158 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 



The immediate substructure of the whole area of Russia in Eu- 

 rope is composed of the palaeozoic rocks, which on the northern 

 division are covered by sand, clay and blocks. A narrow band of 

 Silurian deposits, the older members of that group, stretches along 

 a great part of the shores of the Baltic, succeeded eastward by De- 

 vonian and Carboniferous formations, each occupying a vast extent 

 of country, and lastly that highest member of the palaeozoic order 

 of strata to which the authors have applied the term ^^ Permian 

 System,'' the most widely-spread of all, occupying a region more 

 than twice the size of the whole kingdom of France. Of the whole 

 range of the secondary deposits between the Permian and the ter- 

 tiarj'^, two only have been met with, viz. that division of the oolitic 

 series which includes the Oxford clay and its associated rocks, and in 

 South Russia cretaceous rocks, including a white chalk very similar 

 in mineral characters and zoological contents to that of England. The 

 oolitic rocks overlie the Permian, but in detached masses, and with 

 a surprising uniformity of character from the Icy Sea to the southern 

 extremity of the Urals. There are besides, but in Southern Russia 

 only, some limited tertiary districts, and of all ages, from Eocene to 

 Pleistocene. 



The most remarkable feature in the physical geography of the 

 country described, and which may justly be said to be, in the 

 words of the author, " one of the most singular features in the an- 

 cient condition of the surface of the globe which modern researches 

 have brought to light," is that exhibited by the region around the 

 Caspian ; affording the most unequivocal proofs of great changes in 

 the relative levels of the land and water, at a period geologically re- 

 cent. Over a vast region a calcareo-argillaceous deposit exists in 

 nearly horizontal stratification, abounding in freshwater shells and 

 others analogous to, and to a great extent identical with species now 

 living in the Caspian, attaining in some places a thickness of 300 feet; 

 which appears to prove, that at the time it was deposited, there ex- 

 isted an inland sea, of brackish water, exceeding in size the present 

 Mediterranean, and of which the present Caspian is the diminished 

 relic. Of this remarkable deposit, designated " Steppe " and "Aralo- 

 Caspian limestone " by the authors, 1 shall speak more particularly 

 when I refer to the Tertiary formations. 



This inland sea, although called by Sir R. Murchison a Mediter- 

 ranean, he does not the less consider to have been entirely separated 

 from the Western Ocean of that period, by a barrier, produced by 

 the elevation of the marine tertiary beds of Miocene age, on which 

 this Steppe limestone, in many places, is seen to repose. To affirm 

 with certainty that the surface of this inland sea once stood at a 

 higher level than that of the Caspian at the present day, and which, 

 according to very careful measurements recently made by order of 

 the Russian Government, is now proved to be 83,6 feet below the 

 Black Sea, would require a most extensive series of local observa- 

 tions and levellings around the region occupied by the Steppe lime- 

 stone, attended with very great difficulties. It is the opinion of 

 some travellers who have carefully examined parts of this region. 



