EASTERN RANGE OF THE ARCTIC URAL. 
405 
the Kakva, these deposits are interrupted, cut off and metamorphosed by the intru- 
sion of igneous rocks. 
The persistent strike of all the chief sedimentary masses of the Ural, whether 
metamorphic or unaltered, and the dominant lines of eruption from noith to south, 
of various bands of igneous rock, might, a priori, lead any observer to suppose, 
that a similar structure would be found to pervade the eastern flank of the chain 
when followed into the Arctic wildernesses. That such is truly so, has however 
only been determined by recent discoveries of Russian observers. 
The earliest expedition for this purpose was under the command of Colonel 
Protassoff, chief of the establishment of Bogoslofsk at the time of our visit to 
that place. This officer, aided by Captain Strajefski, had some years before 
explored the mines, copper veins, iron ores and auriferous alluvia on the livei 
Tolya 200 versts north of Bogoslofsk. Subsequently, Captain Strajefski was 
placed at the head of the northern explorations, and in two summers ot very 
arduous labour, he succeeded in reaching 65° north latitude. In this journey, 
often labouring for great distances through deep swamps and lofty forests, inha- 
bited at rare intervals by wild Ostiaks— tortured by swarms of mosquitoes, and 
obliged to force each step through thickets, he overcame the most trying diffi- 
culties. By this expedition, the rivers which descend from the Ural were de- 
fined, and their native names attached to them ; the rocks on their banks were 
examined, and by occasional traverses towards the axis of the chain its structure 
was determined. Proceeding from the sources of the Losva above Petropavlosk, 
Strajefski passed over the Sosva, and afterwards in succession its northern tiibu- 
taries the Nios, Bugalia, Tolya and Sigva. Supplied by him with a large sketch 
MS. Map of the whole region that he traversed, we have taken from it the few 
data which appear on our general geological map concerning this wild tiact , and 
have, for the present, deposited his original MS. with the Royal Geographical 
Society of London. 
Examining at Bogoslofsk the specimens which Captain Strajefski had brought 
back, we had no difficulty in satisfying ourselves, that Upper Silurian and Devonian, 
perhaps even some carboniferous strata (for schists with plants occur), range at 
intervals from south to north along all this eastern flank of the chain, and that 
there, as well as in the other tracts already described, these deposits, often entirely 
cut out for long distances, are usually rendered highly metamorphic, particularly 
towards the axis of the chain, by numerous intrusive rocks, ot which gieenstone 
is the most prevalent. 
3 G 
