Lava Creek Tuff

Lava Creek Tuff
Tuff Cliff showing the Lava Creek Tuff formation
Volcano	Yellowstone Caldera
Date	Around 630,000 years ago
Type	Ignimbrite-forming
Location	Wyoming, United States 44°24′N 110°42′W / 44.400°N 110.700°W / 44.400; -110.700
Volume	>1,000 km3 (240 cu mi)
VEI	8
Extent of the Lava Creek ash bed

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 630,000 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 sq mi) 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.

The thick tuff formation resulting from this eruption is well-exposed at various locations within Yellowstone National Park, including Tuff Cliff along the Gibbon River, Virginia Cascade, and along U.S. Highway 20.

Lava Creek Tuff ranges in color from light gray to pale red in some locales. Rock texture of the tuff ranges from fine-grained to aphanitic and is densely welded. The maximum thickness of the tuff layer is approximately 180–200 m (590–660 ft).^[1]