Volcano Type: Caldera
Volcano Status: Pleistocene-Fumarolic
Last Known Eruption: Pleistocene
Summit Elevation: 3390 m 11,122 feet
Latitude: 37.70°N 37°42’0″N
Longitude: 118.87°W 118°52’0″W
Long Valley caldera, located at the boundary between the Sierra Nevada and the Basin and Range Province, is one of the largest Quaternary rhyolitic volcanic centers in North America. The caldera is elliptical in shape and 10 by 20 miles (15 by 30 km) in size. 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).
Long Valley (Obsidian Flow)
The large 17 x 32 km Long Valley caldera east of the central Sierra Nevada Range formed as a result of the voluminous Bishop Tuff eruption about 760,000 years ago. Resurgent doming in the central part of the caldera occurred shortly afterwards, followed by rhyolitic eruptions from the caldera moat and the eruption of rhyodacite from outer ring fracture vents, ending about 50,000 years ago. During early resurgent doming the caldera was filled with a large lake that left strandlines on the caldera walls and the resurgent dome island; the lake eventually drained through the Owens River Gorge. The caldera remains thermally active, with many hot springs and fumaroles, and has had significant deformation, seismicity, and other unrest in recent years. The late-Pleistocene to Holocene Inyo Craters cut the NW topographic rim of the caldera, and along with Mammoth Mountain on the SW topographic rim, are west of the structural caldera and are chemically and tectonically distinct from the Long Valley magmatic system.
Upwelling in Hot Creek
Little Hot Creek
Originally posted 2010-08-16 08:24:40.
