MACKIE — THE PABA.LLEL ROADtS OF GLEN ROY. 127 



junction of the Spey and the Truim takes place, it is not difficult to 

 conceive that it was worn down by the action of the waters of the Spey, 

 causing the drainage of the highest level in Glen Roy ; or else after 

 that drainage had taken place by the failure of some other barriers. 

 The flow of the Spey and the Roy would then follow the directions of 

 the intermediate ground, and the present courses of these rivers, as far 

 as they were then free, would be established. If we now turn to the 

 western side of Glen Roy, and examine the elevation and direction of 

 the ground at its junction with the vale of the Lochy, we shall see 

 that both Glen Roy and Glen Spean bear one common water-mark or 

 ' line,' and unite in one common wide valley before they join the vale 

 of the Lochy. The imaginary barrier must therefore be removed at 

 least to that part of this valley where the ' lines ' terminate, which 

 is to a point beyond Teindrish. . . . But the form of this ground and 

 the gradual dilation of the valley into that of the Lochy is such that 

 no barrier could have existed here without occupying the whole of the 

 present valley of the Lochy." Macculloch therefore proposes to re- 

 move this barrier to an indefinitely distant point towards the sea. 



" If . . . Glen Gloy was dammed by a barrier of its own, indepen- 

 dently of that which occupied . . . the common opening of Glen Roy 

 and Glen Spean, we multiply our difficulties without necessity. A 

 continuous lake must therefore be supposed to have existed among 

 the present valleys of the Roy, the Spean, the Gloy, and Loch Lochy, 

 independently of a portion of Strathspey." Macculloch then gives 

 a map of the quantity of water he presumes under these circum- 

 stances must have occupied the surrounding country, but the po- 

 sitions he assigns to the barriers, and the condition he depicts for the 

 country, are not entirely such as the glacier theory, hereafter to be 

 noticed, will require. A considerable portion of Glen Lochy must 

 therefore, lie thinks, have formed a part of this common lake, and al- 

 though he cannot determine its boundary in this direction, it must, 

 according to his views, have extended at least to the north of the 

 opening of Glen Gloy. But that valley opening into what would 

 have been the middle of this lake, and being constantly diminished 

 from the deposit of alluvial matter from the streams, while the per- 

 manence of the ' lines ' upon the hills shows that they have under- 

 gone no violent changes, Macculloch does not incline to put any bar- 

 rier there. If he attempts the great Caledonian valley, he gets en- 

 tangled in a series of similar difficulties ; in short, he does not find it 

 possible to " fix upon a point which shall satisfy the requisite eondi- 



