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 7)

225 to 200 Million Years Ago

• Pangaea began to rift apart as a new Wilson Cycle began about 225 million years ago.

Reconstruction of the world 200 million years ago. By 200 million years ago, Pangaea had begun to rift apart, creating the rift basins found in eastern Virginia. (Image courtesy of the United States Geological Survey)

• As the continent stretched and broke, rift basins formed in eastern Virginia.  These basins filled with volcanic and continental sedimentary rocks.

• Rocks from this time are preserved in the Mesozoic Basins, where sedimentary and igneous rocks can be found.

Sedimentary conglomerate (left) and igneous diabase (right) are common rocks in the Mesozoic Basins. (Photographs by Stan Johnson)

Mudcracked sedimentary rocks from Virginia's Mesozoic Basins. Dinosaur footprints characteristic of this time period can be found in similar rocks in the Culpeper area. (Photograph by Robert Whisonant)

Rift basins are identified by their sedimentary rocks, igneous rocks, and lake beds.  The pictures above show a conglomerate (sedimentary), a diabase (igneous intrusion), and mud cracks in sandstone that indicate a drying lake bed.  These kinds of rocks can be found in Virginia’s Mesozoic Basins.

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