vi THE TANGANYIKA PROBLEM. 



upon the borders of such unknown lands. In the present case, all 

 our results with respect to the fauna and topography of Nyassa, 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. Fergusson, 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 



