to the Parallel Roads of Lochaber. 41 



rier to dam up the water to the level of the lower shelf, and 

 that it has been subsequently washed away by the river flowing 

 over it." He then suggests that the space between the termi- 

 nations of the upper and lower shelves should be examined, 

 to ascertain if the remains of such a moraine exist. I made 

 this examination with considerable care, but could find no 

 such remnants. There is some detritus in the main glen op- 

 posite the mouth of Glen Fintec; but it has obvious reference 

 to the present drainage, and is in no way remarkable. The 

 whole of Glen Gluoy is indeed singularly free from detritus ; — 

 a peculiarity which I consider due to its form. It is narrow, 

 and the hills rise steep and high from the very margin of 

 the river, so that there is no space where detritus could rest ; 

 and it is thus swept away as soon as it is brought down. This 

 circumstance is also favourable to the rapid and complete 

 removal of such a moraine, or barrier, as Mr. Thomson sup- 

 poses may have once existed. The mouth of the glen is 

 equally free from detritus, or other indications of the existence 

 of earthy barriers in a former condition of things. 



" A glacier occupying the present site of Loch Lochy, and 

 receiving supplies from the neighbouring mountains, would 

 appear," Mr. Thomson says, " to afford a sufficient explana- 

 tion of the phaenomena observed in this glen." This was 

 probably written under the impression that Glen Fintec com- 

 municated with Loch Lochy, and that the mouth of Glen 

 Gluoy was in the way of a glacier advancing from that lake. 

 But this is not the case. A glacier having its origin among 

 the high mountains to the N.W. of Loch Lochy — the only 

 hills high enough to produce one — and advancing from Loch 

 Lochy, must make its way past Maucomer and Brecklech up 

 the valley of the Spean, for so only will the levels permit. 

 This direction is about perpendicular to that of Glen Gluoy ; 

 and it would be only a lateral branch or arm, parting from 

 the main body, that could penetrate that glen. The mouth 

 of the glen is narrow, and the hill sides rise steep and high; 

 a little way up there is a considerable bend before we reach, 

 at a mile's distance, the bosom or sinus in the hill side, where 

 the moraine is conceived to have existed in connexion with 

 the lower shelf. All this shows the improbability of a moraine 

 being deposited at this place; and that recourse may as well 

 be had to the masses of ice with which Glen Spean has been 

 supposed to be filled, from its chief source in the Ben Nevis 

 group. But it seems impossible that such masses of ice could 

 deposit a moraine in the situation required ; and it even ap- 

 pears doubtful whether sheets of ice would deposit moraines 

 at all. 



