The wax and wane of volcanism over 3.5 m.y. in the Goat Rocks Wilderness area, Washington Cascade Range

Kellie Wall

U.S. Geological Survey  

Near and within the Goat Rocks Wilderness in Washington state, between Mount Rainier and Mount Adams, lie the remnants of several volcanoes that were active between ~3.6 million years ago and ~60 thousand years ago. Gutted by recent glaciation, the volcanic stratigraphy is laid bare for exploration by geologists and hikers alike. From an early explosive rhyolite eruption to mafic shield volcanoes to composite volcanoes that erupted some of the world’s longest andesite lava flows, these volcanoes spanned a wide range of magma compositions and eruption styles. Using geochronology and chemical compositions of the volcanic rocks and minerals, we reconstruct the eruptive timeline and investigate magma sources, storage conditions, and pre-eruptive magmatic processes—building toward a 4D view of how a major volcanic locus builds, evolves, and ends.

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In the Hop Mahal Room

5:30 pm social hour

7:00 pm presentation

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