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Continental Drift - the evidence that supports the theory.

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Introduction

´╗┐Continental Drift Fact or Fiction? First proposed by Alfred Wegener the meteorologist, the theory of continental drift supports the belief that the Earth's continents once were a single land mass. This land mass, which was named "Pangaea", broke up, and its various parts drifted away from one another. Centuries ago, trips around the world from travellers showed out lines from every continent around the world. Later on, early mapmakers wondered why these continents fit together so well. Early geologist thought at first that the continents had started off in their places they laid in the present day. However, a meteorologist constructed a theory that would change the way people would look at the world. The Theory of Continental Drift is a theory that proves that the continents were once joined together making only one single landmass. This theory was proposed by a meteorologist by the name of Alfred Wegener. His theory states that the continents were once one and have drifted apart. Wegener named this land mass ?Pangaea?, which translates ?All Lands? Then he gathered evidence from around the world from landforms, fossils, and climate. He then gathered his evidence and put it in a book titled ?The Origin of Continents and Oceans? which was published in 1915. But Wegener?s theory was rejected because he could not provide evidence on the force that moved the continents. The Earth has a magnetic field that causes a compass needle to always point toward the North magnetic pole, currently located near the rotation pole. ...read more.

Middle

An example of this would be that in places like South America and Africa the same animal fossils have been found which could only have happened if they were originally joined. Palaeoclimatology is the study of changes in climate taken on the scale of the entire history of Earth. Parts of all the continents in the Southern Hemisphere were covered by glaciers in their geological past. Glaciers grind and smooth the rocks across which they move, and leave grooves where rocks that were caught in the ice grated over the bottom rocks. When the ancient scour marks on the continents in the Southern Hemisphere are studied, it appears as if the ancient glaciers were formed in the oceans and moved towards the land. But no glacier we know of functions in this way. Glaciers usually form in high-lying regions and then move slowly downwards in the direction of the oceans. However, if we could move the continents back to recreate Gondwana, all ancient glacier parts would fit neatly into one another without being separated by oceans. While the ancient fossils on different continents were often similar or identical, the exploring naturalists were finding out that living plants and animals on the different continents were often very different. The naturalists were discovering whole new groups of animals and plants on nearly every island and continent they visited. Most biological species seemed to be unique to the region or continent in which they were found. ...read more.

Conclusion

Confounded by his critics on the evidence for drift in the geological past, Wegener turned to geodetic data in the form of longitude measurements around Greenland to establish that continents may be drifting today. Since then, phenomenal advances have occurred in geodetic measuring techniques. Many geodetic methods today utilise the technologies of space. They include very long base line interferometry with radio waves from distant quasars, laser ranging and the GPS. All yield highly precise and repeatable measurements. In conclusion, it was an important day in 1912 when Wegener proposed his theory. Le Grand views the subsequent developments related to the idea of continental drift as the stuff of myth and legend. In one inspired paragraph, he equates continental drift with Cinderella, and its critics with her vain stepsisters. He compares the geophysicists of the 1950s and early 1960s with Cinderella?s Fairy Godmother who waved the Magnetic Wand. Cinderella went to the Ball and married the Prince represented by the seafloor spreading hypothesis and the plate tectonics theory. The history of science is replete with instances where ideas popular in one period were discarded subsequently. Thus I cannot end in the normal style of fairy tales by saying, .The idea of continental drift lived happily ever after.. Changes may be anticipated. How and when, I can.t say. But, as of now, GPS results provide a reasonable basis to infer that continents drift and all other earth sciences observations may be reconciled in light of this fact. ...read more.

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