12 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [jSToV. 8, 



seems evident that tlie diamantiferous deposits of the Vaal are not 

 the resnlt of any single or abrupt operation of nature, as some have 

 suggested, either in the shape of some " great debacle," or volcanic 

 eruption, but rather that, for some enormous ]Deriod of time, there 

 were long-continued causes at work, occasioning a distinct sequence 

 in the different wide-spread accumulations of boulder-drift, clays, 

 and gravels of which they are composed. 



At Hebron and Diamondia this is clearly the case : there we find, 

 first, the unstratified cemented gravel and boulders, as shown at d, 

 in fig. 2 ; the terrace-like deposits at c, c, were deposited probably 

 at the close of the same period. Then followed the boulders and 

 gravelly clays, marked J^os. 1, 2, 3, 5, 6, and 7. All these in their 

 turn have undergone great denudation, the lateral drainage from 

 the more level country having divided them into separate terrace- 

 like mounds and isolated kopjes, the intermediate portions having 

 been carried away, and a rearrangement of portions of the gravels 

 {e, f, and g) having taken jJaee at a lower level in the ancient 

 trough of the old rocks h, h. These latter gravels are much more 

 sandy than the more ancient drifts, large portions of their clayey 

 elements having necessarily been washed out of them during the 

 period of readjustment. Pinally, this last deposit {e, /, and g) has 

 been cut through by the river in forming its present chahnel. 



The question now arises. Were the more ancient boulder-gravels 

 derived from a local source, or have they travelled from a distance ? 

 And, if so, what is the probable direction whence they came ? 

 and by what agency were they transported to the localities where 

 they now are ? 



Although the original locality of the true matrix of the diamonds 

 found in them has not been discovered, still there can be little 

 doubt that a largo portion of the constituents of these deposits has 

 come from great distances. 



At this point, the tell-tale fragments of fossil wood, worn and 

 polished as they are, become most interesting and valuable evidence. 

 Zones of fossil wood extend almost the entire length of the Storm- 

 berg* ; and magnificent specimens are found in many places on the 

 northern side of these mountains. I have been told, by the Hon. 

 Theophilus Shepstone, that, in his journeys through Kaifirland, he 

 has traced the existence of large quantities of fossil wood along the 

 Quathlamba or Draakensberg range to Natal. I am not aware, how- 

 ever, that these zones have been found stretching to any great distance 

 northward, or in a north-westerly direction from these ranges, to- 

 wards that part of the diamond-bearing fields now under con- 

 sideration. 



Place of Origin of the Drifts. — It was always believed in the Cape 

 Colony that the country rose towards the far interior in a succession 

 of steps ; but the results of Mr. Graham's barometrical observations 

 show this to be, to a certain extent, incorrect. From the coast to 

 the ridge of the Stormberg, however, it holds good, and along a line 

 within a certain distance of the western face of these mountains : 

 * Quart. Journ. GeoL Soe. vol. xxvii. p. 523 &c.— T. E. J. 



