Why do many of the continents appear to fit together like puzzle pieces?
Continental Drift Theory
In 1912, scientist Alfred Wegener proposed the theory of continental drift in order to explain why many of the continents appear to fit together like puzzle pieces into one supercontinent called Pangaea. He dedicated much of his life to gathering evidence to support his theory including look-alike animal and plant fossils, and similar rock formations found on different continents. Because Wegener could not identify the cause of how the continents were actually moving, most geologists of his time completely rejected his idea.
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Evidence Supporting Continental Drift Theory
3. Fossil correlations. Glossopteris was a fern-like plant that lived 250 million years ago. Glossopteris fossils have been found in Africa, South America, Australia, India, and Antarctica that are now separated by vast oceans. Other examples include fossils of the freshwater reptiles Mesosaurus and Lystrosaurus. These fossils have also been found in places now separated by great oceans. Neither reptile could have swum great distances across salt water. Wegener inferred that these reptiles lived on a single landmass that had since split apart called Pangaea.
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4. Evidence from climate changes. As a continent moves toward the equator, its climate gets warmer. As a continent moves toward the poles, its climate gets colder. In either case, the continent carries along with it the fossils and rocks that formed at all of its previous locations. Fossils of tropical plants were found on Spitsbergen, an island in the Arctic Ocean. When these plants lived about 300 million years ago, the island must have had a warm, mild climate. |
Summary of Evidence
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Topic Tips
- Alfred Wegener was a brilliant scientist who gathered evidence to support the idea continents are in motion. This evidence included fossil evidence, rock correlations, and the shapes of continents themselves. Unfortunately, the one thing Wegener was unable to explain was how the continents actually move. This is what we will explore next. How enormous continents can actually move!