Dr. Mac Cul loch on the Parallel Roads of Glen Roy. 877 



difficulties without any necessity. A continuous lake must therefore 

 be supposed to have existed among the present vallies of the Roy, 

 the Spean, the Gloy, and Loch Lochy, independently of that portion 

 of Strathspey which I have described above. This last connection 

 we may for the present neglect, as well as those collateral bays or 

 masses of water connected with the principal lake, which if restored, 

 would also now flow to the sea. I have however so far conjectured 

 their extent, by a glance over the surrounding country, as to have 

 ventured on a map of them, so as to give a notion of the probable 

 quantity and extent of water which must, under these supposed 

 circumstances, have occupied this part of the country.* % 



A considerable portion of Glen Lochy must therefore have formed 

 a part of this common lake, and although we may not be able to 

 determine its boundary in this direction, it must have extended at 

 least to the north of the opening of Glen Gloy. But that valley 

 opens nearly opposite to the middle of the present lake. Exa- 

 mining therefore its condition, we find that it is diminishing, in 

 consequence of the increase of alluvial matter from the wasting action 

 of the surrounding streams. As the same action of these streams 

 must have produced the same effects in distant times, and as the 

 permanence of the lines proves that the hills themselves have under- 

 gone no violent changes, the ground that includes Loch Lochy 

 must always have been in a state of increase, not of waste, and the 

 barrier to the north, is consequently beyond the limits of this lake. 

 If now, we proceed northward through the great Caledonian valley, 

 and attempt to discover the place of this supposed barrier, we get en- 

 tangled in a series of similar difficulties, nor is it possible to fix on 



* Vide PI. 19. 

 + The coloured map will explain both this circumstance and the various directions 

 in which water raised to the upper line of Glen Roy would now flow to the sea. The 

 necessary distinction will be easily made by attending to the description. 



