VOLCANIC UOCKS, BASALT, AND TRAP. 45 



In unstratified crystalline rocks, wholly destitute of animal 

 or vegetable remains, we search in vain for those most ob- 

 vious evidences of contrivance, which commence with the 

 first traces of organic life, in strata of the transition period ; 

 the chief agencies which these rocks indicate, are those of 

 fire and water ; and yet even here we find proof of system 

 and intention, in the purpose which they have accompUshed, 

 of supplying and accumulating at the bottom of the water 

 the materials of stratified formations, which in after times, 

 were to be elevated into dry lands, in an ameliorated con- 

 dition of fertility. Still more decisive are the evidences of 

 design and method, which arise from the consideration of 

 the structure and composition of their crystalline mineral in- 

 gredients. In every particle of matter to which crystalhza- 

 tion has been applied, we recognise the action of those un- 

 deviating laws of polar forces, and chemical affinity, which 

 have given to all crystallized bodies a series of fixt definite 

 forms and definite compositions. Such universal preva- 

 lence of law, method, and order assuredly attests the agency 

 of some presiding and controlling mind. 



A farther argument, which will be more insisted on in 

 speaking on the subject of metallic veins, may be founded 

 on the dispensation whereby the primary and transition 

 rocks are made the principal repositories of many valuable 

 metals, which are of such peculiar and indispensable impor- 

 tance to mankind. 



CHAPTER V. 



Volcanic Rocks, Basalt, and Trap. 



In the state of tranquil equilibrium which our planet has 

 attained in the region we inhabit, we are apt to regard the 

 foundation of the solid earth, as an emblem of duration and 



