386 LOW LEVEL GRAVELS 



seen along the Breede River below Swellendam. It is 

 often difficult to separate the higher of these from the 

 high gravel plateaux, and hard ferruginous rocks and 

 even quartzites may be found on them, but they may 

 often be distinguished from the plateau gravels by the 

 finding of pieces of the quartzitic or ferruginous gravels 

 amongst their pebbles. The Breede River terraces have 

 gravels containing such pebbles and boulders derived 

 from the older deposits, originally of a similar nature. 



In some parts of the Swellendam, Riversdale and 

 Mossel Bay Divisions the gravels met with far from 

 the mountainous ground often contain large pebbles 

 derived from the conglomerates belonging to the Uiten- 

 hage series. These pebbles were well rounded, and were 

 probably in much the same condition as they are to-day, 

 before they reached their present position. The same 

 is the case in other districts, such as Oudtshoorn, where 

 the Uitenhage conglomerates occur. The abundance of 

 these derived pebbles in positions where an explanation 

 of their presence would be very difficult on the supposi- 

 tion that they were brought directly from the original 

 source of the rocks of which they are made, is at places 

 very striking. 



Near the mouths of many of the rivers of the south 

 and south-east coasts there are sandy deposits which 

 extend to a considerable depth below the beds of the 

 rivers. At the Bitou River 1 the green sands containing 

 many marine shells, including large numbers of Crypto- 

 don globosus, which is now comparatively rare in the 

 adjacent sea, were pierced to a depth of forty-seven feet 



1 Schwarz, G. C., iv., p. 61., 



