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 north, 
actually dip 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 
