Part 9

Fault. A break in the rocks in which there has been displacement of the two sides relative to each other.

Fault block range. A mountain range bounded on two or more sides by faults.

Feldspar. A group of light-colored aluminum silicate minerals that are major constituents of igneous rocks. They contain potassium, sodium, and calcium in differing proportions.

Fold. A bend in rock layers.

Foraminiferida. One-celled marine animals with microscopic, perforated, many-chambered calcium carbonate shells, often called forams.

Fossil. The remains or traces of an animal or plant which has been preserved in the rock.

Fusulinid. One-celled marine animals (forams) with shells which look like a grain of wheat in shape and size, frequently abundant in Colorado Pennsylvanian rocks.

Galena. A heavy gray metallic mineral (PbS), often cubic in form, that is the most important ore of lead.

Gangue. Nonvaluable minerals occurring in veins with ore minerals.

Glaciation. Alteration of the earth’s surface by erosion and deposition by glacier ice.

Glacier. A body of ice originating on land by recrystallization of snow, and showing evidence of movement by flowing.

Gneiss. A coarse-grained metamorphic rock usually banded with streaks of darker, finer-grained rock.

Granite. An intrusive igneous rock consisting essentially of sodium or potassium feldspar and quartz, often speckled with dark-colored minerals.

Graptolite. Extinct marine organisms without known close living relatives, with small black sawblade-like chitinous hard parts preserved as fossils.

Hematite. A steel gray or metallic grayish black or reddish gray mineral (Fe₂O₃) that is an important ore of iron.

Hogback. A sharp-crested ridge formed by a resistant layer of steeply dipping rock.

Huebnerite. A heavy reddish brown mineral (MnWO₄) that is a major ore of tungsten.

Igneous rocks. Rocks formed by solidification from a molten state, either at the surface (extrusive) or below the surface (intrusive).

Intrusive rocks. Igneous rocks formed when molten rock material solidifies without reaching the surface.

Joint. A fracture in the rock, along which no discernible movement has taken place.

Kerogen. Solid bituminous material in oil shales.

Laccolith. A lens-shaped mass of igneous rock intruded into layered rocks.

Lava. Fluid or molten rock such as that which issues from a volcano.

Lode. A rock mass, often a vein, containing valuable minerals.

Massif. A mountainous mass that has relatively uniform geologic characteristics and which may embrace a number of peaks.

Mesa. A flat-topped mountain bounded on at least one side by a steep cliff.

Metamorphic rock. Rock formed by alteration of pre-existing rock, especially by great temperatures and pressures.

Mollusk. Any one of the large group of invertebrate animals which includes the snails, clams, octopuses, squids, and their extinct relatives.

Molybdenite. A soft bluish gray, metallic mineral (MoS₂) that is a major ore of molybdenum.

Monocline. A steplike fold in otherwise horizontal or gently dipping rock layers.

Moraine. An accumulation of unsorted rock material built up by the action of glacier ice.

Native gold. Gold occurring in nature uncombined with other elements.

Peneplain. A land surface worn down by erosion to a nearly flat or broadly undulating plain.

Petzite. A heavy black or steel gray metallic telluride ore of gold and silver (Ag₃AuTe₂).

Placer. A sand or gravel deposit containing particles or nuggets of gold or other heavy valuable minerals.

Plateau. An elevated, comparatively flat surface of land, usually larger than a mesa, sometimes composed of many mesas, and often dissected by deep stream valleys.

Porphyry. An igneous rock, usually intrusive, which contains conspicuous large crystals in a fine-grained matrix.

Pyrite. A brass-yellow metallic mineral (FeS₂) that is an important source of sulfur. It is commonly known as fool’s gold.

Reef. A moundlike limestone structure built in the sea by sedentary organisms such as corals.

Rhyolite. A light-colored volcanic rock with quartz and feldspar as the principal constituents.

Schist. A metamorphic rock characterized by parallel orientation of flat-grained minerals like mica.

Sedimentary rocks. Rocks formed of fragments of other rock transported by wind or water, or formed by precipitation from solution.

Sphalerite. An amber-yellow to black mineral (ZnS) that is an important ore of zinc.

Stalactite. A cylindrical or conical deposit of calcite hanging from the roof of a cavern, formed by evaporation of water droplets containing calcium carbonate.

Stalagmite. Columns or ridges of calcite rising from the floor of a cavern, formed by water containing calcium carbonate dripping from a stalactite.

Stock. A mass of igneous intrusive rock that covers less than 40 square miles, has steep sides, and extends to an unknown depth.

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 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

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