USGS - science for a changing world

Mineral Resources On-Line Spatial Data

Mineral Resources > Online Spatial Data > Geology > by state > Colorado Geology

Geologic units in Colorado (state in United States)

[Additional scientific data in this geographic area]

Mancos Shale--Frontier Sandstone and Mowry Shale Members (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area
Frontier Sandstone and Mowry Shale Members and intervening shale zone
Lithology: sandstone; shale
Niobrara Fm (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 3 % of this area
Calcareous shale and limestone
Lithology: shale; limestone
Granitic rocks of 1700-m.y. age group (Proterozoic | Paleoproterozoic) at surface, covers 2 % of this area
Includes Boulder Creek -M.Y. AGE GROUP (AGE 1650-1730 M.Y.)--Includes Boulder Creek, Cross Creek, Denny Creek, Kroenke, Browns Pass, Powderhorn, Pitts Meadow, Bakers Bridge, and Tenmile Granites, Quartz Monzonites, or Granodiorites;
Lithology: granite; granodiorite; quartz monzonite
Leadville Limestone, Gilman Sandstone, Dyer Dolomite, and Parting Fm (Phanerozoic | Paleozoic | Ordovician Silurian(?) Devonian) at surface, covers 0.1 % of this area
Parting Fm: quartzite and shale.
Lithology: limestone; sandstone; dolostone (dolomite); shale; quartzite
Dakota Sandstone and Burro Canyon Fm (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 3 % of this area
Sandstone, shale, and conglomerate. In northwest and west-central: Lower Cretaceous. In southwest: Lower and Upper Cretaceous.
Lithology: sandstone; shale; conglomerate
Middle Tertiary intrusive rocks (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.7 % of this area
Intermediate to felsic compositions
Lithology: plutonic rock (phanerit
Older gravels and alluviums (Phanerozoic | Cenozoic | Quaternary) at surface, covers 3 % of this area
Includes Slocum, Verdos, Rocky Flats, and Nussbaum Alluviums in east, and Florida, Bridgetimber, and Bayfield Gravels in southwest
Lithology: gravel; alluvium
Landslide deposits (Phanerozoic | Cenozoic | Quaternary) at surface, covers 1 % of this area
Locally includes talus, rock-glacier, and thick colluvial deposits
Lithology: landslide; talus; colluvium
Dakota, Purgatoire, Morrison, Ralston Creek, and Entrada Fms in southeast. Dakota, Morrison, and Entrada Fms in central mountains. Dakota, Burro Canyon, Morrison, Wanakah, and Entrada Fms in Gunnison River area. Dakota, Morriso (Phanerozoic | Mesozoic | Jurassic Cretaceous) at surface, covers 0.2 % of this area
Lithology: sandstone; mudstone; limestone
Loess (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers < 0.1 % of this area
eolian silts
Lithology: silt
Gravels and alluviums (Phanerozoic | Cenozoic | Quaternary) at surface, covers 3 % of this area
Includes Broadway and Louviers Alluviums
Lithology: gravel; alluvium
Pre-ash-flow andesitic lavas, breccias, tuffs, and conglomerates (Phanerozoic | Cenozoic | Tertiary) at surface, covers 3 % of this area
Includes several named units
Lithology: andesite; tuff; volcanic breccia (agglomerate)
Denver Fm or lower part of Dawson Arkose (Phanerozoic | Mesozoic Cenozoic | Cretaceous Tertiary) at surface, covers 1.0 % of this area
Arkosic sandstone, shale, mudstone, conglomerate, and local coal beds
Lithology: sandstone; shale; mudstone; conglomerate; coal
Mesaverde Group or Fm--Upper part (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.6 % of this area
In Moffat and Rio Blanco Counties, sandstone, shale, and coal beds above Sego Sandstone. Along Grand Hogback south of Colorado River, sandstone and shale above coal-bearing sequence
Lithology: sandstone; shale; coal
Cutler Fm (Phanerozoic | Paleozoic | Permian) at surface, covers 0.3 % of this area
Arkosic sandstone, siltstone, and conglomerate
Lithology: sandstone; siltstone; conglomerate
Uncompahgre Fm (Proterozoic | Paleoproterozoic Mesoproterozoic) at surface, covers < 0.1 % of this area
Quartzite, slate, and phyllite
Lithology: quartzite; slate; phyllite
Weber Sandstone and Maroon Fm (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian Permian) at surface, covers 0.2 % of this area
Lithology: sandstone; siltstone; conglomerate
Morrison, Entrada, and Chinle Fms (Phanerozoic | Mesozoic | Triassic Jurassic) at surface, covers < 0.1 % of this area
Along southern Grand Hogback, Chinle is represented only by basal Gartra Sandstone Member
Lithology: mudstone; sandstone
Granitic rocks of 1400- and 1700-m.y. age groups, undivided, or, in Taylor River region, rocks with characteristics of Xg but U-Th-Pb zircon ages of Yg (Proterozoic | Paleoproterozoic Mesoproterozoic) at surface, covers 0.3 % of this area
Granitic rocks of 1400- and 1700-m.y. age groups, undivided, or, in Taylor River region, rocks with characteristics of Xg but U-Th-Pb zircon ages of Yg
Lithology: granitoid
Modern alluvium (Phanerozoic | Cenozoic | Quaternary) at surface, covers 3 % of this area
Includes Piney Creek Alluvium and younger deposits
Lithology: alluvium
Morrison Fm and Entrada Sandstone (Phanerozoic | Mesozoic | Jurassic) at surface, covers < 0.1 % of this area
Lithology: mudstone; sandstone
Mancos Shale (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 4 % of this area
Intertongues complexly with units overlying Mesaverde Group or Formation; lower part consists of a calcareous Niobrara equivalent and Frontier Sandstone and Mowry Shale Members; in areas where the Frontier and Mowry Members (Kmfm), or these and the Dakota Sandstone (Kfd) are distinguished, map unit (Km) consists of shale above Frontier Member
Lithology: shale; sandstone
Mafic rocks of 1700-m.y. age group (Proterozoic | Paleoproterozoic) at surface, covers < 0.1 % of this area
Gabbro and mafic diorite and monzonite
Lithology: gabbro; diorite; monzonite
Jurassic (1) sedimentary rocks in southeastern Utah (Middle to Late Jurassic) at surface, covers < 0.1 % of this area
Lithology: sandstone; mudstone; limestone; evaporite
Tertiary (2) sedimentary rocks in Uinta Mountains-Uinta Basin region (Eocene) at surface, covers < 0.1 % of this area
Lithology: shale; limestone; oil shale; fine-grained mixed clastic; tuff
Morrison, Ralston Creek, and Entrada (or Exeter) Fms (Phanerozoic | Mesozoic | Jurassic) at surface, covers 0.4 % of this area
Lithology: mudstone; sandstone
Mississippian (1) carbonate rocks in Uinta Mountains-Uinta Basin region (Mississippian) at surface, covers < 0.1 % of this area
Lithology: limestone
Dakota and Morrison Fms (Phanerozoic | Mesozoic | Jurassic Cretaceous) at surface, covers < 0.1 % of this area
Lithology: sandstone; mudstone; shale
Chinle And State Bridge Fms (Phanerozoic | Paleozoic Mesozoic | Permian Triassic) at surface, covers < 0.1 % of this area
Red siltstone and sandstone
Lithology: siltstone; sandstone
Animas Fm (Phanerozoic | Mesozoic Cenozoic | Cretaceous Tertiary) at surface, covers 0.3 % of this area
Arkosic sandstone, shale, and conglomerate; contains abundant volcanic materials; Upper Cretaceous volcaniclastic McDermott Member at base
Lithology: sandstone; shale; conglomerate; mixed clastic/volcanic
Triassic and Jurassic sedimentary rocks in southeastern Utah (Early Jurassic) at surface, covers < 0.1 % of this area
Lithology: sandstone; mudstone; limestone
Pennsylvanian and Permian sedimentary rocks in Uinta Mountains-Uinta Basin region (Pennsylvanian to Permian) at surface, covers < 0.1 % of this area
Lithology: arenite
Frontier Sandstone and Mowry Shale Members of Mancos Shale, and Dakota Sandstone (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area
Locally includes, at base, Burro Canyon Fm (shale and sandstone) or, in western Moffat County, Cedar Mountain Fm (conglomerate and shale)
Lithology: sandstone; shale; conglomerate
Glacial deposits (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers < 0.1 % of this area
GLACIAL DEPOSITS--Till and outwash of sand, gravel, and boulders.
Lithology: glacial drift
Mafic intrusive rocks (Proterozoic | Paleoproterozoic ) at surface, covers < 0.1 % of this area
MAFIC INTRUSIVE ROCKS. Sierra Madre--Gabbro of Elkhorn Mountain; age 1,800 Ma. Medicine Bow Mountains--Mullen Creek 5 and Lake Owens 7 Mafic Complexes; older than 1,700 Ma.
