The hydraulic press., 1859-08-13
THE BLUE LEAD.

lucky when they have found It, and which
they pronounce to be the channel of an an
cfent river. This lead is always found rest
ing on or near the bedrock, beneath diluvi-
al strata of different colors, such as shades
of red, yellow and gray, and is itself more
of deep slate color than blue. 1t is gen.
orally richer in auriferous particles than the
gravel lying above it, and forms the produc-
tive drift diggiegs for which the vicinity Of
Forest City is noted, as well as those of many
other localities. The theory of its origin
alluded to above is predicated upon these
facts md assumptions that it has been
traced in continuous line at a certain alti-
tude through several counties, from ridge to
ridge, at right angle to present water cour-
ses, across caRons thousands of feet deep !;
that the qualification of the lead is uniform
and different from that of adjoining gravel
deposits that tree trunks, both in the lig-
neous and petrifed state, are found lying in
it as though borne there. by freshets; and
that the gold found in it is everywhere of
the same character as to appearance and
quality. This crude theory conforms to the
general one which is popularly employed to
account for the extensive alluvial deposits
constituting our placer diggings. 1t is re-
markable that the majority Of our miners,
who are commonly men of Intelligence and
practical knowledge in their pursuit, should
have discarded entirely, if they ever enter
tained, when speculating upon the origin of
our gold fields, the more rational theory of
marine influence, for one of purely local
causes. They overlook all the facts which
go to prove total submergence cftkis coast
at some remote period, and settle down upon
the narrow idea that the immense gravel beds
which contain so large portion of our min
eral wealth, and which extend at least four
hundred miles north and south, having an
average breadth OF probably not less than
sixty miles, were deposited by rivers which
anciently ran here and changed their cham
nels from time to time until they had paved
the whole country with cobble stones =
These deposits have been cut through by
modern streams running different course,
and hence the present canons and ridges
of these ancient rivers the one that deposi-
ted the blue lead has alone left distinctive
marks fits course. Now, unfortunately for
the plausibilty of this theory, the blue lead
is found all the way from the summit of the
H., ~, r.. I. n
being confined to a certain altitude and a
certain line, it exists at every altitude, on
the main ridges as we'll as on spurs of them.
and even on isolated peaks. Its color is ow-
ing to the presence of sulphuret of iron in
solution, without which the gravel would
not be any different from that lying above,
except that the boulders and largest stones
would be found in it as they are always found
at the bottom of every gravel deposit
Wherever sulphurous acid or sulphuret of
iron is found, there the SO called blue lead
will be discovered, just as certainly as red
earth and gravel will be found where the
oxide of iron is present as coloring agent
1t is found at great elevation in Sierra
county, and at low one in Nevada and Yuba.
1t has been struck at San Juan and at points
thirty or forty miles above it, leads of other
colors intervening. Having such variety
OF location the blue lead also exhibits a
varying inclination of its strata, though
generally the inclination, like that of all the
| gravel beds, is towards the great valleys, as
though occasioned by the gradual subsiden ce
of vast body of water. Tree trunks are
found in it to be sure, as they are in other
leads, where they were probably borne by
identical causes. Some of them we have
seen are completely coated with sulphuret
of iron, the material of the wood in some
instances being gone and this mineral occu-
pyihg its place, presenting the exact appear
ance as to shape and grain of the old log.
The alleged uniform character of the gold
taken from the blue lead is another error
The external appearance of gold always de-
pends upon the nature of the material in
which it has been imbedded. If it has been
buried in red earth where iron oxide was
plentifully present, it will be coated or col
ored by that mineral and present uniform
appearance whatever its degree of fneness
may be. And so if it be found in the blue
lead will it lock like specimens from the same
kind of deposit far away and of much finer
or poorer quality.
Ii is timewe began to have rational views
on the subject of the gold deposits Of our
wonderful State. Notions more consistent
with the vast processes of nature would give
greater confidence to the miner, and lead to
more extensive enterprise with view to eff
/ fecing new discoveries. The immense gravel
ranges which slope in parallel lines towards
the valleys from the summit of the Sierra
Nevada, are not.more than prospected vet.