The Stone Ages of South Africa. 179 



only hard rock is a silicisied superficial material (surface quartzite), 

 and the implements are of the harder, finer-grained, and more trans- 

 lucent portions of this recent deposit, as near the Victoria Falls. 

 Around Barkly West the large implements, such as occur in the 

 gravels, are of diabase, and many of them have probably been (or 

 else could have been) made almost iji sitic. Small ones are, again, 

 of agate or quartzite (from Dwyka boulders or from the Vaal Eiver 

 gravels). Now and then one comes across a flake of chert obtained 

 from the Kaap Plateau, or of brown jasper from the Asbestos 

 Mountains, for these two materials are eminently suited for imple- 

 ment manufacture. Indeed, such yellow jasper implements (small 

 size) have been found away from Prreska and Griqua Town, close 

 to Hope Town, Potfontein, Britstown, Vosburg, &c., whither they 

 must have been carried. 



On stepping off the diabase on to the Dwyka conglomerate and 

 shale, the material of the implements changes, though now and then 

 one of diabase is found miles away from any outcrops, e.g., one 

 near Secretaris (between Kimberley and Schmidt's Drift). Around 

 every hill of dolerite are found implements made of black lydianite 

 formed through the alteration of the Dwyka shales by the igneous 

 intrusion ; they are especially numerous near Wolve Dam, W. of 

 Kimberley, but are abundant all along the first dolerite escarpment 

 from Warrenton to beyond Van Wyk's Vlei. 



Implements of lydianite occur also to the N.W., but whether they 

 have been carried there or made from pebbles obtained from the 

 gravels of the Orange, Brak, Eeit, and other rivers cannot be 

 decided. 



In Prieska and Kenhardt, upon reaching the granite area, the 

 latter rock only furnishes white quartz, which is not very suitable 

 for working ; hence the natives appear to have travelled southwards 

 to the outcrop of the Dwyka conglomerate, where there is an infinite 

 variety of material to choose from. The northern edge of the 

 Dwyka, all along the Kaaien Butt, is a good locality for implements, 

 which are mostly made of quartzite or of jasper (from the Griqua 

 Town series). These implements are found in an area which, 

 though waterless, is characterised by small "pans," and, as far as 

 I have been able to judge, there appear to be no spots which have 

 been untraversed by the natives, for implements can be picked up 

 even in the driest and most- uninhabitable parts of the districts. 



Where the Kheis quartzites crop out, the implements are by 

 preference made of that rock, and around Prieska and Griqua Town 

 on the belt of brown jaspers) of the local material. 



