THE WITWATERSRAND GOLD REGION 743 
grade, one or both of the Leaders often being of much better grade 
than either the Main or South Reef. Though the conglomerates 
carry most of the gold, in fact all the gold that is mined in the Main 
Reef series, yet small quantities have been found in some of the quartz- 
ites. 
The gold-bearing rocks of the Witwatersrand district, dipping, 
as they do, in a southerly direction, occupy the northerly side of a 
synclinal fold and come to the surface again in the Heidelberg dis- 
Fic. 5.—Underground photograph at the Durban-Roudepoort-Deep Mine, Wit- 
watersrand District, Transvaal, showing old workings from which the ore has been 
removed. ka 
trict, some thirty miles southeast of Johannesburg, and on the Vaal 
River still farther south. More or less gold mining has been carried 
on in these more southerly districts, but much less extensively than 
in the Witwatersrand district. On the Witwatersrand the gold 
formation can be traced along its strike for over sixty miles, and at 
either end it disappears beneath younger strata. The claim is made, 
however, that it has been traced with the assistance of borings for 
over one hundred and sixty miles, and that there is more or less 
evidence of its extent, though interrupted by faults and covered by 
more recent strata, for over three hundred miles. So far, however, 
