488 Annals of the South African Museum. 



'2. This question lias been partly answered above. In the Cape 

 the Molteno Beds are a local phase corresponding to a certain type 

 of climate and certain geographical conditions which enabled coarse 

 pebble-beds, finer sandstones, and carbonaceous shales to accumulate 

 in a huge subaerial delta over a plain situated at the foot of an 

 ii|ir;iised land mass to the south. In the High Veld of the Transvaal 

 there is no corresponding mass of sediment. During the deposition of 

 the Beaufort Beds in the south of the Union, the Transvaal area was 

 subjected to erosion and denudation (deposition only taking place 

 within certain basins), the sagging of the geosyncline in the south 

 |iossiblv being compensated by a rising of the northern area. This 

 period of erosion, however, came to an end at some point during 

 Stormberg times; and in some of the basins formed on the unequal 

 land surface debris accumulated, to be soon covered by thin shales 

 and the Bushveld sandstone. There is evidence to show that warping 

 and sagging took place in the region north of Pretoria during Karroo 

 and post-Karroo times, which would account for the overlaps round 

 the margins of such basins as have been preserved. The basins, in 

 fact, owe their preservation to the sagging which took place. In 

 spite of minor differences visible in specimens from different places 

 the liiishveld Sandstone is of so uniform a character that it is 

 reasonable to suppose that the patches that remain are but relics of 

 a once more widely-spread layer that stretched up into Southern 

 Rhodesia. Like the Cave Sandstone it was subaerial and probably 

 mainly aeolian ; and once the basins were tilled up by the driven 

 and blown sand, the material spread out to cover a larger and 

 larger surface. We cannot estimate its maximum extent, nor con- 

 jecture what peaks of older rock stood up above the sandy levels. 

 AVe shall note later that there seems to be a lateral change from 

 a line-grained "loess-like" deposit to a somewhat coarser, rounded 

 desert-sandstone. In this area the basal conglomerates may be the 

 equivalent of the Molteno Beds - - they are equally tbe result of the 

 action of torrential rains able to produce temporarily streams strong- 

 enough to carry fair-si/ed pebbles: while in the basal part of the 

 reddish clays north-west of Pienaars River Station the occurrence of 

 a very thick compound seam of coal lends colour to this suggestion. 



The climatic conditions which gave rise to the Red Beds of the 

 Cape were shortlived in the Transvaal; and the climate rapidly 

 changed to one comparable with that reigning in Cave Sandstone 

 times further south; the onset of such conditions was possibly ear- 

 lier in the north than in the south. As a general conclusion, the 

 further north one goes from the Cape area the greater is the evi- 



