GEOLOGICAL SOCIETY OF LONDON. 



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two divisions, the lowest consisting of dark shales and ferru- 

 ginous sands, being the equivalent of the middle and inferior 

 oolitic deposits of England, and the upper composed of 

 earthy and sandy limestones, being on a parallel with the 

 coral rag and Portland oolite ; and the correctness of the 

 classification is proved by lists of fossils, including well- 

 known British species. This attenuation of a great European 

 series of rocks, was due, the authors conceive, to changes of 

 level between sea and land, whereby large areas were, for a 

 time, raised above the ocean, and again depressed beneath 

 it ; and they adduce, in support of this opinion, instances of 

 erosion or denudation in the red and green marls, before the 

 deposition of the bottom bed of the oolitic series. Though 

 these strata occupy comparatively small areas, especially near 

 Moscow, and on the Volga and Okka, they are extensively 

 distributed in the Government of Simbusk and Saratof ; also 

 on the south-west flanks of the Ural, and in the steppes of 

 the Kirghiss ; but the superior division is only known on the 

 Upper Donetz. The cretaceous system of Russia is, in many 

 respects, identical with that of western Europe, and it con- 



ains several of the long-known characteristic fossils : it occa- 

 sionally, however, presents discrepancies in composition, 

 passing in the highest part into arenaceous strata, so that the 

 fine white chalk is enveloped in masses of marlstone, sands, 

 and ferruginous grit, analogous to the upper and lower green 

 sand series of England. The tertiary strata of Russia are 

 shown by the authors to agree most strikingly with those of 

 England, the lowest bed being lithologically undistinguishable 

 from the Bognor rock, and containing fossils, stated, on the 

 authority of Mr. J. Sowerby, to be identical with Bognor 

 species ; and other beds are exact counterparts of the grey- 

 weathers of England, or the paving stones of Paris. The 

 next strata, in ascending order, are shown to be of the age of 



the Vienna basin or Miocene epoch, and the s heliy lime 



