GeMS (Geologic Map Schema)

GeMS (Geologic Map Schema)

A Standard Format for the Digital Publication of Geologic Maps

GeMS (Geologic Map Schema, formerly NCGMP09) is the standard schema for geologic map publications funded by the U.S. Geological Survey's 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 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. Please note that the schema and documentation, and the software tools that support it will evolve over time, in response to the needs of users and geologic mappers, and to advances in technology. A Standard Format for the Digital Publication of Geologic Maps, USGS Techniques and Methods 11-B10, is the latest version of GeMS. This website was set up to help geologists understand the GeMS schema in a more managable way by breaking down the report and other information. All questions or comments about GeMS should be directed via email to



U.S. Geological Survey National Cooperative Geologic Mapping Program, 2020, GeMS (Geologic Map Schema)—A standard format for the digital publication of geologic maps: U.S. Geological Survey Techniques and Methods, book 11, chap. B10, 74 p.,

Website Header and Report Cover Image:

Geologic map of the western United States and surrounding areas, extracted from the “Geologic map of North America” (Reed and others, 2005; database from Garrity and Soller, 2009). Image downloaded from the National Geologic Map Database (

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