SURFICIAL AND BEDROCK GEOLOGIC MAPS OF THE CORTEZ 1-DEGREE BY 2-DEGREES QUADRANGLE, UTAH AND COLORADO

We present surficial and bedrock geologic map databases of the Cortez quadrangle, SE Utah and SW Colorado, USA. Following standards of the Seamless Integrated Geologic Mapping (SIGMa) extension to the Geologic Map Schema (GeMS), we compiled point, line, and polygon data primarily from 1:250,000 to 1:24,000 scale published maps. Methods include ingesting data unmodified from original source maps, modifying data for target scales between 1:100,000 and 1:50,000, improving the spatial resolution of features (e.g., using 1 m LiDAR DEMs), modifying features for continuity across source map boundaries, extending bedrock contacts and faults under surficial deposits, modifying attributes via additional data (e.g., published geochronology), and limited new mapping from field work or remote sensing. Surficial compilation highlights Pleistocene to Holocene eolian, alluvial, and mass wasting deposits in the Canyon Lands and Navajo sections of the Colorado Plateau, as well as glacial deposits in the Southern Rocky Mountains. Bedrock geology mostly includes sedimentary strata of Cordilleran orogenic basins, the tectonic structures that deform them, intrusions related to Cordilleran foreland magmatism, and laccoliths associated with the ignimbrite flare-up. Challenges include addressing source map variations in rock unit description, nomenclature, and contact location, plus splitting traditional maps into separate surficial and bedrock compilations. Surficial map units are characterized by material, age, and genetic type (instead of strictly defined map units from local source maps) so that similar deposits can be broadly queried by attributes within physiographic provinces. Bedrock map units include relationships from member, formation, group, to geologic provinces to preserve the spatial resolution of split units while maintaining the map-wide queryable properties of lumped units. In both databases, feature level attributes are preserved to provide more detail beyond typical descriptions of map units as well as in point and line attributes. These compilations provide powerful resources for the geospatial evaluation of geologic features in this quadrangle and the southwestern USA, filling in a transect from the Rio Grande rift to the Basin and Range as a contribution to the National Geologic Map.