54 



CHAPTER IV. 



THE SUPERFICIAL GEOLOGY OF THE REGIONS OF THE 

 GREAT LAKES. 



In the preceding chapter it was seen that the whole of the 

 geology of a very large portion of Central Africa is sub- 

 ordinated to, and is in fact an expression of, the gradual 

 folding and elevation of the earth's surface in wrinkles 

 running parallel with the theoretical axis of the Great 

 Central Range. That there was a time in which no central 

 range existed goes without saying, and that there were also 

 many periods during which the characters of the interior 

 were not those of the present day, is made clearly evident, 

 as we have seen, by the simple fact that at some time 

 horizontal strata stretched across the present site of 

 greatest elevation and distortion, both in the region of 

 Lake Nyassa and Lake Tanganyika ; while, lastly, it 

 is made clear by the observations I have described relating 

 to the recent depression of the floor of Nyassa in the 

 north, and the elevation elsewhere of the bottom of the 

 lake, which has occurred as late and later than post- 

 pleistocene times, that the activity of the continent with 

 respect to the Great Central Range is not yet dead. There 

 has, moreover, evidently occurred a succession of efforts in 

 such movements, and these efforts are, in several places, 



