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

Geologic units in Montrose county, Colorado

[Additional scientific data in this geographic area]

Dakota Sandstone and Burro Canyon Fm (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 37 % 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 12 % 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

Chinle Fm (Phanerozoic | Mesozoic | Triassic) at surface, covers 0.5 % of this area

Red siltstone, sandstone, and limestone-pellet conglomerate

Lithology: siltstone; sandstone; conglomerate

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

Jurassic (1) sedimentary rocks in southeastern Utah (Middle to Late Jurassic) at surface, covers < 0.1 % of this area

Lithology: sandstone; mudstone; limestone; evaporite

Triassic and Jurassic sedimentary rocks in southeastern Utah (Early Jurassic) at surface, covers < 0.1 % of this area

Lithology: sandstone; mudstone; limestone

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

Includes Broadway and Louviers Alluviums

Lithology: gravel; alluvium

Pre-ash-flow andesitic lavas, breccias, tuffs, and conglomerates (Phanerozoic | Cenozoic | Tertiary) at surface, covers 0.5 % of this area

Includes several named units

Lithology: andesite; tuff; volcanic breccia (agglomerate)

Granitic rocks of 1400- and 1700-m.y. age groups, undivided, or, in Taylor River region, rocks with characteristics of Xg but U-Th-Pb zircon ages of Yg (Proterozoic | Paleoproterozoic Mesoproterozoic) at surface, covers 0.4 % of this area

Granitic rocks of 1400- and 1700-m.y. age groups, undivided, or, in Taylor River region, rocks with characteristics of Xg but U-Th-Pb zircon ages of Yg

Lithology: granitoid

Hermosa Fm (Phanerozoic | Paleozoic | Carboniferous Pennsylvanian) at surface, covers 0.5 % of this area

Arkosic sandstone, conglomerate, shale, and limestone; gypsum and salt in Paradox Member present in salt anticlines near Utah border

Lithology: sandstone; conglomerate; shale; limestone; evaporite

Glen Canyon Group and Chinle Fm (Phanerozoic | Mesozoic | Triassic Jurassic) at surface, covers 4 % of this area

In southwest, Glen Canyon Group consists of Navajo Sandstone, Kayenta Fm (red siltstone, shale, and sandstone) and Wingate Sandstone; Chinle is red siltstone

Lithology: sandstone; siltstone; shale

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

Telluride conglomerate of Eocene prevolcanic sedimentary rocks (Te) and Cimarron Ridge Fm (Phanerozoic | Mesozoic Cenozoic | Cretaceous Tertiary) at surface, covers < 0.1 % of this area

In northwestern San Juan Mountains. Cimarron Ridge Fm: volcanic breccia and conglomerate.

Lithology: conglomerate; volcanic breccia (agglomer

Morrison Fm, Summerville Fm, and Entrada Sandstone (Phanerozoic | Mesozoic | Jurassic) at surface, covers 24 % of this area

Summerville Fm: Shale and siltstone

Lithology: mudstone; sandstone

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

Granitic rocks of 1400-m.y. age group (Proterozoic | Mesoproterozoic) at surface, covers 0.2 % 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

Wingate Sandstone and Chinle Fm (Phanerozoic | Mesozoic | Triassic) at surface, covers 0.5 % of this area

Lithology: sandstone; siltstone; conglomerate

Morrison, Wanakah, and Entrada Fms (Phanerozoic | Mesozoic | Jurassic) at surface, covers 1 % of this area

Lithology: mudstone; sandstone; 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

Landslide deposits (Phanerozoic | Cenozoic | Quaternary) at surface, covers 6 % of this area

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

Lithology: landslide; talus; colluvium

Quaternary eolian deposits (Quaternary) at surface, covers < 0.1 % of this area

Lithology: eolian

Jurassic (2) sedimentary rocks in southeastern Utah (Late Jurassic) at surface, covers < 0.1 % of this area

Lithology: shale; sandstone; conglomerate

Moenkopi Fm and Cutler Fm (Phanerozoic | Paleozoic Mesozoic | Permian Triassic) at surface, covers 0.5 % of this area

Red siltstone and sandstone

Lithology: siltstone; sandstone

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

Mesaverde Fm, undivided (Phanerozoic | Mesozoic | Cretaceous) at surface, covers 0.1 % 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

Granitic rocks of 1700-m.y. age group (Proterozoic | Paleoproterozoic) at surface, covers 0.1 % 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

Morrison Fm and Wanakah Fm (Junction Creek Sandstone Member at or near top; Pony Express Limestone Member at base) (Phanerozoic | Mesozoic | Jurassic) at surface, covers 0.3 % of this area

Wanakah Fm: Sandstone, shale, limestone, and local gypsum

Lithology: mudstone; sandstone; limestone; evaporite

Eocene prevolcanic sedimentary rocks (Phanerozoic | Cenozoic | Tertiary) at surface, covers < 0.1 % of this area

South-central: Arkosic sand and bouldery gravel of Echo Park Alluvium. Southwest: includes Telluride Conglomerate and Blanco Basin Fm (arkosic mudstone, sandstone, and conglomerate)

Lithology: sandstone; conglomerate; mudstone

Modern alluvium (Phanerozoic | Cenozoic | Quaternary) at surface, covers 5 % of this area

Includes Piney Creek Alluvium and younger deposits

Lithology: alluvium

Kayenta Fm, Wingate Sandstone, and Chinle Fm (Phanerozoic | Mesozoic | Triassic) at surface, covers 2 % of this area

Kayenta Fm: red siltstone, shale, and sandstone. Chinle Fm: red siltstone and sandstone

Lithology: sandstone; siltstone; shale

Cretaceous (1) sedimentary rocks in southeastern Utah (Cretaceous) at surface, covers < 0.1 % of this area

Lithology: sandstone; shale

Quaternary landslides (Quaternary) at surface, covers < 0.1 % of this area

Lithology: landslide