58 Transactions of the South African Philosophical Society. 



period mentioned the folding reached its maximum, but the earth- 

 movements must have continued, though with less intensity, during 

 a considerably longer period. 



The ridge of pre-Karroo rocks, which extends from Zululand to 

 a point on the coast a little north of Port St. John's, is one along 

 which hardly any folding has taken place. But it is very probable 

 that the rocks which are exposed along it formed part of an old 

 surface in pre-Karroo times which extended south-eastwards, and 

 formed again during the Stormberg period a land surface, now buried 

 beneath the waters of the Indian Ocean. The forces which affected 

 the level of this old land surface are probably distinct from those 

 which caused the foldings in the Zwartebergen. 



There is much probability that during the deposition of the rocks 

 of the upper portion of the Karroo system earth-movements 

 affected the earth's crust on three sides, namely, west, south, and 

 south-east, though not necessarily at exactly the same time, or with 

 the same degree of intensity. 



It is probable that at the commencement of the deposition of the 

 Molteno beds, these foldings had already profoundly modified the 

 old land surface, and consequently affected the position of the shore 

 line of the Karroo lake. We find that there is a sudden change in 

 the character of the beds both palseontologically and lithologically. 

 The various labyrinthodonts and dinosaurs, whose remains are so 

 abundant in the uppermost portion of the Beaufort series, are 

 practically unrepresented in the Molteno beds. The brilliant colour- 

 ing of the softer rocks of the Beaufort series is entirely absent in 

 the higher division, and instead we meet with grey, blue, or black 

 mudstones and shales, with occasional coal seams. 



The fossils which are found in these beds are of ferns such as 

 Thinnfeldia, Tceniopteris, and Calliptericlium, cycads such as 

 Phoenicopsis and Schizoneura, while fragments of silicified wood 

 belonging to coniferous trees are abundant in some of the 

 sandstones. 



That the land surface on which these plants flourished lay 

 considerably to the south and south-east of the Drakensberg is shown 

 by inferences drawn from the following considerations : (a) The 

 condition of the plant remains ; (b) the development of the beds in 

 this area ; (c) the petrographical characters of the beds ; each of 

 which will have to be considered in turn. 



(a) It has commonly been stated that the Molteno beds must 

 have been formed close in shore on account of the very perfect state 

 of preservation of the fern leaves, but let us see what evidence can 

 be obtained from the beds in this area. 



