Long Valley Caldera is a depression in eastern California that is adjacent to Mammoth Mountain. The valley is one of the largest calderas on earth, measuring about 32 kilometres long (east-west) and 17 kilometres wide (north-south). The elevation of the floor of the caldera is 6,500 feet (2,000 m) in the east and 8,500 feet (2600 m) in the west. The elevation of the walls of the caldera reach elevations of 9,800-11,500 feet (3000-3500 m) except in the east where the wall rises only 500 feet (150 m) to an elevation of 7,550 feet (2,300 m). Image File history File links USGS image from [1] File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Eastern California is not a well-defined term. ... Mammoth Mountain is a volcano that lies to the west of the town of Mammoth Lakes, California in the Inyo National Forest. ... Crater Lake, Oregon A caldera is a volcanic feature formed by the collapse of a volcano into itself. ... Earth, also known as Terra, and (mostly in the 19th century) Tellus, is the third-closest planet to the Sun. ...

Long Valley was formed 760,000 years ago when a huge volcanic eruption released very hot ash that later cooled to form the Bishop tuff that is common to the area. The eruption was so colossal that the magma chamber under the now completely destroyed volcano was significantly emptied to the point of collapse. The collapse itself caused an even larger secondary eruption of pyroclastic ash 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. Geologists call topographic depressions formed in this manner calderas. Eruption redirects here. ... The Bishop Tuff is located in the Owens Valley, southeast of Mammoth Lakes, California. ... A magma chamber is the chamber beneath a volcano where the magma is held before an eruption. ... Pyroclastic rocks are formed from lavas which are ejected into the air, as occur in pyroclastic flows or Plinian eruptions. ... Crater Lake, Oregon A caldera is a volcanic feature formed by the collapse of a volcano into itself. ...

Near the center of the caldera there is a mound called the "resurgent dome" that was formed by magmatic uplift. The area is still volcanically active and has periodic rhyolitic lava flows. There is a hydrothermal power plant near the resurgent dome. The Bishop tuff is the oldest normally magnetized tuff (that is, it was formed when the earth's magnetic north was near the north pole - as it is today). In the geologic past, water gathered in the Long Valley caldera and overtopped its rim forming the Owens River Gorge. Magma is molten rock often located inside a magma chamber beneath the surface of the Earth. ... Rhyolite Rhyolite is an igneous, volcanic (extrusive) rock, of felsic composition, with aphanitic to porphyritic texture. ... Look up Lava, ‘A‘a, or Pāhoehoe in Wiktionary, the free dictionary Lava is molten rock that a volcano expels during an eruption. ... Hydrothermal circulation in the oceans is the passage of the water through mid-ocean Ridge (MOR) systems. ... This is about the geographic meaning of North Pole. ... Owens Valley The Owens River is a river in eastern California in the United States, approximately 120 mi (193 km) long. ...

Mammoth Mountain (11,050 feet), is a composite volcano made up of about 12 rhyodacite and quartz latite domes extruded along the southwest rim of Long Valley Caldera from 200,000 to 50,000 years ago. Mammoth Mountain is one of the eruptive centers that developed late in the evolutionary cycle of the Long Valley Caldera complex. View of Mount Rainier, a stratovolcano. ... BOOOOOOOOYAAAAAAAA!!!!!!!!!!! ... A quartz latite is a latite with a phenocryst modal composition containing 5-20% quartz. ...

The history and deposits of the Mono and Inyo Craters overlap with Long Valley Caldera in time and space. The Mono-Inyo Craters volcanic field developed along a 30-mile-long (50 km) fissure system that extends northward from Mammoth Mountain on the southwestern rim of the caldera to Mono Lake. One of the Mono craters: an excellent example of a rhyolite dome. ... Mono Lake, showing nearby Lake Tahoe and Yosemite National Park Mono Lake is an alkaline and hypersaline lake in California, United States that is a critical nesting habitat for several bird species and is one of the most productive ecosystems in North America. ...

Hot Creek. Same view in winter

Hot Creek (shown in the image to the left) has cut into the floor of the caldera and passes through hot springs. The warm water of Hot Creek supports many trout, and is used at the Hot Creek Fish Hatchery. Hot Creek is part of a stream that follows part of a fault line and is well-known for its hydrothermal pools and for the contrast swimmers experience between the cold stream water and either the occasional plume of very hot water (which can burn swimmer's feet and can on rare occasions cause more serious injury) or even long and very strong upwellings of hot water when enough water is in the hydrothermal system ( photo). Download high resolution version (1200x900, 179 KB)Image taken in September 2003 by Daniel Mayer. ... Download high resolution version (1200x900, 179 KB)Image taken in September 2003 by Daniel Mayer. ... Image taken in April 2003 by Daniel Mayer. ... Long Valley Caldera hosts an active hydrothermal system that includes hot springs, fumaroles (steam vents), and mineral deposits. ... Old fault exposed by roadcut near Harrisburg, Pennsylvania. ... Hydrothermal circulation in the oceans is the passage of the water through mid-ocean Ridge (MOR) systems. ... Image taken in September 2003 by Daniel Mayer. ...