Lithology: gabbroid
Ash-flow tuff of main volcanic sequence (Phanerozoic | Cenozoic | Tertiary) at surface, covers 2 % of this area
Includes many named units
Lithology: ash-flow tuff
Leadville, Gilman, Dyer, Parting, and Sawatch Fms in west-central and south-central. Leadville Limestone, Ouray Limestone, Elbert Fm, and Ignacio Quartzite in far southwest (Phanerozoic | Paleozoic | Cambrian Ordovician(?) Silurian(?) Devonian(?) Carboniferous) at surface, covers < 0.1 % of this area
Elbert Fm: shale and sandstone.
Lithology: limestone; dolostone (dolomite); quartzite; sandstone; shale
Fox Hills Sandstone (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.5 % of this area
Lithology: sandstone
Fort Union Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.2 % of this area
Shale, sandstone, and local coal beds
Lithology: shale; sandstone; coal
Eagle Valley Fm - evaporitic facies (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian) at surface, covers 0.3 % of this area
Gypsum, siltstone, and shale; salt present in deep borings. Intertongues with Minturn and Lower Maroon Fms. Diapiric structure in many places
Lithology: siltstone; shale; evaporite
Eocene prevolcanic sedimentary rocks (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
South-central: Arkosic sand and bouldery gravel of Echo Park Alluvium. Southwest: includes Telluride Conglomerate and Blanco Basin Fm (arkosic mudstone, sandstone, and conglomerate)
Lithology: sandstone; conglomerate; mudstone
Chinle Fm (Phanerozoic | Mesozoic | Triassic) at surface, covers < 0.1 % of this area
Red siltstone, sandstone, and limestone-pellet conglomerate
Lithology: siltstone; sandstone; conglomerate
Browns Park Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 1 % of this area
Sandstone and siltstone; west of Park Range
Lithology: sandstone; siltstone
Wasatch Formation (SW) (Phanerozoic | Cenozoic | Tertiary | Paleocene Eocene) at surface, covers < 0.1 % of this area
WASATCH FORMATION Main body--Drab sandstone, drab to variegated claystone and siltstone; locally derived conglomerate around basin margins. Lower part is Paleocene.
Lithology: sandstone; fine-grained mixed clastic; conglomerate
Basalt flows and associated tuff, breccia, and conglomerate of late-volcanic bimodal suite (Phanerozoic | Cenozoic | Tertiary) at surface, covers 1 % of this area
Includes basalts of Hinsdale Fm in San Juan Mountains - Servilleta Fm in San Luis Valley and many other occurrences
Lithology: basalt; tuff; volcanic breccia (agglomerate); conglomerate
Mesaverde Fm, undivided (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.5 % of this area
In northwest and west-central: Major coal beds in lower part; Rollins Sandstone Member at base in Delta, Gunnison, and Pitkin Counties. In southwest: sandstone and shale.
Lithology: sandstone; shale; coal
One or more Ordovician fms (Phanerozoic | Paleozoic | Ordovician) at surface, covers < 0.1 % of this area
Fremont Limestone, Harding Sandstone, and Manitou Limestone
Lithology: limestone; sandstone
Glacial drift (Phanerozoic | Cenozoic | Quaternary) at surface, covers 2 % of this area
Includes some unclassified glacial deposits
Lithology: glacial drift
Glen Canyon Group and Chinle Fm (Phanerozoic | Mesozoic | Triassic Jurassic) at surface, covers 0.2 % of this area
In southwest, Glen Canyon Group consists of Navajo Sandstone, Kayenta Fm (red siltstone, shale, and sandstone) and Wingate Sandstone; Chinle is red siltstone
Lithology: sandstone; siltstone; shale
Pierre Shale--Upper unit (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 2 % of this area
Lithology: shale
lower part of Green River Fm and Wasatch Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Shale and sandstone
Lithology: shale; sandstone
Entrada Sandstone (Phanerozoic | Mesozoic | Jurassic) at surface, covers < 0.1 % of this area
Entrada Sandstone, Middle Jurassic; Callovian
Lithology: sandstone
Bouldery gravel on old erosion surfaces in Front Range and Never Summer Mountains (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Lithology: gravel
Morrison, Wanakah, and Entrada Fms (Phanerozoic | Mesozoic | Jurassic) at surface, covers 0.4 % of this area
Lithology: mudstone; sandstone; limestone
Intra-ash flow andesitic lavas (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.5 % of this area
Lithology: andesite
Greenhorn Limestone and Graneros Shale (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers < 0.1 % of this area
Greenhorn FM- thin bedded gray, chalky limestone and calcareous shale. Graneros Shale- fissile, noncalcareous, gray shale locally contains sandstone and siltstone beds.
Lithology: limestone; shale; sandstone; siltstone
Tertiary (1) sedimentary rocks in Uinta Mountains-Unita Basin region (Early to Middle Eocene) at surface, covers < 0.1 % of this area
Lithology: fine-grained mixed clastic; limestone; coal
Morrison Fm (Phanerozoic | Mesozoic | Jurassic) at surface, covers < 0.1 % of this area
Variegated claystone, mudstone, sandstone, and local beds of limestone
Lithology: mudstone; sandstone; limestone
Denver and Arapahoe Fms (Phanerozoic | Mesozoic Cenozoic | Cretaceous Tertiary) at surface, covers 0.2 % of this area
Sandstone, mudstone, claystone, and conglomerate; Denver is characterized by andesitic materials
Lithology: sandstone; mudstone; conglomerate
Cliff House Sandstone (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.3 % of this area
Lithology: sandstone
Dakota Sandstone and Purgatoire Fm (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 3 % of this area
Sandstone and shale
Lithology: sandstone; shale
Younger Precambrian metamorphic rocks in Uinta Mountains-Uinta Basin region (Proterozoic Y) at surface, covers < 0.1 % of this area
Lithology: arenite; shale; siltstone; mudstone; limestone; conglomerate
White River Fm or Group (Phanerozoic | Cenozoic | Tertiary) at surface, covers 2 % of this area
East: Ashy claystone and sandstone. Includes Castle Rock Conglomerate in region southeast of Denver. Northwest: Ashy claystone in North Park
Lithology: sandstone; claystone; conglomerate
Morrison Formation and upper San Rafael Group (Phanerozoic | Mesozoic | Jurassic) at surface, covers < 0.1 % of this area
Morrison Formation and upper San Rafael Group
Lithology: fine-grained mixed clastic; sedimentary rock; limestone
Morrison Formation (Phanerozoic | Mesozoic | Jurassic) at surface, covers < 0.1 % of this area
Morrison Formation; Upper Jurassic nonmarine rocks present only in northern one-third of state
Lithology: fine-grained mixed clastic; limestone
Volcanic rocks in northwestern Colorado (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.2 % of this area
Mainly of intermediate compositions
Lithology: intermediate volcanic r
Dakota Group and Morrison And Ralston Creek Fms at mountain front between Boulder and Colorado Springs. Dakota, Purgatoire, Morrison, and Ralston Creek Fms in Canon City area (Phanerozoic | Mesozoic | Jurassic Cretaceous) at surface, covers < 0.1 % of this area
Lithology: sandstone; mudstone
Biotitic gneiss, schist, and migmatite (Proterozoic | Paleoproterozoic) at surface, covers 2 % of this area
Locally contains minor hornblende gneiss, calc-silicate rock, quartzite, and marble. Derived principally from sedimentary rocks
Lithology: biotite gneiss; schist; migmatite; quartzite; marble
Mesozoic rocks (Lower Phanerozoic | Mesozoic | Cretaceous-Triassic) at surface, covers < 0.1 % of this area
Mainly Lower Cretaceous, Jurassic, and Triassic Fms
Lithology: clastic
Dry Union Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.2 % of this area
Siltstone, sandstone, and conglomerate. Includes Wagontongue Fm (Miocene) in South Park
Lithology: siltstone; sandstone; conglomerate; tuff
Rhyolitic intrusive rocks and flows of late-volcanic bimodal suite (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Lithology: rhyolite
Dune Sand (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers < 0.1 % of this area
unconsolidated dune sand
Lithology: sand
Laramide intrusive rocks (Phanerozoic | Mesozoic Cenozoic | Cretaceous Tertiary) at surface, covers 0.3 % of this area
Mainly intermediate to felsic compositions; some mafic
Lithology: granitoid
Cretaceous (3) sedimentary rocks in Uinta Mountains-Uinta Basin region (Late Cretaceous) at surface, covers < 0.1 % of this area
Lithology: sandstone; shale; coal
Bridger Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.2 % of this area
Claystone and mudstone; in Sand Wash basin
Lithology: mudstone; claystone
Oligocene sedimentary rocks (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.2 % of this area
Northwest: includes Duchesne River Fm (sandstone and shale; includes some rocks of Eocene age) and Bishop Conglomerate near Utah border. South-central: includes Florissant Lake Beds (tuffaceous shale and tuff) and Antero Fm (lime
Lithology: sandstone; shale; conglomerate
Dakota, Burro Canyon, Morrison, and Wanakah Fms (Phanerozoic | Mesozoic | Jurassic Cretaceous) at surface, covers < 0.1 % of this area
Lithology: sandstone; mudstone; limestone
Basalt flows and intrusive igneous rocks (Phanerozoic | Cenozoic | Tertiary | Miocene) at surface, covers < 0.1 % of this area
BASALT FLOWS AND INTRUSIVE IGNEOUS ROCKS (AGE ABOUT 11 Ma).
