The Mother Lode of California [pp. 401-412]

THE MOTHER LODE OF CALIFORNIA.4
ished, or give out altogether. On the
California vein this shifting of the orechutes will not be so apt to occur, mines
once in bonanza being very likely to
continue so indefinitely downward. Such
result would, at least, be in accordance
with experiences had here, and also on
similar lodes elsewhere.
Commencing on the north at Drytown, near the centre of Amador County, our Mother Lode extends thence
south 27~ east to the Princeton group
of mines, in the vicinity of Mount Ophir,
traversing in its course the southern half
of Amador, the whole of Calaveras and
Tuolumne, and about a third of Mariposa counties. It crosses Dry, Sutter, and
Jackson creeks; the Mokelumne, Calaveras, Stanislaus, Tuolumne, and Merced rivers, with many high ridges and
deep carions, all of which it strikes at
nearly right-angles. It forms at numerotis points a picturesque and impressive
object; the vast and wall-like masses
of glistening quartz, seen on a distant
eminence, resembling the ruins of some
ancient fortress, and contrasting in color
with the deep green chemnisal and manzanito, or shining through the foliage of
the gnarled oaks and stately pines that
half conceal them.
This vein, in its upper portions, pitches toward the east at an angle varying
from forty-five to seventy degrees, gradually assuming a more vertical position
as it descends into the earth. In thickness it varies from four or five to fifty
feet, expanding occasionally to a hundred or more. It is nearly everywhere
regularly walled and heavily cased; the
eastern, or upper wall consisting, for the
most part, of slate, and the lower of
greenstone.
In a lode of such vast proportions,
and especially of such extreme length,
the above conditions are, as might be
expected, considerably varied at different places along it. The quartz-composing the bulk of vein-matter-does not
show itself everywhere upon the surface.
For miles at a stretch it dwindles to a
mere thread, or disappears altogether;
these blank spaces alternating with
equally long section~ of croppings,
which at various points rise into lofty
cliffs, while again they appear like the
fragments of a crumbled wall, or run in
low, irregular reefs, lifting themselves
but a few feet above the ground. In
some places, the matrix, instead of quartz,
is made up largely of slate; or the ore
itself, generally carrying only free or sulphureted gold, becomes mixed with
many other metals and minerals. In a
few localities, the country rock shifts,
the greenstone and slate reversing their
ordinary position; the usually compact
and symmetrical walls become broken
and straggling, or some other anomalous feature manifests itself to complicate the structure of the vein and add to
the perplexities of the geological student.
Yet, despite these eccentricities and
local displacements, there can be no
question but this is one continuous fissure, formed by some single movement
of Nature, and filled with nearly homogeneous material throughout. The peculiarities so strongly impressed upon it
at certain points are mere accidents
exceptional and abnormal-the result of
volcanic disturbance or movements of
the earth's crust, rupturing the lode and
faulting its walls, and causing the intrusion of foreign matter; or perhaps of
these, aided by other dynamic and chemical agencies. What seems to the prospector or other mere casual observer but
a series of disjointed deposits or separate lodes, appears to the geologist a
single rent, simple and identical, cleft by
Nature in her throes to obtain rest
possibly by the force that lifted up the
Sierra Nevada, with which it corresponds in strike; or more likely by some
of those sudden and terrific convulsions
to which our globe was in its infancy so
often subjected.
I 872.]
403