102 Mr. Brycb on the Parallel Roads of Lochabcr. 



strueted by Messrs. W. and A. K. Johnston, under the direction of Sir 

 George M'Kenzie, Bart., David Milne, Esq., and Robert Chambers, Esq." 

 The same map accompanies a late paper on the Parallel Roads, by Sir 

 George M'Kenzie ; (Ed. N. Phil. Journ., vol. xliv. ;) it is that to which 

 Mr. Milne refers in his late important paper, (Ed. N. Phil. Journ., vol. 

 xliii. p. 339,) and on which the reasonings of Mr. James Thomson are 

 founded, an enlarged copy of it having been laid before the Royal Society 

 of Edinburgh along with his paper. 



Now, this map contains an important topographical error, calculated to 

 mislead those who may frame theories of the Roads without having made 

 a personal inspection of the ground. The error consists in this — that at its 

 junction with Glen Fintec, Glen Gluoy is laid down as opening towards 

 Loch Lochy ; whereas, in point of fact, the high ridge descending from the 

 table-land at the top of Glen Toorat, and shutting in Glen Gluoy on the 

 west, continues its course southwards fully a mile below the point where 

 Glen Fintec opens into Glen Gluoy. Glen Fintec is thus completely cut 

 off from direct connection icith Loch Lochy, the ridge in question being 

 continuous throughout, and rising to the height of from 1200 to 1800 feet 

 above the sea, or from 300 to 700 feet above the upper shelf. The rocks 

 of which the ridge consists are chiefly micaceous slate and quartzite, the 

 strata being nearly on end, and ranging in the direction of the ridge, or 

 about S.W. I could detect no traces of scratching or grooving, though 

 the rocks are laid bare in many places, and strew the surface in huge flat 

 masses. 



The error now pointed out involves another in the representation of a 

 portion of the upper shelf. The eastern portion is correctly represented 

 as terminating at the south-west comer of Glen Fintec ; but on the west 

 side, the shelf, instead of terminating as expressed on the map, is con- 

 tinued a considerable distance southwards of the opening of Glen Fintec ; 

 from half a mile to a mile, or perhaps more ; at first less distinct than usual, 

 then more plainly marked, tiU coming against a rocky projecting ledge on 

 the hill side, it fails as usual to impress it, and is seen no more. 



On referring lately to Sir T. D. Lauder's map accompanying his paper, 

 (Trans. Roy. Soc. Edinb. Vol. IX.,) which I had not looked into before 

 visiting the Parallel Roads, I found that his representation of this portion 

 of the district is much more correct. Glen Glouy is given in its true 

 dimensions ; and the stream formed by the union of the Gluoy and Fintec 

 waters is laid down as turning, at a place called Lowbridge, round the 

 southern termination of the mountainous ridge just described, and dis- 

 charging into Loch Lochy, nearly opposite to a village named Kyle-Rose 

 in Mr. Chambers' map. This representation is very near the trath ; but 

 perhaps too great extension is given to the southern part of Loch Lochy. 



IV. — Mb. Robert Chajsibebs' Tueort. 

 One of the principal objections which has been urged against Mr. 

 Milne's theory, is the absence from the district of a sufficient quantity of 



