The record-union., 1899-08-27

were wider and slopes sleeper than the
present rivers. Through many centur-
| les rain and frost disintegrated the
rocks, and the rushing rivers carried
the detritus down toward the valleys.
| The numerous quartz veins in the
mountains were thus broken up, and
/ the freed gold, being heavy, collected IN
| the beds of these rivers, While the
| lighter detritus was transported far
| ther down. The beds of these old rivers
! constitute what are to-day called the
auriferous gravel channels. They owe
their richness to the enormous amount
Of erosion which had taken place, an
amount considered by biologists to
have been equal to layer of rock sew
eral thousand feet in thickness. After
these auriferous channels were thus
filled and the gold collected in the
gravels, volcanic eruptions occurred,
and immense streams of molten lava
hundreds of feet deep flowed directly
down their beds In this way the au-
riferous gravel channels were covered
or buried by what is called the lava
| cap. When these masses of lava cooled
and hardened, the rivers of the present
ward from the mountains, and natur-
| ally sought the softer and lower por-
tions, and owing to the hardness of the
| lava often formed channels by the side
of the ancient beds. We see the result
of their cutting in the canyons of the
present streams which are often one or
two thousands feet deep. The old bur-
! led rivers under the lava are therefore
high above the present ones. A great
mountain ridge, or divide extends
! for many miles from the main range.
| Hundreds of feet below the top of this
divide, and buried deep under lava is
/ the graveled channel of a Pliocene
river. On each side of this great ridge,
and one or two thousand feet below
| the bed of the old buried river, flow the
rivers of to-day. The new streams, in
cutting their channels, often cross and
recross the old ones. and thus washing
out the gold the Californian pioneers
| found SO abundant in the streams
| Miners run long tunnels into the
sides of these divides" or ridges, un-
| til they reach the old gravel channel
carrying the gold. The lowest or rich
est portion of this gravel is then mined,
and by drifting removed. If it is hard
and "cemented," it is crushed in stamp
mills and the gold saved; or if it is not
cemented, the gravel is placed on wash
| ing floors, and a stream of water under
pressure turned upon it by which it is
disintegrated and the gold freed and
saved, the rock, sand, earth, ETC., pass
ing away down the fumes. This bot
tom cement gravel pays from So to
SO per mine carload. and when they
breast out from 30 to 150 feet wide on
the channel and six to eight feet high,
the channel will yield from 800 to 5000
per running foot, and often very much
higher. These lava capped divides COW
ering the buried rivers are found in
many counties in the upper part of
California.
AS stated, when these old river chan
nels are under the lava they are drift
ed" When there is no lava Gaping
and only bank or deposit from 80
| to 80 feet high covered with trees,
shrubs, etc, the hydraulic process is
used, and the mass is washed away.
The hard lava Gaping of the old riv-
ers has resisted the elements better
| than the softer rocks. so that what
were formerly the lowest point, or riv-
ers, are now the higher mountain
ridges. In some places the bones and
teeth of elephants and other large ami
mails are found and pine cones and
leaves are taken out as fresh looking
asl those of to-day, but they soon crum-
bic on exposure to the air.
In hydraulicking very much larger
amount of dirt has to be handled than
in drifting but the process is cheaper.
bitches, reservoirs and pipe lines are
built, and water brought to the mine
under heavy pressure. This is thrown
against the bank through a nozzle, or
giant" as it is called. and tears down
the gravel at a wonderful rate. Tun-
nels are run, in which blasts of powder
are placed and the bank is thus shaken
up. Sometimes 10000 or 10000 pounds
of powder are exploded at one time,
disintegrating many thousand cubic
yards of earth which the water then at
tacks The material thus washed down
passes through fumes or sluices, where
| the gold is caught in rifles with quick
silver, the rock and earth passing on
to dumping place. In this way all
labor of shoveling or handling is avoid
/ ed, and immense amounts of material
may be moved in a short space of time.
/ 1t can be imagined how much material
/ is moved by hydraulic mining when it
i is stated that the bulk of this aurifer-
| Gus earth is only worth ) or cents a
cubic yard; yet these mines in the hight
of their prosperity yielded $4,000, 900 or
| S10,000,000 a year. Mines of this char
aracter are quite expensive to open
and equip, since so large a water sup
ply has to be provided. and bitches,
reservoirs, fumes, ETC.. have to be built
and maintained. Therefore the larger
| and more productive ones are only
worked by large companies.
| There was serious controversy in
! California about this class of mining,
which lasted some years. In washing
away the high banks or hills, the deb
| ris, or tailings, as the waste material
| is called, filled in and injured the navi-
| gable streams and the farming lands
along their banks. Long and costly
and bitter controversy between the
farmers of the valley and the miners of
the mountains finally resulted in clos
| ing the hydraulic mines down by in
| functions of the United States courts,
and these mines, large and small, We're
| compelled to stop work wherever their
| debris went into the main streams or
their tributaries. Thus great produc-
tive hydraulic mining properties, with
their extensive ditch systems, reservoirs
and mining plants. in which about
| 100000 600 were invested, became un-
productive and valueless. This condi-
tion of affairs continued for some years,
and the annual gold product of the
State fell off materially.
| The towns and camps in the hydrau-
] lie mining regions of the State became