THE TANGANYIKA PROBLEM. 
75 
extending the Tanganyika valley north and south. In 
the southern portions of Tanganyika there are no deposits 
of any kind besides the modern lake pleistocenes and the 
massive old African sandstones, while at the extreme 
north there are beds which extend to about twenty miles 
towards Kivu, and which in age appear to be intermediate 
between the Drummond series and the pleistocenes.* 
* In this connection may be mentioned what, if the marine animals in Tanganyika 
are a pre-cretaceous stock, has appeared to some geologists an unaccountable fact — 
namely, that on the west coast of the continent, to the south of the Cameroon moun- 
tains, for example, only cretaceous and post-cretaceous marine deposits have been found. 
This matter is now, however, in the light of our present fuller information readily 
intelligible. For we have seen that there were deposited in the interior, right across 
the valley of Tanganyika, in fact, aqueous beds, thousands of feet thick, which them- 
selves underlie the triassic series to the south ; and that subsequently the country was 
raised along the axis of the Great Central Range ; in consequence of which, the deposits 
in the interior are the oldest, and those nearer the sea, in general, progressively 
younger, as we proceed towards the coast. 
