Aerial view of Toney Mountain from the east.
|Elevation||3,595 m (11,795 ft)|
|Prominence||1,946 m (6,385 ft)|
|Location||Marie Byrd Land, Antarctica|
|Age of rock||Quaternary|
|Mountain type||Shield volcano|
|Volcanic field||Marie Byrd Land Volcanic Province|
Toney Mountain is an elongated snow-covered shield volcano, 60 km (37 mi) long and rising to 3,595 m (11,795 ft) at Richmond Peak, located 56 km (35 mi) southwest of Kohler Range in Marie Byrd Land, Antarctica.
Toney Mountain is an elongated volcanic massif that rises from a basaltic lava plateau. 3 km (1.9 mi) wide summit caldera tops the volcano, and is elongated in east-west direction; this orientation is shared with calderas on other volcanoes in Marie Byrd Land and reflects regional tectonic stress. The slopes of the volcano feature parasitic vents and glacial corries, and are much steeper north of the volcano than south of it. Most of the mountain is covered by ice and its eastern sector may be a crater. That the mountain is mostly ice covered makes it difficult to determine its composition, the origin of the elongated shape of the volcano and the volcanological relation between the parasitic cinder cones and the main volcanic pile. Its volume may be about 2,800 km3 (670 cu mi).A
The plateau and parasitic cones are formed by hawaiite and the few outcrops on the main volcano by benmoreite and comendite. They contain phenocrysts of olivine, plagioclase, pyroxene and titanaugite in the former and of clinopyroxene, feldspar and olivine.
An age of 9.1 million years ago has been obtained on a basaltic lava flow beneath the volcano,and it has been inferred that the basal plateau formed between 10.1 and 9.1 million years ago. The massif is younger, with ages ranging from 1 million years in its lower parts to 500,000 years ago. Holocene eruptions may have also occurred at Toney Mountain as indicated by 30 kyr ash layers in ice cores from Byrd Station, although Mount Takahe and Mount Waesche are also candidates. During that time period, a number of volcanic eruptions occurred in Antarctica as recorded by ash layers in ice; this coincides with the coldest period of the Wisconsin glaciation and it is possible that the effects of ash clouds from the Antarctic eruptions caused this period of cold global temperatures. On the other hand, it is also possible that growing ice sheets during this period compressed magma chambers and thus triggered explosive eruptions.
Toney Mountain lies in Marie Byrd Land, a tectonically and volcanically active region of Antarctica. There, a layer of basaltic rocks up to 5 km (3.1 mi) thick underlie a series of felsic volcanic edifices. These basaltic rocks in turn are emplaced above a Paleozoic basement with granite intrusions of Devonian-Cretaceous, which crops out in some mountain ranges. Beneath Toney Mountain, the basaltic floor rises from an elevation of 3 km (1.9 mi) beneath sea level, and the volcano is situated on the floor of a graben. The region is further characterized by a 500 km × 1,200 km (310 mi × 750 mi) large dome-like uplift, part of the West Antarctic Rift System, and it may reflect the presence of a stationary hotspot.
Toney Mountain was probably among those viewed from a distance by Admiral Byrd and others of the USAS in plane flights from the ship Bear in February 1940. It was mapped in December 1957 by the oversnow traverse party from Byrd Station to the Sentinel Range, 1957–58, led by C.R. Bentley who proposed the name. Named after George R. Toney, scientific leader at Byrd Station in 1957, a participant in several Antarctic and Arctic operations, serving in both field and administrative capacities.
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 million km2.
Marie Byrd Land is the portion of West Antarctica lying east of the Ross Ice Shelf and the Ross Sea and south of the Pacific Ocean, extending eastward approximately to a line between the head of the Ross Ice Shelf and Eights Coast. It stretches between 158°W and 103°24'W. The inclusion of the area between the Rockefeller Plateau and Eights Coast is based upon the leading role of the American Rear Admiral Richard E. Byrd in the exploration of this area. The name was originally applied by Admiral Byrd in 1929, in honor of his wife, to the northwestern part of the area, the part that was explored in that year.
The Hudson Mountains are a mountain range in western Ellsworth Land just east of Cranton Bay and Pine Island Bay at the eastern extremity of 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.
Mount Frakes is a prominent shield volcano marking the highest elevation in the Crary Mountains, in Marie Byrd Land, Antarctica and is the third highest volcanic elevation on the continent.
Mount Hampton 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. However, there is also evidence of recent fumarolic activity.
Mount Melbourne is a 2,733-metre-high (8,967 ft) ice-covered stratovolcano in Victoria Land, Antarctica, between the 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 CE. The volcano is considered inactive.
Mount Morning is a shield volcano at the foot of the Transantarctic Mountains in Victoria Land, Antarctica. It lies 100 kilometres (62 mi) from Ross Island. Mount Morning rises to an elevation of 2,723 metres (8,934 ft) and is almost entirely mantled with snow and ice. A 4.1 by 4.9 kilometres wide summit caldera lies at the top of the volcano and several ice-free ridges such as Hurricane Ridge and Riviera Ridge emanate from the summit. A number of parasitic vents mainly in the form of cinder cones dot the mountain.
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 Murphy is a massive, snow-covered and highly eroded shield volcano in Marie Byrd Land of West Antarctica with steep, rocky slopes. It is directly south of Bear Peninsula and is bounded by the Smith, Pope and Haynes Glaciers. Volcanic activity began in the Miocene with the eruption of basaltic and trachytic lava. Volcanism on the slopes of the volcano resumed much later during the Pleistocene, with a parasitic cone having been K–Ar dated to 0.9 million years old.
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 stratovolcano 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.
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.
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.
Several types of volcanic eruptions—during which lava, tephra, and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior has been observed. Some volcanoes may exhibit only one characteristic type of eruption during a period of activity, while others may display an entire sequence of types all in one eruptive series.
Sollipulli is an ice-filled volcanic caldera and volcanic complex, which lies southeast of the small town of Melipeuco in the La Araucanía Region, Chile. It is part of the Southern Volcanic Zone of the Andes, one of the four volcanic belts in the Andes chain.
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; 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 3,478 metres (11,411 ft) high glacier-covered volcano in Marie Byrd Land, Antarctica, 210 kilometres (130 mi) from the Amundsen Sea. It is a c. 20-kilometre-wide (12 mi) mountain with parasitic vents that consists of two coalesced volcanoes; Berlin proper with the 2 kilometres (1.2 mi) wide Berlin Crater and Merrem Peak with a 2.5 by 1 kilometre wide crater, 3.5 kilometres (2.2 mi) away from Berlin. Trachyte is the dominant volcanic rock and occurs in the form of lava flows and pyroclastic rocks. It has a volume of 2,000 km3 (500 cu mi) and rises from the West Antarctic Ice Sheet. It is part of the Marie Byrd Land Volcanic Province.