The theory of plate tectonics explains the history of the earth's surface. It is believed that the modern continents were once all part of one super-continent called Pangaea. Scientists theorize that Pangaea first broke into two continents and eventually split further into the continents that exist today. Look at Figure 5.2.1 above; do you see how the east coast of South America matches up with the west coast of Africa? Scientists point to the matching-up of the coasts along the continents as evidence that the theory of plate tectonics is accurate. Figure 5.2.1 shows how the continents may have fit together before drifting apart. In addition to fitting the coastlines together, scientists have found that rock formations also match up along the edges of the continents. For example, the rock formations along the east coast of South America match the rock formations along the west coast of Africa. The matching rock formations provide more evidence supporting the theory.