420 THE OLDEST SEDIMENTARY ROCKS 



beds have yielded no very definite fossils. In South 

 Africa there is an immense thickness of imfossiliferous 

 strata, the Pre-Cape formations, older than the Devon- 

 ian system, but we are still in complete ignorance of the 

 position of an horizon corresponding to the base of the 

 Cambrian system of other continents. Hence such 

 terms as Pre-Cambrian and Algonkian, which assume 

 the recognition of a Cambrian fauna, should not at the 

 present time be applied to any South African forma- 

 tion. 



The earliest sedimentary rocks recognised in Cape 

 Colony are the Malmesbury beds of the south and west, 

 and the Kheis beds of the north ; whether these two 

 groups are in part of the same age is quite unknown, 

 but they both represent the results of a long period of 

 denudation and concurrent deposition ; where least 

 altered they are chiefly arenaceous and argillaceous 

 rocks, and there are also some interbedded limestones. 

 There is no rock in Cape Colony that has been shown 

 to be older than these two groups of beds ; we know 

 nothing corresponding to the Archaean system of some 

 countries, a formation whose origin is doubtful and 

 which is older than the earliest recognisable sediments. 



Both the Malmesbury and the Kheis series occupy 

 wide areas and have high dips throughout, from which 

 we may conclude that they were strongly folded and 

 at one time formed very considerable mountains. At 

 the present day the hills made of them rarely rise 1,000 

 feet above the surrounding country, and in some cases 

 (e.g., Signal Hill, Groenberg) the prominence of the hills 

 is due more to the former existence of a protective cover 



