GLACIERS IN GREAT BRITAIN AND IRELAND, 135 



district of Carboniferous Limestone which extends to the 

 lower lake. On the western and southern sides of this 

 lake the mountains rise abruptly and attain at Carn Tual 

 an elevation of 3404 feet, and here the glacial phenomena 

 are as strongly pronounced as in any part of Wales and 

 Scotland. 



The Black Valley, one of the most wild and striking, 

 which stretches from the head of the lower lake to the 

 base of Macgillicuddy's Reeks, exhibits these appearances 

 in their most marked form. The surfaces of the rocks are 

 here worn into smooth oval bosses, lying with their major 

 axes in the direction of the valley, and extending several 

 hundred feet up the sides. These polished roches mouton- 

 nees, however, assume a singular appearance when traced 

 into the upper lake. They rise above the surface in the 

 form of small oval islands, lying parallel to each other, and, 

 though frequently clothed with luxuriant vegetation, are 

 generally smooth and bare. It is almost impossible to 

 give an idea of these ice-moulded bosses, protruding their 

 naked backs above the calm waters of the lake, bearing 

 some resemblance to a number of up-turned hulls of ships, 

 or to a shoal of whales swimming half out of the water. 



Nearly all the main valleys present similar appearances. 

 The rocks, wherever freshly exposed, are grooved and stri- 

 ated, as I had several opportunities of observing in the 

 course of a short tour. The picturesque valley of Grlen- 

 gariff is specially remarkable for the freshness of the ice- 

 groovings and scratches. Sir H. T. De la Beche* draws 

 special attention to them here, and observes that the 

 scoring and rounding of the bottom and sides of the 

 valley, together with the striations, are unsurpassed by any 

 similar examples in Ireland. These strise point W.S.W., 

 stretching along the valley till it is submerged in the sea 

 at Bantry Bay. 



* Geological Observer, p. 312. 



