THE KARROO SYSTEM 195 



wood. On the weathered surface the sandstones are 

 usually yellowish, but some of the finer-grained beds 

 break up into rounded fragments with a thin red crust. 

 The Laingsburg beds have been traced through the 

 country on the south and west of the Klein Eoggeveld, 

 where they form very hilly ground, and at Schoorsten 

 Berg over 2,500 feet of strata are exposed belonging to 

 the lower and middle divisions alone. In the Tanqua 

 Valley the sandstones become much thinner and dis- 

 appear, being perhaps represented by shales farther 

 north. 



The uppermost portion of the Ecca beds in the South- 

 ern and Western Karroo varies considerably in the pro- 

 portions of sandstones and shales in different localities. 

 The sandstones are frequently mottled grey and blue. 

 On the Kraai River, near Turin Plaats, Glossopteris, 

 Gajigamopteris, and Schizoneura occur in hard shales be- 

 longing to these beds. 



In the Eoggeveld and Hantam region the sandstones 

 that are so conspicuous in the country farther south are 

 but slightly developed, and the whole of the Ecca series 

 becomes an essentially argillaceous group, with only 

 thin beds of sandstone intercalated with the shales ; 

 calcareous concretions in the latter now become abun- 

 dant. The thickness of the series diminishes in the same 

 direction, and is probably somewhat over 2,000 feet 

 near Calvinia village. The rocks are well exposed on 

 the Hantam Mountains and on the Roggeveld escarp- 

 ment, of which the former were once a part, having 

 been detached from the main mass by the erosion due 



to the Oorlog's Kloof River. 



13* 



