8o THE TANGANYIKA PROBLEM. 



into the African- Arabian land-mass now. It was, conse- 

 quently, one of our primary objects to explore the region 

 north of Tanganyika, as far as the Albert Nyanza itself, 

 and in the present chapter I shall therefore give an account 

 of these districts, as complete as the observations which we 

 collected will permit. I have intentionally treated this 

 part of the subject in a somewhat different manner from 

 the districts to the south, partly because it has hitherto 

 been almost unknown, and partly because the appreciation 

 of the structure, and the recent geological history of these 

 regions, is of the very utmost importance in attempting to 

 form any broad conception of the geographical features 

 which the greater part of Equatorial Africa now presents. 



What can be shown to have occurred between Tan- 

 ganyika and the Ruwenzori Mountains, probably within 

 the last ten thousand years, has completely changed the 

 relationship of the lakes and rivers, the watersheds and 

 drainage areas, throughout the whole of tropical Africa, 

 from the centre even to the very sea. 



In order to understand this country it is necessary to 

 start from some point to the south of the northern limit of 

 Tanganyika like Ujiji, from whence on passing northward 

 for about 70 miles, we find that the east coast of the lake 

 is, in reality, formed by a series of gigantic scarps, one 

 behind another. The first sweeps up precipitously from 

 the lake shore, but on journeying inland others are found 

 enclosing deep valleys, until, about 20 miles from the lake, 

 I reached a kind of plateau formed by the crests of these 

 ridges, which stood at heights varying from 7,000 to 10,000 

 feet. In general the crests were composed of sandstone, 

 conglomerates and quartzites, similar to those at the south 

 of Tanganyika, and these crests were broken away into 

 more or less well-formed cliff faces which looked towards 



