352 
ANCIENT ELEVATION OF SIBERIA ABOVE THE WATERS. 
It is on this eastern flank, where eruptive agency has been so active, that with 
rare exceptions, all the richest metalliferous ores are to be seen, whether occurring 
in veins, masses or deposits, the gold alluvia being found in the depressions between 
the elevations or on their flanks. 
The low region of Siberia into which these folds or corrugations pass, is to 
a great extent occupied by granitic rocks With very limited exceptions, true 
granites seem never to enter into the higher portions of the Ural, the culminating 
points of which generally consist of altered palaeozoic strata, usually in the state of 
quartzose and chloritic rocks, sometimes as mica schists, with saccharoid marble ; 
w T hilst promontories of greenstone, porphyry, and sienite indenting and breaking- 
in, as it -were, upon the central and subcrystalline ridge, often constitute the 
highest peaks. 
Notwithstanding, however, the striking contrast which is presented by the oppo- 
site sides of the Ural chain, we convinced ourselves that in the earlier periods, there 
had taken place all over this region, and probably extending far into Siberia, a 
deposition of Silurian, Devonian, and Carboniferous strata, which by the linear 
outbursts of granitic rocks on some lines, and of porphyries and greenstones on 
others, in lines from north to south, were thrown up into and formed this chain, 
anterior to the accumulation of the Permian deposits. As the latter have not been 
observed on its eastern flank, we may he permitted to surmise, that in those early 
periods a large portion of Siberia adjacent to the Ural, was also raised from be- 
neath the sea, and put without the reach of these waters, under which the copper 
sands and their associated marine animals were accumulated. 
On its western flank Jurassic rocks occur abundantly towards the northern and 
southern extremities of this chain, but as on its eastern flank true Jurassic strata 
occur in northern and southern patches only, and there is scarcely a trace of them 
in the intermediate country, nor, indeed, of any beds of secondary age throughout 
many degrees of latitude, we may infer that, at all events, a very large region of 
Siberia (including that portion of the eastern flank of the Ural) was not subjected 
to marine deposits during the long interval which elapsed between the formation 
of the carboniferous limestone and the accumulation of certain tertiary deposits of 
which we shall presently speak. In short, w r e hope to show, that there is no evi- 
dence to gainsay the hypothesis, that during the greater part of the secondary 
period, and afterwards during a long tertiary epoch, a very large region of Siberia 
may have been a continental mass far above the -waters. To this point we shall 
