MACULE — Til 12 PARALLEL ROADS OF GLEN ROY. 



125 



between Glen Roy and Glen Gloy, rising between the two and dis- 

 charging its waters on both sides. It is important, Maccnlloch con- 

 tinues, to notice that although the opposite sides of Glen Turit are 

 very little dissimilar either in shape or composition, they do not 

 equally exhibit equal traces of the " roads." 



Glen Hoy itself opens by a wide mouth, varying from five to seven 

 miles, into the great valley which stretches from the northern to the 

 western sea ; the whole of this space is uneven and hilly. Applying 

 the spirit-level to a great many points, Macculloch found them inferior 

 to the lowest " road " of Glen Roy, with one or two exceptions. The 

 opening of Glen Gloy is narrow. By a comparison of heights, 

 Macculloch found that Loch Laggan to the east is depressed 369 feet 

 below Loch Spey, and 432 feet below the uppermost ''road" of Glen 

 Roy. Supposing therefore that the water stood at the highest eleva- 

 tion in Glen Roy in the present state of the earth " it would run into 

 the Spey not only by the channel of Loch Spey, but by that of Loch 

 Laggan also." Eor these singular roads, Macculloch offered (1817) 

 the ingenious solution that they had been formed by the waves, or 

 littoral action of standing water. "The absolute water-level," he 

 says, " which is found to exist between the corresponding lines both 

 in Glen Roy and in those valleys which communicate with it, admits 

 of a ready solution on the supposition that a lake once occupied this 

 set of valleys ; nor can it be explained on any other. As a free 

 communication in one direction at least still exists among them, it 

 would even now be easy to imagine the water replaced in the same 

 situation; the difficulty of confining it will be a subject for future 

 consideration. If, however, a lake be considered the cause, it is plain 

 that the lines in question were once the shores of the lake ; and it 

 equally follows that it had existed at three different elevations, and 

 that the relative depths of these three accumulations of water may be 

 measured by the relative vertical distances of these three lines from 

 the bottom of the valley. Thus the nature of the retaining obstacles 

 becomes more complicated, and adds materially to the difficulties." 



Having compared all the appearances of Glen Roy with those 

 which are found in existing lakes, and considered the probable changes 

 which the drainage of such lakes would effect on these containing- 

 valleys, he proceeds to point out the difficulties with which, even this 

 hypothesis is encumbered. 



" It has been Been," he says, " that considerable deficiencies may he 

 observed in the courses of the ' lines/ as well in Glen Kov itself as in 



