Bev. M. H. Close — The Shell-bearing Gravels near Dublin. 1 95 



those of the low gravels, as a group (see paper by Prof. Oldham, 

 Journ. GeoL Soc. Dublin, vol. iii. p. 131), and a decidedly less 

 northern fades than the much larger collection of Drift shells from 

 Moel Tryfaen, at 1360 feet elevation. However, it would be scarcely 

 prudent to found any argument on the limited induction that we have 

 been able to make. Two other points seem worthy of notice, though, 

 they may be but accidental : viz. that of Cardiiim edide, which occurs 

 so frequently in the gravels at lower elevations, near Dublin, only 

 one fragment has yet been recognized in the higher accumulations ; 

 and also, that but three univalves have been found, although shells of 

 that class must be generally better able, than others, to withstand 

 rough usage, and therefore more capable of handing down determin- 

 able fragments. Pieces of Cyprina Islandica are the most common, 

 evidently on account of the thickness and strength of that shell. 



What then is indicated by the occurrence of marine Drift shells 

 in those elevated situations in our neighbourhood ? Not as much 

 as might, perhaps, be supposed on first thoughts. We did not need 

 their presence to assux'e us that the sorting and stratification of those 

 elevated gravels and sands was effected by the sea ; for, as Mr. 

 Kelly has pointed out in his paper, it is utterly impossible to refer 

 that to any other agent. And, moreover, those shells do not give 

 us any information as to the character of the marine fauna of this 

 district when the sea covered it so deeply. The gravel, etc., in 

 which they occur is "limestone gravel" (with a slight sprinkling 

 of granite stones), resting on granite hills; this has been carried 

 thither from elsewhere ; and the smashed condition of the shells, 

 and the fact that those fragments, which are large enough to show 

 it, are often well scratched, like many of the pebbles among which 

 they lie, lead to the conclusion that those fragments form, as it 

 were, part of the gravel and have been carried thither along with 

 it, and that, therefore, the animals did not live and die where their 

 remains are now found. (It would seem from the descriptions, 

 especially by Mr. D. Mackintosh, F.G.S., of the Moel Tryfaen gravels 

 and shells, that the same has been the case with the Drift shells of that 

 place.) This conclusion is strengthened by the consideration that, 

 when the sea was up at the level of the site of Caldbeck Castle, the 

 ground would fall steeply down from the very shore-line in all 

 directions to a great depth ; and several at least of the above shells 

 would be without sufficient platform, or suitable habitat, for their 

 subsistence. 



But how were the limestone gravels and the shells carried to their 

 present positions on the granite hills ? Let us note that only a very 

 small proportion of the gravel stones exhibit signs of water-rolling ; 

 they are generally subangular ; many are greatly scratched ■ (these 

 occur more usually in the upper parts of the gravel), and some are 

 quite angular. Again, at Caldbeck Castle, the nearest part of the 

 limestone ground is 2|- miles distant, and 900 feet lower down ; and 

 at Ballyedmonduff pit the nearest part is 4| miles distant, and 800 

 feet lower down ; yet the proportion of limestone and other foreign 

 pebbles, etc., in the gravel at those places is at least 99 per cent. It 



