Which Land Feature Supports the Theory of Continental Drift

Movement of Earth’s continents relative to each other

This commodity is well-nigh the development of the continental migrate hypothesis before 1958. For the gimmicky theory, see Plate tectonics.

Continental drift
is the hypothesis that the Earth’due south continents have moved over geologic time relative to each other, thus appearing to take “drifted” across the ocean bed.^[1]
The idea of continental drift has been subsumed into the scientific discipline of plate tectonics, which studies the motility of the continents as they ride on plates of the Earth’s lithosphere.^[2]

The speculation that continents might accept ‘drifted’ was first put forwards by Abraham Ortelius in 1596. A pioneer of the mod view of mobilism was the Austrian geologist Otto Ampferer.^[3]
[4]
The concept was independently and more fully adult by Alfred Wegener in 1912, but the hypothesis was rejected by many for lack of any motive machinery. The English geologist Arthur Holmes afterwards proposed drapery convection for that machinery.

History

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Early on history

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Abraham Ortelius (Ortelius 1596),^[v]
Theodor Christoph Lilienthal (1756),^[6]
Alexander von Humboldt (1801 and 1845),^[6]
Antonio Snider-Pellegrini (Snider-Pellegrini 1858), and others had noted earlier that the shapes of continents on reverse sides of the Atlantic Ocean (about notably, Africa and South America) seem to fit together.^[seven]
W. J. Kious described Ortelius’ thoughts in this way:^[viii]

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 globe and considers carefully the coasts of the three [continents].”

In 1889, Alfred Russel Wallace remarked, “Information technology was formerly a very general conventionalities, even amongst geologists, that the cracking features of the earth’s surface, no less than the smaller ones, were bailiwick to continual mutations, and that during the course of known geological time the continents and great oceans had, again and again, inverse places with each other.”^[ix]
He quotes Charles Lyell as saying, “Continents, therefore, although permanent for whole geological epochs, shift their positions entirely in the form of ages.”^[ten]
and claims that the showtime to throw uncertainty on this was James Dwight Dana in 1849.

In his
Manual of Geology
(1863), Dana wrote, “The continents and oceans had their general outline or form divers in earliest fourth dimension. This has been proved with regard to N America from the position and distribution of the first beds of the Lower Silurian, – those of the Potsdam epoch. The facts signal that the continent of North America had its surface near tide-level, office above and office below information technology (p.196); and this will probably exist proved to be the condition in Primordial time of the other continents also. And, if the outlines of the continents were marked out, it follows that the outlines of the oceans were no less so”.^[12]
Dana was enormously influential in America—his
Manual of Mineralogy
is still in print in revised class—and the theory became known every bit the
Permanence theory.^[13]

This appeared to be confirmed by the exploration of the deep body of water beds conducted by the
Challenger
expedition, 1872–1876, which showed that contrary to expectation, land debris brought downwardly by rivers to the sea is deposited comparatively close to the shore on what is now known every bit the continental shelf. This suggested that the oceans were a permanent characteristic of the Earth’s surface, rather than them having “changed places” with the continents.^[9]

Eduard Suess had proposed a supercontinent Gondwana in 1885^[14]
and the Tethys Bounding main in 1893,^[xv]
bold a state-bridge between the present continents submerged in the course of a geosyncline, and John Perry had written an 1895 paper proposing that the earth’s interior was fluid, and disagreeing with Lord Kelvin on the historic period of the earth.^[16]

Wegener and his predecessors

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Apart from the earlier speculations mentioned above, the thought that the American continents had one time formed a single landmass with Eurasia and Africa was postulated by several scientists before Alfred Wegener’s 1912 paper.^[17]
Although Wegener’s theory was formed independently and was more consummate than those of his predecessors, Wegener later credited a number of past authors with similar ideas:^[18]
[19]
Franklin Coxworthy (betwixt 1848 and 1890),^[20]
Roberto Mantovani (between 1889 and 1909), William Henry Pickering (1907)^[21]
and Frank Bursley Taylor (1908).^[22]

The similarity of southern continent geological formations had led Roberto Mantovani to conjecture in 1889 and 1909 that all the continents had in one case been joined into a supercontinent; Wegener noted the similarity of Mantovani’s and his own maps of the former positions of the southern continents. In Mantovani’s conjecture, this continent bankrupt due to volcanic activity caused by thermal expansion, and the new continents drifted away from each other because of farther expansion of the rip-zones, where the oceans now prevarication. This led Mantovani to suggest a now-discredited Expanding Globe theory.^{[23]
[24]
[25]}

