104 



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 Fusulinse, 

 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 recollect 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- 

 fer Mosquensis and Fusulinse are of an upper, could not have 

 doubted of the general relations and order of the strata in the chain 

 of the Donetz. 



Agreeing in the correctness of the general parallel which M. Le 

 Play has drawn between the deposits of the Donetz and the carbo- 

 niferous limestones of Great Britain, Belgium and France, I do not 

 believe that beyond this point his comparisons can be sustained. 

 The coal fields, for example, of the Low Countries and of Diissel- 

 dorf, with which I am well acquainted, do not offer, as he supposes, 

 an analogy to those of the Donetz ; for in the former, coal-seams are 

 in no instance interstratified with the Mountain Limestone series 

 of English geologists, but are invariably superposed to it. Again, 

 in the Prussian and Belgian provinces, the mountain limestone with 

 sands and shale but void of coal, reposes on a fine succession of 



* The instructions of General Tcheffkine, the works of Captain Ivanitzki, 

 and a map by Colonel Olivieri. See Journal des Mines, &c. 



