History

This theory was developed from a theory of continental drift, which was presented in 1912 by a German meteorologist named Alfred Wegener. Wegener proposed that initially, all the present continents were one supercontinent called Pangaea and that it split up about 200 million years ago to form the present continents.

Various evidences supported this theory. According to Wegener, some of the continental coastlines appeared to fit together. The western coast of Africa fit together with the eastern coast of South America. Fossils of reptiles in Africa and South America matched. There was the presence of an identical fossil fern in all the southern continents. There was the presence of coal, which is formed under warm, wet conditions, in Antarctica.

At first Wegener’s theory was rejected. However, evidence supporting the theory gradually accumulated. In the late 1930’s, an American Geologist, David Griggs demonstrated that solid rock, when subjected to high temperatures and pressures, could flow slowly. In the later years between 1940 and 1960, it was shown that the oldest ocean rocks were only less then 150 million years ago, which was evidence that there had been some movements.

In the late 1950’s, it was discovered that most of the earthquakes occur along lines parallel to ocean ridges and trenches. In the later years, discoveries that there were cracks along the ocean floors and that the location of volcanoes and earthquakes coincided with the locations of the cracks. Through other discoveries and experiments, scientists became more convinced with Wegener’s theory.

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