33§ 
THE TANGANYIKA PROBLEM. 
the sea ; but even if there were such evidence, unless it 
was of the most positive and trenchant kind, not mere 
negative appearances, I should regard it as being quite 
worthless in the face of the positive zoological facts of 
the case. 
It would seem in fact that it is inherently impossible 
to arrive at any positive geological evidence which would 
actually veto the possibility of the sea having reached Tan- 
ganyika. For example, suppose it could be shown definitely 
that there were no marine deposits in a certain county in 
England, is that fact in itself proof positive that it has 
never been below the sea ? The problem is not one which, 
it appears, can be solved along geological lines ; but the 
facts of zoology are before us, and are plain enough to any- 
one who likes to take the trouble to understand them ; and 
if the negative geological appearances of Central Africa 
remain and in reality cannot be brought into accord with 
them, this simply shows the impotence of the geological, 
as compared with the zoological, methods of research. 
Zoological evidence having, in fact, to be brought forward 
to indicate to geology the gross outline of the past history 
of Africa, and the way out of the theoretical entanglements 
in which it is at present wrapped up. 
