Great Rift Valley, a geological fault system stretching about 4,000 miles (6,400 km) from the valley of the Jordan River in southwestern Asia to the Zambezi River in Mozambique. It is the longest fault system in the world. Elevations range from about 1,300 feet (400 m) below sea level in the Dead Sea to more than 6,000 feet (1,800 m) above sea level in southern Kenya.

South of Ethiopia the Great Rift Valley divides into an eastern and a western branch. The eastern branch, which runs through Kenya and Tanzania, has many volcanoes and several shallow lakes. At some points the valley is marked by steep-sided cliffs. The western branch, which runs along the Democratic Republic of the Congo's eastern frontier, is marked by a chain of large, deep lakes and has few volcanoes. The branches converge at Lake Nyasa, in southeastern Africa, and continue south as one system to central Mozambique.