
t 
_ Parr IL. Szcr. ii. § 1.] EROSION BY RAIN. — 343 





























































































































































































































Fig. 94.—HARTH-PILLARS LEFT BY THE WEATHERING OF MORAINE-STUFF, TYROL. 
tion, rise up one after another far out into the plains, which were 
once covered by a continuous sheet of the formations whereof these 
detached outliers are only fragments. 
As a consequence of this ifequality in the rate of waste 
depending on so many conditions, notably upon declivity, amount 
and heaviness of rain, lithological texture and composition, and 
geological structure, great varieties of contour are worked out 
upon the land. <A survey of this department of geological 
activity shows, indeed, that the unequal wasting by rain has in a 
large measure produced the details of relief on the present surface 
of the continents, those tracts where the destruction has been 
greatest forming hollows and valleys, others, where it has been less. 
rising into ridges and hills. Hven the minuter features of crag and 
pinnacle may be referred to a similar origin. (Book VIL) 
1 Barrois, Ann. Soc. Géol. du Nord, vi. p. 366. 
