Lava Creek Tuff

Lava Creek Tuff is a vast sheet of welded volcanic ash centered on Yellowstone and spread across parts of Wyoming, Montana, and Idaho. It formed about 630,000 to 640,000 years ago during the eruption that created the Yellowstone Caldera and climaxed Yellowstone’s third volcanic cycle. Covering more than 7,500 square kilometers and representing about 1,000 cubic kilometers of magma, it records an eruption whose ash blanketed much of North America. In Yellowstone, exposures at places such as Tuff Cliff, Virginia Cascade, and along U.S. Highway 20 provide clear evidence of this caldera-forming event. Its layered ash flows and mineral studies also reveal a complex, multi-stage eruption from separate magma reservoirs.

Wyoming · United States