727 
of the insulated hill of Monte Bogdo, is shown to consist of a mem- 
ber of the Permian group, surmounted by fossiliferous limestone, 
which probably belongs to the Jurassic system ; and it has before 
been shown that the rock-salt of Iltetzkaya Zatchita (anté, p. 695), 
south of Orenburg, is subordinate to this system, in which indeed the 
greatest saline springs of Russia occur. 
Red Sandstone, Marl, 5c.—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 ona 
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 Cypride, 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 
(ante, p. 403), Mr. Murchison and M. de Verneuil were disposed 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 equivalents 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 Rus- 
sia; but that the shale beds in question, whether studied in sections 
on the Moskwa near Moscow, on the Volga between Kostroma and 
Jurievetz, or at numerous localities in the governments of Simbirsk, 
Saratof and Tambof, are truly the equivalents of the strata from 
the inferior oolite to the Kimmeridge clay, inclusive, of English . 
geologists. 
It is this jurassic group which is traceable at intervals so far to 
the north-east (anté, p. 403), and which has been found by Capt. 
