Mud on the Move

Volcanically active Mount Rainier has produced thick flows of mud from its sides and summit along with lava and ash. One of the largest mudflows occurred about 5,800 years ago, sending thick rivers of mud down the White River drainage. These flows carried rock and huge boulders, some 35 feet tall and several hundred feet around, from the mountain’s slopes to the surrounding lowlands. The Osceola mudflow, the largest of the mountain’s historic flows, covered about 100 square miles and buried the present town site of Enumclaw, 24 miles west of here, under as much as 70 feet of debris. Seismic activity triggered the mudflow, causing the collapse of nearly 2,000 feet of Mount Rainier’s summit.

Washington · United States