68 Geological Society : Mr. Murchison's 



Orenburg, is subordinate to this system, in which indeed the great- 

 est saline springs of Russia occur. 



Red Sandstone, Marl, 8$c. — It is with hesitation that the authors 

 make any separation between the Permian deposits and certain 

 red and green sandstones, marls, marlstones and tufaceous lime- 

 stones, which occupy the central parts of the great trough above 

 described ; still less can they strictly identify them with the bunter 

 sandstein, new red or trias of West Europe. 



It is however a fact, that the Permian rocks with their peculiar 

 fossils are seen near Sviask, on the west of Cazan, to pass under 

 red and green marls and impure limestones, which extend over a 

 wide region by Nijny Novogorod, Juriavetz and Viasniki on the 

 west, and to Totma and Ustiug on the north. In no part of the 

 region so defined (and most of which the authors examined on a 

 previous occasion), have any fossils typical of the Permian age been 

 discovered, though the deposits in question abound in limestones 

 generally of a tufaceous character. The gypsum which occurs in 

 this member, differs from the massive white alabaster of the inferior 

 rocks, and is usually in the form of small concretions of fibrous 

 structure, often of brownish and pinkish colours. At only Vias- 

 niki on the Kliasma could the authors detect any traces of fos- 

 sils, and these are minute Cypridee, associated with apparently flat- 

 tened Cyclades ? which are imbedded in blood-red marl. The 

 thick cover of detritus which is spread over a very large area, ob- 

 scures the junction of these red deposits with the eastern edges of 

 the carboniferous limestone of the Moscow and northern regions. 

 Whatever may be the precise age of the uppermost beds of these 

 red deposits in reference to other strata in Europe, it is clear that 

 a considerable portion of the full geological succession is wanting 

 in Russia, for in various points upon the Volga, Jurassic shales are 

 seen to repose on the denuded surface of these red deposits. 



Jurassic System. — In the sketch resulting from their survey in 1840 

 (vol. xix. p. 495), Mr. Murchison and M. de Verneuil were dis- 

 posed to view certain deposits of shale and sand with concretions, 

 which in some places overlie the last-mentioned red deposits, and 

 in others rest at once on the carboniferous limestone, as the equiva- 

 lents of the lias and lower oolites. This opinion is now modified, a 

 more extensive survey having led to the belief that true lias does 

 not exist in Russia ; but that the shale beds in question, whether 

 studied in sections on the Moskwa near Moscow, on the Volga be- 

 tween Kostroma and Jurievetz, or at numerous localities in the go- 

 vernments of Simbirsk, Saratofand Tambof,are truly theequivalents 

 of the strata from the inferior oolite to the Kimmeridge clay, in- 

 clusive, of English geologists. 



It is this Jurassic group which is traceable at intervals so far to 

 the north-east, and which has been found by Capt. Strajesski as far 

 as even 65° N. lat. on the eastern flanks of the Ural chain. 



The upper members of the Jurassic system, as exhibited in the 

 South of Russia, near Izium, where they were first recognised by 

 Major Blode, differ both lithologically and zoologically from the 



