THE ENGLISH CALIFORNIA. 
445 
and my only reason for mentioning them at all was to lay down 
a general rule, as applied to gold, viz., that it is never found in 
strata of Tertiary age, and Tout very rarely in those of the 
Secondary periods (except in the form of drifts, derived from 
older rocks). Indeed, as regards the Primary strata, it is almost 
always limited to rocks of the Silurian era, although it is occa- 
sionally observed in Carboniferous (coal-bearing) and Devonian 
(or old red sandstone) localities. We therefore perceive that 
the chance of finding’ the precious metal is at once considerably 
diminished by being limited to that portion of the earth’s sur- 
face which is represented by Silurian, or perhaps, to speak more 
broadly, by primary rocks. The principal auriferous regions of 
the present day are the Oural Mountains of Russia, California, 
and Australia ; and a few brief remarks on these goldfields may 
not be out of place, preparatory to detailing the position and 
features of our English gold. 
We will take the Oural Mountains first, because they have 
been known and worked the longest, and are to a certain extent 
connected with Europe; besides which, they have had the advan- 
tage of being well examined and described by Sir Roderick 
Murchison. The enormous level area of Russia in Europe is 
occupied for the most part by primary rocks, and contains no 
gold; but, oddly enough, the same rocks, when thrown up into 
the broken and inclined positions which constitute the Omni 
chain, are auriferous in a very considerable degree. These up- 
heaved ridges bear traces of great disturbance, and are pierced 
and permeated with porphyry, greenstone, syenite, and other 
plutonic rocks, the products of igneous action. 
But here we have, as we shall see in the other cases, the 
great secret of the gold deposit, or, I should more correctly 
state it, as the infallible condition which accompanies the depo- 
sit, viz., the presence of porphyry or other igneous rocks in 
primary strata — a condition which will possibly give us a clue as 
to how gold is formed. The Oural hills are nearly all composed 
of strata of Silurian, Devonian, and Carboniferous age; and the 
gold was evidently not segregated or deposited at the time of 
the formation of these rocks, or else why is it not found in the 
contemporary districts of Russia in Europe ? Moreover, Sir 
R. Murchison distinctly proved, from geological appearances on 
the flanks of these mountain regions, that the gold did not 
make its appearance until a very recent geological age ; in other 
words, that the intrusions of the igneous rocks and the appear- 
ance of the gold were contemporaneous and recent. This is 
not merely a question of scientific interest, but bears heavily 
upon the more practical one of working the gold, as we shall 
presently see. The gold-bearing hills of Australia are very 
similar to those of Russia — the rocks which lie under the drifts 
