PHYSICAL GEOGRAPHY OF THE CAPE COLOXY. 249 



need not be reproduced here ; but the following points arc of general 

 interest. 



It was only in a very few instances that I was able to get a sight 

 of the floor of the coal-seams ; but whenever this was the case, I 

 found nothing below the coal which in any way resembled a " seat- 

 stone " with roots or rootlets. At the Indwe Colliery the coal rested 

 directly on a hard, closely-grained, laminated, micaceous sandstone. 

 There were a few vegetable impressions on the planes of bedding ; 

 but I could see nothing like rootlets. In another case the floor was 

 formed of an irregularly bedded, micaceous, sandy shale ; at Cypher 

 Gat the floor was well-bedded shale ; in neither case could I detect 

 any sign of rootlets. This absence of a seat-stone suggested to me 

 the possibility that the coal was of subaqueous origin. 



There are other peculiarities in the coals w^hich seem to me to 

 lend some support to this view. 



All the coals which have been anal3^zed are extremely impure ; 

 they contain from 21 to 30 per cent, of ash. 



Again, all the coals that I saw are more or less finely laminated. 

 Some of the layers appear to be all coal, often bright and lustrous ; 

 but even the cleanest-looking leaves a large amount of ash when 

 burnt. Other layers are black shale. As far as these two sets of 

 layers go there is nothing to distinguish the South-African from 

 many other coals. But there is a third kind of layer, the like of 

 which I do not recollect to have seen in any but these South- African 

 eoals. The layers of this third class are dull, and each is made up 

 of a number of subordinate laminae, often of excessive thinness. If 

 we split a block parallel to one of these laminae, the surface is so dull 

 and earthy that no one, looking at it alone, would ever believe that 

 he had a piece of coal in his hand : nothing like coal is to be seen ; 

 but the appearance is exactly that of the surface of a bedding- 

 plane of rather dull black shale. It would seem that these layers 

 are complicated in their structure ; that they consist of a large 

 number of very thin laminae of coal, and numerous still thinner 

 films of hardened black mud, which coat the surface of each coal- 

 lamina and separate it from the laminae above and below it. Fig. 1 

 illustrates in a diagrammatic way the structure just described ; (a) 

 are layers of bright coal, (c) are layers of black shale, (6) are layers 

 consisting of very thin alternating laminae of coal and black mud 

 films. 



The finely laminated layers were shown in a very pronounced form 

 in the coal worked at Cypher Gat. Mr. CutteU managed to cut me 

 a section of this coal which was fairly transparent round the edges. 

 The laminae were too numerous to be counted exactly, but at least 

 six were distinguishable in a thickness of -07 millim. ; some of these 

 were again subdivided into subordinate laminae not more than '003 

 millim. thick. In parts the laminae ran remarkably true and 

 rectilinear ; in other parts they were wavy and broken ; but they 

 were everyw^here sharply defined. Some were quite transparent 

 and yellow or yellowish brown (? pure resinous vegetable matter) ; 



Q. J. G. S. No. 174. s 



