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 is maintained by the Map & GIS Library of Texas A & M University.
National Geophysical Data Center (NGDC) - NGDC provides stewardship, products and services for geophysical data describing the solid earth, marine, and solar-terrestrial environment, as well as earth observations from space.
Wisconsin Geological and Natural History Survey Digital Collection - This digital collection from the Wisconsin Geological and Natural History Survey includes bulletins, field photographs from the early 1900s, the field notebooks of Charles Van Hise, and early hydrographic lake maps.
