12^ PROCEEDINGS OP THE GEOLOGICAL SOCIETY. 



rally name him when I have occasion to refer to the authors, I hope 

 I shall not be considered as detracting in the least degree from the 

 merits of M.. de Verneuil and Count Keyserling. 



: Geology OF Russia. 



Russia in Europe is " one huge depositary basin," encircled on the 

 west and north by the granites of Sweden and Finland, and on the 

 north-east, east and south-east by the chain of the Ural Mountains, 

 which are mainly composed of plutonic and metamorphic rocks. It 

 consists, to a very great extent, of a series of undulations, composed of 

 incoherent clays and sands ; but although in that unindurated state, 

 not consisting of modern detritus, but being very ancient deposits that 

 have undergone no consolidating process ; for the whole of European 

 Russia appears to have been exempted from igneous agency; no erup- 

 tions have tilted up the beds, but the elevatory forces, to which how- 

 ever it has been indubitably and repeatedly subjected, have raised the 

 vast undulating plains en masse, without a break. The oscillations of 

 the land having left the strike more or less horizontal, scarcely any 

 traces of unconformability of strata of different ages are to be met 

 with, and beds separated in time by vast intervals are in the same par- 

 allelism of juxtaposition as if they were the members of one group. 

 Thus at the mouth of the Vaga, a tributary of the Dwina, about 

 150 miles south of Archangel, post-pliocene beds are seen resting 

 conformably on limestones with Product! and Corals of the Per- 

 mian rocks ; and an observer unacquainted with fossils might view 

 the two as parts of an unbroken series. 



We have some most instructive examples of similarity of litho- 

 logical characters between deposits of the most different ages, con- 

 sequent perhaps in some degree upon that absence of consolidating 

 processes to which I have alluded. A grit occurs in Sweden, de- 

 scribed as a recomposed granite or granitic gneiss, which consti- 

 tutes the base of the Silurian system in that country, that can 

 scarcely be distinguished in mineral character from a tertiary grit 

 in central France. Lower Silurian deposits charged with fossils 

 common to the crystalline slaty rocks of other regions often occur 

 as greensands and half- consolidated mud-like limestones. We have 

 Silurian bituminous schists that resemble the hard beds of the Kim- 

 meridge Clay. In one region a carboniferous limestone has all the 

 characters of a soft tertiary deposit ; in others, Devonian, Carbo- 

 niferous and Permian rocks are not distinguishable from the younger 

 secondary or even tertiary deposits of Western Europe ; and even 

 an oolitic rock of Miocene age cannot be distinguished from the 

 Great Oolite of the Jurassic period. 



These facts are most valuable, as showing that at all periods sedi- 

 mentary rocks were formed, as they must now be forming, at the 

 bottom of the sea, from the detritus of adjoining land, by the same 

 agencies of disintegration as are now at work ; and that then, as now, 

 gravel, sand and mud were the forms which such detritus must have 

 taken, to be afterwards compressed together, and consolidated by a 

 variety of causes acting more or less intensely in different situations. 



