Tennantite. A metallic gray mineral that contains copper, iron, and arsenic, and is an ore of copper.

Tetrahedrite. A brittle, dark gray to black, metallic mineral containing copper, iron, zinc, and silver.

Trilobite. One of a primitive group of extinct marine crustaceans, related to crabs and lobsters, having segmented bodies divided by longitudinal grooves into three lobes.

Unconformity. A surface separating layers of rock, formed by a period of nondeposition or erosion.

Vein. A crack or fissure filled with mineral material, often with valuable ore minerals.

SUGGESTED READING

There are thousands of scientific articles and books on Colorado geology, and many new ones appear each year. Following is a selection of books and booklets which we believe will be most useful and interesting in extending your knowledge of the state’s geology.

Donnell, John R., editor, 1960, GEOLOGICAL ROAD LOGS OF COLORADO. Rocky Mountain Association of Geologists, Denver. Itineraries for a number of geological trips along Colorado highways and byways.

Eckel, Edwin B., 1961, MINERALS OF COLORADO, A 100-YEAR RECORD. U. S. Geological Survey Bulletin 1114.

Emmons, S. F., Cross, Whitman, and Eldridge, G. H., 1896, GEOLOGY OF THE DENVER BASIN IN COLORADO. U. S. Geological Survey Monograph 27. The classic early treatment of the surface geology around Denver, with many historic illustrations.

Hansen, Wallace R., 1965, THE BLACK CANYON OF THE GUNNISON TODAY AND YESTERDAY. U. S. Geological Survey Bulletin 1191. A readable account of this unusual national monument near Montrose.

Hansen, Wallace R., 1969, THE GEOLOGIC STORY OF THE UINTA MOUNTAINS. U. S. Geological Survey Bulletin 1291. The eastern part of this range is in Colorado.

Henderson, C. W., 1926, MINING IN COLORADO, A HISTORY OF DISCOVERY, DEVELOPMENT AND PRODUCTION. U. S. Geological Survey Professional Paper 138.

Lee, W. T., 1917, THE GEOLOGIC STORY OF THE ROCKY MOUNTAIN NATIONAL PARK, COLORADO. U. S. National Park Service Publication. An old report, not adequately superseded.

Lovering, T. S., and Goddard, E. N., 1950, GEOLOGY AND ORE DEPOSITS OF THE FRONT RANGE, COLORADO. U. S. Geological Survey Professional Paper 223. A comprehensive study of mineral-bearing areas in the Front Range.

Lohman, S. W., 1965, THE GEOLOGIC STORY OF COLORADO NATIONAL MONUMENT. Colorado and Black Canyon Natural History Association, Grand Junction.

Pearl, Richard M., 1956, NATURE AS SCULPTOR: A GEOLOGIC INTERPRETATION OF COLORADO SCENERY. Denver Museum of Natural History Popular Series No. 6, Revised Edition.

Pearl, Richard M., 1969, EXPLORING ROCKS, MINERALS, FOSSILS IN COLORADO. Swallow Press, Revised Edition.

Pearl, Richard M., 1971, COLORADO GEM TRAILS AND MINERAL GUIDE. Swallow Press, 3rd Edition.

Powell, John Wesley, 1876, REPORT ON THE GEOLOGY OF THE EASTERN PORTION OF THE UINTA MOUNTAINS AND A REGION OF COUNTRY ADJACENT THERETO. U. S. Geological and Geographical Survey of the Territories. One of the earliest accounts of geology in Colorado, written by the explorer of the Colorado River and the father of the U. S. Geological Survey.

Rabbit, Mary C., and others, 1969, THE COLORADO RIVER AND JOHN WESLEY POWELL. U. S. Geological Survey Professional Paper 669. A resumé of part of Powell’s work and a good discussion of the geologic history of the entire Colorado River, which begins near Grand Lake.

Richmond, Gerald M., 1965, GLACIATION OF THE ROCKY MOUNTAINS. A part of THE QUATERNARY OF THE UNITED STATES, Princeton University Press. A summary of current knowledge of glaciation in Colorado and surrounding areas.

Rodeck, Hugo G., editor, 1964, NATURAL HISTORY OF THE BOULDER AREA. University of Colorado Museum Leaflet No. 13. Contains articles on geology and biology.

Untermann, G. E., and Untermann, B. R., 1954, GEOLOGY OF DINOSAUR NATIONAL MONUMENT AND VICINITY, UTAH—COLORADO. Utah Geological and Mineralogical Survey Bulletin 42. A detailed study of the eastern Uinta Mountains.

