Collision of The Intermontane Islands
Over early Jurassic time, the Intermontane Islands and the Pacific Northwest drew closer together as the continent moved west and the Intermontane Microplate subducted. On the continent, subduction supported a new volcanic arc that again sent intruding granite-type rocks into the ancient continental sediments. Eventually, about 180 million years ago in the middle Jurassic, the last of the microplate subducted, and the Intermontane Islands collided with the Pacific Northwest.
The Intermontane Islands were too big to sink beneath the continent. The subduction zone of the Intermontane Plate shut down, ending the volcanic arc. As the Intermontane Belt accreted to the edge of the continent, the subduction zone of the Insular Plate became the active subduction zone along the edge of the continent.
Read more about this topic: Intermontane Plate
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“I know my fate. One day my name will be tied to the memory of something monstrous—a crisis without equal on earth, the most profound collision of conscience, a decision invoked against everything that had previously been believed, demanded, sanctified. I am no man, I am dynamite!”
—Friedrich Nietzsche (1844–1900)
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