The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1913-06-19
concluded from last week.

The most prominent structural fea-
ture Of. this area Is a large. open. fair
~ symetrlcal synclinc whose axis
trends about north Is degrees west.
The position Of its axis is shown by
small areas Of Striped peak formation
lying between Packsaddle synclne.
The trough involves an area roughly
. miles wide and 20 miles long end
ing to the southeast In canoe form
near Bird creek and to the northwest
In a somewhat similar manner.
Another fold that may be commen-
surate with the Packsaddle syncline
is an anticline shown by the plotted
dips south OF Lookout mountain In
township 43 north, Range n. There
was no opportunity to determine its
full extent. but it is known to persist
for at least miles II Is complicated
as the Marble creek section shows, by
minor folds and has an eastward pitch
which also characterixes the numerous
other less persistent folds In the
ined. Small compressed pitching folds
whose axes vary In trend but as
rule course west -northwest are char
acteristic Of the area lying between
st. Joe river and the most northeast
erly outcrops Of the Wishards sill, ex-
cept the portion occupied by the Pack
saddle syncline Except in small
fleyure trending northwest through
Wards peak the area northeast or the
sill outcrop mentioned exhibits mod
crate southwest dips only. On the
other hand northeast dips prevail IN
the area southwest Of the Packsaddle
syncline, hence the structure Of this
area as a whole may be defined as
that of northwestward- trending geo.
syncline succeeded to the south by an
apticline.
Faults.
Steeply inclined faults exhibiting
the dominant nortkwesterly trend are
numerous in the areas of complex fold
They are in many places but not every
where accompanied by thick breccias
The course OF St Joe river from Av-
cry up to Conrads seems to have ac-
commodated itself somewhat to zone
Of faults, some Of which have caused
considerable displacement. OF these,
the st. Joe fault, having downthrow
to the north Of at least 1900 feet
brings up the Wishards sill south of
the river and the Skookum fault drops
the blue shales which represent the
upper part of tho Newland (Wallace)
formation against the middle beds of
that formation. This fault is accom-
panied by breccia in places 900 feet
wide
There Is a great fault OF west-north-
west trend that follows the general
course of st. Joe river near the mouths
Of Marble end Mica creeks. It's down
throw is on the north and is great
enough to bring the strata represent
ing the Newland formation into close
proximity to the quartzites far down
in the Prichard
The distribution Of the rocks near
the boundary of TIPS. "A and As NJ, r..
f., is hardly explainable without
much faulting, but the exposures here
are so poor that 1t is doubtful whe-
Their the structure could ever be salts
factorily deciphered There Is strong
evidence Of the existence of a fault or
fanlt zone with downthrow to the
south following the general course of
Boulder creek. Brecciation has been
observed IN the quartztes both north
and south of that stream.
A great fault Of nearly north south
trend has been found in the southern
part Of the Fish Hook basin. Its
throw must amount to thousands of
feet. for II brings rocks representing
the Newand on the west against beds /