In 1912, he presented the idea of "continental displacement"-which would later become known as "continental drift"-to explain how the continents moved toward and away from one another throughout the Earth's history. He eventually articulated the idea that all of the Earth's continents were at one time connected into one large supercontinent. In 1911, Wegener also came across several scientific documents stating there were identical fossils of plants and animals on each of these continents. He had noticed, in 1910, that the eastern coast of South America and the northwestern coast of Africa looked as if they were once connected. During his time at the university, Wegener developed an interest in the ancient history of the Earth's continents and their placement. ISBN 0-17-448020-2.Shortly after receiving his Ph.D., Wegener began teaching at the University of Marburg in Germany, and in 1910 he drafted his "Thermodynamics of the Atmosphere," which would later become an important meteorological textbook.
Principles of Physical Geology (1st ed.). "Radioactivity and Earth Movements" (PDF). United States of America: Holt, Rinehart and Winston. Historical perspective, in This dynamic Earth: the story of plate tectonics. Translated from the fourth revised German edition by John Biram. Geologische Rundschau (in German) 3 (4): 276–292. Today geologists say that continents are actually parts of moving tectonic plates that float on the asthenosphere, a layer of partly molten rock. Evidence ĭuring the 1950s, in the mid-atlantic ridge discoveries of sea-floor spreading and magnetic reversal proved that Wegener's theory was real and led to the theory of plate tectonics, though his proposed causes were mistaken. Wegener thought that the forces that moved the continents could be caused by the rotation of the Earth and stellar precession and that same forces made earthquakes and volcanic eruptions. Others argued that Wegener's theory did not explain the forces that would have been needed to move continents to such great distances. Wegener, explained that the ends of each continent could fit together like a puzzle and that over time the continents drifted apart. Some critics thought that giant land bridges could explain the similarities among fossils in South America and Africa. Continental drift was a theory offered by Alfred Wegener in 1912 that hypothesized that all the continents at one time fit together as one land mass. However, most Earth scientists and palaeontologists did not believe Wegener's theory and thought it was foolish. His Principles of Physical Geology, ending with a chapter on continental drift, was published in 1944. He proposed in 1931 that the Earth's mantle contained convection cells that dissipated radioactive heat and moved the crust at the surface. The British geologist Arthur Holmes championed the theory of continental drift at a time when it was unfashionable. Although continental drift explained many of Wegener's observations, he could not find scientific evidence to make a complete explanation of how continents move. Wegener said that because they are less dense, continents float on top of the denser rock of the ocean floor, and move across the ocean floor rock. He believed these similarities could be explained only if these geologic features were once part of the same continent. Also, he said that the rock strata in South Africa and Brazil were similar. For example, he said that there were geological similarities between the Appalachian Mountains in North America, and the Scottish Highlands. Wegener used geologic, fossil, and glacial evidence from opposite sides of the Atlantic Ocean to support his theory of continental drift. The first time was by the mapmaker Abraham Ortelius in the 16th century. The theory had been proposed before, more than once. After the war he mainly did weather work. He was severely wounded in Belgium and transferred to the army weather service. As a reserve officer of the German Army he was called up in 1914 to fight in World War I. Wegener was born in Berlin and in 1904 he earned his PhD in Astronomy at the University of Berlin. Then several discoveries gave evidence of continental drift, and of the actual causes. His hypothesis was not accepted until the 1950s. He also had ideas about why the continents drift, which other scientists thought were impossible. This was the idea that the continents were slowly drifting around the Earth.
He is most notable for his theory of continental drift, which he proposed in December 1912. Commemorative plaque on Wegener's former school in WallstrasseĪlfred Lothar Wegener (1 November 1880 – 13 November 1930) was a German scientist, geophysist and meteorologist. Fossil records suggesting that continents now separated were once together: see Pangaea First known illustration of the opening of the Atlantic Ocean, by Antonio Snider-Pellegrini, 1858.
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