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The mountain system dominates the Eastern United States and seperates the Eastern seaboard from the interior with a belt of uplands that extends nearly 1,500 miles from northeastern Alabama to the Canadian border.; They are old, complex mountains, eroded from muc ....

Middle of Essay
.... in the Shenandoah National Park. In late Precambrian time this super continent began to rift apart under the tensional forces producing the Catoctin rift basalts that can be observed in the Shenandoah. As they rifted apart, they created a growing ocean called the proto-Atlantic or Iapetus after the father of Atlas, for whom the Atlantic Ocean is named. Towards the end of the Precambrian, the tensional forces changed to compression and subduction began. Volcanic islands grew as a result of andesitic volcanism associated with the subduction. With continued subduction and convergence, volcanic islands collided with North America and those rocks w ....