Editing Long Valley Caldera (section)

{{Short description|Landform near Mammoth Mountain, California, USA}}
{{Infobox valley
| name = Long Valley Caldera
| photo = Long Valley caldera NE rim.jpg
| photo_caption = View from northeast rim of caldera
| location = [[Mono County, California]]<br />United States
| elevation = {{convert|6500|-|8500|ft|m|-2|abbr=on}}
|coordinates = {{coord|37|43|00|N|118|53|03|W|type:landmark|format=dms|display=inline,title}}
| coordinates_ref = <ref>{{cite gnis|id=274650|name=Long Valley Caldera}}</ref>
| length = {{convert|20|mi|km|0|abbr=on}}
| direction = EW
| width = {{convert|11|mi|km|0|abbr=on}}
| depth = up to {{convert|3000|ft|m|-2|abbr=on}}
| type = [[Caldera]]
| age = 760,000 yrs
}}
[[File:CalderaRelief large.png|thumb|upright=1.15|Map of Long Valley Caldera]]
[[File:Long Valley early winter 2017.jpg|thumb|upright=1.15|Early winter in Long Valley, 2017]]
'''Long Valley Caldera''' is a [[Depression (geology)|depression]] in [[eastern California]] that is adjacent to [[Mammoth Mountain]]. The valley is one of the Earth's largest [[caldera]]s, measuring about {{convert|20|mi}} long (east-west), {{convert|11|mi}} wide (north-south), and up to {{convert|3000|ft}} deep.

Long Valley was formed 760,000 years ago when a [[Ultra-Plinian|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 flow]]s that burned and buried thousands of square miles. Ash from this eruption blanketed much of the [[Western United States|western part]] of what is now the [[United States]].