Geological Society of London. 127 



Prof. Eamsay, in conclusion, observed that it was well known that the Jurassic 

 and Oolitic beds of Europe must have accumulated in a warm climate around islands 

 and in bays and estuaries. It was, however, difiicult to account for the rivers flowing 

 over such narrow tracts of land as that represented by the central portion of the 

 British islands, having had such important estuaries. The large transported blocks 

 of Old Red Sandstone found in the conglomerates offered another difficulty. He 

 agreed with Mr. Judd as to the impossibility of fixing the age of the main line of 

 faults, as many of them might date back their origin to an earlier period than the 

 commencement of the deposition of the Oolites. The narrow neck of land which 

 intervened between the eastern and western Oolitic beds of Scotland ofi"ered great 

 matter for consideration. With regard to the connexion between the Lias and Trias, 

 he had long regarded the New Red Marl as more intimately related to the Lias than 

 it was to the New Red Sandstone ; and in Scotland the New Red Marl seemed to be 

 absent, and the Lias to be brought into comparatively close contact with what was 

 considered to be the New Red Sandstone, 



IL— January 22, 1873.— His Grace the Duke of Argyll, K.T., F.R.S., President, 

 in the Chair. — The following communication was read : — " On the Glaciation of 

 Ireland." By J. F. Campbell, Esq., F.G.S. 



The author stated that almost the whole of the surface of Ireland consists of 

 glaciated rocks less or more weathered, or well preserved. The polished surfaces are 

 covered in low grounds with drift. Boulder-clay, unstratified, is next to the rock ; 

 sands and gravels and peat bogs are above the clay. The solid rocks have been greatly 

 worn away since the formation of the Antrim basalt; the drift since the Glacial 

 period. The hills and hollows in the rocks are the result of wearing and " denuda- 

 tion; " the debris is the "drift" partially re-arranged. 



This was shown by examples in, — 1st, Chalk and basalt in Antrim ; 2nd, Mountain- 

 limestone, etc., in Sligo; 3, older rocks about Valentia and the south-west; 4, granites 

 and metamorphic rocks in Donegal and the north-east. The effect of the Atlantic oq 

 cliffs at Slieve Liag in Donegal and elsewhere on the Irish coast was noticed. 



It was shown from these large coast-sections that the upper surface now has no 

 relation to the older contortion, fracture, and folding of these disturbed and faulted 

 rocks, which lie under newer and less crumpled beds, up to the peat. The probable 

 dimensions of the ice-engines which worked on the surface of Ireland was shown by 

 comparison of glaciers in Iceland, Norway, and elsewhere, with the Irish marks, 

 which indicate ice of equal size. Beginning with the smallest and rising to larger 

 systems, Irish marks indicate ice of equal dimensions, till horizontal grooves at 2000 

 feet above the sea indicate ice more than 2000 feet thick, moving over Ireland into the 

 Atlantic in a south-westerly direction. It was shown that the ice at its maximum 

 probably extended from the Polar Basin to Cape Clear. In support of this view, 

 boulders on Fairhead, and the denudation and glaciation of the central highlands of 

 Scotland, and of Scandinavia, Finland, and the United States, were shortly noticed. 

 The question whether these extensive tracts were made by glaciers or by icebergs was 

 discussed. The marks in Ireland and Scotland seem to the writer to indicate ice more 

 than 2000 feet thick moving along the bottom of lochs, straits, and shallow seas, in 

 water less than 1800 feet deep, with large local ice-systems upon high lands. It was 

 shown that glacier-ice aground in water is easier to push horizontally, and so to drive 

 over impediments in proportion to the weight lifted vertically by flotation. 



Rubbings from glaciated rocks placed beside shaded Ordnance maps of parts of 

 Scotland and England, showed that similar forms had been somehow produced on 

 scales of inches and miles upon the rock-surface of Scotland. 



The author's conclusion is as follows : — 



" Ireland has been greatly denuded. Glacial and marine action are the most 

 powerful known to me. Glaciers and the sea shaped Ireland, as I believe. Rivers 

 and weathering have done little to obliterate the tool-marks of ice and the sea since 

 the end of the last of a series of Glacial periods." 



Discussion. — Prof. Ramsay agreed in the main with the views of the author, and 

 with the opinion of Agassiz as to the great extension of cold at a certain period both 

 in the northern and southern hemispheres, though he could not carry the theory quite 

 80 far as to leave merely a narrow equatorial belt unaffected by ice. He had, how- 

 ever, never seen any mountain region in the northern hemisphere on which there 

 were no traces of glacial action. As to Ireland, he knew of no portion of its surface 

 which had not been glaciated, and the great striations actually extended, as they do 



