Geology of Bussia. 79 



the size of the whole kingdom of France. Of the whole range 

 of the secondary deposits between the Permian and the ter- 

 tiary, two only have been met with, viz., that division of the 

 oolitic series which includes the Oxford clay and its asso- 

 ciated rocks, and in South Russia cretaceous rocks, including 

 a white chalk very similar in mineral characters and zoologi- 

 cal contents to that of England. The oolitic rocks overlie the 

 Permian, but in detached masses, and with a surprising uni- 

 formity of character from the Icy Sea to the southern extre- 

 mity of the Urals. There are, besides, but in Southern Rus- 

 sia 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 fea- 

 tures in the ancient condition of the surface of the globe 

 which modern researches have brought to light,'' is that ex- 

 hibited by the region around the Caspian ; aifording the most 

 unequivocal proofs of great changes in the relative levels of 

 the land and water, at a period geologically recent. 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 existed 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-Cas- 

 pian limestone" by the authors, I shall speak more particu- 

 larly when I refer to the Tertiary formations. 



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

 diterranean, he does not the less consider to have been en- 

 tirely 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 



