Los Angeles herald., 1910-09-25

1nt illSlOTy VI 1NtNdhG NOuAAAyB WhiNi
is a chronicle of mining discovery and
activity, with the later accompaniment
of successful agricultural, horticultural
and other industrial developments,
dates back sixty-tWo years to the
summer following the discovery OF
gold in the mill race at Coloma. the
early gold hunters energy was directed
to the gravel beds bedrock crevlces
and bars" of the live" flowing
streams of our foothills; the rivers,
creeks and ravines were soon covered
with the thirty-foot or 100-foot square
claim of the pioneer day, and 1t was
but q matter of about one year When
the pick and shovel were being directed
toward the hunt for the true
source of the placer gold. Two sources
were found: The one in the outcrop-
ping vein of quartz of Gold hill and
Massachusetts hill of Grass valley ana
the other source in the buried dead
river" channels of the high hilltops or
the Yubas, the Bear river, Greenhorn
creek and Deer creek.
From 184S Nevada county mas peen
and now continues to be q pronlnent
California factor in the development
Of the mining laws; in the perfecting
of mining methods and in the produc-
tion of gold bullion for the commerce
of the world 1t has been a training
school in which have been studleu lhe
reouiRements of the law of the apex,
of extralateral rights ana bounuary
rights, and the problems OF geology Oh
the economies of management OF el-
ficjencies of mechanical and metallur-
gical appliances, and in conjunction
with the mining operations, has oe-
veloned the application of hydrauIc
and electric power and now enjoys Ine
reliability of the double unit or these
powers, furnished by private or genera
service water storage and power oe-
velopment plants.
DESCRIPTIVE GEOGRAPHY
Nevada county extends from the
Ca1ifornia- Nevada state line at the
east. up through the valleys ana noun
tains of the Truckee river plateau re-
gion, for twenty miles from an eleNa4
tion of about 5000 feet TO the sunni. SUN ~.
of the Sierra Nevadas at 1000 saddle OF
PASS elevation to about 5000 feet aver
age peak elevation; thence EXTENDING
westerly on mountain and foothfll slope
between the Middle Yuba and Bear
-ivers,. a distance of forty to forty,nVe
lilies to the lower foothill region alons
lie eastern edge of the sacramento val
ley at elevation OF 5OO 20 'oo leeS erDo1e AZ
sea level. Grass Valley ana NeNaud
Citv are at about the Typographical
center of this western area and from
their seat on the pine-clad mis- at
about $500 feet above sea level COM
mand a view of the snow-capped noun
tains in the direction of the rising sun
and at sunset glow catches the goloen
refeetion of the last setting rays on
the broad ribbon of the river waters
in the valley of the Sacramento.
croToGy OF MOUNTAIN AND VALLEY
East of the Sierra Nevada range the
geological surface presents a checker
- hn lava nnneS1te ana
basalt ridges and peaks, with the val
lev bottoms covered by bedding OF
claws and sands deposited by the eX-
tinct nlateau lakes or the glacial ana
later stream accumulations OF SAND anu anu
gravel, and the resulting fertile loaIns
and soils. Except on the steep weather.
worn easterly slope of the mountain
range no true bedrock formations are
exposed in the eastern end OF tne
coi,ntv and no veins or gold-Dearlhg
eravels have been found
westerly from the summit the Geol-
oev of the mountains. canyons dil1
hillsides presents a complex system OIL
generally north ana south ta. cou.St,s
belts of the earlier states or metamor-
nhosed sedimentary rocks, with alter-
hating belts, or extensive lentlcuiar
masses. and inclusions of the later lg-
neous rocks; consisting of serpentlne
diabase diorite and granite or granot
diorite, and the many altered lorlns
of these later rocks of the bed rock
series. Overlapping the pearocks IN
scattering areas diminishing as the
foothills are reached IS the flow of
rhvolite and it's andesite capplng
which have withstood the erosion OF
the waters and the raVages OF time
and the elements, and, as long sloplng
ridges between the present water
courses, or as bold rounded Knoll OF
rtn n q
unoent of the final age of the geologic
al restriction of the western plateau
and mountain regions.
THE OCCURRENCE OF VEINS
At the contacts with the states or
within the shear zones and shattered
areas associated with the igneous in
tr,1sions, and within the fissured areas
of the igneous masses occur the min
al-bearing quartz veins. The course
and dip of the veins vary throughout
all ranges of the compass and all de-
grees and direction of inclination, be
ing determined entirely by the lntu-
ence of contact, or proximity to con-
tact, and the system of cracking
iointing and blocking resulting from
The local geologic conditions and con-
seduent dynamic forces OF contraction
or pressure. In many districts, now
ever. there is decided tendency in the
stronger vein systems to parallel IN
strike and course the axis or the
mountain range and to dip Win m
cIination sleeper than the hill slope
away from the core of the mountain,
or toward the valleys at the west.
The granite or grano-diorites form
the last link in the formation of the
bedrock series of rocks and the quartz
veins were formed after this period.
The vein matter and mineral con-
tents of all of the veins are derived
from the magma or the later crystal
llzed mass of the igneous rocks, by
aqueous or gaseous agencies of alb
sorption, circulation and precipitation.
THE DEAD RIVER GRAND CHANNELS
Following the geologic period end
ing with the grano-diorite intrusion
and the assuring and deposition of the
mineral bearing veins the inner forces
of the mountain became inactive and
the power of glacier, of running stream
and the periodical climatic and exter-
nal agencies began the wear and tear
on the face of the bedrocks, breaking
down and wearing to cobbles and peb-
bles millions upon millions of cubic
yards of vein matter and country rock.
The conhguration of the western slope
of the Sierra Nevadas presented a
more uniform and more gently undu-
lating surface than today's rugged
canyons and ridges; and the valleys
through which the Pllocene rivers
flowed were broader and shallower.
The channels followed broad and
somewhat sinuous courses, and the
waters deposited in bedrock crevices
the suspended load of gold in nuggets,
cobbles and pebbles with gold in seams,
and the barren gravel and sands.
These channels became one long con-