Lithology: basalt
Older glacial drift (Phanerozoic | Cenozoic | Quaternary) at surface, covers 0.1 % of this area
Lithology: glacial drift
Minturn and Belden Fms (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian) at surface, covers 0.3 % of this area
Lithology: sandstone; shale; limestone; conglomerate
Uinta Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 1 % of this area
Sandstone and siltstone; in Piceance basin. Formerly Evacuation Creek Member of Green River Fm
Lithology: sandstone; siltstone
Alluvium and Colluvium (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers < 0.1 % of this area
ALLUVIUM AND COLLUVIUM--Clay, silt, sand, and gravel in flood plains, fans, terraces, and slopes.
Lithology: alluvium; colluvium
Wasatch Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.9 % of this area
Claystone, shale, and sandstone
Lithology: claystone; shale; sandstone
Fountain Fm (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian Permian) at surface, covers 0.1 % of this area
Arkosic sandstone and conglomerate
Lithology: sandstone; conglomerate
Laramie Fm and Fox Hills Sandstone (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.1 % of this area
Lithology: sandstone; mudstone; coal
basalt and andesite flows, Neogene (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Basalt and andesite flows; Neogene. Includes flows interbedded with Santa Fe and Gila Groups
Lithology: basalt; andesite
Quaternary landslides (Quaternary) at surface, covers < 0.1 % of this area
Lithology: landslide
Laramie Fm (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 2 % of this area
Shale, claystone, sandstone, and major coal beds
Lithology: shale; claystone; sandstone; coal
Ingleside Fm and Fountain Fm (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian Permian) at surface, covers < 0.1 % of this area
Ingleside Fm: Limestone and calcareous sandstone. Fountain Fm: arkosic sandstone and conglomerate
Lithology: sandstone; limestone; conglomerate
Eolian deposits (Phanerozoic | Cenozoic | Quaternary) at surface, covers 11 % of this area
Includes dune sand and silt and Peoria Loess
Lithology: dune sand; silt; loess
Pierre Shale--Middle unit (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.7 % of this area
In Boulder-Fort Collins area, contains Richard, Larimer, Rocky Ridge, Terry, and Hygiene Sandstone Members; elsewhere shale between zones of Baculites reesidei and B. scotti
Lithology: shale; sandstone
Carlile Shale, Greenhorn Limestone, and Graneros Shale (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 2 % of this area
Lithology: shale; limestone
Dakota Sandstone or Group (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.2 % of this area
Lithology: sandstone
Upper Tertiary intrusive rocks (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Intermediate to felsic compositions
Lithology: plutonic rock (phanerit
Wasatch Fm (including Fort Union equivalent at base) and Ohio Creek Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 1 % of this area
Claystone, mudstone, sandstone, and conglomerate
Lithology: mudstone; sandstone; shale; conglomerate
Jelm and Chugwater Formations, Forelle Limestone, and Satanka Shale (Phanerozoic | Paleozoic Mesozoic | Permian Triassic-Early) at surface, covers < 0.1 % of this area
JELM AND CHUGWATER FORMATIONS, FORELLE LIMESTONE, AND SATANKA SHALE. CHUGWATER FORMATION OR GROUP--Red shale and siltstone containing thin gypsum partings near base. Group includes Popo Agie Formation (red shale and red, yellow, and purple siltstone; lenses of lime-pellet conglomerate), Crow Mountain Sandstone (red and gray, thick bedded), Alcova Limestone, and Red Peak Formation (red siltstone and shale). Chugwater Formation includes as members all the units listed above. Includes overlying Jelm Formation in Shirley and Seminoe Mountains and at northern end of Laramie Basin. JELM FORMATION--Red sandstone. FORELLE LIMESTONE--Thin-bedded limestone. Locally is a member of the Goose Egg Formation. SATANKA SHALE--Red shale.
Lithology: fine-grained mixed clastic; medium-grained mixed clastic; mixed clastic/carbonate; evaporite
Maroon Fm (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian Permian) at surface, covers 0.5 % of this area
Arkosic sandstone, siltstone, conglomerate, and local limestone
Lithology: sandstone; siltstone; conglomerate; limestone
Ancient alluvium (Phanerozoic | Cenozoic | Tertiary Quaternary) at surface, covers < 0.1 % of this area
In isolated patches that may not all be of the same age
Lithology: alluvium
Basaltic flows in Denver Fm near Golden (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Lithology: basalt
Sangre de Cristo Fm (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian Permian) at surface, covers 0.3 % of this area
Arkosic conglomerate, sandstone, and siltstone
Lithology: conglomerate; sandstone; siltstone
Manitou Limestone and Sawatch Quartzite in Southern Front Range and Wet Mountains. One or more Ordovician Fms (Fremont Limestone, Harding Sandstone, and Manitou Dolomite), Dotsero Fm, Peerless Fm, and Sawatch Quartzite in west-ce (Phanerozoic | Paleozoic | Cambrian Ordovician) at surface, covers 0.1 % of this area
Dotsero Fm: Dolomite, in White River plateau only. Peerless Fm: sandstone and dolomite.
Lithology: limestone; dolostone (dolomite); quartzite; sandstone
Chugwater Fm (Phanerozoic | Mesozoic | Triassic) at surface, covers < 0.1 % of this area
Red sandstone, siltstone, shale, and local limestone and gypsum
Lithology: sandstone; mudstone; limestone; evaporite
Casper Fm and Lower part of Fountain Fm (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian Permian) at surface, covers < 0.1 % of this area
Casper Fm: sandstone
Lithology: sandstone; conglomerate
Unclassified surficial deposits and underlying Alamosa Fm in San Luis Valley (Phanerozoic | Cenozoic | Tertiary Quaternary) at surface, covers 2 % of this area
Alamosa Fm: gravel, sand, silt
Lithology: alluvium
Granitic rocks of 1400-m.y. age group (Proterozoic | Mesoproterozoic) at surface, covers 2 % of this area
Includes Silver Plume, Sherman, Cripple Creek, St. Kevin, Vernal Mesa, Curecanti, Eolus, and Trimble Granites or Quartz Monzonites; also, San Isabel Granite of Boyer (1962) and unnamed granitic rocks
Lithology: granite; granodiorite; quartz monzonite
Cretaceous (2) sedimentary rocks in southeastern Utah (Late Cretaceous) at surface, covers < 0.1 % of this area
Lithology: shale; sandstone; limestone
Minturn Fm in west-central and south-central and other units (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian) at surface, covers 0.6 % of this area
Arkosic sandstone, conglomerate, shale, and limestone. Includes Madera Fm and Sharpsdale Fm of Chronic (1958) in Sangre de Cristo Range and Gothic Fm of Langenheim (1952) in Elk Mountains. Other units of Middle Pennsylvanian age.
Lithology: sandstone; conglomerate; shale; limestone
Permian (2) sedimentary rocks in Uinta Mountains-Uinta Basin region (Permian) at surface, covers < 0.1 % of this area
Lithology: sandstone; carbonate; fine-grained mixed clastic; phosphorite
Felsic and hornblendic gneisses, either separate or interlayered (Proterozoic | Paleoproterozoic) at surface, covers 2 % of this area
Includes metabasalt, metatuff, and interbedded metagraywacke; locally contains interlayered biotite gneiss. Derived principally from volcanic rocks
Lithology: felsic gneiss; mafic gneiss; meta-basalt; meta-graywacke
Quartzite, conglomerate, and interlayered mica schist (Proterozoic | Paleoproterozoic) at surface, covers < 0.1 % of this area
Quartzite, conglomerate, and interlayered mica schist
Lithology: quartzite; conglomerate; mica schist
Ogallala Formation (Phanerozoic | Cenozoic | Tertiary | Miocene) at surface, covers < 0.1 % of this area
massive to cross-bedded, generally arkosic sand, silt and gravel, locally cemented with calcium carbonate; also contains limestone, volcanic ash, diatomaceous marl, opaline sandstone and bentonitic clay
Lithology: arkose; limestone; volcanic ash; carbonate; sandstone; claystone
Hermosa Fm (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian) at surface, covers < 0.1 % of this area
Arkosic sandstone, conglomerate, shale, and limestone; gypsum and salt in Paradox Member present in salt anticlines near Utah border
Lithology: sandstone; conglomerate; shale; limestone; evaporite
Pierre Shale--Lower unit (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.6 % of this area
Sharon Springs Member (organic-rich shale and numerous bentonite beds) in lower part
Lithology: shale; bentonite
middle and upper Jurassic rocks, unidivided (Phanerozoic | Mesozoic | Jurassic) at surface, covers < 0.1 % of this area
Jurassic rocks, Middle and Upper, undivided
Lithology: clastic; sedimentary rock
Alluvium (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers < 0.1 % of this area
unconsolidated sand, silt, clay, and gravel
Lithology: gravel; sand; silt; clay or mud
Ogallala Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 8 % of this area
Loose to well-cemented sand and gravel
Lithology: sandstone; conglomerate
South Park Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Arkosic sandstone and shale, volcaniclastic conglomerate, and andesite flows and breccia
Lithology: sandstone; shale; conglomerate; andesite; volcanic breccia (agglo
Mancos Shale (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area
Mancos Shale; divided into Upper and Lower parts by Gallup Sandstone
Lithology: shale; fine-grained mixed clastic
Green River Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Marlstone, sandstone, and oil shale
Lithology: mudstone; shale; sandstone
Dakota Sandstone (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area
Dakota Sandstone; includes Oak Canyon, Cubero, and Paguate Tongues plus Clay Mesa Tongue of Mancos Shale; Cenomanian
Lithology: medium-grained mixed clastic
Pierre Shale (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers < 0.1 % of this area
thin bedded gray to brownish gray shale; contains concretions, selenite crystals, thin beds of bentonite and locally chalky beds.
