CONTRIBUTIONS TO THE GEOLOGY OF BENGUELLA. 



527 



they may be younger than the schistose quartzites that are found to the north of 

 them. It is, however, possible that they belong to the same division as the schistose 

 quartzite and gneiss, and represent granular quartzites due to the alteration of pure 

 siliceous sandstones. These Huambo quartzites appear to agree with the Kafubu 

 quartzites of South-Eastern Katanga and also with the Nzilo beds of North-Western 

 Katanga. The Nzilo beds are described by Studt (1914, p. 53) as compact to glassy 

 white and red quartzites which are granular and often show false bedding. This 

 description would apply well to the Huambo Quartzites, and Studt has suggested 

 that the Kafubu beds are of Cambrian age ; but I should incline, from their crystalline 

 character, to the view that the Huambo Quartzites are pre-Cambrian and belong to 

 the lower division of the Eozoic. 



(5) Bailundo Schistose Quartzites. — To the north and north-east of the Huambo 

 Quartzites are large outcrops of a schistose quartzite. These rocks are coarsely 

 foliated. They are traversed by planes of authigenous micas and pass by increase in 

 the new felspar into coarse gneisses. They are also interstratified with cordierite 

 and sillimanite schists. The schistose quartzites of the Ambussa Hills to the south 

 of Bailundo are typical examples of this group, which occupies a wide extent of 

 country to the north and north-east of Bailundo. The rocks have a very high dip, 

 are interstratified with the coarse gneisses, and belong to the highly crystalline 

 foliated Eozoic foundation. 



Weathered hand specimens of the older quartzites may be indistinguishable from 

 the quartzites of the Oendolongo Series ; but fresh material from the two series is 

 very different in character, and the quartzites which are interstratified with the 

 gneisses can be readily separated in the field by their higher dip. 



A limestone is reported to occur near Bailundo, but I was unable to visit the 

 locality. It is probably a crystalline limestone belonging to the Eozoic Series. 



Correlation of the Older Sediments. 



The suggested classification and relation of these rocks may therefore be sum- 

 marised as follows : — 





Equivalents in 



Geological Age. 



Congo. 



South Africa. 



Bihe Sandstones 



Oendolongo Series 

 Lepi Graywacke Series 



Huambo (Quartzites 

 Bailundo Schistose Quartzites 



Lubilash beds 



Kundelungu beds 

 Lubudi beds 



Nzilo beds and 

 Kafubu Quartzites 



Lower Karroo 



Waterberg System 

 Transvaal System 



I Swazi System 



Trias 



„ . (or perhaps 



Devonian J TT 



Lower Palaeozoic ) ™ • 

 { Eozoic 



Lower Eozoic 



TRANS. ROY. SOC. ED1N., VOL. LI, PART 111 (NO. 13). 



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