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Astrid Ridge
Astrid Ridge is an undersea ridge on the continental margin of Dronning Maud Land, East Antarctica. It is present on the GEBCO 5th edition charts. The name was approved by the Advisory Committee for Undersea Features in June 1987. The ocean along the continental margin of Dronning Maud Land, the Riiser-Larsen and Lazarev seas, are dominated by three topographic features: Astrid Ridge, Maud Rise, a large volcanic plateau in the Lazarev Sea (3°E, 65°S), and Gunnerus Ridge (33.5°E), probably underlain by continental crust. Astrid Ridge, extending from 65°S to the Antarctic margin and located between 9°E and 17°E, forms the eastern border of the Lazarev Sea and the western border of the Riiser-Larsen Sea. It is divided into two parts by the Astrid Fracture Zone: south of 67°S Astrid Ridge stretches N-S while the northern part follows the SW—NE direction of the fracture zone. The geological evolution of the Astrid Ridge remains enigmatic. The Riiser-Larsen Sea is a c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Undersea Ridge
A mid-ocean ridge (MOR) is a seafloor mountain system formed by plate tectonics. It typically has a depth of about and rises about above the deepest portion of an ocean basin. This feature is where seafloor spreading takes place along a divergent plate boundary. The rate of seafloor spreading determines the morphology of the crest of the mid-ocean ridge and its width in an ocean basin. The production of new seafloor and oceanic lithosphere results from mantle upwelling in response to plate separation. The melt rises as magma at the linear weakness between the separating plates, and emerges as lava, creating new oceanic crust and lithosphere upon cooling. The first discovered mid-ocean ridge was the Mid-Atlantic Ridge, which is a spreading center that bisects the North and South Atlantic basins; hence the origin of the name 'mid-ocean ridge'. Most oceanic spreading centers are not in the middle of their hosting ocean basis but regardless, are traditionally called mid-ocean ri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dronning Maud Land
Queen Maud Land ( no, Dronning Maud Land) is a roughly region of Antarctica claimed by Norway as a dependent territory. It borders the claimed British Antarctic Territory 20° west and the Australian Antarctic Territory 45° east. In addition, a small unclaimed area from 1939 was annexed in June 2015. Positioned in East Antarctica, it makes out about one-fifth of the continent, and is named after the Norwegian queen Maud of Wales (1869–1938). In 1930, the Norwegian Hjalmar Riiser-Larsen was the first person known to have set foot in the territory. On 14 January 1939, the territory was claimed by Norway. On 23 June 1961, Queen Maud Land became part of the Antarctic Treaty System, making it a demilitarised zone. It is one of two Antarctic claims made by Norway, the other being Peter I Island. They are administered by the Polar Affairs Department of the Norwegian Ministry of Justice and Public Security in Oslo. Most of the territory is covered by the east Anta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
East Antarctica
East Antarctica, also called Greater Antarctica, constitutes the majority (two-thirds) of the Antarctic continent, lying on the Indian Ocean side of the continent, separated from West Antarctica by the Transantarctic Mountains. It lies almost entirely within the Eastern Hemisphere and its name has been accepted for more than a century. It is generally higher than West Antarctica and includes the Gamburtsev Mountain Range in the center. The geographic South Pole is located within East Antarctica. Apart from small areas of the coast, East Antarctica is permanently covered by ice and it has relatively low biodiversity, with only a small number of species of terrestrial plants, animals, algae, and lichens. The coasts are the breeding ground for various seabirds and penguins, and the leopard seal, Weddell seal, elephant seal, crabeater seal and Ross seal breed on the surrounding pack ice in summer. Location and description Almost completely covered in thick, permanent i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GEBCO
The General Bathymetric Chart of the Oceans (GEBCO) is a publicly available bathymetric chart of the world's oceans. The project was conceived with the aim of preparing a global series of charts showing the general shape of the seafloor. Over the years it has become a reference map of the bathymetry of the world’s oceans for scientists and others. Organisation GEBCO operates under the joint auspices of the International Hydrographic Organization (IHO). and the Intergovernmental Oceanographic Commission (IOC) of UNESCO. Its work is done by an international group of experts in seafloor mapping who develop a range of bathymetric data sets and data products. Data sets and products Although originally GEBCO published paper contour charts, today it has moved into the digital age and collects digital depths of the ocean from wherever they are available. GEBCO provides a range of bathymetric data sets and data products, including: *Global gridded bathymetric data sets: **GEBCO_08 G ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Advisory Committee For Undersea Features
The United States Board on Geographic Names (BGN) is a federal body operating under the United States Secretary of the Interior. The purpose of the board is to establish and maintain uniform usage of geographic names throughout the federal government of the United States. History On January 8, 1890, Thomas Corwin Mendenhall, superintendent of the US Coast and Geodetic Survey Office, wrote to 10 noted geographers "to suggest the organization of a Board made up of representatives from the different Government services interested, to which may be referred any disputed question of geographical orthography." President Benjamin Harrison signed executive order 28 on September 4, 1890, establishing the ''Board on Geographical Names''. "To this Board shall be referred all unsettled questions concerning geographic names. The decisions of the Board are to be accepted y federal departmentsas the standard authority for such matters." The board was given authority to resolve all unsettled quest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Riiser-Larsen Sea
