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

Geologic units in Jackson county, Colorado

[Additional scientific data in this geographic area]

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

Granitic rocks of 1700-m.y. age group (Proterozoic | Paleoproterozoic) at surface, covers 6 % 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

Volcanic rocks in northwestern Colorado (Phanerozoic | Cenozoic | Tertiary) at surface, covers 3 % of this area

Mainly of intermediate compositions

Lithology: intermediate volcanic r

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

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

Upper Tertiary intrusive rocks (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area

Intermediate to felsic compositions

Lithology: plutonic rock (phanerit

Older glacial drift (Phanerozoic | Cenozoic | Quaternary) at surface, covers 1 % of this area

Lithology: glacial drift

Metasedimentary and metavolcanic rocks (Proterozoic | Paleoproterozoic ) at surface, covers 0.2 % 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

Modern alluvium (Phanerozoic | Cenozoic | Quaternary) at surface, covers 3 % of this area

Includes Piney Creek Alluvium and younger deposits

Lithology: alluvium

Mafic rocks of 1700-m.y. age group (Proterozoic | Paleoproterozoic) at surface, covers 0.3 % of this area

Gabbro and mafic diorite and monzonite

Lithology: gabbro; diorite; monzonite

Coalmont Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 35 % of this area

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

Lithology: sandstone; conglomerate; shale; coal

Granitic rocks of 1400-m.y. age group (Proterozoic | Mesoproterozoic) at surface, covers 3 % 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

Felsic and hornblendic gneisses, either separate or interlayered (Proterozoic | Paleoproterozoic) at surface, covers 9 % 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

Eolian deposits (Phanerozoic | Cenozoic | Quaternary) at surface, covers 1 % of this area

Includes dune sand and silt and Peoria Loess

Lithology: dune sand; silt; loess

North Park Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 4 % of this area

Sandstone, siltstone, and conglomerate; in North Park and Laramie basin

Lithology: sandstone; siltstone; conglomerate

White River Fm or Group (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.7 % 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

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 2 % of this area

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

Lithology: landslide; talus; colluvium

Chugwater Fm (Phanerozoic | Mesozoic | Triassic) at surface, covers 0.8 % of this area

Red sandstone, siltstone, shale, and local limestone and gypsum

Lithology: sandstone; mudstone; limestone; evaporite

Mesozoic rocks (Lower Phanerozoic | Mesozoic | Cretaceous-Triassic) at surface, covers 0.6 % of this area

Mainly Lower Cretaceous, Jurassic, and Triassic Fms

Lithology: clastic

Middle Tertiary intrusive rocks (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.7 % of this area

Intermediate to felsic compositions

Lithology: plutonic rock (phanerit

Dakota Sandstone or Group (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area

Lithology: sandstone

Dakota and Morrison Fms (Phanerozoic | Mesozoic | Jurassic Cretaceous) at surface, covers < 0.1 % of this area

Lithology: sandstone; mudstone; 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

Ash-flow tuff of main volcanic sequence (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.4 % of this area

Includes many named units

Lithology: ash-flow tuff

Triassic and Permian rocks (Phanerozoic | Paleozoic Mesozoic | Permian Triassic) at surface, covers 0.5 % 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

Gravels and alluviums (Phanerozoic | Cenozoic | Quaternary) at surface, covers 6 % of this area

Includes Broadway and Louviers Alluviums

Lithology: gravel; alluvium

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

Pierre Shale, undivided (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 6 % of this area

Lithology: shale

Dakota, Morrison, and Sundance Fms (Phanerozoic | Mesozoic | Jurassic Cretaceous) at surface, covers 2 % of this area

Lithology: sandstone; mudstone

Glacial drift (Phanerozoic | Cenozoic | Quaternary) at surface, covers 7 % of this area

Includes some unclassified glacial deposits

Lithology: glacial drift

Colorado Group (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 3 % of this area

Consists of Niobrara Formation (Kn) and either Benton Shale or Carlile, Greenhorn, and Graneros Fms (Kcg)

Lithology: shale; limestone

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

GRANITIC ROCKS OF 1,700-Ma AGE GROUP.

Lithology: granitoid