Deposition of Gold in Smith Africa-. — Czyszkowski. 313 
It is not necessaiy to dwell longer on this subject. Our aim 
was to show the possible formation of metalliferous thalwegs 
and ' niveaux." In 1876 we pointed out the existence of met- 
alliferous thalwegs,* and we have bad occasion in our works 
on iron ores to cite some remarkable ferriferous thalwegs. 
We will quote finally the opinion of the wise geologist and 
practitioner, Mr. A. Parran, who expresses himself as follows: 
"Another class of stratified deposits owes its origin to 'ni- 
veaux 1 of mineral water which has spread through a porous 
stratum comprised between two impervious beds, and has 
mineralized this stratum like an ordinary vein." On the sub- 
ject of the Triassic arkose, Mr. Parran speaks as follows, in 
the work we have just cited: "Some geologists have thought 
that the metallic constituents of this arkose were contempo- 
rary with the sediments. This is extremely unlikely. This 
gravelly deposit is usually quite coarse and seldom has a 
thickness of more than 10 meters. It was probably deposited 
in a short space of time and in agitated waters. Under such 
conditions it would be difficult to account for local and highly 
crystalline mineralization with copper pyrites, with galenite, 
barite and fine needles of carbonate of lead." 
General geological sketch of South Africa, Age of the gold 
deposition. 
What has taken place in South Africa? To what geological 
epoch shall we attribute the deposition of gold? What was 
the position of the strata when the mineral waters came? 
What kind of deposits have been produced? 
Southern Africa forms part of a very vast ancient continent 
which emerged at the end of the Carboniferous period and 
comprised the massifs of Brazil, Madagascar, the Indies and 
Australia, and which was broken up at a later period by greai 
continental depressions. 
Four geological formations arc recognized there : The "prim- 
itive terrane" composed of gneiss, mica sehists and rocks sim- 
ilar to those of Europe surrounds the granitic massifs. 
The "formation of Swaziland"' distinctly developed in the 
•• de Kaap" district consists of slaty or talcose schists, of san d- 
*Minerais de fer en Algerie et considerations generales sur les gise- 
ments metalliferes, 1876. Bulletin de la S< i«-i«'-t «'• scientifique el litter 
a ire d'Alais. 
