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Continental Drift

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Introduction

Katherine Trigg 11RMi Continental Drift In these times the theory of Continental Drift is common knowledge to almost any educated person. The knowledge that the continents are slowly moving, is almost presumed knowledge to almost everyone, however this was most definitely not always the case. The theory of Continental Drift was first introduced 100 years ago by a scientist named Alfred Wegener. Wegener first became interested in the concept of continental drift when he came across a scientific paper that listed fossils of identical plants and animals that had been found on opposite sides of the Atlantic. Wegener became intrigued by this information and sought out to find greater pieces of evidence to support his theory, that at one point in time the continents were not separated by these large oceans that we know to be there today. Wegener began to examine rocks from either side of the Atlantic. He noticed that in many cases the rocks that he examined in South Africa were similar if not exactly the same as those he examined in South America. ...read more.

Middle

With this technology accurate maps of the ocean floor could be drawn. It was by using this technology that range of mountains was discovered running down the middle of the Atlantic Ocean. This range of mountains extended for approximately 60,000km underneath the oceans, around the Earth's surface. Wegener was not the first to suggest that the continents had once been connected, but he was the first to present extensive evidence from several fields. However Wegener's theory of Continental Drift was not accepted by many scientists at all. The reactions to Wegener's theory were almost uniformly hostile and often exceptionally harsh. Even after Wegener's extensive research and evidence, he still could not explain how the continents had moved as he believed and so therefore his theory was dismissed by many. It was not until the late 1950s that Wegener's concept of continental drift was revived. The concept was revived due to further exploration of the ocean floor. It was discovered that there were many differences between the Continental Crust and the Oceanic Crust. ...read more.

Conclusion

It was when scientist discovered this that they could finally conclude that new land was being formed along this range of mountains in the Atlantic Ocean. As scientist explored the valley floor of the Mid Atlantic Ridge they also discovered what are known as Hydrothermal Vents, or are sometimes referred to as Hot Springs. These vents proved that there was volcanic activity. Transform faults were also discovered along the Mid Atlantic Ridge. Transform faults occur when different ends of the oceanic crust move apart at different speeds, and cracks form along the earths crust. This is another indication that the oceanic crust is moving, and that new land is being formed. There was however one fault in Wegener's theory. Continents do not plough through the ocean floor. Instead, both continents and ocean floor form solid plates, which "float" on the asthenosphere layer, and due to the underlying rock being under such tremendous heat and pressure it behaves as an extremely viscous liquid. With all this new evidence being discovered, Wegener's theory was finally accepted by all scientists. It has been proven that South American and South Africa were once joined, as were India and Antarctica. And that 255 million years ago, the super continent Pangaea did exist. ...read more.

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