Ecology and demography

Underlying the social and cultural complexity of East Africa is the complexity of the physical environment. ¹ East Africa enjoys a considerable variety of climate, terrain and vegetation. Basically, the greater part of the area is a vast, crystalline plateau, rising from a narrow coastal belt to a general altitude of between 3,000 and 6,000 feet above sea-level. This plateau is cleft by an immense series of valleys, known collectively as the Great Rift Valley, a gigantic crack appearing in the surface of the earth at the time of its formation. Within and between the Rift lie the great lakes of East Africa, the largest of them being Lakes Victoria, Tanganyika, Malawi (Nyasa), Rudolf, Albert, Kyoga, George, Edward and Rukwa. The depth of the lakes varies considerably. Tanganyika and Malawi are extremely deep, while Victoria is relatively shallow, and Lake Rukwa is subject to so much evaporation that it has been known to disappear entirely. Two of the great rivers of Africa rise from the East African Lakes, the Nile which takes its origin from Lakes Victoria and Albert, and the Congo which is partially fed by Lake Tanganyika and Lake Mweru. For the rest, there are relatively few rivers, the Rufiji and Pangani in Tanzania and the Tana in Kenya being the most important.