246 



of the Catar 



although totally different in appearance, is evidently a mere modifi- 

 cation of the same substance in its most crystalline state, which has 

 received the name of primitive, and which alters in its aspect so 

 wonderfully as it passes through all its stages into chalk. 



If we then admit a posterior formation of granite and its family, 

 •we have only attentively to mark the difference between it and those 

 rocks which so closely resemble it in the volcanic regions, to estab- 

 lish the limit between them, and this, no doubt, in the advanced state 

 •of the science, will soon be discovered. 



I have as yet seen, even in the boulders so extensively spread 

 over Canada, very little appearance of a true granite, and am much 

 inclined to think, that the rocks in situ of that family are there new- 

 «er than is generally imagined, and to believe also that they have 

 heen not much disturbed by volcanic agency, but as this article has 

 already reached beyond the bounds, 1 should assign to it, I shall 

 merely at present observe, that I think the opinion that volcanic 

 agency is carried on, not in the granite, but very far below it, has 

 not been sufficiently attended to, and that in the case of the trachy- 

 tic and trap rocks with all other varieties of protruded and overlying 

 unconformable masses of admitted igneous origin, most frequently 

 the substances came from beneath the granite altogether, and that it 

 has not, except in the upheaving, been so much altered by them as 

 is supposed. If therefore there are enormous stores of amphibole 

 and pyroxene above those vast laboratories under the granite, and 

 if the materials from which the granite itself has been created % 

 •exist in an independent state, it is easy to suppose that the endless 

 varieties of interminglement and apparent confusion in the igneous 

 jrocks, may be accounted for, and that the crystallizations of pyrox- 

 ene, feldspar, amphibole, mica, leucite, &c. in the petro-siliceous 

 "basalt, may be simply accounted for by chemical arrangement, and 

 'the cooling of the lava, and the reason of the difference of bases 

 between those kinds of lava distinguished by Dolomieu as argilla- 

 ceous, siliceous, granitic or rather feldspathose and leucitic, assu- 

 ming such distinct features, may be found in the volcanic action, 

 : having affected the regions below the granite, in different disposi- 

 tions of its force amongst the different deposits of these elements. 

 ;It may be fanciful to suppose so, but I confess I cannot see why 

 what is called the crust of the earth is limited to the granites, and 

 why beneath those granites, there may not be rocks of a nature more 

 individualized, with large deposits of the metals, and if this should 



