THE TANGANYIKA PROBLEM. 89 



Chapter VII., totally different from that of Tanganyika. 

 It is, in fact, the fauna of a great fresh-water pond, and in 

 the plains which run southward under the modern volcanic 

 debris of the Mfumbiro Mountains, and to the ruprth, 

 actually clip under the water of the Albert Edward 

 Nyanza, there were encountered river-cuttings, in which 

 were exposed old lake-beds, underlying the superficial 

 drift and gravel of the valley's floor. In these beds 

 we found fossil-shells, all of which are identical with 

 those now found living in Lake Kivu, and embedded 

 in the magnesium incrustations of its shore. Further 

 north, the Albert Edward was found to contain the same 

 fresh-water shells alive which inhabit Kivu, and are found 

 fossilised in the beds extending under the more modern 

 volcanic dam between the lakes. 



There is now no connection whatever between Lake 

 Kivu, which stands at an altitude of 4,841 feet to the 

 south of the Mfumbiro Mountains, and the Albert Edward 

 Nyanza, which lies 2,000 feet lower, away to the north 

 of them, the watershed, formed by the modern volcanic 

 cones, rising everywhere to something over 7,000 feet, 

 between the lakes ; but we have in the above facts in- 

 contestable evidence that the waters of Lake Kivu and 

 those of Lake Albert Edward Nyanza were, at some no 

 very remote time, in connection. The formation of the 

 modern volcanic dam has simply resulted in the banking 

 up of the water of Lake Kivu, until it finally flowed to the 

 south over the high gneissic ridges, which originally sepa- 

 rated the Kivu and Tanganyika valleys. The effect of this 

 change in the position of the central watersheds of the 

 African continent has unquestionably had an immense 

 effect, both in the regions far to the north and far to the 

 south of it. By the formation of the volcanic dam, the 