Continental drift without expansion was proposed past Frank Bursley Taylor,^[26]
who suggested in 1908 (published in 1910) that the continents were moved into their nowadays positions by a process of “continental creep”,^[27]
[28]
later proposing a mechanism of increased tidal forces during the Cretaceous dragging the crust towards the equator. He was the first to realize that 1 of the effects of continental motion would be the germination of mountains, attributing the formation of the Himalayas to the collision betwixt the Indian subcontinent with Asia.^[29]
Wegener said that of all those theories, Taylor’southward had the near similarities to his own. For a fourth dimension in the mid-20th century, the theory of continental drift was referred to every bit the “Taylor-Wegener hypothesis”.^{[26]
[29]
[30]
[31]}

Alfred Wegener first presented his hypothesis to the German language Geological Society on 6 Jan 1912.^[17]
His hypothesis was that the continents had once formed a unmarried landmass, called Pangaea, before breaking apart and globe-trotting to their nowadays locations.^[32]

Wegener was the outset to use the phrase “continental drift” (1912, 1915)^[17]
[18]
(in German “die Verschiebung der Kontinente” – translated into English in 1922) and formally publish the hypothesis that the continents had somehow “drifted” apart. Although he presented much evidence for continental drift, he was unable to provide a convincing explanation for the physical processes which might have acquired this drift. He suggested that the continents had been pulled apart by the centrifugal pseudoforce (Polflucht) of the Earth’s rotation or past a small component of astronomical precession, merely calculations showed that the force was not sufficient.^[33]
The Polflucht hypothesis was besides studied past Paul Sophus Epstein in 1920 and constitute to be implausible.

Rejection of Wegener’s theory, 1910s–1950s

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Although now accepted, the theory of continental migrate was rejected for many years, with evidence in its favor considered insufficient. One trouble was that a plausible driving strength was missing.^[1]
A second problem was that Wegener’s guess of the speed of continental motion, 250 cm/year, was implausibly loftier.^[34]
(The currently accepted charge per unit for the separation of the Americas from Europe and Africa is nearly 2.5 cm/yr).^[35]
Furthermore, Wegener was treated less seriously considering he was not a geologist. Even today, the details of the forces propelling the plates are poorly understood.^[1]

The English geologist Arthur Holmes championed the theory of continental drift at a time when it was deeply unfashionable. He proposed in 1931 that the Earth’s pall contained convection cells which dissipated estrus produced by radioactivity and moved the crust at the surface.^[36]
His
Principles of Concrete Geology, ending with a chapter on continental drift, was published in 1944.^[37]

Geological maps of the time showed huge land bridges spanning the Atlantic and Indian oceans to account for the similarities of fauna and flora and the divisions of the Asian continent in the Permian period, only failing to account for glaciation in India, Commonwealth of australia and South Africa.^[38]

The fixists

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Hans Stille and Leopold Kober opposed the idea of continental drift and worked on a “fixist”^[39]
geosyncline model with Earth contraction playing a key role in the formation of orogens.^[40]
[41]
Other geologists who opposed continental drift were Bailey Willis, Charles Schuchert, Rollin Chamberlin, Walther Bucher and Walther Penck.^[42]
[43]
In 1939 an international geological conference was held in Frankfurt.^[44]
This briefing came to be dominated by the fixists, especially as those geologists specializing in tectonics were all fixists except Willem van der Gracht.^[44]
Criticism of continental migrate and mobilism was abundant at the conference not merely from tectonicists just also from sedimentological (Nölke), paleontological (Nölke), mechanical (Lehmann) and oceanographic (Troll, Wüst) perspectives.^[44]
[45]
Hans Cloos, the organizer of the briefing, was likewise a fixist^[44]
who together with Troll held the view that excepting the Pacific Sea continents were not radically unlike from oceans in their behaviour.^[45]
The mobilist theory of Émile Argand for the Alpine orogeny was criticized by Kurt Leuchs.^[44]
The few drifters and mobilists at the conference appealed to biogeography (Kirsch, Wittmann), paleoclimatology (Wegener, K), paleontology (Gerth) and geodetic measurements (Wegener, K).^[46]
F. Bernauer correctly equated Reykjanes in south-west Iceland with the Mid-Atlantic Ridge, arguing with this that the floor of the Atlantic Ocean was undergoing extension simply like Reykjanes. Bernauer thought this extension had drifted the continents but 100–200 km apart, the estimate width of the volcanic zone in Iceland.^[47]

