252 Scientific Proceedings, Royal Dublin Society. 



pendent ice-sheet, which overflowed through St. Greorge's Channel, 

 and passing across the south-east corner of Wexford, spread along 

 the south coast of Ireland at least as far as Power Head in County 

 Cork. The evidence in the neighbourhood of Dublin tends to 

 show that this ' Irish Sea Ice ' attained its maximum development 

 shortly before that of the centre of Ireland. 1 This is borne out 

 by the sections on the south coast at Dungarvan and Ballycroneen 

 (County Cork). In the former place, the marly boulder-clay of 

 the Irish Sea Ice is overlain by that which came from the north ; 

 and in the latter, by a boulder-clay similar to that seen around 

 Cork, and which the striae show to have been laid down by ice 

 moving from west to east across the Harbour. This ice 

 apparently had its centre of dispersion in Kerry or West Cork, as 

 striae in a similar direction have been observed in the valley of the 

 Lee at Macroom and Grougane Barra, and there is a gradual 

 swinging round from an easterly to a southerly direction as we 

 proceed along the coast from Cork to Baltimore. 



It will be seen from these considerations, and on consulting the 

 map (PI. XXXI.), that the direction of the ice-motion on the south 

 coast was generally off-shore. The deposits, owing to their posi- 

 tion in the lee of the cliff, were thus protected from erosion by the 

 ice, the action of which, as pointed out above, was comparatively 

 feeble over the greater portion of the area. 



In order to give an idea of the mode of occurrence of the pre- 

 glacial 2 deposits thus preserved, we shall, before proceeding to a 

 general account, describe a few characteristic sections. The first, 

 that in Courtmacsherry Bay, is typical of those areas which the 

 inland ice alone appears to have invaded. The second, in Bally- 

 croneen Bay, is of interest as being within the debatable ground 

 which appears to have been first occupied by ice from the Irish 

 Sea Basin. The third furnishes a proof of the pre-glacial age of 

 the old rock-platform, independent of the mere superposition of 

 the boulder-clay. 



1 This result is in accordance with Mr. Lamplugh's conclusion that the centre of 

 greatest accumulation over the British Isles shifted westward and south-westward 

 during the period of glaciation. See " Geology of the Isle of Man " — Mem. Geol. 

 Surv. U.K., 1903. 



2 The term ' pre-glacial ' is used throughout the paper to signify ' prior to the 

 deposition of the boulder-clay of the area in question.' 



