Map of the east coast of South America and west coast of Africa
The theory of continental drift was accepted in the 1960s. Until then, there was a lot of disagreement between scientists. Some believed that the continents were immobile, while others believed that they had travelled great distances over time.
The idea that gigantic masses, such as the continents, could move thousands of kilometres was hard to believe, but there were many signs that they did. The most suggestive of these was that the east coast of Africa and west coast of South America seemed to fit together.
The German geophysicist and meteorologist, Alfred Wegener, was the first to find proof to explain why the coasts of these continents look like they could fit together and to demonstrate that the continents were joined together in the past. He discovered that the continental shelf of each continent fitted together exactly. He also found that mountain ranges had rocks of the same age and identical fossil evidence in both continents.
In 1912, he proposed his hypothesis of continental drift. According to his hypothesis, 225 million years ago, all the continents were joined together as one large supercontinent called Pangaea, which means the whole Earth. Over a very long period of time, the continents drifted apart to the positions they are in today.
Wegener wrongly believed that the continents were made of a light crust that could slide over the ocean floor, as it was a continuous and denser layer. Today we know that the surface layer of the Earth, the lithosphere, slides over the fluid material in the mantle.
Wegener found evidence to prove that the continents were once joined together:
Wegener did not find evidence to explain the movement of the continents and his theory was rejected. Half a century later, Wegener's theory was finally accepted due to advances in technology that improved our knowledge of the Earth's interior, the ocean floor and the distribution of earthquakes and volcanoes.
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