THE WITWATERSRAND GOLD REGION 741 
Leader, are usually smaller but often rich beds. Other less important 
conglomerates are the North Reef, the Middle Reef, etc. 
The Main Reef, from which the Main Reef series has received its 
name, is generally the largest, and ranges from a few feet to probably 
fifteen feet or more in thickness, though usually not of high grade. 
It outcrops along a general east and west course throughout the dis- 
trict, and dips in a southerly direction at angles which are often steep 
near the surface, frequently 80° or more (Fig. 2), and shows a tendency. 
f Fic. 4.—Underground photograph in the Jumpers-Deep Mine, Witwatersrand 
District, Transvaal, showing the gold-bearing conglomerate running diagonally across 
the picture. The speckled rock indicates the conglomerate. 
to flatten in depth, a dip of from 40° down to 20° or less being common 
at no great depth (Figs. 3, 4, and 5). The South Reef lies to the 
south of the Main Reef and is separated from it by intervening strata 
of a thickness of from a few feet to ninety feet or more. It is usually 
somewhat smaller than the Main Reef but is usually richer. It is 
parallel to, and shows the same variations in dip as the latter. The 
Main Reef Leader is a conglomerate bed almost immediately over- 
lying the Main Reef and separated from it by only a few inches to a 
