Insular plate

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Plate tectonics along the west coast of North America 130 million years ago Insular Omineca arcs.png
Plate tectonics along the west coast of North America 130 million years ago

The Insular Plate was an ancient oceanic plate that began subducting under the west-coast of North America around the early Cretaceous period. The Insular Plate had a chain of active volcanic islands that were called the Insular Islands. These volcanic islands, however, collided then fused onto the west-coast of North America when the Insular Plate jammed then shut down ending the subduction zone. [1]

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References

  1. Townsend, Catherine L.; Figge, John T. (2002). "The Coast Range Episode". Northwest Origins: An Introduction to the Geologic History of Washington State. The Burke Museum of Natural History and Culture, University of Washington. Retrieved 12 August 2019.