By Sophie Lichtenstein
Between 298.9 and 251.9 million years ago, all the continents on Earth existed as one massive continent called Pangaea. After this geologic period, called the Permian, Pangaea drifted apart to form the Atlantic and Pacific oceans and the positioning of the continents that we know today. This movement, caused by tectonic plate activity fueled by convection currents in molten rock in the Earth’s mantle, is incredibly slow. Large changes like formation and dissolution of supercontinents takes hundreds of millions of years. It is believed that there have been seven supercontinents throughout Earth’s 4.5 billion years of history, with Pangaea being the most recent.
The idea of Pangaea’s existence is part of plate tectonic theory, which was developed in the 1960s and explains many geological phenomena like volcanoes, earthquakes, and mountain buildings. Plate tectonic theory, and the continental drift theory, can also support the theory of evolution, as plant and animal remains of the same species appear on the coastlines of continents separated by entire oceans. One example of this is the Mesosaurus, a reptile whose remains have been found primarily in Southern Africa and Eastern South America. The Mesosaurus could not have swam between the two continents, supporting the continental drift theory and suggesting that the Mesosaurus lived in the area in which there formerly was a junction between those two continents. Similarly, glacial deposits from 300 million years can be found in Antarctica, Africa, South America, India, and Australia, supporting the idea that these land masses were once joined and covered by one large ice sheet.
While in a single human lifetime there are no significant observable changes in the formation of the continents, tectonic plate movement is still ongoing. Scientists predict that the next supercontinent, called Pangaea Ultima, is expected to form in about 250 million years. When this happens, the formation of many new volcanoes and increase of carbon dioxide levels may make the Earth uninhabitable. Temperatures are also predicted to rise, and a mass extinction will occur. However, some scientist believe that life may be able to be sustained under these conditions, and the massive interior deserts in Pangaea Ultima have existed in prior supercontinents.