_ Large plateau in the north center of the on theSahara Desert Tropic of Cancer, north Africa. Its height is above 3,000 feet , culminating in Mount Tahatin southeastern Algeria. The plateau, about 965 miles north to south and 1,300 mileseast to west, is rocky desert composed of black volcanic necks and of flows rising above a pink granite massif. The main caravan route to Kano in northern Nigeria passes along the plateau’s western margin through the important oasis town of Tamanrasset, Alg., which is about 1,200 miles (1,900 km) south ofAlgiers. Natural-gas deposits have been found northwest of the plateau.