Over a dozen people have died in Hot Creek since the late 1960s but most of these deaths happened to individuals who ignored the numerous warning signs and attempted to use the hydrothermal pools as hot tubs (like the stream portion of the creek, these pools alternate in temperature but the eruptions in the pools are of super-heated water in already very hot water). Hot tub in a Canadian ski resort A hot tub is a large tub or small pool full of heated water and used for soaking, relaxation, hydrotherapy, reading, or meditation. ...

Detailed geology

The known volcanic history of the Long Valley area started several million years ago when magma began to collect several miles below the surface. Volcanic activity became concentrated in the vicinity of the present site of Long Valley Caldera 3.1 to 2.5 million years ago with eruptions of rhyodacite followed by high-silica rhyolite from 2.1 to 0.8 million years ago. After some time a cluster of mostly rhyolitic volcanoes formed in the area. All told, the about 1,500 square miles (4,000 square kilometers) were covered by lava. Eruption redirects here. ... Magma is molten rock often located inside a magma chamber beneath the surface of the Earth. ... BOOOOOOOOYAAAAAAAA!!!!!!!!!!! ... Rhyolite Rhyolite is an igneous, volcanic (extrusive) rock, of felsic composition, with aphanitic to porphyritic texture. ...

All but one of these volcanoes, 1-2 million year old Glass Mountain (made of obsidian), was completely destroyed by the major eruption of the area 760,000 years ago, which released 600 cubic kilometres of material from vents just inside the margin of the caldera (the 1980 Mount St. Helens eruption was 1.2 km³). About half of this material was ejected in a series of pyroclastic flows of a very hot (1,500 degree Fahrenheit or 800 degree Celsius) mixture of noxious gas, pumice, and ash that covered the surrounding area hundreds of feet deep. One lobe of this material moved south into Owens Valley, past where Big Pine, California now lies. Another lobe moved west over the crest of the Sierra Nevada and into the drainage of the San Joaquin River. The rest of the pyroclastic material along with 300 km³ of other matter, was blown as far as 25 miles (40 km) into the air where winds distributed it as far away as eastern Nebraska and Kansas. However, much of the material ejected straight into the air fell back to earth to fill the 2 to 3 km deep caldera two-thirds to its rim. Image File history File links Public domain USGS image from http://volcano. ... Obsidian from Lake County, Oregon Top stone is obsidian, below that is pumice and in lower right hand is rhyolite (light color) Obsidian is a type of naturally occurring glass, produced from volcanoes when a fluid felsic lava cools rapidly and freezes without sufficient time for crystal growth, for example... A cubic kilometre (symbol km³) is an SI derived unit of volume. ... (Redirected from 1980 Mount St. ... Pyroclastic flows sweep down the flanks of Mayon Volcano, Philippines, in 1984 Pyroclastic flows are a common and devastating result of some volcanic eruptions. ... A gas is one of the four main phases of matter (after solid and liquid, and followed by plasma), that subsequently appear as a solid material is subjected to increasingly higher temperatures. ... Specimen of highly porous pumice from Teide volcano on Tenerife, Canary Islands. ... Diamond Head, a well-known backdrop to Waikiki in Hawaii, is an ash cone that solidified into tuff Volcanic ash is the term for very fine rock and mineral particles less than 2 mm in diameter that are ejected from a volcanic vent. ... Owens Valley is the arid ranching valley of the Owens River in southeastern California in the United States. ... Big Pine is a census-designated place located in Inyo County, California. ... The Sierra Nevada is a mountain range that is almost entirely in eastern California. ... The San Joaquin River is one of the largest rivers in the state of California. ... Wind is the quasi-horizontal movement of air (as opposed to an air current) caused by uneven heating of the Earths surface. ... State nickname: Cornhusker State Official languages English Capital Lincoln Largest city Omaha Governor Dave Heineman (R) Senators Chuck Hagel (R) Ben Nelson (D) Area  - Total  - % water Ranked 16th 200,520 km² 0. ... State nickname: The Sunflower State Official languages None Capital Topeka Largest city Wichita Governor Kathleen Sebelius (D) Senators Sam Brownback (R) Pat Roberts (R) Area  - Total  - % water Ranked 15th 82,277 mi²; 213,096 km² 0. ...

Hot Creek Fish Hatchery at base of Resurgent Dome

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 upwarped 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 resurgent dome. Download high resolution version (1200x512, 75 KB)Image taken in September 2003 by Daniel Mayer. ... Download high resolution version (1200x512, 75 KB)Image taken in September 2003 by Daniel Mayer. ...

