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Encyclopedia > Continental drift
Plates in the crust of the earth, according to the plate tectonics theory
Plates in the crust of the earth, according to the plate tectonics theory

Continental drift refers to the movement of the Earth's continents relative to each other. The hypothesis that continents 'drift' was first put forward by Abraham Ortelius in 1596 and was fully developed by Alfred Wegener in 1912. However, only with the development of the theory of plate tectonics in the 1960s a sufficient geological explanation of the cause of their movement could be found. (This article gives an overview about the development of the continental drift hypothesis before 1950. For the contemporary theory, see the article plate tectonics.) Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... The tectonic plates of the world were mapped in the second half of the 20th century. ... This article is about Earth as a planet. ... Dymaxion map by Buckminster Fuller shows land mass with minimal distortion as only one continuous continent A continent (Latin continere, to hold together) is a large continuous mass of land on the planet Earth. ... Abraham Ortelius. ... Alfred Wegener, around 1925 Alfred Lothar Wegener (Berlin, November 1, 1880 – Greenland, November 2 or 3, 1930) was a German interdisciplinary scientist and meteorologist, who became famous for his theory of continental drift (Kontinentalverschiebung or die Verschiebung der Kontinente in his words). ... The tectonic plates of the world were mapped in the second half of the 20th century. ... This article includes a list of works cited but its sources remain unclear because it lacks in-text citations. ... The tectonic plates of the world were mapped in the second half of the 20th century. ...

Contents

History

Early history

Antonio Snider-Pellegrini's Illustration of the closed and opened atlantic ocean (1858).
Antonio Snider-Pellegrini's Illustration of the closed and opened atlantic ocean (1858).

Abraham Ortelius (1596), Francis Bacon (1620), Benjamin Franklin, Antonio Snider-Pellegrini (1858), and others had noted earlier that the shapes of continents on either side of the Atlantic Ocean (most notably, Africa and South America) seem to fit together. W. J. Kious described Ortelius' thoughts in this way:[1] Abraham Ortelius. ... For other persons named Francis Bacon, see Francis Bacon (disambiguation). ... Benjamin Franklin (January 17 [O.S. January 6] 1706 – April 17, 1790) was one of the most well known Founding Fathers of the United States. ... Wikipedia does not have an article with this exact name. ... Animated, colour-coded map showing the various continents. ...

Abraham Ortelius in his work Thesaurus Geographicus ... suggested that the Americas were "torn away from Europe and Africa ... by earthquakes and floods" and went on to say: "The vestiges of the rupture reveal themselves, if someone brings forward a map of the world and considers carefully the coasts of the three [continents].

Wegener and his predecessors

The hypothesis that the continents once formed a single landmass, broke up, and drifted to their present locations was fully elaborated by Alfred Wegener in 1912. [2] Wegener himself said in 1929, that he was not the first to propose such an idea. [3] [4] He mentioned the following predecessors: Franklin Coxworthy (between 1848 and 1890), [5] Roberto Mantovani (between 1889 and 1909), William Henry Pickering (1907) [6] and Frank Bursley Taylor (1908). Wegener clearly stated, that he created his theory independent of those authors. And it must be said that Wegener's theory was the most elaborated one. Alfred Wegener, around 1925 Alfred Lothar Wegener (Berlin, November 1, 1880 – Greenland, November 2 or 3, 1930) was a German interdisciplinary scientist and meteorologist, who became famous for his theory of continental drift (Kontinentalverschiebung or die Verschiebung der Kontinente in his words). ... Roberto Mantovani (* March 25, 1854 in Parma, † January 10, 1933 in Paris) was an violinist and scientist from Italy. ... William Henry Pickering (February 15, 1858 – January 17, 1938) was an American astronomer, brother of Edward Charles Pickering. ... Frank Bursley Taylor, [b. ...


