Wegener and his predecessors[edit]
Alfred Wegener
The speculation that the American continents had once formed a single landmass with Europe and Asia before assuming the present shapes and positions was suggested by several scientists before Alfred Wegener's 1912 paper.[13] 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:[14][15] Franklin Coxworthy (between 1848 and 1890),[16] Roberto Mantovani (between 1889 and 1909), William Henry Pickering (1907)[17] and Frank Bursley Taylor (1908).[18] In addition, Eduard Suess had proposed a supercontinent Gondwana in 1885[19] and the Tethys Ocean in 1893,[20] assuming a land-bridge between the present continents submerged in the form 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 age of the earth.[21]
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; Wegener noted the similarity of Mantovani's and his own maps of the former positions of the southern continents. In Mantovani's conjecture, through volcanic activity due to thermal expansion this continent broke and the new continents drifted away from each other because of further expansion of the rip-zones, where the oceans now lie. This led Mantovani to propose an Expanding Earth theory which has since been shown to be incorrect.[22][23][24]
Continental drift without expansion was proposed by Frank Bursley Taylor,[25] who suggested in 1908 (published in 1910) that the continents were moved into their present positions by a process of "continental creep".[26][27] In a later paper he proposed that this occurred by their being dragged towards the equator by tidal forces during the hypothesized capture of the moon in the Cretaceous, resulting in "general crustal creep" toward the equator. Although his proposed mechanism was wrong, he was the first to realize the insight that one of the effects of continental motion would be the formation of mountains, and attributed the formation of the Himalayas to the collision between the Indian subcontinent with Asia.[28] Wegener said that of all those theories, Taylor's, although not fully developed, had the most similarities to his own.[clarification needed] In the mid-20th century, the theory of continental drift was referred to as the "Taylor-Wegener hypothesis",[25][28][29] although this terminology eventually fell out of common use.[30]
Alfred Wegener first presented his hypothesis to the German Geological Society on January 6, 1912.[13] His hypothesis was that the continents had once formed a single landmass, called Pangea, before breaking apart and drifting to their present locations.
Wegener was the first to use the phrase "continental drift" (1912, 1915)[13][14] (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 caused this drift. His suggestion that the continents had been pulled apart by the centrifugal pseudoforce (Polflucht) of the Earth's rotation or by a small component of astronomical precession was rejected as calculations showed that the force was not sufficient.[31] The Polflucht hypothesis was also studied by Paul Sophus Epstein in 1920 and found to be implausible.