Vol. 51.] ON THE GEOLOGY OE MOUNT RTTWENZORI. 679 



In the Ruampala Mountains the rocks of this series are associated 

 with a number of iron ores which occur in approximately the same 

 position as those of the Samia Hills. The ridges are crowned with 

 a granular quartzite, while the rock near the gneiss is a coarse 

 schistose sandstone. The actual junction-rock near Kiarutanga 

 [89*] is a laminated, micaceous sandstone, which appears to have 

 been to some extent flattened out by pressure. Elsewhere, as at 

 Tiasimbe, the rock in contact with the gneiss series is a red sand- 

 stone, so that the sedimentary series no doubt rests unconformably 

 on the Archaean rocks. 



The extent to which the rocks have been altered varies con- 

 siderably. In some cases the rocks are simple massive sandstones 

 (as at Tiasimbe) or altered shales (as at Ruetembe on the Kagera) ; 

 in others they have been crushed into schistose quartzites and 

 hard, siliceous slates with imperfect foliation (as in the Ruampala 

 Mountains), or into a well-cleaved clay-slate or killas (as at 

 Kitangule). 



The rocks around Ujiji are probably part of the same series. 

 They are coarse quartzose grits, red, iron-stained, and yellowish 

 sandstones. At Niamkorio, at the southern end of Tanganyika, a 

 white laminated sandstone appears to represent the same series. 



Discussion. 



The Chairman (Mr. W. H. Hudleston) congratulated the Society 

 on having received a geological paper from two distinguished 

 geographers, since he had always regarded geography and geology 

 as sister sciences. "We are told of the effects both of fire and frost 

 in this remarkable region. As regards the former, he owned to 

 a feeling of disappointment that Mount Fuiwenzori proves not to 

 be a volcano. It would seem to belong to a not uncommon type 

 of mountain, where a granite core is flanked by various schists, 

 though the Authors had suggested and possibly favoured another 

 alternative. 



Dr. Blaneord called attention to the fact that Ruwenzori was the 

 only instance known of a mountain in Africa south of the Tropic of 

 Cancer that exceeded 10,000 feet in height and was not composed 

 of volcanic rocks. He enquired about the lowest elevation at which 

 glacial markings occurred, and noticed that the discovery of these 

 markings on a second Central African peak was rather opposed to 

 Dr. Gregory's view that Kenya had been depressed. On the other 

 hand, no glacial markings appeared to have been observed on 

 Kilimanjaro, and the speaker had looked for them unsuccessfully in 

 Abyssinia at 10,000 feet above the sea. The evidence of biological 

 distribution was in favour of a general refrigeration of the earth's 

 surface in Pleistocene times. 



Sir Henry Howorth also spoke. 



Mr. Scott Elliot said that, with regard to the authorship of 

 this paper, his work had merely consisted in bringing back speci- 



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