TEANSACTIONS OF SECTION C. 633 



■western side of the Rocky Mountains, and that from various separate centres in 

 the Cascade, Sierra Nevada, and Rocky Mountains there radiated smaller local 

 glaciers. 



The mountains encircling the depression of Hudson Bay seemed to he the prin- 

 cipal source of the glaciers, wbich became confluent to form the great ice-sheet. In 

 its advance this ice-sheet probably met and amalgamated with a number of already 

 existing local glacial systems, and it was suggested that there was no necessity for 

 assuming either an extraordinary thickness of ice at the pole or great and unequal 

 elevations and depressions of land. 



Detailed studies made by the author in Ireland, in 1885, had shown remarkably 

 similar glacial phenomena. 



The large ice-sheet which covered the greater part of Ireland was composed of 

 confluent glaciers, while distinct and local glacial systems occurred in the non- 

 glaciated area. The principal ice-sheet resembled that of America in having for its 

 centre a great inland depression surrounded by a rim of mountains. 



These appear to have given rise to the first glaciers, which, after uniting, 

 poured outwards in all directions. Great lobes from this ice-sheet flowed westward 

 out of the Shannon, and out of Galway, Clew, Sligo, and Donegal Bays, northward 

 out of Loughs Swilly and Foyle, and south-eastward out of Duudalk and Dublin 

 Bays ; while to the south the ice-sheet abutted against the Mullaghareirk, Galty, 

 and Wicklow Mountains, or died out in the plains. 



Whether it stopped among the mountains or in the lowlands, its edge was 

 approximately outlined by unusual accumulations of drift and boulders, representing 

 the terminal moraines. As in America, this outer moraine was least distinct in 

 the lowlands, and was often bordered by an outer fringe of drift several miles in 

 width. 



South of an east and west line extending from Tralee to Wexford is a non-glaciated 

 zone, free from drift. Several local systems of glaciers occur in the south of Ireland, 

 of which by far the most important is that radiating from the Killarney Moun- 

 tains, covering an area of 2,000 square miles, and entitled to be called a local ice- 

 sheet. Great glaciers from this Killarney ice-sheet flowed out of the fiord-like 

 parallel bays which indent the south-western coast of Ireland. At the same time 

 the Dingle Mountains, the Knockmealdown, and Comeragh Mountains, and those 

 of Wexford and Wicklow furnished small separate glaciers, each sharply defined 

 by its own moraine. 



No evidence of any great marine submergence was discovered, although the 

 author had explored the greater part of Ireland, and the eskers were held to be. 

 phenomena due to the melting of the ice and the circulation of subglacial waters. 

 The Irish ice-sheet seemed to have been joined at its north-eastern corner by ice 

 coming from Scotland across the North Channel. All the evidence collected 

 indicates that a mass of Scotch ice, reinforced by that of Ireland and England, 

 filled the Irish Sea, overriding the Isle of Man and Anglesey, and extending at 

 least as far south as Bray Head, south of Dublin. A map of the glaciation of 

 Ireland was exhibited, in which the observations of the Irish geologists and of the 

 author were combined, in which was shown the central sheet, the five local glacial 

 systems, all the known striae, and the probable lines of movement as indicated by 

 moraines, striae, and the transport of erratics. 



The glaciation of AVales was then considered. Wales was shown to have 

 supported three distinct and disconnected local systems of glaciers, while at the 

 same time its extreme northern border was touched by the great ice-lobe of the 

 Irish Sea. The most extensive local glaciers were those radiating from the Snowdon 

 and Arenig region ; while another set of glaciers radiated from the Plinlimmon 

 district and the mountains of Cardiganshire ; and a third system originated among 

 the Brecnockshire Beacons. The glaciers from each of these centres transported 

 purely local boulders, and formed well-defined terminal moraines. The northern 

 ice-lobe, bearing granite boulders from Scotland and shells and flints from the bed 

 of the Irish Sea, invaded the northern coast, but did not mingle with the Welsh 

 glaciers. It smothered Anglesey and part of Carnarvonshire on the one side, and 

 part of Flintshire on the other, and heaped up a terminal moraine on the outer 



