Pyroclastic Flow Outcrop on the Pumice Plain at Mount St. Helens

This photo shows an outcrop of pyroclastic flow deposits near Willow Creek on the Pumice Plain at Mount St. Helens. The dramatic lines crossing the outcrop indicate contacts between different layers of pyroclastic flow deposits. Two participants of the 2019 GeoGirls program are shown studying the outcrop, using it to understand the eruptive history of the volcano. GeoGirls is an educational program involving middle school girls, high school and local teacher mentors, and volunteer scientists that is jointly run by the Mount St. Helens Institute and the U.S. Geological Survey.