314 
MORE RECENT DEPOSITS OF THE FORMER CASPIAN. 
chain in which plutonic rocks appear. The existence of red sandstones, probably 
palaeozoic, but at all events long anterior to the tertiary deposits, supports his view, 
whilst the presence of the recent steppe or Aralo-Caspian limestone over nearly 
the whole surface of this isthmus, proves decisively, that sea-bottoms of that age, 
elevated from north to south, and directly in the line of upheaval of the Ural Moun- 
tains, effected a great change in the physical outlines of these regions, at a period 
which, though geologically recent, must have been long antecedent to the historical 
aera. 
Having before stated that the Aralo-Caspian deposits repose, along their north- 
western frontier, upon older oceanic strata, it is clear, that subsequent to their 
accumulation, these last-mentioned beds and other submarine masses must have 
been heaved up and formed into barriers which prevented the spread of the ancient 
inland sea. It is also evident, that at a later period, a large portion of that sea 
was thrown off, and its bottom raised into great plateaux of steppe limestone. We 
venture to believe, that these results are distinctly referable to at least two periods 
of vibration between land and water, which took place before the earth’s surface 
was inhabited by our race. For as the steppe limestone above alluded to, has all 
the appearance of having been the shore of certain low r and sandy steppes to which 
we now invite attention, so do we believe that the latter was still the abode of the 
same ancient, eastern Mediterranean, when its waters being considerably dimi- 
nished, entered into deep recesses, and united the present insulated seas by straits 
and channels, the bottoms of which have since become dry land. 
In thus carrying on the attention of the reader to this branch of inquiry, we beg, 
however, to guard him against the inference, that other changes of sea and land in 
the North of Russia, particularly those which involve the great phenomenon of the 
erratic blocks, may not have been effected anterior to some of the last desiccations 
of these lower steppes. We have merely deemed it expedient, when explaining the 
successive retirements of the Aralo-Caspian Sea, to consider in the same chapter 
the -whole series of changes of adjacent sea-bottoms into continents, and to show 
that all such grand mutations are, properly speaking, geological phenomena, which 
ought to be considered apart from superficial detritus not clearly proved to be sub- 
marine, as well as from minor undulations between land and water which have taken 
place within the historic sera. 
Lower Steppe deposits of the former Caspian . — Our readers will perceive that we 
have distinguished upon the Map, a large portion of Southern Russia by a lighter 
