Deposition of Gold in South Africa. — Czyszkowski. 311 
After a folding of the crust and the emission of rocks, the 
entire zone of disturbance is usually affected and invaded by 
these mineral waters. Whatever be their origin, it is perfectly 
Avell known and demonstrated that ore deposits are produced 
"by mineral waters. These mineral waters have circulated in 
the earth's crust either ascending under pressure or as surface 
waters. 
The circulation of surface waters is perfectly demonstrated 
and easily understood. The water of rains or that produced 
by melting snows percolates downward into the rocks either 
by means of fractures and fissures or through porous strata 
such as sands, sandstones or conglomerates. Sheets of sub- 
terranean water are produced. When an impervious stratum 
retains and deflects the waters there is formed a water level. 
If this water level is held between two impervious beds we 
have a flowing spring or sheet of water. Thus at Paris, which 
is situated in the center of concentric strata elevated at their 
outer edges, a well sunk to a depth of 600 meters encountered 
a flowing stream of water which has become classic. The sink- 
ing of the well at Grenelle was undertaken in 1834 for a scien- 
tific experiment. Five years later, in 1839, the depth of 480 
meters had been reached without finding water and the advis- 
ability of continuation to greater depths was debated. Arago 
advised further boring to the depth of 600 meters and the fa- 
mous water was found at 548 meters. The flow was estimated 
at nearly 4 million liters of clear water per 24 hours, with a 
temperature of 28 degrees. The well at Passy is 580 meters 
deep. That at the Say refinery is 600 meters and that at La 
Chapel le 718 meters. 
All these springs were found in the green sands of the Cre- 
taceous and in some places formed columns of water spouting 
up to a hight of 40 meters above the level of the Seine. This 
bed of porous green sand outcrops more than 100 kilometers 
from Paris, at an altitude of at least 100 meters. 
In various countries drill holes have brought up fish and 
particles of swamp plants; and fresh water shells, which could 
have no other origin than in valleys, lakes or ponds several 
hundreds of meters away, have been brought up from depths 
of more than 50 or 100 meters. All these facts prove the 
subterranean circulation of surface waters. We may recall 
