58 Mr Thomson on the Parallel Roads of Lochaber. 



ioY the consideration of those who may have it their power 

 to gain farther information on the subject. Should any mu- 

 tual action of a glacier and its moraine have occasioned the 

 peculiarity in question, we might expect to find some re- 

 mains of the moraine between the terminations of the upper 

 and those of the lower shelf. It may here be remarked, that 

 there is not the same- difficulty in accounting for the removal 

 of this moraine, as for that of the barriers supposed by Mr 

 Milne to have existed at the mouths of the other glens. For, 

 in this instance, the water from the lake of Glen Gluoy must 

 have dischai'ged itself over the top of the moraine ; while, in 

 the case of the other glens, it certainly flowed out by the sum- 

 mit-levels between the glens ; and would, therefore, have no 

 power of cutting away the barriers. 



There is, in the Lochaber district, still another glen, con- 

 taining a slielf, which was discovered by Mr Darwin, and de- 

 scribed by him in the Philosophical Transactions of the Royal 

 Society of London for 1839. This glen is situated near Kil- 

 linnan, at the north-eastern extremity of Loch Lochy. The 

 shelf in it is stated by Mr Darwin to be in every respect as 

 characteristic as any shelf in Glen Roy. He believes it to be 

 perfectly horizontal ; and, in connection with it, he discovered 

 a watei'-shed, similar in its nature to those which have been 

 already mentioned. Now, as this author remarks, in regard 

 to any explanation by means of earthy barriers, " the dis- 

 covery of the shelf at Kilfinnin increases every difficulty mani- 

 fold." Every additional glen containing a shelf, in fact, re- 

 quires us to assume the deposition of an additional barrier, 

 and the subsequent removal of this by causes which have left 

 the shelves undisturbed. To admit, at the mouth of even a 

 single glen, of a barrier of such a peculiar nature as would 

 enable it to stand for a long time, but at last to be swept 

 away, although no river flowed over it, seems difficult enough ; 

 but to imagine ^-hat numerous glens should chance to be 

 placed in such peculiar circumstances, appears to be quite 

 unnatural ; no sufficient and generally-acting cause being as- 

 signed for the repetition of the supposed phenomenon. On 

 the other hand, the existence of the shelf in question is ex- 

 actly what should have been expected, according to the gla- 



