geologic map of the ophir creek 7.5' quadrangle, lewis and ...discontinuous zones of vitrophyre...
TRANSCRIPT
112°
30'
11
2° 3
7' 3
0"
112°
30'
112°
37'
30"
32' 3
0"
35'
32' 3
0"
35'
40'
40'
42' 3
0"
47' 3
0"
46°
37' 3
0"46
° 37
' 30"
46°
45'
46°
45'
T 12
NT
11 N
T 12
NT
11 N
T 11
NT
10 N
T 11
NT
10 N
R 8
W
R 7
W
R 8
W
R 7
W
50
5025
30
2830
40
5
35
15
913
6
23
14
15
30
15
10
20
2060
45
17
45
22
60
23
25
14
22
30
30
50
12
14
48
23
5835 34
33
40
65
50
55
80
38
40
30
38
11
1520
17
30
29
47
35
60
35
1870
18
2516
13
25
17
30
27
42
21
19
21
24
4045
Qgo
Qal
Trca
Tba
Qac
Trca
Trca
Qgr
Qgr
Qgr
Qgr
Qgr
Tba
Qgr
Trca
Qal
o
Trca
Qal
Qac
Qal
oTr
p
Tba
Tgr
Tba
Tba
Qgr
Trca
Qgr
Qls
Qgr
Trca
Trca
Tba
Trca
Trca
pl pl
Taf
Qgo
Trca
Qal
Qal
oTg
r
Qgr
Trca
Trca
Qal
o
MmKqm
Qgr
Qal
Qal
Qac
Qac
Kqm
Mm
Mm
Qal
o
pl plK
qm
pl plK
qmpl pl
pl pl
Trca
Qls
Trca
Qac
Qac
Mm
Taf
Tri
Qal
o
Kqm
P*Mps
Qgo
Qaf
Qls
Qal
o
Qgr
Ybo
Ybo
Kqm
Qgr
Qls
Taf
Taf
Ym
pl pl
_pm
Kqm
Taf
_pm
Mm
Qal
o
Qls
Qls
Taf
Qls
Qgt
Qls
Qls
Ybo
_wf
Dj
Qal
o
Trca
Qaf
Qaf
Qgt
Qgt
Taf
Taf
Taf
_pm
_wf
_pm
Qls
Qls
Taf
Qls
Qaf
Qls
Ybo
_m
Tri
Tri
Tri
_wf
Ym
Ym
s3
Taf
Taf
Ybo
Qgt
Ym
s3
Ym
Qgt
Taf
Ym
s2
Ym
s2
Ybo
Ym
s3
Ysh
Ysn
QmTrca
Qm
Qls
Trca
pl pl
pl pl
Trca
Qal
Qls
Qal
o Trca
Qls
Tba
Tri
pl pl
D_mp
D_mp
D_mp
D_mp
D_mp
D_mp
pl pl
pl pl
Qgt
Ym
s3
Trca
Qal
BLA
CK
FOO
T
CIT
Y
STO
CK
Black
Mountain
Syncline
A
A'
SC
ALE
: 1:2
4,00
0
feet
met
ers
010
0020
0030
00
010
0020
0030
0040
0050
0060
0070
0080
0090
0010
,000
Cro
ss S
ectio
n A
–A'
AA
' 2000
3000
4000
5000
6000
7000
8000
1000
2000 50
0
1500
2500
Elevation above sea level (meters)
Elevation above sea level (feet)
Ybo
Yms3
Yms2
Ysh
Tri
Taf
_wf
Ym
Ybo
Yms3
Yms2
Ysh
Ysn
Ym_wf
Ym
Ybo
Yms3
Yms2
Ysh
Ysn
Trca
Trca
Qgo
Qalo
Qgr
Taf
Ybo
Yms2Yms3
No
verti
cal e
xagg
erat
ion
Threemile Creek
3544
63 51
Strik
e an
d di
p of
incl
ined
bed
s
Faul
t: sh
ort-d
ashe
d w
here
infe
rred
, bar
and
bal
l on
dow
nthr
own
side
; arr
ows
indi
cate
mov
emen
t
Rev
erse
