Deposition of. Gold in South Africa. — Czyszkowski. 321 
Now as to the question of the rolled pyrites. Its presence 
■seems to us more difficult of explanation on the marine hypo- 
thesis than on the supposition that it was deposited subse- 
quent to the conglomerate. In short it seems as though the 
pebbles of pyrite would have been inevitably crushed and 
pulverized at the bottom of an agitated ocean and in the 
midst of quartz pebbles. In a bed of conglomerate already 
formed, however, where the circulation was gentle, the pyrite 
as it was formed would be dragged and carried into the sin- 
uous courses which the mineral waters followed between the 
quartz pebbles or the silicified areas already mentioned. The 
formation of this rolled pyrite would depend upon the rapidity 
with which the water flowed, the dip of the strata, and the ex- 
istence of larger or smaller cavities in the conglomerate and 
around the pebbles. 
Orogenic and metalliferous phenomena of South Africa. 
Analogy with the South of Spain. 
It seems to be established to-day that at epochs of orogenic 
disturbance internal phenomena are produced in the following 
order : 
1. Folding, elevation, subsidence, fracturing. 
2. Great subsidences. 
3. Wide-spread intrusion of eruptive rocks. 
4. Strong Hows of heated mineral and metalliferous waters 
often preceded, as we believe, by a sort of subterranean 
moraine of hot mud which sometimes contains ores, and some- 
times diamonds as at the (ape. Such would be the complete 
series of orogenic phenomena of which the formation of ore 
deposits would be the final term. 
Now to sum up the phenomena of South Africa: In the 
tirst place east- west folds were formed which affected the 
lower Carboniferous ; then occurred an important intrusion 
of eruptive rocks, and finally came the advent of metalliferous 
mineralizing agencies. Some dislocations, faults and d} r kes 
must have preceded the deposition of the Karoo. 
From this standpoint the gold deposits are of hercynian age 
as in Australia where the veins cut the Archean, Cambrian, 
Silurian and Devonian, all of which are much folded; but 
they always stop at the coal terrane which covers them un- 
conformably. 
