Plate Tectonics Topics

• Introduction
• Theory Development
• Principles of Plate Tectonics
• Plate Tectonics History of Virginia
  1. 1100 m.y.a.
  2. 750-560 m.y.a.
  3. 560 m.y.a.
  4. 560-480 m.y.a.
  5. 480-250 m.y.a.
  6. 250 m.y.a.
  7. 225-200 m.y.a.
  8. 200 m.y.a. to present

Plate Tectonics History of Virginia (Part 8)

200 Million Years Ago to Present

• The Atlantic Ocean opened and widened.

• A passive margin formed along eastern North America.

• A thick pile of sedimentary rock was deposited along the edge of the continent, forming the Coastal Plain.

Gravel deposits and a modern beach are part of the continental margin of the Atlantic Ocean as seen in Virginia's Coastal Plain. (Photographs by Robert Whisonant)

• Deposition in the Coastal Plain and seafloor spreading in the Atlantic Ocean continue today. Most Coastal Plain sediments, including the gravel shown here (above left), are younger than about 200 million years old.

• In the Piedmont, Blue Ridge, Valley and Ridge, and Appalachian Plateaus, stream and river erosion has shaped the land that we see today. The harder and more resistant rocks such as sandstone and granite form the mountains and ridges, while the softer and weaker rocks such as shale, limestone, and schist form the valleys. This has created the landscape that that is the familiar modern Appalachian Mountains.

End CD-1, Introduction and Geologic Background

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