or t
hrus
t fau
lt: te
eth
on u
pthr
own
bloc
k; s
hort-
da
shed
whe
re in
ferr
ed; d
otte
d w
here
con
ceal
ed
Con
tact
: das
hed
whe
re a
ppro
xim
atel
y lo
cate
d
Strik
e an
d di
p of
cle
avag
e
Strik
e an
d di
p of
vol
cani
c fo
liatio
n
MA
P SY
MB
OLS
pl
Pla
cer w
orki
ngs
Syn
clin
e: s
how
ing
appr
oxim
atel
y lo
cate
d tra
ce o
f axi
al
plan
e an
d pl
unge
dire
ctio
n
Strik
e an
d di
p of
Bel
t Sup
ergr
oup
rock
s w
here
top
of
bedd
ing
is c
erta
in
Tgr
P*Mps
Pennsylvanian
Perm
ian
Mississippian
Devo
nian
Cambrian
Cretace
ous
Meso
proterozo
ic
Tertiary
Quaternary
Holoce
ne
Pleistoce
ne
CO
RR
ELAT
ION
DIA
GR
AM
Plioce
ne
Mioce
ne
Oligoce
ne
Eoce
ne
Qal
Qaf
Qgt
Taf
Tri
Trca
Trp
Qac
Qm
Qls
Qgr
Qgo
Qalo
Tba
Kqm
Dj
_pm
_wf
Ym
Ybo
Yms3
Yms2
Ysh
Ysn
Late
Cretace
ous
Mm
Bel
tS
uper
grou
p
D_mp
_m
? ?
? ?? ??
Geo
logi
c Su
mm
ary
Th
e no
rthea
ster
n th
ird o
f the
qua
dran
gle
is u
nder
lain
by
Mes
opro
tero
zoic
Bel
t Su
perg
roup
, Pal
eozo
ic se
dim
enta
ry ro
cks,
and
Cre
tace
ous t
o Eo
cene
igne
ous r
ocks
. Alth
ough
W
inst
on (1
986)
pro
pose
d th
at a
n ea
st–w
est M
esop
rote
rozo
ic d
own-
to-th
e-no
rth g
row
th fa
ult
trave
rsed
the
quad
rang
le, w
e sa
w n
o th
ickn
ess c
hang
es in
Bel
t Sup
ergr
oup
Form
atio
ns in
the
area
. The
sout
hwes
tern
2/3
of t
he m
ap is
und
erla
in b
y C
enoz
oic
volc
anic
and
sedi
men
tary
de
posi
ts o
f the
Avo
n Va
lley.
St
ruct
ure
is d
omin
ated
by
the
north
–nor
thw
est-t
rend
ing
Bla
ck M
ount
ain
sync
line
(Bie
rwag
en, 1
964)
and
nor
thw
est-s
triki
ng th
rust
and
nor
mal
faul
ts. N
orth
east
-stri
king
hig
h-an
gle
faul
ts c
ut th
e no
rthw
est s
truct
ures
. The
thru
st fa
ults
and
the
Bla
ck M
ount
ain
sync
line
may
be
kine
mat
ical
ly li
nked
; the
sync
line’
s age
is b
rack
eted
by
the
youn
gest
rock
s tha
t are
invo
lved
in
the
fold
ing
and
by th
e cr
oss-
cutti
ng B
lack
foot
City
stoc
k, a
nd is
ther
efor
e in
ferr
ed to
be
77–9
7 M
a (S
chm
idt a
nd o
ther
s, 19
94).
