196 



tlowever that may have been, it seems more than 

 probable, that in a familiar conversation on the pheno- 

 mena of nature, Louis may have meant to convey to 

 his son the idea, that by the changes of temperature 

 the operations of heat and cold, promoting a decompo- 

 sition of rocks ; and also by the operations of winds 

 and torrents of rain, which convey the debris into the 

 vallies ; the mountains would, at length, be reduced to 

 a level with them. Be this as it may, it is not essen- 

 tial to the subject in view. 



That almost every species of rock is liable to de- 

 composition, in a certain degree, is admitted. That 

 some are much more liable than others, is equally 

 certain. That some kinds are subject to an entire de- 

 composition, cannot be denied. But in order to deter- 

 mine the degree, or tendency of the several kinds of 

 rocks to decomposition, and the extent to which they 

 are liable ; and also, the degree of influence which 

 such a change may have had, in producing the won- 

 derful results, that are supposed by many to have 

 taken place, it is necessary to take a cursory view of 

 the several kinds most prevalent, and of which the 

 crust of our globe appears to be composed, in order 

 that we may be enabled to form some correct ideas of 

 the extent of this operation. 



Rocks, it is well known, are divided into the follow- 

 ing classes, viz. primitive, transition, secondary or 

 floetz, alluvial, and volcanick. These are again sub- 

 divided into their several kinds. The different kinds 

 of rocks arranged under the denomination of granite. 



