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Continental Drift Hypothesis-Theory of Plate Tectonics
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Continental Drift Hypothesis
Alfred Wegener hypothesised that all the 7 continents were once part of 1 giant super continent called Pangaea and over the course of over 200 million years the continents drifted to their current locations -
Evidence Of Continental Drift
Fossils of the same organism were found on the coasts of South America and Africa, and the fossils could only be in these locations because these 2 continents were together, it would be imposible for the foosils to cross the atlantic ocean.
Matching rock types were found in several mountain belts and when the Appalachan Mountains and the mountain belt in Scandinavia when combined looks like 1 big mountain belt during Pangaea. Glacial sheet deposits were found dating back 220 milion years in area -
Evidence Continued
Glacial sheets deposits were found dating back 220 million years in souther tropical areas today proving that these warm tropical areas were once close to the south pole and the land covered in ice sheets. -
Rejection of Wegener's Hypothesis
Although Wegener had valid evidence, he could not explain the mechanism that moved the continents. He claimed the moons tidal pull was the mechanism, but physicists proved that the energy required by the moon to move the continents would cease Earth's rotation entirely. -
Discovery of the Continent Moving Mechanism
A scientist named Authur Holmes sugested that the mechanism is convection currents. The changing heat of earth's core rising earths plates to rise and sink. This rising and sinking of the plates causes them to move.
.http://www.amnh.org/education/resources/rfl/web/essaybooks/earth/p_holmes.html -
Magnetic Evidence on the Sea Floor
Magnetic imprinnts of the ocean floor have been found on both sides of mid ocean ridges showing swithed several times while the continents drifted. The more of these imprints there were the more time past.
http://www.earthage.org/EarthOldorYoung/Continental_Drift_and_the_Age_of_the_Earth.htm -
Theory of Plate Tectonics
The Theory of Plate Tectonics proved the Wegener was correct, the continents do move and they are divided into plates.
