458 
SILUEIA. 
[Chap. XIX. 
let me also here advert to my suggestion concerning the era at which the rocks 
were impregnated *. It has been already stated that when the metal is found in 
situ it is chiefly in metamorphosed strata of Silurian age, occasionally in De- 
vonian, very rarely in Carboniferous ; and it is certain that in the Ural Moun- 
tains the gold was segregated in separate masses in these formations at a 
comparatively modern geological period. In the first place, the western flank of 
the Ural chain offers clear proof that the process had not been effected when 
the Permian deposits were completed. During that period vast heaps of 
pebbles and sand, all derived from a preexisting Ural chain (the older stratified 
rocks of which had even then undergone much change), were spread out for a 
length of many hundred miles over the lower country on the west. Together 
with fragments of all the rocks, sedimentary or igneous, which are known in 
the chain, specimens of magnetite and copper-ore, large quantities of which 
abound in the range, are not uncommon in these Permian deposits so largely 
worked for copper-ore ; but nowhere do they contain traces of gold or platinum. 
Had those noble metals then existed in the Ural Mountains, surely some por- 
tions of them must have been washed down together with the iron- and copper- 
ores, jaspers, and other minerals, and, being indestructible, must necessarily 
have formed part of the old Permian conglomerates. On the contrary, when the 
much more modern debacles that destroyed the great animals, and heaped up 
the piles of gravel just described, affected this chain, then the debris was 
auriferous. It is manifest, therefore, that the original Uralian rocks were 
charged with gold during the intervening time — that is, between the Permian 
period and that of the Mammoth-Drift. 
What, then, was probably that geological period in the northern Ural ? We 
cannot assert that it occurred shortly after the Permian era, nor even when 
any of the Secondary rocks were forming, since no golden debris is found even 
in any of the older Tertiary grits and sands which occur on the Siberian flank 
of that part of the chain. If, then, the Mammoth -Drift be the oldest mass of 
detritus in which the gold of this region occurs abundantly, we are led to believe 
that in this region the noble metal, carried up by igneous rocks, was only 
brought together into rich veins at comparatively recent periods. At the same 
time it is by no means improbable that, where the older rocks are flanked by 
Secondary deposits, particularly in the South-eastern flank of the Ural chain, 
where eruptive diorites abound, the fragments of which contain gold, some of 
these may have been rendered to some extent auriferous after the accumulation 
of such Secondary strata, as to the south of the Lake of Aushkul (p. 454). 
In the sequel it will be shown that such operations have occurred during the 
Secondary periods in South America and California f. 
* See the work on Russia and the Ural Moun- 
tains, vol. i. p. 472 et seq. 
t In many instances gold is, I know, associated 
in the same veinstone with other ores, — such as 
silver, or argentiferous galena, and various ores 
of copper and iron — magnetic iron being, in- 
deed, a very frequent accompaniment, whilst the 
association with tin-stone has before been alluded 
to. Such occurrences do not invalidate, but 
strengthen, the view derived from the phenomena 
in the Ural Mountains ; for as copper- and iron- 
ores are frequently found in old conglomerates or 
Sebble-beds of Secondary age, and lumps of gold 
ave never been detected in them, I see no means 
(explain the phenomena as we may) of evading 
the inference that no notable quantity of gold-ore 
was formed in the Ural Mountains until the com- 
paratively recent epoch indicated in the text. In 
the work ' Russia and the Ural Mountains,' vol. i. 
p. 473, the inference is thus stated : — " Whether, 
therefore, we judge from the total absence of au- 
riferous matter in the ancient [Permian] conglo- 
merates on the west, and in the Tertiary grits on* 
the east, or from the absolute materials in the 
whole series of regenerated deposits, we conclude 
that the chain became [chiefly] auriferous during 
the most recent disturbances by which it was 
affected, and that this took place when its highest 
peaks were thrown up, when the present water- 
shed was established, and when the syenitic granite 
and other comparatively recent igneous rocks 
were erupted along its eastern edges." 
The reader who wishes to have fuller informa- 
tion on the subject of Uralian and Siberian gold 
must consult Humboldt's 'Asie Centrale,' and 
' Reise nach dem Ural,' &c, by Humboldt, Rose, 
and Ehrenberg, with the valuable mineral de- 
scription by M. Gustav Rose, various memoirs by 