Weimer, Robert J., and Haun, John D., editors, 1960, GUIDE TO THE GEOLOGY OF COLORADO. Geological Society of America, Rocky Mountain Association of Geologists, and Colorado Scientific Society, Denver. A concise summary of many aspects of Colorado geology, this guide includes several geological itineraries and many reference listings.

Wolle, Muriel Sibell, 1949, STAMPEDE TO TIMBERLINE, Sage Books. An excellent account of early mining activity in the state, with many fine drawings of the early settlements.

INDEX

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A
Abrams Mountain, 87
Alamosa, 35
Alamosa Formation, 67, 105, 106
Alma, 78
Ancestral Rocky Mountains, 44, 45
Animas River, 58, 86
Ankareh Formation, 52
Antero Junction, 21
Anthracite, 97
Arapahoe Conglomerate, 60
Arapaho Glacier, 70, 71
Arkansas Hills, 21
Arkansas Mountain, 79
Arkansas River, 3, 22, 35, 90
Arkansas Valley, 21
Aspen, Front., 1, 22, 35, 50, 74, 77, 78, 88-89
Aspen Mountain, 23, 88
Avon, 22
B
Battlement Mesa, 62
Belden Formation, 44, 109
Benton Shale, 57
Berthoud Pass, 12, 92
Big Thompson Canyon, 12, 71
Big Thompson River, 69, 103, 104
Black Canyon of the Gunnison, 36, 37, 44, 71, 105
Black Hawk, 14, 77, 78, 79, 80
Blue River, 103
Book Cliffs, 29
Boulder, 8, 14, 33, 45, 47, 48, 50, 71, 74, 75, 94, 98, 99, 100, 101
Boulder County, 78, 79
Boulder Creek, 1, 15, 71, 103
Boulder Creek Granite, 14, 33, 35
Boulder Reservoir, 103
Breckenridge, 1, 78, 83-84
Bross, Mt., 21
Buena Vista, 22
Buffalo Peaks, 21
Building stone, 24, 48, 50, 99-101
C
Cache la Poudre River, 66, 103
Cambrian, 7, 34, 39
Camp Bird, 78, 88
Canon City, 3, 11, 16, 52, 53, 75, 94
Canon City Embayment, 16
Carbondale, 97
Carboniferous, see Mississippian, Pennsylvanian
Cardiff, 97
Carmel Formation, 52
Carter Lake, 103
Castle Creek, 88
Castle Rock, 8, 61, 112
Castle Rock Conglomerate, 60
Cave of the Winds, 106, 107
Caves, 31, 106-108
Cenozoic (see also Tertiary, Quaternary), 7, 16, 18, 26, 28, 29, 59-73, 109
Central City, 1, 14, 74, 77, 78, 80
Chaffee Formation, 42
Cherry Creek, 1
Cheyenne Mountain, 14, 15, 110
Cheyenne Sandstone, 105
Chinle Formation, 51, 52, 93, 101
Clay, 75, 97-99
Clear Creek, 1, 71, 80
Climax, 21, 78, 91-92
Climax Granite Porphyry, 91, 92
Coal, 23, 75, 96-97
Coal Creek, 14, 15
Coal Creek Quartzite, 33
Coaldale, 97
Coalmont, 97
Cokedale, 97
Collegiate Range, 22
Colorado National Monument, 29, 31, 44, 51, 108
Colorado River, 3, 20, 21, 28, 29, 35, 39, 103, 104, 105, 108, 109
Colorado Springs, 14, 15, 35, 37, 48, 97, 98, 109
Columbia, Mt., 22
Como, 78, 97
Construction materials, 97-102
Copper, 74, 75, 80, 81, 83, 89, 91
Creede, 65, 78, 89-90
Crested Butte, 24, 97
Cretaceous, 7, 12, 20, 23, 29, 30, 53, 56-58, 94, 95, 97, 98, 101, 105, 108, 110
Cripple Creek, 1, 74, 77, 78, 90-91
Cross Mountain, 26, 29
Crystal River, 24, 99
Culebra Range, 17
Curecanti, 105
Curtis Formation, 52
D
Dakota Formation, 12, 51, 53, 56, 94, 97, 105
Dawson Arkose, 60
