Debris avalanche ponds 1980

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The debris avalanche obliterated forests and created hummocks and basins. Rock that used to be the north side of the volcano covered about 23 square miles, primarily in the North Fork Toutle River valley, leaving hummocks (mounds) and basins. The former forest was obliterated and buried under sand and rock from 33 to 640 feet thick.

Debris avalanche ponds 1980.