Appendix C. 



I1._RUWENZ0RI RANGE. 



Liflwlof/ical Cmdihilion. — The lliiweiizori Range, as already pointed out by 

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

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

 it is found to be essentially constituted of various gneisses and mira-scJiists in 

 which must have Ijeen originally enii)edded the (ireenslones which, after l)eing 

 exposed by the phenomena of denudation, to which they offered the greatest 

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

 valley of the Mobuku, we meet with a regular succession of rocks, in which 

 first occur the i/neisses whose correspondeueo witli the analogous rocks of 

 Uganda is olsvious. 



Amongst these gneisses the dominant variety appears to be the hiufi/e and 

 microdine of the Fort Portal district. With it are associated iinraeeous- 

 niiiphiJiiiJitirs and amphibolitic varieties in which the amphiholc is represented 

 1)V Iwnihknile. In the amphil)olic gneisses, however, the microcline is rare or 

 absent, being displaced, besides orthoclase, liy an aliundance of pla</ioclase 

 referable to andesife. 



The kafadusfic structure still continues together with frequent metallic 

 ores, such as hematite, magnetite, ilmenite, and chroniite, some varieties being 

 rich in tnnriiudine and giimet. 



The gneisses range up to about 11,600 feet in association with inica-sddsts, 

 the first type, however, being always dominant. Qmirtdtes also abound both 

 in thick beds and niidules. 



Above 11,600 feet the gneisses disappear, the iima-sdtists alone persisting, 

 associated with quart.:ites, and following without break up to the zone of the 

 greenstones. 



The rnica-schists of the Mobuku Valley are of two kinds, which constantly 

 recur : /iiinutc and foliaceous (lamellar). 



The first are formed of minute muscmile lamina', with abundant quartz, and 

 ne.xt to it felspar, mostly andesite ; in these the schistosity is not always evident, 

 while their compactness and hai'dness are very great. 



In the foliaceous kind niuscoiite prevails in large white silvery laniina>, 

 with which is associated a little minute hiotitr, while qnaii: and felsjuir l)ecome 

 rare. 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 



