Glacier Peak

About Glacier Peak

Glacier Peak, the most isolated of the Cascade volcanoes, rises above the rugged forested terrain of the Glacier Peak Wilderness Area in the North Cascades. This dacitic-andesitic stratovolcano with summit and flank lava domes resembles St. Helens in its explosive vigor. More than a dozen glaciers descend its flanks, prompting its name. Although its summit towers above surrounding valleys, the volcano was constructed above a high ridge and is itself less than 1,000 m high. Repeated major explosive eruptions associated with lava dome growth during the late Pleistocene and Holocene deposited tephra over wide distances to the east. Voluminous pyroclastic flows and mudflows extended into the Puget Sound lowlands to the west and diverted several river courses into adjacent valleys. The latest eruption only a few hundred years ago was noted by indigenous Pacific Northwest Indians, and hot springs occur on its flanks.