The Riiser-Larsen Sea is one of the marginal seas located in the Southern Ocean off East Antarctica and south of the Indian Ocean. It is delimited Astrid Ridge in the west and the Gunnerus Ridge and the Kainanmaru Bank in the east. It is bordered by the Lazarev Sea to the west and the Cosmonauts Sea to the east, or between 14°E and 30°E. Its northern border is defined to be the 65th parallel south. The name, proposed by the Soviet Union, was never officially approved by the International Hydrographic Organization (IHO). To the south of this area lies the Princess Astrid Coast and Princess Ragnhild Coast of Queen Maud Land. In the western part is the Lazarev Ice Shelf, and further east are Erskine Iceport and Godel Iceport, and the former Belgian Roi-Baudouin Station. Name dispute The Riiser-Larsen Sea was named in 1962 by the Soviet Antarctic Expedition in honor of Norwegian aviation pioneer and polar explorer Hjalmar Riiser-Larsen (1890–1965). The IHO 2002 draft was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lazarev Sea
The Lazarev Sea (, ''More Lazareva'') is a proposed name for a marginal sea of the Southern Ocean. It would be bordered by two proposals from a 2002 International Hydrographic Organization (IHO) draft, a King Haakon VII Sea to the west and a Riiser-Larsen Sea to the east, or between the Prime Meridian of 0° and 14°E. It would stretch over an area of . History The Lazarev Sea was named in 1962 by the Soviet Antarctic Expedition in memory of Russian admiral Mikhail Lazarev (1788–1851), who discovered the Antarctic mainland with Fabian Gottlieb von Bellingshausen in 1820. The 2002 IHO draft was never approved by the IHO (or any other organization), and the 1953 IHO document (which does not contain this name) remains currently in force. Leading geographic authorities and atlases do not use the name, including the 2014 10th edition World Atlas from National Geographic Society and the 2014 12th edition of the Times Atlas of the World. But Soviet and Russian-state maps do. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maud Rise
Maud Rise () is an oceanic plateau, which rises, at its shallowest, to depths of about a 1,000 meters. It is located in the Weddell Sea in the Southern Ocean. Its name was approved by the Advisory Committee for Undersea Features in June 1987. Geology Maud Rise formed part of the south-eastern African large igneous province (LIP) which developed south of Africa (Ma). This LIP first formed 140-122 Ma east of South Africa where the Mozambique Ridge is now located. There it reached a maximum extent around 120 Ma when the African-Antarctic spreading zone was located below its eastern flank. Astrid Ridge was possibly part of this LIP as well. The LIP formation then continued intermittently until it finally reached its maximum extent south of South Africa 100 Ma. This volcanism ended 94 Ma after which sea-floor spreading divided the LIP into the Agulhas Plateau (south of South Africa), Northeast Georgia Rise (near South Georgia Island off South America), and Maud Rise. See al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gunnerus Ridge
Johan Ernst Gunnerus (26 February 1718 – 25 September 1773) was a Norwegian bishop and botanist. Gunnerus was born at Christiania. He was bishop of the Diocese of Nidaros from 1758 until his death and also a professor of theology at the University of Copenhagen. Biography Gunnerus was born and raised in Christiania in Norway. He enrolled at the University of Copenhagen in Denmark in 1737, but had to postpone his studies for three years because of poverty. He studied in Copenhagen from 1740, at Halle in Germany from 1742, and at Jena from 1744, where he received his Magister degree in 1745 and in 1753 was admitted to the Faculty of Philosophy. At Jena he published extensively, notably a work on natural and international law in eight volumes. In 1754 he was recalled to Denmark and appointed Professor and Rector at Herlufsholm. In 1758 he became Bishop of the Diocese of Nidaros in Trondheim, Norway. Gunnerus was very interested in natural history and accumulated a large col ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Continental Crust
Continental crust is the layer of igneous, sedimentary, and metamorphic rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called '' sial'' because its bulk composition is richer in aluminium silicates (Al-Si) and has a lower density compared to the oceanic crust, called ''sima'' which is richer in magnesium silicate (Mg-Si) minerals. Changes in seismic wave velocities have shown that at a certain depth (the Conrad discontinuity), there is a reasonably sharp contrast between the more felsic upper continental crust and the lower continental crust, which is more mafic in character. The continental crust consists of various layers, with a bulk composition that is intermediate (SiO2 wt% = 60.6). The average density of continental crust is about , less dense than the ultramafic material that makes up the mantle, which has a density of around . Continental crust is also less dense ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mozambique Basin
Mozambique (), officially the Republic of Mozambique ( pt, Moçambique or , ; ny, Mozambiki; sw, Msumbiji; ts, Muzambhiki), is a country located in southeastern Africa bordered by the Indian Ocean to the east, Tanzania to the north, Malawi and Zambia to the northwest, Zimbabwe to the west, and Eswatini and South Africa to the southwest. The sovereign state is separated from the Comoros, Mayotte and Madagascar by the Mozambique Channel to the east. The capital and largest city is Maputo. Notably Northern Mozambique lies within the monsoon trade winds of the Indian Ocean and is frequentely affected by disruptive weather. Between the 7th and 11th centuries, a series of Swahili port towns developed on that area, which contributed to the development of a distinct Swahili culture and language. In the late medieval period, these towns were frequented by traders from Somalia, Ethiopia, Egypt, Arabia, Persia, and India. The voyage of Vasco da Gama in 1498 marked the arrival of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gondwana
Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages of break-up, involving the separation of Antarctica from South America (forming the Drake Passage) and Australia, occurred during the Paleogene. Gondwana was not considered a supercontinent by the earliest definition, since the landmasses of Baltica, Laurentia, and Siberia were separated from it. To differentiate it from the Indian region of the same name (see ), it is also commonly called Gondwanaland. Gondwana was formed by the accretion of several cratons. Eventually, Gondwana became the largest piece of continental crust of the Palaeozoic Era, covering an area of about , about one-fifth of the Earth's surface. During the Carboniferous Period, it merged with Laurasia to form a larger supercontinent called Pangaea. Gondwana ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
