Theory of Continental Drift

The theory of continental drift is one that has been explored and examined by many scientists, but when one speaks of this theory, the German scientist Alfred Wegener comes to mind. His theory states that approximately 300 years ago, all of the continents were one large mass of connected land called Pangaea (figure 1), and over time they split apart, the separate pieces of lithosphere gradually moving over the asthenosphere. Even now, those plates are still slowly shifting apart from each other because of activity at divergent plate boundaries.

Although Wegener had many pieces of evidence to support his theory, several are incorrect. However, many of them are very plausible. Firstly, when one looks at a current world map, the shapes of continents (ie. South America and Africa) could be moved together to all fit together like a jigsaw puzzle. This is evidence for the fact that Pangaea once existed in a sense that it shows how the landforms may have previously fit together to form one super-continent. Likewise, geological structures such as the Appalachian mountains in North America, and the Scottish Highlands are very similar in composition, which leads one to believe that they were once physically connected and have simply broken apart. Another piece of evidence is that fossils of tropical plants have been found in areas such as Spitsbergen, an island in the Arctic ocean. Because these types of plant life could not grow in such a cold climate, this proves that the Arctic was once located somewhere nearer to the equator where tropical plants could grow healthily. In addition to this, other areas have been found through examination of rocks to have significantly different climates than they may have before, namely the once super-continent composed of Africa, Antarctica, Australia, and India which was supposedly once located near the South pole of the Earth. Similarly, glacial sediments still exist in areas in and around South America and Africa which also supports the fact that the continents were once located at different places on the Earth itself. In this situation, it would be proved that South America and Africa were both situated closer to the South pole than near the equator where they reside now. Other evidence relating to the connection of South America and Africa lies in the fossils of plants and animals on both continents. This shows that when the continents were all physically connected, the animals and plants would have existed on the land where the land has split. Specific examples of animal life that lived on both South America and Africa are several species of earthworms. Thus, all of the previously stated points are evidence that the continental crust that we reside on today was once attached to other large pieces of land.

However, since Wegener was not a geologist, not all of his points were valid. He made many errors when writing his theory simply because he was not educated in the geological facts pertaining