Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/335

 segments on the faces of the hill, and appearing to be the remains of more regular terraces furrowed and destroyed by the mountain torrents. Although the two upper lines are to be traced at the salient angle opposite to Glen Turit, they are interrupted and obscure to the very top of the valley. It is important to remark that the glen here takes a turn, forming a considerable angle, the opening of Glen Turit being not far from the re-entering one. At the salient angle the lowermost line is first seen, as on the right side it first is found at the entrance of Glen Turit, into the wide opening of which it runs, together with the upper ones, for a very short space; the whole of them speedily disappearing on this side of that glen, while on the contrary side the upper one runs well marked until its course is suspended by the gradual rise of the bottom of the valley.

Having, at this part of Glen Roy arrived at the point where three lines on each side are visible, it is time to observe that there is a perfect correspondence of level between the opposite pairs wherever they are found. Numerous trials with the spirit level confirm the universality of this rule, and from this point of the glen downwards to its junction with Glen Spean, I did not observe that any one instance occurred of even the little anomalous curvatures which I have already mentioned as happening in the upper part of the valley. They are in many places entirely wanting, as the plan will show, and as will be mentioned hereafter, but where ever they are present they obey the law. It is to this circumstance they owe that aspect of parallelism from which they have derived a part of their name, but which evidently can be a parallelism only in the vertical plane. The varying slope of the hills prevents all