AND OBSERVATIONS. 



115 



to be connected with the great central mass, which 

 may be traced intersecting the Highlands, from the 

 north-east shoulder of Scotland, to the south-west- 

 ern Isles. On the route northward from Fort- Wil- 

 liam, portions of mica and clay slate still present 

 themselves, as far as Highbridge. Around Letter 

 Finlay, mica-slate is found passing into gneiss. 

 But the rock in general, is a mixture of granular 

 quartz and compact felspar, associated with granite, 

 and intersected by veins of that substance : the 

 quartz has a dark greenish colour, and the presence 

 of mica in some specimens, shews its transition in- 

 to granite. This continues to be the principal rock, 

 till we reach Loch-Oich ; where it assumes a singu- 

 lar character, that may be described as a sort of 

 granitic conglomerate, with angular and rounded 

 masses of felspar, in a base of greenish-coloured 

 quartz. Here, too, specimens are afforded of a gra- 

 nite, consisting chiefly of reddish crystallized fel- 

 spar. 



Fort-Augustus. — At Fort-Augustus, gneiss, 

 with a great variety of characters, shewing its trans- 

 ition into mica-slate, presents itself in abundance ; 

 and granite occurs to the north-east, 



Corryaraik. — Turning now towards the east, 

 we find a tract of primitive country, reaching to the 

 mountain of Corryaraik, and along the whole course 

 of the Spey. On Corryaraik, besides granite and 

 mica-slate, inclining to gneiss, we observe a fine 

 variety of syenite. 



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