74 VALUES OF DIFFERENT STRATA.
contained
a large number of very fine colors to the pan, but of inconsiderable
weight. The gravel from the remaining eighty-seven feet, sunk to the
bed-rock, contained coarser and heavier gold, the last eight feet
averaging from 5 to 20 cents per pan. Drifts opened from the bottom of
this shaft were systematically sampled and compared with equal
quantities taken from the layers of the upper bank. The several samples
aggregated two and a half tons, all of which were panned out carefully
in two hundred and forty tests ; and the results obtained showed that
the blue or lower gravel stratum contained $1 50 per ton, while the
white or upper gravel gave a large number of fine colors, but of
insignificant weight.
From
1870 to 1874 the North Bloomfield Mining Company washed three and
one-quarter million cubic yards of top gravel, which yielded only 2.9
cents per cubic yard and a gross profit of $2,232 84. In 1877 a rough
estimate was made of the comparative yield of the upper and lower
gravel washed during the year. The top gravel was assumed to be from a
few feet to over two hundred feet deep, and the bottom gravel
sixty-five feet deep.
The
results obtained were that 1,591,730 cubic yards of top gravel yielded
3.8 cents per cubic yard, and 702,-200 cubic yards of bottom gravel
returned 32.9 cents per cubic yard.
Patricksville Light Claim.—To
investigate more thoroughly the question a test of top and bottom
gravel was made at the Light claim, Patricksville : 58,340 cubic yards
of top gravel yielded $1,200, or 2 cents per cubic yard. The bottom
gravel (four feet deep) was then washed, when it was discovered that
two-thirds of this gravel had been drifted extensively ; but
notwithstanding this fact 4,966 cubic yards yielded $2,775 07, or 55 cents per cubic yard.
La Grange Light Claim.—A
trial of top dirt was also made at the Light claim, La Grange : 41,038
cubic yards of top dirt yielded $1,500, or 3.7 cents per cubic
