Editing Long Valley Caldera (section)

=== Eruptions ===
[[File:Long Valley Caldera cross section.gif|thumb|upright=1.15|Cross-section through Long Valley]]

Subsequent eruptions from the Long Valley magma chamber were confined within the caldera with extrusions of relatively hot (crystal-free) rhyolite 700,000 to 600,000 years ago as the caldera floor was uplifted to form the resurgent dome followed by extrusions of cooler, crystal-rich moat rhyolite at 200,000-year intervals (500,000, 300,000, and 100,000 years ago) in clockwise succession around the dome.<ref name=volcanoworld/> The declining volcanic activity and increasingly crystalline lava extruded over the last 650,000 years, as well as other trends, suggest that the magma reservoir under the caldera has now largely crystallized and is unlikely to produce large-scale eruptions in the future.<ref name="Hildreth">{{Cite journal | title=Volcanological perspectives on Long Valley, Mammoth Mountain, and Mono Craters: several contiguous but discrete systems|journal=[[Journal of Volcanology and Geothermal Research]] | last=Hildreth | first=Wes | date=25 September 2004 | volume=136 | issue=3–4 | doi=10.1016/j.jvolgeores.2004.05.019 | bibcode=2004JVGR..136..169H | pages=169–198 }}</ref>

The Long Valley volcano is unusual in that it has produced eruptions of both [[Lava#Mafic lava|basaltic]] and [[Lava#Felsic lava|silicic]] lava in the same geological place.<ref>{{cite journal | last=Johnson | first=B. F. | title=Supervolcano's different lavas hint at its decline | journal=Earth Magazine | date=June 2010 | pages=22–23}}</ref>

Water from the [[Owens River]] filled the caldera to a depth of {{convert|300|m|0|sp=us}} as of 600,000 years ago. At that time, the lake surface was at an elevation near {{convert|7500|ft|m}}.<ref>{{cite book |title= Geologic guidebook to the Long Valley—Mono Craters region of eastern California |first=S. R. |last= Lipshie |year=1976 |publisher= University of California |page= 27}}</ref> The lake drained sometime in the last 100,000 years after it overtopped the southern rim of the caldera, eroded the sill, and created the [[Owens River Gorge]]. A human-made dam in the gorge has created [[Lake Crowley|Crowley Lake]], a partial restoration of the original lake. Since the great eruption, many [[hot spring]]s developed in the area, and the resurgent dome has uplifted.

During the last [[ice age]], glaciers filled the canyons leading to Long Valley, but the valley floor was clear of ice. Excellent examples of [[terminal moraine]]s can be seen at Long Valley. Laurel Creek, [[Convict Creek]], and [[McGee Creek, California|McGee Creek]] each have prominent moraines.