This digital data release contains geospatial geologic data compiled for the Lamar 250k quadrangle, a region in eastern Colorado and western Kansas, which is predominantly covered by Quaternary deposits that overlay Cretaceous bedrock. Geologic data, compiled from published sources, include the location and characteristics of geologic contacts and faults, mapped geologic polygons, and ammonite fossils. The geologic database includes spatial feature classes that collectively contain the geologic information that are presented in the previously published map plate. The spatial data are accompanied by non-spatial tables that describe the sources of geologic information, a description of geologic map units, a glossary of terms, and a Data [...]