The USGS National Geologic Map Database.
Searchable catalog of paper and digital geologic maps, mostly for the U.S.
Geologic Maps of the States
Maps of the states created by the United States Geologic Survey.
Geologic Map of Texas
High resolution, detailed geologic map of Texas from the Texas Water Development Board.
Geologic Maps of Texas
Texas Bureau of Economic Geology maps from the University of Texas Walter Geologic Library.
Information about Geologic Maps from the American Association of Petroleum Geologists.
An interactive geological map of the British Isles.