270 THE ORY of the EAR T H. 



iron, or frozen water, fhould be found lodged in the cleft, we 

 might be enabled, from this appearance, to form a certain 

 judgment with regard to the nature of the power which had 

 been applied. This is the cafe with mineral veins. We find 

 them containing matter, which indicates a caufe ; and every in- 

 formation in this cafe is interefting to the theory. 



THE fubflances contained in mineral veins are precifely the 

 fame with thofe which, in the former part of this paper, we 

 have confidered as being made inftrumental in the confolidation 

 of ftrata ; and they are found in every fpecies of mixture and 

 concretion. 



BUT, befides this evidence for the exertion of extreme heat, 

 in that procefs by which thofe veins were filled, there is ano- 

 ther important obfervation to be gathered from the infpec"lion 

 of this fubjecl. There appears to have been a great mechani- 

 cal power employed in the filling of thefe veins, as well as that 

 necefTarily required in making the firft fraclure and divulfion. 



THIS appears from the order of the contents, or filling of 

 thefe veins, which is a thing often obferved to be various and 

 fucceflive. But what it is chiefly now in view to illuftrate, is that 

 immenfe force which is manifefled in the fradlure and difper- 

 fion of the folid contents which had formerly filled thofe veins. 

 Here we find fragments of rock and fpar floating in the body 

 of a vein filled with metallic fubftances j there, again, we fee 

 the various fragments of metallic mafles floating in the fparry 

 and filiceous contents. 



ONE thing is demonftrable from the infpe&ion of the veins 

 and their contents ; this is, the fucceflive irruptions of thofe 

 fluid fubflances breaking the folid bodies which they meet, and 

 floating thofe fragments of the broken bodies in the vein. It 

 is very common to fee three fucceflive feries of thofe opera- 

 tions ; and all this may be perceived in a fmall fragment of 

 flone, which a man of fcience may examine in his clofet, often 



better 



