A MAP SYNTHESIS ENGINE FOR CONSTRUCTING GEOLOGIC MAPS OF THE UNITED STATES

The geologic history of the U.S. is cataloged in thousands of geologic maps produced over many decades. However, the disparate nature of these individual maps makes it challenging to assess resources, research geologic histories, or systematically characterize natural hazards holistically across the nation. Following congressional direction to “bring together detailed national and continental-resolution 2D and 3D information produced throughout the Survey and by federal and state partners,” (House Report 116-100), we present a new synthesis of geologic maps across the conterminous U.S. in a relational database. Here we present a ‘national’ resolution map built with an infrastructure capable of hosting and producing other resolutions as well. This presentation focuses on the design and population of this database, which was built to ingest---and be updated by---GeMS-formatted geologic maps produced by the USGS National Cooperative Geologic Mapping Program. The database was constructed with three primary design goals; (1) to preserve in totality the interpretations of the source geologic maps, (2) to make the geologic content of those maps more discoverable by parsing queryable information, and (3) to facilitate the composition of maps of national scope that are legible as traditional geologic maps. We use this infrastructure to produce four synthesis map layers shown in accompanying presentations: Quaternary geology; the geology at the Earth’s surface; pre-Quaternary geology; and Precambrian geology. The database includes these thematic synthesis map layers, but also contains the original maps that were integrated to derive these layers, and linkages between geologic descriptions and standardized vocabularies to aide discoverability of geologic information. To complement the description of the database we provide some examples highlights to its functionality. This includes basic usages present in past compilations, such as searching for rocks of a particular material or age, but it also includes more advanced functionality enabled by the robust topologic relationship enforced by the GeMS standard; such as queries for particular unconformities or for faults truncating units of a specific age.