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Mount Takahe
Mount Takahe is a snow-covered shield volcano in Marie Byrd Land, Antarctica, from the Amundsen Sea. It is a mountain with parasitic vents and a caldera up to 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 , 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. The volcano was active in the Quaternary period, from 2.5 million years ago to the present. Radiometric dating has yielded ages of up to 300,000years for its rocks, and it reached its present height about 200,000years ago. Several tephra layers encountered in ice cores at Mount Waesche and Byrd Station have been attributed to Mount Takahe, although some of them were later linked to eruptions of Mount Berlin instead. The tephra laye ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antarctica
Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest continent, being about 40% larger than Europe, and has an area of . Most of Antarctica is covered by the Antarctic ice sheet, with an average thickness of . Antarctica is, on average, the coldest, driest, and windiest of the continents, and it has the highest average elevation. It is mainly a polar desert, with annual precipitation of over along the coast and far less inland. About 70% of the world's freshwater reserves are frozen in Antarctica, which, if melted, would raise global sea levels by almost . Antarctica holds the record for the lowest measured temperature on Earth, . The coastal regions can reach temperatures over in summer. Native species of animals include mites, nematodes, penguins, seals and tardigrades. Where vegetation o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ice Core
An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier. Since the ice forms from the incremental buildup of annual layers of snow, lower layers are older than upper ones, and an ice core contains ice formed over a range of years. Cores are drilled with hand augers (for shallow holes) or powered drills; they can reach depths of over two miles (3.2 km), and contain ice up to 800,000 years old. The physical properties of the ice and of material trapped in it can be used to reconstruct the climate over the age range of the core. The proportions of different oxygen and hydrogen isotopes provide information about ancient temperatures, and the air trapped in tiny bubbles can be analysed to determine the level of atmospheric gases such as carbon dioxide. Since heat flow in a large ice sheet is very slow, the borehole temperature is another indicator of temperature in the past. These data can be combined to find the climate model ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antarctic Station
Multiple governments have set up permanent research stations in Antarctica and these bases are widely distributed. Unlike the drifting ice stations set up in the Arctic, the research stations of the Antarctic are constructed either on rock or on ice that is (for practical purposes) fixed in place. Many of the stations are staffed throughout the year. A total of 42 countries (as of October 2006), all signatories to the Antarctic Treaty, operate seasonal (summer) and year-round research stations on the continent. The population of people performing and supporting scientific research on the continent and nearby islands varies from approximately 4,000 during the summer season to 1,000 during winter (June). In addition to these permanent stations, approximately 30 field camps are established each summer to support specific projects. History First bases During the Heroic Age of Antarctic Exploration in the late 19th century, the first bases on the continent were established. I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Route
The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing for liquid water to exist on the Earth's surface, absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night (the diurnal temperature variation). By mole fraction (i.e., by number of molecules), dry air contains 78.08% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapor, on average around 1% at sea level, and 0.4% over the entire atmosphere. Air composition, temperature, and atmospheric pressure vary with altitude. Within the atmosphere, air suitable for use in photosynthesis by terrestrial plants and breathing of terrestrial animals is found only in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Toney Mountain
Toney Mountain is an elongated snow-covered shield volcano, long and rising to at Richmond Peak, located southwest of Kohler Range in Marie Byrd Land, Antarctica. Toney Mountain is an elongated volcanic massif that rises from a basaltic lava plateau. A 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 . The plateau and parasitic cones are formed by hawaiite and the few out ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mount Murphy
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. Delineated from aerial photographs taken by US Navy Operation Highjump in January 1947. Named by US-ACAN for Robert Cushman Murphy of the American Museum of Natural History, noted authority on Antarctic and sub-Antarctic bird life. While serving on the whaler, he charted the Bay of Isles region of South Georgia. Features Bucher Peak () at , is one of the highest peaks in the west-central summit area of the Mount Murphy massif. Buettner Peak is a sharp peak rising midway along the north wall of Roos Glacier ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bear Peninsula
