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Geologic Map
Shaded Relief
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Generalized Geologic Map of the Conterminous United States
North America Shaded Relief


  The North American Tapestry of Time and Terrain

The Two Maps
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Legend and Rock Ages
Rock Types
Political Boundaries

  The Two Maps: Geology and Shaded Relief Map

Link to Geologic map  Link to Shaded Relief map
Click either map for a larger image: Geology or Shaded Relief maps.

Through digital mapping and GIS (geographic information systems) technology, we have drawn together information from two different types of maps into a single digital tapestry. Embedded within this map are a geologic map of North America, compiled by John C. Reed of the U.S. Geological Survey and John O. Wheeler of the Geological Survey of Canada, and a shaded relief map, which was created by converting elevation data into a digitally-shaded map of the North American landscape.

This geologic map has been simplified from its original source map, in order to show patterns of rock age and distribution, and then reprojected to match the shaded relief map for a perfect image overlay. The resulting composite displays both the land surface and the ages of its underlying rock formations. This digital tapestry outlines the geologic story of continental collision and break-up, mountain-building, river erosion and sediment deposition, ice-cap glaciation, volcanism, and other events and processes that have shaped the continent over the last 4 billion years.