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


  The North American Tapestry of Time and Terrain

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Legend and Rock Ages
Rock Types
Political Boundaries

  Legend and Rock Ages

Silurian Rocks - 440 to 410 million years ago

map of Silurian rocks


The Silurian is a relatively brief period on the time scale. During the Silurian, collisions between early continents that included parts of modern North America, Africa, and Europe formed long mountain chains. The earliest evidence of complex life on land, in the form of small plants and animals such as centipedes, is found in Silurian rocks, as well.

Modern features that have Silurian rocks include the Appalachian Valley and Ridge Province, the northeast's exotic terranes, and the Finger Lakes region.