During the middle Mesozoic, Pangaea began to rotate, but the different components of the huge mass rotated at different rates and then in different directions -- rifts began to form. The first of these was a southwestward tear on the mouth. It opened as the southern part of theNorth Atlantic Ocean and continued westward into the Gulf of Mexico. The Cordilleran arc was now firmly established along the Pacific margin of North and South America.

The great supercontinent begins to fracture and the central Atlantic and Gulf of Mexico are born. A great arc is built on western N. A. and the Nevadan orogeny begins. Cimmeria begins its collision with Laurasia to form the Cimmerian orogeny.

Paleogeographic globes

  • 170 Ma

    Tectonics, Sedimentation, Paleogeography of North Atlantic Region

  • 200 Ma
  • 170 Ma
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    1st Order Global Tectonic Features

  • 200 Ma
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  • 150 Ma
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