DESCRIPTION OF THE MAPS IN VOL. I. 
661 
In venturing to colour, geologically, the wide tract between the Ural river and the forts of 
Constantinovsk and Michaelovsk in the Kirghis steppes on the east (to which our own 
researches did not extend), we simply desire to generalize the valuable facts obtained 
through the explorations of Colonel Ilelmersen and Captain Tchaikofsky. The first-named 
has, indeed, shown that the Djabyk Karagai, or northern end of the Kara-Edir Tau, is a 
continuation of the same granitic range which we traversed between Miask and Troitsk : 
also that the other eruptive rocks on either flank of the granite are greenstones, porphy- 
ries, serpentines, &c., which have altered and metamorphosed the palaeozoic strata, as on 
the east flank of the Ural Range, producing in like manner chloritic schists, quartz rocks, 
granular limestones, &c. ; whilst in some of the limestones, encrinites and other organic 
remains occur at intervals. This range of Djabyk Karagai or Kara-Edir Tau, is seen in 
the General Map to be confluent with the Mugodjar ridge, which is a southern prolonga- 
tion of the Ural ; and in perusing our pages the reader will find, that the granite of the 
Siberian and Kirghis steppes, which occupies such large surfaces from Miask, and ex- 
tends at intervals by Ekaterinburg to Verkhoturie on the north, is, as already stated, the 
most recent eruptive rock of these regions. 
Our extreme eastern limit of the palaeozoic, eruptive and metamorphic rocks, which are de- 
pendencies of the Uralian chain, is necessarily to some extent arbitrary, particularly to 
the south of Troitsk ; for, though at certain points, such as Verkhoturie and Kamensk, we 
have seen tertiary accumulations succeed, we can by no means assert that they are con- 
tinuously extended to the south. The range of such tertiary deposits must, we know, be 
circumscribed, since we have, by the examination of fossils and rocks from various parts 
of Siberia, convinced ourselves, as before observed, that the same palaeozoic, eruptive and 
altered rocks which are laid down on the Map, Plate VII., occur at numerous intervals 
throughout Siberia in all its breadth from west to east ; an inference that has been extended 
to the shores of Kamtschkatka and the Isles of Shantar, in the Sea of Okhotsk, through the 
explorations of M. A. Erman and Professor Middendorff. 
In colouring this Map, we have, as before said, adhered to our old principle, of representing 
all eruptive rocks under different tints of the same colour. Thus the greenstones, syenites 
and porphyries (5) are in the darkest tint of red ; the serpentines (5) have waved vertical 
lines on a base of red ; and the granites (b 3 ) are in a lighter red ; all of them being made 
distinct from the pale red of the azoic rocks of Scandinavia, as represented in the other 
Map, Plate VI. 
Of the Uralian Map, Plate VII., we need say no more, particularly as we have in the text and 
elsewhere acknowledged with gratitude our obligations to General Perovski and others 
(especially to M. J. Khanikoff), for materials which have given to the southern portion of 
the chain so fresh a geographical character. (See Journal of the Royal Geograph. Soc. 
vol. xiv.) 
