The Wallace miner. [volume] (Wallace, Idaho) 1907-current, 1913-06-12

the region where the formation occurs
The supposed equivalent of the Re.
vett quartzite is more micaceous and
thinner bedded here than In the type
locality and therefore less distinct
from the beds which are believed tc
represent the Burke formation.
The beds which are believed to rep.
resent the Newland (Wallace) forma
ltion are apparently much thicker thar
that formation In the Occur d'Alene
district and toward the southeast they
show a proportionately greater devel-
opment Of sandstones. The white and
gritty weathered surfaces of the sand
stones also generally show red and
yellow specks of iron oxides The
characteristic purplish bands of the st.
Regis formation are here lacking. The
strata representing the upper part of
the Newland (Wallace) and the Strip
ed Peak are like those formations in
the Occur d'Alene district, except that
the equivalents Of the Striped Peak
bench gravels are found mainly west
of Avery as shown on the map. In
addition there are a few very small
patches adjacent to the river above
Avery. These gravels lie on the base
level at $500 feet and are thought to
be equivalent in age to similar gravels
in the Prichard creek district and 9TH
err parts of the Occur d'Alene region.
In this area, however. they are not
gold bearing so far as known.
Horizons at Which Organic (?l Re-
mains Occur.
Forms suggestive of organic origin
We're found at two horizons in the beds
representing the Newland (Wallace)
formation. The lower horizon is about
1000 feet above that Of the Wishards
sill and the upper about 1000 feet
above this. On the summit of Quarles
peak the lower horizon is represented
by bed Of grayish limy shale about
three feet thick, crowded with flat
tened globular forms from half an
inch In diameter that suggest bivalves
Of some sort.
The localities at which observations
were made at the upper horizons are
three fourths Of mile southwest of
the summit of Quares peag and in
rock cuts along the line of the Chica-
go. Milwaukee & Puget Sound railway
about half mile below the Adair loop
and about 2 miles above the loop. At
these localities bed Of blush limy
shale or impure limestone contains
numerous flattened cylindrical forms
mashed trilobites DIR. Wal
colt has examined the specimens !
brought in from the field and states I
hat they ARE elongated, more or less
calcareous nodules. and /
some of them suggest organic origin ,
lgneous Rocks.
The gneiss intercalated with the !
'chists near the base of the section is
chiefly a gray, strongly Illuminated |
'oclx of medium coarse granular tex
ure modified by recrystallization UNI
Ter great pressure. The chief constit-
tents are soda-lime feldspar (oligo-
'lase), quartz. orthclase and micro
line much inferior in amount to the
'ligoclase, biotite and epidote, locally
With more or less hornblende.
In the southern part of r. 43 N. r. 4
g., is a large area of whitish rock con-
listing essentially of soda lime field
par with the average composition Of
abradorite. This anorthosite shows
o very conspicuous evidence of pres
ure except in local phases that con-
ain small amounts of hornblende and {
Their dark minerals which are drawn {
ut into streaks and give the rock
neissoid banding. Microscopic Sec
ions of the more purely feldspathic c
ariety, however, show 1t to have been
crushed and SHARED II :
as suffered, in fact, about the same a
mount of dynamic and metamorphism a
5 the gneiss above described.
Pegmatites that form numerous and ;
bikes and sheets in the t
neisses and schists of r. 43 N, r. 4 t.
:. consist chiefly of orthoclase and G
lartZ and most of them contain small
of mica and a-feldspar
heir most interesting feature is the
'eat variation in the amount of the
lartz. Gradations can be traced from
sgmatites with quartz subordinate to IT.
ldspar into those composed almost
holly of quartz; and 1t Is probable
at many quartz veins free from
ldspar In the area where pegmatites
e abundant are of magmatic origin
In the southern part Of the territory =,
amined are two areas of granitoid =,
ok evidently much younger than the :,
rongly foliated intrusive rocks de- -,
ribed. for while they OCCUR in close =,
oximity to these rocks, they are not ~
preciably sheared They presum- al
ly represent part of vast intru- E.
IN which occupies hundreds If sh
uare miles to the south and which sa
S probably caused the greater part Se
the contact metamorphism observed OF
nth of the st. Joe river. mi
The rocks Of the two areas are very Is
nilar and remarkably uniform They mi
of medium granular texture and re'
,sist essentially of plagioclasc (an- no
sine and oligoclase), subordinate or de
'clase. quartz and biotite, locally