Lithology: shale
Tertiary (5) sedimentary rocks in Uinta Mountains-Uinta Basin region (Miocene) at surface, covers < 0.1 % of this area
Lithology: sandstone; conglomerate; volcanic rock (aphanitic); limestone; chert
Basaltic intrusive rocks related to basalt flows (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
In dikes and plugs
Lithology: basalt
silicic pyroclastic rocks (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Lower Oligocene silicic pyroclastic rocks (ash-flow tuffs); includes Hell's Mesa, Kneeling Nun, lower part of Bell Top Formation, Caballo Blanco, Datil Well, Leyba Well, Rock House Canyon, Blue Canyon, Sugarlump and Tadpole Ridge Tuffs, the tuffs of the Organ cauldron, Treasure Mountain Tuff (now known as Chiquito Peak Tuff), Bluff Creek Tuff, Oak Creek Tuff, tuff of Steins Mountain, tuff of Black Bill Canyon, tuff of Farr Ranch, Woodhaul Canyon, Gillespie and Box Canyon Tuffs, Cooney Tuff, and other volcanic and interbedded fluvial and pumiceous units; (31-36.5 Ma)
Lithology: pyroclastic; tuff; felsic volcanic rock; volcanic rock (aphanitic); mixed clastic/volcanic
Cliff House Sandstone (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area
Cliff House Sandstone; transgressive marine sandstone; Campanian
Lithology: sandstone; shale
Intra-ash flow quartz latitic lavas (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.2 % of this area
Lithology: quartz latite
Telluride conglomerate of Eocene prevolcanic sedimentary rocks (Te) and Cimarron Ridge Fm (Phanerozoic | Mesozoic Cenozoic | Cretaceous Tertiary) at surface, covers < 0.1 % of this area
In northwestern San Juan Mountains. Cimarron Ridge Fm: volcanic breccia and conglomerate.
Lithology: conglomerate; volcanic breccia (agglomer
Dolores Fm (Phanerozoic | Mesozoic | Triassic) at surface, covers 0.1 % of this area
Red siltstone, shale, sandstone, and limestone-pellet conglomerate
Lithology: siltstone; shale; sandstone; conglomerate
Mesaverde Formation (N) or Mesaverde Group (S) (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers < 0.1 % of this area
MESAVERDE FORMATION (north Wyoming)--Light-colored massive to thin-bedded sandstone, gray sandy shale, and coal beds. In Jackson Hole locally contains gold-bearing quartzite conglomerate. North of North Fork Powder River east of the Bighorn Mountains, consists solely of the Parkman Sandstone Member; MESAVERDE GROUP (SOUTH WYOMING). Includes Almond Formation, Ericson Sandstone, Rock Springs and Blair Formations in Rock Springs uplift; Almond Formation (white and brown soft sandstone, gray sandy shale, coal and carbonaceous shale), Pine Ridge Sandstone (light-gray sandstone and thin coal beds), and Allen Ridge (gray sandstone, shale, and thin coal beds) and Haystack Mountains (gray marine sandstone and shale) Formations in Rawlins uplift; Pine Ridge Sandstone (light-gray sandstone and thin coal beds) and Rock River Formation (soft sandstone and sandy shale) in Laramie Basin.
Lithology: sandstone; shale; coal; conglomerate
Lykins Lyons and Fountain Fms (Phanerozoic | Paleozoic Mesozoic | Carboniferous Pennsylvanian Permian(?) Triassic) at surface, covers < 0.1 % of this area
Red siltstone, sandstone, and conglomerate
Lithology: siltstone; sandstone; conglomerate
Intrusive rocks (Phanerozoic | Paleozoic | Cambrian) at surface, covers < 0.1 % of this area
Alkalic and mafic intrusive rocks in small plutons, and diabase dikes
Lithology: diabase
Wall Mountain Tuff (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Early ash-flow tuff of Sawatch Range provenance
Lithology: ash-flow tuff
Madison Limestone and Lodore Fm (Phanerozoic | Paleozoic | Cambrian Ordovician(?) Silurian(?) Devonian(?) Carboniferous) at surface, covers < 0.1 % of this area
Lithology: limestone; sandstone; shale; conglomerate
Dockum Group (Phanerozoic | Mesozoic | Triassic) at surface, covers < 0.1 % of this area
Red sandstone, siltstone, and local limestone
Lithology: sandstone; siltstone; limestone
Mesaverde Group (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area
Mesaverde Group includes the Gallup Sandstone, Crevasse Canyon Formation, Point Lookout Sandstone, Menefee Formation, and Cliff House Sandstone
Lithology: sandstone; fine-grained mixed clastic; conglomerate; coal
Kayenta Fm, Wingate Sandstone, and Chinle Fm (Phanerozoic | Mesozoic | Triassic) at surface, covers 0.4 % of this area
Kayenta Fm: red siltstone, shale, and sandstone. Chinle Fm: red siltstone and sandstone
Lithology: sandstone; siltstone; shale
Upper part of Dawson Arkose (Phanerozoic | Cenozoic | Tertiary) at surface, covers 1 % of this area
Arkosic sandstone, conglomerate, and shale. Includes Green Mountain Conglomerate south of Golden
Lithology: sandstone; conglomerate; shale
Green River Fm--Laney Member (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.2 % of this area
Claystone, oil shale, and sandstone; in Sand Wash basin
Lithology: claystone; oil shale; sandstone
Fort Union Formation (Phanerozoic | Cenozoic | Tertiary | Paleocene ) at surface, covers < 0.1 % of this area
FORT UNION FORMATION northwest, southwest, and central Wyoming--Brown to gray sandstone, gray to black shale, and thin coal beds; east Wyoming--Light-colored massive sandstone, drab shale, and thick coal beds.
Lithology: sandstone; shale; coal
Metasedimentary and metavolcanic rocks (Proterozoic | Paleoproterozoic ) at surface, covers < 0.1 % of this area
METASEDIMENTARY AND METAVOLCANIC ROCKS. Sierra Madre--Granite gneiss, felsic gneiss, amphibolite, and metavolcanic rocks. Medicine Bow Mountains--Granite gneiss, felsic gneiss, amphibolite, and hornblende gneiss. Laramie Mountains--Pelitic schist, marble, granite gneiss, layered amphibolite, and felsic gneiss. Black Hills--Pelitic schist; includes minor amounts of granite and amphibolite.
Lithology: metasedimentary rock; metavolcanic rock
Triassic and Permian rocks (Phanerozoic | Paleozoic Mesozoic | Permian Triassic) at surface, covers < 0.1 % of this area
Red siltstone, shale, and sandstone. Includes various combinations of Nugget, Jelm, Popo Agie, Chugwater, Red Peak, Forelle, Satanka, and Goose Egg Fms near Wyoming border
Lithology: siltstone; shale; sandstone
Older Precambrian metamorphic rocks in southeastern Utah (Precambrian) at surface, covers < 0.1 % of this area
Lithology: metamorphic rock; plutonic rock (phaneritic); mudstone
Sawatch Quartzite (Phanerozoic | Paleozoic | Cambrian) at surface, covers < 0.1 % of this area
Locally includes Peerless Fm
Lithology: quartzite; sandstone; dolostone (dolomite)
Morrison and Ralston Creek Fms (Phanerozoic | Mesozoic | Jurassic) at surface, covers < 0.1 % of this area
Ralston Creek Fm: Claystone, sandstone, limestone, and gypsum
Lithology: mudstone; sandstone; limestone; evaporite
Dakota Group (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area
Dakota Group of east-central and northeast New Mexico; in ascending order, Mesa Rica Sandstone, Pajarito Shale, and Romeroville Sandstone; includes the underlying Tucumcari Shale in Tucumcari area and Glencairn Formation in Union County. Encompasses both Upper and Lower Cretaceous rocks
Lithology: sandstone; medium-grained mixed clastic
Leadville Limestone, Williams Canyon Limestone , Manitou Limestone, and Sawatch Quartzite (Phanerozoic | Paleozoic | Cambrian Ordovician(?) Silurian(?) Devonian(?) Carboniferous) at surface, covers 0.2 % of this area
Lithology: limestone; quartzite
Cretaceous (1) sedimentary rocks in southeastern Utah (Cretaceous) at surface, covers < 0.1 % of this area
Lithology: sandstone; shale
Upper Miocene Rocks (Phanerozoic | Cenozoic | Tertiary | Miocene-Late) at surface, covers < 0.1 % of this area
UPPER MIOCENE ROCKS--Southwest Wyoming: South end of Wind River Range--Siliceous, arkosic, and locally radioactive sandstone, claystone, and conglomerate. Fission-track age about 27 Ma. Recent work suggests that part of these deposits may be of Eocene age. Pliocene and Miocene (as originally defined 2) South Pass Formation. Saratoga Valley--White to greenish-gray tuffaceous sandstone, siltstone, and claystone; locally conglomeratic. North Park Formation; Central Wyoming: Arkosic sandstone, conglomerate, and siltstone; some light-colored tuffaceous radioactive claystone and white cherty limestone. North of Sweetwater River in Granite Mountains--Light-colored tuffaceous radioactive claystone, siltstone, sandstone, and arkose. Moonstone Formation; East Wyoming: Light-colored tuffaceous claystone, sandstone, and conglomerate. Ogallala Formation in Denver Basin.
