262 



ILLUSTRATIONS OF THE 



fo full of calcareous fpar, or of zeolite, that they 



)rous to fuch a degree, if the 



would become 

 cavities filled v 



P 



th 



latter fublt 



were 



F 



rapty, that they could hardly fuftain their 

 weight, and -much lefs that of the great mafles 



of rock incumbent 



In fuch cafes 



f 



that the cryflallized fubilances were part 



g 



pofition of the rock 



The 



truth is, that the infiltration of the water is a mere 

 gratuitous affumption, introduced for the pur- 

 pofe of explaining the exiftence of carbonated 

 lime in a (lone which had endured the adion of 

 intenfe heat ; and this afi'umption ought of 

 courfe to be rejected, if the phenomenon can be 

 explained by a theory, that is in other refpedls 



■- 



conformable to nature. The fpar, then, may 

 be confidered as a proof, that the rocks in que- 

 ftion are to be numbered with thofe unerupted 

 lavas which have flowed deep in the bowels of 

 the earth, and under a great comprefiiing force. 

 This is the more probable, that the Euganean 

 Hills, like fome whinllone hills in our own coun- 

 try, have, in certain places, a covering of flaty 

 and calcareous (Irata incumbent on them, even 

 at their fummits ^, fo that the torrent of melted 

 Hone, of which they are admitted to confiff, can- 



iiot have flowed from the mouth of a volcano. I do 



not 



f Phil. Tranf. 1775, p. 34 



-J 



