in Scotland and Parts of England. 281 



and deep spaces which exist between the principal masses of 

 certain formations and their outliers, has always appeared to 

 me a violent supposition, and one with which we could not 

 rest. When, surveying the Old Red Sandstone district of 

 Sutherland and Ross shires, I found the enormous relics of 

 that formation, and the vast spaces left between them, marked 

 with the traces of an agent possessed of much higher mecha- 

 nical force, I felt how much more satisfactory it would be to re- 

 gard that as the great denudator, though certainly not to the 

 exclusion of water, the wearing force of which is everywhere 

 conspicuous within its own limits. To the south of Lake 

 Wenern, in Sweden, there is a series of hills, of about 700 feet 

 high, composed of horizontal transition strata, and the gneiss 

 surfaces between are all polished.* This is a case perfectly 

 parallel to that of the Ross-shire mountains, and doubtless 

 many other instances might be found. Valleys are generally 

 formed in the lines of ancient breaks or faults. Such is the 

 case with the valleys of the Lake Country. But as Mr Hop- 

 kins remarks — " The inspection of a model in which heights 

 and distances are on the same scale, must make it apparent 

 that the actual widths of the valleys in question could not 

 possibly be derived from the fractures in which we may con- 

 ceive them to have originated."! It is equally evident that 

 after certain longitudinal and descending hollows had been 

 formed by fracture, these, becoming the seats of moving ice, 

 would in time be widened to the extent which we now behold. 



* Bohtlink; Edin. New Phil. Jour., Oct. 1841. 

 t Quar. Jour. Geol. Society, iv., 86. 



