72 Report S.A.A. Advancement of Science. 



buted, and of a uniform character, and such beds certainly could 

 hardly have any claim whatsoever to being ranked as gem-bearing 

 alluvial beds. The deposits are of comparatively recent origin in 

 the geological record, and although of no value commercially, are 

 of interest from a scientific point of view, in that they may mark the 

 fact of the po'jsibility of the occurrence in South Africa of an Ice 

 Age in Pleistocene or recent times, and thus far more recent 

 than the one already acknowledged by geologists as occurring in 

 Permo-Carboniferous Times, the previous presence of which was 

 known from the recognition of such a series of strata as the Dwyka 

 Conglomerate and other traces of former ice action. Although the 

 South African climate may not have been so cold then as to have 

 given rise- to large icebergs and icefields, such as are to be found in 

 many countries at the present day, yet the intensity of the cold may 

 have been sufficiently great to have caused accumulations of ice and 

 vast accumulations of snow on the highlands and Western Borders 

 of Natal, fringing on the heights of the Drakensberg. Such masses 

 of snow would, no doubt, move down into the surrounding valleys 

 and lower regions of a more temperate nature in climate, carrying 

 with them in the form of a ground moraine a vast quantity of 

 detrital products : or a rise in temperature produced by climatic 

 changes in these higher regions may have produced at times an 

 increased liquefaction of the surrounding masses of ice and snow, 

 and thus have given rise to torrential waters, whose violence and 

 transporting powers may have eftected the deposition and formation 

 of such alluvial beds in the places mentioned. I do not anticipate 

 that the degree of coldness then was similar to that found within 

 the arctic and antarctic regions at the present day, nor that there 

 was an equality of temperature in proceeding from the interior to 

 the coast, but what I do venture to suggest is, that the climate in 

 pleistocene or recent times in South Africa was considerably 

 colder than what it is at the present time, and that there was pro- 

 bably a rise in temperature in proceeding from the heights of the 

 interior to the coast line, owing to the proximity of the seas. One 

 might be led from the occurrence of the boulders above mentioned, 

 ^to suspect that they are what are known as perched blocks or 

 erratics, and mark such a period ; but they certainly appear to have 

 had little connexion with an Ice Age in South Africa, except, of 

 course, in so far as those are concerned which are found within the 

 alluvial beds. The latter specimens show a different kind of out- 

 ward weathering to those on the hillsides, being of an extremely 

 light yelowish brown colour, and the effects of the decomposition 

 extends further into the parent mass than is the case with the others. 

 Besides, they are extremely small in average size, compared to the 

 others, and are always found accumulated at definite spots through- 

 out the deposits. This appearance shows that they have suffered 

 from the effects of water for a long time, and have gathered and 

 been puddled about. It is more than likely that those which are 

 lying on the summits nnd slopes of the kopjes have at one time 

 been portions of the upward prolongations of the dykes previously 