The
north
wes
t-tre
ndin
g, c
ontra
ctio
nal s
truct
ures
incl
udin
g th
is
fold
, and
the
reve
rse
faul
ts, a
re p
ostu
late
d to
be
part
of th
e Le
wis
and
Cla
rk L
ine,
a si
nist
ral
trans
pres
sive
stru
ctur
e th
at fo
rmed
sync
hron
ousl
y w
ith S
evie
r thr
ustin
g du
ring
the
Cre
tace
ous
that
was
late
r rea
ctiv
ated
dur
ing
Terti
ary
exte
nsio
n (S
ears
and
Hen
drix
, 200
4). N
orth
wes
t- st
rikin
g, d
own-
to-th
e-so
uthw
est,
norm
al fa
ults
con
trol m
uch
of th
e no
rthea
st si
de o
f the
Ter
tiary
Av
on V
alle
y. T
hey
form
ed p
aral
lel t
o th
e co
ntra
ctio
nal s
truct
ures
. Rel
ativ
ely
min
or
north
east
-stri
king
, hig
h-an
gle
faul
ts a
ppea
r to
cut a
ll th
e ot
her s
truct
ures
.
Lo
en (1
990)
des
crib
ed fo
ur ty
pes o
f Ter
tiary
dep
osits
: Plio
cene
(?) p
edim
ent g
rave
l, M
ioce
ne(?
) fan
glom
erat
e, M
ioce
ne (?
) silt
ston
e an
d sa
ndst
one,
and
Olig
ocen
e B
lack
foot
City
be
ds. O
n th
e cu
rren
t Oph
ir C
reek
qua
dran
gle
thes
e de
posi
ts a
re sh
own
resp
ectiv
ely
as G
rave
l (Ts)
, Allu
vial
-fan
dep
osit
(Taf),
Ren
ova
Form
atio
n—A
ntel
ope
Hill
mem
ber (Trah
), an
d R
enov
a Fo
rmat
ion—
Clim
bing
Arr
ow M
embe
r (Trca
).
Des
crip
tion
of M
ap U
nits
Qal
A
lluvi
um (Q
uate
rnar
y: H
oloc
ene)
—G
rave
l, sa
nd, s
ilt, a
nd c
lay
alon
g st
ream
s and
thei
r tri
buta
ries.
Cla
sts g
ener
ally
roun
ded
to su
brou
nded
cob
ble
size
and
smal
ler,
but
boul
ders
als
o pr
esen
t.
Qaf
A
lluvi
al-f
an d
epos
it (Q
uate
rnar
y: H
oloc
ene)
—G
rave
l, sa
nd, s
ilt, a
nd c
lay
in d
epos
it w
ith fa
n-sh
aped
mor
phol
ogy
near
Thr
eem
ile C
reek
and
alo
ng B
alla
rat C
reek
, bot
h on
th
e w
este
rn si
de o
f the
map
are
a. C
last
s prim
arily
der
ived
from
Qgt a
nd Taf.
Qac
A
lluvi
um a
nd c
ollu
vium
(Qua
tern
ary:
Hol
ocen
e)—
Silt,
sand
, gra
nule
s, an
d pe
bble
s de
posi
ted
on sl
opes
by
shee
twas
h al
luvi
um in
corp
orat
ed w
ith lo
cally
der
ived
fin
e-gr
aine
d co
lluvi
um.
Qm
M
antle
(Qua
tern
ary:
Hol
ocen
e an
d Pl
eist
ocen
e)—
Dep
osit
that
incl
udes
shee
twas
h al
luvi
um, c
ollu
vium
, coa
rse-
grai
ned
(peb
ble,
cob
ble,
smal
l bou
lder
) lag
from
old
er
depo
sits
, and
rego
lith.
Qls
L
ands
lide
depo
sit (
Qua
tern
ary:
Hol
ocen
e or
Ple
isto
cene
)—M
ass-
was
ting
depo
sit o
f ro
tate
d or
cha
otic
bed
s tha
t slid
dow
nslo
pe. T
he b
ento
nitic
Clim
bing
Arr
ow M
embe
r an
d un
its th
at im
med
iate
ly o
verli
e it
are
parti
cula
rly p
rone
to d
evel
opin
g la
ndsl
ide
depo
sits
.
Qgr
G
rave
l (Q
uate
rnar
y: P
leis
toce
ne)—
Dep
osits
rew
orke
d fr
om Taf a
nd Q
go
on
slop
es
belo
w th
e so
urce
dep
osits
.
Qal
o A
lluvi
um, o
lder
than
Qal
(Qua
tern
ary:
Ple
isto
cene
)—D
epos
its in
bro
ad v
alle
ys w
ith
unde
rfit
stre
ams.
