204 Proceedings of the Royal Irish Academy. 



affected by the subseqxient invasion of the ice. But it becomes necessary to 

 account for the absence of such beaches from the interior of the country, or at 

 any rate of traces of them churned up with glacial detritus, and this can only 

 be done by supjjosing that ice had already accumulated in the lowlands in 

 sufficient quantity to bank out the sea during the epoch of submergence. 

 Maxwell H. Close' justly insisted that the marine shells were brought along 

 with the gravels, and that the animals to which they belonged lived and died 

 somewhere else ; and he invoked floating ice as the agent of theh- accumu- 

 lation. British geologists, however, outside the south-east of England — that 

 is to say, geologists working in areas where glacial phenomena are of high 

 importance — have been more and more inclined to the -sdew that such high- 

 level gravels with marine shells have been uplifted by moA'ements of glacier- 

 ice when it became pressed against rising ground. Whether the Irish Sea 

 ice flowed, as is very probalile, over a raised sea-floor, or whether it 

 displaced the sea before it as it advanced, it must have gathered a con- 

 siderable quantity of yielding material into its lower layers. Such an instance 

 as that of Cora Island goes far to convince the observer as to the power of 

 movements within the ice. If we witness even 100 feet of uplift in recent 

 times, 1,000 feet seems nothing improbable diu'ing the climax of the Ice Age. 

 Local subsidence maj' still be invoked to account for special cases, and the well- 

 known deposits imder Macclesfield, now concealed, but occurring at a general 

 height of 450 feet above the sea, may represent a raised mid-glacial beach 

 over which ice subsequently rode.- The present height above the sea, 

 moreover, of the deposits on the Dublin Mountains is not likely to be 

 precisely that at which they were laid down out of the ice. The slope of the 

 lowland may have been eased for the advancing glacier. Yet few who ha^'e 

 been fortunate enough to visit Scandinavian and Arctic lands will see 

 anything improbable in the views of P. F. Kendall, G. W. Lamplugh,' and 

 others, who have lu-ged that the Irish glacial gravels with marine shells have 

 been raised through the body of advancing ice. 



On this ■s'iew, which many of us have been slow to accept, the higher 

 deposits would probably be of later date than those nearer the sea-level. 

 The ice still remaining on Cora Island may be taken as a model ; it reached 

 the obstacle formed by the island, and the intraglacial material from lower 

 levels was pushed up over its back. 



The melting of the ice below has left this material, the red shelly 



' "The SheU-bearing Gravels near Dublin," Geol. Mag., 1874, p. 197. 



' See discussion bj- T. J. Pocock, " Geology of the country aroimd Macclesfield, Congleton, 

 Crewe, and Middlewich," Mem. Geol. Survey, Eng. and Wales (1906), pp. 83-87. 

 ' " Geology of the country around Dublin," Mem. Geol. SuiTey (1903), p. 45. 



