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The Location of the Mid Atlantic Ridge
The Location of the Mid Atlantic Ridge
The ridge was central in the breakup of Pangaea that began some 180 million years ago.
The ridge was central in the breakup of Pangaea that began some 180 million years ago. Pangaea, Pangæa or Pangea (pænˈdʒiːə from παν pan, meaning entire, and Γαῖα Gaea, meaning Earth in
A fissure running along the Mid Atlantic Ridge in Iceland
A fissure running along the Mid Atlantic Ridge in Iceland

The Mid-Atlantic Ridge (MAR) is a mid-ocean ridge, a divergent tectonic plate boundary located along the floor of the Atlantic Ocean. In Anatomy, fissure ( Latin fissura, Plural fissurae) is a groove natural division deep furrow cleft or tear in various parts of Iceland, officially the Republic of Iceland ( ( Ísland or Lýðveldið Ísland ( A mid-ocean ridge or mid-oceanic ridge is an underwater Mountain range typically having a valley known as a Rift running along its axis formed by This article discusses the geologic usage for the philosophical or architectural usage see Architectonics ' Or see Plate tectonics. It separates the Eurasian Plate and North American Plate in the North Atlantic, and the African Plate from the South American Plate in the South Atlantic. The Eurasian Plate is a Tectonic plate which includes most of the continent of Eurasia (a landmass consisting of the traditional Continents of Europe The North American Plate is a Tectonic plate covering most of North America, Greenland and part of Siberia. The African Plate is a Tectonic plate which includes the Continent of Africa, as well as oceanic crust which lies between the continent and various surrounding The South American Plate is a Tectonic plate covering the Continent of South America and extending eastward to the Mid-Atlantic Ridge. The MAR extends from a junction with the Gakkel Ridge (Mid-Arctic Ridge) northeast of Greenland southward to the Bouvet Triple Junction in the South Atlantic. The Gakkel Ridge (formerly known as the Nansen Cordillera and Arctic Mid-Ocean Ridge) is a Mid-oceanic ridge, a divergent tectonic plate boundary Greenland (Kalaallit Nunaat meaning "Land of the Greenlanders" Grønland is a self-governing Danish Province located between the The Bouvet Triple Junction is a geologic Triple junction of three Tectonic plates located on the seafloor of the South Atlantic Ocean. Although the Mid-Atlantic Ridge is mostly an underwater feature, portions of it have enough elevation to extend above sea level. The section of the ridge which includes the island of Iceland is also known as the Reykjanes Ridge.

Contents

Discovery

A ridge under the Atlantic Ocean was first inferred by Matthew Fontaine Maury in 1850. Matthew Fontaine Maury ( January 14, 1806 &ndash February 1, 1873) USN was an American Astronomer, The ridge was discovered during the expedition of the HMS Challenger in 1872. The Challenger Expedition was a scientific expedition that made many discoveries to lay the foundation of Oceanography. A team of scientists on board, led by Charles Wyville Thomson, discovered a large rise in the middle of the Atlantic while investigating the future location for a transatlantic telegraph cable. Professor Sir Charles Wyville Thomson ( March 5, 1830 &ndash March 10, 1882) was Professor of Zoology The first transatlantic Telegraph Cable crossed the Atlantic Ocean from Foilhommerum Valentia Island, in western Ireland to [1] The existence of such a ridge was confirmed by sonar in 1925. [2] In the 1950s, mapping of the Earth’s ocean floors by Bruce Heezen, Maurice Ewing, Marie Tharp and others, revealed the Mid-Atlantic Ridge to have a strange bathymetry of valleys and ridges,[3] with its central valley being seismologically active and the epicentre of many earthquakes. Bruce Charles Heezen ( April 11, 1924 – June 21, 1977) was an American geologist William Maurice "Doc" Ewing ( May 12 1906 &ndash May 4 1974) was an American geophysicist and oceanographer Marie Tharp ( July 30, 1920 - August 23, 2006) was a Geologist and oceanographic cartographer who along Bathymetry is the underwater equivalent to Hypsometry. The name comes from Greek βαθυς deep, and μετρον measure. Seismology (from Greek grc σεισμός seismos, "earthquake" and grc -λογία -logia) is the scientific study of Earthquakes The epicenter or epicentre is the point on the Earth 's surface that is directly above the Hypocenter or focus the point where an Earthquake An earthquake is the result of a sudden release of energy in the Earth 's crust that creates Seismic waves Earthquakes are recorded with a Seismometer [4][5] Ewing and Heezen discovered the ridge to be part of a 40,000-km-long essentially continuous system of mid-ocean ridges on the floors of all the Earth’s oceans. [6] The discovery of this world-wide ridge system led to the theory of seafloor spreading and general acceptance of Wegener's theory of continental drift. Seafloor spreading occurs at Mid-ocean ridges where new Oceanic crust is formed through volcanic activity and then gradually moves away from the ridge Alfred Lothar Wegener ( November 1, 1880 – November 2 or 3 1930 was a German Scientist and Meteorologist. Continental drift is the movement of the Earth 's Continents relative to each other

