316 
The American Geologist. 
May, 189$ 
at some points is overlain by patches of the Karoo containing* 
beds of coal. The central part of the Rand, which has been 
the scene of the most extensive exploitations for gold, has a 
regular structure. The strata strike east-west and dip south 
about 75°. 
Toward the west on the Randfontein side and toward the 
southwest at Buffelsdorn in the Kleksdorp district as well as 
in the eastern portion near Modderfontein and toward the 
south in the district of Heidelberg, at Nigel, there is less uni¬ 
formity but the gold bearing strata are known to be rich and 
are exploited. The strike of the strata and of the reefs be¬ 
comes northeast-southwest, and they have no longer the steep 
dip that they possess in the northern part of the Rand. 
Within the area which includes Kleksdorp, Randfontein, 
Johannesburg, Modderfontein and Heidelberg has been assum¬ 
ed the existence of a basin of lacustrine terranes in which the 
beds of auriferous conglomerate were deposited. It is now 
recognized that this idea was erroneous, and the more reason¬ 
able idea of a marine formation has been adopted. M. de 
Launay presents the theory of a northeast-southw T est synclinal. 
Mr. Jules Gamier holds to the idea of inclined deposits still 
possessing approximately their original position.* 
Whatever be the true theory of these basins or synclinals 
the grand and rich central region of the principal exploita¬ 
tions for gold shows that the rock strata and reefs which at 
the surface dip 75° to the south are not inclined more than 
30° at considerable depths. Must we admit with Mr. de Lau¬ 
nay that these moderately inclined strata have an indefinite 
extension? We do not see why the horizontal portion of the 
bottom of the trough and an upward slope toward the south 
may not soon be discovered; and we believe that such will be 
the case. We would not be surprized if the bottom of this 
trough were already reached at certain points in a mine named 
for a bright future the “Village main reef,” situated on the 
extension of the reefs exploited in the “City and Suburban,” 
the “Jubilee,” the “Salisbury” and the “ Vemmer.” 
An examination of the sections of these mines and particu¬ 
larly those of the Jubilee and Salisbury seems to indicate that 
*Mr. Jules Garnier’s article will appear in the Memoires de la Societe 
des Ingenieurs Civils. 
