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View north along U.S. Route 20 from near Ashton, ID, at the margin of the Huckleberry Ridge Tuff in the distance

Detailed Description

Google maps photo taken just north of Ashton, ID, along U.S. Route 20. The photo was taken looking north towards Island Park, ID. The forested ridge in the distance marks the margin of a caldera that formed 2.08 million years ago, when the Huckleberry Ridge Tuff erupted. The hill labeled as the Rhyolite of Snake Butte is the only known pre-caldera rhyolite lava flow, at 2.14 million years old.


Public Domain.