A Tapestry of Time and Terrain: State Boundary Map

This United States Geological Survey (USGS) web-site contains an interactive index map of the United States combining both topography and geology of the country. Each state can be clicked on for a geologic map and key of the rock ages and locations in that particular state. The rock ages can then be clicked on leading to general information about how those rocks formed and what other regions of the US contain rocks similar in age. Brief descriptions of the geologic history for each region is provided. Educational levels: General public