Ol doinyo Lengai, the Maasai's Mountain of God, in early morning sunlight. It is the only active volcano in the Gregory Rift - an important section of the eastern branch of Africa's Great Rift Valley. This 9,400-foot-high volcano with deeply eroded sides stands 7,000 feet above the surrounding plains. It still discharges rare carbonatite lavas, which turn white on exposure to air.The last major eruption took place in 1966 although small-scale eruptions within the summit have occurred regularly since 1983.