Note 119 — Chapter XXVIII · THE GEOGRAPHY OF THE NILE BASIN

This lake is at present one of the unsolved African problems as regards its history and affinities. Unlike other lakes of Central Africa, its fauna has marine affinities, and would seem indeed to be actually of marine origin. It is at the present day connected somewhat intermittently with the Congo drainage, and therefore with the Atlantic Ocean; and one assumption to explain the existence of its sponges, shrimps, and jelly-fishes is that in Jurassic times it was connected with a vast inlet of the Atlantic Ocean which occupied the northern half of the low-lying Congo basin. Yet, when a relief map of Africa is looked at, it strikes one at a glance that Tanganyika lies within the same rift valley as Lakes Kivu, Albert Edward, Albert Nyanza, and the Albertine Nile. Its southern end may also have been connected through Lake Rukwa, with the rift valley of Lake Nyasa. It would be easy to imagine the occurrence of a recent and slight upheaval which detached this lake from the Nile system and sent its overflowing waters in the direction of the Congo, but for the aforementioned marine fauna of its waters. Its history, therefore, remains at the present moment an unsolved problem.