At its height 600,000 years ago, an Owens River-fed 300 foot deep lake filled the caldera and rose to an elevation of 7,800 feet (2,400 m) above sea level. The lake was completely 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 dam in the gorge has partially restored part of that lake which is now known as Lake Crowley. Since the great eruption many hot springs developed in the area and the resurgent dome has uplifted. Owens Valley The Owens River is a river in eastern California in the United States, approximately 120 mi (193 km) long. ... Lake Crowley is a reservoir on the upper Owens River in southern Mono County, California in the United States. ... Green Dragon Spring at Norris Geyser A hot spring is a place where warm or hot groundwater issues from the ground on a regular basis for at least a predictable part of the year, and is significantly above the ambient ground temperature (which is usually around 55~57 F or...

Notable geothermal areas in Long Valley include; Casa Diablo at the base of resurgent dome and Hot Creek which is about 5 miles (8 km) from Casa Diablo and cuts into part of resurgent dome. Hydrothermal activity has altered many rocks in the caldera transforming them into travertine and clay. The Huntley clay mine is exposed on resurgent dome and appears as a brilliant white band. A white chalky clay called kaolinite is mined here. Long Valley Caldera hosts an active hydrothermal system that includes hot springs, fumaroles (steam vents), and mineral deposits. ... Travertine A carving in travertine Travertine, a natural stone, is a white concretionary form of calcium carbonate that is usually hard and semicrystalline. ... Quaternary clay in Estonia. ... Kaolin Kaolinite (Aluminium Silicate Hydroxide) Kaolinite is a mineral with the chemical composition Al2Si2O5(OH)4. ...

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 moraines can be seen at Long Valley: these moraines are the debris left from glacial sculpting. Laurel Creek, Convict Creek, and McGee Creek all have prominent moraines. Moraine is the general term for debris of all sorts originally transported by glaciers or ice sheets that have since melted away. ...

In May of 1980, a strong earthquake swarm that included four Richter magnitude 6 earthquakes struck the southern margin of Long Valley Caldera associated with a 25-cm, dome-shaped uplift of the caldera floor. These events marked the onset of the latest period of caldera unrest that continues to this day. This ongoing unrest includes recurring earthquake swarms and continued dome-shaped uplift of the central section of the caldera (the resurgent dome) accompanied by changes in thermal springs and gas emissions. After the quake another road was created as an escape route. Its name at first was proposed as the "Mammoth Escape Route" but was changed to the Mammoth Scenic Route after Mammoth area businesses and land owners complained. 1980 (MCMLXXX) was a leap year starting on Tuesday. ... Global earthquake epicenters, 1963–1998 An earthquake is a sudden and sometimes catastrophic movement of a part of the Earths surface. ... The Richter magnitude test scale (or more correctly local magnitude ML scale) assigns a single number to quantify the size of an earthquake. ...

In 1982, the United States Geological Survey under the Volcano Hazards Program began an intensive effort to monitor and study geologic unrest in Long Valley Caldera. The goal of this effort is to provide residents and civil authorities in the area reliable information on the nature of the potential hazards posed by this unrest and timely warning of an impending volcanic eruption, should it develop. Most, perhaps all, volcanic eruptions are preceded and accompanied by geophysical and geochemical changes in the volcanic system. Common precursory indicators of volcanic activity include increased seismicity, ground deformation, and variations in the nature and rate of gas emissions. 1982 (MCMLXXXII) is a common year starting on Friday of the Gregorian calendar. ... The United States Geological Survey (USGS) is a scientific agency of the United States government. ... The Volcano Hazards Program is a program directed by the USGS that monitors the activity of volcanoes and the public awareness of eruptions. ...

Alternate figure of Long Valley Caldera cross-section

See also: Mono-Inyo Craters, Map of Long Valley-Mono area This image is not an orphan—see Long Valley Caldera This image is linked from a text link only, or for some other reason, is needed but still appears to have nothing linking to it. ... This image is not an orphan—see Long Valley Caldera This image is linked from a text link only, or for some other reason, is needed but still appears to have nothing linking to it. ... One of the Mono craters: an excellent example of a rhyolite dome. ... Download high resolution version (600x668, 115 KB) [1] This image is not an orphan—see Long Valley Caldera This image is needed as it is either linked from a text link or is otherwise useful, even though it appears to have nothing linking to it. ...

References

• Roadside Geology of Northern and Central California, Alt, Hyndman (Mountain Press Publishing Company, Missoula; 2000) ISBN 0-87842-409-1
• Geology Underfoot in Death Valley and Owens Valley, Sharp, Glazner (Mountain Press Publishing Company, Missoula; 1997) ISBN 0-87842-362-1
• USGS Volcano Hazards Program: Long Valley Observatory (public domain text)

See also: List of guidebooks about the Sierra Nevada Below is a list of guidebooks about the Sierra Nevada of California, USA. Please see Sierra Nevada for more information. ...