Dawson Butte, 112
Delcarbon, 97
Democrat, Mt., 21
Denver, 3, 8, 14, 33, 35, 37, 45, 47, 48, 52, 53, 60, 74, 83, 94, 96, 99, 100, 104, 112, 113
Denver Basin, 8, 75, 94, 95
Denver Formation, 60, 62
Devonian, 7, 42-43, 83
Dillon, 104
Dinosaur National Monument, 27, 53, 55
Durango, 25, 28, 35, 47, 58, 78, 85, 102
Dyer Dolomite, 42
E
Eagle, 47, 101, 106
Eagle River, 22, 47
Edwards, 22
Elbert, Mt., 22
Eldorado Springs, 109
Elk Mountains, 24, 69
Empire, 1, 78, 81
Englewood, 113
Entrada Sandstone, 51, 93
Environmental geology, 111-113
Eocene, 64
Estes Lake, 103
Estes Park, 69, 104
Evans, Mt., 3, 12
F
Fairplay, 78, 84-85
Fairy Cave, 107
Flattop Mountain, 19
Floods, 112-113
Florence, 74, 94
Florissant Fossil Beds National Monument, 65
Fort Carson, 15
Fort Collins, 35, 101, 102
Fountain Formation, 12, 14, 45, 47, 48
Fox Hills Sandstone, 58
Fremont Limestone, 40, 41
Frisco, 21
Front Range, 11-16, 33, 35, 44, 50, 51, 52, 56, 60, 61, 68, 69, 70, 71, 93, 99, 101, 103, 107, 109
Frying Pan River, 105
Fulford, 107
Fulford Cave, 106
G
Garden of the Gods, 4, 14, 15, 47, 48
Garfield, Mt., 30
Gas, natural, 1, 28, 75, 94-96
Gems, 75, 102
Gem Village, 102
Georgetown, 78, 81
Gilman, 21
Gilpin County, 78
Glen Eyrie Formation, 44
Glenwood Canyon, 37, 39
Glenwood Springs, 24, 29, 35, 99, 107, 109
Gold, 1, 22, 29, 74, 75, 77-91
Golden, 8, 14, 62, 74, 78, 83, 93, 98, 111
Gold Hill, 1, 74, 78, 79
Gore Creek, 47
Gore Pass, 19, 20
Gore Range, 20-21, 35, 69
Gore Range-Eagle’s Nest Wilderness Area, 20, 21
Granby, 20, 62
Granby Lake, 103
Grand Hogback, 28, 29
Grand Junction, 29, 30, 35, 55
Grand Lake, 12, 69, 103, 104
Grand Mesa, 35, 62
Grand Valley, 25
Gravel, 75, 97-99
Great Sand Dunes National Monument, 17, 18, 73
Green River, 27, 103
Green River Basin, 4
Green River Canyon, 31
Green River Formation, 64, 95-96
Greenhorn Formation, 101
Greenhorn Peak, 16
Groundwater, 76, 105-106
Gunnison, 35
Gunnison, Black Canyon of the, 36, 37, 44, 71, 105
Gunnison River, 35, 36, 37, 105
Gypsum (mineral), 22, 30, 75, 101-102
Gypsum (town), 47, 101
Gypsum Valley, 30, 47, 101
H
Hahn’s Peak, 19
Harding Sandstone, 40, 41
Harvard, Mt., 22
Hayden, 96, 97
Hayden Pass, 17
Hermosa Formation, 45, 47
Hidden Valley, 69
Horseshoe Amphitheater, 85
Horseshoe Park, 69
Horsetooth Reservoir, 103
Huerfano Basin, 35, 61
I
Ice Age, see Pleistocene
Iceberg Lake, 66
Idaho Springs, 14, 78, 80
Idaho Springs Formation, 33, 92
Independence Pass, 22
Iron, 1, 17, 74
Ironton, 78, 88
J
Jewel Lake, 68
Juniper Mountain, 26, 29
Juniper Springs, 109
Jurassic, 7, 9, 23, 36, 52-55, 93
K
Kremmling, 19, 20, 60
L
La Junta, 8, 35
Lake City, 77, 78
Lake County, 77
Lamar, 8
Landslides, 111-112
La Plata Mountains, 26
Laramide Orogeny, 59, 60
Laramie Formation, 57, 58, 97
Larkspur, 112
La Veta Pass, 17, 18, 37
Lead, 74, 75, 80, 81, 82, 83, 85, 86, 89
Leadville, 1, 22, 77, 78, 82-83
Leadville Limestone, 43, 44, 83, 88, 99, 106, 109
Lime, 75, 101
Lincoln, Mt., 21
