164 Charles Maclaren, Esq., on Grooved and Striated Bocks 



moving mountains of ice are known to have reached to a 

 greater depth than this. 



If the grooves, sci'atches, and polishing, seen on our rocks, 

 were produced by ice, tliose in the deep valleys must be due 

 to the action of glaciers, which are found in the Alps to glide 

 downward at the rate of one or two feet per day, with gravel, 

 stones, and sand adhering to their bottom. In this case the 

 largest grooves should be on that side of prominent rocks 

 which is toward the head of the valley, and this, it will be 

 seen, holds true in Scotland. On the other hand, if the 

 scratches, grooves, and polishing, were caused by an irrup- 

 tion of the ocean from the west, it is evident that the direct 

 wave setting eastward would be vastly more powerful than 

 the indirect or return wave, produced by the supposed recoil 

 of the water from the hills, and setting westward. It fol- 

 lows, that in the vvest of Scotland, where the effect of both 

 waves must be best seen, the grooving and abrasion shouLl 

 be greatest on the west side, and least on the east side, of 

 exposed rocks. It will be found that the case is just the 

 reverse. 



Glaciers are rivers of ice, whicli have their source at a 

 higher level in the mountains, in what the Swiss call Mers 

 de Glace, or " Seas of Ice." To account for glaciers in the 

 valleys shortly to be noticed, we must suppose that Scotland, 

 at some former period, had a climate as cold as Labrador or 

 Greenland, and that a permanent envelope of ice and snow 

 covered all the higher region of the Grampians. There is 

 nothing extravagant in the magnitude assigned to this en- 

 velope, for Agassiz informs us, that among the numerous 

 mers de glace in the Alps, there are some 20 or 30 leagues* 

 (50 or 75 miles) square. Glaciers or efflux streams of ice 

 from this central mass would glide slowly downward through 

 the openings at the outskirts of the mountains, such as the 

 valleys of Loch Fine, Loch Long, Loch Etive, Locli Earn, 

 and others ; and if the hypothesis be correct, the sides and 



siz Eludes Sur les Glaciers, p. 22. 