For example: The similarity of southern continent geological formations had led Roberto Mantovani to conjecture in 1889 and 1909 that all the continents had once been joined into a supercontinent (now known as Pangaea). (Regarding the former positions of the southern continents, Wegener himself also noted the similarity of Mantovani's and his own maps). Through volcanic activity because of thermal expansion this continent broke, whereby the new continents were drifting away from each other because of further expansion of the rip-zones, where now the oceans lie. However, this led Mantovani to propose an expanding earth theory, which is now considered to be superseded. [7] [8] [9] Some sort of continental drift at constant earth radius was proposed by Frank Bursley Taylor, who suggested in 1908 (published in 1910) that the continents were dragged towards the equator by increased lunar gravity during the Cretaceous, thus forming the Himalaya and Alps on the southern faces. Wegener said that from all those theories, Taylor's theory (although not fully developed) had the most similarities to his own theory. [10] Roberto Mantovani (* March 25, 1854 in Parma, † January 10, 1933 in Paris) was an violinist and scientist from Italy. ... In geology, a supercontinent is a land mass comprising more than one continental core, or craton. ... For other uses, see Pangaea (disambiguation). ... This article is about volcanoes in geology. ... In physics, thermal expansion is the tendency of matter to change in volume in response to a change in temperature. ... Movements of the continents as the Earth expands. ... Frank Bursley Taylor, [b. ... // The Cretaceous Period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic Period (i. ...


Wegener was the first to use the phrase "continental drift" (1912, 1915) [2] [3] (in German "die Verschiebung der Kontinente") and formally publish the hypothesis that the continents had somehow "drifted" apart. And although he presented much evidence for continental drift, he was unable to provide a convincing explanation for the physical processes which might have caused this drift. His suggestion that the continents had been pulled apart by the centrifugal pseudoforce of the Earth's rotation was considered unrealistic by the scientific community.[11] Centrifugal force (from Latin centrum centre and fugere to flee) is a term which may refer to two different forces which are related to rotation. ...


Controversial years

Wegener's hypothesis received support through the controversial years from South African geologist Alexander Du Toit as well as from Arthur Holmes. The idea of continental drift did not become widely accepted even as theory until the late 1950s. By the 1960s, geological research conducted by Robert S. Dietz, Bruce Heezen, and Harry Hess, along with a rekindling of the theory including a mechanism by J. Tuzo Wilson led to widespread acceptance of the theory among geologists. Alexander Logie du Toit (March 14, 1878 – February 25, 1948) was a South African geologist. ... Arthur Holmes (January 14, 1890 – September 20, 1965) was a British geologist. ... The word theory has a number of distinct meanings in different fields of knowledge, depending on their methodologies and the context of discussion. ... Robert Sinclair Dietz (September 14, 1914 - May 19, 1995) was Professor of Geology at Arizona State University. ... Bruce C. Heezen (1924 - June 21, 1977) was a geologist. ... Harry Hammond Hess (1906-1969) was an American geologist. ... John Tuzo Wilson (October 24, 1908-April 15, 1993) was a Canadian geophysicist and geologist who achieved worldwide acclaim for his theory of plate tectonics, the assumption that the Earths crust is comprised of plates floating on magma. ...


Evidence

For more details on this topic, see Plate tectonics.

Note: This section contains evidence available to Wegener's contemporaries and predecessors The tectonic plates of the world were mapped in the second half of the 20th century. ...

Fossil patterns across continents.
Pangaea separation animation

The notion that continents have not always been at their present positions was suggested as early as 1596 by the Dutch map maker Abraham Ortelius in the third edition of his work Thesaurus Geographicus. Ortelius suggested that the Americas, Eurasia and Africa were once joined and have since drifted apart "by earthquakes and floods", creating the modern Atlantic Ocean. For evidence, he wrote: "The vestiges of the rupture reveal themselves, if someone brings forward a map of the world and considers carefully the coasts of the three continents." Francis Bacon commented on Ortelius' idea in 1620, as did Benjamin Franklin and Alexander von Humboldt in later centuries. Continental drift fossil evidence. ... Continental drift fossil evidence. ... Image File history File links Pangea_animation_03. ... Image File history File links Pangea_animation_03. ... Abraham Ortelius. ... For other persons named Francis Bacon, see Francis Bacon (disambiguation). ... Benjamin Franklin (January 17 [O.S. January 6] 1706 – April 17, 1790) was one of the most well known Founding Fathers of the United States. ... An 1859 portrait of Alexander von Humboldt by the artist Julius Schrader, showing Mount Chimborazo in the background. ...


