104 THE MATSAP BEDS 



The series has been divided into three groups, but 

 where the middle group is concealed or is absent there 

 is always uncertainty as to the horizon of the strata. 

 The divisions are : 



Upper Mat'sap beds, chiefly quartzites, grits and 

 sandstones. 



Middle Matsap beds, or Hartley Hill group, dis- 

 tinguished by the presence of volcanic rocks. 



Lower Matsap beds, quartzites, shales and conglo- 

 merates. 



The Hartley Hill group has only been found on the 

 east side of the Langberg and is best exposed in the 

 neighbourhood of Olifant's Hoek in the Kuruman 

 Division. 



The Lower Matsap Beds. 



The base of the Matsap series is seen in the Ezel 

 Rand of Prieska, along the eastern side of the eastern 

 foothills of the Langberg, and in the Matsap and 

 Gamagara ridges. Possibly also the western foot hills 

 of the Langberg are made of the lower beds, and part 

 of the Korannabergen, but these hills rise from the 

 Kalahari sand which effectually conceals the rocks of 

 the plain. 



The chief features of the lower beds are the presence 

 of conglomerates and shale bands in addition to quart- 

 zites and grits. In the Gamagara ridge the underlying 

 rock is the Blink Klip breccia, and the basal conglomer- 

 ate of the Matsap group is there crowded with fragments 

 of the breccia and deeply coloured by haematite derived 

 from it. A rather similar conglomerate crops out in the 



