VI 
THE TANGANYIKA TROBLEM. 
upon the borders of such unknown lands. In the present case, all 
our results with respect to the fauna and topography of Xvassa, and 
much of the efficiency of the expedition further north, was due to 
the efforts of H.M. Commissioner, Mr. Alfred Sharpe, who allowed 
me to examine the lake from the gunboats, and facilitated our 
journey in many ways as far as the northern boundary of the 
British Central African Protectorate. In this way we were able 
to ascertain the actual depth of Lake Nyassa— 430 fathoms — a 
result which is sufficiently surprising, and one which, I am happy 
to say, has since been closely confirmed in an adjacent area by 
Commander Rhoades. In like manner we received much help in 
the selection of men and kindness generally from General Creagh, 
the British Resident at Aden ; from Mr. Codrington in Northern 
Rhodesia ; and perhaps I might also say we have been particularly 
indebted to Captain Bethe, and his brother officers in command of 
the German territory north and east of Tanganyika. In the later 
stages of the journey a great quantity of animals in spirit, and 
what remained of things in general, were hurried safely through 
Uganda to the coast by the help of H.M. Commissioner Mr. 
Jackson and Mr. Pordage at Mtebi. 
Turning from these details of the route to the subject of the 
investigations themselves, I should say at once that all the geo- 
graphical work, which has resulted in the first effective mapping of 
the region that had so long remained in dispute between Tan- 
ganyika and the Albert Nyanza, has been due to the energy and 
skill of my colleague Mr. I'ergusson, and in like manner much of 
the geological data with which I have had to deal in the sequel 
was originally collected and arranged by him. 
The revision of the existing geological conceptions of the 
African interior, which the information obtained during the Tan- 
ganyika Expeditions necessitates, will possibly be found the most 
generally interesting result that these investigations have pro- 
duced. It will be seen in the succeeding chapters that the whole 
of our current views of the geological nature of the Continent are 
radically unsound and incorrect. It can indeed be shown that 
even Suess’ conception of the graben (rift valleys) by no means 
always expresses the actual structure of these remarkable 
depressions, they are far better described under the title of 
