E. H. L. Schwarz — 'Gold in Cape Colony. 373 



at 700 feet, and traversing the side of the ravine down to 200 feet, 

 with every appearance of its continuing indefinitely. 



I have shown reason to believe that the reefs represent fissures 

 due to a tearing in the rocks as they bent round the end of the 

 granite ; they must, therefore, follow roughly a succession of shells 

 of tension round the end of the granite arm, the actual course of the 

 fissures being directed by the lie of the rocks, which would be 

 stronger in one direction than in another, but the vertical extent, 

 I think, would be independent of the formations, and the fissures 

 traverse any kind of rock strata that may exist in the area of the 

 shells of tension. 



The Table Mountain Sandstone represents a shore deposit, and 

 the Bokkeveld Slates a deeper- water formation. Taking into con- 

 sideration the extent and distribution of these sediments, it is fairly 

 well proved that they must be derived from a continent which 

 formerly existed to the north of where they now lie. This continent 

 we can see emerging from a later covering of Karroo rocks in 

 Namaqualand, Prieska, and the Transvaal, and it contains deposits 

 of minerals of exactly the kind which we find in Knysna, the 

 O'Kiefs copper deposits and the Rand gold-banket, to take two 

 instances. The detritus from this land would naturally carry with 

 it a certain amount of the mineral ores, and they would be deposited 

 along with the bulk of the sediments. There would be a rough 

 sorting according to gravity, the heavier metals, such as gold, lead, 

 and zinc, would tend to come to rest nearer the shore than the 

 lighter ones, such as iron and copper, and I look to this action to 

 explain the presence of the former group in the Table Mountain 

 Sandstone and the latter in the Bokkeveld Slates. 



In regard to the gold and associated metals, it is a well-known 

 fact that sand does not tend to precipitate them, whether carried 

 mechanically or in chemical solution, until the deposit becomes 

 gravelly ; and in the present case, although it is likely that traces of 

 gold might be found in the sandstones on careful analysis, the major 

 portion seems to have come to rest in a consolidated gravel or 

 banket which occurs near the top of the series in this neighbour- 

 hood. Assays give 2 dwt. per ton of gold, and from its extreme 

 hardness there is no possibility of mining this rock unless richer 

 spots can be found. The banket dips under the Bokkeveld Slates, 

 and comes up on the south sides of the inlier, so that it can be safely 

 said to recur as a continuous sheet, dipping some two or three 

 thousand feet below sea-level. In the Bokkeveld Slates pyritous 

 layers occur, but as a general rule I think the ores of iron and 

 copper were distributed fairly evenly throughout the mud that is 

 now represented by the clay-slates : it partly impregnated them in 

 the form of minute crystals and films, and in part has crystallized 

 out in the form of cubes. 



Having now traced the minerals from their original resting-place 

 in the older rocks of the northern continent to the stratified deposits 

 in Knysna, we have to follow the process by which they became 

 leached out and redeposited in the quartz-veins. The circulation 



