The result of tectonic processes is a broad, steep-walled trough extending from the Zambezi Valley in southern Africa northward to the Red Sea and the Jordan River valley in southwestern Asia.
The Great Rift Valley runs for nearly 5000km down the eastern edge of Africa from Syria to Mozambique. Varying in depth from a few hundred meters to almost 3000m in Kenya’s Mau Escarpment, it includes many well-known landmarks, from the Dead Sea to Lake Tanganyika.
The valley is the result of the gradual separation of the African and Arabian tectonic plates. The process at work is likely like the opening of the Atlantic about 200 million years ago. But it is not such a simple structure as the Mid-Atlantic Ridge.
In East Africa, the comparatively simple boundary at which two plates, the Nubian and Somalian, are splitting apart. But where the Rift meets the Red Sea, these two plates come up against the Arabian plate, making a triple junction. In time, the three plates could separate and leave present-day East Africa as the island, much as the Red Sea opening has split Saudi Arabia from Africa. In the meantime, volcanoes, hot springs, and other Earth symptoms beneath are rife along the Rift.