<P> The African continental crust is generally cool and strong . Many cratons are found throughout the EAR, such as the Tanzania and Kaapvaal cratons . The cratons are thick, and have survived for billions of years with little tectonic activity . They are characterized by greenstone belts, tonalites, and other high - grade metamorphic lithologies . The cratons are of significant importance in terms of mineral resources, with major deposits of gold, antimony, iron, chromium and nickel . </P> <P> A large volume of continental flood basalts erupted during the Oligocene, with the majority of the volcanism coinciding with the opening of the Red Sea and the Gulf of Aden approximately 30 Ma . The composition of the volcanics are a continuum of ultra-alkaline to tholeiitic and felsic rocks . It has been suggested that the diversity of the compositions could be partially explained by different mantle source regions . The EAR also cuts through old sedimentary rocks deposited in ancient basins . </P> <P> The East African Rift Zone includes a number of active as well as dormant volcanoes, among them: Mount Kilimanjaro, Mount Kenya, Mount Longonot, Menengai Crater, Mount Karisimbi, Mount Nyiragongo, Mount Meru and Mount Elgon, as well as the Crater Highlands in Tanzania . Although most of these mountains lie outside of the rift valley, the EAR created them . </P> <P> Active volcanos include Erta Ale, DallaFilla, and Ol Doinyo Lengai, the former of which is a continuously active basaltic shield volcano in the Afar Region of northeastern Ethiopia . When DallaFilla erupted in 2008 it was the largest volcanic eruption in Ethiopia in recorded history . The Ol Doinyo Lengai volcano is currently the only active natrocarbonatite volcano in the world . The magma contains almost no silica, making the flow viscosity extremely low . "Its lava fountains crystallize in midair then shatter like glass" according to the National Geographic . Approximately 50 volcanic structures in Ethiopia alone have documented activity since the onset of the Holocene . </P>

The east african rift extends north and south between what latitudes