National Geologic Map Database

In 2014-2017, this database design was extensively reviewed and test-implemented by the U.S. Geological Survey and the State Geological Surveys. During this process, certain modifications and clarifications to the current version (NCGMP09v1.1) were identified. A new version is now being prepared for formal publication by the USGS. This new version is given a new, more pronounceable name — "GeMS" (Geologic Map Schema). Questions or comments may be directed here.

  • GeMS draft manuscript — "GeMS" (Geologic Map Schema) is the latest version of NCGMP09 (see the Archive, below, for NCGMP09 documentation). This draft manuscript is still provisional; however, it has passed Peer Review, and it is now being prepared for technical edit and, ultimately, for formal publication by the USGS. Please contact us at gems@usgs.gov with questions and comments.
  • GeMS Toolkit — ArcGIS tools for GeMS schema (latest version, 4/02/18, from Github site)
  • GeMS Toolkit site, on Github

  • Archive of previous versions and presentations
  • Progress Report on the evaluation and implementation of NCGMP09 (Sept. 25, 2013)


Example maps published in GeMS format:


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). Its design specifies encoding the content analogous to that contained in a traditional geologic map published by the USGS and by State Geological Surveys. Implementation in ESRI software is described in GeMS, in order to adhere to USGS policy and because this is the GIS most commonly used in the USGS, in the State Geological Surveys, and in the larger community.

This schema is an outcome of nearly two decades of work among numerous individuals and projects, in the NCGMP and in other programs and in many agencies. In particular, during this period the National Geologic Map Database project (NGMDB) has been charged under the Geologic Mapping Act to support the development of geologic map standards and guidelines. Throughout this time, it has been clear that there is no single "right" approach, database needs vary from project to project, and these needs may contrast markedly with the long-term requirements for the national database. This schema, as noted, is intended to address the needs of geologic mapping projects particularly for data delivery, and so we sought consensus on a design that met those needs.

NCGMP09 was introduced at the Digital Mapping Techniques '09 meeting (May, 2009), as version 0.8.2, in order to solicit preliminary comments and testing. Version 1.0 was released October 14, 2009, for presentation at the Geological Society of America's Annual Meeting. In the months following, more extensive evaluations were received, and in response the design evolved. The revised version, as published in the DMT'09 Proceedings and available above, reflects the current manifestation of NCGMP09 (version 1.1). During that timeframe, NCGMP09 development was supported by the USGS/AASG National Geologic Map Database Project and the USGS Pacific Northwest Geologic Mapping Project (Ralph Haugerud, Stephen Richard, David Soller, and Evan Thoms). Since then, implementation and potential revisions or enhancements to NCGMP09 have been conducted by a wider group of colleagues (see Progress Report of Sept. 25, 2013). In 2014-2017, the schema and documentation were extensively reviewed and test-implemented by the U.S. Geological Survey and the State Geological Surveys. During this process, the need for certain modifications and clarifications was identified. The revised version of NCGMP09, renamed as GeMS, is now being prepared for formal publication by the USGS in early 2018.

Regarding availability and maintenance of this database design, under the authority of the Geologic Mapping Act of 1992 (and subsequent reauthorizations), the National Geologic Map Database project will function on behalf of the NCGMP as coordinator of database design changes and maintenance. This activity will be conducted in cooperation with NCGMP projects and other identified stakeholders (e.g., the Association of American State Geologists). Long-terms plans include proposing GeMS as the standard supported by the Federal Geographic Data Committee. 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.

Archive of previous versions and related information