Long Valley Caldera is a volcanic caldera in eastern California that is adjacent to Mammoth Mountain. The valley is one of the Earth's largest calderas, measuring about 20 miles long, 11 miles wide, a
View from northeast rim of caldera
Layers of the Bishop tuff, in a rock quarry in Chalfant Valley, about 25 km (16 mi) southwest of the Long Valley Caldera, laid down in phases of a major eruption 760,000 years ago.