Geologic maps can be obtained through many sources. In particular, there are topographic maps put out by the U.S. Geological Survey. These maps can also be obtained from the government agency’s Internet site at http://www.usgs.gov/pubprod/. Also check the Web sites of the state you are interested in because many times the state’s geological surveys will have maps available. There are also somewhat useable maps of certain areas of the country, including terrain, highway, and satellite maps, on the site “Google Maps” (currently at http://maps.google.com/maps).