The Glacial Theory. 



135 



When we study the arrangement of erratic blocks in 

 certain valleys in Scotland, we feel inclined to imagine our- 

 selves in Switzerland, says the same writer. 



" These mounds or ramparts abut against the walls of the valleys, 

 frequently forming at the mouths of the valleys a series of concen- 

 tric 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 terminated 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 Kendal; and in 

 Ireland, those which traverse the road that skirts the base of Cuil- 

 cagh 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 distance ; 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 consider- 

 able size, that we find the most angular. Now, if we consider the 

 arrangement of the valleys, which proceed in all directions from the 

 most elevated chains, and all of which present the phenomena of 

 erratic blocks, and of more or less continuous moraines, we cannot 

 for a moment doubt, that the cause of this transport has extended 

 its effects by radiating from the interior of the elevated points of 

 the district towards the plains. This is a fact of capital importance, 

 for it proves that the phenomenon of transportation is to a certain 

 extent a local phenomenon, inasmuch as it is connected with the 

 neighbouring chains of mountains. Each great group of mountains 

 in Britain has thus its system of erratic blocks limited to the extre- 

 mities of its valleys. It is thus that Ben Lomond on the one hand, 

 and Ben Nevis on the other, have their system of blocks indepen- 

 dent of that of Ben Wyvis; Schihallien and the Grampians have 

 equally theirs, as also the Pentland Hills, the Cheviots between 

 Scotland and England, and the mountains of Cumberland and West- 

 moreland ; lastly, the mountains which rise above Belfast, those of 



