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Redondo Peak is an example of the volcanic feature known as a resurgent dome. It was formed shortly after the caldera-forming eruption of 1.25 million years ago, but it is not itself an eruptive feature. The summit of the mountain is composed of tuff ejected by the caldera-forming eruption, rather than of subsequent volcanic ejecta. [4]
In geology, a resurgent dome is a dome formed by swelling or rising of a caldera floor due to movement in the magma chamber beneath it. Unlike a lava dome , a resurgent dome is not formed by the extrusion of highly viscous lava onto the surface, but rather by the uplift and deformation of the surface itself by magma movement underground.
Caldera is the type locality for a resurgent dome caldera, the formation of which was first developed by C.S. Ross, R.L. Smith, and R.A. Bailey during field work at Valles in the 1960s. [19] This type locality and associated studies have been used to studied other resurgent domes around the world, including Yellowstone Caldera.
Map of Long Valley Caldera Early winter in Long Valley, 2017. Long Valley Caldera is a depression in eastern California that is adjacent to Mammoth Mountain.The valley is one of the Earth's largest calderas, measuring about 20 mi (32 km) long (east-west), 11 mi (18 km) wide (north-south), and up to 3,000 ft (910 m) deep.
Although the Valles caldera is not unusually large, it is relatively young (1.25 million years old) and unusually well preserved, [31] and it remains one of the best studied examples of a resurgent caldera. [6] The ash flow tuffs of the Valles caldera, such as the Bandelier Tuff, were among the first to be thoroughly characterized. [32]
After the formation of the caldera, sediments and [14] tuffs within the caldera were uplifted [15] over an angular area of 350 square kilometres (140 sq mi), forming the 1 kilometre (0.62 mi) high resurgent dome known as Cordón La Pacana. [16] This resurgent dome is cut by numerous faults and features a poorly developed graben on its summit. [14]
An estimated 400 acres of the caldera floor was covered in lava by 5:30 a.m., according to the Hawaiian Volcano Observatory. About four hours later, around 6:30 a.m. local time, the eruption had ...
Batu Gantung (Hanging stone) in Lake Toba Map of the lake. The Toba Caldera in North Sumatra comprises four overlapping volcanic craters that adjoin the Sumatran "volcanic front". At 100 by 30 kilometres (62 by 19 mi) it is the world's largest Quaternary caldera, and the fourth and youngest caldera. It intersects the three older calderas.