Gregory Rift

The Gregory Rift is the eastern branch of the East African Rift system, formed as the Somali Plate separates from the Nubian Plate, and it is sometimes narrowly defined as just the Kenyan Rift even though the broader feature extends from the Gulf of Aden through Ethiopia and Kenya into northern Tanzania. Its shoulders rise more than 3,000 meters above sea level, about 1,000 meters above the inner graben floor, and the rift is widest in the northern Afar region before narrowing to only a few kilometers in northern Tanzania, where it splays into the North Tanzania Divergence. The Tanzanian stretch of the rift holds Mount Kilimanjaro, Africa's highest mountain, the Ngorongoro caldera, and Ol Doinyo Lengai, the world's only active carbonatite volcano, and the rift's ancient lake sediments, including beds up to 4 kilometers thick beneath Lake Turkana, have yielded important hominin fossils.