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

Geologic units in Routt county, Colorado

[Additional scientific data in this geographic area]

Older gravels and alluviums (Phanerozoic | Cenozoic | Quaternary) at surface, covers 0.5 % of this area

Includes Slocum, Verdos, Rocky Flats, and Nussbaum Alluviums in east, and Florida, Bridgetimber, and Bayfield Gravels in southwest

Lithology: gravel; alluvium

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 < 0.1 % of this area

Lithology: sandstone; mudstone; limestone

Landslide deposits (Phanerozoic | Cenozoic | Quaternary) at surface, covers 1.0 % of this area

Locally includes talus, rock-glacier, and thick colluvial deposits

Lithology: landslide; talus; colluvium

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

Fort Union Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.2 % of this area

Shale, sandstone, and local coal beds

Lithology: shale; sandstone; coal

Browns Park Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 18 % of this area

Sandstone and siltstone; west of Park Range

Lithology: sandstone; siltstone

Mesozoic rocks (Lower Phanerozoic | Mesozoic | Cretaceous-Triassic) at surface, covers 0.2 % of this area

Mainly Lower Cretaceous, Jurassic, and Triassic Fms

Lithology: clastic

Wasatch Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 1 % of this area

Claystone, shale, and sandstone

Lithology: claystone; shale; 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

Minturn Fm in west-central and south-central and other units (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian) at surface, covers 0.7 % 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

Felsic and hornblendic gneisses, either separate or interlayered (Proterozoic | Paleoproterozoic) at surface, covers 6 % 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

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

Morrison, Curtis, and Entrada Fms (Phanerozoic | Mesozoic | Jurassic) at surface, covers 0.7 % of this area

In extreme southwestern Moffat County, includes thin wedge of Carmel Fm (red siltstone and sandstone) beneath Entrada

Lithology: mudstone; sandstone

Williams Fork Fm (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 7 % of this area

Sandstone, shale, and major coal beds

Lithology: sandstone; shale; coal

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 0.9 % of this area

Lithology: glacial drift

Coalmont Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area

Arkosic sandstone, conglomerate, and shale; coal in lower part; in North Park

Lithology: sandstone; conglomerate; shale; coal

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

Mafic rocks of 1700-m.y. age group (Proterozoic | Paleoproterozoic) at surface, covers 2 % of this area

Gabbro and mafic diorite and monzonite

Lithology: gabbro; diorite; monzonite

Modern alluvium (Phanerozoic | Cenozoic | Quaternary) at surface, covers 2 % of this area

Includes Piney Creek Alluvium and younger deposits

Lithology: alluvium

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

Granitic rocks of 1700-m.y. age group (Proterozoic | Paleoproterozoic) at surface, covers 9 % 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

Upper Tertiary intrusive rocks (Phanerozoic | Cenozoic | Tertiary) at surface, covers 1 % of this area

Intermediate to felsic compositions

Lithology: plutonic rock (phanerit

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

Biotitic gneiss, schist, and migmatite (Proterozoic | Paleoproterozoic) at surface, covers 1 % 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

Volcanic rocks in northwestern Colorado (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.6 % of this area

Mainly of intermediate compositions

Lithology: intermediate volcanic r

Mesaverde Fm, undivided (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.2 % 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

Laramie Fm (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 5 % of this area

Shale, claystone, sandstone, and major coal beds

Lithology: shale; claystone; sandstone; coal

Basalt flows (Phanerozoic | Cenozoic | Quaternary) at surface, covers 0.1 % of this area

Lithology: basalt

Sawatch Quartzite (Phanerozoic | Paleozoic | Cambrian) at surface, covers < 0.1 % of this area

Locally includes Peerless Fm

Lithology: quartzite; sandstone; dolostone (dolomite)

Granitic rocks (Proterozoic | Paleoproterozoic ) at surface, covers < 0.1 % of this area

GRANITIC ROCKS OF 1,700-Ma AGE GROUP.

Lithology: granitoid

Glacial drift (Phanerozoic | Cenozoic | Quaternary) at surface, covers 3 % of this area

Includes some unclassified glacial deposits

Lithology: glacial drift

Rhyolitic intrusive rocks and flows of late-volcanic bimodal suite (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area

Lithology: rhyolite

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

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

Chinle and Chugwater Fms (Phanerozoic | Mesozoic | Triassic) at surface, covers 0.4 % of this area

Lithology: sandstone; mudstone; evaporite

Gravels and alluviums (Phanerozoic | Cenozoic | Quaternary) at surface, covers 0.9 % of this area

Includes Broadway and Louviers Alluviums

Lithology: gravel; alluvium

Mancos Shale (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 16 % of this area

In northwest and west-central: Intertongues complexly with units of overlying Mesaverde Group or Fm; lower part consists of a calcareous Niobrara equivalent and Frontier Sandstone and Mowry Shale Members; in areas where the Frontie

Lithology: shale; sandstone

Dakota, Morrison, and Sundance Fms (Phanerozoic | Mesozoic | Jurassic Cretaceous) at surface, covers 0.7 % of this area

Lithology: sandstone; mudstone

Lewis Shale (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 10 % of this area

Lithology: shale

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

Chinle Fm (Phanerozoic | Mesozoic | Triassic) at surface, covers < 0.1 % of this area

Red siltstone, sandstone, and limestone-pellet conglomerate

Lithology: siltstone; sandstone; conglomerate

Iles Fm (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 6 % of this area

Sandstone and shale. Trout Creek Sandstone Member at top; coal beds in upper half

Lithology: sandstone; shale; coal

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

Triassic and Permian rocks (Phanerozoic | Paleozoic Mesozoic | Permian Triassic) at surface, covers 0.4 % 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

Basalt flows and associated tuff, breccia, and conglomerate of late-volcanic bimodal suite (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.9 % 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

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 0.4 % of this area

Elbert Fm: shale and sandstone.

Lithology: limestone; dolostone (dolomite); quartzite; sandstone; shale

Chinle And State Bridge Fms (Phanerozoic | Paleozoic Mesozoic | Permian Triassic) at surface, covers 0.4 % of this area

Red siltstone and sandstone

Lithology: siltstone; sandstone

Middle Tertiary intrusive rocks (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.2 % of this area

Intermediate to felsic compositions

Lithology: plutonic rock (phanerit

Weber Sandstone and Maroon Fm (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian Permian) at surface, covers < 0.1 % of this area

Lithology: sandstone; siltstone; conglomerate

Maroon Fm (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian Permian) at surface, covers 0.2 % of this area

Arkosic sandstone, siltstone, conglomerate, and local limestone

Lithology: sandstone; siltstone; conglomerate; limestone

Dakota Sandstone or Group (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 2 % of this area

Lithology: sandstone