2S9I Professor Agassiz on the Glacial Theory, 



the arrangement of erratic blocks of certain valleys in Scot- 

 land, we feel inclined to imagine ourselves in a valley of the 

 Swiss Alps. I shall never forget the impression I experienced 

 at the sight of the terraced mounds of blocks which occur at 

 the mouth of the valley of Loch Treig, where it joins Glen 

 Spean ; it seemed to me as if I were looking at the nume- 

 rous moraines of the neighbourhood of Tines, in the valley of 

 Chamounix. These mounds or ramparts abut against the walls 

 of the valleys, frequently forming at the mouths of the val- 

 leys a series of concentric belts, which occur precisely at 

 those places where, supposing that the valley had at one 

 period been occupied by a glacier, it ought to have termi- 

 nated by the terminal moraines pushing against one another. 

 Similar mounds are observed at the mouth of nearly all the 

 valleys of mountainous countries. The most remarkable in the 

 British islands are, in Scotland, those of the banks of Loch 

 Awe and of Loch Etive, especially in the vicinity of Bunaw 

 ferry ; in England, those of the environs of Penrith and Ken- 

 dal ; and in Ireland, those which traverse the road that skirts 

 the base of Cuilcagh to the west of Florence Court. The 

 latter are more distinct than any that I have seen in the 

 United Kingdom. The nature of the blocks composing these 

 moraines, proves that they have not come from a great dis- 

 tance ; but that they have been detached from the upper part 

 of the valley, and transported by some cause to its extremity. 

 It is among these blocks, sometimes of very considerable size, 

 that we find the most angular. Now, if we consider the ar- 

 rangement of the valleys, which proceed in all directions from 

 the most elevated chains, and all of which present the pheno- 

 mena of erratic blocks, and of more or less continuous mo- 

 raines, we cannot for a moment doubt, that the cause of this 

 transport has extended its effects by radiating from the inte- 

 rior of the elevated points of the district towards the plains. 

 This is a fact of capital importance, for it proves that the phe- 

 nomenon of transportation is to a certain extent a local phe- 

 nomenon, inasmuch as it is connected with the neighbouring 

 chains of mountains. Each great group of mountain s in Britain 

 has thus its system of erratic blocks limited to the extremi- 

 ties of its valleys. It is thus that Ben Lomond on the one 



