Proceedings of the British Association. 24/ 



extending for a considerable distance ; it appears from its mineralogi- 

 cal character to have been a mechanical or aqueous deposit. 



Mr. Murchison remarked that the discovery of a coal-field as old 

 as the Devonian system, although new, had not been improbable. 

 Mr. Sedgwick and himself had discovered coal-plants in the Devo- 

 nian rocks of the Rhenish provinces. — Sir H. De La Beche stated 

 that the coal-plants were the earliest types of terrestrial vegetation 

 yet known ; in Devonshire they were found in that part of the culm, 

 which was the equivalent of the millstone grit. Conglomerate con- 

 taining boulders of coal in Pembrokeshire had been described by 

 Mr. Logan, who referred to them in proof of the enormous period of 

 time which must have elapsed between the deposition and consolida- 

 tion of the beds of coal from which the conglomerates were formed, 

 and the succeeding coal strata. In England haematite usually occur- 

 red in fissures and veins, but there was a bed of it in the Forest of 

 Dean evidently deposited at the same time with the other strata ; and 

 this might be expected from the analogy presented by the extensive 

 deposits of impure carbonate of iron as " bog-ore," still in process of 

 formation. — Mr. Sedgwick observed that the conditions requisite for 

 the formation of coal had occurred in every geological epoch subse- 

 quent to the great coal formation, and he therefore believed that it 

 might have been also formed, and perhaps traces of it still existed in 

 the very oldest rocks. He had examined the workings for haematite 

 at Egremont, and ascertained that in this instance it was not a regu- 

 larly bedded mass, but filled an ancient limestone cavern, the project- 

 ing portions of the roof being water-worn and polished ; he thought 

 it probable that much of the haematite in England had been deposit- 

 ed by aqueous agency in clefts and hollows, at the time of the new 

 red sandstone, when the sea was charged to excess with per-oxide of 

 iron. 



* On the Denudation of South Wales and the adjacent Counties,' 

 by A. C. Ramsay. — The object of this communication was to show 

 the great amount of certain denudations, and the approximate periods 

 at which they had taken place. In South Wales the older rocks are 

 in general terms conformable, indicating quiet deposition. After the 

 deposition of the coal measures, violent disturbances took place, curv- 

 ing and contorting all the strata from the coal measures downwards. 



2 K 



