Geologic units in Mineral county, Colorado

Additional scientific data in this geographic area

Ash-flow tuff of main volcanic sequence (Tertiary) at surface, covers 52 % of this area

Includes many named units

Intra-ash flow quartz latitic lavas (Tertiary) at surface, covers 12 % of this area

Intra-ash flow quartz latitic lavas

Pre-ash-flow andesitic lavas, breccias, tuffs, and conglomerates (Tertiary) at surface, covers 8 % of this area

Includes several named units

Landslide deposits (Quaternary) at surface, covers 7 % of this area

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

Glacial drift (Quaternary) at surface, covers 6 % of this area

Includes some unclassified glacial deposits

Intra-ash flow andesitic lavas (Tertiary) at surface, covers 6 % of this area

Intra-ash flow andesitic lavas

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

Includes Piney Creek Alluvium and younger deposits

Oligocene sedimentary rocks (Tertiary) at surface, covers 3 % of this area

Northwest: includes Duchesne River Fm (sandstone and shale; includes some rocks of Eocene age) and Bishop Conglomerate near Utah border. South-central: includes Florissant Lake Beds (tuffaceous shale and tuff) and Antero Fm (limestone tuff, tuffaceous sandstone, and conglomerate). Southwest: includes Creede Fm (tuffaceous siltstone, sandstone, conglomerate) and gravels interbedded with volcanic rocks northeast and southeast of Gunnison

Basalt flows and associated tuff, breccia, and conglomerate of late-volcanic bimodal suite (Tertiary) at surface, covers 1 % of this area

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

Animas Fm (Tertiary-Cretaceous) at surface, covers 0.5 % of this area

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

Pictured Cliffs Sandstone and Lewis Shale (Cretaceous) at surface, covers 0.5 % of this area

Pictured Cliffs Sandstone and Lewis Shale

Middle Tertiary intrusive rocks (Tertiary) at surface, covers 0.4 % of this area

Intermediate to felsic compositions

Gravels and alluviums (Quaternary) at surface, covers 0.2 % of this area

Includes Broadway and Louviers Alluviums

Eocene prevolcanic sedimentary rocks (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)

Mesaverde Fm, undivided (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.

Mancos Shale (Cretaceous) at surface, covers < 0.1 % 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)