Continental drift is happening. Discuss the evidence

Continental drift is defined as the gradual movement of continents across the Earths surface through geological time. As early as 1620, Francis Bacon noted the jigsaw-like fit between the east coast of South America and the west coast of Africa. However, it was in 1912 when a German meteorologist, Alfred Wegener, published his theory that all the continents were once joined together in one large supercontinent, which was named Pangaea. Wegeners theory of continental drift combined information from several subject areas, examples include: maps, biology, geology and climatology. Be that as it may, specialists in those disciplines rejected his ideas partly because he was not regarded as an expert himself, but mainly because he could explain how solid continents had changed their position. Wegener could never come up with an underlying reason for the motion of the continents. The theory of continental drift eventually evolved into the modern theory of plate tectonics. This holds that the lithosphere (or the Earth's crust) is made up of numerous plates that literally float on the underlying liquid asthenosphere. The motion of the plates and resulting activity at their edges to form mountains, trenches, and volcanoes explains the planet's topography.

The first piece of evidence that really inspired Wegners quest to explain Earths geology was a map of the continents that showed the interlocking fit of Africa’s and South Americas shoreline. Using these maps, Wegener then questioned as to why these coastlines fitted so precisely. He came up with the theory that in the remote past (200 million years ago) they were part of a larger super continent (Pangaea) that then spilt apart via sub-oceanic forces which sent the landmasses wandering around the globe. Here is a picture that shows how all of the continents perfectly fit into each other. Taking into account all of Wegeners research on the puzzle like structure of all of the continents, it is hard to disagree with his theory that there was such thing as a supercontinent

From looking at these maps it led Wegener to predict that if these coastlines were connected, then the geology at the corresponding positions along the coastline should correlate. As a result of this prediction, Wegener began to study the stratigraphy of different rocks and mountain ranges, again looking more specifically at the east coast of South America and the west coast of Africa. Seemingly he discovered that the rock layers ‘fitted’ just as clearly as the maps had previously showed. With both coastlines showing that the oldest layers of rock were granite, then slate and finally it was sandstone. However, the final two layers of the coastline were different, but this is because a lot has changed in the 80million years that they have been separated. Moreover, South America and Africa weren’t the only continents with similar geology. Wegener discovered that the Appalachian Mountains of eastern United States were geologically related to the Caledonian Mountains in Scotland as well as the Appalachian Mountains being nearly identical to the Atlas Mountains of Morocco, because the same process formed them when they were part of the same chain (see picture above).

After looking at the geology of the different coastlines, Wegener began to look at fossilized plants and animals to further support his claim of Continental drift. Again he began to look at two different coastlines of two different continents to see if any of the same fossils could be found. He decided to inspect the fossil of the ancient reptile mesosaurus, a freshwater reptile only one metre (3.3feet) long that could only be found in southern Africa and South America. As a result of the two continents being separated by the Atlantic, it somewhat proved that these animals could not of been able to swim across, but in fact suggested that they were once from a single habitat with many lakes and rivers, adding credence to the belief that Africa and South America were connected 270 million years ago when the Mesosaurus roamed the Earth. Wegener also studied plant fossils from the frigid Arctic archipelago of Svalbard, Norway. These plants were not the hardy specimens adapted to survive in the cold Arctic climate. These fossilised plants were of the tropics, which are adapted to a much warmer, more humid environment. This evidence of the presence of these fossils suggests Svalbard once had a tropical climate. The picture above shows the sites of which the Mesosaur existed in South Americ and Western Africa.

From looking at the information on fossils found around the world, it shows that there are many examples of where the same fossil has been found on separate continents and nowhere else proving that the Mesosaurus wasn’t the only one, thus suggesting that the continents were once joined. Moreover, if continetal drift had not occurred then the alternative explanations would be that the species evolved independently on separate continents – contradicting Darwins theory of evolution, or they swam to the other continent/s in breeding pairs to establish a second population. However, to explain the unusual distribution of fossils in the Southern Hemisphere some scientists at the time proposed there may once have been a network of land bridges between the different continents. To explain the existence of fossils of temperate specied being found in artic rewions, the existence of warm water currents was proposed.

The mechanism of glacial deposit within the southern hemisphere was another idea that supported the movement of the continents. With the continents in their present positions, the depositis seem to indicate that there was erratic glacier motion. Seeing as though when the continets are fitted together, they show a much more smoother motion of the glacier from the southern part of Africa and ther Northern part of Australia outward. Once Wegener had proposed the idea of glacial deposits he collected ancient climate information to confirm his glacial data. For the glaciers to have been present with the continents in ther current positions, much of the world should have been under ice. However, this was not the case. Sedimentary rock examinations showed a change in climates, and the only possible explanations were continental drift or movement of the poles