264 Report S.A.A. Advancement of Science. 



In colour, in modes of weathering, and in general appearance, the 

 two groups are not alike ; the Matsap beds are, on the average, 

 coarser in grain than the Table Mountain beds, and the purple- 

 mottled tints of the great bulk of the former are foreign to the latter ; 

 the Matsap beds do not give rise to the peculiarly-curved, wind-worn 

 masses of rock, with accumulations of iron oxides and silica in some 

 parts and a loose, sandy texture in others which have been observed 

 in the Table Mountain sandstone, from the Pondoland outcrops to 

 the westernmost exposures in Calvinia. The surface of the Matsap 

 areas is covered with large and small blocks of quartzite, with rounded 

 corners ; the rock breaks down into its component grains much less 

 readily than the Table Mountain sandstone does ; in the Langebergen 

 of Griqualand West the ground on the top of the mountains is hard, 

 sandy soil between the outcrops and boulders of quartzite, while in 

 the Langebergen of the south coast and other mountains made of the 

 Table Mountain series, the interstices between outcrops are filled with 

 loose white or black sandy soil. 



The chief objection to the correlation is to be found in a com- 

 parison of the structural features of the north and south of the 

 Colony. In the south the earth-movements which produced the 

 ranges made of the Table Mountain series took place long after the 

 deposition of the Dwyka series, and there is a sequence of conform- 

 able rocks from the base of the Table Mountain series into the Karroo 

 formation. In the north there is a great gap between the Matsap 

 beds and the Dwyka. Near Piljaar's Poort there is an outlier of 

 the normal northern type of Dwyka till lying between the forked ends 

 of one of the Langeberg group of hills, and one of the chief con- 

 stituents of the boulders is the Matsap quartzite ; there is no doubt 

 that the northern Langebergen were in very much the same condition 

 during Dwyka times as thev are in to-day. They have probably lost 

 something in altitude by denudation, and new valleys have been cut 

 in them, but they stood in the same relation to the older rocks east 

 and west of them as they do now, and they do not appear to have 

 suffered any further crumpling. Except that these earth-movements 

 which affected the iNIatsap beds in the north took place in Pre-Dwyka 

 times, we have no direct evidence of their date as compared with the 

 southern rock-systems, but a further comparison of the geology of 

 the two regions will- throw more light on the question. The Matsap 

 beds are certainly some thousands of feet thick ; four thousand feet 

 can easily be accounted for in the Langebergen, near Pad Kloof, and 

 the top is not known. These beds originallv stretched over a con- 

 siderable part of Hay and southern Bechuanaland, at least as far 

 as the Paling-Gamagara and Matsap ridges, which are outliers of the 

 formation ; a great part of this sheet of rock must have been removed 

 in Pre-Dwyka times, for at Piljaar's Poort the outlier of Dwyka till 

 mentioned above very probably rests upon the Griqua Town beds which 

 crop out in the immediate neighbourhood, between the Dwyka and 

 one of the Langeberg ridges. Now, if the INIatsap beds are taken to 

 be the equivalents of the Table Mountain series, the earth movements 

 that crumpled the northern strata and the denudation which removed 



