Old Mines of Southern California: Desert-Mountain-Coastal Areas Including the Calico-Salton Sea Colorado River Districts and Southern CountiesFairbanks, Harold W. (Harold Wellman)
History
Old Mines of Southern California: Desert-Mountain-Coastal Areas Including the Calico-Salton Sea Colorado River Districts and Southern Counties
Fairbanks, Harold W. (Harold Wellman)
Geology -- California, Southern; Mines and mineral resources -- California, Southern
The Ready Relief has several levels, all of which are connected by
winzes and shafts. The huge bunches of quartz have, from their peculiar
form, been denominated “rolls,” and I know of no better term which would
convey a clear idea of their appearance. As a result of close
observation made at numerous points in the mine and on the surface at
the time of my visit, I formed the conclusion that the “rolls” of the
Ready Relief Mine simply represent an exaggerated condition of the same
sort of flexing of the schists that has produced the other mines of this
district. The facts as observed lead me to the belief that the “rolls”
or folds of the Ready Relief Mine, and its extensions, both north and
south, are the result of a severe compressive stress upon the schists at
right angle to a line running nearly northwest and southeast; that this
force was exerted in the form of pressure and not of contraction; that
as a result of this pressure there is a tendency exhibited on the part
of the contorted strata to form a reverse fault and not a normal one,
and that this power expended itself before the rocks were forced to
yield to the strain to the extent of fracture, the result being an
abrupt crumpling of the schists without disruption.
Along this line of disturbance percolating waters have deposited silica
in enormous quantities. The schistose folded masses having been
completely metamorphosed, massive quartz replacing the crushed and
crumpled crystalline rocks, though the lines of its former schistose
structure are in many places preserved.
A sketch of a characteristic section is here reproduced, and it may help
the reader to form some conception of this unusual occurrence of
gold-bearing quartz. The strike of the country rock is about northwest
and southeast, and varies but little from this over a wide area. The
rock is, generally speaking, a dark gray, rather close-grained,
micaceous rock (argillite), having a dip to the east of about 80°. The
succession of folds cut across the dip of the schists at an angle about
45° from the horizon.
It will be noticed that in places several of the rolls lie side by side.
Where this occurs the pay shoot is very large. The thickness of the
individual rolls varies from a few inches to 5 or 6 feet, and where the
folds parallel each other a width of 12 to 20 feet or more is not
uncommon. These rolls do not extend longitudinally a great distance, but
seem to gradually diminish, being followed by others along the strike of
the vein. It seems quite evident that had the stress which produced this
folding or crumpling of the schists proceeded much farther an abrupt
fracture must have resulted, and the Ready Relief vein would have been a
fissure having a dip of about 45°.
At the time of my visit the Bailey Bros. were overhauling their mill of
ten stamps and were putting in a 12-foot waterwheel of the Pelton style.
Public-domain text, read in full here on John Shaqi.
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