Russia and the Ural Mountains. 531 
sections on both flanks of the Ural Mountains, that, in becoming 
part of a mountain mass, this system, so uniform and so peculiar 
over a space as large as an ordinary European kingdom, put on 
many of the features which are so well known to those who have 
studied the carboniferous limestone only in the western parts of 
Europe. 
We further learnt, that, in the absence of any deposits to repre- 
sent our great coal-fields, the earboniferous system was succeeded, 
in ascending order, by a vast series of red and cupriferous deposits 
to which we have assigned the name of Permian. It will not, 
therefore, be arrogant on our part to say, that we entered upon 
the examination of the territory of the Donetz, in the possession 
of elements of comparison which no previous travellers had ac- 
quired. 
Knowing, from the maps and instructions furnished to us by the 
Imperial Administration of Mines*, that the major axis of this tract 
and the main direction of the strata trend from west-north-west to 
east-south-east, we resolved, after terminating our researches in 
Southern Russia, to examine the chain of the Donetz in parallel 
lines transverse to its general strike; and, by carrying out this scheme, 
we arrived at the conclusion, that the oldest member of the series 
occupies its southern frontier, and that, after a multitude of flexures, 
the central strata dip under a limestone charged with Fusuline, 
fossils which we had invariably found in the uppermost bands of 
limestone; the whole group being surmounted in the valley of Bach- 
muth by the equivalents of the Permian system. One striking de- 
ficiency, however, attached to our reconnaissance, and fortunately 
it has been supplied by M. Le Play himself. Those members of 
the Society who heard our memoirs read, will recoliect the import- 
ance we attach to the presence of the large Productus giganteus, as 
uniformly characterizing (over vast regions in Russia) the lowest 
beds of the carboniferous limestone ; and, as we now learn from M. 
Le Play, that this fossil, of which he collected many individuals, 
occurs in the southern part of the region, our idea is thus completely 
confirmed of an ascending section from south to north. 
In fact, the examination of the carboniferous region of the Do- 
netz is one of the best examples that can be adduced, of the 
paramount importance to the practical miner of the close study 
of organic remains, in reference to the normal position of the 
strata; for, throughout deep sections in the northern part of the 
same territory, there is not a trace of this 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 remark- 
able fossil was as clear an indication of a lower band as the Spiri- 
Ser Mosquensis and Fusuline are of an upper, could not have 
doubted of the general relations and order of the strata in the chain 
of the Donetz. 
* The instructions of General Teheft'kine, the works of Captain Ivanitzki, 
and a map by Colonel Olivieri. See Journal des Mines, &c. 
