Plate Tectonic Theory
The continental drift theory stated that the world was formed of a single continent that separated and drifted apart to form 7 continents that exist today. According to Alfred Wegner, a German meteorologist, the continents were comprised of light rocks that rested on heavy crustal material. According to Wegner, the continents were previously a single large continent that broke apart and drifted along the floor of the ocean up to wear the continents are located today. While Wegner used the fit of the 2 continents that had already been mentioned, he also used lithological similarity and fossil distribution as evidence.
Wegner’s hypothesis received criticism from his peers. According to Wilson (1996), some rubbished the idea that continents would move about through solid rock. There were those who held the belief that basins and continents were fundamentally unchanged in their relative configuration and position since their formation. Then there were others who held the belief that as the solid earth gradually contracted, the ocean floor turned into dry land which in turn became the floor of the ocean. However, some of Wegner’s arguments have been found to be correct. There are a number of types of evidence that support the plate tectonic theory.
First, many continents are shaped in a way that they appear to be separated pieces of a jig-saw puzzle. Second, when fossils found along the continental edges are compared, they seem to fit together and this is a suggestion that the similarities in the species are an indicator that the continents might have been joined sometimes in the past (Dawson, 1998). Third, a large amount of volcanic, seismic and geothermal activity can be found along the conjectured plate boundaries. These are some of the evidences that support the plate tectonics theory.
References
Dawson, J.P. (1998) Plate Tectonic Theory. Retrieved on 24 Nov. 2013 from http://www.drjpdawson.com/pelgnet/pelchap3/Chap3.html
Wilson, J.T. (1996) Continental Drift. Retrieved on 24 Nov. 2013 from http://www.platetectonics.com/article.asp?a=18
