Wegener, Alfred (1880–1930)

Alfred Lothar Wegener, a brilliant interdisciplinary scientist born in Berlin (Germany), was a meteorologist, geophysicist, and Arctic explorer who proposed the theory of “continental displacement,” or what later was called “continental drift.” According to this theory, the continents were once united into a single protocontinent, which he called Pangea. Over time Pangea broke up, and the pieces drifted apart into their present positions. Wegener died in 1930 when he was lost in a blizzard during an expedition to the Greenland icecap.

[Page 1425]Alfred Wegener studied the natural sciences at the University of Berlin. He became interested in climatology and joined the 1906–1908 expedition to Greenland to study polar air circulation. In 1911 he published Thermodynamik der Atmosphäre, a standard textbook dedicated to the science of weather, and in 1926 he accepted a professorship in meteorology at the University of Graz (Austria). Although most of Wegener's life was spent in the study of the climates of the present and the past, his most notable scientific contribution was his hypothesis of continental drift. In 1915, after his participation in World War I, he published his continental drift theory in Die Entstehung der Kontinente und Ozeane, translated into English in 1924 as The Origin of Continents and Oceans

Early 20th-century geologists viewed continents as fixed features that could rise and fall, but not move sideways. Given the difference in density between continents and the deep-sea floor, Wegener proposed that the continents floated somewhat like icebergs in the water. He believed that Pangea originated near the South Pole, and the centrifugal force of the earth's rotation caused its breakup 300 million years ago and the drifting of the resulting fragments toward the equator. The idea of a primitive Pangea arose with Wegener's observation that most of the continents seem to fit together like a jigsaw puzzle. For example, the West African coastline and the east coast of South America provide good evidence of that hypothesis. Searching for further evidence, Wegener found many similarities between the fossil record and paleoclimate between Africa and Brazil; Europe and North America; and Madagascar and India, today separated by oceans but previously united in the Pangea supercontinent.

The continental drift theory remained controversial until the 1960s, when the geologist Harry Hess proposed that the movement of the continents was a result of the existence of mantle convection currents. Geologists now call this process the plate tectonic theory. According to this view, the plates are composed of continents and ocean floor, and float on the asthenosphere. The oceanic ridges are divergent plate boundaries where the rising of magma has created new crust. At the areas where plates have collided, great mountain ranges such as the Himalayas and the Andes are formed.

Wegener's hypothesis was incorrect in certain aspects. For example, today we know that the continents are attached to the plates and do not move independently of them, and that mantle convection is responsible for the breaking and dispersal of these plates. Nevertheless, the continental drift theory can be regarded as a forerunner of modern and paradigmatic plate tectonics theory, and Wegener as an earth science visionary.

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