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RELATIONS OF CRETACEOUS TO TERTIARY STRATA. 
ition between the secondary and tertiary rocks of Southern Russia, and we the 
more adhere to this view, because we never yet have seen an instance of the surface 
of the white chalk of Russia, or of any beds which we could call cretaceous, having been 
eroded as in Western Europe. On the contrary, at Volsk, Kui’sk and other places 
cited on the Donetz and the Don, the white chalk seemed to form a part — often 
indeed a central part — of a continuous series of sands and argillaceous strata to 
which it was subordinate ; and when in addition it is stated, that the lower tertiary 
fossils occur in beds of nearly a similar character, we think our inference is well 
sustained. 
But if their succession be truly indicated, there is still the greatest difficulty in 
assigning precise relative boundary-lines upon a map, to the cretaceous and tertiary 
deposits. Should our opinion be correct, that nature has not placed any clear 
barriers between them, such lines can be laid down only after many years of ela- 
borate survey. And even then, very extensive districts occupied by white and grey 
claystones and sands, with marls, in which no fossils can be detected, must be 
subject to doubtful interpretation. In certain districts, it is true, the evidence is 
clearer. To the west of Simbirsk, near Drechetilof ka, for example, there are strata 
incumbent upon the chalk, in which M. Jasikoff has detected characteristic tertiary 
fossils. It would also appear that the so-called cretaceous strata near Sarhtof are 
overlaid by patches of the same age, just as it has been shown, that the white chalk 
is surmounted hy the shelly beds of Antipofka. To the south and west, however, 
of that place, in the tract extending by Tzaritzin to Sarepta, and in all the space in 
that latitude, between the Volga and the Don, the white chalk receding far to the 
west, we have great hesitation in asserting that the upper steppes between Sarepta 
and the Don, are truly tertiary, as represented on our Map 1 . We have, however, 
stated, that at Piattisbianskaya to the south of Golubinskayaand on the right bank 
of the Don, we met with escarpments of white, grey and green, minutely micaceous 
claystone, marlstone and sandstone, &c., which we group with the chalk. The 
formation there occupies arid hills, 200 or 300 feet in height, which present a 
1 That our readers, unacquainted with the vast distances which must be travelled over in Russia, may 
not think we omitted any means within our reach to arrive at sound conclusions in classification, we 
may state, that we were compelled to travel most rapidly (often day and night), and in excessively hot 
weather (August 1841), through these tracts of the Volga and the Don, in order to be able to reach and 
examine the steppes of the sea of Azof and the coal-field of the Donetz, before the bad weather of the 
autumn. In fact, being much hurried and compelled to view some districts with less accuracy than others, 
we naturally sacrificed the cretaceous and tertiary to the palaeozoic and carboniferous rocks, particularly 
as the Imperial Government attached more importance to our report upon the latter. 
