What Is The Link Between Continental Drift, Plate Tectonics, And The Development Of Earthquakes And Volcanoes?
What Is The Link Between Continental Drift, Plate Tectonics, And The Development Of Earthquakes And Volcanoes?
Steven Marlow
Before thinking about how continental drift, plate tectonics and the development of earthquakes and volcanoes link together, it is important to understand what exactly each are.
The theory of continental drift entered mainstream thought around about 1915, when an Austrian Meteorologist published a book imaginatively called “continental drift“. Its discovery was mainly brought about by the fact that west Africa and east South America seem to fit together perfectly. After some research, it was found that South America and Africa share a lot of similarities buried beneath the soil millions of years ago; such as fossils and soils. Fossils of many dinosaurs dating back to a certain period can be found in Africa and South America in the same layer of rock beneath the surface, suggesting they existed at the same times on the two continents. Evidence of ice sheets, dating from the ice age in the carboniferous period roughly 290 million years ago, beneath the soil in the two continents fits together perfectly, like a jigsaw puzzle; as do the coastlines. Deposits of many minerals on the two continents, such as rare violet quartzes found in South Africa and Brazil from the Devonian period, occur in shapes that seem to be cut in half; if the two continents were joined this would not appear to be the case. This has been taken as proof that the two continents were once linked. However there is evidence supporting the previous linkage of other land masses, and deposits in the soil which suggest that it could not have possible always existed at the current latitude the continent is situated in now. For example there are many carboniferous coal deposits in regions that are now temperate, that contain plant fossils of plants that belong to a rainforest. Geological structures which were found in a number of areas suggest that in prehistory they were joined - folds dating back to a certain mountain building phase were found in the USA, Wales, and the Urals. Rare glossopteris leaf fossils in coal deposits were found in South America, South Africa, India and Australia. If the areas with these fossils were looked at closely the bird’s-eye-view suggests that they were one adjacent. More recently there has been the discovery of paleomagnetism, which won over the staunchest opposes to the continental drift theory. The magnetic pole of the earth is never fixed; it moves from the North to the South pole in cycles over a geological time scale. Certain rocks, most commonly igneous and sedimentary, retain a magnetisation reflecting where the magnetic poles were at the times of the rocks’ formation. Scientists can locate where the poles were at a certain point in prehistory by looking where the magnetisation of certain rocks of a known age is pointing. This process is repeated on magnetised rocks throughout the world, which leads to the knowledge of the path that the poles took. This technique was then done on rocks in South America and Africa, and as the magnetisation of the rocks was almost parallel, it proves that the poles at the time of that rock’s formation were almost in the same place in relation to the two continents, which conclusively proves that in prehistory they were adjacent. There is a lot more evidence; too numerous to list here of proof that all the continents were joined as one in the past, called Pangaea. In the 1960’s the theory of continental drift became to be widely accepted throughout the world, and has since led us on to some interesting discoveries.
