6 



The Naturalist. 



cerned. It is loosened, and moves down the mountain side in greater 

 or smaller portions, and with a velocity proportioned to its position and 

 to the obstacles in its way. These obstacles, however, where they are 

 at all moveable, are caught u]) by it, and are hurried along to the foot 

 of the slope. Wherever that may be, the transported glacier will 

 almost certainly be placed in a lower temperature, and will melt, 

 depositing all the stones and earth collected in its passage. Even 

 before the eyes of Agassiz, huge mounds were thus formed ; and, if we 

 count upon the operation of the same agency for a great length of time, 

 the results, it may be imagined, must have been immense. The Swiss 

 knew these mounded depositions well, and called them moi'aifws. 



Besides the transporting action of the glacier, it has also an effect 

 upon the slopes which it passes over. It carries off 'some parts, and 

 levels others to a smooth shape, leaving the rocky masses untouched. 

 That many of our Scottish mountains especially, have undergone this 

 action, and that the lower grounds display the deposits, was discovered 

 by Agassiz, in company with Dr. Buckland, in 1840, while he was on 

 a visit to Great Britain. It was soon afterwards found that glacial 

 scratchings, remains of moraines, and blocks which had been carried by 

 ice were not confined to Scotland. Dr. Buckland recognised them 

 again and again in Wales and the north of England, where moraines 

 and erratic blocks are to be seen in all parts of the country. It is, 

 therefore, certain that in our island there must have been at one 

 time huge glaciers as large as those now found on the Alps. I 

 have referred to " glacial scratchings " for, besides levelling some parts 

 and rounding off others, the glacier often leaves stri^ or furrows in 

 its course, caused by the heavy bodies it has collected. These are 

 sometimes so marked upon very hard rocks as to give a striking idea 

 of the force of the originating movement. 



There are various other circumstances connected with glaciers worthy 

 of notice, but my object here has been simply to explain the great 

 theory which made xlgassiz so specially famous. In applying it to a 

 practical explanation of much that is to be seen on the face of the 

 globe, the transporting power of icebergs by sea must also be fully 

 taken into account. Nor can it be denied that there are many proofs 

 of the action of standing water, as in the case of the parallel roads of 

 Glenroy, and many others where level lines or beaches are observable. 

 But, though exposed in a detail here and there to some critical objec- 

 tions, the glacial theory of Agassiz was and is a noble contribution to 

 advancing science. It does not explain all, but it explains much ; 

 and, though observations on the transporting power of ice had been 



