The San Francisco call. [volume] (San Francisco [Calif.]) 1895-1913, 1895-12-08
NEW TUNNEL TO BE STARTED.
Six Miles of an Ancient Riverbed,
With Pay Gravel Six Feet
Deep, in Sight.
ESPECIAL Correspondence Of THE CALL

OCCupdllOIiS 10 waiting, IllOuSu LuOSc w 10
have waited have been the winners. This
has been especially true of the mining in
terests of this State, and is just now being
emphasized on the Forest Hill divide in
Placer County, in the Gray Eagle and adj
jacent gravel mines. Stockholders have
come and gone, assessments discouraging
many and compelling retirement, but
some have stayed to the finish and are
now riding on the crest of the revival
wave in mining industries.
Prominent in this class is T. G. Burning
and his associates in the Gray Eagle mine.
For twenty years Mr.. Durning's faith in
regard to the possibilities of the Forest
Hill divide has not waned. He has in
vested his money in its properties, has
cheerfully taken up the stock of dis
couraged spectators, has bored a shaft
$50 feet from the top of the central eleva-
ton of that section to the ancient river
bed below, and then, starting in at the
Owl Creek Canyon level, has penetrated
the side of the hill with magnificent
tunnel 5000 feet in length, which has
yielded tons of pay gravel, the recent rich
strike in free gold rewarding his efforts.
The Forest Hill divide is known as that
portion of Placer County lying between
the north and middle forks of the Ameri-
can River, though locally the northern
portion of this area is included in the Iowa
Hill divide, so called from its principal
town and centers of mining industry.
geographically the Forest Hill divide is
a plateau, elevated from 1900 to 5000 feet
above corresponding points of the bound
ing river canyons, but broken and cut up
by tributary canyons and ravines, the gen.
eral surface rising eastward at n average
rate OF about 100 feet to the mile. Geo
logically its mass is composed of the COM
mon Sierra country rocks, states, lime
stones and serpentines, the whole being
capped by lavas and volcanic ash and
mud deposits. Underlying the latter
formations and superimposed on the true
country rocks are enormous diluvial de-
posts, lying in the rocky beds of an an
cient buried river system. This was I'M
questionably what is now the system of
the American River, its extent, however,
being much greater.
Mining operations and the recent care
full surveys and examinations made by ex-
pert mining engineers demonstrate the
extent of the buried system to be not less
than 200 miles OF channels. The surveys
further show that although there are sew
eral distinct systems Of channels buried,
crossing and eroding each other, the gen.
eral trend is to the southwest and toward
the lower emo of the divide, westerly from
q line drawn between the small towns of
Todds Valley and Yankee Jims.
All OF these ancient channels, with the
possible exception of those eroded off COM
pletely by the middle fork of the American
River, seem to be within one comparatively
narrow bedrock depression, presumably
being the main channel of at least one of
the ancient systems. The linear extent of
this channel depression, taking the me-
anders into account is certainly about six
miles. 1t has been bottomed at only one
point-about midway-and that in the
Gray Eagle drift mine. Though super
hcialy better defined than most of the an
Gent river channels, it is probably the
least known of any of them. owing to the
fact that its rims of natural rock are so
wide as to deter the running of tunnels in
the face of the uncertainty of the depth re-
quired for drainage. The Gray Eagle tunnel,
however, has removed the uncertainty as to
the depth required, and at the same time
has demonstrated that they have the KEY
TO the whole situation, in that the other
mines of the divide, if worked tably,
must be operated through the Gray Eagle
tunnel. To this end new tunnel, about
5000 feet lower down the canyon than the
present tunnel, is TO be mined out, thus
assuring absolute drainage of all the ad-
iacent mines. without recourse to pump
ing. The present Gray Eagle tunnel is
not only self draining, but furnishes the
water motor with power in forcing in the
air supply.
All of the buried river channels carry
more or less gold in their channels or
eroded drifts. AS compared with existing
river channels of the same locality they
have, so far as mined, yielded much richer
re turns. In fact. the Forrest Hill divide
channels have yielded in the immediate
vicinity of Forest Hill, Yankee Jims and
Todds Valley, fully s2O,OO0.0OO. the limits
of the mining being two and six miles east
erly from the site of the proposed new
Gray Eagle tunnel. Except at Bath and
Forest Hill, practically none of the min
ing has been done in the main channels,
but in benches, in tributaries and on the
veins of the main channels.
The Gray Eagle people already have
splendid tunnel from the beginning to
breast and the air connections are first
class. It's total length is about 5000 feet.
The whole breast of the tunnel is of hard
cemented gravel. The depth. or height,
of breast is between seven and eight feet.
The gravel extends above the roof and
also below the level. From the bottom
for distance of three feet, splendid ap-
pearing and very blue gravel fecked with
gold is in evidence, which is the upper
part OF the pay ore. his blue gravel eX-
tends down and connects with the bed
rock. The gravel which lies Immediately
on top of the blue gravel extends all the
way up to the roof and is an entirely diff
ferent formation. 1t is not cemented quite
as hard as the blue and is of gray sandy
color and character.
The tunnel is in great channel, which
has, at some time, been the bed of
mighty river. the great depth of gravel
and its cemented character, ever water
worn and ball-like form: of its gravel and
large powders, which are worn to the
smoothness of glass, and the wall-like
form of it's rim rock on each side, clearly
proves this opinion to be correct. This
being the case, the richness Of the mine
and its adjacent properties cannot be
doubted. Taking as criterion the rich
ness of the other mines IN The same di-
vide, Superintendent Burning firmly be-
lieves his people have one of the greatest
and best mining properties of its kind in
California.
At a point several hundred feet back
from the breast crosscut has been run to
the south vein. AT this point the channel
is about 125 feet wide. From the bottom
OF this crosscut winze has been sunk to
depth of about six or seven feet and no
signs of bedrock in the bottom. The
gravel for the whole depth would pay, but
the water is too strong, hence the neces-
Slty of the DrODOSed lower tunOel The