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24-729: The Iceland Plateau is bounded on the south by the Reykjanes Ridge , on the west by the Greenland-Iceland Ridge, on the north by the Kolbeinsey Ridge , and on the east by the Iceland-Faeroe Ridge. It consists of a large igneous province that has been volcanically active since at least the Miocene epoch. The plateau has an average elevation of 1,700 meters above sea level. The geology of

48-701: A junction with the Gakkel Ridge (Mid-Arctic Ridge) northeast of Greenland southward to the Bouvet triple junction in the South Atlantic. Although the Mid-Atlantic Ridge is mostly an underwater feature, portions of it have enough elevation to extend above sea level, for example in Iceland . The ridge has an average spreading rate of about 2.5 centimetres (1 in) per year. A ridge under

72-404: A warm Mediterranean climate ( Köppen climate classification : Csb ). The climate is consistently mild, with no temperature or rainfall extremes. According to South African National Parks , who administer the nature reserve, the average rainfall is 400–600 mm per annum, mostly received in winter. Temperature climate data is available for Cape Agulhas, averages are: The sea off Cape Agulhas

96-792: Is a mid-ocean ridge (a divergent or constructive plate boundary ) located along the floor of the Atlantic Ocean , and part of the longest mountain range in the world . In the North Atlantic, the ridge separates the North American from the Eurasian plate and the African plate , north and south of the Azores triple junction . In the South Atlantic, it separates the African and South American plates. The ridge extends from

120-502: Is notorious for winter storms and mammoth rogue waves , which can range up to 30 metres (100 ft) high and can sink even large ships. Over the past few hundred years it has been believed that around 150 ships have sunk around Agulhas. These conditions are caused by a number of factors. The naturally strong winds of the Roaring Forties , which blow from west to east, and the cold Antarctic Circumpolar Current flowing in

144-538: Is sometimes regarded as one of the great capes . It was most commonly known in English as Cape L'Agulhas until the 20th century. The town of L'Agulhas is near the cape. Cape Agulhas is located in the Overberg region, 170 kilometres (105 mi) southeast of Cape Town . The cape was named by Portuguese navigators , who called it Cabo das Agulhas — Portuguese for "Cape of Needles"—after noticing that around

168-632: Is the geographic southern tip of Africa and the beginning of the traditional dividing line between the Atlantic and Indian oceans according to the International Hydrographic Organization . It is approximately half a degree of latitude , or 55 kilometres (34 mi), farther south than the Cape of Good Hope . Historically, the cape has been known to sailors as a major hazard on the traditional clipper route . It

192-677: The Agulhas Bank off the coast are quite shallow and are renowned as one of the best fishing grounds in South Africa. The rocks that form Cape Agulhas belong to the Table Mountain Group, often loosely termed the Table Mountain sandstone. They are closely linked to the geological formations that are exposed in the spectacular cliffs of Table Mountain, Cape Point and the Cape of Good Hope . Cape Agulhas has

216-680: The Mississippi River , Amazon River and Niger River ). The Fundy Basin on the Atlantic coast of North America between New Brunswick and Nova Scotia in Canada is evidence of the ancestral Mid-Atlantic Ridge. Cape Agulhas Cape Agulhas ( / ə ˈ ɡ ʊ l j ə s / ; Portuguese : Cabo das Agulhas [ˈkaβu ðɐz ɐˈɣuʎɐʃ] , "Cape of Needles") is a rocky headland in Western Cape , South Africa . It

240-643: The Tjörnes fracture zone connects Iceland to the Kolbeinsey Ridge . The ridge sits atop a geologic feature known as the Mid-Atlantic Rise , which is a progressive bulge that runs the length of the Atlantic Ocean, with the ridge resting on the highest point of this linear bulge. This bulge is thought to be caused by upward convective forces in the asthenosphere pushing the oceanic crust and lithosphere . This divergent boundary first formed in

264-520: The Triassic period, when a series of three-armed grabens coalesced on the supercontinent Pangaea to form the ridge. Usually, only two arms of any given three-armed graben become part of a divergent plate boundary. The failed arms are called aulacogens , and the aulacogens of the Mid-Atlantic Ridge eventually became many of the large river valleys seen along the Americas and Africa (including

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288-457: The epicenter of many earthquakes . Ewing, Heezen and Tharp discovered that the ridge is part of a 40,000-km (25,000 mile) long essentially continuous system of mid-ocean ridges on the floors of all the Earth's oceans. The discovery of this worldwide ridge system led to the theory of seafloor spreading and general acceptance of Alfred Wegener 's theory of continental drift and expansion in

