The Barre daily times. (Barre, Vt.) 1897-1959, 1911-11-02

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the Sierra Nevada by waldemar Lind
gren, of the United States Geological
Survey.
The national distribution and origin
of the S300,000O00 of California gold
which has been mined from the ter
tiary placer gravels of the Sierra Nevada
is the subject of an exhaustive report
| by Waldemar Lindgren, geologist, which
has been issued by the United States
geological survey as professional paper
70.
Studies by the geological survey on
The Tertiary placer deposits of the
California Sierra began in 1886 and were
concluded about Is years later. Dur
ing this period % quadranges were
geographically mapped and IA of these
were studied in geologic detail and the
results published by the survey in geo
logic folios, Professional paper 10 in
cludes the salient features Of this earlier
work, most of which was accomplished
by Mr.. Lindgren himself. The report,
thus comprehensive in geographic scope
and the result Of careful studies, is be-
lieved to be the most complete and thor
ough description of a great placer gold
province ever published.
While In the main the report Is a
detailed description of the entire area
covered, Mr.. Lindqen's general account
Of the tremendous earth forces which
built up the Sierra, freed the gold from
its mother rock, and then brought about
its concentration in prehistoric river
channels is most impressive descrip.
tion Of continent building. Looking
backward through inconceivably long
vistas of time in which periods cover
ing millions Of years supplant the cen
turtles by which We now compute its
passage, the geologist pictures the uplift
of the new born mountain range by the
forcing upward of great bodies Of mol
ten granite. This was closely followed
BY the introduction Of veins and seams
of gold bearing quartz The resulting
highland due to this continental uplft
was then planed down by erosion in early
Cretaceous time-a geologic period many
thousands OF years before the advent
of man upon the earth.
Gold Concentrated in Prehistoric Stream
Beds.
After this erosion, and when the
mountain had been reduced 10 gentle
outlines, deep rock decay took place and
much gold was released Renewed up
lift and the formation OF sleeper slopes
resulted in greater erosion which CON
centrated the loosened gold along definite
stream channels. During this period of
most active gold concentration, faulting
and slipping Of the rock masses, with
downthrow on the east side of the
Sierra, had transformed an approximate
~ symmetrical mountain range to one
with a steep easterly slope
Tracing the long pathway Of this
early history the geologist now finds
that toward the end of what is known
as Tertiary timea comparatively re-
cent geologic period quiescent vol
canie forces vigorously reasserted them
selves, Rhyolite flows pouring from
many craters filed the valleys covered
with gold bearing grayels, deeply bury
ing the gold, and new stream courses
were outlined in the old valleys. Re-
newed disturbances and eruptions be-
gan along the scarcely healed eastern
breaks OF the Sierra, resulting in west
ward fitting of the main blocks of rock.
This encouraged deeper cutting by the
streams. which repeatedly crossed their
old courses, so that now the concentra-
tion Of gold proceeded under less favor
able torrential conditions. AT this time
volcanic vents were opened along the
crest of the Sierras, many of them
sending forth immense volumes of lavas,
ashes, and mud These great flows filled
many of the valleys to their rims and
converted almost the whole of the north
ern Sierra into desolate steaming mass
of volcanic mud. Storm waters now be-
gan the canyon cutting epoch, amazing
in its results as we see them to-day.
In many places the old rivers of Tertiary
time were exposed, and cross sections of
their valleys are now seen on the steep
canyon slopes, many of them high above
the present river beds; but large
stretches of the old river channels re-
main bIanketed beneath thousand feet
or more of volcanic mud, now hardened
into rock.
The Advent Of the Gold Hunters.
The geologic events thus outlined were
followed by the happenings of more re-
cent history. In 1910 an army of gold
seekers invaded the Sierra. They worked
first along the present streams, but grad
ually the metal was traced to the old
Tertiary river beds on the SUBMITS of
the ridges and to the quartz veins, the
primary source of all the gold in the
Sierra Nevada. Millions of dollars were
produced annually up to the seventies
OF the last century, but since that time,
owing to the prohibition of hydraulic
mining and the gradual exhaustion of
the richer channels suitable for drift
mining, the industry has slowly dimin
ished, until now less than $l,000,000
is produced annually. Mr.. Lindgren
saws: Gold is still contained in the
Tertiary channels, but the problems are
how to extract it without damage to
other property from the debris and how
to reduce the cost of drift mining so
as to permit the exploitation of the less
remunerative deep gravels."
In this connection Mr. Lindgren has
traced the old channels, and accurate
maps accompanying his report show in
detail the restoration of the Tertiary /
drainage lines.
Dredging Industry Takes the Place of |