461 



upon one or two prominent faces within twenty or thirty feet of 

 the summit. Above this it may be observed sloping oft", as it 

 were, with diminished force, over successive ledges towards the top, 

 until it passes close behind the very highest point, leaving that 

 point itself apparently untouched. 



I need hardly say, that in this case glacier action is impossible. 

 Even if this hill had itself been the seat of the glacier, it could 

 only have been snow so near the summit. 



There is one explanation which immediately suggests itself to 

 the mind, and, however difficult it may be to realize the conditions 

 which it involves, it is the only one which it seems to me to be 

 possible to suggest. It is that this peak, when subject to that 

 grinding force, was a rocky islet just appearing above the surface 

 of a glacial sea, and that floating icebergs, drifting from the north- 

 eastward, were constantly grounding upon its sides. I may 

 observe, that this explanation would accord with the fact that the 

 surfaces displaying most strongly the effects of the abrading 

 action ai"e considerably below the summit ; because, as ice floats 

 deep in the water — not more than one-twelfth of its bulk being 

 above the line of flotation — the heaviest masses would always 

 ground upon such a rock at a distance from the top proportioned 

 to the steepness of its declivity, and none but the lighter pieces 

 would ever be drifted over the higher points. 



If this peak was ever, as I have supposed, a mere rock just 

 appearing above the level of the sea, it becomes of course neces- 

 sary to suppose that its altitude above the present level of the 

 ocean is due to subsequent elevation. But as the geological 

 structure of the range — the dip and inclination of its rocks — were 

 clearly the same when it was subject to these forces of a glacial 

 sea, it becomes necessary further to suppose that the required 

 elevation has been a general one, affecting the whole country of 

 which this range forms a part. But if this were so, and whether 

 the elevation was slow and continuous, or more rapid and effected 

 by (as it were) successive heaves, we should expect to find at 

 corresponding points evidences of the same action at lower and 

 lower stages. There is certainly one such evidence, viz., that on 

 some of the lower ridges which fall in successive steps to the 

 shores of Loch Fyne there are some very remarkable examples of 

 large blocks of granite perched upon the very summits, in posi- 



VOL. 111. 2 p 



