68 PRESIDENTIAL ADDRESS SECTION B. 



and several areas of older granite and Karroo rocks in the South- 

 western Transvaal. 



Including as it does the greatest gold-field and the two 

 greatest alluvial diamond fields in the world, this is easily the 

 most important of the nine divisions, contributing about 80 per 

 cent, by value of the total mineral output of the Union. 



In addition to gold and diamonds, it yields silver, coal, 

 asbestos, building-stone, quartz, talc, and a considerable variety 

 of clays. 



As regards future discoveries, the possibility of locating 

 further outcrops of the Main Reef, or areas underlain by it, will 

 doubtless continue to act as a powerful incentive to prospecting 

 and boring within the tract of country over which the Witwaters- 

 rand beds are known to extend.* 



On the whole it does not appear likely that the productive 

 area of the Rand gold-field will be very materially added to, 

 either to towards the east, south-east, or west. It is possible, 

 however, that some of the work now being carried out in the 

 Heidelberg area may bear fruit, and that the faulted continuation 

 of the Main Reef zone will eventually be located beneath the 

 Dolomite to the south-west of the Randfontein group of mines. 

 There is also a remote possibility that a " Farther "' East Rand 

 may await discovery below the coal-measures of the Bethal and 

 Middelburg districts, but this systematic deep-boring alone can 

 decide. 



In regard to the Venterskroon and Klerksdorp gold-fields, 

 the outlook is not very hopeful. The prospecting and boring 

 operations carried out in the former area some years ago, under 

 the direction of Dr. Corstorphine, render it practically certain 

 that the Main Reef zone does not exist in the Witwatersrand 

 beds as developed within it. 



In so far as the Klerksdorp district is concerned, it still 

 remains to be proved whether or not the Main Reef zone is 

 represented, and, until the complex geological structure of the 

 area has been more completely unravelled, it will hardly be 

 possible to do this. Some geologists have identified Buffeldoorn 

 Reef, until recently worked by the Quest Gold Mining ( onipany, 

 with the Main Reef, but the correlation rests on rather a slender 

 basis. 



In any case, the disappointing results obtained from the 

 exploitation of this ' reef " indicate that, if it is the Main Reef, 

 the latter is verv th'n and patchy in the Klerksdorp district. 



Coal. — Fairly considerable quantities of coal are produced 

 from the coal-measures overlying the Witwatersrand beds and 



* The most easterly exposure of undoubted Main Reef zone hitherto 

 located is on, or more correctly speaking, beneath the farm Droogefontein- 

 No. 447, on the Far East Rand ; the most westerly, in the south-western 

 corner of the claim-holaing of the South Randfontein Deep, on the Wefet 

 Rand; and the most southerly, on the farm Platkopje, No. 63, 16 miles 

 south-west of Heidelberg. 



