Highly detailed digital geologic maps of the US states (not including Alaska and Hawaii) with consistent descriptions (lithology, age, etc) from state to state. The original geologic data was from various sources and compiled by the USGS into KML format.
Click on a polygon to bring up information about that geologic unit. From there you can also access a more detailed description provided online by the USGS.
Each state is covered by a separate map and the size of the maps vary (Texas is 26 megabytes!!!) so give them time to load when you select a state. It may also take a minute or two for Google Earth to process the state map after it downloads. Google Earth may appear to have locked up as it’s crunching the data. You might also want to turn off the Terrain layer if the terrain bleeds through the map.