28 Trof. H. Carvill Lewis — Comparative Studies in Glaciation. 



It only remains to add that nothing like the uppermost pink band of 

 Lincolnshire was seen either in Suffolk or Norfolk, all the quarries 

 exposing the horizon where it would occur exhibiting only whitish 

 chalk, passing down gradually into grey chalk. 



YI.— COMPAEATIVE STUDIES tTPOST THE GlACIATION OF NoETH AmEEICA, 



Geeat Beitain, and Ieeland. 



By Prop. H. Carvill Lewis, M.A., F.G-.S. 



(Abstract of a paper read at the Birmingham M eating of the British Association, 

 September, 1886.) 



OBSERYATIOJSrS extending over several years upon glacial phe- 

 nomena on both sides of the Atlantic had convinced the author 

 of the essential identity of these phenomena; and the object of this 

 paper was to show that the glacial deposits of Great Britain and 

 Ireland, like those of America, may be interpreted most satisfactorily 

 by considering them with reference to a series of great terminal 

 moraines which both define confluent lobes of ice and also often 

 mark the line separating the glaciated from the non-glaciated areas. 



The paper began with a sketch of recent investigations upon the 

 glaciation of North America, with special reference to the significance 

 of the terminal moraines discovered within the last few years. The 

 principal characters of these moraines were given, and a map was 

 exhibited showing the extent of the glaciated areas of North America, 

 the course of the interlobate and terminal moraines, and the direction 

 of striation and glacial movement. It was shown ttiat apart from the 

 great ice-sheet of North-eastern America, an immense lobe of ice 

 descended from Alaska to Vancouver's Island on the western side of 

 the Rocky Mountains, and that from various separate centres in the 

 Cascade, iSierra Nevada, and Rocky Mountains, there radiated smaller 

 local glaciers. 



The mountains encircling the depression of Hudson Bay seemed to 

 be the principal source of the glaciers which 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. 



Detuiled 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 sur- 

 rounded 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, northwards out of Loughs Swilly 

 and Foyle, and south-eastward out of Dundalk and Dublin Bays; 

 while to the south the ice-sheet abutted against the Mullaghareik, 

 Galty, and Wicklow mountains, or died out in the plains. 



