358 Mr Milne on the Parallel Boads of Lochaher. 



Gluoy, which, by no possibility, could bo accounted for by a moraine 

 at or near Moeldhu. 



That there are certain appearances in the valleys of Lochaber, 

 which must have been produced by attrition of some kind, I am free 

 to admit. Water, accompanied by gravel and other detritus, appears, 

 however, to have been the agent, and not ice. At the Monessie Falls, 

 the valley is compressed to a narrow gorge, and the rocks forming the 

 east side, present evident marks of attrition on a large scale, the rough 

 faces of the rock being all down the valley. The rocks are hero 

 covered by sand and gravel, which indicate the flowing of water and 

 of drift at that height, when these rocks were worn down. In like 

 manner, at the outlet of Loch Treig there are immense expanses of 

 rock, all smoothed and rounded on the sides facinor the SW. or WSW. 

 by compass,* These smoothed rock-faces prevail to a height of about 

 786 feet above the lake, and 1680 feet above the sea, above which 

 level they are no longer visible. There are many boulders lying on 

 these smoothed surfaces, all of rounded forms. That these boulders 

 have come from the west, is evident from the nature of them ; several 

 of a pink coloured felspar, having been traced by me to a dyke of 

 the same peculiar rock a few hundred yards to the west, from which 

 they had evidently been derived. Another circumstance proved this 

 still more strikingly. In one place, a few hundred feet above Loch 

 Treig, I observed a series of rocky knolls, in an east and west line. 

 The parts of these knolls which were smoothed and worn down were 

 uniformly to the west, whilst their rough facts were all to the east. It 

 was clear, on an inspection of these knolls, that they had been worn 

 down on their west sides ; and the smoothed sides were so close to the 

 knolls respectively to the west of them, that nothing except some fluid, 

 charged, it may have been, with drift, could have possibly reached 

 and acted on them. 



This last point was still more palpable in several places where there 

 were narrow smooth-sided troughs, more or less steep, on the sides of 

 hills. These troughs had apparently been natural fissures in the 

 rocks, which had been smoothed by the long-continued action of water, 

 for the notion that ice could have entered and rubbed them, was en- 

 tirely precluded by their narrowness, situation, direction, and other 

 circumstances. 



M. Agassiz, in the paper before alluded to, says that he will never 

 forget the impression he experienced " at the sight of the terraced 



* The general line or axis of the lake is north and south by compass, the upper 

 part being towards the south, so that the motion of a glacier down this valley 

 would have smoothed all the south faces of the rocks. It is also important to 

 remark, that, on the west side of the lake, the rocks facing the lake are, as com- 

 pared with those on the other side, exceedingly rough, shewing still more 

 clearly that the smothing agent had crossed the valley of Loch Treig, in a di- 

 rection not parallel with its longer axis, but obliquely to it. 



