SECTIONS FROM NIJNI NOYOGOROD TOWARDS KAZAN. 
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marlstone passing into limestone is pierced throughout by innumerable small 
cavities which branch and cross each other, and whose internal faces, invariably ol 
a dark tint, contrast strongly with the white-coloured body of the rock. Occasion- 
ally these limestones are of a cream colour and a more compact structure, with 
conchoidal fracture, and they then very much resemble what in England would 
be called freshwater limestone of secondary and carboniferous dates. We can aver 
that we have broken countless specimens of these tufaceous limestones on the Volga, 
the Suchona, the Dwina, &c., and have never yet been able to detect the trace ot 
a fossil in them, nor in the marls with which they are associated. 
At Tcheboksar the section in ascending order consists of — 
1. Red marls. 2. Greenish and chocolate-coloured concretionary calcareous grit, resembling on first inspection 
a conglomerate, but in reality more like those beds in England which both in the Newer and Older Red systems we 
know to have been formed by concretionary action (cornstones) . 3. Marls, brick-red and green, of considerable 
thickness. 4. Marls in which the courses of tufaceous limestone and marlstone prevail. 5. Slightly micaceous 
sandstone with red marl, &c. 
To the west of Tcheboksar some of the deep ravines expose cavernous limestones 
similar to those before described, surmounted by strong bands of brownish calca- 
reous grits and flagstones, and thence to Nijni the same system is continued, ex- 
hibiting certain slight lithological variations only. At Nijni, as before described, 
the group becomes much more arenaceous. 
At Nerinski on the Oka, sixteen versts south-west of Nijni Novogorod, the cliffs 
expose a band of thin-bedded gypsum, resting upon small-grained, finely laminated 
sandstone, the rippled surfaces of the strata being separated from each other by a 
thin pellicle of greenish grey marl very much resembling certain beds in England 
in the younger part of the Trias ; whilst in the upper part of the cliff, ribboned, red 
and green marls and white tufaceous marlstone, sometimes of delicate pink tints, 
abound. The gypsum of Nerinski is very different in composition and aspect 
from any which we observed in the inferior strata of the governments of Perm 
and Orenburg, or on the Dwina and Pinega ; some parts of it being lamellar, 
others fibrous, of various colours, from pure white to dark red. In other beds of 
flaglike sandstones, gypsum is disseminated in minute, brown, glassy concretions 
about the size of peas, which resemble small looking-glasses set in a dull matrix. 
When these flagstones are broken up for use (and they are the only solid stones 
around Nijni Novogorod), the small concretions glisten in the eye like fish- 
scales, and when they disintegrate, the surface of the rock has a pock-pitted ap- 
pearance. A little further, however, along the cliff the gypsum swells out and 
