Mount Hampton | |
---|---|
Highest point | |
Elevation | 3,323 m (10,902 ft) |
Coordinates | 76°29′0″S125°48′0″W / 76.48333°S 125.80000°W [1] |
Geography | |
Parent range | Executive Committee Range |
Geology | |
Mountain type | Shield volcano |
Volcanic field | Marie Byrd Land Volcanic Province |
Mount Hampton [lower-alpha 1] is a shield volcano with a circular ice-filled caldera. It is a twin volcano with Whitney Peak to the northwest and has erupted phonolite rocks. It is the northernmost of the volcanoes which comprise the Executive Committee Range in Marie Byrd Land, Antarctica and was active during the Miocene.
Mount Hampton is the northernmost volcano of the Executive Committee Range in Marie Byrd Land, Antarctica. It has the form of a symmetrical uneroded shield volcano [4] with an "impressive" appearance and an ice-filled [5] 6.5 by 5.5 kilometres (4.0 mi × 3.4 mi) wide caldera. [6] Like other volcanoes in the Executive Committee Range, it is a paired volcano [7] with the northwesterly 3,003 metres (9,852 ft) high Whitney Peak and the southeasterly 3,323 metres (10,902 ft) high Marks Peak, which is the main summit of Mount Hampton. [8] [lower-alpha 2] The northwesterly summit is associated with its own caldera, which is partly cut by the Mount Hampton caldera on the southeastern flank and buried by the lava flows from the latter. [10] The centres of the two calderas are about 8 kilometres (5.0 mi) apart. [11] Based on outcrops, it appears that most of the volcano is formed by flow rocks [12] but cinder and lava bombs occur at parasitic vents. [13]
The mountain rises about 1 kilometre (0.62 mi) above the surface of the West Antarctic Ice Sheet [14] which buries most of the edifice, and moraine ridges are found at its base on the ice sheet. [15] Owing to climate conditions, the persistence of permanent ice atop of the mountain is unlikely over the long term; [16] erosion there appears to have been episodic [17] with maxima during interglacials [18] and there is no evidence of cirque formation. [19] Lichens have been found on the mountain. [20]
The volcano is formed by phonolite rocks, but parasitic vents have also erupted basanite [21] and Whitney Peak also erupted trachyte and benmoreite. [22] Hawaiite has been reported as well. [23] The volcanic rocks contain augite and feldspar; further, spinel-containing lherzolite xenoliths have been found. [24] In general, composition is unique for each volcano in the Executive Committee Range. [25]
Mount Hampton is one of the oldest volcanoes of Antarctica and was active during the Miocene. [26] Despite this, it is less eroded than some younger volcanoes in the region; [27] in general, the ages of the Marie Byrd Land volcanoes are not correlated to their erosion status. [28] It appears that Whitney Peak is the older half of the edifice and that volcanic activity then migrated to Mount Hampton. [29] More generally, volcanism in the Executive Committee Range migrated southwards over time at an average rate of 0.7 centimetres per year (0.28 in/year), although Mount Hampton and its southern neighbour Mount Cumming were simultaneously active 10 million years ago. [30]
Last parasitic eruptions took place around 11.4 million years ago [31] and the youngest radiometric dates are 8.3 million years. [32] As at other volcanoes of Marie Byrd Land, the parasitic activity at Mount Hampton occurred after a long period of dormancy. [33] However, the presence around the caldera rim of snow-covered [34] inactive 10–20 metres (33–66 ft) high ice towers [lower-alpha 3] indicate that the mountain is geothermally active [37] and may have erupted during the Holocene. [38] Later research suggested that the ice towers were actually formed by wind-driven erosion of snow and ice. There is no evidence of geothermal processes [39] and seismic activity recorded at the volcano may be due to volcano-tectonic processes or due to ice movement. [40]
The geography of Antarctica is dominated by its south polar location and, thus, by ice. The Antarctic continent, located in the Earth's southern hemisphere, is centered asymmetrically around the South Pole and largely south of the Antarctic Circle. It is washed by the Southern Ocean or, depending on definition, the southern Pacific, Atlantic, and Indian Oceans. It has an area of more than 14.2 million km2. Antarctica is the largest ice desert in the world.
