60 THE KRAAIPAN FORMATION 



miles to Jonker Water in Prieska, where they pass under 

 the Dwyka. Throughout their length the Kaaien heds 

 in these hills seem to be flanked on the south-western 

 side by gneiss, but between the gneiss and the typical 

 quartzite or quartz-schist there is often a zone of 

 schists and gneissose rocks, some of which are mainly 

 composed of quartz while others approach gneiss in 

 their composition ; it is probable that these intermediate 

 rocks have been formed by the addition of granitic 

 material to the sediments. Similar mixed rocks have 

 been observed on the north-east flank of the hills and 

 also round the granite masses within them. 



The Kaaien beds have been invaded by both large 

 masses 'and small veins of granite, and also by rocks that 

 have been converted into hornblende-schists. 



The thickness of these beds must be considerable, 

 though owing to folding and faulting, and to the pres- 

 ence of great intrusive masses of gneiss, no attempt to 

 estimate it would be of service at present. The gradual 

 narrowing of the main belt occupied by these beds as it is 

 followed south-eastwards is probably due to the north- 

 west inclination of the axes of the folds and to the fact 

 that the present surface passes obliquely through this 

 folded mass and the gneiss which surrounds it. 



2. THE KRAAIPAN FORMATION. 



In Maf eking and Vryburg there is a peculiar formation 

 composed principally of banded magnetic quartzites, 

 cherts and jaspers, sericite-, chlorite-, and calcareous 

 schists, hornblende schist, serpentine, diabase and 

 quartz-porphyry. 



