PRE-CAPE ROCKS OF SOUTH AND WEST OF COLONY 47 



Fig. 5). It is a peculiar type of rock, with much horn- 

 blende forming ophitic plates enclosing the felspar, the 

 hornblende is colourless and seems to have been formed 

 from augite. The Gamka River, above the Ladismith 

 Road, crosses a dyke of peculiar diabase, in which the 

 rather long crystals of felspar form radiating star- shaped 

 bundles. Beyond a marked hardening of the slates or 

 grits in contact with the thicker dykes, there is little 

 alteration in the sedimentary rocks near them. 



THE FRENCH HOEK BEDS. 



At French Hoek there is typically developed a series 

 of slates, arkoses, pebbly grits and conglomerates, which 

 appear to be younger than the granite and quartz- 

 porphyry intrusive in the Malmesbury beds but which 

 are older than the Table Mountain series. At the 

 south end of the Midden Berg, on the west side of the 

 village, there is a coarse conglomerate, somewhat sheared, 

 and full of well-worn boulders of quartzites, grits, slates, 

 rein-quartz, quartz-porphyry and granite. It dips at a 

 high angle to the north-west and rests upon quartz- 

 porphyry. Similar conglomerates are seen at the ridge 

 to the south of the village. In several localities the 

 strata in contact with the quartz-porphyry consist of 

 jleaved grits and sheared arkoses. The latter are very 

 like sheared quartz-porphyries, and it is often impossible 

 detect any clear line of demarcation between the two 

 ;ks in the field. The quartz-porphyry and granite 

 ippear to have furnished by their disintegration and 

 decomposition a coarse felspathic material which even- 

 tually formed beds of arkose ; the subsequent folding of 



