of a Geological Survey of Russia. 421 



esting phenomena of the Ural Mountains, the examination 

 of which occupied us nearly three months. We there studied 

 alternately the wonders of the gold alluvia, the sites of the 

 entombment of your great mammalia, and sought for the causes 

 of the astonishing metamorphism of the sedimentary rocks 

 of that chain. For an explanation of the last class of pheno- 

 mena, the works of Humboldt and Gustaf Rose must always 

 be consulted. I will on this occasion simply say, that far from 

 being ■primitives as was supposed, this chain, with the excep- 

 tion of its eruptive masses, is entirely composed of Silurian, 

 Devonian and Carboniferous rocks, more or less altered and 

 crystallized, but in which nevertheless we have been able to 

 recognize in a great number of localities my own Pentamerus 

 Knightii*, and many fossils which clearly define the age of 

 the other strata. These rocks, though much broken up, are 

 arranged in parallel bands, the mean direction of which in 

 the North Ural is from N. and by W. to S. and by E., 

 whilst in the South Ural, trending N. and S., they assume a 

 fan-shaped arrangement, spreading out towards the southern 

 steppe of the Kirghis, where, interlaced with porphyries and 

 other trap-rocks; they are often converted into the far-famed 

 jaspers of this region. 



Still less can I now pretend to treat of the great carbonife- 

 rous region of the Donetz ; for without entering into details 

 concerning this southern tract, so valuable to the future in- 

 terests of Russia, I cannot render it the justice which it merits. 

 Still I may say to you as a geologist, that its numerous beds 

 of coal (bituminous and anthracitic), with its grits and shales, 

 are completely subordinate to the mountain limestone series, 

 and represent in no sense the coal-fields of Great Britain, Bel- 

 gium, and France. 



In concluding, however, I must tell you of a very inter- 

 esting discovery we made in returning from Taganrog to 

 Petersburgh. Count Keyserling took the line of Voroneje 

 and the Don, and M. de Verneuil and myself that of Koursk, 

 Orel and the river Oka, and on meeting at Moscow our results 

 completely'agreed.f It was, as you know, generally believed 

 up to this moment, that central Russia presented a regular 

 succession from older to younger deposits as you proceeded 

 from north to south. This is not the case. A great axis of 

 Devonian rocks or old red sandstone, having a width of at 

 least 120 miles, rises in the heart of the country around Vo- 

 roneje and Orel, and stretches to the W. N. W., in which 



* Silurian System, p. 615. 



t Colonel Helmersen, so distinguished for his geographical and geologi- 

 cal researches in Russia, also examined the tract near Orel in the course of 

 the summer, and had come to the same conclusions as our party. I was 

 however unacquainted with his opinion when I wrote this letter.— R. I. M. 



