The Rift Valley of East Africa is the southern end of a 4000 mile rift that begins in the Beqaa Valley of Lebanon and extends southward through the Jordan River Valley, the Dead Sea, the Gulf of Aqaba and the Red Sea. At the southern tip of the Red Sea, an eastern branch runs through the Gulf of Aden, extending to the mid-oceanic ridge of the Indian Ocean.
The African portion of this Great Rift, which began to develop 40 million years ago, is comprised of two parallel rift valleys which stretch from Ethiopia to Mozambique. The western channel harbors some of the larger lakes in Africa, including Lake Tanganyika, one of the deepest freshwater lakes in the world. The eastern rift is well known for its early hominid fossils (especially within the Olduvai Gorge) and is characterized by a chain of basin lakes; with no outlet to the sea, these shallow lakes flucutate throughout the year, leaving broad salt flats during the dry season.
As is true with other rift areas, volcanic features are common throughout the Rift Valley; the rifting process is often triggered by the development of mantle plumes and, as the crust is stretched and thinned, lava flows and volcanoes develop. Volcanic mountain chains rise along both channels of the African Rift but the most famous, Mt. Kenya and Mt. Kilimanjaro, developed along the eastern rift. The Ngorongoro Crater, known for its fabulous diversity of wildlife, is the remnant of a large volcano in the eastern rift of northern Tanzania; fourteen miles wide, it is one of the largest intact volcanic craters on Earth.
Over time, the Rift Valley of Africa will be invaded by the sea, just as happened in the Red Sea, the Gulf of Aden, the Gulf of California and numerous other rift zones across the globe; once this happens, the sub-Continent of East Africa will break from the motherland.
