Scientific Travellers. 293 



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 reofion of the Donetz: for without enlerino; 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 agreedf- 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 

 direction it probably connects itself with deposits of the 

 same age in Lithuania and in Courland. This discovery 

 seems, indeed, to have an intimate relation to one which we 

 made in entering Russia early in the spring, near to Schavli 

 in Lithuania, of much red ground and a band of upper Silu- 

 rian rocks. In fact it also explains the cause of the great 

 difference which exists between the deposits of the carbonife- 

 rous basin of the Donetz and those of your Moscow region, 

 now proved to constitute a vast basin. For as the two seas, in 

 which these deposits were accumulated from high antiquity, 

 were separated by the ancient lands in question, so must we 

 infer that the conditions and nature of their shores, their rivers, 



* Silurian System, p. G15. 



t Colonel Helrnersen, 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 wa' 

 however unacquainted with his opinion when 1 wrote this letter. — R. I. M 



