276 The Irish Nahifalist. ' November, 



these researches, and urgently call for further investigations of the Drift 

 deposits scattered throughout Ulster. 



The Chairman said they should return thanks to Madame Christen 

 and to the Belfast Naturalists' Field Club for their work. 



Mr. Lampi^ugh said they were mapping the drifts of the Belfast area. 

 Before he came north he had not studied the Proceedings of the Belfast 

 Naturalists' Field Club as much as he ought to have done. Some admir- 

 able collections had been registered by the Club. 



ON THE GEOLOGICAL STRUCTURE OF IRELAND. 



BY PROF. G. A. J. COI.E, F.G S. 



iProf. Cole pointed out the more prominent phases of the geological 

 history of Ireland, mainlj' as an explanation of the existing scenic 

 features of the country, and expressed the opinion that probably very 

 little remained in Ireland of the old Huronian continent, unless portions 

 of it had appeared again in the cores of Caledonian folds. The stratified 

 but metamorphosed Dalradians of the west might be Cambrian or 

 older. The gneiss of the ancient moorland between Omagh and Cooks- 

 town was, moreover, very possibly pre-Cambrian, The Silurian sea must 

 have covered all the Irish area ; and the subsequent Caledonian folding, 

 with its axis running north-east and south-west, marked out the first 

 distinct lines of the existing country. The arches became filled with 

 molten rock as they rose, and denudation had again and again exposed 

 in them a core of granite. To this folding we owed the guiding lines 

 of Donegal, Sligo, and Mayo; the axis of Newry ; and, above all, the 

 Leinster Chain. The granites weathered into round-backed moorlands ; 

 the schistose foothills gave rise to picturesque ridges and ravines upon 

 their flanks. In the Dublin area, between the foothills and the sea, 

 quartzites and slates, usually regarded as Cambrian, had added the pro- 

 minent features of Howth, Braj- Head, and the two Sugarloaves, to an 

 already diversified landscape. The Old Red Sandstone lakes spread 

 across the hollows of the Caledonian continent, to be succeeded by the 

 inflow of the Carboniferous sea. The Lower Carboniferous beach-deposits 

 were now found on the summits of west Irish mountains, and very little 

 of the countrj^ could have escaped submergence. The Hercynian folding 

 produced the second series of structural lines, assisted by the varying 

 resistance of the Old Red Sandstone and the Carboniferous limestone to 

 denudation. The great limestone plain itself was probably to be looked 

 on as a vast shallow synclinal of the same epoch, into which, in later 

 periods, the Caledonian and Hercynian ridges poured down their detritus. 

 The terrestrial conditions of the British Trias were continued into the 

 Irish area, but the surviving beds of this period all lay north of Dublin. 

 The Rhsetic sea penetrated as far west as the Caledonian hills of Lon- 

 donderry, and marine conditions continued during early Liassic times 

 An uplift then probably occurred, and the sea did not return till the 

 middle of the Cretaceous period. The " white limestone," which formed 

 Bo distinctive a feature of the Antrim coast, represented the English 



