C. B. Honvood Sf A. Wade— The Old Granites of Africa. 503 



In order to show the widespread areas covered by this gneiss 

 formation, he points ovit that Dantz ' maps the central and northern 

 parts of German East Africa as an enormous area of gneiss, in which 

 he distinguishes between the peripheral zones of gneiss of particularly 

 well-foliated character and the central part of granitic character ; and 

 that Tornau noticed gneisses of every variety in the TJluguru Mountains, 

 but that generally in other parts of the Colony through which he 

 travelled coarsely-grained granite prevails, showing throughout the 

 same uniform composition and character, without any signs of foliation, 

 and this he called typical granite, which is probably identical with our 

 Old, intrusive, Granite. 



Mr. Tornau states that the gneisses are older than the granite ; for 

 instance, he found, towards the south of the Nyassa, rounded gneiss 

 fragments of all varieties, with sharp contours, in the granite. 

 Dr. Voit" says he found a similar gneiss formatio7i in the interior 

 of Angola, which he jiut down as Fundamental Formation, consisting of 

 granite and coarse-grained gneisses, in which the granite was intrusive, 

 and that these gneisses showed a remarkable resemblance to the foliated 

 gneisses of the Limpopo. He further says that it appears that 

 certain gneisses south of the Gansberg in German South-West Africa 

 ought to be separated from the intrusive granites, and classed as an 

 independent formation. He says it is interesting to the geologist who 

 has seen more of Africa than the South to observe that the Swaziland 

 Series with intrusive granite seem to prevail in the South of Africa, 

 while proceeding towards Rhodesia and Central Africa the gneisses 

 with intrusive granites predominate.^ 



Dr. Voit^ also found the Old Granite intrusive in the gneisses of 

 the Engoye Mountains in Zuhxland ; and also correlates the gneiss 

 formation (in which the Old Grey Granite is intrusive) of the '2skandhla 

 district of Zululand with the granite-gneiss formation of the Limpopo. 

 The Swaziland Series also occurs in the 'Nkandhla bush. 



He concludes by stating that we therefore have two distinct 

 formations in which the Old Granite is intrusive — a coarse-grained, 

 highly- crystalline rock of well-foliated character, similar to the very 

 oldest gneiss of Laurentian age, and of undoubted igneous origin ; and 

 the Swaziland Series, of undoubtedly sedimentary origin, with igneous 

 sheets of diabasic rocks. 



In discussing Dr. Voit's first paper on this gneiss formation of the 

 Limpopo Flats, Mr. H. S. Harger* stated that he had been over this 

 ground in the Limpopo region and that he had also come across 

 a similar formation, consisting of hornblende-gneiss, garnet-gneiss, 



' Paper read by Mr. Toraau before the Deutsche Geologfsche Gesellschaft, Berlin, 

 March 6, 1907. 



2 " Prelimiuary Notes on ' Fundamental Gneiss Formation ' in South Africa," by 

 Dr. F. W. Voit (Trans. Geo). Soc. S.A., 1905, vol. viii, p. 107), and "Gneiss 

 Formation in Africa", by Dr. F. AV. Voit (Trans. Geol. Soc. S.A., 1907, 

 vol. X, p. 92). 



3 " Gneiss Formation in Africa," by F. W. Voit: Trans. Geol. Soc. S.A., 1907, 

 vol. X, p. 92. 



* Loc. cit., p. 93. 



5 Proceedings of the Geol. Soc. of South Africa (to accompany vol. viii of the 

 Transactions), 1906, pp. o7, 58. 



