GEOLOGY. 171 



mica schists, amongst which were intrusive bands 

 or dykes of lava. 



Then an elliptic area (now the central core) was 

 elevated relatively to the surrounding region. The 

 mica schists were carried up with it, and now 

 slope away from the ellipse, and their included 

 bands and dykes have become greatly altered 

 epidiorites (see Fig. 26b). 



This elevated mountain mass, surrounded by the 

 depressions of the Semliki valley, Albert Edward, 

 the Ruisamba, could not have been formed without 

 the production of lines of weakness or dislocation. 

 The recent volcanic cones probably appeared 

 afterwards along these lines. Thus of the four 

 groups mentioned above, the Yijongo chain is 

 almost north-east ; Butanuka is nearly due east ; 

 while the Salt lake area (which may have formed 

 the curious narrowing of the entrance of Ruisamba 

 at Kaihura) lies roughly south-east, that at Karimi 

 being approximately south-west. I should be very 

 much interested to know if there are any similar 

 lines of weakness to the north-west of Ruwenzori, 

 but I cannot find evidence of this. 



The appearance of the soil, not to speak of the 

 lakes, is very different to anything seen elsewhere. 

 It has a curious resemblance to the blue earth of 

 Kimberley, but I regret to say that I did not find 

 any trace of diamonds ! In fact, I have never seen 

 any valuable minerals excepting iron in the British 

 East African sphere, and I am disposed to ques- 

 tion their existence. 



