USGS Home
Contact USGS
Search USGS

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

Geologic units in Summit county, Colorado

[Additional scientific data in this geographic area]

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

Lithology: sandstone; mudstone; shale

Middle Tertiary intrusive rocks (Phanerozoic | Cenozoic | Tertiary) at surface, covers 3 % of this area

Intermediate to felsic compositions

Lithology: plutonic rock (phanerit

Dakota Sandstone or Group (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.6 % of this area

Lithology: sandstone

Maroon Fm (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian Permian) at surface, covers 4 % of this area

Arkosic sandstone, siltstone, conglomerate, and local limestone

Lithology: sandstone; siltstone; conglomerate; limestone

Glacial drift (Phanerozoic | Cenozoic | Quaternary) at surface, covers 14 % of this area

Includes some unclassified glacial deposits

Lithology: glacial drift

Colorado Group (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 4 % of this area

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

Lithology: shale; limestone

Gravels and alluviums (Phanerozoic | Cenozoic | Quaternary) at surface, covers 1 % of this area

Includes Broadway and Louviers Alluviums

Lithology: gravel; alluvium

Pierre Shale, undivided (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 12 % of this area

Lithology: shale

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

Red siltstone, sandstone, and limestone-pellet conglomerate

Lithology: siltstone; sandstone; conglomerate

Morrison Fm (Phanerozoic | Mesozoic | Jurassic) at surface, covers 2 % of this area

Variegated claystone, mudstone, sandstone, and local beds of limestone

Lithology: mudstone; sandstone; limestone

Older glacial drift (Phanerozoic | Cenozoic | Quaternary) at surface, covers 2 % of this area

Lithology: glacial drift

Modern alluvium (Phanerozoic | Cenozoic | Quaternary) at surface, covers 0.6 % of this area

Includes Piney Creek Alluvium and younger deposits

Lithology: alluvium

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

Sandstone and siltstone; in Middle Park

Lithology: sandstone; siltstone

Granitic rocks of 1700-m.y. age group (Proterozoic | Paleoproterozoic) at surface, covers 7 % 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 0.3 % of this area

Mainly of intermediate compositions

Lithology: intermediate volcanic r

Laramide intrusive rocks (Phanerozoic | Mesozoic Cenozoic | Cretaceous Tertiary) at surface, covers 6 % of this area

Mainly intermediate to felsic compositions; some mafic

Lithology: granitoid

Biotitic gneiss, schist, and migmatite (Proterozoic | Paleoproterozoic) at surface, covers 23 % 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

Dry Union Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.5 % of this area

Siltstone, sandstone, and conglomerate. Includes Wagontongue Fm (Miocene) in South Park

Lithology: siltstone; sandstone; conglomerate; tuff

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 % of this area

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

Lithology: landslide; talus; colluvium

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

Felsic and hornblendic gneisses, either separate or interlayered (Proterozoic | Paleoproterozoic) at surface, covers 8 % 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

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

Minturn Fm in west-central and south-central and other units (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian) at surface, covers 4 % 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