David Attenborough, who attended university in the second one-half of the 1940s, recounted an incident illustrating its lack of acceptance then: “I once asked one of my lecturers why he was not talking to the states about continental drift and I was told, sneeringly, that if I could prove there was a force that could movement continents, and so he might recollect about information technology. The idea was moonshine, I was informed.”^[48]

As belatedly as 1953—just five years before Carey^[49]
introduced the theory of plate tectonics—the theory of continental migrate was rejected by the physicist Scheidegger on the following grounds.^[50]

• First, it had been shown that floating masses on a rotating geoid would collect at the equator, and stay there. This would explain one, simply but i, mountain building episode between any pair of continents; it failed to account for earlier orogenic episodes.
• Second, masses floating freely in a fluid substratum, like icebergs in the ocean, should be in isostatic equilibrium (in which the forces of gravity and buoyancy are in residuum). But gravitational measurements showed that many areas are not in isostatic equilibrium.
• Tertiary, at that place was the problem of why some parts of the Earth’south surface (chaff) should have solidified while other parts were even so fluid. Various attempts to explicate this foundered on other difficulties.

Road to acceptance

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From the 1930s to the tardily 1950s, works by Vening-Meinesz, Holmes, Umbgrove, and numerous others outlined concepts that were shut or nearly identical to modernistic plate tectonics theory. In item, the English geologist Arthur Holmes proposed in 1920 that plate junctions might lie below the sea, and in 1928 that convection currents within the drapery might be the driving strength.^[51]
Holmes’ views were peculiarly influential: in his bestselling textbook,
Principles of Concrete Geology,
he included a affiliate on continental drift, proposing that Earth’s mantle contained convection cells which dissipated radioactive heat and moved the crust at the surface.^[52]
[53]
Holmes’ proposal resolved the stage disequilibrium objection (the underlying fluid was kept from solidifying by radioactive heating from the core). Withal, scientific communication in the ‘thirty and ’40s was inhibited by Earth War 2, and the theory however required piece of work to avoid foundering on the orogeny and isostasy objections. Worse, the most viable forms of the theory predicted the existence of convection cell boundaries reaching deep into the globe, that had yet to be observed.^{[
citation needed
]}

In 1947, a team of scientists led by Maurice Ewing confirmed the being of a rising in the primal Atlantic Sea, and found that the floor of the seabed below the sediments was chemically and physically different from continental crust.^[54]
[55]
Equally oceanographers continued to bathymeter the body of water basins, a system of mid-oceanic ridges was detected.  An important conclusion was that along this system, new ocean floor was being created, which led to the concept of the “Great Global Rift”.^[56]

Meanwhile, scientists began recognizing odd magnetic variations across the ocean flooring using devices developed during Earth State of war II to discover submarines.^[57]
Over the next decade, it became increasingly articulate that the magnetization patterns were not anomalies, as had been originally supposed. In a series of papers in 1959–1963, Heezen, Dietz, Hess, Mason, Vine, Matthews, and Morley collectively realized that the magnetization of the ocean floor formed all-encompassing, zebra-like patterns: one stripe would exhibit normal polarity and the adjoining stripes reversed polarity.^{[58]
[59]
[lx]}
The all-time explanation was the “conveyor belt” or Vine–Matthews–Morley hypothesis.  New magma from deep inside the Globe rises easily through these weak zones and eventually erupts along the crest of the ridges to create new oceanic crust.  The new crust is magnetized by the globe’due south magnetic field, which undergoes occasional reversals.  Formation of new crust then displaces the magnetized chaff apart, akin to a conveyor belt – hence the name.^[61]

Without workable alternatives to explain the stripes, geophysicists were forced to conclude that Holmes had been right: ocean rifts were sites of perpetual orogeny at the boundaries of convection cells.^[62]
[63]
By 1967, barely two decades later discovery of the mid-oceanic rifts, and a decade after discovery of the striping, plate tectonics had become axiomatic to modern geophysics.

