82 



The Irish Naturalist. 



September^ 



noticed that the erratics are found generally on the sea- 

 ward side of the hills and ridges, i.e. the west side. On 

 that side also the hollows are more filled with drift. 



All the exposed rocks and hummocks are rounded off 

 as by a gigantic plane. A promontory running out into 

 Lough Currane from Eight ercua to Rough Island, about 

 20 acres in extent and 126 feet high, easily accessible from 

 the Lake Road, shows ail the characteristics of ice action 

 on a large scale and in great detail. 



The strata being at a high angle, the edges of the layers 

 are exposed to the atmosphere, and are slightly weathered 

 so as to produce an appearance resembling striation but 

 due solely to rock structure. Where the strike does not 

 coincide with the striae, however, the glacial grooves are 

 sharp and distinct. They are seen best after rain. This 

 promontory is the very finest example of the result of ice 

 action that it is possible to imagine. 



The striation of the district is not in the direction that 

 one would at first sight expect it to be ; the general trend 

 of the valley is east and west, but the markings point 

 N.E. and S.W. as if the main current of ice came straight 

 across the lake, from Knockyline, the mountain mass 

 dominating the lake, and lying between the lake valley 

 and that of the Cummeragh River. 



Along the lake road, at the " Arbutus Rock," there is 

 a pocket of drift, containing striated boulders, etc. The 

 Arbutus Rock itself, a small outlying spur, shows, when 

 carefully examined, traces of cleavage planes at a small 

 angle to the bedding and the layers look as if they had 

 been forced over one another, producing slight terminal 

 curvature. 



All the exposed surfaces past this place are ice marked, 

 those at water-level more clearly than those by the road, 

 the water acting as a protection against weathering. In 

 places where the ice-motion was coincident with the strike 

 there is a slight difficulty in distinguishing the striae from 

 the upturned edges of the beds, but where the two directions 

 are divergent the markings are very distinct. The 

 direction of the striation in this area is parallel to that in 

 the promontory. 



