Skip to main content
U.S. flag

An official website of the United States government

Stratified 275-m (900-ft) thick mid-Holocene pyroclastic flow and l...

1905 (approx.)

Detailed Description

Visible relief in the hillside exposure is about 800-900 ft. Dusty assemblage deposit occurred approximately between 5100 and 5500 yr B.P. Magma volume of >5 km3, which is a lot for what was probably one eruptive stage. The source lava dome is gone, apparently having disintegrated entirely during extrusion and subsequent glacial interaction. Beige rocks in the foreground slope are hydrothermally altered deposits of the Pleistocene Gamma Ridge Formation, that is probably fill within a small caldera that preceded modern Glacier Peak. The skyline peak on the left is Tenpeak Mountain (Cretaceous granite), and Glacier Peak lies out of view to the upper right


Public Domain.