166 Dr. F. n. Hatch — Geological History of South Africa. 



Wales, where a group of Coal-measures over 230 feet thick and 

 comprising from 20 to 40 feet of coal is sandwiched in between the 

 erratic bearing horizon of the ' Lower Marine Series' and the similar 

 horizon of the Upper Marine Series. There appears to be indicated 

 in these facts a recurrence of a glacial epoch separated by a milder 

 interglacial period. Professor Penck, however, to whom I showed 

 specimens of these later breccias in borehole cores from the 

 Vereeniging Coalfield, thought they probably represented a rewash 

 or remanie of the true Dwyka. With regard to the age of the 

 Transvaal coal, the occurrence of Sigillaria Brardi at Vereeniging 

 supplies a link with Europe, and on this evidence Seward ' assigns 

 the beds to the Permo-Carboniferous period, and suggests that the 

 commingling of Sigillaria species with the Glossopteris flora indicates 

 an overlapping of two distinct botanical provinces. 



A recurrence of the conditions suitable for the formation of coal 

 deposits took place at a much later epoch in the Karroo period, 

 namely, at the beginning of Stormberg times (Molteno Beds). 

 Between the two horizons there are some 7,000 feet of strata in the 

 geological column, 5,000 feet of which are made up of the Beaufort 

 Series, which requires no special mention here, except for the 

 abundant occurrence in it of the remarkable labyrinthodont and 

 dinosaur remains. The bones of these animals must have been 

 washed into the lake by rivers. 



At the top of the Stormberg Series, and consequently occupying 

 the highest position in the system, are the basic lavas and ash-beds 

 of the Volcanic Group. The interstratification of ash-beds and lava- 

 flows with sandstone points to some subaqueous eruption ; but the 

 bulk of the later flows were subaerial, and the accumulation of such 

 a vast pile of volcanic material — it is some 4,000 feet thick — 

 determined the watershed of the Drakensberg as it exists to-day 

 in Basutoland and the Eastern Province of Cape Colony. Many 

 of the vents by which the eruptions took place have been found,^ 

 cutting through the Cave Sandstone, by the Cape Geological Survey ; 

 but Mr. Schwarz is of the opinion that fissure eruption also played 

 a part in the formation of the volcanic beds. 



It is interesting to note that the remarkable series of lavas 

 occupying the so-called Springbok Flats in the Transvaal, and 

 known as the Bushveld Amygdaloid, has been found by the 

 Transvaal Survey to overlie sandstones which are considered to h& 

 of Karroo age, and has been provisionally referred to the Stormberg 

 epoch. ^ There is certainly a remarkable resemblance in the 



1 A. C. Seward : Q.J.G.S., 1897, p. 322. , 



2 An interesting account of the geological history of these eruptions is given by 

 Mr. du Toit in a paper on " The Forming of the Drakensberg": Trans. S. Afr. 

 Phil. Soc, vol. xvi, pt. 1 (1905), p. 65. See also "Report on part of the Matatiele 

 Division, with an Account of the Petrography of the Volcanic Rocks," by E. H. L. 

 Schwarz: Geol. Comm. Rep. for 1902, p. 11 ; Capetown, 1903. Also "Geological 

 Survey of Elliott and Xalanga," by A. L. du Toit: Geol. Comm. Rep. for 1903, 

 p. 109 ; Cape Town, 1904. 



» E. T. Mellor : Transvaal Geol. Surv. Rep., 1904, p. 31 ; Pretoria, 1905. 

 Also Trans. Geol. Soc. S. Afr., vol. viii (1905), p. 37. 



