THE GEMS DATABASE SCHEMA FOR GEOLOGIC MAPS – ENSURING COMPLIANCE WITH THE STANDARD

The Geologic Map Schema ("GeMS") is a new standardized database schema - that is, a database design - for the digital publication of geologic maps. It originally was intended for geologic mapping funded by the USGS National Cooperative Geologic Mapping Program (NCGMP), but its use can be extended to other programs and agencies as well. It is intended to bridge the gap between traditional geologic mapping and GIS communities at an operational level. The schema was first presented at the Digital Mapping Techniques annual meeting in 2009, and it has been extensively evaluated and test-implemented in the decade since then. Although GeMS is designed for a single-map database, it also is intended to provide a stepping stone toward the development of multiple-map databases, in particular the National Geologic Map Database (NGMDB). The Geologic Mapping Act of 1992, and its subsequent reauthorizations, mandate the creation of a national archive of standardized geologic map content. The NGMDB functions on behalf of the NCGMP as coordinator of database design and maintenance, in cooperation with the Association of American State Geologists.

As digital geologic maps are prepared according to the GeMS schema, for incorporation into the NGMDB's archive, a method of ascertaining compliance with this standard must be developed. To this end, we have written scripts that: (a) evaluate topology, database schema, and most of the content; and (b) compare formal geologic names shown in the Description of Map Units with names compiled in the U.S. Geologic Names Lexicon (Geolex). These scripts are now being evaluated, and will become publicly available later this year.