Mt. St. Helens/Toutle River Valley

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The debris avalanche traveled 14 miles down the Toutle River valley in the 1980 eruption, filling the valley to an average depth of 150 feet and leaving mounds of sediment in a bumpy pattern of hummocks (photo by Charlie Crisafulli).
The debris avalanche traveled 14 miles down the Toutle River valley in the 1980 eruption, filling the valley to an average depth of 150 feet and leaving mounds of sediment in a bumpy pattern of hummocks (photo by Charlie Crisafulli).