Geologic units in Mesa county, Colorado

Additional scientific data in this geographic area

Morrison Fm, Summerville Fm, and Entrada Sandstone (Jurassic) at surface, covers 17 % of this area

Summerville Fm: Shale and siltstone

Wasatch Fm (including Fort Union equivalent at base) and Ohio Creek Fm (Tertiary) at surface, covers 13 % of this area

Claystone, mudstone, sandstone, and conglomerate

Mancos Shale (Cretaceous) at surface, covers 13 % 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 Frontier and Mowry Members (Kmfm), or these and the Dakota Sandstone (Kfd) are distinguished, map unit (Km) consists of shale above Frontier Member. In Southwest: Lower part contains Juana Lopez Member (Kmj)

Kayenta Fm, Wingate Sandstone, and Chinle Fm (Triassic) at surface, covers 11 % of this area

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

Dakota Sandstone and Burro Canyon Fm (Cretaceous) at surface, covers 6 % of this area

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

Wingate Sandstone and Chinle Fm (Triassic) at surface, covers 5 % of this area

Wingate Sandstone and Chinle Fm

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

Includes some unclassified glacial deposits

Hunter Canyon Fm (Cretaceous) at surface, covers 5 % of this area

Sandstone and shale

Modern alluvium (Quaternary) at surface, covers 3 % of this area

Includes Piney Creek Alluvium and younger deposits

Landslide deposits (Quaternary) at surface, covers 3 % of this area

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

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

Includes Broadway and Louviers Alluviums

Green River Fm--Lower Part (Tertiary) at surface, covers 2 % of this area

Shale, sandstone, marlstone, and limestone in Anvil Points, Garden Gulch, and Douglas Creek Members; in Piceance basin

Older gravels and alluviums (Quaternary) at surface, covers 2 % of this area

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

Basalt flows and associated tuff, breccia, and conglomerate of late-volcanic bimodal suite (Tertiary) at surface, covers 2 % of this area

Includes basalts of Hinsdale Fm in San Juan Mountains - Servilleta Fm in San Luis Valley and many other occurrences

Moenkopi Fm and Cutler Fm (Triassic-Permian) at surface, covers 2 % of this area

Red siltstone and sandstone

Mount Garfield Fm and Sego Sandstone (Cretaceous) at surface, covers 1 % of this area

Sandstone and shale; major coal beds in lower part of Mount Garfield

Glen Canyon Group and Chinle Fm (Jurassic-Triassic) at surface, covers 1 % 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

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 (Early-Middle Proterozoic) at surface, covers 1 % 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

Biotitic gneiss, schist, and migmatite (Early Proterozoic) at surface, covers 0.9 % of this area

Locally contains minor hornblende gneiss, calc-silicate rock, quartzite, and marble. Derived principally from sedimentary rocks

Green River Fm--Parachute Creek Member (Tertiary) at surface, covers 0.8 % of this area

Parachute Creek Member--Oil shale, marlstone, and siltstone; in Piceance basin

Uinta Fm (Tertiary) at surface, covers 0.6 % of this area

Sandstone and siltstone; in Piceance basin. Formerly Evacuation Creek Member of Green River Fm

Mesaverde Fm, undivided (Cretaceous) at surface, covers 0.5 % 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.

Granitic rocks of 1400-m.y. age group (Middle Proterozoic) at surface, covers 0.4 % 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

Eolian deposits (Quaternary) at surface, covers 0.4 % of this area

Includes dune sand and silt and Peoria Loess

Green River Fm (Tertiary) at surface, covers 0.3 % of this area

Marlstone, sandstone, and oil shale

Mesaverde Group or Fm--Upper part (Cretaceous) at surface, covers 0.3 % of this area

In Moffat and Rio Blanco Counties, sandstone, shale, and coal beds above Sego Sandstone. Along Grand Hogback south of Colorado River, sandstone and shale above coal-bearing sequence

Granitic rocks of 1700-m.y. age group (Early Proterozoic) at surface, covers 0.3 % 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; also, unnamed granitic rocks

Ancient alluvium (Quaternary-Tertiary) at surface, covers 0.2 % of this area

In isolated patches that may not all be of the same age

Hermosa Fm (Pennsylvanian) at surface, covers 0.2 % of this area

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

Glen Canyon Group (Early Jurassic) at surface, covers < 0.1 % of this area

Glen Canyon Group (Navajo Ss, Kayenta Fm, and Wingate Ss). Includes Rainbow Bridge.

Mancos Shale (Late Cretaceous) at surface, covers < 0.1 % of this area

Mancos Shale (Masuk Shale Mbr, Emery Sandstone Mbr, Blue Gate Shale Mbr, Ferron Sandstone Mbr, and Tununk Shale Mbr).

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

Older alluvial deposits

Cutler Fm (Permian) at surface, covers < 0.1 % of this area

Arkosic sandstone, siltstone, and conglomerate

Schist, gneiss, and granite (Precambrian) at surface, covers < 0.1 % of this area

Schist, gneiss, and granite (1.5 billion years old).

Dakota Ss and Cedar Mtn. or Burro Canyon Formations (Cretaceous) at surface, covers < 0.1 % of this area

Dakota Ss and Cedar Mtn or Burro Canyon Formations.

Bluff Ss, Summerville Fm, Curtis Fm, Entrada Ss, and Carmel Formation (Middle to Late Jurassic) at surface, covers < 0.1 % of this area

Bluff Ss, Summerville Fm, Curtis Fm, Entrada Ss, and Carmel Formation. Includes Arches National Park.

Alluvium and colluvium (Quaternary) at surface, covers < 0.1 % of this area

Alluvium and colluvium

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

Eolian deposits

Middle Tertiary intrusive rocks (Tertiary) at surface, covers < 0.1 % of this area

Intermediate to felsic compositions

Morrison Formation (Brushy Basin and Salt Wash Members) (Late Jurassic) at surface, covers < 0.1 % of this area

Morrison Formation (Brushy Basin and Salt Wash Members).

Chinle Shale and Shinarump Conglomerate Member (Late Triassic) at surface, covers < 0.1 % of this area

Chinle Shale and Shinarump Conglomerate Member.

Cutler Group (Pennsylvanian to Early Permian) at surface, covers < 0.1 % of this area

Cutler Group (White Rim Ss, De Chelly Ss, Organ Rock Shale, Cedar Mesa Ss, Halgaito Fm, and Elephant Canyon Fm). Includes Natural Bridges National Monument.