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CHAP. XIII. 



On the Destruction of Rocks. 



IF the interest of geological facts bears any proportion 

 to their importance as they affect the condition of 

 organized beings, there is none in the whole range of 

 the science more calculated to attract attention than 

 that which relates to the destruction of rocks, to the 

 sure though tedious process by which they are con- 

 verted into earth and soil. On this process, depends 

 the very existence of all the races of terrestrial vege- 

 tables and animals. In the smallest fragment that 

 falls from the precipice, in the ceaseless flow of the 

 torrent and the river, in the summer's rain and the 

 frosts of winter, the Geologist contemplates the 

 agencies by which Nature renews and extends the 

 animated surface of the earth ; and, recurring to the 

 commencement of these actions, beholds it a dreary 

 waste of naked untenanted rock. 



Of the chemical Agents which tend to destroy Rocks. 



In enumerating the agents by which Nature operates 

 her important purposes of demolition and destruction, 

 if some shall appear insignificant in their power, or 

 tedious in their effects, there are others, of which the 

 results are rapid, important, and sensible to us where- 

 ever we turn our eyes. Even the agency of those 

 chemical causes which at first appears so feeble, is 

 often highly efficacious in preparing the way for the 



