168 PKOCEEPINGS OF THE GEOLOGICAL SOCLETT. [Feb. 26, 



and Sutherland, all pointing to the same conclusion, viz., that they 

 are due to the passage of ice down the glens. 



Another consideration that impresses me in favour of the theory 

 that land-ice has caused these appearances, and which was also 

 remarked by Forbes in Norway, arises from the fact that they be- 

 come more extensively and clearly developed as we leave the low flat 

 regions and approach the mountains. For instance, although there 

 is good evidence that the greater portion of England was submerged 

 during the Drift-period, yet it is only in the hilly tracts of Wales 

 and the lake -district that we hear much of the rocks being striated 

 and ice-worn ; and in Scotland, although no part of the rocky floor 

 of the country seems quite free from these markings, yet it is in the 

 Highlands that they become so striking and intensely marked. But 

 the instances I have mentioned above, being all purposely taken from 

 localities close upon the present shores of Scotland, in my opinion go 

 to prove that even in the low grounds this glacial erosion has radiated 

 from the interior ; and that not only in the mountain-glens has this 

 action been due to glaciers, but down to the present coast-line we 

 must still ascribe it to an agent moving off the land, and not to 

 sea-ice. 



The evidence required to distinguish glacier- action from the effects 

 of an icy debacle rushing down the glens, caused by the dislocation 

 of sheets of ice owing to earthquake-shocks or movements of eleva- 

 tion, is somewhat different from what I have brought forward in the 

 preceding paragraphs. Here we have ice moving off the land in the 

 same direction as a glacier, or nearly so ; but in the one case the 

 action would be transient, and in the other of vast duration. Now 

 I think the amount of rock which has been worn away, even at the 

 mouths of the sea-lochs of the W. Highlands, as at Loch 'Fyne and 

 at the Kyles of Bute, opposite the steamboat-quay at Colintrive, by 

 the glacial action, is far too great to be accounted for by the passage 

 of even a succession of such debacles. The rounded outlines of 

 the tough gneiss and syenite, which I there saw, denoted to my mind 

 the long- continued grinding action of ice slowly moving over them ; 

 for I think the rapid, hurried rush of a sludgy mass, even although 

 repeated, would not produce such finely rounded contours : neither 

 would the grooves and furrows be so persistent and rectilinear in their 

 direction ; for the ice being in broken masses, and accompanied with 

 water and melting snow, would have more freedom of movement than 

 the rigid mass of a huge glacier or ice -stream filling the valley ; and 

 in the lower open grounds, where there were no heights to confine 

 the torrent, the straight persistent direction of the scores is even 

 more striking than in the glens and gorges, and to my mind still % 

 more inexplicable by such a catastrophe or series of catastrophes. 

 At Ellon, for example, on the cast side of Aberdeenshire, there are no 

 hills exceeding 600 feet in height within ten miles, and none exceed- 

 ing 1000 feet within 20 miles ; yet the scores on the rocks exposed in 

 the railway- cuttings and quarries have a remarkably uniform direction, 

 and run across hill and dale with a perfect indifference to the minor 