Bear Peninsula () is a peninsula about 80 km (50 mi) long and 40 km (25 mi) wide which is ice covered except for several isolated rock bluffs and outcrops along its margins, lying 48 km 30 mi) east of Martin Peninsula on Walgreen Coast, Marie Byrd Land, Antarctica. First delineated from aerial photographs taken by USN Operation Highjump in January 1947. Named by the Advisory Committee on Antarctic Names (US-ACAN) after the ice-ship ''USS Bear'', flagship of the USAS, from which three reconnaissance flights were made in late February 1940, resulting in the discovery of Walgreen Coast (with probable sighting of this feature) and the Thurston Island area. This ship, under the name Bear of Oakland, also served as flagship of the Byrd AE, 1933–35, which based at the Bay of Whales, Ross Ice Shelf. Launched in 1874 at Greenock, Scotland, for use in the sealing trade, she sank in 30-foot seas and high winds in the North Atlantic, March 19, 1963, at which tim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bakutis Coast
The Bakutis Coast is that part of the coast of Marie Byrd Land, West Antarctica, extending from a point opposite eastern Dean Island, at , to Cape Herlacher, or between Hobbs Coast in the west and Walgreen Coast in the east. It stretches between 127°05'W and 114°12'W. The coast in this area is bounded by several large ice-covered islands and the very extensive Getz Ice Shelf. This coast was sighted by members of the US Antarctic Service, 1939–1941, and was charted in part from air photos taken by Operation Highjump, 1946–1947, both expeditions led by Admiral Richard E. Byrd. The United States Geological Survey completely mapped the coast from ground surveys and U.S. Navy air photos, 1959–1966. Bakutis Coast was named by the Advisory Committee on Antarctic Names for Rear Admiral Fred E. Bakutis, Commander of the U.S. Naval Support Force, Antarctica, from 1965 to 1967. The hinterland of Bakutis Coast is the location of Byrd Station, which is located in the interior, abo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holocene
The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene together form the Quaternary period. The Holocene has been identified with the current warm period, known as MIS 1. It is considered by some to be an interglacial period within the Pleistocene Epoch, called the Flandrian interglacial.Oxford University Press – Why Geography Matters: More Than Ever (book) – "Holocene Humanity" section https://books.google.com/books?id=7P0_sWIcBNsC The Holocene corresponds with the rapid proliferation, growth and impacts of the human species worldwide, including all of its written history, technological revolutions, development of major civilizations, and overall significant transition towards urban living in the present. The human impact on modern-era Earth and its ecosystems may be considered of global si ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ozone Hole
Ozone depletion consists of two related events observed since the late 1970s: a steady lowering of about four percent in the total amount of ozone in Earth's atmosphere, and a much larger springtime decrease in stratospheric ozone (the ozone layer) around Earth's polar regions. The latter phenomenon is referred to as the ozone hole. There are also springtime polar tropospheric ozone depletion events in addition to these stratospheric events. The main causes of ozone depletion and the ozone hole are manufactured chemicals, especially manufactured halocarbon refrigerants, solvents, propellants, and foam-blowing agents (chlorofluorocarbons (CFCs), HCFCs, halons), referred to as ozone-depleting substances (ODS). These compounds are transported into the stratosphere by turbulent mixing after being emitted from the surface, mixing much faster than the molecules can settle. Once in the stratosphere, they release atoms from the halogen group through photodissociation, which catalyze t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phreatomagmatic
Phreatomagmatic eruptions are volcanic eruptions resulting from interaction between magma and water. They differ from exclusively magmatic eruptions and phreatic eruptions. Unlike phreatic eruptions, the products of phreatomagmatic eruptions contain juvenile (magmatic) clasts.Heiken, G. & Wohletz, K. 1985. Volcanic Ash. University of California Press, Berkeley It is common for a large explosive eruption to have magmatic and phreatomagmatic components. Mechanisms Several competing theories exist as to the exact mechanism of ash formation. The most common is the theory of explosive thermal contraction of particles under rapid cooling from contact with water. In many cases the water is supplied by the sea, for example with Surtsey. In other cases the water may be present in a lake or caldera-lake, for example Santorini, where the phreatomagmatic component of the Minoan eruption was a result of both a lake and later the sea. There have also been examples of interaction between magma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Explosive Eruption
In volcanology, an explosive eruption is a volcanic eruption of the most violent type. A notable example is the 1980 eruption of Mount St. Helens. Such eruptions result when sufficient gas has dissolved under pressure within a viscous magma such that expelled lava violently froths into volcanic ash when pressure is suddenly lowered at the vent. Sometimes a lava plug will block the conduit to the summit, and when this occurs, eruptions are more violent. Explosive eruptions can expel as much as per second of rocks, dust, gas and pyroclastic material, averaged over the duration of eruption, that travels at several hundred meters per second as high as into the atmosphere. This cloud may subsequently collapse, creating a fast-moving pyroclastic flow of hot volcanic matter. Stages of an explosive eruption An explosive eruption begins with some form of blockage in the crater of a volcano that prevents the release of gases trapped in highly viscous andesitic or rhyolitic magma. The pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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