324 Bevietvs — Geology of the Cape of Good Hope. 



and other writers on Soutli African stratigraphy not being recognized 

 as separate divisions. 



TLe Mahnesbury Beds consist of micaceous slates, fine compact 

 quartzites, phyllites, and mica schists, as predominant rocks, with 

 bands of crystalline limestone and beds of sheared conglomerate. 

 Ottrelite schists are not uncommon in the series from the Hex River 

 to Swellendam. The intrusive rocks are granite, quartz-porphyry, 

 and diabase, considerable areas being shown on the map between 

 St. Helena Bay and Mahnesbury and around Paarl and Stellenbosch. 

 The granite is a coarsely porphyritic biotite granite ; segregation 

 veins are numerous and form considerable masses. The granite 

 often shows distinct evidence of shearing. 



Between the Mahnesbury Beds and the overlying rocks a great 

 unconformity is everywhere noticed. The Table Mountain Sandstone 

 Series on Table Mountain, though lying flat, is described as having 

 been subjected to considerable earth movement, as shown by the 

 presence of vertical cleavage and occasional shearing. In the 

 mountains beyond Mitchells Pass and Hex Eiver, and in the Kloofs 

 and Passes of the Zwarteberg and Langeberg, magnificent examples 

 of the twisting and curving to which the Table Mountain Sandstone 

 has been subjected are seen. The Table Mountain Sandstone 

 consists of coarse sandstones and quartzites, with subordinate bands 

 of shale ; no fossils have been found. 



The Bokkeveld Beds, which conformably succeed the Table 

 Mountain Sandstone, consist of sandstones and shales, but the latter 

 play a much more important part than in the Table Mountain 

 Sandstone Series. Many fossils of Devonian facies are found. 



The Bokkeveld Beds pass up into another sandstone and shale 

 group with bands of quartzite, called the Witteberg Beds in the 

 report. These correspond to the Zwarteberg Quartzite Series of 

 other writers ; the alteration of name being necessary as the 

 Zwarteberg Mountains are found by Mr. Rogers to consist of Table 

 Mountain Sandstone. The only fossils found in the Witteberg group 

 are plant remains and the curious markings called Spirophyton, 

 of doubtful organic origin, but said to be very characteristic of 

 this group. 



The Table Mountain Sandstone, Bokkeveld and Witteberg 

 Series, are sometimes grouped together as the Cape Formation. The 

 thickness cannot be estimated, but the three groups form a 

 conformable series of quartzites, sandstones, and shales, several 

 thousand feet thick. 



The Dwyka Series and Ecca Beds are described as conformable 

 to the Witteberg Group. This is an important result, as the Dwyka 

 has been generally described as unconformable to the Witteberg 

 Group. Considerable interest is also attached to the discovery by 

 the Commission of strata of Dwyka and Ecca age around Worcester, 

 to the south of the Worcester-Robertson fault, showing the further 

 extension southwards of these beds than was hitherto expected. The 

 presence of Gangomopteris in the beds at Worcester places this 

 discovery beyond dispute. 



