The Bishop Tuff refers to the deposits of ash and pumice ejected during the enormous eruption that created Long Valley Caldera.
Scientists estimate that more than 100 km3 (24 mi3) of tephra was dispersed widely as ashfall, and as much as about 200 km3 (48 mi3) erupted as pyroclastic flows/ignimbrite that flowed outside the caldera. Approximately 350 km3 (85 mi3) ponded and welded together within the caldera. Outside the caldera, these pyroclastic flows swept over an area of more than 2,200 km2 and buried the pre-existing ground to depths of nearly 200 m (660 f) just south of the caldera. These pyroclastic flow deposits show various degrees of welding.