Deseret evening news. [volume] (Great Salt Lake City [Utah]) 1867-1920, 1900-03-14
THE MERITS OF
THE SEVEN DEVILS
Mineral, Heath and Seven Devils
District Compared.
FORMATION Is IDENTICAL.
Ore aud Gangue Occurs Ia Chutes-
GENERALIZATION Of Veins In Lines
Parallel With Granite Contact

Somewhat varied reports have been
circulated concerning the Seven Devils
country as coming mining center.
The following article dated from Wei
ser, and published by the Spokane
spokesman-Revlew may have some in
terest locally containing as 1t does
what appears to be good description
Of the formation OF the country. The
article Is as follows
When new mining district
comes into prominence the people on
the outside desire to know what is the
formation, In order in measure to
judge as 10 the probable outcome OF de-
velopment There has been for years
much contention as to the value Of the
mineral belt so pronounced In this,
Washington county, and many have
hell that its merit was ephemeral.
There has never been technical de-
scription Of II In print, so at this time,
moment are hning recorded. 10 briefly
exploit the formation Of the districts
with little reliable geological informa-
tlon OF reliable nature, may not come
IN amiss. There can be no separation OF
the mining districts OF the county, for
while they are wide apart they are an
integral portion Of the same range, and
OF practically the same meteorological
and geological conditions The range OF
mountains from a short distance north
Of Weser to the farthest end Of the
county take them all in beginning with
the Mineral district then the Heath
and then the Seven Devils.
The main features Of these three dis
tricts are Identical They are all on
the east side OF the Snake river, and
from II distant about four miles, with
their base along the stream, they have
angle slopes Of about 80 degrees, and to-
gether form the mountain chain re-
ferred and extending northwaTd to the
mouth Of the Salmon river, and extend
ing In north and south direction. The
formation on the west Is a metamor-
phosed mica schist as the groundwork
while on the east II is granite. Above
both Is a heavy layer of basalt, extend
ing 10 the east generally and forming
the country from Middle valley to the
Salmon river; while beneath the baEalt
comes a vast area Of granite which ex-
tends eastwards In almost a continu-
Gus body through the Salmon meadows
to the Sawtooth range All have bodies
OF porphyry Of various kinds formed as
intruding dykes and which have been at
least In part the cause OF the minerali-
zatlon. 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 ut successive intervals, form
ing layers OF various thickness up TO
5000 feet. Some Of these flows are so
recent that hot springs still exist near
them. Probably none OF them are ear
Her than the tertiary The same kind
Of sheet flows OF basalt formed the
Snake plains between Boise and Poca-
tello, and are peculiar 10 the Snake
river regions Of Idaho. Oregon and
Washington. One OF these flows from
the Eagle Valley mountains filed up
the valley Of the Snake at least 1900
feet deep. changing its course and COM
PEELED II 10 eat out new channel, cutt-
ing away the schist along the eastern
side OF the basalt, which Is now the
Snake river canyon.
Another such flow from the northern
end OF the Seven Devils cut OF the low
er six miles OF the Rapid river valley
which then emptied into the Salmon
river, and filled II up some 1000 feet
deep. forcing the river TO cut It's way
eastward some three miles till IL emp.
tied into the Little Salmon, through
the schist. The damming OF the Snake
below Huntington formed a vast lake,
whose limits extended far into Oregon
aud southern Idaho. reached as far
north as Council, Idaho, and EXTENDED
eastward some distance beyond Boise.
The shores Of this lake were covered
with rank vegetation composed Of for.
ests OF willows, c0ttonwoods, naples,
etc. the waters were still and deposited
very much clay and sand In beds and in
places extensive areas OF tripol. and
pipe clay Many flows Of basalt oc.
CURED while the lake existed. and
probably few after the Snake had
cut its canyon and so drained the lake.
The granite contact with the schlst
runs near the crest OF the range and
little east of north, and with few ex.
ceptions IL entirely barren Of pay min
eral. Near this contact, however.
either in the granite or the sohist, are
located all the large deposits OF pay
ore, except In the Vaughn, River Queen.
etc.
If single region Is taken II Is al
most impossible TO discover the cause
Of the naturalization, but Il we take all
the districts together II is not difficult
10 find cause, or 1auses. We find that
nearly all the veins run east OF north.
that they cannot be traced for any
great distance continuously, that all the
ore and gangue occurs in chutes
that outcrops OF porphyry can DE
traced for short distances only in the
vicinity OF some Of the leading mines.
entirely disappear farther on and again
crop up beyond. These facts In con-
necti0n with the character Of the gan
sue lead us 10 say that the mineraliza-
ton OF the veins In this region occurs In
lines parallel with the granite contact.
or In seres OF parallel veins, with occa-
sional cross veins, and that these veins
have been formed al different times and
by different agencies
There are two distinct series OF veins
In the schist-those parallel with the
granite contact and those interstratl-
fed with the schist. The latter are al
ways composed OF white quartz, are OF
varying thickness, rarely over four feet,
are as crooked as rams horns. and
faulted In all sorts Of ways They &C.
casionally carry gold in rich pockets OF
small sire. and are probably simple
cases Of inhltration. They never have
any porphyry with them. but often have
considerable micaclous iron. The North
Star at the head OF Rapid river Is one
OF these mines.
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