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Have you ever noticed how some of the continents and land masses of Earth seem to fit together like pieces of a puzzle? The coastlines of North America and Europe seem to match, and the shorelines of South America and Africa look like they were just recently torn apart from each other. Is this a coincidence, or could there be a reason for this observation?

Alfred Wegener photo obtained from USGSAlfred Lothar Wegener (1880-1930), a German astronomer and meteorologist, noticed these same patterns. While he was recovering from a World War I injury, he had time to develop some ideas about what could have happened. His theory, called Continental Drift, said that the continents had all been together in one large land mass at one time and had since "drifted" apart to where they are today. His theory had some very strong points, and some very weak points.

For example he realized that not only do the shapes of the continents seem to match, but there are similar fossils and rock types of the same age at corresponding places on each coast. Also, there is evidence of dramatic climate changes in the rock and fossil record. For example, fossils of ferns that usually grow near the equator have been found in Antarctica! These observations and facts supported his ideas well.

On the other hand, he could not explain what types of enormous forces could be strong enough to move such large masses of rock that were part of a seemingly solid Earth. His best explanation was that the continents just plowed through the crust beneath them like a boat plows through the water, pushing the ground aside as it goes. What do you think... does that make much sense? Not really!

At the time most people thought of Earth as a constant, always looking just like it does now. They also believed it always will look the same. This bias, along with Wegner's weak explanation of the forces involved, caused most of the scientists at the time to reject his ideas. He had a great start, but more evidence was needed.

The complete story can be found from the USGS.
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Updated October 24, 2008 by: Glen Westbroek

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