Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/363

 on which this explanation proceeds, as it would lead into discussions foreign to the views of this paper, and as it is undoubtedly supported by a sufficient mass of evidence.

It is proper however before entering on this examination to recall to the reader the general disposition of the lines, and that of the vallies which they occupy. They are found commencing within a very short distance of that summit which is the common origin of the waters of the Spey and Roy, the one running to the east, the other to the west. In their progress westward they increase in number and in the perfection of their forms and markings, maintaining the same level throughout: while the bottom of the valley, now the course of the Roy, descends with a rapid declivity towards its junction with the Spean. One of these lines is found ascending the valley of the Spean for a few miles, and terminating in the great common valley of the Spean and Roy, at a point agreeing with that of its corresponding line which descends from the valley of the Roy. From Glen Roy the same lines are continued into Glen Turit, a valley opening into that of the Roy. Here they meet with its bottom as it rises during their level progress, but they are renewed in Glen Gloy, a valley placed in a reverse direction to Glen Turit, continuing throughout its descent in a course similar to that which they held in Glen Roy, until they disappear near its lower extremity and before its junction with the vale of the Lochy, the common exit of Glen Gloy and the conjoined vallies of the Roy and Spean.

We are now to examine the probable course of the torrent or deluge assumed to be the cause of these lines. It is most consonant to the present state of things to imagine that it flowed from east to west or from the source of the Roy towards its termination. If it be conceived to have flowed in the reverse direction from the