MAP DATABASE FOR SURFICIAL MATERIALS IN THE CONTERMINOUS UNITED STATES

The USGS National Cooperative Geologic Mapping Program (NCGMP) works with the State geological surveys to identify priority areas for mapping of surficial materials (for example, in areas of complex and poorly understood deposits of various sediment types, where metropolitan areas are experiencing rapid growth). To help locate these priority areas, a quickly prepared, modern, synoptic overview of the surficial materials and weathered bedrock was needed. Such a map was assembled, using existing map databases, for the conterminous United States (Soller and Reheis, 2004, scale 1:5,000,000; http://pubs.usgs.gov/of/2003/of03-275/). That map was produced as a PDF file, from an Adobe Illustrator-formatted version of the provisional GIS database. The provisional GIS files then were further processed without modifying the content of the published map, and recently published as USGS DS-425 (http://pubs.usgs.gov/ds/425/).

This map database provides an overview of current knowledge of the composition and distribution of surficial materials in the conterminous United States, and also serves to illustrate for educational and planning purposes the general nature and distribution of the Nation's surficial materials at land surface. As evidence of its utility, prior to its digital publication it had already been adapted for use in the new national Terrestrial Ecosystems classification system (USGS Professional Paper 1768, supported by a set of maps), and also is being applied to regional-scale research and mapping of plant distribution, the effects of geologic conditions on animal habitats and distribution, air-mass trajectories (for example, where do the winds blow the salty materials derived from dry lake beds), and earthquake shear wave velocities in the U.S. We encourage comments on the map’s content, and suggestions for improving it for any subsequent versions.