Glaciers and Icebergs in Scotland. 



141 



so striking as to impress an observer with an idea that the 

 rocks must be different, though they are perfectly the same. 

 Probably both have undergone abrasion to some extent, but 

 one cannot help inferring that the abrasion has been ten 

 times greater in the one case than the other. What sort of 

 surface the hills beyond Loch Long exhibit, on close inspeC' 

 tion, I cannot tell, as I did not ascend any of them ; but I 

 travelled over a great part of the ridges A and B, and found 

 the exposed portions of the rock invariably smoothed and 

 rounded off, as if they had suffered abrasion. Now, a glacier 

 lodged within the valley would grind off the asperities of the 

 rocks at its bottom ; but what smoothed the very tops of the 

 ridges 1 Is it not probable that it was icebergs 1 When this 

 part of Scotland had an arctic climate, we may suppose the 

 group of hills extending from Loch Eck to Loch Katerine to 

 have formed a mer de glace, v*^here the ice, jammed into the 

 sinuosities of the valleys, would remain nearly immoveable, 

 and would have little abrading action. Here, consequently, 

 the rocks might retain their original roughness. But from the 

 outskirts of the group facing the low country, masses of ice 

 — icebergs — would be continually breaking off; and as they 

 moved eastward or southward, would rub and grind the sur- 

 face of the lower hills over which they passed. Here the 

 rocks would exhibit smooth surfaces and even or flowing out- 

 lines. This conjecture is not worth much, but the fact it 

 refers to merits notice. Finally, may not the terrace-like 

 marks previously noticed (at / ^ on the map) be the work of 

 icebergs, operating partly by cutting down the rock, partly 

 by shoving the loose fragments into hollows ? 



Pig. 3. 



ANCIENT BEACH. 



At numerous points along the shores of Gare Loch distinct 

 traces of an ancient beach present themselves. It consists 



