National Geologic Map Database

The National Geologic Map Database (NGMD) is a collaborative effort primarily involving the United States Geological Survey (USGS) and the Association of American State Geologists (AASG) to develop “a distributed archive of standardized geoscience information for the nation.” The NGMD website has links to a map catalog, geologic names, a map interface, and information about geologic mapping projects in progress. (Please note that some parts of this database are still under construction and may not be currently available.)