DATABASE OF THE GEOLOGIC MAP OF NORTH AMERICA—ADAPTED FROM THE MAP BY J.C. REED, JR. AND OTHERS (2005)

In 1998, the Geological Society of America (GSA) and the U.S. Geological Survey (USGS) National Geologic Map Database project (NGMDB) agreed to cost-share the digital cartographic preparation of the Geologic Map of North America (GMNA). Development of the GMNA for final print production required digitization of various hand-drawn geologic base maps. The resultant digital data allowed the NGMDB project to begin development of a prototype database design. In 2005, the GMNA was printed and released as the final product of the GSA’s Decade of North American Geology project (Reed, J.C. Jr., Wheeler, J.O., and Tucholke, J.E., compilers, 2005, Geologic Map of North America: Decade of North American Geology Continental Scale Map 001, Boulder, Geological Society of America, scale 1:5,000,000). In 2006, the NGMDB project began to create a Geographic Information System (GIS) compatible database. A complete GIS dataset with accompanying metadata files for the GMNA has now been prepared (http://pubs.usgs.gov/ds/424/). The dataset contains all geologic and base-map information shown on the two printed map sheets and the accompanying explanation sheet. The dataset includes over 900 individual geologic map units, nearly 150 of which are offshore.

With publication of this database, the preparation of any type of simplified map is made significantly easier. The database provides a more accessible means to explore the map information and to compare and analyze it in conjunction with other types of information (for example, land-use, soils, biology) in order to better understand the complex inter-relations among factors that affect Earth resources, hazards, ecosystems, and climate.