Notable features along the ridge

The Mid-Atlantic Ridge includes a deep rift valley which runs along the axis of the ridge along 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 the plates. Magma (Plurals magmas and magmata) is molten rock that sometimes forms beneath the surface of the Earth (or any other Terrestrial planet Lava is molten rock expelled by a Volcano during an eruption When first expelled from a volcanic vent it is a Liquid at Temperatures

Near the equator, the Mid-Atlantic Ridge is dissected 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. The equator (sometimes referred to colloquially as "the Line") is the intersection of the Earth 's surface with the plane perpendicular to the The Romanche Trench, also called the Romanche Furrow or Romanche Gap, is the third deepest of the major trenches of the Atlantic Ocean, after This trench, however, is not regarded as the boundary between the North and South American Plates, nor the Eurasian and African Plates.

Islands on the Mid-Atlantic Ridge

The islands, from north to south, with their respective highest peaks and location, are:

Northern Hemisphere (North Atlantic Ridge):

  1. Jan Mayen (Beerenberg, 2277 m (at 71° 06' N, 08° 12' W), in the Arctic Ocean
  2. Iceland (Hvannadalshnúkur in the Vatnajökull, 2109. Jan Mayen Island is a 55 km (34 miles long (southwest-northeast and 373 km² (144  mi²) in area Arctic Volcanic island in the Beerenberg is the world's northernmost active Volcano located at the island Jan Mayen. The Arctic Ocean, located in the Northern Hemisphere and mostly in the Arctic north polar region is the smallest and shallowest of the world's five major Iceland, officially the Republic of Iceland ( ( Ísland or Lýðveldið Ísland ( Hvannadalshnúkur or Hvannadalshnjúkur (ˈxwanːatalsˌn̥ʲuːkʏr is a peak in the north-western rim of the Öræfajökull Volcano in Vatnajökull ( English: Glacier of Rivers (ˈvahtnaˌjœːkʏtl ̥ is the largest glacier in Iceland. 6 m (at 64° 01' N, 16° 41' W), which the ridge runs through
  3. Azores (Ponta do Pico or Pico Alto, on Pico Island, 2351 m, (at 38°28′0″N, 28°24′0″W)
  4. Bermuda (Town Hill, on Main Island, 76 m (at 32° 18′ N, 64° 47′ W) (Bermuda was formed on the ridge, but is now considerably west of it)
  5. Saint Peter and Paul Rocks (Southwest Rock, 22. The Azores ( Açores ɐˈsoɾɨʃ or) is a Portuguese Archipelago in the Atlantic Ocean, about 1500 km (950  mi) from Mount Pico ( Ponta do Pico, in Portuguese) is a Stratovolcano and the highest point on Pico Island in the Azores. Pico Island ( Portuguese: Ilha do Pico, pron 'iʎɐ du 'piku is an island of the Azores noted for its eponymous Volcano, Ponta Ba (officially The Bermuda Islands or The Somers Isles) is a British overseas territory in the North Atlantic Ocean. The Saint Peter and Saint Paul Islets, officially the Arquipélago de São Pedro e São Paulo, is an archipelago of the State of Pernambuco, in Brazilian 5 m, at 00°55′08″N, 29°20′35″W)

Southern Hemisphere (South Atlantic Ridge):

  1. Ascension Island (The Peak, Green Mountain, 859 m, at 7° 59' S, 14° 25' W)
  2. Tristan da Cunha (Queen Mary's Peak, 2062 m, at 37° 05' S, 12° 17' W)
  3. Gough Island (Edinburgh Peak, 909 m, at 40° 20' S, 10° 00' W)
  4. Bouvet Island (Olavtoppen, 780 m, at 54° 24' S, 03° 21' E)

Geology

For a general explanation of mid-oceanic ridges, see mid-oceanic ridge and seafloor spreading

