TRANSVERSE SECTION FROM BLAGODAT TO SEREBRIANSK. 
and dipping 30° to the east. Among their fossils were a Pentamerus, closely- 
allied to P. Baschkiricus (nob.), the large Leptcena Uralensis (nob.), with Orthis 
striatula, Terebratula reticularis, corals, &c. These beds of limestone are of a dark 
colour, alternate with shale, and have altogether an unaltered aspect. Surrounded 
by eruptive and metamorpliic rocks, they constitute one of those “ oases ” or 
fragments of the original deposits, which occurring at intervals along this chain, 
serve to explain its original character. 
It would, however, be presumptuous in us to attempt to define too precisely the 
age of this isolated calcareous fragment, the Pentamerus of which led us at the 
time to consider it of Upper Silurian age ; but as we afterwards found the Leptcena 
Uralensis associated with Devonian fossils (on the Serebrianka) , the rock under 
consideration may perhaps be classed as Devonian, particularly since its corals, Cau- 
nopora ramosa, Stromatopora concentrica, and Favosites polymorpha (var. Dev.), are 
very indicative of that age 1 . The limestone is to a great extent covered by coarse 
detritus derived from the adjacent lulls, in which some calcareous specimens occur, 
amid many of an eruptive and metamorpliic character, and from which grains of 
platinum have been extracted. 
Transverse Section across the Ural from Mount Blagodai and Kushvinsk to Sere- 
briansk. — Between the Zavod of Kushvinsk and the first counterforts on the eastern 
flank of the Ural-tau or ridge, no natural sections are visible, and the road passes 
over undulations of various igneous rocks, which, according to the Russian engineers, 
consist of porphyry, greenstone, aphanite, serpentine, &c. 
At the small Zavod of Verchny Barantchinsk, talc schists are seen to be thrown 
off from a mass of greenstone, which rises into a hill called the Limetree Hill. 
From the depression to the west of this eminence, the ascent of the real Ural-tau 
or water-shed commences. The rocks discoverable on the sides of the route are 
finely laminated micaceous schists, in parts, indeed, somewhat carbonaceous, with 
occasional quartzose bands and veins of quartz 2 . The whole of the tract between 
the summit of talcose and chlorite schists and the environs of Serebriansk is, it 
must be admitted, as uninteresting and monotonous a mountain side as we ever 
1 Though the above-mentioned rock is little if at all altered, other limestones near Kushvinsk are in 
the state of white crystalline granular marble. In one of these we detected the form of Favosites Goth- 
landica ; so that this rock may be true Upper Silurian. 
* Colonel Hclmersen states that he found specimens of the quartzose micaceous schist called “ Itaco- 
lumite” near this axis. We shall hereafter advert to this rock as the matrix of diamonds. (Reise nach 
dem Ural und der Kirgisen Steppe, part ii. p. 199.) 
3 D 
