Long Valley Caldera

Long Valley Caldera
View from northeast rim of caldera
Floor elevation6,500–8,500 ft (2,000–2,600 m)
Length20 mi (32 km) EW
Width11 mi (18 km)
Depthup to 3,000 ft (900 m)
Geology
TypeCaldera
Age760,000 yrs
Geography
LocationMono County, California
United States
Coordinates37°43′00″N 118°53′03″W / 37.71667°N 118.88417°W / 37.71667; -118.88417[1]
Map of Long Valley Caldera
Early winter in Long Valley, 2017

Long Valley Caldera is a depression in eastern California that is adjacent to Mammoth Mountain. The valley is one of the Earth's largest calderas, measuring about 20 mi (32 km) long (east-west), 11 mi (18 km) wide (north-south), and up to 3,000 ft (910 m) deep.

Long Valley was formed 760,000 years ago when a very large eruption released hot ash that later cooled to form the Bishop tuff that is common to the area. The eruption emptied the magma chamber under the area to the point of collapse. The second phase of the eruption released pyroclastic flows that burned and buried thousands of square miles. Ash from this eruption blanketed much of the western part of what is now the United States.

  1. ^ "Long Valley Caldera". Geographic Names Information System. United States Geological Survey, United States Department of the Interior.