Continental drift is a theory that strives to explain how the continents move over time. In 1912, Alfred Wegner proposed that all continents were at one time connected into one large land mass that he called Pangaea. Over time, the shifting of tectonic plates caused the land mass to be split into the current locations of today's continents. Convection currents below the Earth's mantle cause the tectonic plates to spread apart from one another in opposite directions. The most noticeable location of this "seafloor spreading" occurs along the Mid-Atlantic Ridge.
Alfred Wegner’s theory of continental drift helps explain why very similar organisms, fossils, and rock formations are found in continents found on opposites sides of the world. For example, fossils of the reptiles Cynognathus and Mesosuarus are found in both South America and Africa.