Thursday, March 02, 2006

Magma On The Move Beneath Yellowstone

Much of Yellowstone National Park is a giant collapsed volcano, or a caldera. In an enormous eruption roughly 640,000 years ago, this volcano spit out around 240 cubic miles of rock, dirt, magma and other material. Around 70,000 years ago its last eruption filled in that gaping hole with flows of lava. The area has enjoyed an uneasy peace since then, the land alternately rising and falling with the passing decades. New satellite data indicate that this uplift and subsidence is caused by the movement of magma beneath the surface and may explain why the northern edge of the park continues to rise while the southern part of the caldera is falling.

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