GEOLOGY OF THE SOUTH AFRICAN REPUBLIC i 
occur also to a considerable extent in the granite. Schenck con- 
siders that the quartz veins are intimately connected in most 
cases with interbedded sheets of greenstone, sometimes altered 
into schists, and that the greenstone ‘“‘appears to be the mother- 
rock proper of the gold.” They appear to resemble the gold 
veins of the Appalachians in that they are mostly parallel in 
dip and strike with the stratification (foliation?) planes, or cross 
them at a slight angle, and are nevertheless true fractures and 
often contain fragments of the country rock. Furlonge speaks 
of quartzite-like bands, which, resisting erosion, stand out on the 
surface in ridges and are called ‘“‘bars.”’ He considers them to 
be the result of silicic replacement, and says the principal gold 
deposits are found in or near these bars, but always in the prox- 
imity of some eruptive rock. Often instead of gold they carry 
deposits of iron oxide of great extent. The gangue of the veins 
is quartz, and, besides gold, much iron pyrites, some sulphides 
of copper, antimony, arsenic, lead and zinc occur. 
The rocks of this formation stretch northward over 80 kilo- 
meters from the steep descent of the Drakensberg, along the 
eastern border of the high plateau, forming the Murchison 
range, and constitute the country rock of the De Kaap, Komati, 
Selati, Little Letaba and Smitsdorp districts. They also occur 
between Pretoria and Johannesburg. They are considered to be 
of Silurian age, partly from indistinct fossils remains, but more 
from stratigraphic correlation with beds underlying uncomform- 
ably the Cape sandstones in the Cape Colony, which have been 
determined to correspond most nearly to the European Silurian. 
The Cape formation, so-called because supposed to correspond 
in age with the Cape sandstones of the Cape Colony, overlies 
uncomformably the Swasi-schists, and is in turn unconformably 
overlaid by the beds of the Karoo formation. It contains the 
gold-bearing conglomerates. Its beds are sometimes upturned, 
even quite steeply, but are not contorted, compressed or dynamo- 
metamorphosed to such an extent as are the Swasi-schists. No 
fossils have yet been found in its beds, but from its relative posi- 
tion, it is supposed to be either Devonian or Lower Carboniferous. 
