34 THE TANGANYIKA PROBLEM. 



ice-capped as it is. It is only comparatively recently that the 

 existence of these interior heights has become known, and 

 it is only quite recently that the conception of a long axial 

 rano-e in Africa, bearino- the same relation to that continent 

 that the Andes do to South America, has begun to be 

 appreciated. It is indeed to Mr. Scott Elliot* that we owe 

 the first clear apprehension of this fact, and it is such a very 

 important fact in all questions of African physiography, that 

 I shall attempt in this, as in a former work,f to emphasise 

 the appreciation of it by giving the mountain chains a 

 special name and by speaking of them as " The Great 

 Central African Range." 



The main river systems of Africa flow from the eastern 

 and the western slopes of this range, and the greater rivers, 

 partly owing to its position partly to climatic conditions 

 respecting rainfall, flow mainly from the western slopes. 

 The immense Congo, with all its gigantic upper tributaries, 

 rises wholly on the west, while even the Nile, with its main 

 components, the Albert Nile, the Sobat and the Blue Nile, 

 drains mainly from the western slopes. So also, even the 

 Zambesi derives most of its water from the west of the 

 range, although it eventually cuts through the chain to an 

 opening in the Indian Ocean. 



As is the case in the region of most great mountain 

 ranges, there are to be found in Central Africa besides 

 the chains of lofty heights, long, deep hollows which run 

 parallel with, and between the ridges of the range itself, 

 and these great depressions, which are now occupied 

 by the lakes and the rivers, are often rock valleys, 

 like the valley of Geneva. They have not, however, 

 been formed by ice, and are not to be viewed as wholly 

 the products of denudation operating in the past, any more 



* A Naturalist in Mid- Africa (1896). t To the Mountains of the Moon. 



