CHAP. xm. SUBMERGENCE OF SCOTLAND. 243 



of blocks of granite which have travelled from south to north 

 in Aberdeenshire, of which there would have been no ex 

 amples had the erratics been all brought by floating ice from 

 the arctic regions when Scotland was submerged. It is also 

 urged against the doctrine of attributing the general glacia- 

 tion to submergence, that the glacial grooves, instead of ra 

 diating as they do from a centre, would, if they had been due 

 to ice coming from the north, have been parallel to the 

 coast-line, to which they are now often almost at right 

 angles. The argument, moreover, which formerly had most 

 weight in favour of floating ice, namely, that it explained why 

 so many of the stones did not conform to the contour and 

 direction of the minor hills and valleys, is now brought 

 forward, and with no small effect, in favour of the doctrine 

 of continental ice on the Greenlandic scale, which, after 

 levelling up the lesser inequalities, would occasionally flow in 

 mighty ice-currents, in directions often at a high angle to 

 the smaller ridges and glens. 



The application to Scandinavia and Scotland of this theory 

 makes it necessary to reconsider the validity of the proofs 

 formerly relied on as establishing the submergence of a great 

 part of Scotland beneath the sea, at some period subsequent 

 to the commencement of the glacial period. In all cases 

 where marine shells overlie till, or rest on polished and 

 striated surfaces of rock, the evidence of the land having been 

 under water, and having been since upheaved, remains un 

 shaken ; but this proof alone rarely extends to heights ex 

 ceeding five hundred feet. In the basin of the Clyde we have 

 already seen that recent strata occur twenty-five feet above 

 the sea-level, with existing species of marine testacea, and with 

 buried canoes, and other works of art. At the higher level 

 of forty feet occurs the well-known raised beach of the western 

 coast, which, according to Mr. Jamieson, contains, near 

 Fort William and on Loch Fyne and elsewhere, an assem- 



E 2 