Marie Byrd Land (MBL) is an unclaimed region of Antarctica. With an area of 1,610,000 km2 (620,000 sq mi), it is the largest unclaimed territory on Earth. It was named after the wife of American naval officer Richard E. Byrd, who explored the region in the early 20th century.
Mount Andrus is a peak 2 nautical miles southeast of Mount Boennighausen in the southeast extremity of the Ames Range, in Marie Byrd Land, Antarctica.
Gaussberg is an extinct, 370-metre-high (1,210-foot) high volcanic cone in East Antarctica fronting on Davis Sea immediately west of Posadowsky Glacier. It is ice-free and conical in nature, having formed subglacially about 55,000 years ago. The current edifice is thought to be the remains of a once-larger mountain that has been reduced by glacial and subaerial erosion. The volcano has produced lamproite magmas, and is the youngest volcano to have produced such magmas on Earth.
Mount Melbourne is a 2,733-metre-high (8,967 ft) ice-covered stratovolcano in Victoria Land, Antarctica, between Wood Bay and Terra Nova Bay. It is an elongated mountain with a summit caldera filled with ice with numerous parasitic vents; a volcanic field surrounds the edifice. Mount Melbourne has a volume of about 180 cubic kilometres (43 cu mi) and consists of tephra deposits and lava flows; tephra deposits are also found encased within ice and have been used to date the last eruption of Mount Melbourne to 1892 ± 30 years. The volcano is fumarolically active.
Mount Moulton is a 40-kilometre-long (25 mi) complex of ice-covered shield volcanoes, standing 25 kilometres (16 mi) east of Mount Berlin in the Flood Range, Marie Byrd Land, Antarctica. It is named for Richard S. Moulton, chief dog driver at West Base. The volcano is of Pliocene age and is presently inactive.
Mount Sidley is the highest dormant volcano in Antarctica, a member of the Volcanic Seven Summits, with a summit elevation of 4,181–4,285 metres (13,717–14,058 ft). It is a massive, mainly snow-covered shield volcano, which is the highest of the five volcanic mountains that comprise the Executive Committee Range of Marie Byrd Land. The feature is marked by a 5 km wide caldera on the southern side and stands NE of Mount Waesche in the southern part of the range.
Mount Takahe is a 3,460-metre-high (11,350 ft) snow-covered shield volcano in Marie Byrd Land, Antarctica, 200 kilometres (120 mi) from the Amundsen Sea. It is a c. 30-kilometre-wide (19 mi) mountain with parasitic vents and a caldera up to 8 kilometres (5 mi) wide. Most of the volcano is formed by trachytic lava flows, but hyaloclastite is also found. Snow, ice, and glaciers cover most of Mount Takahe. With a volume of 780 km3 (200 cu mi), it is a massive volcano; the parts of the edifice that are buried underneath the West Antarctic Ice Sheet are probably even larger. It is part of the West Antarctic Rift System along with eighteen other known volcanoes.
Toney Mountain is an elongated snow-covered shield volcano, 38 nautical miles long and rising to 3,595 metres (11,795 ft) at Richmond Peak, located 35 nautical miles southwest of Kohler Range in Marie Byrd Land, Antarctica.
Mount Waesche is a mountain of volcanic origin at the southern end of the Executive Committee Range in Marie Byrd Land, Antarctica. It is 3,292 metres high, and stands 20 kilometres southwest of Mount Sidley, the highest volcano in Antarctica. The mountain lies southwest of the Chang Peak caldera and is largely covered with snow and glaciers, but there are rock exposures on the southern and southwestern slopes.
Bridgeman Island is one of the South Shetland Islands in Antarctica. It is an almost circular, volcanic island marked by steep sides, measuring 900 by 600 metres with a maximum elevation of 240 m (787 ft) high, lying 45 kilometres (28 mi) east of King George Island.
The Pleiades are a volcanic group in northern Victoria Land of Antarctica. It consists of youthful cones and domes with Mount Atlas/Mount Pleiones, a small stratovolcano formed by three overlapping cones, being the dominant volcano and rising 500 m (1,600 ft) above the Evans Névé plateau. Two other named cones are Alcyone Cone and Taygete Cone, the latter of which has been radiometrically dated to have erupted during the Holocene. A number of tephra layers across Antarctica have been attributed to eruptions of this volcanic group, including several that may have occurred within the last few hundred years.
