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

Geologic units in Grand county, Colorado

[Additional scientific data in this geographic area]

Basalt flows and associated tuff, breccia, and conglomerate of late-volcanic bimodal suite (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.8 % 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

Ash-flow tuff of main volcanic sequence (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.2 % of this area

Includes many named units

Lithology: ash-flow tuff

Dakota and Morrison Fms (Phanerozoic | Mesozoic | Jurassic Cretaceous) at surface, covers 0.4 % of this area

Lithology: sandstone; mudstone; shale

Maroon Fm (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian Permian) at surface, covers < 0.1 % 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 0.9 % of this area

Lithology: sandstone

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

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

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

Intermediate to felsic compositions

Lithology: plutonic rock (phanerit

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

Glacial drift (Phanerozoic | Cenozoic | Quaternary) at surface, covers 5 % of this area

Includes some unclassified glacial deposits

Lithology: glacial drift

Windy Gap Member of Middle Park Fm (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 1 % of this area

Andesitic breccia and conglomerate

Lithology: mixed clastic/volcanic

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

Lithology: rhyolite

Morrison Fm and Entrada Sandstone (Phanerozoic | Mesozoic | Jurassic) at surface, covers < 0.1 % of this area

Lithology: mudstone; sandstone

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

Dakota, Morrison, and Sundance Fms (Phanerozoic | Mesozoic | Jurassic Cretaceous) at surface, covers 0.5 % of this area

Lithology: sandstone; mudstone

Morrison Fm (Phanerozoic | Mesozoic | Jurassic) at surface, covers 0.4 % 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

Pierre Shale, undivided (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 8 % of this area

Lithology: shale

Chinle and Chugwater Fms (Phanerozoic | Mesozoic | Triassic) at surface, covers 0.2 % of this area

Lithology: sandstone; mudstone; evaporite

Gravels and alluviums (Phanerozoic | Cenozoic | Quaternary) at surface, covers 2 % of this area

Includes Broadway and Louviers Alluviums

Lithology: gravel; alluvium

Troublesome Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 9 % of this area

Sandstone and siltstone; in Middle Park

Lithology: sandstone; siltstone

Coalmont Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 15 % of this area

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

Lithology: sandstone; conglomerate; shale; coal

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

Gabbro and mafic diorite and monzonite

Lithology: gabbro; diorite; monzonite

Modern alluvium (Phanerozoic | Cenozoic | Quaternary) at surface, covers 1 % of this area

Includes Piney Creek Alluvium and younger deposits

Lithology: alluvium

Bouldery gravel on old erosion surfaces in Front Range and Never Summer Mountains (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.7 % of this area

Lithology: gravel

Older glacial drift (Phanerozoic | Cenozoic | Quaternary) at surface, covers 0.5 % of this area

Lithology: glacial drift

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

Intermediate to felsic compositions

Lithology: plutonic rock (phanerit

Biotitic gneiss, schist, and migmatite (Proterozoic | Paleoproterozoic) at surface, covers 17 % 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

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

Mainly intermediate to felsic compositions; some mafic

Lithology: granitoid

Volcanic rocks in northwestern Colorado (Phanerozoic | Cenozoic | Tertiary) at surface, covers 4 % of this area

Mainly of intermediate compositions

Lithology: intermediate volcanic r

Granitic rocks of 1700-m.y. age group (Proterozoic | Paleoproterozoic) at surface, covers 12 % 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

Mesozoic rocks (Lower Phanerozoic | Mesozoic | Cretaceous-Triassic) at surface, covers 0.8 % of this area

Mainly Lower Cretaceous, Jurassic, and Triassic Fms

Lithology: clastic

Chugwater Fm (Phanerozoic | Mesozoic | Triassic) at surface, covers 0.2 % of this area

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

Lithology: sandstone; mudstone; limestone; evaporite

Landslide deposits (Phanerozoic | Cenozoic | Quaternary) at surface, covers 3 % 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 0.3 % of this area

Lithology: sandstone; mudstone; limestone

Older gravels and alluviums (Phanerozoic | Cenozoic | Quaternary) at surface, covers 0.6 % of this area

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

Lithology: gravel; alluvium

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

Sandstone and siltstone; west of Park Range

Lithology: sandstone; siltstone

Minturn Fm in west-central and south-central and other units (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian) at surface, covers 0.2 % 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 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

Morrison Fm and Sundance Fm (Phanerozoic | Mesozoic | Jurassic) at surface, covers 0.6 % of this area

Sundance Fm: Sandstone, shale, claystone, and limestone

Lithology: mudstone; sandstone; limestone

Granitic rocks of 1400-m.y. age group (Proterozoic | Mesoproterozoic) at surface, covers 6 % 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