Cla
sts l
ocal
ly d
eriv
ed.
Qgt
G
laci
al ti
ll (Q
uate
rnar
y: P
leis
toce
ne)—
Poor
ly so
rted,
suba
ngul
ar to
subr
ound
ed
gran
ules
, peb
bles
, cob
bles
, and
bou
lder
s in
a sa
ndy
to lo
cally
cla
yey
mat
rix. I
nclu
des
boul
ders
as m
uch
as 3
m (1
0 ft)
in d
iam
eter
, dom
inan
tly o
f qua
rtzite
and
lim
esto
ne.
Qgo
G
laci
al o
utw
ash
(Qua
tern
ary:
Ple
isto
cene
)—D
epos
its a
long
Six
mile
Cre
ek th
at
repr
esen
t the
term
inus
of a
larg
e gl
acia
l out
was
h fa
n th
at c
ontin
ues i
nto
the
Gra
vely
M
ount
ain
7.5'
qua
dran
gle
to th
e w
est.
Fan
is a
bout
6.5
km
(4 m
i) lo
ng. R
ewor
ked,
su
brou
nded
, iro
n-st
aine
d pe
bble
s and
cob
bles
that
are
dom
inan
tly c
last
-sup
porte
d.
Tgr
Gra
vel d
epos
it (T
ertia
ry: P
lioce
ne)—
Poor
ly to
wel
l-stra
tifie
d bo
ulde
r, an
d pe
bble
-cob
ble
grav
el, s
and,
silt,
and
cla
y. In
clud
es so
me
lag
depo
sits
. Loc
ally
con
tain
s pl
acer
gol
d. A
fter L
oen,
199
0.
Taf
Allu
vial
-fan
dep
osit
(Ter
tiary
)—D
omin
antly
mat
rix-s
uppo
rted,
but
loca
lly c
last
- su
ppor
ted
depo
sit t
hat o
ccur
s prim
arily
adj
acen
t to
rang
e-fr
ont f
ault.
Cla
sts r
ange
from
pe
bble
to la
rge
boul
der s
ize
in c
lay/
silt/
sand
mat
rix. C
last
com
posi
tion
dom
inan
tly
Bel
t Sup
ergr
oup
quar
tzite
with
subo
rdin
ate
Pale
ozoi
c, v
olca
nic,
and
plu
toni
c ro
ck.
Incl
udes
loca
l ext
rem
ely
larg
e bo
ulde
rs. S
ome
smal
l are
as sh
own
as P
aleo
zoic
out
crop
w
ithin
the
fan
depo
sits
on
prev
ious
map
s are
inte
rpre
ted
as b
urie
d bo
ulde
rs. D
epos
it ha
s pre
viou
sly
been
inte
rpre
ted
as M
ioce
ne(?
) (Lo
en, 1
990;
Sch
mid
t and
oth
ers,
1994
) bu
t may
be
as o
ld a
s Eoc
ene
base
d on
inte
rfin
gerin
g re
latio
nshi
p w
ith C
limbi
ng A
rrow
Fo
rmat
ion
prim
arily
obs
erve
d in
Fin
n 7.
5' q
uadr
angl
e to
the
north
. Dep
osit
cont
ains
pl
acer
gol
d (L
oen,
199
0). M
ay b
e as
thic
k as
300
m (9
85 ft
).
Tba
Bas
alt (
Tert
iary
: ear
ly O
ligoc
ene
or la
te E
ocen
e?)—
Bla
ck to
dar
k re
ddis
h br
own
mas
sive
flow
s tha
t wea
ther
yel
low
ish
red
to y
ello
wis
h br
own.
Flo
w to
ps v
esic
ular
w
ith c
aviti
es st
retc
hed
para
llel t
o flo
w d
irect
ion.
