1871.] SHAW — DIAMOND-PIELDS OF SOTJTH AFEICA. 23 



■was not deep, and the whole Eiish was soon dug out. These tvpo 

 facts give additional proofs in favour of the recentness of the deposits ; 

 and consequently strong promise that the present river-bed may- 

 prove equally rich. The river Vaal is not a rapid stream. It flows 

 sluggishly from one terrace to another, and falls in its course by a 

 series of rapids at intervals of some miles. It winds about to a con- 

 siderable extent throughout its entire progress. This is in favour of 

 the view that the alluvial gravel has been deposited by the Vaal, as 

 the country is one which the slightest elevation at particular points 

 would alter so as to change the course of the stream for miles. The 

 rapids are caused by basaltic dykes, which may be considered to be 

 kopjes in the process of formation for a future time. Such dykes, 

 moreover, are meanwhile " bars," and prevent the greater part of the 

 material washed down from going beyond them. 



The Isolated Diamond-fields are very different in soil from that 

 of the Vaal Kiver. The surface, instead of being a ferruginous loam, 

 is in most cases calcareous. The pebbles are by no means many, 

 and they are all angular and not water- worn. 



I have visited the various isolated digging-spots. They are in 

 geological and diamantiferous indications the same. The pebbly mass 

 of the Vaal-Eiver diggings glistens with beautiful agates and crystals 

 of nearly every colour ; but the soil washed and sifted in the isolated 

 diamond-fields is not by any means so attractive. The pebbles are 

 fewer, occasional agates, crystals, abundance of tourmaline and garnet 

 amid a mass of fragments of basalt and pieces of serpentine, all im- 

 bedded in a more or less calcareous soil, which glistens with talc 

 and mica, 



I had been, from the commencement of my study of the diaman- 

 tiferous tracts of South Africa, on the look-out for the primary and 

 metamorphic series. 



I have mentioned the existence of granite in the trap-conglomerate 

 of the Vaal ; and I got hold of a water-worn fragment of gneiss, which 

 also occurs in the same conglomerate, as I afterwards discovered. I 

 found, however, no decided traces of true metamorphic rocks till I 

 examined the diamantiferous pans and isolated places. I collected 

 in the course of one tour specimens of gneiss, chloritic schist, mica- 

 schist, and talcose slate in different digging-spots. I found none of 

 these rocks in situ ; and they no longer exist in connexion with the 

 rock-system of the region, as far as I have been able to ascertain. 



It is necessary, before going any further, to enlarge on the nature 

 of these pans, the detritus drifted to Avhich from surrounding tracts 

 is now being searched for diamonds, and is found to contain frag- 

 ments of the schistose series. 



Du Toit's Pan is the most celebrated of all the diamantiferous 

 pans, and may be taken as a type of the pans of the region. 



I cannot indorse the views of Mr. Wyley in regard to the origin 

 of the salts of these pans — that the saltness has been left to them 

 by the sea, which at some period (he thinks comparatively recent) 

 swept over the whole, or nearly the whole, of South Africa. With 

 reference to his opinion that the land has been gradually elevated 