Evidence for continental drift is now extensive, in the form of plant and animal fossils of the same age found around different continent shores, suggesting that these shores were once joined: the fossils of the freshwater crocodile, found in Brazil and South Africa, are one example. Another is the discovery of fossils of the aquatic reptile Lystrosaurus from rocks of the same age from locations in South America, Africa, and Antarctica. There is also living evidence — the same animals being found on two continents. An example of this is a particular earthworm found in South America and South Africa. For other uses, see Fossil (disambiguation). ... For other uses, see Crocodile (disambiguation). ... Reptilia redirects here. ... Species Lystrosaurus curvatus Lystrosaurus declivus Lystrosaurus mccaigi Lystrosaurus murrayi Lystrosaurus oviceps Lystrosaurus platyceps Distribution of Lystrosaurus (brown) in the Gondwana supercontinent. ... This article is about the geological substance. ... South America South America is a continent crossed by the equator, with most of its area in the Southern Hemisphere. ... A world map showing the continent of Africa Africa is the worlds second-largest and second most-populous continent, after Asia. ... For the LPG album, see The Earthworm (album). ...


The complementary arrangement of the facing sides of South America and Africa is obvious, but is a temporary coincidence. In millions of years, seafloor spreading, continental drift, and other forces of tectonophysics will further separate and rotate those two continents. It was this temporary feature which inspired Wegener to study what he defined as continental drift. He never lived to see his hypothesis be proven true. Tectonophysics, a branch of geophysics, is the study of rock deformation and of dynamic geophysical processes. ...


Widespread distribution of Permo-Carboniferous glacial sediments in South America, Africa, Madagascar, Arabia, India, Antarctica and Australia was one of the major pieces of evidence for the theory of continental drift. The continuity of glaciers, inferred from oriented glacial striations and deposits called tillites, suggested the existence of the supercontinent of Gondwana, which became a central element of the concept of continental drift. Striations indicated glacial flow away from the equator and toward the poles, in modern coordinates, and was a good indicator of the fact that the southern continents had previously been in dramatically different locations, as well as contiguous with each other. Permo-Carboniferous is strata deposited between the Carboniferous and Permian periods that are not differentiated because of the presence of transitional fossils, and also where no conspicuous stratigraphic break is present. ... Bodybuilding In bodybuilding, striations are the tiny grooves of muscle across major muscle groups characteristic of a well-developed body. ... Tillite is lithified till. ... For other uses of Gondwana and Gondwanaland, see Gondwana (disambiguation). ...


