The May 18, 1980 eruption of Mount St. Helens, a volcano located in state of Washington, was one of the most destructive events in the history of the United States. In just a matter of hours, the north face of the volcano collapsed creating a huge landslide - the largest debris avalanche in recorded history – that moved swiftly towards the surrounding lakes and the North Fork Toutle River valley leaving a trail of destruction 27 km long. Located only about 5 miles north-northeast of the volcanic  crater, Spirit Lake received the full impact of the lateral blast.

An estimated 1 million trees were blown away from the surrounding hillside by a super-heated wall of volcanic gas and searing ash and rock, and these along with other rubble were deposited on Spirit Lake. The debris avalanche temporarily displaced much of the lake from its bed sending 600-foot-high waves crashing into a ridge north of the lake. As the water moved back into its basin, it pulled with it thousands of more trees into the lake. About 350,000 acre-feet of pyrolized trees were deposited into Spirit Lake and these shattered trees formed a floating log raft on the lake surface that is present to this day, more than three decades after the event.

A portion of the thousands of trees that remain floating in a giant raft on the surface of the lake. Photo taken on March 29, 2007. Photo credit