MAGNESIAN LIMESTONES OF ORENBURG, GREBENI, ETC. 
147 
Between these hills and Orenburg the country subsides into an undulating 
steppe, in which it is very difficult to trace any regular succession, though dark red 
sandstone with some gypsum occurs, a little out ot the high road, and other strata 
contain concretions of impure limestone not unlike “ cornstone.” These concre- 
tions, and the matrix in which they occur, are indeed more like the Lower New Red 
Sandstone of the central counties of England than any other rock to which they 
can be lithologically compared, and in approaching Orenburg we again saw them 
at the little station of Nejinskaya, where the rock is a dull, brown-red sandstone 
with purple streaks. 
At Orenburg, the right bank of the Ural river exposes cliffs of red and light- 
coloured marly incoherent sandstone, and this system of red beds extends over a 
very considerable area to the south, north and west of the city. 
Zone of Zechstein, or Magnesian Limestone . — Having conducted our readers to 
some distance from the edge of the carboniferous limestone, as seen on the flank of 
the Ural Mountains, and having ascertained, by their high inclination, that many 
of the intermediate strata are of great thickness, we may now state, that on this 
parallel we met with a band of limestone which is dissimilar in mineral aspect 
from that which is associated with the gypsum near the mountain flanks. Some 
courses of this limestone are perceived near to Orenburg, about four versts west of 
the city, and near the mouth of the river Sakmarka. The upper beds are thin, 
and of light grey colour, but they thicken downwards to courses of eight and ten 
inches of whitish colours. The strata exposed (and they have been quarried to 
shallow depths only) form probably the upper part of the Zechstein, properly so 
called, and they contain Terebratula elongata and another species, with some reed- 
like plants and serpuloid bodies. This rock is here evidently upon a line of undu- 
lation or elevation, for the beds plunge to the south-south-west at 25°. 
About sixty versts, however, to the north, the same limestone is admirably ex- 
posed at a place called Grebeni, and is extensively quarried as a building stone tor 
the use of the surrounding country. The hill of Grebeni is on the left bank of the 
river Sakmarka, to which it presents an escarpment of not less than sixty feet in 
height, from which the beds dip to the east-south-east at an angle of 20° to 30°. 
This portion of the valley of the Sakmarka evidently marks a line of elevation and 
dislocation, for on traversing this low ground to the hill of Palatki, about six versts 
from Grebeni, we found the same limestone in a reversed position, and dipping 
