MODIFIED GEOLOGIC MAPPING SCHEMA (GEMS) FOR REGIONAL GEOLOGIC MAP COMPILATION: AN EXAMPLE FROM THE USGS GEOLOGIC FRAMEWORK OF THE INTERMOUNTAIN WEST PROJECT

National- to regional-scale geologic datasets are fundamental components of scientific investigations, resource and natural hazard assessment, and environmental management. Geoscience end users of these databases benefit from standardization of data schemas. The “Geologic Mapping Schema” (GeMS), adopted by the USGS National Cooperative Geologic Mapping Program, provides a standard for geologic mapping information; however, GeMS was designed to capture data from a single geologic map with finite geographic and geologic extent. Construction of regional- to national-scale datasets requires accommodation of an indeterminate range of geologic information, consequently requiring modifications to standard GeMS. Modifications to GeMS for the Geologic Framework of the Intermountain West project facilitate digital compilation in an enterprise, multi-user environment and accommodate a wide range of geologic information well-suited to the geologic diversity encountered with regional compilation. This “regional”-GeMS schema: (1) splits surficial and bedrock structural and map unit information into topologically distinct feature classes allowing concurrent surficial/bedrock compilation efforts; (2) incorporates detailed descriptive information relevant to local investigations in addition to general characterization of units more suited to regional studies; (3) includes attributes that place each geologic unit in the context of tectonic or volcanic events; (4) establishes unique unit identifiers based on a combination of local stratigraphic nomenclature and attributes for geologic event associations eliminating the onerous task of maintaining unique lithostratigraphic nomenclature for regional or national datasets; and (5) captures source reference information at the feature level. Use of a data standard is immaterial if compilation and attribution is incorrectly or inconsistently used, which necessitates constant collaboration among project scientists and implementation of standard workflows when possible. We are optimistic that effective workflows, attribution, and compilation methods utilized successfully at a project level consisting of 13 scientists can be scaled up to a multi-state or national scale initiative with many tens of scientists.