CONSISTENCY OF GEOLOGY WITH SACRED HISTORY^ 425 

 IGNEOUS FORMATIONS. 



1. Products of Active Volcanos. 



' It is sufficient, for the purpose of our present argument, simply to 

 name the products of active volcanos. They are well known ; their 

 causes are now in active operation, and lava beds and currents are 

 still frequently forming, in many countries. They often bear, in their 

 very texture and features, palpable marks of the agency of fire, and 

 thus they inform us, in very intelligible language, that they are indeed 

 ignigenous : even when these features are not distinctly legible, it 

 often happens that the geographical and geological position of the 

 masses does not permit us to entertain a doubt of their volcanic ori- 

 gin. We observe their currents, and we recognize their birth from 

 fire, even when they form beds of sohd rock, which have no appear- 

 ances of scoriae, cinders, glass, or gaseous inflation, except, perhaps, 

 on their upper surfaces. No one doubts that volcanic currents over- 

 flow whatever lies in their way, and therefore we find them covering, 

 occasionally, every geological formation, and every work of man 

 which can withstand the action of heat. 



This topic was sufficiently illustrated in the introductory remarks, 

 and every one admits (what is indeed only a single instance of a gen- 

 eral truth in geology) that the superincumbent mass is, generally, of 

 more recent origin than that upon which it lies. The evidence pre- 

 sented by the eruptions of active volcanos, and the igneous formations 

 which they produce, goes then to establish the truth of geological 

 succession, but does not necessarily imply that its events are more 

 ancient than the commencement of organic life. This remark is lim- 

 ited to volcanos strictly so called, and is not intended to include the 

 unstratified rocks, concerning the igneous or aqueous origin of which, 

 there has been, heretofore, much discussion and opposition of opinion, 

 although they are now generally attributed to the agency of heat. 



% Products of Extinct Volcanos. 



Much philosophical scepticism formerly existed with respect to ex- 

 tinct volcanos. They were vaguely referred to, but without decisive 

 proof of their real volcanic origin ; and many persons, very imper- 

 fectly qualified to judge of such questions, were sufiiciently inclined 

 to infer the existence of volcanos of former ages, wherever they saw 

 a conical hill, or almost any hill, with a hollow on its summit ; and 

 porous stones, of whatever kind, were referred to a similar origin. 

 It was a very imposing and sublime idea, that volcanic fire, still active 



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