1871.] STOW VAAL-PvIVER DIAMOIirD-GEAVELS, 9 



No. 5 is a very dark blue, slate-coloured, gravelly clay, with irre- 

 gularly interspersed boulders ; below this is No. 6, a yellow clay, 

 thickly mottled with patches of calcareous tufa, which has evidently 

 infiltrated into its substance ; and below this is No. 7, a reddish, 

 ochreous, gravelly clay. These rest upon the same rock (" rotten- 

 stone ") as that met with in the Natal Kopje. The hollows of its 

 surface are termed " pockets " by the diggers ; and in these the finest 

 diamonds are said to have been found. 



These gravelly clays seem to be the equivalents of those found 

 above the great gravel-deposit at the above-mentioned kopje. 

 They are also found on the opposite side of the river, at Diamondia, 

 capping the same kind of rock. There are other beds of a very 

 similar character, resting upon the highest of the Hebron gravels (see 

 fig. 2). Continuing this section, a vast accumulation of boulder- 

 gravel (c) is found at rather a lower level. Its width is 300 or 

 400 yards ; shafts have been sunk to a depth of between 30 and 

 40 feet without reaching its bottom. It is quite un stratified; and 

 large boulders are confusedly mixed with it. The upper portion 

 is of a red colour ; but, on digging into it, it gradually becomes 

 lighter below, and more compact. In some parts it has a calca- 

 reous cement. 



On the Hebron side there is also another great deposit of boulder- 

 gravel, at rather a higher level (see fig. 2). This seems to have 

 almost entirely the same cement or matrix as those just mentioned. 



All these gravels contain diamonds, as well as numerous frag- 

 ments of fossil wood (the specimens sent were obtained at c, on the 

 Diamondia side) . Some fragments of fossil bone, found at the same 

 place, have been unfortunately lost ; but, from the description 

 given, they must have been water-worn fragments of reptilian 

 remains *. The pebbles contained in the gravel are illustrated by 

 the specimens sent. See Nos. 10 & 11, from Hebron, and No. 12, 

 from Diamondia, in the Appendix. 



The reddish colour of the upper portions of the gravels at c, c, 

 seems to be most probably due to infiltration from above, as, on pe- 

 netrating into them, the colour soon becomes paler, and gradually 

 disappears. The same may also be said of the lower gravels that 

 have a calcareous cement. 



Prom the lie of the strata, it is probable that these gravels, c, c, 

 rest upon the ancient rocks marked h, h ; but, for want of definite 

 information, I have been unable to show their exact position with 

 reference to each other. These lower rocks are described by some 

 of my friends as " metamorphic " and distinctly showing evidence of 

 stratification, with a dip of about 7° to W.N.W., towards the river 

 on the Diamondia side, and from it on the Hebron side f. 



* I have since seen one of these specimens; it was probably a metapodal 

 bone, 1^ by 1 inch, very much polished. July 6, 1871. 



t I cannot help thinking that the so-called " clay-slate " of the Vaal is very 

 similar to, if not identical with, rocks of the same character in the lower portion 

 of the Great-Fish-River valley, and that an ancient system of metamorphic rocks, 

 most probably connected with those of the Yaal, underlies the strata of the 

 Stormberg basin ; indeed, judging from what I have seen in some of the exten- 



