48-4 Annals of the South African Museum. 



mainly of speculation unless the sediment is near the region of erosion 

 and other conditions are favourable for preserving the mineral con- 

 stituents of the original rock or rocks in an unaltered condition. 

 Chief interest centres around the probable physiographic changes of 

 the parent land-mass. 



A general survey of the Stormberg sediments reveals a sudden in- 

 terruption of deposit of shales and fine-grained sandstones which took 

 place throughout Upper Beaufort times and the displacement of that 

 type of sediment by a series of grits, coarse-grained sandstones, con- 

 glomerate bands, and somewhat irregular large lenses of shales (some- 

 times coaly). This type was followed by a series of sandstones, 

 reddish in colour and becoming progressively liner-grained, inter- 

 bedded with red clays; and that by the line-grained Cave Sandstone. 

 This succession can be profitably contrasted with that of the Siwaliks 

 of the Himalayas as described by Medlicott and Blanford (1879). 

 They say "Sandstone immensely preponderates in the sub-Himalayan 

 deposits, and is of a very persistent type from end to end of the 

 region and from top to bottom of the series. Its commonest form 

 is... of a clear pepper and salt grey, sharp and line in grain, ge- 

 nerally soft, and in very massive beds. The whole Middle and Lower 

 Siwaliks are formed of this rock, with occasional thick beds of red 

 clay and very rare thin, discontinuous bands and nodules of earthy 

 limestone, the sandstone itself being sometimes calcareous and thus 

 cemented into hard nodular masses. In the Upper Siwaliks conglo- 

 merates prevail largely: they are often made up of the coarsest shingle, 

 precisely like that in the beds of the great Himalayan torrents ... The 

 mountain torrents are now in many cases engaged in laying down 

 great banks of shingle at the margin of the plains, just like the 

 Siwalik conglomerates; and the thick sandstones and sandy clays of 

 the Tertiary series are of just the same type of form and composition 

 as the actual deposits of the great rivers." They conclude that the 

 Siwaliks were laid down as a lluviatile outwash from the rising 

 Himalayas. 



We see here that the succession in the Siwaliks is the exact op- 

 posite of that shewn by the Stormberg Beds - - at least to the top 

 of the Red Beds. In the Siwaliks fine-grained sandstones and red 

 clays give place to coarse-grained sandstones, conglomerates and coarse 

 shingle-beds. If Medlicott and Blanford are correct in assigning the 

 Siwaliks to lluviatile deposition from a rising mountain mass, then 

 it may be presumed that the Stormberg Beds are possibly sediments 

 derived from a land-mass slowly lessening in altitude. 



This presumption is further buttressed by certain theoretical con- 



