Plate Tectonics and People

Alfred Wegener

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Biographical Information Alfred Wegener was born on November 1, 1880 in Berlin. He was the son of an evangelical minister. Ironically, Wegener was not schooled in geology. He earned his doctorate in Astronomy. However, Wegener's true passions were in the fields of meteorology and arctic exploration. Wegener married Elsa Koppen, daughter of meteorologist Wladimir Peter Koppen in 1913. He succeeded Koppen as the director of the Meteorological Research Department of the Marine Observatory at Hamburg after World War I. In 1924, he became the chair of the meteorology and geophysics department at the University of Graz in Austria. Wegener was somewhat of an adventurous spirit. One of his primary ambitions was arctic exploration, particularly in Greenland. Wegener took three trips to Greenland in his lifetime. His second trip in 1912 featured the longest crossing of an ice cap ever taken at the time and resulted in the publication of multiple glaciological and meteorological volumes. Wegener died in 1930 of a heart attack caused by overexertion while leading his third expedition in Greenland. Specific contributions to plate tectonic theory- Continental Drift One could say that Alfred Wegener is the father of Plate Tectonic Theory. Wegener noticed that the east coast of South America lined up almost perfectly with the west coast of Africa. This was certainly not a new observation. In 1620, Francis Bacon called attention to the similarities in the continental outlines of eastern South America and western Africa. In 1858, Antonio Snider-Pelligrini suggested that the continents had been moved by the biblical flood. Wegener's assessment sticks out for two reasons. The first reason Wegener's hypothesis holds weight is that Wegener used geological evidence to back his claim that Africa and South America were at one time connected. The collection of maps, rock formations, and fossil records provided the evidence Wegener needed to connect South America to Africa. Most people observed the apparent surface similarities of the two coasts, but Wegener was the first to look into how the continents fit together at their respective continental shelves. The continental shelf is the shallow ocean lying off the coast of a continent. Wegener compared the outlines of South America's eastern continental shelf with Africa's western continental shelf. It turned out that the continental shelves of the two continents fit together even better than the observable coastlines. This was the first step for Wegener connecting the two continents (scientifically). Next, Wegener used geologic and fossil records to further support his claim. Wegener noticed that fossils from a small lizard from the Paleozoic Era (approx. 270 million years ago) appeared in only two places on Earth. Fossils for the Mesosaurus are found only in southern Africa and eastern South America. The Mesosaurus was a freshwater animal and would be incapable of crossing the Atlantic Ocean. This would lend credence to the belief that Africa and South America were connected 270 million years ago when the Mesosaurus roamed the Earth. Wegener also tried to provide a viable mechanism for continental movement, but this posed problems. The leading theory of the time was that the earth formed in a molten state. The heavy elements sunk to the core while the lighter elements floated to the surface and cooled to form the crust. The thought was that mountains and oceans were caused by shrinkage. That is, the earth contracted as it cooled. Wegener discredited this hypothesis on the grounds that mountains and valleys don't form in uniform patterns. He also observed that the earths crust had two basic elevations. These elevations were the ocean abyss and the contiental crust. This observation would not provide Wegener with the engine for continental drift, but it would be a pivotal point of study for future scientists and would lead to theories in sea floor spreading and, ultimately, plate tectonic theory. Other interesting scientific contributions 1.) Alfred Wegener observed the apparent wandering of earth's magnetic pole. Wegener attributed this to the movement of the poles followed the approximate path of the movement of his continents. Not only did this discovery provide evidence of continental drift, it also was an early example of the study of paleomagnetism. 2.) Wegener also used paleo climatology to help prove his theories. He used fossil records to study climate change through geologic time. Paleoclimatology is currently a hot field in science, as scientists attempt to determine the potential effects of greenhouse gas emissions caused by human activity. Other cool stuff you should know 1.) In 1906, Wegener and his brother Kurt set a world record for uninterrupted balloon flight at 52 hours. 2.) Geology and paleoclimatology, and paleomagnetism were the sciences that Wegener used to formulate his Continental Drift hypothesis, but Wegener was not officially schooled in any of them. Wegener's doctorate was in Astronomy. However, Wegener's livelihood came mostly from the field of meteorology. 3.) Wegener was a lifelong smoker. His death in 1930 of heart failure due to overexertion is often attributed to his smoking habit. 4.) Continental drift did not gain popular acceptance until the 1960s. One issue was Wegener's lack of geoscience credentials. Another issue that hurt the hypothesis was the mechanism that Wegener proposed to initiate continental drift. Wegener believed that tides in the crust caused continental drift, but this idea was defeated by Harold Jeffries who proved that these proposed tides were not strong enough to cause continental drift. He also pointed out that Wegener's hypothesis did not account for verticle movement in the earth's crust. It was not until Harry Hess proposed the theory of sea floor spreading based on mid ocean ridges that the continental drift theory would get its engine. Bibliography 1. 2. 3. Hallam, A. Alfred Wegener and the Hypothesis of Continental Drift. Scientific American. 232(2). 1975 pp 88-97