20150508 - continental drift

Continental drift is the movement of the Earth's continents relative to each other, thus appearing to "drift" across the ocean bed. The speculation that continents might have 'drifted' was first put forward by Abraham Ortelius in 1596. The concept was independently and more fully developed by Alfred Wegener in 1912, but his theory was rejected by some for lack of a mechanism (though this was supplied later by Holmes) and others because of prior theoretical commitments. The idea of continental drift has been subsumed by the theory of plate tectonics, which explains how the continents move.
In 1858 Antonio Snider-Pellegrini created two maps demonstrating how America and Africa continents may have once fit together.

Early history

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

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]."

Writing in 1889, Alfred Russel Wallace remarks "It was formerly a very general belief, even amongst geologists, that the great features of the earth's surface, no less than the smaller ones, were subject to continual mutations, and that during the course of known geological time the continents and great oceans had again and again changed places with each other." He quotes Charles Lyell as saying "Continents, therefore, although permanent for whole geological epochs, shift their positions entirely in the course of ages" and claims that the first to throw doubt on this was James D. Dana in 1849.
In his Manual of Geology, 1863, Dana says "The continents and oceans had their general outline or form defined in earliest time. This has been proved with respect to North America from the position and distribution of the first beds of the Silurian - those of the Potsdam epoch. … and this will probably prove to the case in Primordial time with the other continents also". Dana was enormously influential in America - his Manual of Mineralogy is still in print in revised form - and the theory became known as Permanence theory.
This appeared to be confirmed by the exploration of the deep sea beds conducted by the Challenger expedition, 1872-6, which showed that contrary to expectation, land debris brought down by rivers to the ocean is deposited comparatively close to the shore in what is now known as the continental shelf. This suggested that the oceans were a permanent feature of the earth's surface, and did not change places with the continents.

Wegener and his predecessors

The hypothesis that the continents had once formed a single landmass, called Pangaea, before breaking apart and drifting to their present locations was first presented by Alfred Wegener to the German Geological Society on 6 January 1912.Although Wegener's theory was formed independently and was more complete than those of his predecessors, Wegener later credited a number of past authors with similar ideas:^[ Franklin Coxworthy (between 1848 and 1890), Roberto Mantovani (between 1889 and 1909), William Henry Pickering (1907) and Frank Bursley Taylor (1908). Eduard Suess had proposed a supercontinent Gondwana in 1885 and the Tethys Ocean in 1893 from a sunken land-bridge/ geosyncline theory point-of-view, though. John Perry had written an 1895 paper proposing that the earth's interior was fluid, and disagreeing with Lord Kelvin on the age of the earth...................


 http://en.wikipedia.org/wiki/Continental_drift
 https://www.youtube.com/watch?v=_5q8hzF9VVE