BULLETIN OF THE GEOLOGICAL SOCIETY OF AMERICA 

 Vol. 23, pp. 297-316, PLS. 12-14 JUNE 28, 1912 



PLATEAU OF BRITISH EAST AFRICA^ 



BY GEORGE LUCIUS COLLIE 



(Presented before the Society December SO, 1911) 



CONTENTS 



Page 



Introductory -•^'^ 



Physiographic provinces and their relation to geological structure 290 



The coastal plain 200 



The shoreline 200 



Structure and character 200 



The foot plateau — its character and structure 300 



The gneiss province , 302 



Character and structure 302 



"Valleys and divides 303 



Monadnocks 303 



The relief. 304 



The lava province 304 



Extent 304 



Character and structure 305 



Drainage systems and valleys 305 



Peneplanation of the plateau 307 



Character of surface and its elevation 307 



Climatic factor 307 



Other factors 308 



Method of peneplanation 309 



The Rift Valley 312 



Position and extent 312 



Origin 312 



Escarpments and platforms 313 



The valley floor 314 



Lakes and lake basins 315 



Drainage of the valley 315 



Fate of the Rift Valley 316 



Introductory 



The observations embodied in this paper were made along the route 

 of the Uganda Railway during the months of July and August, 1910. 



1 Manuscript received by the Secretary of the Society January 29, 1912. (297) 



