■J\ 



HUTTONIAN THEORY. 



109 



s 



} 



I 



CI 



V' 



I 



layers of the fame rock, which may perhaps have 

 rifeii to a great height above what is now the 



fur fa 



Indeed, fro 



n knowing the depth of 

 the gravel that covers the plain, and the average 

 quantity of the like gravel contained in a given 

 thicknefs of rock, one might eflimate how much 



of the latter has bee 



actually worn 



Wh 



d 



precife 



gh 



away 

 be found 



to give any weight to fuch a computat 

 be left for future inquiry to determine 



r 



a 



06. In thefe 



inftances, chalk and pudd 

 ftone, by containing in them parts infinitely 



deilriiclible than the 



fs 



general mafs, have, after 



they are worn away, left behind them very 



q 



al marks of thei 



ft 



Th 



fa 



me 



has happened in the cafe of mineral veins, where 

 the fubftances leaft fubjed to diflblution have 

 remained, and are fcattered at a great 



from their native 



r 



liable to decomDolition 



Th 



dill 



gold, the leaft 



very generally diffufed 

 is found, in a greater 



J 



of all the metals, is 



irough the earth, and 



or lefs abundance, in the 



fand of almoft all rivers. But the 



of th 



mineral is the folid rock 



and cavities contained in the rock, and from 

 thence it muft have made its way into the foil. 

 This, therefore, is another proof of the vaft ex- 

 tent to which the degradation of the land, and of 



the 



t Note xvii. 



4 w^ 



( 



\ 



