SECTION FROM YERCH-URALSK TO STERLITAMAK. 
455 
and felspar rock on its eastern side, and of slaty stratified porphyry on its highest 
points, dipping sharply to the east. 
Though here of much less altitude than in the Irendyk, it is thus evident, that 
these low hills, which are on the direct continuation of that ridge, are composed 
of precisely similar intrusive rocks and of stratified masses, having on the whole 
the same inclination and strike (see Map, Pl. VII.). A narrow valley is then 
passed, which covered hy black earth on the surface, is occupied beneath by a 
coarse and slightly auriferous ancient alluvia, which is watered by the small river 
Mindak, whence the ascent of the chief central ridge commences 1 . The eastern 
spur of this ridge, called Muchty, exposes serpentine, followed by schists with 
quartzose veins, doubtless those from whence the gold alluvia in the adjacent valley 
have been derived ; and after passing several bosses of felspathic and trappsean 
rocks with talcose schists having sahlbands of serpentine, the summit is found to 
be composed of talcose, quartzose and micaceous schists, with veins of quartz, &c. 
In an adjacent depression, called Bursuk, the schists are black, with large masses 
of quartz, both in veins and concretions, the schist itself containing carburet of 
iron. These talcose and schistose rocks, rolling over in great flexures in which 
the easterly dip is most prevalent, rise up into the chief mountain (Gara-tash 2 ), 
composed in great part of glossy fractured quartz rock, around the base of which 
the road meanders. These quartzose masses, in parts chloritic, in parts micaceous, 
and having on the whole a greenish tint, have so much the aspect of primary rocks 
that some portions of them have been described by Colonel Helmersen as gneiss. 
They roll over (though the dip is mostly to the east) and also occupy the western 
slopes of the mountain which descend by Uzuk-tash towards the Zavod of Bielo- 
rietz. 
To the east of this Zavod, and also on the banks of the river near the works, 
1 The northern prolongation of the Irendyk is here separated by this depression of the Mindak or 
Mindiak from the heights of Gara-tash, which are the direct southern extension of the ridge, to which in 
the central and northern mountains of the chain the name of Ural-tau is confined. Seeing that this latter 
ridge (Gara-tash, &c.) subsides gradually in its range to the south and is lost in the elevated plateau of 
the Sakmara, we consider that from this parallel of latitude the Irendyk being the watershed, must be 
viewed as the true southern limb of the Ural-tau. Notwithstanding, therefore, the separation of the 
ridges by the narrow valley of the Mindak, they are here so nearly confluent, that the Muchty Hill which 
we are describing may be looked upon as a connecting link between them, if the geographer wishes to 
follow the most continuous line of heights which separates the waters flowing to the east and west. 
2 The summit of Gara-tash is 2370 French feet, or upwards of 2500 English feet above the sea. 
3 n 2 
