356 Mr Milne on the Parallel lloads of Lochaber. 



about 3 miles, there are two considerable lakes, one called the Lalce 

 of Corry, and the other called Benofllap, which appear, from tlio 

 accounts received of them, to be about 1200 to 1300 feet above the 

 sea. There are several also on the Black Mount, at about the same 

 hio'h level. 



o 



Before concluding what I have to say regarding the parallel 

 roads of Lochaber, I may briefly notice the theory, that the lakes 

 which filled them may have been confined by glaciers, or by the mo- 

 raines of glaciers. 



This was one of the districts which, in the opinion of Agassiz 

 and Buckland, aflPorded undeniable proofs of the existence of gla- 

 ciers. The former published a paper* on the subject, in which he 

 says : " When I visited the parallel roads of Glen Roy with Dr 

 Buckland, we were convinced that the glacial theory alone satisfies 

 all the exigencies of the phenomenon ; and as this locality is the 

 best known, I may limit myself to this example for the explanation 

 of all others." 



M. Agassiz, in the paper now alluded to, explains the grounds on 

 which his theory rests ; and it is accompanied by a plan of the locality. 



It appears to me, (1.) That the facts on which M. Agassiz rests 

 his theory are incorrect. (2.) That, assuming as true the facts stated 

 by him, they still afford no evidence that glaciers existed in the 

 Lochaber valleys. 



(1.) There are three main fjicts relied on by M. Agassiz. He 

 states. First, That in Glen Roy, and in that part of Glen Spean be- 

 tween Bridge of Roy and Loch Treig, there are 3 shelves visible ; Se- 

 condly, That these shelves all terminate on both sides of the valley 

 at or near the Bridge of Roy ; Third, That the bottom of Glen Spean, 

 in front of Loch Treig, is not only polished with that polish charac- 

 teristic of glaciers, but is, moreover, scratched transversely, — that is 

 to say, at right angles to the direction of the valley, by a cause which 

 evidently proceeded from Loch Treig. 



To explain these appearances, it is suggested, that "the supposi- 

 tion of a great glacier descending from Ben Nevis, and shutting up the 

 valley of the Spean, hy resting on Moeldhu, which is opposite, com- 

 bined with the influence of a placier from Loch Trei<r, and which 

 would bar the valley a second time at that height, would explain all 

 the facts.'' ^ 4f 



These facts, for an explanation of which this theory was invented, 

 appear to me not to have been accurately observed. In the first place, 

 the three shelves do not occupy, as M. Agassiz asserts, *' all the si- 

 nuosities of the lower part of Glen Spean, and of the whole of Glen 

 Roy." It is only the lowest of the three shelves which occurs in 

 Glen Spean, and in the lower part of Glen Roy. The two upper- 

 most shelves stop short of the mouth of Glen Roy by about 2 miles, 



^' Jameson's Edinburgh New Phil. Journal, vol. xxxiii. p. 236. 



