171 



The blockage of Glen Gluoy seems to have been unconnected with 

 that of the other glens. The author ascribes it to a glacier occupying 

 the site of Loch Lochy, and fed from the high mountain to the north. 

 Ho explains the occurrence of a lower shelf in Glen Gluoy, which 

 stops short of the mouth of the glen, by a reference to analonfous 

 phenomena observed by Professor Forbes in the Lac de Combal. 



The shelf in a glen near Kilfinnan observed by Mr Darwin, is 

 accounted for by the glacier supposed to have occupied the site of 

 Loch Lochy. 



Mr Milne objects, to the notion of a glacier descending from Ben- 

 Nevis, and crossing Glen Spean to block up Glen Roy, that the in- 

 equalities of the intervening ground are so great as to render the 

 existence of a glacier in this direction highly improbable, more espe- 

 cially as the ice had a comparatively easy outlet northward towards 

 Fort- William. 



The author, however, endeavours to shew, that, if we assume a 

 climate intermediate between that which produces the glaciers of the 

 Alps, and that which forms the glaciers of the arctic and antarctic 

 regions, there is no real difficulty in imagining the existence of a 

 great expanse of ice descending from Ben-Nevis, at a level consider- 

 ably higher than that of the intervening hills, as well as of the high- 

 est shelf in Glen Roy. 



That such a climate may very probably have existed, the author 

 considers as proved by the researches of Professor Forbes among 

 the CuchuUin Hills, the elevation of which is much less than that of 

 Ben-Nevis. 



There is, in the phenomena of the great erratic blocks of the Alps, 

 proof of the former prodigious horizontal extension of glaciers, 

 although, in the existing chmate of the Alps, the glaciers no longer 

 exhibit the same horizontal development. The author also referred 

 to the indications of glaciers found in many parts of Great Britain, 

 some of them in the L'ochaber district, to the occurrence of organic 

 remains of an arctic character, and to the marks of the supposed 

 action of icebergs, as supporting the view of the existence of a gla- 

 cial climate at some remote period. 



The diluvial theory of Sir G. S, Mackenzie was briefly examined, 

 and certain objections urged against it. 



The author also alluded to the objection urged by Mr Lyell to the 

 glacial theory, on the score of the changes of relative level on sea 



VOL. II. U 



