LOCATION AND STRUCTURE OF CAPE COLONY RANGES 383 



series of shales and sandstones, all of continental origin and including 

 many dikes and sheets of dolerite. The Ecca and Stormberg series con- 

 tain coal; the Beaufort series is famous for its reptiles. 



The floor on which the Cape system rests consists of the Malmesbury 

 slates, regarded as Archean, with intrusive granites, well exposed along 

 the shore at Sea Point, a western suburb of Cape Town, where several 

 of the geologists of our party saw them in an interesting excursion under 

 the guidance of Mr Dutoit, of the Cape Colony Geological Survey. 

 These older rocks were reduced to an essentially plane surface, in the 

 Cape Town district at least, before the deposition of the Cape system, as 

 is proved by the even surface of contact between the two around the 

 northern escarpment of Table mountain. A peculiar feature of the Cape 

 system is the absence of marine fossils, except in its middle member; it 

 has therefore been suggested that the Table Mountain and the Witteberg 

 sandstones are of continental origin, and that they resemble in this re- 

 spect the formations of the overlying Karroo system, for which a fuller 

 statement will be made in a later section. 



The following table summarizes the succession of the formations in- 

 volved. It should be noted that the strata of the Karroo system occupy 

 a large part of the interior highland, or Veld, and therefore far outrun 

 the area of the Karroo district from which their name was taken : 



C Stormberg "\ 



„„ -__ „ I Beaufort I Sandstones and shales. 



Karroo system, 20,000 feet. J „ C 



J Ecca J 



L Dwyka tillite and shales. 



Witteberg sandstones and shales. 

 Cape system, 10,000 feet. J Bokkeveld sandstones and shales. 



f 



/ Table Mountain sandstones. 



ANALOGY OF THE CAPE COLONY RANGES WITH THE ALLEGHENIES 



The east and west ranges, of which the Zwartbergen and the Lange- 

 bergen are the most conspicuous members, are of especial interest to 

 American geologists because of their resemblance in several respects to 

 the Allegheny mountains of Pennsylvania and Virginia, the middle sec- 

 tion of the Appalachians. The heavy strata involved are in both cases 

 chiefly of pre-Permian age. Forces of compression have in both the 

 Alleghenies and the Cape Colony ranges crowded a great part of the area 

 of the strata concerned into long subparallel folds, with overturns and 

 overthrusts directed inland, but have left the farther interior area prac- 

 tically undisturbed, this area constituting the Allegheny plateau in one 

 case and the highland of the Veld in the other. Hence it may be in- 



