HAP. V.] DEVONIAN PERIOD. 53 



interior of Sutherland. But as if to make this point quite 

 certain, in the very heart of the county, the two solitary 

 conical mountains of Ben G-riam, 1,936 feet, which rise so 

 conspicuously above the worn platform of old crystalline 

 rocks, are cakes of conglomerate formed out of the detritus 

 of the schists on which they lie. . . . The same deposit 

 {i.e. Old Red conglomerate) runs southward from Suther- 

 land along the eastern coast of Ross and the shores of the 

 Moray Firth. It stretches up the valley of the Great Glen 

 and rises in Mealfourvonie to a height of 2,284 feet. 

 Thence it sweeps eastward along the seaboard of the coun- 

 ties of Inverness, Nairn, Elgin, Banff, and Aberdeen, and 

 detached portions are found thirty or forty miles in the 

 interior. . . . The highest of them is that which runs up 

 the valley of the River Avon above Toinintoul, where it 

 reaches a height of upwards of 1,300 feet above the sea. 

 The coarseness of the conglomerate at this locality is re- 

 markable ; huge blocks of the schists and other crystal- 

 line rocks of the district piled up in the conglomerate 

 there, bear emphatic witness to the abrasion of the High- 

 lands during, as well as before, the time of the Old Red 

 Sandstone." 



"Along the southern border of the Highlands the evi- 

 dence is less obtrusive, but perhaps no less definite. 

 From sea to sea the Highland mountains are there flanked 

 by the Old Red Sandstone in low rolling plains that creep 

 up to the base of the hills, but sometimes, as in the case 

 of the Braes of Doune, rising into long heathery heights, 

 that form a kind of outer rampart to the main mass of 

 the Highlands. Even from a distance the stratification of 

 the conglomerates and sandstones of these uplands can be 

 easily traced, the beds presenting their denuded truncated 

 -ends toward the mountains, to which they evidently at one 

 time were prolonged, and from, the waste of which they 

 were formed. If we prolong with the eye the lines of 



