64 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [May 1 894, 



having been described from other English coal-fields. Those noted 

 by Mr. Ratcliffe were principally of quartzite, but boulders of 

 granite have also been found. The principal facts to notice are, 

 that the rocks are foreign to the district, that the boulders are 

 isolated, and occasionally even striated (?), and that they seem to be 

 waterworn and rounded. Sometimes they occur in the bed of coal, 

 but more frequently at its junction with the overlying rock. Some 

 importance attaches to these boulders, both on account of the general 

 rarity of pebbles throughout the Coal-measures and also because of 

 the speculations as to the possible transporting agent. 



It is certainly a curious fact that, if a few hundredweights of 

 rock are found in an isolated position in any of the sedimentary 

 series, the action of ice is sure to be invoked to account for the pheno- 

 menon. This, for instance, is what Mr. Spencer did in his short 

 notice ' On Boulders found in Seams of Coal,' though we may well 

 believe that transport by the roots of trees or floating vegetation of 

 some sort is an equally good, if not, indeed, a more probable expla- 

 nation. It has been suggested that, in the case mentioned by 

 Mr. Ratcliffe, the boulders may have come from some of the pre- 

 Carboniferous conglomerates of the North of England or of Scotland. 

 As the boulders have all the appearance of having been dropped 

 quietly upon the top of the coal, this would imply some depth of 

 water overhead, whatever may have been the agent of transportation. 

 In the Carboniferous Limestone of the neighbourhood of Dublin, 

 Prof. Ball has lately pointed out that angular fragments of granite 

 and other hard rocks have been found. Whilst rejecting the view 

 that they had been transported by ice, he maintained that they need 

 not necessarily have been carried by land plants, but that they 

 might have been torn from the sea-floor by marine algae. He cited 

 the case of a sandy beach at Youghal, where the shore is strewn 

 with limestone-fragments which had been conveyed by seaweeds 

 thrown up after storms from submarine banks. Attention was also 

 drawn to Anson's mention of the occurrence of seaweeds loaded with 

 stones far out at sea. 



Some interesting facts in connexion with coal-seams were 

 recorded by Mr. Hendy in his short paper on a ' wash-out ' in one 

 of the Derbyshire collieries, the nature of the phenomena being 

 aptly illustrated by a series of sections drawn to scale. It has fre- 

 quently been suggested that such ' wash-outs ' are due to faulting, 

 but in this instance, at least, such can hardly have been the case, 

 since the underclay and underlying sandstone are undisturbed, 



