Cuchullin Hills in Skye. 91 



pelled to admit, (whatever geological causes, now unsus- 

 pecte(}, may hereafter be discovered,) must now be unhesi- 

 tatingly ascribed to the action of moving ice, rather than to 

 any other kind of agency with which we are acquainted. The 

 peculiar combination of circumstances in the Cuchullin Hills 

 renders this (it seems to me) more a matter of demonstra- 

 tion than can readily occur elsewhere. 



On visiting Coruisk this year by water, I had scarcely 

 landed on the rocks at the head of Scavig Bay, before I was 

 struck by the identity of their forms with the familiar ones 

 of the " Roches moutonnees" of the Alps ; and a closer exa- 

 mination proved the complete identity of the phenomenon 

 which has been so often described, and so well figured in 

 Agassiz's atlas, as to render details unnecessary, except to 

 specify the particulars in which the identity was actually 

 observed. Briefly, then, the rocks at the issue of the valley 

 of Coruisk, towards the sea, present — 



1. Invariably swelling surfaces of exquisite continuity of 

 form in a direction transverse to the length of the valley, 

 such as the ideal figure (Plate V., Fig. 4.) may rudely re- 

 present. 



2. In a direction parallel to the length of the valley, the 

 rocks are equally smoothed and shaven in their forms where- 

 ever their prominent parts are presented towards the head 

 of the valley ; but towards the sea they are often abruptly 

 terminated by craggy surfaces, shewing the usual rugged- 

 ness of the natural fracture of the hypersthene rock (in 

 which all the phenomena which we are now speaking of 

 occur), and exhibiting the phenomenon of stoss seite and lee 

 seite, so often described in the Scandinavian rocks. — (See 

 Plate v., Fig. 5. 



3. The forms of the smoothed surfaces are not commonly 

 spherical or dome-shaped, but elongated parallel to the length 

 of the valley, sometimes like portions of ellipsoids, some- 

 times like cylinders. 



4. The surfaces in question are quite like surfaces ground 

 down by art. They possess no polish (which the nature of 

 the rock hardly admits of), but they have a flatness truly 

 astonishing. The varying hardness of the mineral compon- 



