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 1)

• The geologic history of Virginia is now understood in terms of the Wilson Cycle of plate tectonics, and begins about 1100 million years ago.

• The rocks of Virginia record one complete Wilson Cycle and parts of a second cycle. Virginia has been part of two supercontinents (Rodinia and Pangaea) and has been (or is) on the margins two oceans (Iapetus and Atlantic). 

1. 1100 million years ago

2. 750 to 560 million years ago

3. 560 million years ago

4. 560 to 480 million years ago

5. 480 to 250 million years ago

6. 250 million years ago

7. 225 to 200 million years ago

8. 200 million years ago to present

 

1100 Million Years Ago

• The oldest rocks in Virginia formed by a continent-continent collision called the Grenville orogeny. This formed a supercontinent called Rodinia. The formation of a supercontinent marks the end of a previous Wilson Cycle.

• 1100 year-old rocks are now found in the Blue Ridge and Piedmont as highly deformed igneous and metamorphic basement rocks.

Old Rag Mountain, Madison County, is in the Blue Ridge Province. The Blue Ridge contains most of the oldest rocks in Virginia that formed during the Grenville Orogeny. (Photograph by Stan Johnson)

The Old Rag Granite is one of the oldest rocks in Virginia, at 1.1 billion years old.  This granite can be found on top of Old Rag Mountain, shown here, in Madison County.

 

 

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