202 Proceedings of the Royal Irish Academy. 



Admirable examples of the boiilder-clays on land, stretching down into 

 the sea, are now visible on either side of a former extension of the von Post 

 Glacier (PL XIY., fig. 11). These bovilder-elays in Tempel Bay, under noble 

 cliff-faces of Carboniferous rock, have a remarkable sunilarity to those familiar 

 throughout central Ireland. They result from the deposition of the intra- 

 glacial moraine as the glacier melted away, and they show how very differently 

 various types of rock become abraded during the movement of the ice. The 

 blocks of grey Carboniferous limestone have been roimded, and have received 

 excellent striations. The sandstones show similar signs here and there, though 

 many remain angular, and break up iinder atmospheric weathering along joints 

 and bedding planes. The red granites, which are here probably derived from 

 an unseen Archaean source, are rounded, but show no striations. Pied shales 

 are frequent, in flaky fragments, rounded in part and sometimes striated. 

 They contribute, by their comminution in the ice, to a red clay wliich forms 

 the basis of the moraines. Flints from the Carboniferous beds remain, 

 however, completely angular. These features, as will be readily seen, are 

 precisely those of the boulder-clay south of Dublin. 



The recently deposited Ijoulder-clay of Tempel Bay weathers into small 

 spiky pinnacles and vertical cliffs, on the face of which the larger stones stand 

 out (PL XIV., fig. 12;. Some of the cliff-forms seem to result from frost-action 

 along shrinkage-joints ; others are the sides of kettle-holes, where the deposit 

 has sunk, when some buried and residual ice-mass has melted away. These 

 kettle-holes, now filled with water, are commonly associated with the 

 moraines left by retreating glaciers, and have lately been discussed by Pi. S. 

 Tarr' in examples where stagnating ice stiU remains. J. E. Kilroe^ has aptly 

 attributed certain lakelets in the glacial deposits of Ireland to the former 

 presence of residual ice-blocks; and Lough Doo and the associated pools 

 above Pomeroy, in the county of Tyrone, no doubt originated in the same 

 manner, among gravels melted out of a glacier of the ice-sheet type. 



The occurrence of faiiiy pure ice under a ground-moraine which lias been 

 thrust up over it is strikingly evident in Spitsbergen on Cora Island in 

 Ekman Bay. As this ice melts, sinking occurs locally in the boulder-clay, 

 and kettle-holes arise in it freely. These remain in places from which the 

 ice has alread}' vanished. The history of the mass of residual ice which now 

 covers the west flank of Cora Island has been traced out by De Geer' from 



1 "Some Phenomena of tlie Glacier Margins of the Takutat Bay Eegion, Alaska," Zeitschiift 

 fiir GletSL-herkunde, Bd. iii. (1908), p. 94, and " Yakutat Bay Region, Alaska," U. S. Geol. Surv., 

 Professional Paper 64 (1909), p. 63. 



'' Memoir on the Geology of the District around Londonderry, Geol. Surv. Ireland (1908), p. 60, 

 and ibid, around Belfast, 19U4, p. 99. 



' Guide de rexcursion au Spitzberg, XI' Congres Geol. internal. (1910), p. 16. 



