Vol. 50.] ANNIVERSARY ADDRESS OF THE PRESIDENT. 65 



although in one instance the underclay is seen to have been cut 

 through by the denuding agent. The space of the ' wash-out ' is 

 filled up by sandstone. This is clearly an instance of contempora- 

 neous erosion, and the ' wash-out ' may actually represent one of 

 the river-beds of the fen in which the coal accumulated. In this 

 case one third to one half of the coal is said to have been re-deposited 

 in different places on the sides, the remainder having evidently been 

 carried away, thus pointing to a kind of intermittent action of the 

 water. 



In a paper on the Formation of Coal-seams, Mr. Gresley, from 

 evidence gathered chiefly in the Leicestershire and South Derbyshire 

 coal-fields, is disposed to contest the orthodox view of growth in 

 situ. Without myself venturing to express an opinion upon this 

 point, it seems to me that the experience of mining engineers and 

 others connected with the working of coal is of great importance. 

 It sometimes happens that professional men of this sort, though 

 possessed of valuable information, are unable to put it into a 

 geological form, and require, as it were, an interpreter. But such is 

 not Mr. Gresley's case, and I venture to think that an abstract of 

 his arguments is worthy of attention. 



In considering the relations of the fire-clays to the coal-seams, 

 he points out that such fire-clays, containing Stigmarice and root- 

 like fossils, occur in other positions than that of an underclay to 

 coal; that the thickness of an underclay bears no proportion to 

 that of the coal-seam resting upon it ; and that the underclay is 

 usually divided off from the coal-seam by a true bedding-plane, 

 nor is there any merging of one formation into the other. Secondly, 

 when considering the behaviour of Stigmaria-roots, he points out 

 that a considerable proportion of the underclays do not contain 

 Stigmaria-roots at all, though they seldom fail to reveal the 

 presence of thin, grass-like, fossil markings. But when Stigmarice 

 do occur in the underclays, they do not, as a rule, pass upwards 

 into the coal. Moreover, when erect fossil stems or stools of trees 

 are met with, they are generally either resting upon or at no great 

 distance from the tops of coal-beds ; though the best examples, such 

 as the fossil trees at Clayton and Bradford, have occurred in beds far 

 removed from coal. He concludes that the general absence of erect 

 fossil tree-stems in underclays is an argument against a growth in 

 situ of coal, at ail events from trees. Thirdly, in considering the 

 question of lamination, he asserts that the laminated character of 

 coal affords no evidence that the coal-forming plants grew upon the 



