Vol. 51.] THE GEOLOGY OF MOUNT RUWENZORI. 669 



44. The Geology of Mount Ruwenzori and some Adjoining 

 Eegions of Equatorial Africa. By G. F. Scott Elliot, Esq., 

 M.A., B.Sc, E.L.S., and J. W. Gregory, D.Sc, F.G.S. (Read 

 June 5th, 1895.) 



Contents. 



Page 



I. Introduction 6(59 



II. Sections across and Structure of Ruwenzori 670 



(1) The Kivata Section. 



(2) The Yeria Section. 



(3) The Nyamwamba and Butagu Sections. 



(4) Volcanic Rocks on the Plains around Ruwenzori. 



(5) Conclusions as to the Structure of Ruwenzori. 



III. The Grlaciation of Ruwenzori 675 



IV. The Geology of the Country around Ruwenzori 676 



(1) The Archasan Series. 



(2) The Sedimentary Rocks. 



Map 671 



I. Introduction. 



Ruwenzori is a mountain-ridge on the right bank of the Semliki 

 branch of the Nile, between the two lakes Mwutan and Lutan Nzige 

 (the Albert and Albert Edward JNyanzas). It ranks as the third 

 snow-capped mountain in Africa, both in height and date of dis- 

 covery. Kilimanjaro was first seen in 1848 and Kenya in 1849, 

 and Ruwenzori only narrowly escaped detection a few years later. 

 Speke and Grant passed near it in 1862, but its existence was not 

 reported to them, though the natives whom they met must have 

 known of it. Sir Samuel Baker, in 1864, approached it from the 

 north, and reached a locality from which the mountain ought to 

 have been visible ; but he did not see the snow, and though his 

 ' Blue Mountain ' seems to have been Ruwenzori, he covered the 

 whole site of the mountain with a lake. Gessi Pasha circum- 

 navigated the Albert Nyanza in 1876 and went nearer to the 

 mountain than the point from which it was subsequently discovered ; 

 but he also missed it. Mason Bey, in 1877, followed the same 

 course, and though he stayed for some time for astronomical pur- 

 poses within sight of Ruwenzori, he never saw it. It was reserved 

 for Mr. Stanley, in 1888, to recognize that the white patches that 

 appeared among the clouds for brief and at distant intervals were a 

 snow-capped ridge. 



The late Capt. W. G. Stairs made an effort to ascend the moun- 

 tain in 1889, and reached a level determined by aneroid barometer 

 as 10,677 feet. All the high mountains of Equatorial Africa 

 known at this time were volcanic, and this consideration no doubt 

 helped Capt. Stairs to the belief that Ruwenzori also was an 

 old volcano. In his report to Mr. Stanley he thus expresses his 



