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 
