402 THE URAL CHAIN ONE GREAT SERIES OF DEPOSITS. 
tions and great breaks to which all the strata have been subjected in this tract, the 
uppermost beds of the Silurian are brought to the surface and throw off the lower 
beds of the Devonian, as in the vicinity of Bogoslofsk. 
It was sufficient for our chief purpose to satisfy ourselves, that the limestones, 
however crystalline and altered in some parts of their strike, as in the adjacent 
tract of luryinsk, were nothing but palaeozoic rocks, and of this fact the section 
of the Kakva offered us the most convincing proofs. To have worked out the pre- 
cise succession of the strata in so convulsed a region was wholly impracticable 
during our cursory survey. 
Equally convincing and more elaborately detailed illustrations of this phenome- 
non are, indeed, given by Colonel Helmersen, who in extending his descriptions of 
it to the banks of the Vagran and Sosva near Petropavlosk, has shown bow on 
these streams, as well as on the Turya near Bogoslofsk, the fossiliferous limestones ' 
and their associated beds are variously dislocated, mineralized and changed (in- 
cluding passages into dolomites, saccharoid marbles, jaspers, hornstones, &c.) when 
in contact with or in the proximity of the greenstones and porphyries of those 
districts. His observations form a valuable geological illustration of this territory ; 
whilst M. G. Rose fully explains the mineral distinctions throughout the eruptive 
and crystalline rocks around Bogoslofsk, and has pointed out that the greenstone 
porphyry traverses not only the sedimentary deposits, but also the metamorphic 
garnet rock which had probably resulted from a previous eruption of another mass 
of matter in fusion (greenstone). (Rose, p. 400.) 
In concluding this chapter, it may be observed, that the transverse sections 
of the Ural which have been described, explain phenomena clearly which are 
obscurely seen only upon the route from Perm to Ekaterinburg. They show us, 
that if not throughout the chain, at least on both its flanks and wherever the strata 
are not highly altered and crystalline, their age can be recognized by organic re- 
mains. Whether we look to the uppermost Silurian and the Devonian limestones, 
cut oft and left in isolated fragments amid igneous masses on the east of the chief 
ridge, yet succeeded by Devonian and (as on thelssetz) by carboniferous rocks, or 
1 In considering the fossils collected in the Sosva, Vagran and Tura, to be Upper Silurian, Colonel 
Helmersen has added, that they are probably of the same age as the limestone of Livonia, which lies 
between the Esthonian (Lower Silurian) limestone on the one hand and the Devonian rocks on the other. 
Judging from the corals he has seen from several of these localities, some of which he believes to be new 
species, Mr. Lonsdale thinks that Devonian rocks are prevalent in the region east and north of Bogos- 
lofsk. (See his description in the sequel.) 
