Lava Creek Tuff

About

The Lava Creek Tuff is a voluminous sheet of ash-flow tuff located in Wyoming, Montana and Idaho, United States. It was created during the Lava Creek eruption around 640,000 years ago, which led to the formation of the Yellowstone Caldera. This eruption is considered the climactic event of Yellowstone's third volcanic cycle. The Lava Creek Tuff covers an area of more than 7,500 km2 (2,900 mi2) centered around the caldera and has an estimated magma volume of 1,000 km3 (240 cu mi).

The fallout from the eruption blanketed much of North America, depositing as one of the most widespread air-fall pyroclastic layers, formerly known as the Pearlette type O ash bed in the United States and Wascana Creek ash in Canada.