410 MR MILNE OX THE PARALLEL ROADS OF LOCHABER. 



composed of materials washed down from higher levels. The adjoining moun- 

 tains of the district afford ample evidence, that gravel as well as boulder-clay had 

 been, by some cause or other, brought and deposited over all this country, filling 

 the valleys to heights exceeding the highest of the Glen Roy shelves. Thus, on 

 the turnpike road between Tyndrum and Inverournan, near the summit level be- 

 tween the two valleys, which I estimated to be about 1030 feet above the sea, 

 there is great abundance of sand and gravel. On the Black Mount, about 4 miles 

 north of Inverournan, and at a height of 1300 feet above the sea, there is an im- 

 mense accumulation of gravel and boulders, particularly on the south side of the 

 summit. In the high ground north of Dalwhinnie. which I estimated at 1200 

 feet aliove the sea, there are great heaps of gravel, forming mounds and ridges. 

 These facts, taken in connection with the undoubted fact, that detrital matter has 

 been spread over the greater part of Scotland, to a height of at least 1500 feet 

 above the sea, pretty clearly indicate, that detrital matter not only may have 

 been, but actually was spread over the Lochaber district, and filled its several 

 valleys, to the height of at least the highest of the Glen Roy shelves, thus afford- 

 ing ample blockage for its lakes. 



I may mention that there are, in this part of the Highlands, several lakes 

 of small size, at very high levels, the existence of which renders the lake 

 theory of the Glen Roy shelves less improbable than to some it may appear. 

 Thus, at the well-known pass of Rest-and-be-Thankful, there is a small lake, 

 which is about 800 feet above the sea, and there are traces of its having 

 stood formerly from 40 to 50 feet higher. To the south and west of Loch Treig 

 about 3 miles, there are two considerable lakes, one called the Lake of Corry, and 

 the other called Benofflap, which appear, from the 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 high level. 



Before concluding what I have to say regarding the parallel roads of Locha- 

 ber, I may briefly notice the theory, that the lakes which filled them may have 

 been confined by glaciers, or by the moraines of glaciers. 



This was one of the districts which, in the opinion of Agassiz and Buck- 

 LAXD, afforded undeniable proofs of the existence of glaciers. The former pub- 

 lished 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 pa])er now alluded to, explains the grounds on which his 

 theory rests ; and it is accompanied Ijy a plan of the locality. 



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



* Ed. Phil. Journal, vol. xxxiii., p. 236. 



