248 ON THE DESTRUCTION OF ROCKS. 



more active nature, which it is next my business to 

 consider. 



If in contemplating the towering peaks and the 

 solid precipices of an alpine region, braving the fury of 

 the elements and the floods of winter, the spectator is 

 at first impressed with the character of strength and 

 solidity which nature here seems to have conferred ori 

 her works, it requires b.ut a moment's reflection to 

 show, that every thing around him bears the marks of 

 ruin and decay. Here he learns to withhold his regret 

 at the perishable nature of all human labours, at the 

 fall of the strong tower and the solid pyramid, when 

 he sees that the most massive rocks, those mountains 

 which seem calculated for eternal duration, bear alike 

 the marks of vicissitude and the traces of ruin. Gra- 

 vity is here the great agent in those changes which 

 most forcibly arrest his attention ; changes by which 

 the solid precipices are shivered into atoms and hurried 

 into the valleys beneath. 



In these great revolutions however, other agents 

 must co-operate ; and the first here to be considered 

 is the power of frost. Expanding as it freezes, the 

 water which has entered the fissures, acts with irre- 

 sistible force, and detaches those enormous masses 

 which, in the seasons of winter and spring, daily fall 

 from the mountains. In Greenland, it is said that 

 these effects often take place with a noise emulating 

 thunder; but, if less conspicuous, they are sufficiently 

 common in all the alpine regions that are subject to 

 the extreme vicissitudes of heat and cold. 



It is to causes of this nature that the great ruin of 

 the sea cliffs is to be attributed, and not to the force 

 of the stones which the tide impels against their bases, 

 as has been sometimes asserted. No stronger proof 



