250 NATURAL SCIENCE [October 



I have described, and to the depth of twenty-five feet, without any 

 indication of peat. The boring passed through beds similar to those 

 of the ridge, but horizontal, and of closer grain. No boulders were 

 met with until the water-bearing stratum had been tapped, and then 

 some lame ones were encountered. 



O 



In the sand-hill group, the few openings I have seen showed 

 less of the stratified arrangement, with a greater number of rounded 

 pebbles, exemplifying, I think, the passage of the true esker into 

 the morainic mounds, much acted upon by denudation. 



Are we then to take it as a settled matter that the esker sea is 

 all a myth ? 



I hardly think so. Even Geikie admits the probability of an 

 epoch of depression, and mentions that " gravel beds with marine 

 shells have been traced in Ireland up to a height of 1'2'do feet on 

 Montpelier Hill." Again, how are we to account for the presence 

 of large blocks of the red porphyritic granite of western Galway on 

 the Slieve Bloom mountains? This granite, as Jukes remarks, "is 

 easily recognisable inasmuch as it contains hornblende instead of 

 mica, and has large crystals of pinkish felspar, and is therefore 

 porphyritic," How could these erratics be borne to their present 

 situation except on rafts of floating ice ? It is known that blocks 

 of stone will sometimes rise through the glacier to its surface. 

 But in such cases the erratics do not rise above the level of their 

 origin ; they merely describe a plane of less incline than the upper 

 surface of the glacier. It may be contended that the period of 

 depression did not synchronize with the formation of the eskers, 

 and if so, we have new difficulties to meet. It may be that the 

 eskers were not all formed at one time or in one way, and that 

 most of the theories apply to a certain extent, while no one theory 

 yet propounded, is comprehensive enough to cover all the ground, or 

 clear enough to explain all the circumstances. I have no intention 

 and no ambition to attempt a new solution. But I have frequently 

 been struck by what appears to me the marked resemblance between 

 some eskers and certain phenomena in progress round the shores of 

 Galway Bay. 



In his essay on " The Arenaceous Rocks of Ireland " (Proc. B. Soc. 

 Dublin, n.s., vol. v., p. 507, 1887), Kinahan describes a curious spit 

 of conglomerate at Lisbellaw, Co. Fermanagh, which he believes 

 to have been formed in Silurian times after the manner of the 

 Chesil Bank. " In Lyme Bay the flow tide current runs from the 

 westward of Portland Bill which acts as a groyne; Chesil Bank or 

 Beach becomes coarser and larger as it is followed east, till it forms a 

 massive heap of shingle to the west of the Bill ; but eastward of the 

 Bill, in Weymouth Bay, there are finer accumulations. In Silurian 

 times similar forces were at work in the neighbourhood of Lisbellaw." 



