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XIII. 



A MAP TO SHOW THE DISTRIBUTION OF ESKERS IN IRELAND. 

 By PROFESSOR W. J. SOLLAS, LL.D., D.Sc, F.R.S. 



(Plate LXIX.) 



(communicated by permission op the dieector-geneeal of the geological survey.) 



[Eead FEBEUiET 20, 1895.] 



Introduction, Personal. 



In the summer of 1893, my friend Mr. Praeger and I left Dublin for Maryborough 

 to examine the remarkably fine esker which occurs near that town.* The 

 writings of Jukes had inspired us with the idea of the marine origin of eskers, 

 and we were persuaded that it only required careful search to discover traces 

 of marine organisms. We searched intently from early morning to late evening, 

 but without success; not a trace of a shell rewarded our efforts, and this, not- 

 withstanding the favourable character of much of the material composing the 

 esker, which, from its fineness and somewhat argillaceous nature, was well fitted 

 for the preservation of fossils, had these, at any time, been present. 



This result, being in general harmony with that obtained by other inves- 

 tigators, will probably not be considered surprising; nor were we so much 

 impressed by it, as by certain positive characters, which, although we had 

 frequently seen eskers before, we now seemed to perceive for the first time. 

 These were the definite form of the long narrow ridge, and, more particularly, 

 the steepness of its slopes, and the looseness of its material, which evidently 

 rested at an angle not far different from that of its angle of repose. 



This single instance was in itself sufficient to dissipate all notions of a marine 

 origin. We were already familiar with the fact that such ridges are nowhere 

 known to be in process of formation by the sea at the present day ; but we now 

 perceived that the fact of loose material resting at approximately its angle of 

 repose was incompatible with the idea of its deposition beneath the waters of a 

 sea by means of currents. 



The question that pressed itself for solution was this : — How could a ridge of 



* The northern part of this esker is shown within the southern border of PI. lxes., south of Mouat- 

 mellick. 



TKANS. EOT. DUB. SOC, N.S. VOL. V., PART XIII. 5 T 



