154 COSMOS. 



been confounded with granite, and sometimes contains zir. 

 coniurn, and of the pyroxenic nepheline discovered by Gum- 

 precht near Lobau and Chemnitz. 



To the second or sedimentary rocks, belong the greater 

 part of the formations which have been comprised under the 

 old systematic, but not very correct, designation of transition^ 

 flotz or secondary, and tertiary formations. If the erupted 

 rocks had not exercised an elevating, and owing to the simul- 

 taneous shock of the earth, a disturbing influence on these 

 sedimentary formations, the surface of our planet would have 

 consisted of strata, arranged in a uniformly horizontal direc- 

 tion above one another. Deprived of mountain chains, on 

 whose declivities the gradations of vegetable forms, and the 

 scale of the diminishing heat of the atmosphere appear to be 

 picturesquely reflected furrowed only here and there by 

 valleys of erosion, formed by the force of fresh water moving 

 on in gentle undulations, or by the accumulation of detritus, 

 resulting from the action of currents of water continents 

 would have presented no other appearance from pole to pole 

 than the dreary uniformity of the llanos of South America, or 

 the steppes of Northern Asia. The vault of heaven would 

 everywhere have appeared to rest on vast plains, and the stars 

 to rise as if they emerged from the depths of ocean. Such 

 a condition of things could not however have generally pre- 

 vailed for any length of time, in the earlier periods of the 

 world, since subterranean forces must have striven in all 

 epochs, to exert a counteracting influence. 



Sedimentary strata have been either precipitated or de- 

 posited from liquids, according as the materials entering into 

 their composition are supposed, whether as limestone or argil- 

 laceous slate, to be either chemically dissolved, or suspended 

 and commingled. But earths when dissolved in fluids im- 

 pregnated with carbonic acid, must be regarded as under- 

 going a mechanical process, whilst they are being precipi- 

 tated, deposited, and accumulated into strata. This view 

 is of some importance with respect to the envelopment of 

 organic bodies in petrifying calcareous beds. The most 

 ancient sediments of the transition and secondary formations 

 have probably been formed from water at a more or less high 

 temperature, and at a time when the heat of the upper fi-ir- 

 fiicc of the earth was still very considerable. Considered in 



