Long Valley Caldera
depression in California, United States
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 (32 km) long (east-west), 11 miles (18 km) wide (north-south), and up to 3,000 feet (910 m) deep.
The caldera 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.
Geography
The caldera is a giant bowl-shaped depression, approximately 20 miles (32 km) long, surrounded by mountains except to the southeast. The elevation of the bottom of the bowl ranges from 6,500 to 8,500 feet (2,000 to 2,600 m), being higher in the west.
Near the center of the bowl, magmatic uplift has formed a resurgent dome. The southeastern slope from the caldera down towards Bishop is filled with the Bishop Tuff, solidified ash that was ejected during the eruption that created the caldera.
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The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Aug 19, 2026. The linked authority identifier is Q143338. VIAF identifies the subject as 245874014. The Library of Congress control number is sh99013469. Authority coordinates are 37.717, -118.884. 3 of 3 selected statements include explicit references; 0 carry qualifiers and 0 use preferred rank.
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This entry incorporates text from “Long Valley Caldera” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.