A view from the Sediment Retention Structure at Mount St. Helens Photos by Cheryl Landes On May 18, 1980, when Mount St. Helens erupted, the blast deposited more than three billion cubic yards of sediment into the Toutle River Basin, covering 32 miles with an average depth of 150 feet. Mudflows filled the Cowlitz River … Continue reading Armchair photo tours: The Sediment Retention Structure at Mount St. Helens
Armchair photo tours: The Sediment Retention Structure at Mount St. Helens
