Evaluate How Plate Tectonics Theory Helps Our Understanding of the Distribution of Seismic and Volcanic Events [40 Marks] Essay

1307 WordsNov 9, 20146 Pages
The Earth’s surface is divided into 15 main plates, some continental and some oceanic. Along some of the boundaries that split up these plates the vast majority of all volcanic and seismic events take place. I will demonstrate through the use of various examples over various time periods that the theory of plate tectonics is crucial in order to help our understanding of the distribution of these events. In 1912 Alfred Wegener proposed a theory of plate tectonics. He claimed that each of the present continents was once joined together as part of a super continent called Pangea. He believed this because he saw that in certain areas continents would fit together for example the west coast of Africa fits together with the east coast of South America, therefore they must have moved apart from one central mass. Other evidence was shown to back up this theory such as the fact that glacier derived clays are found in all of the continents in Gondwana forming one half of Pangea, as one striations in rocks of Carboniferous age. Presently they cover half the globe but would form a reasonably sized polar ice cap if Wegener’s theory was true and the globe was reconstructed in his image of how it used to be. Despite Wegener having no concrete proof as to why this was the case his theory was proved to be accurate, physicists had believed that the earths crust was far from strong enough to be able to force itself apart. Arthur Holmes’ work on radioactivity showed that this was not actually the case. The earth was actually much hotter then previously thought and as a result much weaker. This suggested that the mantle could transfer heat by convection currents when solid. These currents could move continents laterally along the earth’s surface. Paleomagnetism further backs this up, it shows that the positions of magnetic north for 200million year old rock in different continents
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