Geologic Maps of the USA
Geologic Map of the Lower 48 States
A small version of the huge U.S. Geological Survey map with a bigger one behind it.
Digital Shaded-Relief Map of the United States
No state lines, no cities, no labels at all, just the pure shape of the land surface of the 48 states, courtesy of the U.S. Geological Survey (1152x718 pixels).
Geologic Map of the United States
The classic 1974 USGS map of the 48 states is presented in easy-to-use detail by Prof. William Menke of Columbia University.
USGS Quaternary Fault and Fold Database
Information on faults and associated folds in the United States that are believed to be sources of M>6 earthquakes during the Quaternary.
USGS National Geologic Map Database
Everything that's available online is here on one page. A must-have for any outing.
U.S. Geologic Radon Potential
This map is from the U.S. Geological Survey, and should be just the beginning of your investigation into the radon potential of the place where you live.
U.S. Mercury Alerts
Where levels of mercury in the water become a concern, the authorities issue a health advisory that recommends limits on the amount of fish you should eat—especially if you're pregnant or an infant
U.S. Natural Radiation
Levels of background radiation as measured by aerial surveys over the continental United States.
U.S. Uranium Concentrations
Areas rich and poor in uranium stand out on this map from the U.S. Geological Survey.