USGS Home
Contact USGS
Search USGS

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

Geologic units in Douglas county, Colorado

[Additional scientific data in this geographic area]

Wall Mountain Tuff (Phanerozoic | Cenozoic | Tertiary) at surface, covers 1 % of this area

Early ash-flow tuff of Sawatch Range provenance

Lithology: ash-flow tuff

Pierre Shale--Upper unit (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.2 % of this area

Lithology: shale

Colorado Group (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.5 % of this area

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

Lithology: shale; limestone

Pierre Shale, undivided (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.9 % of this area

Lithology: shale

Gravels and alluviums (Phanerozoic | Cenozoic | Quaternary) at surface, covers 3 % of this area

Includes Broadway and Louviers Alluviums

Lithology: gravel; alluvium

Lykins Fm and Lyons Sandstone (Phanerozoic | Paleozoic Mesozoic | Permian Triassic) at surface, covers 0.2 % of this area

Lithology: sandstone; mudstone; limestone

Pierre Shale--Middle unit (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.1 % 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

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

Fountain Fm (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian Permian) at surface, covers 1 % of this area

Arkosic sandstone and conglomerate

Lithology: sandstone; conglomerate

Lykins Lyons and Fountain Fms (Phanerozoic | Paleozoic Mesozoic | Carboniferous Pennsylvanian Permian(?) Triassic) at surface, covers 0.5 % of this area

Red siltstone, sandstone, and conglomerate

Lithology: siltstone; sandstone; conglomerate

Pierre Shale--Lower unit (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.2 % of this area

Sharon Springs Member (organic-rich shale and numerous bentonite beds) in lower part

Lithology: shale; bentonite

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

Includes Piney Creek Alluvium and younger deposits

Lithology: alluvium

Upper part of Dawson Arkose (Phanerozoic | Cenozoic | Tertiary) at surface, covers 44 % of this area

Arkosic sandstone, conglomerate, and shale. Includes Green Mountain Conglomerate south of Golden

Lithology: sandstone; conglomerate; shale

Granitic rocks of 1700-m.y. age group (Proterozoic | Paleoproterozoic) at surface, covers 0.2 % 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

Biotitic gneiss, schist, and migmatite (Proterozoic | Paleoproterozoic) at surface, covers 3 % 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

Older gravels and alluviums (Phanerozoic | Cenozoic | Quaternary) at surface, covers 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

Laramie Fm and Fox Hills Sandstone (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.5 % of this area

Lithology: sandstone; mudstone; coal

Rocks of Pikes Peak Batholith (1000-m.y. age group) (Proterozoic | Mesoproterozoic) at surface, covers 27 % of this area

Includes Pikes Peak, Mount Rosa, Windy Point, and Redskin Granites and unnamed rocks

Lithology: granite; granodiorite; quartz monzonite

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 0.4 % of this area

Lithology: sandstone; mudstone

Leadville Limestone, Williams Canyon Limestone , Manitou Limestone, and Sawatch Quartzite (Phanerozoic | Paleozoic | Cambrian Ordovician(?) Silurian(?) Devonian(?) Carboniferous) at surface, covers 0.4 % of this area

Lithology: limestone; quartzite

Denver Fm or lower part of Dawson Arkose (Phanerozoic | Mesozoic Cenozoic | Cretaceous Tertiary) at surface, covers 2 % of this area

Arkosic sandstone, shale, mudstone, conglomerate, and local coal beds

Lithology: sandstone; shale; mudstone; conglomerate; coal

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

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