Appendix C. 



n._EUWENZORI RANGE. 



Lifholoffical Constitution. — The Ruweiizori Range, as already pointed out by 

 Scott Elliot, is regarded as a part of the archsean formation of Equatorial 

 Africa Avhich has been upheaved through phenomena of dislocation. In fact, 

 it is found to be essentially constituted of various f/neisses and mira-sciiisfs in 

 wliich nuist have been originally embedded the (jrcenxlones which, after being 

 exposed 1)y the phenomena of deinidation, to which they offered the gi'eatest 

 resistance, now form the loftiest crests of the whole range. Ascending the 

 valley of the Mol)uku, we meet with a regular succession of rocks, in which 

 first occur the gneisses whose correspondence with the analogous rocks of 

 Uganda is obvious. 



Amongst these gneisses the dominant variety appears to be the hiofifc and 

 microcline of the Fort Portal district. With it are associated micaceous- 

 ainphihoiifics and amphibolitic varieties in which the (iinpinholr is represented 

 bv hornìiìeniìc. In the amphil)olic gneisses, however, the microcline is rare or 

 absent, l>eing displaced, besides ortiiochm', l)v an al)undance of piivjioclase 

 referable to andesite. 



The kataclastic structure still continues together with frequent metallic 

 oi-es, such as hematite, magnetite, ilmenite, and chromite, some varieties being 

 rich in faiinuaìiiw and (jiirnet. 



The gneisses range up to about 11,600 feet in association with mica-schists, 

 the first type, however, lieitig always dominant. Quartzites also abound both 

 in tliick beds anil iioduk'S. 



Above 11,600 feet the gneisses disappear, the mira-schists alone persisting, 

 associated with iinaii-.Hrx, and following without break up to the zone of the 

 greenstcmes. 



The mica-schists of the Mobuku A'allev are of two kinds, which constantly 

 recur : rninutr and foliaceous {lamellar). 



The first are formed of minute muscovite lamina', with abmuhint quartz, and 

 next to it p'l.<iiai, mostly (imti'dtc ; in these the schistosity is not always evident, 

 while their ccjmpactness and hardness are very great. 



In the foliaceous kind musroritc prevails in large white silveiy lamina', 

 with which is associated a little miiuUe iiiotifr, while (/iiuii: and frlspar become 

 raie. In this second variety the schistosity and the cleavage are clearly seen. 



The two mica-schist types form beds of varying thickness, either standing 

 quite apart or else passing gradually into one another. They are always and 



388 



