166 A NATURALIST IN MID-AFRICA. 



The geology of Buwenzori is most curiously 

 different. Captain Stairs, who ascended the 

 mountain to between 10,000 and 11,000 feet, 

 believed that it was an old volcano, of which a 

 further account is given by Mr. Stanley (" In. 

 Darkest Africa," 1890, vol. ii. p. 257). 



Dr. Stuhlmann in his book " Mit Emin Pascha," 

 p. 298, points out that this theory is not borne out 

 by facts. He gives as his explanation that it is 

 a " faltungs-gebirge," situated between two lines 

 of dislocation. 



I found, however, that in my ascent by the 

 Nyamwamba valley, the most central rock which 

 I could reach was not, as one would suppose, 

 according to Dr. Stuhlmann's theory, a diorite, 

 but a rock which Dr. Gregory describes as either 

 a granite or a granitoid gneiss, and he suggests 

 that it is either an intrusive gneiss or a part of the 

 old Archaean or Victoria region series faulted up. 

 In this case Ruwenzori would be simply an oro- 

 graphic block or " scholl." The figure is intended 

 to show how the central block could have been 

 forced up. 



The mountain sides until this central core is 

 reached consist of a series of mica schists and 

 epidiorites. The former greatly perplexed me 

 on account of the manner in which the strike 

 seemed perpetually to vary, but I found on com- 

 parison afterwards that my observations of the 

 strikes all seemed to fit in with the theory that 



