Eocene prevolcanic sedimentary rocks

South-central: Arkosic sand and bouldery gravel of Echo Park Alluvium. Southwest: includes Telluride Conglomerate and Blanco Basin Fm (arkosic mudstone, sandstone, and conglomerate)
State Colorado
Name Eocene prevolcanic sedimentary rocks
Geologic age Tertiary
Lithologic constituents
Major
Sedimentary > Clastic > Sandstone > Arkose
Unconsolidated > Coarse-detrital > Gravelbouldery gravel
Minor
Sedimentary > Clastic > Conglomerate
Sedimentary > Clastic > Mudstone (Arkosic)
Sedimentary > Clastic > Sandstone
References

Tweto, Ogden, 1979, Geologic Map of Colorado: U.S. Geological Survey Special Geologic Map, scale 1:500,000.

NGMDB product
Counties Archuleta - Conejos - Custer - Dolores - Fremont - Gunnison - Hinsdale - Mineral - Montrose - Ouray - Park - San Juan - San Miguel - Teller