832 MR. J. E. KILEOE ON DIRECTIONS OF ICE-FLOW 



prepared in conjunction with Mr. G. H. Kinahan, and published in 

 1872, has furnished important aid in the preparation of the maps 

 accompanying this paper. Dr. Hull, in his ' Physical Geology of 

 Ireland,' has described the glaciation of the country in considerable 

 detail ; and on his map * indicates an axis of glacial movement, 

 coincident with a great central snowfield which sent its flows north- 

 ward and southward. This the author represents as stretching 

 north-eastward between the counties of Galway and Antrim ; and 

 it is satisfactory to be able to state that all the evidence brought to 

 light since the publication of his book in 1878 goes to establish 

 his conclusions beyond question, with some additional details to be 

 mentioned presently. 



It has been stated in the opening pages of this paper, that the 

 prevailing direction of one set of glacial striae in Ulster is northerly. 

 More exactly the striae trend IS", by W. in Antrim and Londonderry ; 

 jS'.W. over the highlands of Fermanagh ; and X.E., X., and jS". by W. 

 in Donegal, &c., all indicating a northerly ice-flow. South of the axis 

 of glaciation, the flow has unquestionably been south-easterly, over 

 the central plain of Ireland and towards the Irish Sea, even across 

 the Mourne Mountain. This group is well glaciated from the sea- 

 shore at Carlingford Lough up to 1200 feet, and probably above 

 it ; the Fermanagh hills up to 1000 feet, and those in Donegal to 

 1340. The Irish glacial system thus attained important proportions. 



South-easterly striae abound on the east coast of the county of Down, 

 and some bearing northward occur in Eathlin Island. It is there- 

 fore obvious that the central snow-field extended at least to the coast- 

 line of Antrim, perhaps beyond it towards the Scottish coast opposite. 

 And it would seem, judging from the directions of striae in Fer- 

 managh and Donegal, that a spur or projection from the central 

 snow-field extended westward to the head of Donegal Bay, across 

 Barnesmore HiU. 



Relative Ages. — It remains to consider the Irish and Scottish 

 systems of glaciation with reference to their relative ages. 



Unfortunately the comparative freshness of striae belonging to the 

 two sets when occui'ring in proximity has not received the special 

 attention which alone could invest this class of evidence with due 

 weight. For it will be remembered that until of late both sets were 

 believed to indicate but one general ice-movement, and therefore to 

 be practically contemporaneous. It is, however, reasonable to sup- 

 pose that a very considerable accumulation of snow and ice obtained 

 in the Irish area, during the period of intensest cold, while the 

 Scottish system was gathering maximum strength, and that an ice- 

 movement outward was concomitant with this accumulation. Such a 

 movement would obviously be northward in Ulster; and would 

 maintain this direction until the Scottish ice-sheet invaded this area, 

 to move westward uninterruptedly. Previously formed striae would 

 thus be to a large extent effaced and replaced by those bearing 

 westward. Some might remain, to indicate a more ancient date for 



* P. 211. 



