CARBONIFEROUS LIMESTONE OF THE SOUTH URAL. 
131 
from the banks of the Bielaya and its tributary the Salaust, is exposed in a most in- 
structive anticlinal form, the strata dipping sharply to the east and west. To 
the east they plunge at a moderate angle beneath other flaggy limestones with 
gypsum ; whilst to the east the beds are almost vertical, and terminate in a great 
fault or depression, in which the Bielaya runs from north to south (see coloured 
section, PL IE fig. 1.). 
The limestone is of light grey and brownish colours, and is in part a mass of 
shells. Among these we identified Productus antiquatus, P. lobatus, P. punctatus, 
P. spinulosus (Sow.), Spirifer lineatus (Sow.), P. quadriradiatus (nob.), Lepkena 
sarcinulata (Hupsch.), Terebratula pleurodon, Orthis Michdini, O. arachnoidea, Or- 
thoceratites, and the little Trilobite of the Valdai Hills, Otarion Eicliwaldii. On 
the whole, the beds which are exposed, may be of rather younger age than those 
to which we have just alluded, as occupying the western flank of the mountains, 
but there are no traces of the overlying Goniatite grits. 
To the south of the parallel of Sterlitamak, the outer zone of carboniferous lime- 
stone soon subsides, but the direction of an anticlinal line is continued far to 
the south of Orenburg, as will be hereafter explained, in describing the Permian 
rocks at Grebini, &c. 
We did not follow the inner carboniferous zone, which is marked upon the Map, 
as continuous from the south-east of Sterlitamak to the gorges of the Bielaya, 
where that river escapes from east to west ; but if the ridges be continuous from 
north-north-east to south-south-west, it is evident that the strike of the strata 
must be very oblique to the course of the hills, — a phenomenon, indeed, by no 
means peculiar. To the south, however, of the Bielaya, the carboniferous lime- 
stone occupies a number of small ridges parallel to each other, and all trending 
from north to south, as beautifully and correctly expressed in a MS. map presented 
to us by General Perofski, and a slight expression of which is attempted in our 
small general map of the Ural. In these ridges, however, the geographical out- 
line is in perfect harmony with the strike of the strata. Occupying a zone of 
some breadth, this carboniferous limestone, in which we found fossils character- 
istic of both its highest and lowest members, ranges down to the Sakmarka, 
where that river flows transversely to the chain '. 
1 It is in the midst of this band of parallel ridges of limestone that the country quarters, (Katchufka) 
of General Perofski are situated, amidst some of the many beautiful landscapes which the South Ural 
affords. 
