SUMMARY 



OF THE GEOLOGICAL OBSERVATIONS MADE IN 

 UGANDA AND IN THE RUWENZORI RANGE 

 DURING THE EXPEDITION OF H.R.H. THE 

 DUKE OF THE ABRUZZI, 



BY 



ALESSANDRO EOCCATI. 



I.— UGANDA. 



Overlooking for the present the recent surface formations of concretionary 

 limonite and of hiterite, that part of Uganda which was traversed by H.R.H. 

 the Duke of the Abruzzi's Expedition was found to he for the most part 

 constituted of the crystalline rocks which foi'm the arch;ean plateau of Central 

 Africa. A not inconsideraljle tract, however, of the region traversed is covered 

 with sedimentary formations referable to the Palaeozoic Age, and in the inter- 

 mediate neighbourhood of Fort Portal there is an apparently limited zone in 

 which the crystalline rocks are overlaid by recent volcanic formations, 

 represented by stratified tuffs which I take to l:)e of subaqueous origin. 



ArrJuean. — On leaving Entebbe in the direction of the west, archiean 

 •crystalline rocks are followed from the shores of Lake Victoria nearly to 

 Mitiana. Here begin to appear the pal*ozoic formations, which, interrupted 

 here and there by out-cropping coarse-grained granite and pegmatite, extend to 

 ■within a few miles of Kasiba, where they suddenly disappear altogether, their 

 place being taken by the crystalline rocks, which continue westwards without 

 further Ijreak and thus constitute the whole of the Euwenzori Range. 



The archsean rocks are represented by mica-schists, gneiss, and granites (always 

 associated with numerous rjuartzites), amongst which are here and there noticed 

 intrusive greenstones, and seams of iiegmatite, microgmnite, etc. 



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