Portal:North America/Selected picture/19
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![Geology of North America](http://upload.wikimedia.org/wikipedia/commons/thumb/1/1e/North_america_terrain_2003_map.jpg/425px-North_america_terrain_2003_map.jpg)
Relief map showing the varying age of bedrock underlying North America. This cartographic tapestry is woven from a geologic map and a shaded relief image. This combination reveals the geologic history of North America through the interrelation of rock type, topography and time. Regional surface processes as well as continent-scale tectonic events are exposed in the three dimensions of space and the fourth dimension, geologic time.