430 WESTERN FLANK OF THE URAL MOUNTAINS TOWARDS SIMSK. 
before mentioned. We believe that this slaty, quartzose and occasionally cal- 
careous series, which is, in fact, repeated by upheavals and repetitions to the very 
heart and highest members of the chain, — the lofty Iremel itself being but a meta- 
morphosed grit and sandstone in the form of quartz rock, — represents the great 
mass of the Silurian system, and chiefly its lower portion. 
To the west, however, of Yuryusensk the natural features of the country change, 
the sharp and arid ridges of quartz rock and slaty schist disappear, as well as the 
eruptive rocks, and are succeeded by limestones, sandstones and shale. The strata 
exposed between Yuryusensk and Ust Kataevsk, consist of limestones, both thick, 
thin-bedded and concretionary, occasionally dolomitic, sometimes in the state of 
marble, of red as well as grey colours, with subordinate grits, conglomerates and 
schists 1 . Throughout this succession of calcareous beds, we could discover a few 
corals only, but in a limestone valley at Ust Kataevsk we met with a Spirifer, 
identical with one with which we were familiar in the unquestionable Devonian 
beds of Voroneje on the Don (see p. GO), and which we have named 8. Anossoji, 
in honour of our esteemed friend the Director of the mines ofZlataust. Here, then, 
we had a true horizon, which was soon shown to be correct ; for in a few versts to 
the west of this spot carboniferous limestone succeeds. It is important to remark, 
that whilst throughout the whole of the slaty, quartzose and older calcareous 
groups of which we have been speaking, and which we class as Silurian, the strata 
invariably plunge to the east or south of east (the younger portion of these rocks 
thus unquestionably dipping under the more ancient) , no sooner are we removed 
at a certain distance from the great convulsions which the chain has undergone, 
than all such inversion ceases. At Ust Kataevsk, where the surface is only gently 
undulated, the beds regain, in fact, their normal position, and the Devonian lime- 
stone, which to the east is inverted, dips steadily to the west-north-west, and is 
naturally overlaid by the carboniferous group. These rocks, whether in the form 
of limestone, grit or calcareous flagstone, are well seen at Yakina and Eraol ; the 
former six, the latter fourteen versts west of Ust Kataevsk, and in it we collected 
the well-known Productus striatus (Fisch.), (P. Valdaicus), with other fossils. In 
travelling from Eraol to Simsk, the road first passes over a low hill called the 
Eraolski Gora, the eastern flank of which is remarkable in this region, so void of 
all coarse detritus, by being covered with rolled and rounded fragments of syenite, 
1 The chief elevation in this calcareous tract is called Mount Soliman, the body or flanks of which 
consist of limestone, though the summit is a grit. 
