164 
PERMIAN ROCKS IN NIJNI NOVOGOROD AND SIMBIRSK. 
the south and west, the limestone having sunk beneath them, are entirely com- 
posed of the overlying marls and sands, which occupy so vast a space to the 
west and north, and of which we shall treat hereafter. The cliff exposed on the 
west side of the town of Sviask, and under the chief monastery, exhibits about 
forty feet of limestone, covered by about ten to twenty feet of sand and detritus, 
viz. 
] . Strong beds of dark grey, bluish limestone, in parts earthy and foetid, with courses of flint. 2. Grey lime- 
stone. 3. Marly argillaceous beds. 4. Impure limestone. 5. Concretionary strata of yellow magnesian lime- 
stone, with nodules of pure flint, in beds from three to fifteen inches. 6. Fissile marls. 7 . Thin-bedded, cream- 
coloured, yellow and white marly limestone, with conchoidal fracture. This is the highest bed in situ. The fossils 
are the same as those of Verkni Uslon and Shevalagheena, in short, the characteristic forms of the deposit wherever 
we have examined it. 
The examination of this limestone in the environs of Kazan affords some results 
of interest, for it proves to us, first, that in passing from east to west the lower beds 
with gypsum gradually disappear, and that the upper masses of the fossiliferous 
rock are eventually lost under a great accumulation of variegated marls and sands ; 
secondly, that in this western portion of its range, the iimestone no longer inos- 
culates with sands, plants and copper grits, as in the districts nearer to the Ural 
Mountains, but is a more homogeneous mass of calcareous or pure siliceous matter ; 
and lastly, it is evident, that even in the space of a few miles, the beds, though 
containing similar fossils, vary exceedingly in their lithological structure. 
Western and Southern Limits of the Permian Rocks in the Governments of Nijni 
Novogorod and Simbirsk. — In reference to the eastern boundary of the carboni- 
ferous limestone, the beds of which with Fusulinse are worked at the village of 
Schwetzi, in the district of Sudovo, thirty to forty versts north-west of Murom, 
we may now observe, that the nearest beds of Permian limestone which we could 
detect are at the little village of Teplova on the river Tiosha. Unfortunately the 
space between these tw T o limestones of different age (about ninety versts) is so ob- 
scured by loose sand, that we found it impossible to discover the succession of 
strata which fill up this interval. In our journey from the west, it was at the 
village of Teplova, about fifty-six versts west of Arzamas, that we first met with 
the limestone of which we are now treating. The beds at this spot are yellowish 
(magnesian), marly, and spotted by manganese, with some disseminated concre- 
tions of flint. Though of no great thickness they are quarried for building pur- 
poses. The fossils are neither abundant nor well-preserved, but among these are 
the Retepores, generally found in the range of the system through Perm and 
