Geologic Map of the 48 States
(c) 2002 Andrew Alden, licensed to About.com, Inc.
This is a miniature version of the great Geologic Map of the Conterminous United States (that's a fancy name for the lower 48 states). Click on it (or here) for a version that's 859x541 pixels. To explore the map of endless detail, visit the U.S. Geological Survey's Tapestry of Time and Terrain site.
