lOi Proceedings of the Royal Irish Academy. 



support this conclusion is derived from the fact that in the case of difilerent 

 glaciers moraine formation ceased at about the same date. Taking the Dunloe 

 and Killarney glaciers, for instance (see fig. 3), and counting inwards from 

 the point where they last coalesced, we find that in each case there were 

 three stages before the formation of moraines ceased altogether. The outer 

 moraines of the Killarney glacier are too indefinite to enable a similar 

 comparison to be made in tht case of the Caragh and Killarney glaciers. 

 The available facts are not inconsistent with the idea that moraine formation 

 ceased at the same date in the case of these two glaciers ; but beyond this it 

 is impossible to go. As regards the simultaneous cessation in the case of 

 tlie Dunloe and Killarney glaciers, an alternative explanation is forthcoming 

 in the fact that these glaciers were fed from the same reservoir in the Black 

 Valley, which in turn was supplied from the Kenmare basin to the south. 

 Once the Kenmare centre of accumulation failed to send ice north, over tlie 

 high watei'shed which separates it from the Black Valley, a rapid withering 

 of the Dunloe and Killarney glaciers became inevitable. Judging from the 

 height of the ridges (see fig. \), the svipply from tlie Kenmare centre into the 

 upper reaches of the Caragh lliver would be cut oft' about the same time as 

 that into the Black Valley, ur [>erhaps a little sooner. An appearance of 

 simultaneous rapid withering and consequent cessation of moi-aine formation 

 would thus be produced. 



As regards the ice-tongues of Lougii Guitane and the Flesk, which lie 

 further east, the evidence is not very clear, but suggests that they finally 

 withered away while the nioi-aine building of the Killarney glacier was still 

 in full progress. This is consistent with the idea that they must have been 

 cut ofl' from their source of supply in the Kenmare Valley at a relatively 

 early stage of the retreat. 



Tlie final retreat down the Kenmare Valley is free from this complication 

 of supply from an outside source which might lie cut off suddenly ; and it is 

 worthy of not* that no moraine barriers occur west of Kenmare (see Plate XV). 

 The retreating ice at this point cert-ainly ceased to form periodic moraines ; 

 and it is hard to find a cause for this cessation, unless, perhaps, the dwindling 

 size of the ice-remnant can lie regarded as supplying one. 



On the whole, however, the very definite termination of the period of 

 intermittent moraine building in the case of the glaciers which form the 

 subject of this paper would seem to Ije susceptible of explanation from local 

 causes. The question of the beginning of the period of moraine building is 

 even more obscure. The crescentic moraines on the northern plain have 

 certainly a definite outer limit ; but this appeai-s to be determined by the 

 coming on of the upland, or in the .case of the Caragh glacier by the sea. 



