^14 MR MILXE OX THE PARALLEL ROADS OF LOCHABER. 



about three or four miles to the north of Loch Laggan. The accumulation is enor- 

 mous. Blocks are piled over each other, to such a height as to render the general 

 surface of the moor, over a wide extent, quite undistinguishable. This accumu- 

 lation occurs not at the mouth of any valley. On the contrary, the hills near these 

 lilocks on the east side, are not much furrowed even by mountain torrents, and 

 jiresent a somewhat steep and high wall face to the west. On looking round for 

 any possible explanation of the occurrence in this spot of so unusual a quantity 

 of boulders, consisting almost entirely of grey granites, whilst the rocks on which 

 they lie are different, 1 could not help noticing that the valley on the opposite or 

 west side presented an opening or depression, though at the distance of 2 miles. 

 This opening is the outlet of Loch Treig, and bearing about WSW. by compass. 

 The appearance of the locality at once suggested the probability that the blocks 

 had in some way issued through this opening, and had been transported across 

 the valley to their present situation, where their farther progress was arrested 

 by the lofty hiUs forming here the east side of Glen Spean. 



I have already stated reasons for thinking that no glacier issued from Loch 

 Treig. The only alternative seems to be the agency of water. 



I proceed now to shew that the lake theory of the Lochaber shelves, and the 

 principles on which I have endeavoured to account for the formation of lakes, and 

 the eventual depression and drainage of them, are not inconsistent with any esta- 

 blished geological truths, — but, on the contrary, receive support from collateral 

 considerations. 



1 . The first circumstance which I shall notice, is the occurrence of Parallel Roail.i 

 mother valleys similar to those of Lochaber, the formation of which caij'be attributed 

 to no other cause than lakes. 



I have the less hesitation in availing myself of this argument, when I find 

 Mr Dauwlx advertnig to traces of shelves at Kilfinnin, and in the valley of the 

 Spey, in support of his theory. 



But if Mr Darwin's views are sound, traces of shelves should not be confined 

 to the two localities just mentioned ; they should be visible in other parts of the 

 country of equal height as the Lochaber mountains. 



On the other hand, if it should appear that there are in many valleys, distinct 

 beach lines, all horizontal, and presenting no uniformity of height above the sea. 

 the argument against a sea theory will be strengthened, whilst a strong analogy 

 wdl arise to favour the lake theory, — if these beach lines, precisely similar in all 

 essential features to those of Lochaber, can, from their inland situation, and other 

 circumstances, be clearly shewn to have been produced by the waters of lakes. 



I proceed therefoi'e to mention a few localities out of many, where phenomena 

 similar to those of Glen Roy are observable. 



(1.) At Inverouman (about 40 miles SW. of Lochaber) there is a lake called 



