1851.] HOPKINS — ERRATIC BLOCKS OF THE S. HIGHLANDS. 



21 



a very light-coloured granite, containing comparatively large crystals 

 of felspar. These characters I found so distinctly marked as to in- 

 dicate the great probability of these two classes of blocks being 

 derived from different sources. They appeared to have come down 

 the valley which forms the prolongation of that in which Loch Long 



Map of a part of the South Highlands, showing the granitic nuclei 

 of Ben Cruachan andBenNime, and the dispersion of the Erratic 

 Blocks from these Centres respectively . 



Scale of English Miles. 



Granite districts. 



'■■''yCo^y^i--: Erratic granite blocks. 



is situated, running for three or four miles N. and S. parallel to the 

 west shore of Loch Lomond, from which it is distant about two or 

 three miles. It then turns towards the N.W., and rises rapidly to 

 nearly the elevation of the ridge which separates its southern part 

 from Loch Lomond. As we approached this upper extremity of the 

 valley, the dark-grey blocks increased in number and magnitude ; 