Lithology: sandstone; claystone; conglomerate; siltstone; limestone
Chinle, Moenkopi, and Park City Fms (Phanerozoic | Paleozoic Mesozoic | Permian Triassic) at surface, covers < 0.1 % of this area
Red and gray siltstone, shale, and sandstone
Lithology: siltstone; shale; sandstone
Morrison, Curtis, and Entrada Fms (Phanerozoic | Mesozoic | Jurassic) at surface, covers < 0.1 % of this area
In extreme southwestern Moffat County, includes thin wedge of Carmel Fm (red siltstone and sandstone) beneath Entrada
Lithology: mudstone; sandstone
Ogallala Group or Formation (Phanerozoic | Cenozoic | Tertiary | Miocene) at surface, covers < 0.1 % of this area
Silt, sand, sandstone, gravel and conglomerate. Predominantly interfingered fine- to coarse grained, poorly sorted, arkosic, fluvial deposits of light-gray, light-olive-gray, and grayish-green calcareous silt and sand, and locally poorly consolidated conglomerate, sandstone, and siltstone.
Lithology: mudstone; sandstone; volcanic ash
Parting, Fremont, and Harding Fms (Phanerozoic | Paleozoic | Ordovician Silurian(?) Devonian) at surface, covers < 0.1 % of this area
Lithology: quartzite; sandstone; limestone; shale
Santa Fe Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.4 % of this area
Siltstone, sandstone, and conglomerate
Lithology: siltstone; sandstone; conglomerate
Belden Fm (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian) at surface, covers 0.1 % of this area
Shale, limestone, and sandstone. Includes Kerber Fm in south-central
Lithology: shale; limestone; sandstone
Basalt flows (Phanerozoic | Cenozoic | Quaternary) at surface, covers < 0.1 % of this area
Lithology: basalt
Permian (1) sedimentary rocks in southeastern Utah (Pennsylvanian to Early Permian) at surface, covers < 0.1 % of this area
Lithology: sandstone; fine-grained mixed clastic; limestone
Williams Fork Fm (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.6 % of this area
Sandstone, shale, and major coal beds
Lithology: sandstone; shale; coal
Pierre Shale (Kp), Niobrara (Kn), and Carlile, Greenhorn, and Graneros (Kcg) Fms, undivided (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area
Lithology: shale; limestone
Coalmont Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.9 % of this area
Arkosic sandstone, conglomerate, and shale; coal in lower part; in North Park
Lithology: sandstone; conglomerate; shale; coal
Weber Sandstone (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian Permian) at surface, covers 0.1 % of this area
Lithology: sandstone
Lykins Fm and Lyons Sandstone (Phanerozoic | Paleozoic Mesozoic | Permian Triassic) at surface, covers < 0.1 % of this area
Lithology: sandstone; mudstone; limestone
Mesozoic and Paleozoic rocks (Phanerozoic | Paleozoic Mesozoic | Carboniferous Pennsylvanian) at surface, covers < 0.1 % of this area
Mainly as in Mesozoic unit (MZ) plus Permian and Pennsylvanian Fms
Lithology: clastic
Colorado Group (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.3 % of this area
Consists of Niobrara Formation (Kn) and either Benton Shale or Carlile, Greenhorn, and Graneros Fms (Kcg)
Lithology: shale; limestone
Quaternary alluvium and colluvium (Quaternary) at surface, covers < 0.1 % of this area
Lithology: alluvium; colluvium
Vermejo Fm and Trinidad Sandstone (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.1 % of this area
Shale, sandstone, and major coal beds; sandstone
Lithology: sandstone; shale; coal
Pierre Shale, undivided (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.9 % of this area
Lithology: shale
Dakota, Burro Canyon, Morrison, and Junction Creek Fms (Phanerozoic | Mesozoic | Jurassic Cretaceous) at surface, covers < 0.1 % of this area
Burro Canyon is locally absent
Lithology: sandstone; mudstone; shale
Lykins Fm (Phanerozoic | Paleozoic Mesozoic | Permian Triassic) at surface, covers < 0.1 % of this area
Red siltstone, shale, and limestone
Lithology: siltstone; shale; limestone
Carlile Shale (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers < 0.1 % of this area
chalky shale with bentonite and thick chalk beds, dark gray fissile shale containing septarian concretions, and fine-grained sandstone.
Lithology: shale; limestone; sandstone
Poison Canyon Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.5 % of this area
Arkosic conglomerate, sandstone, and shale
Lithology: sandstone; conglomerate; shale
Windy Gap Member of Middle Park Fm (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area
Andesitic breccia and conglomerate
Lithology: mixed clastic/volcanic
Morrison Fm, Summerville Fm, and Entrada Sandstone (Phanerozoic | Mesozoic | Jurassic) at surface, covers 1 % of this area
Summerville Fm: Shale and siltstone
Lithology: mudstone; sandstone
Uinta Mountain Group (Proterozoic | Mesoproterozoic) at surface, covers 0.3 % of this area
Quartzite, conglomerate, and shale
Lithology: quartzite; conglomerate; shale
Pictured Cliffs Sandstone and Lewis Shale (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.2 % of this area
Lithology: sandstone; shale
Raton Fm (Phanerozoic | Mesozoic Cenozoic | Cretaceous Tertiary) at surface, covers 0.4 % of this area
Arkosic sandstone, siltstone, and shale; contains major coal deposits in Raton Basin
Lithology: sandstone; mudstone; coal
Green River Fm--Tipton Tongue (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.1 % of this area
Claystone and oil shale; in Sand Wash basin. In extreme northwest includes rocks of Wilkins Peak Member
Lithology: claystone; oil shale
Cloverly, Morrison, and Sundance Formations (Phanerozoic | Mesozoic | Jurassic-Middle Jurassic-Late(?) Cretaceous-Early) at surface, covers < 0.1 % of this area
CLOVERLY, MORRISON, AND SUNDANCE (Js) FORMATIONS. CLOVERLY FORMATION--Rusty sandstone at top, underlain by brightly variegated bentonitic claystone; chert-pebble conglomerate locally at base. MORRISON FORMATION--Dully variegated claystone, nodular limestone, and gray silty sandstone. In southern Yellowstone and Jackson Hole areas the presence of Morrison is questionable. SUNDANCE FORMATION--Greenish-gray glauconitic sandstone and shale, underlain by red and gray nonglauconitic sandstone and shale.
Lithology: fine-grained mixed clastic; medium-grained mixed clastic; limestone; mixed clastic/volcanic; conglomerate
Sherman Granite (Proterozoic | Mesoproterozoic (1415-1435 Ma)) at surface, covers < 0.1 % of this area
SHERMAN GRANITE (AGE 1,415 TO 1,435 Ma)--In Medicine Bow and Laramie Mountains.
Lithology: granite
Rocks of Pikes Peak Batholith (1000-m.y. age group) (Proterozoic | Mesoproterozoic) at surface, covers 1 % of this area
Includes Pikes Peak, Mount Rosa, Windy Point, and Redskin Granites and unnamed rocks
Lithology: granite; granodiorite; quartz monzonite
Green River Formation: Luman Tongue (Phanerozoic | Cenozoic | Tertiary | Eocene) at surface, covers < 0.1 % of this area
GREEN RIVER FORMATION Luman Tongue--Oil shale, carbonaceous shale, and sandstone.
