1871.] STOW — VAAL-RIVER DIAMOjS'D-GRAVELS. 15 



along the present river-vallej'-s, in the unstratified gravels and 

 other deposits described above. On the other hand, how near these 

 rocks ajjproach the diamond-deposits on the northern side, and what 

 may be the exact position of the original matrix from which the 

 diamonds were really derived, have yet to be determined. 



Dr. Voysej, Geologist to the Trigonometrical Survey in Southern 

 India, has stated " that the matrix of the diamonds produced in 

 Southern India is the sandstone breccia of the clayslate formation." 

 As some of the formations in India are closely allied to those of 

 Southern Africa, it would be interesting to ascertain whether any 

 rocks similar to those mentioned by Dr. Voysey are to be found 

 either in the extensive range of the Quathlamba, or in any of its 

 offshoots. 



The same authority further states " that the diamonds found in 

 the alluvial soil are derived from the debris of the above rock (sand- 

 stone breccia), and have been brought thither by some torrent or 

 deluge, and that no modern or traditional inundation has reached to 

 such an extent," 



In considering the probable agency that has operated in Southern 

 Africa in producing these vast accumulations of gravel, it may be 

 asked, in the first place, have these gravels been laid down by com- 

 mon fluvial action, assisted and increased by floods and rain-storms, 

 such as those at present in operation ? The deluges of rain that 

 sometimes accompany heavy thunderstorms in this country turn 

 every stream, in every ravine, into a dangerous torrent, and the 

 rivers into impetuous floods, that tear away every thing before them, 

 and frequently discolour the sea for many miles with the floating 

 sediment they have brought down with them. But in examining 

 the results of these inundations — the deep and abrupt chasms they 

 have worn, the assorted gravels they have left, the direction and 

 position of the boulders, and the finely laminated mud or clay — there 

 can be no mistaking the agency by which they were effected. With 

 regard, however, to the diamantiferous deposits now under considera- 

 tion, there are many characteristic features about them that cannot be 

 satisfactorily accounted for by reference to such an agency. The 

 extensive unstratified boulder-gravels, such as are found at Dia- 

 mondia, Hebron, and many other places, — the unstratified gravelly 

 drift, with clay and boulders, as at Pniel — irregular patches and 

 mounds of boulders, — the boulder-clays, and the confused manner in 

 which they are intermingled throughout the entire length of this 

 river-valley, have made all whose opinions I have been able to 

 obtain declare that such heterogeneous accumulations could not have 

 been formed by South- African river-action under its present con- 

 ditions. If laid down by this agent, the deposits would certainly 

 have shown a greater regularity ; the silt would have exhibited a 

 regular interlamination of its clays, sand, or gravel as the case might 

 be, such as may be found in the present deposits of the Fish river, 

 in which are imbedded ardmal and other remains that tell of their 

 recent origin. So also these vast accumulations, had the same con- 

 ditions existed, would have contained organic remains indicating the 



