Alfred Wegener and Continental Drift

Returning from Greenland Wegener received a position at the University of Marburg where he lectured on meteorology and astronomy. He was well liked and known for his ability to explain difficult concepts with a simple clarity. In 1911, Wegener took his lectures on meteorology and published them in a book Thermodynamik der Atmosphäre (The Thermodynamics of the Atmosphere) which became the new standard textbook on meteorology in Germany.

During this same year, 1911, Wegener came across information in the library at the University of Marburg that described identical plant and animal fossils found in South America and Africa. Wegener became intrigued by this knowledge and soon found more cases of identical fossils found across both continents. He also found evidence of large geological features that could be linked, including the Appalachian Mountains in North America with the Scottish Highlands. Wegener took these facts and first presented his early theory at a meeting of the Geological Association in Frankfurt in 1912. Wegener returned to his Greenland research and in 1914 was drafted into the German Army. He was wounded and while recuperating he was able to use the time to flesh out his expanding theory of continental drift. The culmination of his research was published in a book entitled Die Enstehung der Kontinente und Ozeane (The Origin of Continents and Oceans) in 1915. Because of the war Wegener's theory was not read except within Germany, but by 1922 his book had been translated into English, French, and Spanish and a firestorm was unleashed in the geologic community.

Wegener's book first eliminated the prevailing theory that massive land bridges had once existed that connected the various continents. (This had been the main way of explaining the identical plant and animal fossils.) He pointed out that the continents are made of less dense rock (granite) than the oceans (made of basalt). Wegener proposed that the continents floated on an ocean of basalt, like icebergs floating in water. Wegener's proof of this was the concept of isostasy; that the continents move up and down to maintain equilibrium. He used the sinking of the Northern Hemisphere during the last Ice Age and their continual rise in the past 10,000 years as an example of how the continents "floated" on the ocean of basalt. Wegener reasoned that if large, continent-sized land bridges had existed, and then forced to the ocean floor, they would have 'bobbed-up' when this force

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