The ridge actually sits atop a geologic feature known as the Mid-Atlantic Rise which is a progressive bulge that also runs the length of the Atlantic Ocean with the ridge resting on the highest point of this linear bulge. Ascension Island is an island in the South Atlantic Ocean, around from the coast of Africa Tristan da Cunha (ˈtrɪstən də ˈkuːnə is a group of remote volcanic Islands in the south Atlantic Ocean, 2816 km (1750 miles from South Queen Mary's Peak is the highest mountain in the South Atlantic Ocean, situated on the Island of Tristan da Cunha, an overseas territory of the Gough Island (rhymes with cough; also known historically as Diego Alvarez) is a Volcanic island rising from the South Atlantic Ocean to Bouvet Island (Bouvetøya also historically known as Liverpool Island or Lindsay Island) is an uninhabited Sub-antarctic volcanic Island Bouvet Island (Bouvetøya also historically known as Liverpool Island or Lindsay Island) is an uninhabited Sub-antarctic volcanic Island A mid-ocean ridge or mid-oceanic ridge is an underwater Mountain range typically having a valley known as a Rift running along its axis formed by Seafloor spreading occurs at Mid-ocean ridges where new Oceanic crust is formed through volcanic activity and then gradually moves away from the ridge This bulge is thought to be caused by upward convective forces in the asthenosphere pushing the oceanic crust and lithosphere. The asthenosphere (from an invented Greek a + ' sthenos "without strength" and Greek word σφαίρα (sphera meaning globe is the Oceanic crust is the part of Earth's Lithosphere that surfaces in the Ocean basins The lithosphere (IPA, from the Greek λίθος for "rocky" + σφαίρα for "sphere" is the solid outermost shell of a rocky Planet.

This divergent boundary first formed in the Triassic period when a series of three-armed grabens coalesced on the supercontinent Pangaea to form the ridge. The Triassic is a geologic period and system that extends from about 251 to 199 Ma (million years ago A triple junction is the point where the boundaries of three Tectonic plates meet A graben is a depressed block of land bordered by parallel faults Graben is German for ditch. Pangaea, Pangæa or Pangea (pænˈdʒiːə from παν pan, meaning entire, and Γαῖα Gaea, meaning Earth in 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 the Mississippi River, Amazon River and Niger River). In Geology, an aulacogen is a failed arm of a Triple junction of a Plate tectonics rift system The Americas are the lands of the Western hemisphere or New World, consisting of the Continents of North America and South America The Mississippi River is the second longest River in the United States, with a length of from its source in Lake Itasca in Minnesota to The Amazon River (Rio Amazonas Río Amazonas of South America is the largest river in the world by volume with a total river flow greater than the next top ten largest rivers The Niger River (ˈnaɪdʒɚ NYE-jer) is the principal River of western Africa, extending about 4180 km (2600 miles

The ridge is about 2,500 meters (8,200 ft) below sea level, while its flank is about 5,000 meters deeper.

Evidence of the ancestral Mid-Atlantic Ridge can be found at the Bay of Fundy on the Atlantic coast of North America between New Brunswick and Nova Scotia in Canada. Tides Folklore in the Mi'kmaq First Nation claims that the tides in the Bay of Fundy are caused by a giant whale splashing in the water New Brunswick ( French: Nouveau-Brunswick /nuvobʁɔnzwik/ is one of Canada 's three Maritime provinces and is the only constitutionally Nova Scotia (ˌnəʊvəˈskəʊʃə ( Latin for New Scotland; Alba Nuadh Nouvelle-Écosse is a Canadian province located on Canada 's

See also

References

  1. ^ Redfern, R. ; 2001: Origins, the Evolution of Continents, Oceans and Life, University of Oklahoma Press, ISBN 1841881929, p. University of Oklahoma, abbreviated OU, is a Coeducational public Research university located in the U 26
  2. ^ Alexander Hellemans and Brian Bunch, 1989, Timeline of Science, Sidgwick and Jackson, London
  3. ^ Ewing, W.M.; Dorman, H. William Maurice "Doc" Ewing ( May 12 1906 &ndash May 4 1974) was an American geophysicist and oceanographer J. ; Ericson, J. N. & Heezen, B.C.; 1953: Exploration of the northwest Atlantic mid-ocean canyon, Bulletin of the Geological Society of America 64, p. Bruce Charles Heezen ( April 11, 1924 – June 21, 1977) was an American geologist The '''Geological Society of America''' (or GSA) is a nonprofit organization dedicated to the advancement of the Geosciences The society was founded in New York 865-868
  4. ^ Heezen, B. C. & Tharp, M.; 1954: Physiographic diagram of the western North Atlantic, Bulletin of the Geological Society of America 65, p. Marie Tharp ( July 30, 1920 - August 23, 2006) was a Geologist and oceanographic cartographer who along The '''Geological Society of America''' (or GSA) is a nonprofit organization dedicated to the advancement of the Geosciences The society was founded in New York 1261
  5. ^ Hill, M. N. & Laughton, A. S. ; 1954: Seismic Observations in the Eastern Atlantic, 1952, Proceedings of the Royal Society of London, series A, mathematical & physical sciences 222(1150), p. The Royal Society of London for the Improvement of Natural Knowledge, known simply as The Royal Society, is a Learned society for science that was founded in 1660 348-356
  6. ^ Edgar W. Spencer, 1977, Introduction to the Structure of the Earth, 2nd edition, McGraw-Hill, Tokyo
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