Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/333

 for a certain space; and as this rule is general, it is unnecessary either to describe the spots or to mark the exceptions, but the fact itself is important. They are often ploughed across or obliterated by torrents obviously recent; and they sometimes also terminate abruptly in more ancient torrents; but still the two upper ones continue generally traceable and commonly very well marked: for the rest I must again refer to the plan. From these appearances we can often ascertain the relative difference of age between the hollow or torrent and the line: and we can also in some cases distinguish that a part of one hollow is prior and a part posterior to it. It may be remarked generally that the lines are best marked on the straightest sides, or on those slopes which lie in a straight or a slightly curved plane, while they are most obscure where the most numerous sinuosities, torrents, irregularities, or rocky faces occur. Among the best marked are the two uppermost ones on the right hand above Glen Turit, one of those at the head of Glen Turit, and the three above Glen Fintec on the same side. About two miles below the head of lower Glen Roy, a semi-circular cory or hollow opens on the right, giving rise to a considerable stream and falling gradually into Glen Turit. The two upper lines (for as yet there are no more) enter it a little way and then disappear. On its opposite side, or that which adjoins to Glen Turit, appear three marks offering the only considerable anomaly in the whole course of these lines. The two uppermost, which on a superficial view seem to be the continuation of the two before described, will be found more distant from each other than these, and on applying the spirit level to them it is seen that the lowest is continuous with the upper one of Glen Roy, but that the highest is a supernumerary one, although of the same apparent dimension and form, and that it terminates