748 R. A. F. PENROSE, JR. 
The origin of the conglomerates themselves, without reference to 
the gold in them, was doubtless similar to that of many other conglom- 
erates elsewhere, that is, they were formed by the accumulation of 
gravel and sand under watef near shore. It is probable that they 
are of marine origin and were laid down along the shore line of some 
more or less open sea. Later on they were covered by other strata, 
then elevated into a land area, folded and distorted by the dynamic 
action to which the region has been subjected, then more or less eroded 
by atmospheric influences, and eventually left as they are now found. 
As to the source of the gold in the conglomerates, there has been 
much more dispute than as to how the latter were formed. Two dif- 
ferent theories, among the several that have been advanced on this 
subject, seem to have received most support. One of them sup- 
poses that the gold is all detrital, that it was deposited mechanically 
with the pebbles of the conglomerates at the same time as these beds 
were formed, and that it came from the same rocks as the pebbles, 
or at least from adjacent rocks. In other words, this theory supposes 
that the gold-bearing conglomerates are simply old placer deposits. 
The second theory supposes that the gold was brought into the con- 
glomerates after the latter had been formed and probably after they 
had been elevated into land areas, that the conglomerates simply acted 
as pervious strata through which gold-bearing solutions found a 
ready passage, and in which the gold was deposited in much the same 
way as it is supposed to have been deposited in the fissures contain- 
ing it in most gold districts. 
George F. Becker? supports the first theory and believes that the 
gold was deposited mechanically with the pebbles of the conglomerates 
and that it came from the erosion of the same land area, though it may 
have been somewhat changed in position and character by subse- 
quent chemical action. He thinks the conglomerates are of marine 
origin, and that they are in fact simply marine placers, solidified by 
the later deposition of secondary silica. 
Messrs. Hatch and Corstorphine,? on the contrary, believe in the 
second theory, that is, that the gold was deposited from solutions 
1 “The Witwatersrand Banket, with Notes on Other Gold-Bearing Pudding 
Stones,” United States Geological Survey, Eighteenth Annual Report, 1896-7, Part V, 
“Metallic Products and Coal;” pp. 173-77. 
2 The Geology of South Africa, pp. 145, 146. 
