Vol. 67,] WORCESTER, ROBERTSON, AND ASHTON (CAPE COLONY). 703 



In the southern part of Cape Colony, the Witteberg Series seems 

 to pass conformably into the Karroo System, though towards the 

 north a marked overlap occurs, so that the Karroo rocks rest 

 unconformably on all the older systems. There is thus evidence 

 of a differential movement, which does not seem to have noticeably 

 affected the rocks of the south-west. 



The Dwyka and Ecca rocks of the Worcester district resemble 

 in all essential details those of the Karroo area in the north, 

 and were undoubtedly formed in direct continuity with them ; 

 and their present isolated position is a result of post -Karroo 

 disturbance. 



Since the composition and characters of the Enon Conglomerate 

 constitute one of the most important subjects treated of in the 

 present paper, the consideration thereof must be deferred. 



All the rocks up to and including the Karroo System have 

 in this area undergone important disturbances and dislocations, 

 and even the Enon Conglomerate shows unmistakable evidence of 

 earth-movement of considerable intensity ; so it is evident that in 

 recent times the region has been subjected to great disturbance, 

 and the prevalence of hot springs, as at Montagu and Brand Vley, 

 suggests that activity is even now by no means extinct. 



III. Physiography of the Area. 



The region under investigation is one of very varied topography, 

 presenting many features of interest from the standpoint of the 

 physical geographer, and it illustrates with especial clearness 

 the relation between scenery and geological structure. There is 

 perhaps no part of the world where the scenery is so closely 

 dependent upon the character and arrangement of the underlying 

 rocks as in the western portion of Cape Colony; and here there has 

 been a complete absence of complicating factors, such as glaciation 

 or recent submergence and re-elevation, which have played so 

 important a part in modifying the topography of many northern 

 regions. Hence the effects of a powerful and long-continued 

 process of denudation can be effectively studied. 



The area as before denned lies wholly or almost wholly within 

 the drainage-basin of the Breede Kiver, one of the largest streams 

 of Cape Colony. It is bounded on the north by the Hex-Biver 

 Mountains and the Langebergen, which form one continuous range 

 trending roughly from west-north-west to east-south-east, and only 

 broken through at intervals by some of the larger tributaries 

 of the Breede, such as the Hex Biver and the Kogmans River, 

 both of which rise to the north of the principal range. These 

 mountains attain an average height of some 5000 feet, the culmi- 

 nating peak, Matroosberg, having an altitude of about 7400 feet. 

 The southern slope of the range is exceedingly steep, and this has 

 a most important bearing on some geological features of com- 

 paratively recent origin. In front of this great escarpment comes 

 a narrow strip of foot-hills, varying in width from 1 to 5 miles 



