PRE-CAPE ROCKS OF THE NORTH OF THE COLONY 107 



ary minerals, cherty silica and calcite. The breccias 

 and tuffs are dark green rocks with large and small frag- 

 ments of lava in them. Round grains of quartz, felspar 

 and jasper of considerable size, like the grains in the 

 quartzitic grits, are usually seen in these rocks. 



There are also conglomerates in this group, contain- 

 ing rounded boulders of lava as well as rocks older 

 than the Lower Matsap beds. These conglomerates in- 

 dicate local unconformities and the subaerial waste of 

 the lavas. 



Together with the volcanic rocks and conglomerates 

 the Middle Matsap beds include a great thickness of 

 quartzites and grits, many of them just like the normal 

 Matsap quartzites, but there are also white and green 

 varieties. 



The thickness of this group is not less than 4,000 feet, 

 near OJif ant's Hoek, the locality where they are best 



exposed. 



The Upper Matsap Beds. 



These rocks form the main range north and south of 

 the valley cut through the Langberg by the Matsap 

 River, and probably also the greater part of the Koranna- 

 bergen (Plate III.X They consist almost entirely of 

 purplish quartzites and grits, with a smaller thickness 

 of gritty sericitic rocks, but there are no slates. Isolated 

 pebbles of quartz and red jasper occur in these beds, but 

 conglomerates seem to be absent. 



The thickness of the Upper Matsap beds must be 

 some thousands of feet, but as large folds are visible in 

 various places in the Langebergen where transverse 

 sections can be seen on the sides of kloofs the same beds 



