66 Report S.A.A. Advancement of Science. 



Generalising, it may be said that about Newcastle and Dann- 

 hauser the ratio of the unaltered coal is 2 ; in the Hatting Spruit. 

 Dundee and Wessels Nek districts, 3.5; somewhat less, say 2.5, 

 about Elandslaagte, while on the Grey town Coalfield the coal is 

 anthracitic, the ratio being about 10 to i. 



It may be said that in the Utrecht district the ratio is about 

 2,5 to I, and near Hlobane about 4.0. 



About Somkeli nearly all the coal is anthracitic, and the ratio 

 may be put at 10, but 8 miles further inland, where the limit of 

 the decidedly tilted strata is reached, semi-bituminous coal has been 

 found. At Ntambanana the ratio is about 5 to i. 



As regards ash it may be said that on the Klip River Coalfield 

 from Newcastle to Wessels Nek the percentage is about 12, but at 

 the southern end of the coalfield, Wessels Nek and Elandslaagte, 

 where a few collieries work the upper seam, the percentage is some- 

 what higher. On the Greytown Coalfield there is about 15 per cent, 

 of ash. In the Utrecht district the coal is exceptionally clean, the 

 figure being about 8, while in the Vryheid district the average may 

 be put at 12, the same as on the Klip River Field. From Nongoma 

 we have a sample giving a lower percentage of ash than any other 

 South African coal I am aware of. At Somkeli the average mav 

 be about 15.0. On the Ntambanana and Umlalazi fields the coal is 

 usually very dirty. 



It seems clear, when consideration is given to the way in which 

 the carbon ratios and the percentages of ash and sulphur change 

 as the seams are followed from district to district, that there have 

 been general influences affecting the seams over large areas, apart 

 from purely local influences such as igneous intrusions. Probably 

 those general influences, .at least in the Klip River, Utrecht, and 

 Vryheid districts, were original, that is to say, attendant on the 

 conditions of deposition. 



On the Zululand coast the pressure and perhaps heat accom- 

 panying tilting and faulting of the strata observed in that portion of 

 the Colony probably have affected the seams. 



Near Greytown the alteration is not improbably due to pressure 

 also, though the seams are nearly horizontal, as the conditions appear 

 to resemble on a large scale those observed on a small scale at the 

 Impati Mountain, near Dundee. In that isolated mountain the coal 

 seams lie almost horizontally at a level about 300 feet higher than 

 the same seams in the surrounding country. It seems clear from 

 inspection of the slope between the seam? and the dolerite sheet 

 forming the top of the mountain, that the overlying dolerite is too far 

 above to account for alteration of the coal, and while a borehole put 

 down to a depth of 156 feet below has shown no igneous rock, yet 

 the coal is anthracitic, the ratio of fixed carbon to volatile hydro- 

 carbons being 10.6 to i. I attribute the alteration of the seams 

 to the pressure which has raised the mountain and seams above the 

 surrounding country. 



