Sketch of a Classification of the European Rocks. 27 



would be to assume a more intimate acquaintance ^^ith the earth's 

 crust than we possess. Oar knowledge of this structure is in reality 

 but small, and principally confined to certain portions of Europe; and 

 even in many of these portions we are continually presented witii 

 new views and a detail of newly discovered phsenomena by able ob- 

 servers, which so modify our previously received opinions, as in ma- 

 ny instances almost to amount to a change of them. Still, however, 

 a large mass of information has been gradually collected, particularly 

 as respects this quarter of the world, tending to certain general and 

 important conclusions ; among which the principal are, — that rocks 

 may be divided into two great classes, the stratified and the unstrati- 

 iied ; — that of the former some contain organic remains, and others 

 do not ; — and that the non-fossihferous stratified rocks, as a mass, oc- 

 cupy an inferior place to the fossiliferous* strata, also taken as a 

 mass. The next important conclusion is,- that among the stratified 

 fossiliferous rocks there is a certain order of superposition, marked by 

 peculiar general accumulations of organic remains, though the mine- 

 ralogical character varies materially. It has even been supposed that 

 in the divisions termed formations, there are found certain species of 

 shells, Sic. characteristic of each. Of this supposition, extended ob- 

 servation can alone prove the truth ; and in order properly to inves- 

 tigate the subject, geologists must agree to what mass of rocks they 

 should limit the term Formation : if, as some now do, they apply it 

 to every accumulation of ten or twenty beds, which may happen, in 

 the district they have examined, to contain a few shells not found in 

 the strata above and beneath, the investigation is not likely to lead to 

 any extended conclusions. 



To suppose that all the formations into which it has been thought 

 advisable to divide European rocks can be detected by the same or- 

 ganic remains in various distant points of the globe, is to assume that 

 the vegetables and animals distributed over the surface of the world, 

 were always the same at the same time, and that they were all de- 

 stroyed at the same moment to be replaced by a new creadon, dif- 

 fering specifically if not generically from that which immediately pre- 

 ceded. This theor}^ would also infer that the whole surface of the 

 world possessed an uniform temperature at the same given epoch. 



It has been considered, but remains to be proved, that the lowest 

 fossiliferous rocks correspond generally in their fossil contents, in pla- 



* The term fossiliferotm if* here confined to organic remains. 



