200 THE BEAUFORT BEDS 



Divisions ; they consist of sandstones, shales, and mud- 

 stones. 



The sandstones are usually light yellow in colour and 

 are of two kinds, a rather loose-grained rock that forms 

 thick bands of strata in the Nieuweveld area and the 

 Midlands, often giving rise to plateaux and terraced 

 features, and a finer grained rock which is in thinner 

 beds and which usually weathers in rounded lumps with 

 a red or brown crust. The first variety is called "de- 

 fining sandstone," 1 and the second "intermediate sand- 

 stone," for owing to the difference in the weather- 

 resisting qualities of the two rocks the thick sandstones 

 cap the larger terraces, while the intermed'ate sandstones 

 make smaller ledges on the mountain sides. The 

 sandstones are often false-bedded and may have their 

 surfaces ripple-marked. 



The shales and mudstones are usually dark blue or 

 greenish, but are sometimes deep red and purple in colour; 

 they are commonly less fissile than those in the Dwyka 

 and Ecca series. Concretionary nodules and lenticular 

 layers of brown weathering blue-black limestone are 

 abundant, as in the Ecca, but often contain small veins 

 and pipe-like rods of pink or white chalcedony. From 

 the fact that both the limestone and chalcedony often 

 permeate the bones of fossil reptiles they seem to have 

 been closely connected in their origin with the presence 

 of organic matter. These nodules weather out of the 

 shales in great numbers' and can be seen along the 

 railway between Groot Fontein and Beaufort West. 



i G. c., i., p. 15, 