Debate

Before geophysical evidence started accumulating after World War II, the idea of continental drift caused sharp disagreement among geologists. Wegener had introduced his theory in 1912 at a meeting of the German Geological Association. His paper was published that year and expanded into a book in 1915. In 1921 the Berlin Geological Society held a symposium on the theory. In 1922 Wegener's book was translated into English and then it received a wider audience. In 1923 the theory was discussed at conferences by Geological Society of France, the Geological Section of the British Association for the Advancement of Science, and the Royal Geological Society. The theory was carefully but critically reviewed in the journal Nature by Philip Lake.[12] On November 15, 1926, the American Association of Petroleum Geologists (AAPG) held a symposium at which the continental drift hypothesis was vigorously debated. The resulting papers were published in 1928 under the title Theory of continental drift. Wegener himself contributed a paper to this volume.[13] ‹ The template below has been proposed for deletion. ... Combatants Allied powers: China France Great Britain Soviet Union United States and others Axis powers: Germany Italy Japan and others Commanders Chiang Kai-shek Charles de Gaulle Winston Churchill Joseph Stalin Franklin Roosevelt Adolf Hitler Benito Mussolini Hideki Tōjō Casualties Military dead: 17,000,000 Civilian dead: 33,000... The British Association or the British Association for the Advancement of Science or the BA is a learned society with the object of promoting science, directing general attention to scientific matters, and facilitating intercourse between scientific workers. ... is the 319th day of the year (320th in leap years) in the Gregorian calendar. ... Year 1926 (MCMXXVI) was a common year starting on Friday (link will display the full calendar) of the Gregorian calendar. ... The American Association of Petroleum Geologists (or AAPG) is currently the worlds largest professional geological society with over 30,000 members as of 2004. ...


One of the main problems with Wegener's theory was that he believed that the continents "plowed" through the rocks of the ocean basins. Most geologists did not believe that this could be possible. In fact, the biggest objection to Wegener was that he did not have an acceptable theory of the forces that caused the continents to drift. He also ignored counter-arguments and evidence contrary to his theory and seemed too willing to interpret ambiguous evidence as being favorable to his theory.[14] For their part, the geologists ignored Wegener's copious body of evidence, allowing their adherence to a theory to override the actual data, when the scientific method would seem to demand the reverse approach. Scientific method is a body of techniques for investigating phenomena, acquiring new knowledge, or correcting and integrating previous knowledge. ...


Plate tectonics, a modern update of the old ideas of Wegener about "plowing" continents, accommodates continental motion through the mechanism of seafloor spreading. New rock is created by volcanism at mid-ocean ridges and returned to the Earth's mantle at ocean trenches. Remarkably, in the 1928 AAPG volume, G. A. F. Molengraaf of the Delft Institute (now University) of Technology proposed a recognizable form of seafloor spreading in order to account for the opening of the Atlantic Ocean as well as the East Africa Rift. Arthur Holmes (an early supporter of Wegener) suggested that the movement of continents was the result of convection currents driven by the heat of the interior of the Earth, rather than the continents floating on the mantle. In the words of Carl Sagan,[15] it is more like the continents are being carried on a conveyor belt than floating or drifting. The ideas of Molengraaf and of Holmes led to the theory of plate tectonics, which replaced the theory of continental drift, and became the accepted theory in the 1960s (based on data that started to accumulate in the late 1950s). The tectonic plates of the world were mapped in the second half of the 20th century. ... Age of oceanic crust. ... Founded in 1842, the Delft University of Technology, in Delft, the Netherlands, is one of the oldest, largest, and most comprehensive technical universities in the Netherlands, with over 13,000 students and 2,100 scientists (including 200 professors). ... Northern section of the Great Rift Valley. ... Insert non-formatted text here Carl Edward Sagan (November 9, 1934 – December 20, 1996) was an American astronomer and astrobiologist and a highly successful popularizer of astronomy, astrophysics, and other natural sciences. ...


However, acceptance was gradual. Nowadays it is universally supported; but even in 1977 a textbook could write the relatively weak: "a poll of geologists now would probably show a substantial majority who favor the idea of drift" and devote a section to a serious consideration of the objections to the theory.[16]


