INTRODUCTION 



So long has this view lasted, that even as late as 1891 we 

 find Professor Henry Drummond saying : " Finally, the thing 

 about the geology of Africa that strikes one as especially 

 significant is, that throughout this vast area just opening up 

 to science there is nothing new — no unknown force at work ; 

 no rock strange to the petrographer ; no pause in denudation ; 

 no formation, texture, or structure to put the law of continuity 

 to confusion."^ 



No doubt it is true that in Equatorial Africa the study of 

 ethnography is attended with special difficulties, the flora of 

 vast areas is poor in species, the rocks are monotonous in 

 character, and the paleontological record is a blank. Never- 

 theless the old view has been abandoned. African exploration 

 is now not undertaken only for the sake of obtaining fresh 

 topographical details, of undergoing adventures with cannibals, 

 and of " potting " big game. Instead of these we look to it to 

 supply us with information on some of the doubtful chapters 

 in the geological history of Europe, to give us insight into 

 unknown or unfamiliar methods in the earth's great workshop, 

 and to exert an important influence on the development of 

 scientific principles. 



Moreover, when studied from the modern point of view, the 

 topographical details themselves acquire a fresh value. The 

 investigation of the East African lake system has been the 

 branch of exploration in which the widest general interest has 

 been taken, ever since the native reports of the existence of the 

 great inland seas were verified by Burton and Speke's discovery 

 of Tanganyika (1857) and Livingstone's discovery of Nyasa 



(1859). 



Probably the most interesting series of journeys in the 



records of African travel were those made to the lakes of the 



great eastern plateau, including as it does the many efforts 



to settle the long controversy as to the position of Tanganyika 



in the African river system : Speke's two journeys to the 



Nyanza ; the circumnavigation of this lake by which Stanley 



proved its unity ; Baker's visit to the Albert Nyanza ; the 



expeditions in which Fischer discovered Lakes Natron and 



Naivasha, and Thomson demonstrated the isolation of Baringo ; 



Teleki and von Hohnel's exploration of Basso Narok and 



1 H. Drummond, Tropical Africa, 4th edition (1891), p. 199. 



