132 REPORTS ON THE STATE OV SCIENCE 



shown elsewhere J that, without making any allowance for the great 

 intervals between the Waterberg and the Potchefstroom (or Transvaal) 

 Systems, between the Potchefstroom and the Ventersdorp Systems, 

 between the Ventersdorp and the Witwatersrand Systems, and between 

 the Witwatersrand and the Swaziland Systems, there are, reckoning 

 from the base of the Waterberg and the top of the Swaziland Systems, 

 at least 45,000 feet of strata; while the thickness of the Swaziland 

 beds, which is, of course, very great, is unknown. 



The Swaziland System consists largely of crystalline schists with 

 intrusive granite-bathyliths, and this, taken together with the fact that 

 it lies below three big pre-Devonian Systems of strata, each separated 

 from the one above it by great discordances, makes it not unlikely 

 that this system represents the Archaean, or a portion of the Archaean, 

 of other countries. But since, after all, we only know with certainty 

 that it is pre-Devonian, it would be better for present purposes to 

 eliminate the use of the word Archaean from South African geology 

 altogether. The same reasoning applies to the suggested introduction 

 of such terms as Algonkian and Archeozoic. 



As to the Witwatersrand, the Ventersdorp, and the Potchefstroom 

 (or Transvaal) Systems, any attempt at correlation with the systems of 

 other countries is, in the absence of fossil evidence, out of the question. 



Coming now to nomenclature, the name Witwatersrand System 

 is now generally accepted. With regard to the Ventersdorp System, 

 this name was proposed by myself 2 for a formation, comprising boulder 

 beds, conglomerates, 3 volcanic breccias and lavas, and totalling at least 

 8,000 feet, which unconformably overlies the Witwatersrand System, 

 and is itself transgressively overlain by the Black Beef Series, or lowest 

 beds of the Dolomite Series. The name appears to me decidedly pre- 

 ferable to Vaal Biver System, since the latter is apt to lead to a confu- 

 sion between the topographical expression, 'Biver System,' and the 

 stratigraphical term. Ventersdorp System has, moreover, the priority. 



With regard to ' Potchefstroom System ' versus ' Transvaal System,' 

 the latter term is the older ; but since the use of the name of a country 

 for a system, which, after all, plays only a minor role in its geological 

 structure, seemed as objectionable as if the Devonian System of England 

 had been called the 'English System,' Dr. Corstorphine and myself 

 proposed that ' Transvaal System ' should be abandoned in favour of 

 'Potchefstroom System,' all three members of the system being de- 

 veloped in the district of that name, and the nomenclature being in 

 conformity with that used in the Witwatersrand, Ventersdorp, and 

 Waterberg Systems. 



The term ' Lydenburg System ' would have been eminently suitable 

 but for the fact that Dunn had previously used it to include not only 



1 Presidential Address to the Geological Society of South Africa for the year 1906. 

 Minutes of Proceedings, Geol. Soc. South Africa, 1906, vol. ix. 



2 F. H. Hatch : ' The Boulder Beds of Ventersdorp,' Trans. Geol. Soc. South 

 Africa, vol. vi. (1904), p. 95. ' Vaal River System ' was proposed by Molengraaff in the 

 English edition of The Geology of the Transvaal (1904), p. 19. 



8 Prof. Schwarz is incorrect in saying that this is a volcanic series only, for it 

 includes boulder beds, conglomerates, and sandstones of sedimentary origin (Elsburg 

 Series). 



