This report describes and defines GeMS (for Geologic Map Schema), 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 National Cooperative Geologic Mapping Program of the U.S. Geological Survey, 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.

GeMS provides for the encoding in digital form of the content contained in individual geologic maps published by the U.S. Geological Survey and by state geological surveys. The design is focused on the publication, transfer, and archiving of map data and less on the creation of map data, the visual representation of map data, or the compilation of data from many different map sources.

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. The database design contained herein will significantly promote that goal. All questions or comments about GeMS should be directed via email to gems@usgs.gov.