462 



tions which it is impossible to suppose them to have attained by 

 any other means than transportation upon ice. Such blocks, if 

 they had fallen or rolled from above, must have crossed deep 

 hollows, and again bounded up steep slopes with such a nice 

 adjustment of impetus as to exhaust itself exactly at the very top, 

 leaving them perched, where perhaps a single step in advance 

 would have precipitated them on another journey into the glen 

 next below. But this position so far fi^m being a difficulty, is 

 but the natural position in which we should expect to find them, 

 if ice had been the transporting agent ; because, what are now 

 summits must have been then shoals, upon which ice would 

 gi-ound, and upon which, also, ice melting, they would drop their 

 burdens. 



I send with this very short notice, a copy of the paper to which 

 I have referred,* upon the geological structure of the line of hills 

 on which this Roche Moutonnee occurs. In it there is an eye 

 sketch, tolerably correct, taken from Loch Fyne, of the range of 

 hills between its waters and Loch Awe, and I have marked in red 

 ink the point where the smoothed surface occurs. On the succeed- 

 ing page of the same paper there is an ideal section of the same 

 range of hills, and on this I have likewise marked both the posi- 

 tion of the rock and of the massive blocks of stone alluded to in 

 this letter. 



Since I came to London, my attention has been drawn by Sir 

 Charles Lyell to a paper, in which he has described a similar 

 phenomena in the United States, and in which he accounts for it by 

 the same explanation. In that case, however, the fact of a Eoche 

 Moutonnee on the summit of a range of hills is accompanied by 

 other very peculiar phenomena of transpoi-ted boulders, which 

 corroborate in a manner not to be mistaken the conclusion thus 

 arrived at. The continuity and uniformity of direction taken by 

 the floating ice in that case, as evidenced by the lines of its deposit, 

 is a peculiarity which must have been due to local causes. But 

 if the facts of submergence and elevation to such an extent be 

 established anywhere, there is no difficulty in applying the same 

 explanation to other cases, which, however different in detail, 

 involve the same essential facts. 



* Quarterly Journal of the Geological Society for November 1853. 



