aspen] 88 [Creede] 89 [Cripple Creek] 90 [Climax] 91 [Radium, Uranium, and Vanadium] 93 [Oil, Natural Gas, and Oil Shale] 94 [Coal] 96 [Construction Materials] 97 [Sand, Gravel, and Clay] 97 [Stone] 99 [Lime and Gypsum] 101 [Gems] 102 [Water] 103 [Surface Water] 103 [Groundwater] 105 [Caves] 106 [Springs] 109 [Environmental Geology] 111 [Glossary] 114 [Suggested Reading] 119 [Index] 121
ILLUSTRATIONS
Page [Colorado’s three geologic provinces] 2 [Pikes Peak, seen from the Garden of the Gods] 4 [Rock classification (chart)] 5 [Stratigraphic column (chart)] 7 [Jurassic rocks in Colorado (map)] 9 [East face of Longs Peak] 11 [Rocky Mountain National Park (east-west profile)] 12 [Big Thompson Canyon, west of Loveland] 13 [Red Rocks Amphitheater, west of Denver] 14 [Colorado Springs area (map and cross section)] 15 [Joint systems in Precambrian rocks, Boulder Canyon] 15 [Spanish Peaks, southwest of Walsenburg] 18 [Hahn’s Peak, north of Steamboat Springs] 19 [Gore Range from the east] 20 [Aspen Mountain geology (map)] 23 [Mt. Sopris, south of Glenwood Springs] 24 [Ouray, in the San Juan Mountains] 25 [Steamboat Rock, Dinosaur National Monument] 27 [Grand Hogback, near Rifle (block diagram)] 28 [Mt. Garfield, near Grand Junction] 30 [Precambrian-Cambrian unconformity south of Ouray] 34 [Geologic map of Colorado] 35 [Black Canyon of the Gunnison National Monument] 36 [Precambrian-Cambrian unconformity, Glenwood Canyon] 38 [Cambrian fossils] 39 [Ordovician fossils] 41 [Devonian fossils] 43 [Mississippian fossils] 44 [Pennsylvanian paleogeography (map)] 45 [Fountain Formation northwest of Denver] 45 [Pennsylvanian fossils] 46 [Contorted Pennsylvanian rocks near Gypsum] 46 [Balanced Rock, Garden of the Gods] 48 [Permian reptile tracks] 49 [The Flatirons, near Boulder] 50 [Colorado National Monument] 51 [Morrison Formation, west of Denver] 53 [Dinosaur bones, found near Morrison] 54 [Dakota Sandstone hogback] 56 [Cretaceous fossils] 57 [Wolford Mountain, north of Kremmling] 60 [Eohippus, the “Dawn Horse”] 61 [Golden and South Table Mountain] 62 [Devil’s Staircase, near Spanish Peaks] 63 [Green River oil shale, west of Rifle] 64 [Florissant Fossil Beds National Monument] 65 [Pawnee Buttes, north of Fort Morgan] 66 [Fossil mammals, northeastern Colorado] 67 [Glacial lakes in Rocky Mountain National Park] 68 [Arapaho Glacier, west of Boulder] 70 [Pleistocene mastodons] 72 [Great Sand Dunes National Monument] 73 [Colorado Mineral Belt (map)] 78 [Sluicebox mining in early Colorado] 81 [Early-day Leadville] 82 [Gold dredge, Fairplay] 84 [Silverton, in the San Juan Mountains] 86 [Abrams Mountain, south of Ouray] 87 [Creede and its mines (map)] 89 [Cripple Creek, near Pikes Peak] 90 [Climax molybdenum mine (cross section)] 91 [Rampart Range quarry, near Colorado Springs] 98 [Yule Marble quarry, near the town of Marble] 99 [Lyons Sandstone quarry] 100 [University of Colorado Museum] 100 [Colorado-Big Thompson Project (cross section)] 103 [San Luis Valley (cross section)] 105 [Cave of the Winds, near Manitou] 107 [Mesa Verde cave and Indian dwellings] 108 [Glenwood Hot Springs] 109