of the Northern and Central Begi&ns of Bussia. 139 



theory, it being now apparent, that the lithological nature of the most 

 ancient subsoil of Russia in Europe is such as to compel geologists to re- 

 ject the conclusion, that, in proportion to their antiquity, the strata have 

 been hardened or crystallized by any general radiation of central heat ; 

 for in these wide tracts such crystalline and hardened state is clearly seen 

 to be purely metamorphic, and dependent exclusively on the vicinity of 

 rocks of igneous protrusion, in receding from which to the south all 

 the strata described are at once found in their normal soft condition. 



In taking leave of the Societ}^ the authors explain some of the chief 

 objects of their journey to the Ural Mountains, Orenburg, &c., on which 

 they were about to proceed. 



P.S. After these sheets were sent to press, Mr Murchison received 

 letters from his friends and fellow-travellers, the Baron A. de Meyen- 

 dorf and Count A. Kej^serling, in which the researches of these gentle- 

 men in the south of Russia are explained. These letters communicate 

 important additions to the results already offered to the Geological Societj^ 

 particularly in regard to the extension and development of the carbonifer- 

 ous system. The geological map which has been prepared by their la- 

 bours, and from those of other Russian authorities, agrees with that of 

 Mr Murcliison and M. de Verneuil, exhibited to the Society, in the funda- 

 mental classification of the rocks which occupy the northern and central 

 governments of Russia, and in the lines of demarcation between the 

 Silurian, Devonian or Old Bed, Carboniferous, Newer Red, and Oolitic 

 Sf/stetm J but it is copiously enlarged, by shewing the extension of the 

 carboniferous system over a very wide area, ranging from near Witepsk, 

 by the south of Tula and Kaluga, to the S.E. of Cazan. A vast spread 

 of chalk and tertiary deposits directly overlies these carboniferous lime- 

 stones, which rise again from beneath these younger formations in the 

 great carbonaceous tract of the Donelz, the southern edge of which 

 consists of the granitic steppe. A section made by Count Keyserling 

 and Professor Blasius to the south of Kaluga, indicates a succession 

 from what these naturalists believe to be the lower beds of the carboni- 

 ferous limestone, containing the Spirifer Mosquensis, into superior strata 

 of sand and shale with coal, subordinate to bands of limestone containing 

 the Productus hemisphcericus, the coal being associated with much red 

 earth, and overlaid by the upper carboniferous limestone. They also 

 express their belief that the millstone grits which have been alluded to 

 near Moscow must be considered of tertiary age, as similar beds overlie 

 true chalk. 



Mr Murchison takes this opportunity, in the name of his friend M. 

 de Verneuil and himself, of recording his sense of the value of the ad- 

 ditional data which are due to the labours of Baron de Meyendorf and 

 his associates, and trusts that after an exploration of the flanks of the 

 Ural, and other tracts near Orenburg and in the south, all the chief facts 

 will have been obtained for the construction of a general geological 

 map of Russia in Europe* 



