252 ON THE DESTRUCTION OF ROCKS. 



alike to air and water, protects from further waste, 

 that decomposed trap which would otherwise shortly 

 be hurried into the sea by the rains of this watery 

 climate. But here, that which might benefit may 

 also injure; as the rocks capable of producing fertile 

 soils when exposed, such as the limestones and traps, 

 are thus excluded from the reach of destructive but 

 useful agents, till the Jabour of man learns to co- 

 operate with the designs of nature. 



In all these operations, we trace the beneficent hand 

 of Nature, which, by an admirable counterpoise of 

 the causes of ruin, supplies from the higher lands 

 that which the daily operations of the rains are re- 

 moving from the lower. Wherever soil is removed, 

 it becomes thus replaced; and, if not from the higher 

 lands, it is renewed by means of the access which the 

 elements obtain to the rocks beneath, in consequence 

 of the removal of their protecting covering. Thus 

 also, where the destruction is greatest, the supply be- 

 comes proportionally rapid ; preserving that state of 

 perpetual youth which, under whatever changes, is 

 still present in all the works of Nature's hand. 



Thus far the processes of destruction, or the decom- 

 position and the disintegration of rocks, have been 

 considered under their simplest modes, and as they re- 

 late to the immediate effects which follow them, namely, 

 the demolition of the solid land, the formation of 

 soils, and the deposition of loose materials in new 

 situations. It remains to examine some peculiarities 

 in the process of decomposition, which are interesting 

 to the geologist in another point of view ; being re- 

 markable, partly from their singularity and the dif- 

 ficultyof explaining them, and partly from discovering 

 to us some peculiarities in the concretionary structure 

 of rocks, that would not otherwise be conjectured. 



