192 LAKE KIVU 



waters of Lake Kivu to their present extraordinary 

 height of 4,800 feet. 



It has been remarked above that the hills across 

 the floor of the great trough to the north of 

 Tanganyika formerly constituted the watershed 

 between these two lakes ; but as the waters of 

 Lake Kivu were prevented by the dam from flowing 

 into the Nile system, they rose higher and higher, 

 probably through many centuries, until finally they 

 overflowed the old watershed, and poured down 

 into Tanganyika by the new Rusisi River. The 

 remote effects of the volcanic outburst did not 

 stop there, for Tanganyika, swollen by the addition 

 of the Kivu water, rose until it was able to cut a 

 channel through its western wall, by which some 

 of its waters flow into the Congo. Thus it is 

 seen that, by the simple damming up of the great 

 Central African trough, two great lakes have been 

 added to the Congo system, while the Nile has 

 not only lost Lake Kivu, but the Albert and Albert 

 Edward Nyanzas have been greatly diminished in 

 size, and other lakes, which possibly lay between 

 them, have disappeared. 



It is practically certain that the formation of 

 the mountains started in the east and proceeded 

 towards the west, as it is only the two most western 

 volcanoes which exhibit signs of activity at present. 

 This latter fact tends to prove that the actual cutting 

 off of Lake Kivu from Lake Albert Edward took 

 place in quite recent times, as the western slopes 



