How is the Grand Canyon related to volcanic activity?

In the western Grand Canyon hundreds of volcanic eruptions occurred over the past two million years. At least a dozen times, lava cascaded down the walls of the Inner Gorge, forming massive lava dams that blocked the flow of the Colorado River. ... 1064 a series of eruptions built the park's namesake cinder cone.

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c. heat from the poles back down towards the equator.