Appendix C. 
II.—RUWENZORI RANGE. 
Lithological Constitution. —The Ruwenzori Range, as already pointed out by 
Scott Elliot, is regarded as a part of the archaean formation of Ecpiatorial 
Africa which has been upheaved through phenomena of dislocation. In fact, 
it is found to be essentially constituted of various gneisses and mica-scliists in 
which must have been originally embedded the greenstones which, after being 
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 gneisses whose correspondence with the analogous rocks of 
Uganda is obvious. 
Amongst these gneisses the dominant variety appears to be the hiotite and 
microcline of the Fort Portal district. With it are associated micaceous- 
amphibolitics and amphibolitic varieties in which the amphibole is represented 
by hornblende. In the amphibolic gneisses, however, the microcline is rare or 
absent, being displaced, besides mihodase, by an abundance of plagioclase 
referable to andesite. 
The kataclastic structure still continues together with frequent metallic 
ores, such as hematite, magnetite, ilmenite, and chromite, some varieties being 
rich in tourmaline and garnet. 
The gneisses range up to about 11,600 feet in association with mica-schists, 
the first type, however, being always dominant. Quartzites also abound both 
in thick beds and nodules. 
Above 11,600 feet the gneisses disappear, the mica-schists alone persisting, 
associated with quartzites, and following without break up to the zone of the 
greenstones. 
The mica-scliists of the Mobuku Valley are of two kinds, which constantly 
recur : minute and foliaceous (lamellar). 
The first are formed of minute muscovite lamina’, with abundant quartz, and 
next to it felspar, mostly andesite ; in these the schistosity is not always evident, 
while their compactness and hardness are very great. 
In the foliaceous kind muscovite prevails in large white silvery laminae, 
with which is associated a little minute hiotite, while quartz and felspar become 
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 
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