122 PROOFS OF ASCENDING SUCCESSION FROM SOUTH TO NORTH. 
Scar limestone, near Karakuba, though we did not ourselves detect it ; and reasoning upon this fact together with 
evidences of an ascending order from south to north, and by acquiring proofs, unknown to previous geologists, of 
the existence of upper members of the series charged with Fusulinse, we completed our section by expressing our 
belief in the passage of the higher carboniferous deposits into the Permian rocks. 
We now learn from M. Le Play, that the Prodnctus giganteus, of which he collected many individuals, occurs 
at Rubejnoi on the Lower Donetz, in the southern part of the region, and he thus completely confirms our idea of 
an ascending section from south to north. Though at one time at a short distance from that spot, we unluckily 
did not visit it, but M. Le Play’s faithful detailed sections are quite sufficient for our purpose ; for after describing 
the limestone as massive and important, he says, that the mineral associations with it arc different from those 
limestones on the north, in which many more seam of coal occur than in the strata of the Lower Donetz. 
in fact, the examination ol the carboniferous region of the Donetz is one of the most striking examples which can 
be adduced, of the paramount importance to the practical miner, of the close study of organic remains in reference to 
the normal positions of the strata ; for throughout deep sections in the northern part of this territory, there is 
not a trace of the great Productus, whilst all the fossils of the middle and upper strata are present. Any one, 
therefore, who had felt as confident as we do, that this remarkable fossil was as clear an indication of a lower band 
as the Spirifer Mosqnensis and Fusulinaa were of an upper, could not have doubted of the general relations and 
order of the strata in the chain of the. Donetz. 
Nay more, the evidence now so clearly laid before us by M. Le Play, in substantiating the value of our strati- 
graphical tables, enables us also to speculate upon a parallel between the lowest anthracitic beds of this territory 
and the lower coal of the V aldai Hills, Tula and Kaluga (p. 71 etseq.). In the south-eastern limb of the country of 
the Donetz, the beds of anthracite and hard sandstone and schist which have a prevailing northerly dip, may 
fairly be supposed to rise out, like the thin coal of the Valdai, from beneath the limestone with great Producti, 
whilst the proximity of the crystalline axis of the southern steppes may well account for the indurated and meta- 
morphic character of strata which we have described under such a very different lithological aspect in the Valdai 
Hills and in the governments of Tula and Kaluga, where they occur almost in their original condition of sand 
and clay, and are far removed from the influence of all intrusive rocks. 
Agreeing in the correctness of the general parallel which M. Le Play has drawn between the carbonife- 
rous deposits of the Donetz and the carboniferous limestone of Great Britain, Belgium and France, we do not 
believe that beyond this point his comparisons can be sustained. The carboniferous deposits, “terrain houiller,” 
for example, of the Low Countries and of Drisseldorf, with which wc are well acquainted, do not offer, as he sup- 
poses, an analogy to those of the Donetz ; for in the Rhenish provinces coal-seams are in no instance interstratified 
with the Mountain Limestone series of English geologists, but are invariably superposed to such rocks. Again, in 
these Prussian and Belgian districts, the mountain limestone with sands and shale, but void of coal, reposes on an 
elaborate succession of Devonian and Silurian rocks, loaded with typical fossils ; whilst the group of the Donetz, 
unlike that of the north of Russia, is exclusively carboniferous to its base, and rests at once on very ancient cry - 
stalline rocks, or abuts against porphyries and other eruptive masses. 
And even it we admit that there is to some extent an analogy between the carboniferous rocks of South Russia 
and the Low Countries, in both being overlaid by cretaceous deposits, wc must also not omit to recognize, in 
the one case, the presence of intermediate strata of the age of the Zechstcin, and in the other the total absence 
of that deposit. 
The true foreign analogy, therefore, of the coal strata of the Donetz, considered in reference to other deposits 
of the same age, is to be found in the north-western or Lake districts of England, where some seams of coal 
lie below and others are interstratified with the mountain limestone series and its sandstones and shales. 
The coal-field of Berwickshire, or that below the mountain limestone, is much richer in contents than the south- 
eastern portion of the tract of the Donetz, which we believe to be on the same parallel ; whilst in identifying 
the rest of the succession, or the great mass of the Donetz, with that of the Mountain Limestone group of 
Northumberland and the Yorkshire dales, the comparison, as to amount of produce, is largely in favour of the 
Russian deposits. 
