1871.] STOW VAAL-EIVER DIAMOND -GEAYELS. 11 



locality*. It is situated about twelve miles from the river, aud is 

 about 100 feet higher than Pniel. The boulder-clays and gravels 

 which are found nearer the course of the river appear to be wanting 

 here. In many places the uppermost stratum is a red marl, largely 

 impregnated with calcareous tufa ; in others, the tufa takes the place 

 of the marl. Below this is a stiff red clay, called " Braakgrond " 

 (fallow ground). Both these vary very much in thickness. 



Beneath the clay is a deposit which has been described as a de- 

 composed trappean (?) rock. This is full of angular fragments of 

 many of the constituents of the other deposits, besides diamonds and 

 innumerable small garnets. (See Nos. 13, 14, 15, in Appendix.) 

 This stratum is twenty feet thick, and rests upon " clay-slate "(?). 

 It has been described as out-poured volcanic rock, now decomposed ; 

 and the pan itself has been termed a " crater" ; but this idea does 

 not receive the least support from an examination of the deposit itself. 

 Mr. Ella informs me that the floor of the pan is composed entirely of 

 " clay-slate " [hard shale ?], and that in it no fissures can be traced 

 through which an out-pouring could have taken place. The so-called 

 " volcanic-ash " is merely a dark soil, strongly impregnated with cal- 

 careous tufa. The sharp, angular, fragmentary condition of most of 

 the rocks found in the deposit above mentioned seems to indicate 

 that the stratum in which they are now found could not have been 

 their original matrix. Had it once been a molten mass, as has been 

 suggested, these imbedded fragments would certainly have borne evi- 

 dence of the intense heat to which they had been subjected. Again, 

 in some portions of the diggings at the Pan these strata are said to 

 bear unmistakable testimony of their being sedimentary rocks. My 

 brother informs me that he has found leaf-impressions and plant- 

 stems : unfortunately none of these have been preserved. 



At a depth of seven feet from the surface, at one spot fragments 

 of Ostrich egg-shells and some Bushmen-beacls, made of the same sub- 

 stance, have been found, intermixed with a small univalve shell. 

 To explain the position in which these were discovered, a suggestion 

 has been ventured that, as the molten (?) mass contracted in cooling, 

 cracks and fissures were formed, and a subsequent flow of water has 

 washed these remains into the openings thus caused, and there 

 buried them. Ancient relics of the same kind were found even at a 

 greater depth at Jager's Fontein ; and I have seen similar traces of 

 the primitive race of Bushmen obtained in other parts of the country, 

 from beds of gravel fifteen feet below the surface ; I cannot, there- 

 fore, understand how the hypothesis above given can be supportedf. 



The characteristics of the Du-Toit's Pan deposits differing greatly 

 from those nearer the river, no satisfactory explanation can be given 

 until a careful analysis has been made of them. 



Inferences. — In examining the foregoing sections of the gravels, it 



* See Mr. Gr. S. Higson's notes on its shales and dykes, quoted in the Geol. 

 Mag. February 1871, p. 52.— T. R. J. 



t A small piece of Ostrich egg-shell, and several small flakes of agate, one of 

 which has been used, probably in making beads, or perforated disks, of egg- 

 shell, was found by me on examining a parcel of this gravel from Du Toil's 

 Pan.— T. R. J. 



