18 . II. RELICS. Introduction 



Agency by which, the deposition of organic bodies 

 has been effected in the mineral regions. 



and comparatively superficial state, over various tracts of country, 

 were not the same as those, by which vegetable remains have beesi 

 infixed, at the greatest depths, in the earth, and made integrant 

 parts of solid strata neither, it is almost needless to add, can we 

 suppose, that exactly the same natural operation could, at one 

 time, form accumulations of sea-shells and corals, and deposited 

 them in calcareous strata, and, at another period, collect the re- 

 mains of plants only, and bury these in beds of argillaceous matter. 

 As, however, a diversity in the time and mode of introduction 

 into the mineral kingdom, will scarcely be denied to extraneous 

 fossils, it only remains with us to point out the theory, which, in 

 our opinion, best agrees with the principles just stated,the founda- 

 tion of those assumed above, as our text. 



It is evident, that a theory of the mode, in which organic bodies 

 have become subjects of the mineral world, includes, in fact, a ge- 

 neral inquiry into the formation of the earth, since extraneous fossils 

 exhibit some of the principal phenomena, on which such an inves- 

 tigation must be founded. The various theories hitherto devised 

 for illustrating the primitive state, as well as the present structure, 

 of our planet, have been reduced to two classes. The Vulcanic 

 and Neptunian the first referring the origin of most mineral 

 phenomena to Jlre; the latter, to water. Of these two classes the 

 last has most consistently adapted its principles to the facts, which 

 extraneous fossils present ; and, among the different " theories of 

 the earth" constructed by the Neptunists, that of WERNER, or at 

 least that, which the geologists of his school propound as his, 

 seems best calculated to stand the test of experimental inquiry. 



Neither the limits nor design of this introduction, however, 

 permit us to give a detail of the Wernerian system of geology 

 in all its parts; but, in the following sketch will be found most of 

 its leading propositions ; or, at least, such of them, as more im- 

 mediately apply to the object of the present work to these arc 



