454 
IRENDYK RIDGE. — VERCH-URALSK. 
lowed on their strike, these are the very same strata which rise out from beneath 
and are associated with the carboniferous limestone in the valley of the Ural river. 
Some of these schists which have been converted into jaspers are therefore clearly 
of carboniferous, and others may be of Devonian age ; for the Silurian formations 
are all, we apprehend, represented by the rocks on the west side or near the axis 
of the Irendyk. The section which we have thus briefly described, traversing the 
river Kizilsk, terminates on the east at Yangelskaya on the river Ural ; and having 
thus brought back our readers to a valley to which we had previously introduced 
them, we will now explain to them our last traverse of the chain. 
Transverse Section of the central and most expanded region of the South Ural, from 
Verch-Uralsk to Sterlitamalc (Coloured Section, PL IV.). — This section is most 
important in re-assuring us, that large masses of rock in the very heart of the Ural 
chain are really palaeozoic, — a point which the preceding traverse does little to 
establish. It is also of high interest, from passing directly over the numerous south- 
western embranchments into which the chain ramifies in this parallel, which may 
thus be contrasted with its south-eastern limbs which we have been considering. In 
a word, our coloured section is so laid down as to carry the reader from Troitsk in 
the steppes of the Kirgliis on the east, by Verch-Uralsk to Sterlitamak, and thence 
into the great flanking plateaux of Permian rock upon the west. The country on 
both flanks of the chain, properly so called, i. e. between Troitsk and Verch-Uralsk 
on the east, and in the region beyond Sterlitamak on the west, having already been 
described, pp. 438 et seq. and 150 et seq., the section of the mountainous or cen- 
tral portion only will be now developed. 
Although porphyries and carboniferous limestone are seen to the south and gra- 
nitic rocks to the north-east of Verch-Uralsk, the substrata immediately around 
the town are obscured by black earth and alluvia, which extend for some miles to 
the low elevations on the flank of the chain, a few beds of fractured schist appear- 
ing only at intervals. The fii’st counterforts consist of bare, low bosses of porphyry 
and trap-breccia, which throw off 1 and include between them, red jaspideous schists, 
dipping sharply to the east. A valley occupied by black earth succeeds, from which 
rises a second ridge, called the Beresoiva-gora or Birch-tree Hill, with jaspers or 
altered strata on its flanks. This mass consists, in the centre, of a greenish augite 
porphyry, with amygdaloids on its sides, which to the west are flanked by a wall of 
saccharoid limestone, having a strike of north and south (10° to 15° east of north). 
A third and lesser ridge, called the Cherry Hill, is made up of porphyritic greenstone 