In addition, Marie Tharp, in collaboration with Bruce Heezen, who initially ridiculed Tharp’due south observations that her maps confirmed continental drift theory, provided essential corroboration, using her skills in cartography and seismographic information, to confirm the theory.^{[64]
[65]
[66]
[67]
[68]}

Modernistic evidence

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Geophysicist Jack Oliver is credited with providing seismologic show supporting plate tectonics which encompassed and superseded continental migrate with the article “Seismology and the New Global Tectonics”, published in 1968, using information collected from seismologic stations, including those he fix in the South Pacific.^[69]
[70]
The modernistic theory of plate tectonics, refining Wegener, explains that there are two kinds of crust of dissimilar composition: continental chaff and oceanic crust, both floating to a higher place a much deeper “plastic” mantle. Continental crust is inherently lighter. Oceanic chaff is created at spreading centers, and this, along with subduction, drives the system of plates in a cluttered manner, resulting in continuous orogeny and areas of isostatic imbalance.

Evidence for the motility of continents on tectonic plates is at present extensive. Like plant and animal fossils are plant effectually the shores of dissimilar continents, suggesting that they were in one case joined. The fossils of
Mesosaurus, a freshwater reptile rather like a pocket-sized crocodile, found both in Brazil and Due south Africa, are one example; another is the discovery of fossils of the state reptile
Lystrosaurus
in rocks of the same age at locations in Africa, Republic of india, and Antarctica.^[71]
There is also living prove, with the aforementioned animals existence found on 2 continents. Some earthworm families (such as Ocnerodrilidae, Acanthodrilidae, Octochaetidae) are found in South America and Africa.

The complementary organization of the facing sides of South America and Africa is obvious just a temporary coincidence. In millions of years, slab pull, ridge-push, and other forces of tectonophysics will further divide and rotate those two continents. Information technology was that temporary characteristic that inspired Wegener to report what he defined equally continental migrate although he did not alive to see his hypothesis more often than not accepted.

The widespread distribution of Permo-Carboniferous glacial sediments in South America, Africa, Republic of madagascar, Arabia, Bharat, Antarctica and Australia was 1 of the major pieces of show for the theory of continental drift. The continuity of glaciers, inferred from oriented glacial striations and deposits called tillites, suggested the being of the supercontinent of Gondwana, which became a cardinal element of the concept of continental drift. Striations indicated glacial catamenia abroad from the equator and toward the poles, based on continents’ current positions and orientations, and supported the thought that the southern continents had previously been in dramatically different locations that were face-to-face with one another.^[18]

Come across besides

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• Geological history of Earth – The sequence of major geological events in World’s past
• State of israel C. White

References

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Sources

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• Frankel, Henry R. (2012).
  The Continental Drift Controversy. Vol. I:
  Wegener and the Early Contend. Cambridge.
  
• Le Thou, Homer Eugene (1988),
  
  Globe-trotting Continents and Shifting Theories
  , Cambridge Academy, ISBN978-0-521-31105-2
  
  
• Oreskes, Naomi (1999),
  The Rejection of Continental Drift, Oxford Academy Press, ISBN978-0-19-511732-five
  
  
  (lead: 0-xix-511733-6)
• Oreskes, Naomi (2002), “Continental Migrate”
  (PDF), in Munn, Ted; MacCracken, Michael C.; Perry, John S. (eds.),
  Encyclopedia of Global Environmental Alter, vol. 1, Chichester, West Sussex: John Wiley & Sons, pp. 321–325, ISBN978-0-471-97796-four, OCLC 633880622, archived from the original
  (PDF)
  on 4 February 2012
  
• Ortelius, Abraham (1596) [1570],
  Thesaurus Geographicus
  (in Latin) (3 ed.), Antwerp: Plantin, OCLC 214324616
  
  (First edition published 1570, 1587 edition online)
• Şengör, Celâl (1982). “Classical theories of orogenesis”. In Miyashiro, Akiho; Aki, Keiiti; Şengör, Celâl (eds.).
  Orogeny. John Wiley & Sons. ISBN978-0-471-103769.
  
• Snider-Pellegrini, Antonio (1858),
  La Création et ses mystères dévoilés, Paris: Frank and Dentu
  .

External links

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• Benjamin Franklin (1782) and Ralph Waldo Emerson (1834) noted Continental Migrate
• A brief introduction to Plate Tectonics, based on the work of Alfred Wegener
• Animation of continental migrate for last one billion years
• Maps of continental drift, from the Precambrian to the future