The Weiser signal. [volume] (Weiser, Idaho) 1890-1904, 1900-03-22
THE GEOLOGICAL FORMATION
Observations and Researches of an Able Geol
ogist and Mining Engineer

Snake river canyon; all have slopes
of about 30 degrees angle from the
crest of the range to the river; and
all are about the same distance
three to five miles-away, in an air
line. from the river. their bases
touching it. Together they form a
som e w h a interrupted mountain
range, beginning near Huntington,
Ore, extending northward to the
mouth of the Salmon river, and run
ming nearly north and south. All
have highly metamorphosed and soft
schist of very early age as a ground,
work on the west, and granite on the
east: all have q more or less complete
basaltic cap which slopes gently to
the eastward. but does not extend to
the westward of the crest, to speak
of. forming the country from Middle
Valley to the Salmon river; all have
the basalt underlaid by vast areas of
granite, which extends eastward in
an almost continuous body through
Salmon meadows to the Sawtooth
range. All have bodies of porphyry
of various kinds, formed as intrud-
ING dykes, and which have been, at
least in part. the cause of the miner
alization. The basaltic flows have
run eastward in sheets, from north
and south assures many miles long,
arising near the crest of the range.
and have come out at successive in
tervals, forming layers of varying
thickness up to 5000 feet. Some OF
these flows are so recent that ho'
springs still exist near them Prob
ably none of them are earlier thar
the Tertiary. The same kind OF
sheet flows of basalt formed the
Snake plains between Boise and Pc
catello, and are peculiar to the Snake
river regions of Idaho, Oregon, anC
Washington. One of these flows
from the Eagle Valley mountains
filed up the valley of the Snake a
least 1000 feet deep, changed it
course. and compelled it to eat out
new channel cutting away the schis
along the eastern side of the basalt
which is now the Snake river can
Won. Another such flow from tn
northern end of the Seven Devils CT
off the lower six miles of the Rapi
river valley which then emptied IL
: to the Salmon river, and filled it u
some 5000 feet deep, forcing til
. river to cut its way eastward SON
: three miles till it emptied into tt
! Little Salmon, through the schis
4
: The damming of the Snake belo
Huntington formed a vast lake who's
limits extended far into Oregon an
= Southern Idaho, reached as far mort
as Council, Idaho, and extended cas-
q ward some distance beyond Bots
J., The shores of this lake were covert
!. with rank vegetation, composed
n forests of willow, cottonwood IN
pie. etc. The waters were still, al
:, deposited very much clay and SAL
I. in beds. and in places extensive are
t of tripoli and pipe clay. Many ho'
:. of basalt occurred while the lake e
Y listed, and probably few after t
5 Snake had cut its canyon and drain
9 lake The granite contactwith the SCH
d runs near the crest of the range a.
It little east of north, and with fe
% exceptions, is entirely barren of p
II mineral. Near this contact, howe
J. er, either in the granite or the schi
! are located all the large deposits
d pay ore, except the Vaughn, RiN
y Queen, etc.
d If we take single region it is
IS most impossible to discover the cal
J. of the naturalization but if we ia
1t all the districts together it is not d
d ficult to find cause, or causes.
y y find that nearly all the veins run e
"a of north; that they cannot be trat
ID for any great distance continuous
that all the ore and gangue occur