14 MR. T. r. JAMIESON SFPPLEMENTAEY 



would check the rush of water and divert it. Future visitors 

 should devote some time to these interesting points ; and here I 

 would draw attention to what has been called the * delta ' of the 

 Rough Barn, a large mound situated where that stream joins the 

 Spean, and which was first noticed by Mr. Milne-Home. The top 

 of it is about 880 feet above the sea, and the level of the river at 

 its foot is 742 feet according to the Ordnance map, giving a 

 height of 138 feet for the so-called delta. An opening in its side 

 disclosed a deep mass of fine silty sand, the top of which I found to 

 be at a level of about 848 feet, but the upper part of the mound 

 above this appears to be composed of very coarse waterworn gravel 

 full of large boulders and blocks, some of them of great size, and it 

 is the rugged nature of the channel, arising from the tumbling down 

 of these large stones, that seems to have suggested the present name 

 of the stream. I have been unable to satisfy myself entirely as to 

 the origin of this upper portion of the mound. It is about 32 feet 

 deep, and if it is debris brought down by the supposed debacle, then 

 the lower portion must be of earlier date. It would also show that 

 there had been a lake or pool here before the above-mentioned 

 debacle occurred, and therefore that the Treig glacier must have 

 previously shrunk back from the mouth of the Rough Burn. 

 These are questions that would require careful examination upon 

 the spot, and I would commend them to the notice of future visitors. 



Thanks to the exertions of Mr. Milne-Home, who has done so 

 much in connexion with the Glen Boy problem, the Ordnance 

 Surveyors were induced to lay down upon their map, on the scale 

 of six inches to the mile, some of the principal lines of moraine 

 left by the Treig glacier when it extended across Glen Spean. 

 These will be found upon Sheet ISTo. 142 of the six-inch map of 

 Inverness-shire, and a reduced copy is given in one of Mr. Milne- 

 Home's memoirs.^ The mapping of the Survey quite bears out what 

 I said regarding the extent and range of these moraines, which are 

 probably the finest display of the kind in the kingdom. 



It is clear that during the time of the lowest Parallel Boad the 

 Treig glacier had retreated as far as the mouth of Loch Treig, 

 because that parallel is well marked on Tom-na-fersit, across the 

 entrance to the lake. As to whether it can be traced round Loch 

 Treig there has been some difference of opinion. Mr. Milne-Home 

 says that it can be so traced. Mr. Jolly, who knows the ground 

 perhaps better than any one, and has examined it from many points 

 of view, says decidedly that it cannot.^ The Ordnance map does 

 not show it, and I certainly could not satisfy myself of its exist- 

 ence anywhere beyond the entrance to the lake, although Loch Treig 

 seems to have sunk a little by the gradual wearing down of its 

 outlet. My impression certainly is that at the time of the lowest 

 line the front of the Treig glacier lay near the present outlet of the 

 lake. The moraines of the Allt-nam-Bruach were probably formed 

 by the left flank of the Corry Laire glacier, which must have 



1 Trans. Roy. Soc. Edin. vol.xxvii. (1876) pi. xliii. 

 ^ Trans. Geol. Soc. Glasgow, vol. Tiii. (1885) p. 89. 



