60 Transactions of the South African Philosophical Society. 



(b) The development of the beds. From the description already given 

 of the various members of the Stormberg series, it will be seen that, 

 although each varies considerably in thickness, the same variation 

 affects them all simultaneously. The maximum thickness of the 

 sedimentary strata is attained in the eastern part of Elliot, namely, 

 4,200 feet, made up as follows : Molteno beds, 1,800 feet ; Eed beds, 

 1,600 feet ; and Cave sandstone, 800 feet. In Molteno and Aliwal 

 North the thickness is only 2,000 feet, and sometimes less, propor- 

 tioned thus: 1,200 feet, 600 feet, and 200 feet. In Matatiele, 

 according to Mr. Schwarz, the two upper members together do not, 

 as a rule, exceed a few hundred feet. 



The conclusions to be drawn from this great thickening of the 

 beds along a line drawn from north-west to south-east is that 

 the old shore line lay somewhere to the south and south-east. As 

 will be seen from the map, Elliot is situated so that sediment could 

 arrive at it from the south-west, south, and south-east, hence the 

 exceptional thickness of the beds thereabouts. 



(c) The petrographical characters of the beds. A petrographical 

 examination of the sandstones in the Molteno beds shows that the 

 material has been derived chiefly from the disintegration of quartzite, 

 granite, and metamorphic rocks. The fine-grained sandstones are 

 built up principally of rounded and angular grains of clear quartz, 

 together with fragments of milk-white or blackish quartz, orthoclase 

 and microcline felspar, garnet, zircon, apatite, tourmaline, and flakes 

 of mica. 



The coarser sandstones are sometimes very quartzose but at other 

 times contain large angular fragments of felspar in a very fresh con- 

 dition, so that the rock may be termed an arkose. At no horizon 

 lower down in the Karroo system are similar beds met with. 



The coarse, gritty sandstones occasionally become conglomeratic, 

 the pebbles consisting principally of vein-quartz and of quartzite ; 

 by the farmer such beds are called " banket," and believed to be 

 auriferous. 



A peculiar feature in connection with the Molteno beds is the 

 occurrence in them of smooth rounded or oval pebbles usually a few 

 inches across, but ranging up to boulders two feet in length. These 

 pebbles are, as a rule, scattered most irregularly through some of the 

 sandstones, for example, in the bed which immediately overlies the 

 coal at Indwe. In the Molteno Division these pebbles are so 

 numerous as to form beds of conglomerate up to a few feet in thick- 

 ness, and on Eomansfontein and Hassiesfontein one of these beds 

 can be followed for several miles." It occurs a little above a seam 



* E. J. Dunn, " Report on the Stormberg Coalfields," p. 17, Cape Town, 1878. 



