RESUME AND CONCLUSION. 
583 
extended conditions of climate in those days than in our own. With some subdi- 
visionary distinctions of mineral character, the chalk of Russia is in a remarkable 
degree analogous, both in mineral and zoological contents, to that of England, whilst 
some of the lower tertiary beds which overlie it are perfectly similar in their fos- 
sils to strata of the same age in the London and other basins. The miocene, or 
middle tertiary deposits, are, in truth, nothing more than continuations of those of 
Austria and the Danube, known to be identical with the shelly beds of the north 
of Italy. 
In treating this portion of our subject, we have specially dwelt upon a great 
physical feature regarding the former geography of the terrestrial surface, to which 
little or no attention has been previously paid. The steppe limestones of the 
south of Russia and those surrounding the Caspian, Azof and Aral seas, are shown 
to have been relics of an enormous inland sheet of water, fully as large as the pre- 
sent Mediterranean, and probably having had scarcely any communication with the 
ocean. This opinion is strictly derived from the evidences of the organic remains, 
which, whether imbedded in limestone cliffs at 200 or 300 feet above the sea, or 
lying loose in the sands of the lower steppes, are all species perfectly distinct from 
those of the ocean of this or any former date, but identical with or analogous to 
forms now living in the present Caspian and Aral seas. 
In the north of Russia marine deposits with existing oceanic shells occur, also 
indicating periods approaching to our own ; and it has further been shown, that vast 
accumulations of foreign drift, which encumber the surface, have been accumulated 
under the waters of the sea. Finally, we have attempted to point out the manner 
in which certain subaqueous deposits were desiccated, and how after passing into 
lands they have been smce modified. 
This long register, from the earliest traces of organic existence, has been read 
off, notwithstanding the prevalent absence of those facilities which are offered to 
the observer in other countries. In western Europe, the various strata are often 
so inclined, that the succession of several formations is frequently seen in escarp- 
ments occupying the breadth of a few miles only. The case, however, is not so 
in Russia, where the whole series of deposits, over an area nearly as large as all 
that part of Europe to which geologists have hitherto attended, may, with very 
slight exceptions, be termed a great horizontal mass, the undulations and denu- 
dations in which alone enable us to decipher its details of succession, by travelling 
over the enormous spaces which any one of its members occupies. But however 
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