State Geologic Maps of All 50 States
- Collection of electronic versions of bedrock, surficial, and structural maps.
- http://geology.about.com/od/stategeologicmaps/

A Tapestry of Time and Terrain
- Geologic, topographic, and physiographic province maps of the U.S., from the U.S. Geological Survey.
- http://tapestry.usgs.gov/