http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
this map compiled and drafted by R.D. Christiansen, Geologist, Western GeoGraphics.
"Map geology and geologic explanation compiled and adapted from Geologic map of Colorado [U.S.G.S. (Ogden Tweto), 1979]."
Includes "Index to USGS 1⁰ x 2⁰ sheets" notes, and geographic location map.