Lithology: fine-grained mixed clastic; oil shale
Alkalic and mafic rocks in small plutons, and diabase and gabbro dikes (Proterozoic | Mesoproterozoic) at surface, covers < 0.1 % of this area
Alkalic and mafic rocks in small plutons, and diabase and gabbro dikes
Lithology: granitoid; diabase; gabbro
Kirtland and Fruitland Formations (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area
Kirtland and Fruitland Formations; coal-bearing, coal primarily in the Fruitland; Campanian to Maastrichtian
Lithology: sandstone; mudstone; coal
Older Quaternary alluvial deposits (Quaternary) at surface, covers < 0.1 % of this area
Lithology: alluvium
Tertiary (4) sedimentary rocks in Uinta Mountains-Uinta Basin region (Oligocene) at surface, covers < 0.1 % of this area
Lithology: conglomerate
North Park Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.1 % of this area
Sandstone, siltstone, and conglomerate; in North Park and Laramie basin
Lithology: sandstone; siltstone; conglomerate
Leadville Limestone, Williams Canyon Limestone, and one or more of: Fremont Limestone, Harding Sandstone, and Manitou Limestone (Phanerozoic | Paleozoic | Ordovician Silurian(?) Devonian(?) Carboniferous Mississippia) at surface, covers < 0.1 % of this area
Lithology: limestone; sandstone
Cretaceous (2) sedimentary rocks in Uinta Mountains-Uinta Basin region (Late Cretaceous) at surface, covers < 0.1 % of this area
Lithology: shale; sandstone
Park City Fm (Phanerozoic | Paleozoic | Permian) at surface, covers < 0.1 % of this area
Calcareous siltstone and sandstone
Lithology: siltstone; sandstone
Cambrian quartzite in Uinta Mountains-Uinta Basin area (Early to Middle Cambrian) at surface, covers < 0.1 % of this area
Lithology: sandstone; shale; conglomerate
Arikaree Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Sandstone; contains abundant volcanically derived material
Lithology: sandstone; conglomerate; tuff
Dakota, Morrison, and Sundance Fms (Phanerozoic | Mesozoic | Jurassic Cretaceous) at surface, covers 0.1 % of this area
Lithology: sandstone; mudstone
Upper Permian rocks, undivided (Phanerozoic | Paleozoic | Permian) at surface, covers < 0.1 % of this area
Siltstone, dolomite, and sandstone; in southeast
Lithology: siltstone; dolostone (dolomite); sandstone
Iles Fm (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.4 % of this area
Sandstone and shale. Trout Creek Sandstone Member at top; coal beds in upper half
Lithology: sandstone; shale; coal
Jelm, Lykins, Lyons, and Satanka Fms (Phanerozoic | Paleozoic Mesozoic | Permian Triassic) at surface, covers < 0.1 % of this area
Red siltstone, shale, and sandstone
Lithology: mudstone; sandstone; limestone
Menefee Fm and Point Lookout Sandstone (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.2 % of this area
sandstone, shale, and coal; sandstone
Lithology: sandstone; shale; coal
Morrison Fm and Wanakah Fm (Junction Creek Sandstone Member at or near top; Pony Express Limestone Member at base) (Phanerozoic | Mesozoic | Jurassic) at surface, covers < 0.1 % of this area
Wanakah Fm: Sandstone, shale, limestone, and local gypsum
Lithology: mudstone; sandstone; limestone; evaporite
Los Pinos Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Volcaniclastic conglomerate interbedded with basalt flows of Hinsdale Fm (Tbb) on east flank of San Juan Mountains. Grades laterally into Santa Fe Fm of San Luis Valley
Lithology: mixed clastic/volcanic; basalt
Menefee Formation (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area
Menefee Formation; mudstone, shale, and sandstone; coal-bearing
Lithology: fine-grained mixed clastic; coal; limestone
Rico and Hermosa Fms (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian) at surface, covers 0.2 % of this area
Arkosic sandstone, conglomerate, shale, and limestone. Includes at base in some areas siltstone and shale of Molas Fm or Larsen Quartzite
Lithology: sandstone; conglomerate; shale; limestone; mudstone
Morrison Formation (Phanerozoic | Mesozoic | Jurassic-Late ) at surface, covers < 0.1 % of this area
CIMARRON- Varicolored fine-grained sandstone, limestone, dolomite, shale, and conglomerate 0 to 470 +/- feet thick.
Lithology: sandstone; limestone; dolostone (dolomite); shale; conglomerate
Green River Fm--Lower Part (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.6 % of this area
Shale, sandstone, marlstone, and limestone in Anvil Points, Garden Gulch, and Douglas Creek Members; in Piceance basin
Lithology: mudstone; shale; sandstone
Morrison, Curtis, Entrada, and Glen Canyon Fms (Phanerozoic | Mesozoic | Triassic Jurassic) at surface, covers < 0.1 % of this area
Curtis is absent along Grand Hogback
Lithology: mudstone; sandstone
Glen Canyon Sandstone (Phanerozoic | Mesozoic | Triassic Jurassic) at surface, covers < 0.1 % of this area
In northwest
Lithology: sandstone
Lodore Fm (Phanerozoic | Paleozoic | Cambrian) at surface, covers < 0.1 % of this area
Sandstone, shale, and conglomerate
Lithology: sandstone; shale; conglomerate
Cuchara Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.2 % of this area
Sandstone and shale
Lithology: sandstone; shale
Chinle Group (Phanerozoic | Mesozoic | Triassic) at surface, covers < 0.1 % of this area
Chinle Group; Upper Triassic; includes Moenkopi Formation (Middle Triassic) at base in many areas; in eastern part of state the following five formations are mapped:
Lithology: medium-grained mixed clastic; fine-grained mixed clastic; limestone; chert; evaporite
White River Formation (Phanerozoic | Cenozoic | Tertiary | Oligocene (31-35 Ma)) at surface, covers < 0.1 % of this area
WHITE RIVER FORMATION (AGE 31 TO 35 Ma)--White to pale-pink blocky tuffaceous claystone and lenticular arkosic conglomerate.
Lithology: fine-grained mixed clastic; medium-grained mixed clastic; mixed clastic/volcanic
Huerfano Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.1 % of this area
Shale and sandstone. Includes Farisita Conglomerate in northwestern Huerfano County
Lithology: shale; sandstone; conglomerate
Gravel, pediment, and fan deposits (Phanerozoic | Cenozoic | Quaternary | Pleistocene Holocene) at surface, covers < 0.1 % of this area
GRAVEL, PEDIMENT, AND FAN DEPOSITS--Mostly locally derived clasts. Includes some glacial deposits along east flank of Wind River Range. Locally includes some Tertiary gravels.
Lithology: unconsolidated deposit
Green River Fm--Parachute Creek Member (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.4 % of this area
Parachute Creek Member--Oil shale, marlstone, and siltstone; in Piceance basin
Lithology: mudstone; shale; oil shale
Wasatch Fm--Niland Tongue (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Mudstone, sandstone, and carbonaceous shale; in Sand Wash basin
Lithology: mudstone; sandstone; shale
Kirtland Shale and Fruitland Fm (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area
Shale, sandstone, and major coal beds
Lithology: shale; sandstone; coal
Williams Canyon Limestone, Manitou Limestone, and Sawatch Quartzite (Phanerozoic | Paleozoic | Cambrian Ordovician(?) Silurian(?) Devonian) at surface, covers < 0.1 % of this area
Lithology: limestone; quartzite
sedimentary units, Palogene (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Paleogene sedimentary units; includes Baca, Galisteo, El Rito, Blanco Basin, Love Ranch, Lobo, Sanders Canyon, Skunk Ranch, Timberlake, and Cub Mountain Formations
Lithology: medium-grained mixed clastic; tuff; limestone; sand; clay or mud
Chinle and Chugwater Fms (Phanerozoic | Mesozoic | Triassic) at surface, covers < 0.1 % of this area
Lithology: sandstone; mudstone; evaporite
Quaternary eolian deposits (Quaternary) at surface, covers < 0.1 % of this area
Lithology: eolian
landslide deposits and colluvium (Phanerozoic | Cenozoic | Quaternary) at surface, covers < 0.1 % of this area
Landslide deposits and colluvium
Lithology: landslide; colluvium
Pierre Shale (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers < 0.1 % of this area
Mostly medium to dark-gray, brownish-gray, and black, fissle clay shale. Locally grades to thin beds of calcareous, silty shale or claystone, marl, shaly sandstone, and sandy shale. Locally contains thin seams of gypsum and sparse selenite crystals. Approx. max thickness 1970 ft.
Lithology: shale; evaporite
Troublesome Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.2 % of this area
Sandstone and siltstone; in Middle Park
Lithology: sandstone; siltstone
Mount Garfield Fm and Sego Sandstone (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.1 % of this area
Sandstone and shale; major coal beds in lower part of Mount Garfield
Lithology: sandstone; shale; coal
piedmont alluvial deposits (Phanerozoic | Cenozoic | Quaternary) at surface, covers < 0.1 % of this area
Piedmont alluvial deposits: upper and middle Quaternary; includes deposits of higher gradient tributaries bordering major stream valleys, alluvial veneers of the piedmont slope, and alluvial fans
Lithology: alluvium
Jurassic (2) sedimentary rocks in southeastern Utah (Late Jurassic) at surface, covers < 0.1 % of this area
Lithology: shale; sandstone; conglomerate
Green River Fm--Luman Tongue (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Carbonaceous shale and marlstone; in Sand Wash basin
Lithology: shale; mudstone
Green River Formation: Tipton Shale Member or Tongue (Phanerozoic | Cenozoic | Tertiary | Eocene) at surface, covers < 0.1 % of this area
GREEN RIVER FORMATION Tipton Shale Member or Tongue--Oil shale and marlstone.