Lincoln Porphyry, 21
Lipalian Interval, 7, 36, 39
Littleton, 113
Logan County, 95
Longs Peak, 3, 11, 12, 68
Loveland, 14, 102
Loveland Pass, 12
Lykins Formation, 12, 51, 52, 101
Lyons, 14, 49, 99, 100, 101
Lyons Sandstone, 12, 48, 49, 50, 99, 100, 101
M
Magnolia, 79
Mancos Shale, 30, 95
Manitou, 39, 106, 107, 110
Manitou Formation, 40, 41, 110
Manitou Springs, 109
Marble, 24, 99
Marble Mountain, 106
Maroon Bells, Front., 24, 50
Maroon Creek, 24
Maroon Formation, 50
Mary’s Lake, 103
Massive, Mt., 82
McDermott Formation, 58
Mesa de Maya, 8, 35, 62
Mesa Verde, 28, 29, 35
Mesa Verde Formation, 30, 58, 108
Mesa Verde National Park, 31, 71, 108
Mesozoic (see also Triassic etc.), 7, 10, 11, 12, 14, 15, 26, 28, 51-58, 60, 93
Mestas, Mt., 17
Middle Park, 4, 16, 35, 61
Million Dollar Highway, 87, 88
Mills Lake, 68
Milner Pass, 66
Minturn, 39
Minturn Formation, 45, 46, 47
Miocene, 66, 67, 87
Mississippian, 6, 7, 43-44, 83, 106, 109
Moenkopi Formation, 52
Molas Formation, 44
Molas Lake, 25
Molybdenum, 1, 74, 75, 76, 77, 91-92
Monarch Pass, 23
Morgan County, 95
Morrison, 53, 54, 55
Morrison Formation, 12, 36, 51, 53, 55, 93
Mosca Pass, 17, 73
Mosquito Pass, 85
Mosquito Range, 21, 22, 35, 39, 69
Mountain Province, 3, 4, 10-27, 35, 46, 93, 94, 101, 102, 103, 109, 111
Mt. Bross, 21
Mt. Columbia, 22
Mt. Democrat, 21
Mt. Elbert, 22
Mt. Evans, 3, 12
Mt. Garfield, 30
Mt. Harvard, 22
Mt. Lincoln, 21
Mt. Massive, 82
Mt. Mestas, 17
Mt. Princeton, 22
Mt. Princeton Hot Springs, 22, 110
Mt. Sneffels, 87, 88
Mt. Sopris, 24
Mt. Yale, 22
Mt. Zirkel, 19
Music Pass, 17, 73
N
Navajo Sandstone, 52
Nederland, 78, 79
Needle Mountains, 26
Niobrara Formation, 57, 101
North Park, 4, 16, 35, 58, 61, 94, 97
O
Oil, 1, 29, 30, 75, 76, 94-96
Oil Creek, 94
Oil shale, 95-96
Oligocene, 66, 67
Ordovician, 7, 40-41, 83, 106
Orient, 17
Oro, 82
Otero County, 105
Ouray, 4, 25, 26, 34, 42, 78, 87-88
Ouray Formation, 42
P
Pagoda Mountain, 68
Pagosa Springs, 102, 109
Paleozoic (see also Cambrian etc.), 7, 10, 11, 12, 14, 15, 17, 21, 22, 24, 26, 27, 28, 30, 34, 37, 38-50, 60, 64, 77, 95, 98, 106, 107
Paradox Basin, 4, 47, 95, 101
Paradox Valley, 30, 101
Park Range, 19-20, 35, 69
Parting Sandstone, 42
Pawnee Buttes, 9, 66, 67
Peak Province, see Mountain Province
Peat, 75
Pennsylvanian, Front., 6, 7, 14, 23, 44-47, 48, 50, 83, 95, 101, 106, 109
Permian, Front., 7, 23, 48-50, 95, 99, 100, 101
Petroleum, 1, 29, 30, 75, 76, 94-96
Phosphoria Formation, 50
Piceance Basin, 29
Pierre Formation, 57, 94, 98
Pikes Peak, 3, 4, 11, 12, 15, 65, 90, 91, 110
Pikes Peak Granite, 4, 14, 33, 36
Plains Province, see Prairie Province
Plateau Province, 3, 4, 9, 28-31, 35, 46, 71, 75, 93, 94, 96, 101, 103, 107, 110
Platte River, 3
Pleistocene, 7, 8, 25, 59, 68-73, 105, 106
Plum Creek, 112
Poncha Springs, 109
Prairie Province, 3, 8-10, 12, 35, 66, 72, 75, 94, 96, 103, 105
Precambrian, 7, 10, 11, 14, 15, 16, 17, 19, 20, 21, 26, 33-37, 40, 60, 64, 68, 77, 87, 91, 92, 93, 109
