110 P. Macnair 8f J. Reid- On the Old Red of Scotland, 



the Highland area to an altitude of four times its present highest 

 elevation. Of course we do not mean to say that the Highlands 

 have not suffered any denudation since its mantle of Old Bed Sand- 

 stone rocks was swept from it ; but what we do mean to maintain 

 is, that supposing the original mountain chain was as high as the 

 present Alps, still these deposits would have swept, over it and 

 united the so-called basins of Lake Orcadie and Lake Caledonia. 

 It is impossible to seriously consider the idea that these basins con- 

 tinued to sink pari passu with the deposition of their sediments, the 

 narrowness of the ridge separating them entirely precluding the 

 idea, as the bottom beds would be contorted and folded long before 

 the upper beds of the 20,000 feet of sediment were laid down, 

 whereas we do not find a break in the whole series. On the other 

 hand, it would be nigh impossible to exclude the sea from such 

 a sinking area and for such a length of time. As if to make their 

 original connection quite sure, outliers and fragments are found on 

 the ridge of crystalline rocks, as at Mealfourvonie to the height of 

 2,284 feet, at Toinintoul and Ehynie, right on what must have been 



the centre of the ridge, had separate basins existed, and where 

 there could have been no deposits. Sir A. Geikie 1 accounts for these 

 by supposing them to have been little isolated basins or arms of the 

 lake running into the separating ridge. But this method of 

 argument is exceedingly specious ; it would be much more scientific 

 to consider them as outliers of a great deposit that once covered the 

 Highlands, the remainder of which has now been entirely swept 

 away. Again, in Caithness there are many evidences of the 

 denudation of these basal conglomerates from the surface of the 

 old marine plain upon which they were laid down. In Ben 

 Gnam the conglomerates cap the top of a mountain 1,936 feet 

 above the sea-level ; the conglomerate is exceedingly coai - se, some- 

 times the boulders being two feet in length, the total depth of the 

 sandstone formation on this mountain being estimated by Geikie at 

 1,000 feet. Another instance is mentioned by Sir A. Geikie 2 in his 

 Memoir on the Old Red Sandstone of Western Europe, where he 

 says he was informed by Mr. Crawford, Tongue House, that on 

 Ben Armunin, a mountain rising to a height of 2,338 feet, in the 

 heart of Eastern Sutberlandshire, conglomerate occurs. There can 



1 " Scenery of Scotland,'' 2nd edition, p. 141. 



2 Trans. Roy. Soc. of Edinburgh, vol. xxviii, p. 3S3. 



