218 THE CAVE; SANDSTONE 



line, zircon, hornblende and white mica are also pre- 

 sent. 



Generally the rock is white or cream-coloured on ex- 

 posed surfaces, but often it is pink or red and sometimes 

 pale blue ; frequently it shows a peculiar mottling. It 

 is invariably fine grained and in a few localities its cen- 

 tral portion is practically a mudstone. Lithologically it 

 is in no way different from many of the sandstones of 

 the Ked beds, except in its finer texture. Generally 

 speaking, the grain of the sandstones becomes finer as 

 one passes from the Molteno beds to the Cave sandstone. 

 In Elliot the Cave sandstone is fully 800 feet thick, but 

 it thins out to north, east and west, seldom exceeding 

 300 feet in the Stormberg, Basutoland, or Griqualand 

 East. At certain places, as in the north-west of Elliot 

 and in the northern part of Matatiele, the Cave sand- 

 stone is not present ; it thins out owing to denudation 

 which took place just before the volcanic outbursts, so 

 that the lavas of the volcanic group rest directly upon 

 the Eed beds. In Barkly East the Cave sandstone is 

 very often split up by intercalations of lava and volcanic 

 ash. 



Fossils are rather rare in this rock, the only finds in 

 Cape Colony being a Dinosaur, Thecodontosaurus skirto- 

 podus (Seeley), 1 and a crocodile, Notochampsa istedana 

 (Broom), 2 while a band of black shale in the sandstone 

 at Siberia (Wodehouse) yielded Estherice, small decapod 

 Crustacea, and wings of orthopterous insects. Casts of 



!H. G. Seeley, Ann. Mag. Nat. Hist., Series 6, xiv., p. 411, 1894, 

 originally called Hortalotarsus. 

 2 K. Broom, G. M., p. 582, 1904. 



