378 Dr. Mac Culloch on the Parallel Roads of Glen Roy. 



a point which shall satisfy the requisite conditions. It is not at 

 present necessary to pursue it further in this direction ; we must 

 turn our attention to the lower end of Loch Lochy. Here we find 

 the lake terminating in a wide alluvial plain, the recent increase of 

 w T hich is marked by the depth of peat on its surface ; while it com- 

 municates by wide openings, as well with the sea at Fort William, 

 as with the wide and open valley in which the western branch of 

 Loch Eil lies. If any probable place can be selected for the bar- 

 rier to the sea in this direction, it is at the narrowest part of this 

 opening, which lies at Fort William, between the skirts of the range 

 below Ben Nevis and the opposite hills of Ard Gowar. The aspect 

 of the ground, the course of the waters, and the nature and dispo- 

 sition of the rocks, render it difficult to assign any barrier nearer to 

 the opening of Glen Spean. But I have shown that there is another 

 free opening to the sea, from the supposed lake of Glen Roy through 

 Loch Shiel, and Loch Moidart. Another barrier must therefore be 

 interposed in this direction ; and thus there will be formed a large 

 lake occupying Glen Roy to some point beyond the present source 

 of the Spey ; Glen Spean, with the whole of Loch Laggan, and 

 Glen Gloy ; the Great Caledonian Valley, from a point, of which I 

 do not pretend to define the northern limit, to Fort William; Loch 

 Arkeig, and a part of the valley which includes it ; and finally the 

 western valley of Loch Eil, to some undefinable point lying towards 

 Loch Moidart and the western sea. The whole of this limit is 

 indeed not demonstrable, but I consider that the similarity, if not 

 the actual community of the lines of Glen Roy and Glen Gloy, 

 does demonstrate that a portion or the whole of Loch Lochy was 

 included in it. Here therefore a serious difficulty arises, although 

 perhaps not greater than that which is afforded by the view of Glen 

 Spean. This is the total absence of all corresponding water marks 