312-549: The opening of the North Atlantic . As the plates began to diverge from each other, piles of lava rose to the surface, creating the ridges present on the landscape currently. The plateau is an example of ridge - hotspot interaction. The plateau resides above a hot spot on an active rift zone of the Mid-Atlantic Ridge from which extensive tholeiitic plateau basalts and a number of large rhyolitic domes have been extruded. Today, there are two main parts of

336-513: The Icelandic Plateau consists of three layers, closely mimicking the structure of oceanic crust but with one key difference, the second layer of the oceanic crust does not contain piles of lava flow like the Icelandic Plateau does. The first layer is composed of mainly sedimentary rock, the second layer is piles of lava flows, and the third layer is a thick layer of gabbro . The Icelandic Plateau began forming approximately 56 Ma, due to

360-494: The Mid-Atlantic Ridge, from north to south, with their respective highest peaks and location, are: Northern Hemisphere (North Atlantic Ridge) : Southern Hemisphere (South Atlantic Ridge) : The submarine section of the Mid-Atlantic Ridge close to southwest Iceland is known as the Reykjanes Ridge . The Mid-Atlantic Ridge runs through Iceland where the ridge is also known as the Neovolcanic Zone . In northern Iceland

384-539: The South Atlantic Ocean and take enormous amounts of heat and salt into the neighbouring ocean. This mechanism constitutes one of the key elements in the global conveyor belt circulation of heat and salt. Cape Agulhas has a gradually curving coastline with rocky and sand beaches. A survey marker and a new marker depicting the African continent are located at the most Southern tip of Africa. The waters of

408-420: The cape, after which it falls steeply away to the abyssal plain . These hazards have combined to make the cape notorious among sailors. The coast here is littered with wrecks: Arniston (1815), Geortyrder (1849), Elise (1879), Cooranga (1964), Gwendola (1968), Federal Lakes (1975), and Gouritz (1981), but these are just a few of the vessels lost in the proximity of the "Cape of Needles". Owing to

432-612: The future location for a transatlantic telegraph cable . The existence of such a ridge was confirmed by sonar in 1925 and was found to extend around Cape Agulhas into the Indian Ocean by the German Meteor expedition . In the 1950s, mapping of the Earth's ocean floors by Marie Tharp , Bruce Heezen , Maurice Ewing , and others revealed that the Mid-Atlantic Ridge had a strange bathymetry of valleys and ridges, with its central valley being seismologically active and

456-441: The island, one which is slanted towards the sea floor, and another at a level surface. 68°45′0.3″N 12°22′45.1″W  /  68.750083°N 12.379194°W  / 68.750083; -12.379194 This Iceland location article is a stub . You can help Misplaced Pages by expanding it . This oceanography article is a stub . You can help Misplaced Pages by expanding it . Reykjanes Ridge The Mid-Atlantic Ridge

480-471: The modified form of plate tectonics . The ridge is central to the breakup of the hypothetical supercontinent of Pangaea that began some 180 million years ago. The Mid-Atlantic Ridge includes a deep rift valley that runs along the axis of the ridge for nearly its entire length. This rift marks the actual boundary between adjacent tectonic plates, where magma from the mantle reaches the seafloor, erupting as lava and producing new crustal material for

504-462: The northern Atlantic Ocean was first inferred by Matthew Fontaine Maury in 1853, based on soundings by the USS Dolphin . The existence of the ridge and its extension into the South Atlantic was confirmed during the expedition of HMS Challenger in 1872. A team of scientists on board, led by Charles Wyville Thomson , discovered a large rise in the middle of the Atlantic while investigating

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528-764: The plates. Near the equator , the Mid-Atlantic Ridge is divided into the North Atlantic Ridge and the South Atlantic Ridge by the Romanche Trench , a narrow submarine trench with a maximum depth of 7,758 m (25,453 ft), one of the deepest locations of the Atlantic Ocean. This trench, however, is not regarded as the boundary between the North and South American plates, nor the Eurasian and African plates. The islands on or near

552-500: The same direction, come up against the warmer Agulhas Current in the region of the cape. These conflicting currents of water of different densities, and the west winds blowing against the Agulhas Current, can create extremely hazardous wave conditions; these are further exacerbated by the shallow waters of the Agulhas Bank , a broad, shallow part of the continental shelf which juts 250 kilometres (155 mi) south from

576-699: The year 1500 the direction of magnetic north (and therefore the compass needle) coincided with true north in the region. The cape is within the Cape Agulhas Local Municipality in the Overberg District of the Western Cape province of South Africa. South of Cape Agulhas the warm Agulhas Current that flows south along the east coast of Africa retroflects back into the Indian Ocean. While retroflecting, it pinches off large ocean eddies (Agulhas rings) that drift into

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