Crary Mountains are a group of ice-covered volcanoes in Marie Byrd Land, Antarctica. They consist of two or three shield volcanoes, named Mount Rees, Mount Steere and Mount Frakes, which developed during the course of the Miocene and Pliocene and last erupted about 30,000-40,000 years ago. The first two volcanoes are both heavily incised by cirques, while Mount Frakes is better preserved and has a 4 kilometres (2.5 mi) wide caldera at its summit. Boyd Ridge is another part of the mountain range and lies southeast of Mount Frakes; it might be the emergent part of a platform that underlies the mountain range.
Mount Siple is a potentially active Antarctic shield volcano, rising to 3,110 metres (10,203 ft) and dominating the northwest part of Siple Island, which is separated from the Bakutis Coast, Marie Byrd Land, by the Getz Ice Shelf. Its youthful appearance strongly suggests that it last erupted in the Holocene. It is capped by a 4-by-5-kilometre summit caldera, and tuff cones lie on the lower flanks. Recely Bluff is on the northeast slope of the mountain, about 7 nautical miles (13 km) from the peak. Its volume of 1,800 cubic kilometres (430 cu mi) is comparable to that of Mount Erebus.
Dorrel Rock is a nunatak located 20 km (12 mi) southwest of the summit of Mount Murphy, protruding through the ice near the head of Pope Glacier, on the Walgreen Coast, Marie Byrd Land. It was mapped by the United States Geological Survey from surveys and U.S. Navy air photos, 1959–66, and was named by the Advisory Committee on Antarctic Names after Leo E. Dorrel, U.S. Navy, a hospital corpsman with the Byrd Station winter party, 1966.
Mount Rittmann is a volcano in Antarctica. Discovered in 1988–1989 by an Italian expedition, it was named after the volcanologist Alfred Rittmann (1893–1980). It features a 2 kilometres (1.2 mi) or 8 by 5 kilometres wide caldera which crops out from underneath the Aviator Glacier. The volcano was active during the Pliocene and into the Holocene, including large explosive eruptions; a major eruption occurred in 1254 CE and deposited tephra over much of Antarctica. Currently, the volcano is classified as dormant.
The Marie Byrd Land Volcanic Province is a volcanic field in northern Marie Byrd Land of West Antarctica, consisting of over 18 large shield volcanoes, 30 small volcanic centres and possibly many more centres buried under the West Antarctic Ice Sheet. It overlies a 500 km (310 mi) wide and 800 km (500 mi) long dome that has formed as a result of fault blocking within the West Antarctic Rift System.
Mount Berlin is a glacier-covered volcano in Marie Byrd Land, Antarctica, 100 kilometres (62 mi) from the Amundsen Sea. It is a roughly 20-kilometre-wide (12 mi) mountain with parasitic vents that consists of two coalesced volcanoes: Berlin proper with the 2-kilometre-wide (1.2 mi) Berlin Crater and Merrem Peak with a 2.5-by-1-kilometre-wide crater, 3.5 kilometres (2.2 mi) away from Berlin. The summit of the volcano is 3,478 metres (11,411 ft) above sea level. It has a volume of 200 cubic kilometres (48 cu mi) and rises from the West Antarctic Ice Sheet. It is part of the Marie Byrd Land Volcanic Province. Trachyte is the dominant volcanic rock and occurs in the form of lava flows and pyroclastic rocks.
Mount Petras is a mountain in Antarctica. It consists of volcanic rocks, most of Cretaceous age but there is also an Eocene-Oligocene volcanic system that may have been emplaced inside of thin ice. It is part of the Marie Byrd Land Volcanic Province and is its oldest volcano.
The Hudson Mountains are a mountain range in western Ellsworth Land just east of Pine Island Bay at the Walgreen Coast of the Amundsen Sea. They are of volcanic origin, consisting of low scattered mountains and nunataks that protrude through the West Antarctic Ice Sheet. The Hudson Mountains are bounded on the north by Cosgrove Ice Shelf and on the south by Pine Island Glacier. The mountains were volcanically active during the Miocene and Pliocene, but there is evidence for an eruption about two millennia ago and uncertain indications of activity in the 20th century.