GENERAL VIEW OF THE ARALO-CASPIAN DEPOSITS. 
323 
whose relics have been mentioned, or as we would express it, of two elevations ol 
the land, during the long period whilst the surface was assuming its present out- 
line. In reference to the former Eastern Mediterranean, we can well imagine how 
similar species should have exclusively prevailed over so vast an area, so long as 
the same waters covered all the low tracts from the low country south-west ol 
Orenburg to the Black Sea, and how a sensible change of animal life should have 
accompanied the diminution of the Caspian to its present dimensions and the union 
of the Black and Mediterranean Seas. 
General view of the Caspian Deposits. — In terminating our reflections upon the 
Aralo-Caspian deposits, we beg to impress upon the reader, that without attempt- 
ing to enter into details, our principal object has been to demonstrate the existence 
of a former vast, interior brackish sea, the remains of which have an uniform, 
limited and peculiar physiognomy, which cannot fail to he regarded as one of the 
most singular features in the ancient condition of the surface of the globe which mo- 
dern researches have brought to light. Though the effort to synchronize precisely 
these Caspian deposits with oceanic marine strata of other parts of the world is 
obviously no easy matter, we have still good grounds for believing, that on the 
whole they are the equivalents of Pliocene and Post-Pliocene deposits ; for on the 
one hand they clearly overlie strata of Miocene age, and on the other are inti- 
mately linked on to the inhabitants of the present Caspian. 
In respect to the actual degree of saltness of the Caspian, the analyses ol 
M. Gobel, on which we rely (p. 308), are strengthened by the opinion of M. Eich- 
wald, who thus writes : — “ I can assure you that the Caspian is much less salt 
than the Black Sea, and possesses one-sixth part only of the saltness ot the ocean. 
Its water, however, is very acrid and disagreeable to the taste on account of the 
bitter salts and naphtha which it contains in such quantities that few animals can 
now exist in it 1 .” 
We have already explained, that we believe the great saltness ol some parts of 
this sea is due to brine springs issuing from the bowels ol the earth olten from 
rocks formed long anterior to the earliest Caspian deposits. But whether this be 
so or not, we base our general inferences upon the simple fact, that shells iden- 
tical with those now living in the Caspian— to the exclusion of nearly every oceanic 
species — are spread over the lands ol vast countries, and have been left at aif- 
1 Letter to M. de Verneuil, in which M. Eichwald, extending this reasoning, infers, that the former 
Caspian probably contained more species than the present sea (May 1844). 