Lithology: oil shale; mixed clastic/carbonate
Hunter Canyon Fm (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.3 % of this area
Sandstone and shale
Lithology: sandstone; shale
Triassic (2) sedimentary rocks in southeastern Utah (Late Triassic) at surface, covers < 0.1 % of this area
Lithology: mudstone; sandstone; siltstone; conglomerate; limestone
Red Creek Quartzite (Archean) at surface, covers < 0.1 % of this area
Metaquartzite, amphibolite, and mica schist. Present only in small area at Utah border in Uinta Mountains
Lithology: quartzite; amphibolite; mica schist
Purgatoire Formation (Phanerozoic | Mesozoic | Cretaceous-Early ) at surface, covers < 0.1 % of this area
CIMARRON- Kiowa Shale Member: Gray to black fossiliferous shale with sandstone in the upper part. Thickness ranges from 0 to 50 +/- feet. Cheyenne Sandstone Member: Massive, white to buff, fine- to medium-grained sandstone, containing some conglomerate in the lower part, from 0 to 120 +/- feet thick.
Lithology: shale; sandstone; conglomerate
Granitic rocks (Proterozoic | Paleoproterozoic ) at surface, covers < 0.1 % of this area
GRANITIC ROCKS OF 1,700-Ma AGE GROUP.
Lithology: granitoid
White River Group (Phanerozoic | Cenozoic | Tertiary | Oligocene) at surface, covers < 0.1 % of this area
Clay, some claystone, silt and siltstone. Predominantly greenish gray and volcaniclastic. Other occurrences are greenish gray to white and bentonitic. Local channel sandstone at base. Aprox thickness 195 ft.
Lithology: clay or mud; claystone; silt; siltstone
Green River Formation: Laney Member (Phanerozoic | Cenozoic | Tertiary | Eocene) at surface, covers < 0.1 % of this area
GREEN RIVER FORMATION Laney Member (age probably about 45 Ma)--Oil shale and marlstone.
Lithology: oil shale; mixed clastic/carbonate
Eagle Valley Fm (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian) at surface, covers < 0.1 % of this area
Siltstone, shale, and local gypsum
Lithology: siltstone; shale; evaporite
Tertiary (3) sedimentary rocks in Uinta Mountains-Uinta Basin region (Middle Eocene to Early Oligocene) at surface, covers < 0.1 % of this area
Lithology: sandstone; mudstone; siltstone; pyroclastic
intrusive rocks (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Tertiary intrusive rocks; undifferentiated
Lithology: plutonic rock (phaneritic)
Nacimiento Formation (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Nacimiento Formation; Paleocene, San Juan Basin
Lithology: sandstone; shale; conglomerate
Pictured Cliffs Sandstone (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area
Pictured Cliffs Sandstone; prominent cliff-forming marine sandstone
Lithology: sandstone; mudstone
Wingate Sandstone and Chinle Fm (Phanerozoic | Mesozoic | Triassic) at surface, covers 0.2 % of this area
Lithology: sandstone; siltstone; conglomerate
Miocene Rocks (Phanerozoic | Cenozoic | Tertiary | Miocene) at surface, covers < 0.1 % of this area
MIOCENE ROCKS--Southwest Wyoming: Southern Rock Springs uplift--Pale-green to tan tuffaceous sandstone and claystone of Miocene(?) age. Conglomerate of uncertain correlation locally at base. Saratoga Valley and west and southwest to Colorado--White massive soft tuffaceous sandstone and lesser amounts of white marl; lower part conglomeratic. Underlies North Park Formation in Saratoga Valley. To the west and southwest is called Browns Park Formation. Rawlins area--White massive soft tuffaceous sandstone; Central Wyoming: White soft tuffaceous sandstone. Locally derived conglomerate in upper and lower parts of sequence; in places lower conglomeratic sequence may be of Oligocene age. In Granite Mountains K/Ar age of tuff in lower part of sandstone sequence about 17 Ma and fission-track age of lower conglomerate about 24 Ma.
Lithology: sandstone; conglomerate; claystone
Sego Sandstone, Buck Tongue of Mancos Shale, and Castlegate Sandstone (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area
Lithology: sandstone; shale
Dolores Fm and Cutler Fm (Phanerozoic | Paleozoic Mesozoic | Permian Triassic) at surface, covers < 0.1 % of this area
Red siltstone, sandstone, and conglomerate
Lithology: siltstone; sandstone; conglomerate
alluvium (Phanerozoic | Cenozoic | Quaternary) at surface, covers < 0.1 % of this area
Alluvium; upper and middle Quaternary
Lithology: alluvium
Ogallala Formation (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Ogallala Formation, alluvial and eolian deposits, and petrocalcic soils of the southern High Plains; Lower Pliocene to middle Miocene (locally includes unit Qoa)
Lithology: alluvium; eolian; carbonate
Raton Formation (Phanerozoic | Mesozoic Cenozoic | Cretaceous Tertiary) at surface, covers < 0.1 % of this area
Raton Formation; in Raton Basin; unit contains conformable K/T boundary
Lithology: sandstone; mudstone; coal; conglomerate
San Jose Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.3 % of this area
Siltstone, shale, and sandstone
Lithology: siltstone; shale; sandstone
Animas Formation (Phanerozoic | Mesozoic Cenozoic | Cretaceous Tertiary) at surface, covers < 0.1 % of this area
Animas Formation; in northeast San Juan Basin
Lithology: clay or mud; tuff; clastic
Lewis Shale (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area
Lewis Shale; marine shale and mudstone
Lithology: shale; fine-grained mixed clastic; limestone
Ash-flow tuff of late-volcanic bimodal suite (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Lithology: ash-flow tuff
Evaporitic facies of Minturn And Belden Fms in South Park and southward (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian) at surface, covers < 0.1 % of this area
Gypsum, siltstone, and shale
Lithology: siltstone; shale; evaporite
Morgan Fm and Round Valley Limestone (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian) at surface, covers 0.2 % of this area
Morgan Fm: limestone, sandstone, and shale. In far northwest.
Lithology: limestone; sandstone; shale
Lewis Shale (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.3 % of this area
Lithology: shale
Green River Formation: Wilkins Peak Member (Phanerozoic | Cenozoic | Tertiary | Eocene) at surface, covers < 0.1 % of this area
GREEN RIVER FORMATION Wilkins Peak Member (age about 49 Ma)--Green, brown, and gray tuffaceous sandstone, shale, and marlstone; contains evaporites in subsurface sections.
Lithology: fine-grained mixed clastic; mixed clastic/carbonate; mixed clastic/volcanic; evaporite
Point Lookout Sandstone (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area
Point Lookout Sandstone; regressive marine sandstone in McKinley and Sandoval Counties. The lower, Hosta Tongue, of Point Lookout is transgressive and is separated from main body by the Satan Tongue of Mancos Shale; Santonian - Campanian
Lithology: sandstone; arkose
State Bridge Fm (Phanerozoic | Paleozoic Mesozoic | Permian Triassic) at surface, covers 0.1 % of this area
Red and orange siltstone and sandstone
Lithology: siltstone; sandstone
Morrison Fm and Junction Creek Sandstone (Phanerozoic | Mesozoic | Jurassic) at surface, covers < 0.1 % of this area
In Gunnison River area east of wedgeout of all units of Wanakah Fm (Jmw) except the Junction Creek Member
Lithology: mudstone; sandstone
Jurassic (1) sedimentary rocks in Uinta Mountains-Uinta Basin region (Middle to Late Jurassic) at surface, covers < 0.1 % of this area
Lithology: sandstone; mudstone; limestone; evaporite
Dakota Sandstone (Phanerozoic | Mesozoic | Cretaceous-Early ) at surface, covers < 0.1 % of this area
CIMARRON- Buff to light-brown, fine- to medium-grained, thin bedded to massive sandstone with interbedded shales.
Lithology: sandstone; shale
Mancos Shale--Juana Lopez Member (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area
Calcareous sandstone; a thin but persistent unit distinguished only locally
Lithology: sandstone; shale
Moenkopi Fm and Cutler Fm (Phanerozoic | Paleozoic Mesozoic | Permian Triassic) at surface, covers < 0.1 % of this area
Red siltstone and sandstone
Lithology: siltstone; sandstone
Older eolian deposits (Phanerozoic | Cenozoic | Quaternary) at surface, covers < 0.1 % of this area
Includes Loveland Loess
Lithology: dune sand; silt; loess
Wasatch Formation (SW) (Phanerozoic | Cenozoic | Tertiary | Eocene) at surface, covers < 0.1 % of this area
WASATCH FORMATION Cathedral Bluffs Tongue--Variegated claystone and lenticular sandstone; conglomeratic near south margin of Wind River Range.
