1 62 



PHYSIOGRAPHY. 



[chap. 



All rough points of rock in the path of a glacier are thus 

 rubbed down^ and projecting masses are smoothed to the 

 form of rounded bosses. The flat-domed hummocks of 

 rock produced in this way are termed sheep-backs or roches 

 vwiitoiinees (Fig. 42), since, if seen in the distance, they bear 



Fig. 42. — Roches Moutonnees Creek, Colorado (Hayden). 



some resemblance to a flock of sheep. Hence, the passage 

 of a glacier across a country gives rise to peculiar features 

 not produced by any other agent of denudation ; and, by 

 these peculiarities, we may tell, with certainty, that ice has 

 been at work in a district where there is, perhaps, not a 

 vestige of ice at the present day. Thus, in many of the 



