Geologic Atlas of the United States
The Geologic Atlas of the United States is a set of 227 folios published by the U.S. Geological Survey between 1894 and 1945. Each folio includes both topographic and geologic maps for each quad represented in that folio, as well as description of the basic and economic geology of the area. The Geologic Atlas collection was digitized by Map and GIS Collections and Services and is held in the Repository. Each map has been georectified for GIS and .kml files created for use with GoogleEarth.