158 Geological Society. 



fade away gradually in those directions which are not thus limited. 

 The conclusion was, that the depolarization is the result of strain, and 

 that the perlitic fission is due to the same cause. It was also sugges- 

 ted that the development of the crystals may in some cases account 

 for this strain, while in other instances similar evidence of strain is 

 seen in perlitic areas where no crystal is visible. Other details 

 concerning perlitic and spherulitic structure were also discussed. 



3. "Sketches of South- African Geology. No. 1. A Sketch of the 

 High-level Coal-field of South Africa." By W. H. Penning, Esq., 

 F.G.S. 



In this paper the author gave a sketch of the High-level Coal- 

 field of the Transvaal and the neighbouring region. This coal-field 

 was described as extending 400 miles from north to south, with an 

 average breadth of 140 miles, so that its area is about 56,000 square 

 miles. The tract consists of an elevated plateau forming the " High 

 Yeldts " of the Transvaal and the plains of the Orange Free State. 

 It slopes away to the north-west, and is scarped to the south and 

 east by the heights known as the Stormberg and Drakensberg 

 mountains ; nearly all the principal rivers of South Africa take 

 their rise in this tract of land. The coal-bearing beds forming the 

 plateau rest unconformably in the north upon deposits probably of 

 Upper Palaeozoic age, described as the Megaliesberg beds. In the 

 south-west the Lower Karoo beds underlie the coal-beds, also un- 

 conformably. The beds of the high grounds consist above of sand- 

 stones, called the " High Veldt beds " by the author, and below 

 of shales, for which the name of " Kimberley beds " is proposed, 

 after the chief town of Griqualand West, in which district they form 

 nearly the whole surface. These two series are conformable, and 

 generally lie horizontally. In the shales coal occurs only in minute 

 patches ; the seams of coal are interstratified with the sandstones, 

 into which the shales pass up gradually, and which sometimes in- 

 clude thick-bedded grits and conglomerates. Both shales and sand- 

 stones contain interstratifications and numerous dykes of trap, 

 which have rarely produced much alteration in the sedimentary 

 beds, from which the author concludes that the eruptions were 

 subaqueous and contemporaneous or nearly so. Owing to the 

 persistent horizontality of the rocks, the mountains and valleys are 

 merely carved out of the plateau, so that the thickness of the de- 

 posits is easily measured. The author gave 2300 feet as the mini- 

 mum thickness of each series. By a comparative section it was 

 shown that the coal-bearing sandstones (" High Veldt beds ") are 

 the " Upper Karoo " of Stow, and the " Stormberg beds " of Dunn. 

 The " Kimberley beds " are the Upper Karoo beds of Dunn. 



In the latter part of his paper the author noticed briefly the 

 different localities where coal has been found, namely, Newcastle, 

 Lange's Nek, the Lebelelasberg mountains, near New Scotland, 

 several places on the High Veldt, Wemburg, Brandfoote, Cornet 

 Spruit, Burgersdorf, and Indwe, twenty miles east of Dordrecht. 

 The most northerly point of the Transvaal where coal has been found 



