Join geology professor Shawn Willsey as he takes you on a tour of the Henrys Fork Caldera, a ~20-mile wide caldera that formed 1.3 million years ago during a huge violent eruption that ejected 280 cubic miles of ash. This eruption was the second most recent of the three big Yellowstone eruptions over the last two million years.

00:00 caldera locations
00:20 intro, within the caldera
01:55 map of Yellowstone's three recent calderas (from my book, Roadside Geology of Idaho)
04:08 generalized model of Yellowstone caldera eruptions (also from same book)
09:25 tour of Henrys Fork caldera rim
11:15 intracaldera basalt flow
13:41 Mesa Falls Tuff along caldera flank (just outside caldera)

You can order SIGNED copies of my books that cover this area: Geology Underfoot in Southern Idaho (a whole chapter on this area) and Roadside Geology of Idaho. Purchase here: https://shawn-willsey.square.site/

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Shawn Willsey
College of Southern Idaho
315 Falls Avenue
Twin Falls, ID 83303