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

Geologic units in La Plata county, Colorado

[Additional scientific data in this geographic area]

Cutler Fm (Phanerozoic | Paleozoic | Permian) at surface, covers 9 % of this area

Arkosic sandstone, siltstone, and conglomerate

Lithology: sandstone; siltstone; conglomerate

Landslide deposits (Phanerozoic | Cenozoic | Quaternary) at surface, covers 0.2 % of this area

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

Lithology: landslide; talus; colluvium

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

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

Lithology: mudstone; sandstone; limestone

Felsic and hornblendic gneisses, either separate or interlayered (Proterozoic | Paleoproterozoic) at surface, covers 3 % 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

Cliff House Sandstone (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area

Cliff House Sandstone; transgressive marine sandstone; Campanian

Lithology: sandstone; shale

Quartzite, conglomerate, and interlayered mica schist (Proterozoic | Paleoproterozoic) at surface, covers 0.4 % of this area

Quartzite, conglomerate, and interlayered mica schist

Lithology: quartzite; conglomerate; mica schist

Granitic rocks of 1400-m.y. age group (Proterozoic | Mesoproterozoic) at surface, covers 5 % 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

Older glacial drift (Phanerozoic | Cenozoic | Quaternary) at surface, covers < 0.1 % of this area

Lithology: glacial drift

Modern alluvium (Phanerozoic | Cenozoic | Quaternary) at surface, covers 4 % of this area

Includes Piney Creek Alluvium and younger deposits

Lithology: alluvium

Kirtland and Fruitland Formations (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area

Kirtland and Fruitland Formations; coal-bearing, coal primarily in the Fruitland; Campanian to Maastrichtian

Lithology: sandstone; mudstone; coal

Leadville Limestone, Gilman Sandstone, Dyer Dolomite, and Parting Fm (Phanerozoic | Paleozoic | Ordovician Silurian(?) Devonian) at surface, covers < 0.1 % of this area

Parting Fm: quartzite and shale.

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

Pictured Cliffs Sandstone and Lewis Shale (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 4 % of this area

Lithology: sandstone; 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

Rico and Hermosa Fms (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian) at surface, covers 9 % of this area

Arkosic sandstone, conglomerate, shale, and limestone. Includes at base in some areas siltstone and shale of Molas Fm or Larsen Quartzite

Lithology: sandstone; conglomerate; shale; limestone; mudstone

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

Intermediate to felsic compositions

Lithology: plutonic rock (phanerit

Mesaverde Fm, undivided (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.7 % 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

Laramide intrusive rocks (Phanerozoic | Mesozoic Cenozoic | Cretaceous Tertiary) at surface, covers 0.6 % of this area

Mainly intermediate to felsic compositions; some mafic

Lithology: granitoid

Kirtland Shale and Fruitland Fm (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 2 % of this area

Shale, sandstone, and major coal beds

Lithology: shale; sandstone; coal

Menefee Formation (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area

Menefee Formation; mudstone, shale, and sandstone; coal-bearing

Lithology: fine-grained mixed clastic; coal; limestone

Glacial drift (Phanerozoic | Cenozoic | Quaternary) at surface, covers 0.3 % of this area

Includes some unclassified glacial deposits

Lithology: glacial drift

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

Nacimiento Formation; Paleocene, San Juan Basin

Lithology: sandstone; shale; conglomerate

Gravels and alluviums (Phanerozoic | Cenozoic | Quaternary) at surface, covers 5 % of this area

Includes Broadway and Louviers Alluviums

Lithology: gravel; alluvium

Pictured Cliffs Sandstone (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area

Pictured Cliffs Sandstone; prominent cliff-forming marine sandstone

Lithology: sandstone; mudstone

Dakota Sandstone and Burro Canyon Fm (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 2 % of this area

Sandstone, shale, and conglomerate. In northwest and west-central: Lower Cretaceous. In southwest: Lower and Upper Cretaceous.

Lithology: sandstone; shale; conglomerate

Mancos Shale (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 4 % 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

Animas Formation (Phanerozoic | Mesozoic Cenozoic | Cretaceous Tertiary) at surface, covers < 0.1 % of this area

Animas Formation; in northeast San Juan Basin

Lithology: clay or mud; tuff; clastic

Lewis Shale (Phanerozoic | Mesozoic | Cretaceous) at surface, covers < 0.1 % of this area

Lewis Shale; marine shale and mudstone

Lithology: shale; fine-grained mixed clastic; limestone

Menefee Fm and Point Lookout Sandstone (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 2 % of this area

sandstone, shale, and coal; sandstone

Lithology: sandstone; shale; coal

San Jose Fm (Phanerozoic | Cenozoic | Tertiary) at surface, covers 11 % of this area

Siltstone, shale, and sandstone

Lithology: siltstone; shale; sandstone

Dolores Fm (Phanerozoic | Mesozoic | Triassic) at surface, covers 2 % of this area

Red siltstone, shale, sandstone, and limestone-pellet conglomerate

Lithology: siltstone; shale; sandstone; conglomerate

San Jose Formation (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.2 % of this area

San Jose Formation; Eocene, San Juan Basin

Lithology: medium-grained mixed clastic

Animas Fm (Phanerozoic | Mesozoic Cenozoic | Cretaceous Tertiary) at surface, covers 11 % of this area

Arkosic sandstone, shale, and conglomerate; contains abundant volcanic materials; Upper Cretaceous volcaniclastic McDermott Member at base

Lithology: sandstone; shale; conglomerate; mixed clastic/volcanic

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 2 % of this area

Elbert Fm: shale and sandstone.

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

Cliff House Sandstone (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 11 % of this area

Lithology: sandstone

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

Shale and sandstone

Lithology: shale; sandstone

Uncompahgre Fm (Proterozoic | Paleoproterozoic Mesoproterozoic) at surface, covers 0.3 % of this area

Quartzite, slate, and phyllite

Lithology: quartzite; slate; phyllite

Alkalic and mafic rocks in small plutons, and diabase and gabbro dikes (Proterozoic | Mesoproterozoic) at surface, covers 0.2 % of this area

Alkalic and mafic rocks in small plutons, and diabase and gabbro dikes

Lithology: granitoid; diabase; gabbro