THE NATIONAL GEOLOGIC MAP DATABASE -- A RESOURCE FOR GEOLOGIC MAPPING

From its mandate in the Geologic Mapping Act of 1992, the U.S. Geological Survey (USGS) and the Association of American State Geologists (AASG, representing the State geological surveys) have worked together to build the National Geologic Map Database (NGMDB, http://ngmdb.usgs.gov/). The NGMDB is stipulated to be a standardized, "national archive" of geoscience information (maps and reports, both published and unpublished), made available to the public to support decisionmaking, research, and other needs. The website for this resource opened in 1996. Each month, it serves more than 60,000 users, who visit the site roughly a quarter-million times.

To support geologic mappers, online resources provided by or linked from the NGMDB include:

1) the U.S. Geologic Names Lexicon (Geolex), the standard reference for the Nation's stratigraphic nomenclature;

2) the Geoscience Map Catalog, which contains citations and Web links to >100,000 maps, stratigraphic charts, and reports by >630 publishers, many containing GIS data and map images (map images are available in geotiff, jpg, and pdf format);

3) mapView, an interactive viewer that provides a visual front-end to selected bedrock and surficial geologic maps in the Catalog;

4) standards and techniques that are essential to compilation and production of geologic maps and databases (including the FGDC geologic map symbolization standard, the NCGMP09 database schema, and reports and presentations from the twenty annual Digital Mapping Techniques workshops); and

5) topoView, a popular new interface that enables users to quickly search, browse, and download USGS topographic maps.