( (200 ) 



inarks of their origin. Local circumftance^ 

 alone can determine to which of the two 

 principles it is to be afcribed ; to difcover 

 ^?vhich we muit attentively examine whether 

 the places where thefe figured ftones are 

 found exhibit any indubitable figns of vol- 

 canization. Yet even thefe are frequently 

 not fufficient, as there are many hills and 

 mountains which owe their origin to both 

 the great agents of nature, fire and water j 

 in w^hich cafe it will be neceffary to re- 

 double our attention, and fix it on the fub- 

 ftances originating from each ; to deter- 

 mine, by the relations thefe have to the ba- 

 faltes, from which of the two the latter de- 

 rive their formation. By diligently em- 

 ploying thefe means, we fliall be certain, 

 without fear of error, to elucidate and ad- 

 vance the enquiries relative to baialtes, and 

 be enabled accurately to determine which 

 of them are to be afcribed to the adlion of 

 water, and which to that of fire. 



But here a fecond queftion occurs, not 

 lefs interefting than the firft, relative to the 



caufe 



