Alfred Wegener : biography
Alfred Lothar Wegener ( – ) was a German polar researcher, geophysicist and meteorologist.
During his lifetime he was primarily known for his achievements in meteorology and as a pioneer of polar research, but today he is most remembered for advancing the theory of continental drift (') in 1912, which hypothesized that the continents were slowly drifting around the Earth. His hypothesis was controversial and not widely accepted until the 1950s, when numerous discoveries such as palaeomagnetism provided strong support for continental drift, and thereby a substantial basis for today's model of Plate tectonics. Wegener was involved in several expeditions to Greenland to study polar air circulation before the existence of the jet stream was accepted. Expedition participants made many meteorological observations and achieved the first-ever overwintering on the inland Greenland ice sheet as well as the first-ever boring of ice cores on a moving Arctic glacier.
Continental drift theory
Alfred Wegener first thought of this idea by noticing that the different large landmasses of the Earth almost fit together like a jigsaw puzzle. The Continental shelf of the Americas fit closely to Africa and Europe, and Antarctica, Australia, India and Madagascar fit next to the tip of Southern Africa. But Wegener only took action after reading a paper in 1911 and seeing that a flooded land-bridge contradicts isostasy., cited in Wegener's main interest was meteorology, and he wanted to join the Denmark-Greenland expedition scheduled for mid-1912. So he hurried up to present his Continental Drift hypothesis on January 6, 1912. He analyzed either side of the Atlantic Ocean for rock type, geological structures and fossils. He noticed that there was a significant similarity between matching sides of the continents, especially in fossil plants. His hypothesis was thus strongly supported by the physical evidence, and was a pioneering attempt at a rational explanation. From 1912, Wegener publicly advocated the theory of "continental drift", arguing that all the continents were once joined together in a single landmass and have drifted apart. He supposed the cause might be the centrifugal force of the Earth's rotation ("") or the astronomical precession. Wegener also speculated on sea-floor spreading and the role of the mid-ocean ridges, stating: the Mid-Atlantic Ridge ... zone in which the floor of the Atlantic, as it keeps spreading, is continuously tearing open and making space for fresh, relatively fluid and hot sima [rising] from depth. However, he did not pursue these ideas in his later works.
In 1915, in The Origin of Continents and Oceans ('), Wegener published the theory that there had once been a giant continent, he named "'" (German word meaning "origin of the continents", in a way equivalent to the Greek "Pangaea", meaning "All-Lands" or "All-Earth") and drew together evidence from various fields. Expanded editions during the 1920s presented the accumulating evidence. The last edition, just before his untimely death, revealed the significant observation that shallower oceans were geologically younger.
In his work, Wegener presented a large amount of very strong evidence in support of continental drift, but the mechanism remained elusive. While his ideas attracted a few early supporters such as Alexander Du Toit from South Africa and Arthur Holmes in England, the hypothesis was generally met with skepticism from largely conservative scientists, who were resistant to any change in the status quo. The one American edition of Wegener's work, published in 1925, was received so poorly that the American Association of Petroleum Geologists organized a symposium specifically in opposition to the continental drift hypothesis. Its opponents could argue, as did the Leipziger geologist Franz Kossmat, that the oceanic crust was too "firm" for the continents to "simply plough through", a suggestion which ignored the plasticity of all rocks at depth and at high temperatures and pressures. The comment also ignored the vast time-scale over which continental drift has occurred, effectively the total age of the earth of about 4.5 billion years.
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