My website came from: http://geology.com/articles/east-africa-rift.shtml

In East Africa there is an area where Earth’s tectonic forces are currently trying to create new plates by splitting apart old ones. This rift area is defined by a fracture in the earth’s surface that widens over time and thus becomes a new plate. The two main plates at play are the Nubian Plate, which makes up most of Africa and the Somalian Plate, which is the plate pulling away. Contained within the area of these splitting plates includes Kenya, Ethiopia, and Somalia.

There is an ongoing debate among scientists about how the rift has formed. The most popular model assumes that the elevated heat flow coming from the earth’s mantle is causing a pair of thermal bulges in central Kenya and areas north of Kenya. This heating process causes heats up the overlaying crust causing it to expand and fracture. The expansion further stretches the land and leads to the formation of oceanic crust, which creates the birth of a new ocean basin.

This area is represents a unique geological setting that may also provide some insight into the process of human evolution. Many early hominid fossils have been found within and around the East African Rift System. Since the structure and evolution of the rift may have created climate changes, early hominids would have needed to adapt to such changes. The alterations in climate structure may have driven humans to become bipedal and more brainy as they tried to adapt the changing environment.