Lithology: fine-grained mixed clastic; medium-grained mixed clastic
Morrison Fm and Curtis Fm (Phanerozoic | Mesozoic | Jurassic) at surface, covers < 0.1 % of this area
Morrison Fm: Variegated claystone, mudstone, sandstone, and local beds of limestone. Curtis Fm: glauconitic sandstone and limestone
Lithology: mudstone; sandstone; limestone
Chugwater and Goose Egg Formations (Phanerozoic | Paleozoic Mesozoic | Permian Triassic-Early(?) Triassic-Middle(?) Triassic-Late) at surface, covers < 0.1 % of this area
CHUGWATER AND GOOSE EGG FORMATIONS (north Wyoming). CHUGWATER FORMATION--Red siltstone and shale. Alcova Limestone Member in upper middle part in north Wyoming. Thin gypsum partings near base in north and northeast Wyoming. GOOSE EGG FORMATION--Red sandstone and siltstone, white gypsum, halite, and purple to white dolomite and limestone; CHUGWATER FORMATION OR GROUP (south Wyoming)--Red shale and siltstone containing thin gypsum partings near base. Group includes Popo Agie Formation (red shale and red, yellow, and purple siltstone; lenses of lime-pellet conglomerate), Crow Mountain Sandstone (red and gray, thick bedded), Alcova Limestone, and Red Peak Formation (red siltstone and shale). Chugwater Formation includes as members all the units listed above. Includes overlying Jelm Formation in Shirley and Seminoe Mountains and at northern end of Laramie Basin. JELM FORMATION--Red sandstone. GOOSE EGG FORMATION--Red sandstone and siltstone, white gypsum, halite, and purple to white dolomite and limestone.
Lithology: siltstone; sandstone; shale; conglomerate; evaporite; dolostone (dolomite); limestone
Mesaverde Group or Fm--Lower part (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area
Sandstone, shale, and major coal beds
Lithology: sandstone; shale; coal
San Jose Formation (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
San Jose Formation; Eocene, San Juan Basin
Lithology: medium-grained mixed clastic
Forelle Limestone and Satanka Shale (Phanerozoic | Paleozoic | Permian) at surface, covers < 0.1 % of this area
FORELLE LIMESTONE AND SATANKA SHALE. FORELLE LIMESTONE--Thin-bedded limestone. Locally is a member of the Goose Egg Formation. SATANKA SHALE--Red shale .
Lithology: limestone; shale
Wasatch Fm--Cathedral Bluffs Tongue (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.5 % of this area
Claystone, mudstone, and sandstone; in Sand Wash basin
Lithology: claystone; mudstone; sandstone
Cretaceous (1) sedimentary rocks in Uinta Mountains-Uinta Basin region (Cretaceous) at surface, covers < 0.1 % of this area
Lithology: sandstone; shale
Jurassic (2) sedimentary rocks in Uinta Mountains-Uinta Basin region (Late Jurassic) at surface, covers < 0.1 % of this area
Lithology: shale; sandstone; limestone; conglomerate
Lewis Shale (Phanerozoic | Mesozoic | Cretaceous-Late) at surface, covers < 0.1 % of this area
LEWIS SHALE (AGE ABOUT 68 Ma)--Gray marine shale containing many gray and brown lenticular concretion-rich sandstone beds.
Lithology: shale; sandstone
Dune Sand (Phanerozoic | Cenozoic | Quaternary | Pleistocene) at surface, covers < 0.1 % of this area
CIMARRON- Fine- to medium-grained sand 0 to 40 feet thick. TEXAS- Fine to coarse windblown sand. Maximum thickness about 30 feet. BEAVER- Fine to coarse, round to sub-round, windblown sand consisting mostly of quartz grains. 0-50 feet thick
Lithology: sand
volcanic rocks, lower Oligocene and Eocene (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Lower Oligocene and Eocene volcanic rocks, undifferentiated; dominantly intermediate composition, with interbedded volcaniclastic rocks; (31-44 Ma)
Lithology: volcanic rock (aphanitic); intermediate volcanic rock; mixed clastic/volcanic
Nacimiento Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Shale and sandstone
Lithology: shale; sandstone
Alluvium (Phanerozoic | Cenozoic | Quaternary | Holocene) at surface, covers < 0.1 % of this area
CIMARRON- Clay, silt, sand, and gravel 0 to 100 feet thick. TEXAS- Sand, silt, clay, and gravel located in valleys of principal streams. Thickness not known but may exceed 100 feet in North Canadian River valley and may be 50 to 100 feet in lower parts of valleys of Coldwater and Palo Duro Creeks BEAVER - Sand, gravel, silt, and clay in discontinuous lenses along courses of larger streams. 0-50 feet thick
Lithology: alluvium
Moenkopi Fm (Phanerozoic | Mesozoic | Triassic) at surface, covers < 0.1 % of this area
Red siltstone, mudstone, sandstone, and local gypsum
Lithology: mudstone; sandstone; evaporite
Wasatch Formation (SW) (Phanerozoic | Cenozoic | Tertiary | Eocene) at surface, covers < 0.1 % of this area
WASATCH FORMATION Niland Tongue--Brown sandstone, carbonaceous shale, and coal.
Lithology: sandstone; shale; coal
Madison Limestone (Phanerozoic | Paleozoic | Carboniferous Mississippian) at surface, covers < 0.1 % of this area
Upper part includes equivalents of Upper Mississippian Doughnut and Humbug Fms (shale, limestone, and sandstone)
Lithology: limestone; shale; sandstone
Ogallala Formation (Phanerozoic | Cenozoic | Tertiary | Pliocene) at surface, covers < 0.1 % of this area
CIMARRON- Generally semiconsolidated clay, silt, sand, gravel, and caliche 0 to 400 feet thick. BEAVER- Interbedded sand, siltstone, clay, gravel lenses, and thin limestone. Caliche common near surface but occurrence is not limited to the surface. Caliche accounts for most of the white color in the Ogallala. Other colors generally light tan or buff but locally may be pastel shades of almost any color. The Laverne and Rexroad Formations of Pliocene age and the Meade Group and Odee (of local usage) and other formations of Pleistocene age occur locally and are included with the Ogallala Formation, 0-700 feet thick. WOODWARD- Gravel, sand, silt, clay, caliche, and limestone, locally cemented with calcium carbonate. Generally light-tan to gray to white. Thickness ranges up to 400 feet and probably averages 150 feet. CLINTON- Gray to light-brown, fine- to medium-grained sand with some, clay, silt, gravel, volcanic ash, and caliche beds; locally cemented by calcium carbonate. Thickness ranges from 0 to about 320 feet. The formation thins eastward.
Lithology: sand; siltstone; clay or mud; gravel; limestone; volcanic ash
Casper and Fountain Formations (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian-Middle Pennsylvanian-Late Permian) at surface, covers < 0.1 % of this area
CASPER AND FOUNTAIN FORMATIONS. CASPER FORMATION--Gray, tan, and red thick-bedded sandstone underlain by interbedded sandstone and pink and gray limestone. May include some Devonian(?) sandstone along east flank of Laramie Mountains. FOUNTAIN FORMATION--Arkose and red sandstone.
Lithology: sandstone; limestone
Poison Canyon Formation (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area
Poison Canyon Formation; Paleocene, Raton Basin
Lithology: sandstone
Graneros Shale and Greenhorn Formation (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area
Graneros Shale and Greenhorn Formation; limited to northeastern area; lower Turonian and Cenomanian
Lithology: shale; limestone
Chugwater Formation (N, NE), or Chugwater Formation or Group (S) (Phanerozoic | Mesozoic | Triassic-Early Triassic-Middle(?) Triassic-Late) at surface, covers < 0.1 % of this area
CHUGWATER FORMATION (north, northeast Wyoming)--Red siltstone and shale. Alcova Limestone Member in upper middle part in north Wyoming. Thin gypsum partings near base in north and northeast Wyoming. [None mapped in the NE]; CHUGWATER FORMATION OR GROUP (south Wyomingt)--Red shale and siltstone containing thin gypsum partings near base. Group includes Popo Agie Formation (red shale and red, yellow, and purple siltstone; lenses of lime-pellet conglomerate), Crow Mountain Sandstone (red and gray, thick bedded), Alcova Limestone, and Red Peak Formation (red siltstone and shale). Chugwater Formation includes as members all the units listed above. Includes overlying Jelm Formation in Shirley and Seminoe Mountains and at northern end of Laramie Basin. JELM FORMATION--Red sandstone.
Lithology: siltstone; shale; sandstone; limestone; conglomerate
Morrison Fm and Sundance Fm (Phanerozoic | Mesozoic | Jurassic) at surface, covers < 0.1 % of this area
Sundance Fm: Sandstone, shale, claystone, and limestone
Lithology: mudstone; sandstone; limestone
Pennsylvanian sedimentary rocks in Uinta Mountains-Uinta Basin region (Pennsylvanian) at surface, covers < 0.1 % of this area
Lithology: dolostone (dolomite); sandstone
Dockum Group (Phanerozoic | Mesozoic | Triassic-Late ) at surface, covers < 0.1 % of this area
CIMARRON- Upper shale unit: Varicolored siltstone or claystone, conglomerate, fine-grained sandstone, and limestone. Lower sandstone unit: Varicolored, fine- to coarse-grained sandstone with some clay and interbedded shale.
Lithology: shale; siltstone; conglomerate; sandstone; limestone

Accessibility FOIA Privacy Policies and Notices

Take Pride in America logo USA.gov logo U.S. Department of the Interior | U.S. Geological Survey
URL: http://tin.er.usgs.gov/geology/state/fips-unit.php?state=CO
Page Contact Information: pschweitzer@usgs.gov
Page Last modified: 11:25 on 07-Jan-2014