A])pcn(lix C. 



although some specimens present a typical graphic association of quartz with 

 microcliiie. 



In the Lwamutukuza, jMuyongo and Fort Portal districts I noticed in the 

 gneiss-granitic formation consideralilo intrusions of diabase rocks of granular and 

 sometimes coarse-grained structure. The specimens collected by us never 

 contain olivine, nor even the chloritic green pigment so common in the rocks 

 of this type in our lands ; characteristic is always the abundance of ilmenite, as 

 also the basic felspar often referalile to miorlliitc. 



Thanks to the metamorphosis of the pyroxenes in amphiboles, which may 

 be easily followed in its various transitions, some of these diabases pass over to 

 ('liidioiite ; true dimite I did not come across in situ, but believe that it occurs in 

 the Kaibo-Butiti district. Conspicuous also, between Fort Portal and Duwona, 

 is a thick bed of overlying hypersthene gahhro of coarse structure. 



Falwor.oic- — The formations which represent the Palreozoic Age follow for 

 about 50 miles between Mitiana and Kasiba. Their eastern limit did not appear to 

 be very clearly marked, whereas the western is distinctly defined by the granitic 

 range which I have described as extending from Kasiba to jNIuyongo. It is in 

 fact against these very escarpments that the palajozoic formations are inclined. 



The rocks met in the district are sandstones, arkoses, quaridtes, quartzite 

 breccias and various schists, micaceous or talco-miaiceous. All these rocks, whose 

 clastic and metamorphic origin is readily recognized in the jjetrographic 

 laljoratory, are for the most part coloured a deep red, and correspond perfectly 

 to the rocks referred to the Palaeozoic Age, as described by observers in other 

 parts of Uganda, as well as in Congoland and South Africa. 



An exact determination of age is too often prevented liy a total lack of 

 fossils. I think, however, that it may be useful to point out how some of the 

 schists met by me greatly resemble analogous formations of the Permian 

 Epoch in the Alps, and how, as we proceed westwards, the series seem dis- 

 tinctly to pass from the sandstones to the schists, thus suggesting a steady 

 increase of metamorphism in that direction. 



liccent fiiniHiiions. — These are represented by the cona-etionari/ liinonite (the 

 ironstone of English writers), and liy lati'iite. 



The concretionary limonite is one of the characteristic formations of the 

 Lake Victoria region. 



Already on the east shore, and then in a typical manner on the west, in 

 the Entebbe district and beyond it, we may say as far as the Kasiba-Muyongo 

 granitic zone, the ground is covered with a concretionary limestone, at times 

 pisolitic (pea-like) or vacuolated, always very compact, colour shifting from a 

 bright red to a brownish-yellow or dark brown. 



384 