Princeton, Mt., 22
Pueblo, 23, 97
Pumice, 75
Purgatoire Formation, 105
Pyrites, 75
Q
Quandary Peak, 21
Quaternary, 7, 8, 25, 59, 68-73, 105, 106
R
Rabbit Ears Pass, 19
Rabbit Ears Range, 20, 35, 62
Radium, 93
Rampart Range, 15, 97, 98
Rangely, 29, 95
Raspberry Mountain, 112
Rattlesnake Reservoir, 103
Raton Basin, 61
Raton Pass, 61
Red Cliff, 39
Red Mountain, 88
Red Mountain Creek, 88
Red Rocks Park, 14, 37, 47
Redstone, 24
Rico, 26
Rico Range, 26
Rifle, 64
Rio Grande, 35
Roan Plateau, 28, 29, 35
Rocky Mountain National Park, 11, 12, 66, 68, 71, 104
Roncarbo, 97
Royal Gorge, 37, 71
Ruedi, 105
S
St. Mary’s Glacier, 71
Salida, 17, 21, 35
Salina, 79
Sand, 75, 97-99
Sangre de Cristo Range, 10, 17-18, 35, 47, 61, 69, 73, 90, 105, 106
San Juan Basin, 95
San Juan County, 78
San Juan Formation, 88
San Juan Mountains, 4, 25-26, 35, 52, 65, 69, 77, 85, 86, 87, 88, 105
San Luis Valley, 4, 35, 44, 61, 67, 73, 96, 106
San Miguel Range, 26
Santa Fe Formation, 67, 105
Sawatch Range, 22-23, 35, 39, 69, 82, 106
Sawatch Sandstone, 34, 39, 40
Sedalia, 61
Shadow Mountain Reservoir, 103
Sierra Blanca, 17, 18
Silurian, 7, 42
Silver, 22, 74, 77-91
Silver Cliff, 16, 77, 78
Silver Plume, 78, 81
Silver Plume Granite, 33, 35
Silverton, 4, 26, 74, 77, 78, 85-86, 88
Sinbad Valley, 101
Sneffels, Mt., 87, 88
Sopris, Mt., 24
South Park, 4, 16, 21, 35, 61, 65, 84, 97
South Platte River, 1, 3, 35, 85, 103, 104, 112, 113
Spanish Cave, 106
Spanish Peaks, 10, 18, 62
Specimen Mountain, 66
Springs, 17, 22, 109-110
Steamboat Springs, 97, 109
Summit County, 77
Sunshine, 79
Sunshine Peak Rhyolite, 87
Swandyke Gneiss, 33
T
Table Mountain, 8, 62, 111
Telluride, 26, 74, 77, 78
Tenmile Gorge, 21
Tenmile Range, 21, 91
Tertiary, 7, 15, 20, 21, 25, 26, 29, 59-67, 73, 77, 83, 87, 88, 89, 90, 91, 92, 93, 95, 96, 97
Tin, 75
Tincup, 22, 77, 78
Trail Ridge Road, 12, 66
Treasure Mountain Granite, 99
Triassic, 7, 23, 51-52, 93, 101
Trinidad, 8, 61, 96, 97
Trout Creek Pass, 21, 22
Tungsten, 1, 74, 75, 79
Tyndall Glacier, 71
U
Uinta Basin, 4, 29, 64, 75, 95
Uinta Mountain Formation, 26
Uinta Mountains, 4, 10, 26-27, 29, 35, 37, 64
Uncompahgre Gorge, 87
Uncompahgre Plateau, 29, 35, 44
Uncompahgre Quartzite, 87
Urad Mine, 92
Uranium, 1, 29, 80, 93
V
Vail, 21, 47
Vail Pass, 21
Valmont, 62
Vanadium, 74, 75, 93
Villa Grove, 17
W
Walden, 20
Walsenburg, 35, 61, 96
Ward, 78
Water, 76, 103-110
Waunita Hot Springs, 109
Weber Sandstone, 95
West Elk Mountains, 24, 35, 69
Wet Mountains, 16, 35, 61, 95
Wet Mountain Valley, 35
Whiskey Creek Pass, 17
White River, 35, 95
White River Formation, 66
White River Plateau, 28, 29, 35, 43, 107, 109
Williams Canyon, 37, 39
Willow Creek Pass, 20
Willow Creek Reservoir, 103
Wingate Formation, 51, 52, 101
Wolcott, 22, 47
Wolford Mountain, 60
Woodland Park, 110
Woods Lake, 107
Y
Yale, Mt., 22
Yampa River, 3, 27, 31, 35, 97
Yule Marble, 24, 99
Z
Zinc, 74, 75, 80, 82, 83, 85, 86, 89
Zirkel, Mt., 19