76 THE KORAS SERIES 



merates and sandstones, the position of which in the 

 stratigraphical series is doubtful. They are called the 

 Koras series from their occurrence on the farm of that 

 name. Only the outcrops on the right bank of the river 

 have as yet been examined, but the series certainly ex- 

 tends over part of the Kenhardt district. The length of 

 the largest area of this formation traversed by the river 

 is fourteen miles ; towards the north the Koras rocks 

 disappear under the sand of the Kalahari. A smaller 

 area on Kameel Poort and Kooi Kopjes covers some ten 

 square miles. 



The eastern limit of the Koras beds is formed partly 

 by a fault with a northerly course, along which they 

 are thrown down against the Wilgenhout Drift beds, 

 and partly by an intrusion of enstatite-diabase which 

 has a devitrified glassy base. This rock has risen along 

 the fault, and a similar intrusion has taken place along 

 another fault with a north-north-west course limiting 

 the outcrops on Koras, where the sediments of the 

 Koras group have been considerably altered by the 

 diabase. The western fault has a downthrow to the 

 north-east, and the Koras beds have been thrown against 

 the Kheis quartzites. 



The Kameel Poort and Kooi Kopjes outlier rests upon 

 the steeply inclined Kheis beds unconformably. 



The Koras beds, though affected by these faults and 

 intrusions, have been disturbed to a very much less ex- 

 tent than the Wilgenhout Drift and Kheis beds, and at 

 a distance from the diabase they have a younger appear- 

 ance than the other Pre-Karroo rocks in the north. 



The lower part of the series consists of lavas and tuffs, 