Notes and references

  1. ^ Kious, W.J.; Tilling, R.I. [February 1996]. "Historical perspective", This Dynamic Earth: the Story of Plate Tectonics, Online edition, U.S. Geological Survey. ISBN 0160482208. Retrieved on 2008-01-29. 
  2. ^ a b Wegener, A. (1912), "Die Entstehung der Kontinente", Peterm. Mitt.: 185—195, 253—256, 305—309
  3. ^ a b Wegener, A. (1929/1966), The Origin of Continents and Oceans, Courier Dover Publications, ISBN 0486617084
  4. ^ Wegener, A. (1929), Die Entstehung der Kontinente und Ozeane, 4. Auflage, Braunschweig: Friedrich Vieweg & Sohn Akt. Ges.
  5. ^ Coxworthy, F. (1848/1924), Electrical Condition or How and Where our Earth was created, London: W. J. S. Phillips
  6. ^ Pickering, W.H (1907), "The Place of Origin of the Moon - The Volcani Problems", Popular Astronomy: 274-287
  7. ^ Mantovani, R. (1889), "Les fractures de l’écorce terrestre et la théorie de Laplace", Bull. Soc. Sc. et Arts Réunion: 41-53
  8. ^ Mantovani, R. (1909), "L’Antarctide", Je m’instruis. La science pour tous 38: 595-597
  9. ^ Scalera, G. (2003), "Roberto Mantovani an Italian defender of the continental drift and planetary expansion", in Scalera, G. and Jacob, K.-H., Why expanding Earth? – A book in honour of O.C. Hilgenberg, Rome: Istituto Nazionale di Geofisica e Vulcanologia, pp. 71-74
  10. ^ Taylor, F.B. (1910), "Bearing of the tertiary mountain belt on the origin of the earth's plan", GSA Bulletin 21 (2): 179-226
  11. ^ Plate Tectonics: The Rocky History of an Idea
  12. ^ P. Lake, 'Wegener's Hypothesis of Continental Drift', Nature CXI, 1923a, pp. 226-228
  13. ^ Friedlander, Michael W. (1995) At the Fringes of Science, pages 21-27, Westview, ISBN 0-8133-2200-6, 1998 edition with new epilog: ISBN 0-8133-9060-5
  14. ^ William F. Williams, editor (2000) Encyclopedia of Pseudoscience: From Alien Abductions to Zone Therapy Facts on File p. 59 ISBN 0-8160-3351-X
  15. ^ Sagan, Carl. (1997) The Demon-Haunted World, Science As a Candle in the Dark, Ballantine Books, ISBN 0-345-40946-9. 1996 hardback edition: Random House, ISBN 0-394-53512-X pp. 302-03
  16. ^ Davis, Richard A. (1977) Principles of Oceanography, 2nd edition, Addison-Wesley, ISBN 0-201-01464-5
  • Le Grand, H. E. (1988). Drifting Continents and Shifting Theories. Cambridge University. ISBN 0-521-31105-5. 

2008 (MMVIII) is the current year, a leap year that started on Tuesday of the Anno Domini (or common era), in accordance to the Gregorian calendar. ... is the 29th day of the year in the Gregorian calendar. ... Encyclopedia of Pseudoscience book cover The Encyclopedia of Pseudoscience (2000), edited by Dr William F. Williams, identifies, defines and explains all the terms and concepts related to the murky world of almost science.[1] It includes over 2000 entries, covering phenomena, people, events, topics places and associations. ... The Demon-Haunted World: Science as a Candle in the Dark is a 1997 book by Carl Sagan. ... Pearson can mean Pearson PLC the media conglomerate. ...

External links


  Results from FactBites:
 
Continental drift - Wikipedia, the free encyclopedia (1494 words)
Continental drift, first proposed as a theory by Alfred Wegener in 1912, is the movement of the Earth's continents relative to each other.
The hypothesis of continental drift became part of the larger theory of plate tectonics.
Evidence for continental drift is now extensive, in the form of plant and animal fossils of the same age found around different continent shores, suggesting that these shores were once joined: the fossils of the freshwater crocodile, found in Brazil and South Africa, are one example.
  More results at FactBites »

 
 

COMMENTARY     

Richard Welch
28th June 2010
The lack of a convincing mechanism to account for continental drift has bedeviled the theory since its inception. Even the convection cell-conveyor belt theory has serious problems. However, the concept of geopulsation resolves the issue, easily providing the required lateral stresses(See Roots of Cataclysm, Algora Publ. NY 2009).

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