THE CAPE SYSTEM 133 



long and narrow strips of slate in which the charac- 

 teristic fossils are not easily found. 



In the Cederbergen east of Clanwilliam the shale band 

 is about 300 feet thick, but some 100 feet of rock at 

 the base of the band consist of greenish blue or red- 

 dish mudstone without lamination, containing scattered 

 pebbles and boulders, which show flattened and striated 

 surfaces like those of glaciated boulders. 1 The boulders 

 are made of quartz, quartzites, sandstones, red jaspers, 

 amygdaloidal diabase and granite. The random dis- 

 tribution of small and large pebbles through a fine- 

 grained matrix, together with their scratched surfaces, 

 are evidence that the rock is a tillite, or hardened till or 

 boulder clay, of glacial origin. In many respects it 

 resembles the Dwyka tillite seen in the Karroo a few 

 miles to the east of the Cederbergen. The best localities 

 for seeing the outcrops of the Clanwilliam tillite are the 

 road over Pakhuis Pass, the slopes of the mountains on 

 Klein Vlei and Lange Kloof, and Bosch Kloof on the 

 south-west or downthrow side of the Augsburg fault, 

 which a little farther north causes the Bokkeveld beds 

 to lie against the sandstone of the Table Mountain series 

 below the shale band. The length of the lines along 

 which these glacial beds have been followed near Clan- 

 william is twenty-three miles. 



The base of the glacial beds is exposed on the farm 

 Bosch Kloof, where there is a gradual passage from the 

 usual coarse quartzitic sandstones with scattered white 



1 For detailed descriptions see G. C., v., p. 79 ; T. S. A. P. S., xi., p. 236, 

 1902 ; ibid., xvi., p. 1, 1905 ; and Schwarz, The Journal of Geology, xiv., 

 p. 686, 1906. 



