598 



PHYSICAL GEOGRAPHY. 



same to the eye as in the heliotype. On walking over the mountain, one 

 can observe every stage of the process of decomposition. At first there 

 may be a ledge, with pieces slightly removed from it. Next, one will be 

 troubled to decide whether a series of fragments occupies the original 

 space of the ledge, so that the position of the strata can be accurately 

 determined, or whether the blocks have been removed out of place. In 

 other piles there will be no question that every trace of the original 

 stratigraphical structure has vanished. From these heaps there is an 

 unbroken series to the piles of angular gravel and sand, which have 

 resulted from continued decomposition. The extreme is where the sand 



Fig. 71. — ^VIEW ACROSS THE RAVINE SOUTH OF MT. ADAMS. 



Mt. Washington rises back of the debris. 



has allowed vegetation to grow, and to accumulate a mould fitted for the 

 development of the few hardy flowers and miniature trees of the alpine 

 district. 



The more common case of disintegration through frost may be seen 

 along the sides and at the bases of precipices. Several of our figures 