As m
uch
as 3
0% o
f the
ves
icle
s are
fil
led
with
cha
lced
ony
and/
or c
alci
te. R
ange
s mic
rosc
opic
ally
from
aph
aniti
c to
sl
ight
ly p
orph
yriti
c. A
ugite
and
pla
gioc
lase
phe
nocr
ysts
1–5
mm
(0.0
4 to
0.2
0 in
) lon
g oc
cur i
n a
pilo
taxi
tic m
atrix
of s
ubor
ient
ed p
lagi
ocla
se la
ths.
Acc
esso
ry m
iner
als
incl
ude
biot
ite a
nd ti
tano
mag
netit
e or
ilm
enite
. Sec
onda
ry m
iner
als i
nclu
de h
emat
ite
and
epid
ote.
Afte
r Loe
n, 1
990.
Trca
R
enov
a Fo
rmat
ion:
Clim
bing
Arr
ow M
embe
r (T
ertia
ry: E
ocen
e)—
Pale
oliv
e, li
ght
oliv
e gr
ay, m
oder
ate
oliv
e br
own,
and
med
ium
ligh
t gra
y, b
ento
nitic
mud
ston
e an
d ye
llow
ish
gray
silts
tone
. Con
tain
s len
ses o
f bro
wni
sh g
ray
sand
ston
e, a
nd
grav
el/c
ongl
omer
ate
usua
lly w
ith p
ebbl
e-si
ze c
last
s dom
inat
ing
the
coar
ser c
last
s in
a sa
nd/g
ranu
le m
atrix
. San
dsto
ne d
omin
antly
med
ium
- to
coar
se-g
rain
ed.
Gra
vel/c
ongl
omer
ate
cons
ists
of c
last
-sup
porte
d le
nses
of r
ound
ed g
ranu
les,
pebb
les,
and
cobb
les o
f rhy
olite
por
phyr
y an
d ot
her d
omin
antly
vol
cani
c lit
holo
gies
in a
sand
y m
atrix
. Uni
t typ
ical
ly d
ispl
ays “
popc
orn”
wea
ther
ing,
larg
e de
sicc
atio
n cr
acks
, and
is
pron
e to
land
slid
e de
velo
pmen
t. Ex
pose
d th
ickn
ess a
ppro
xim
atel
y 90
m (3
00 ft
).
Tri
Rhy
olite
plu
gs a
nd d
ikes
(Ter
tiary
: lat
e E
ocen
e?)—
Ligh
t gra
y to
ligh
t bro
wn,
no
n-fo
liate
d, p
orph
yriti
c, w
ith 1
0–40
% p
heno
crys
ts o
f san
idin
e an
d qu
artz
. Dik
es a
t Eu
reka
Gul
ch a
re m
iner
aliz
ed a
nd o
ccur
in th
e so
urce
are
a fo
r pro
duct
ive
gold
pla
cers
. A
cces
sory
min
eral
s inc
lude
iron
oxi
des a
nd a
patit
e. D
ikes
in T
iger
Gul
ch c
onta
in
anhe
dral
sani
dine
and
qua
rtz p
heno
crys
ts 1
–6 m
m (0
.04–
0.24
in) l
ong
in a
fin
e-gr
aine
d m
atrix
of f
elds
par a
nd c
lay,
and
are
typi
cally
hyd
roth
erm
ally
alte
red.
D
ump
spec
imen
s at T
ier G
ulch
are
inte
nsel
y si
licifi
ed. I
ntru
sive
rhyo
lite
in th
e m
ount
ain
area
is h
ydro
ther
mal
ly a
ltere
d an
d co
mm
only
con
tain
s dis
sem
inat
ed p
yrite
. A
fter L
oen,
199
0.
Trp
Rhy
olite
por
phyr
y (T
ertia
ry: E
ocen
e)—
Porp
hyrit
ic rh
yolit
e la
va fl
ows a
re ty
pica
lly
gray
, whi
te, t
an, r
ed, a
nd/o
r pur
ple
wea
ther
ing.
Cen
timet
er- t
o m
eter
-sca
le fl
ow
folia
tions
giv
e rh
yolit
e ou
tcro
ps a
blo
cky
wea
ther
ing
char
acte
ristic
. Phe
nocr
ysts
co
mpo
se u
p to
30%
of t
he ro
ck a
nd in
clud
e qu
artz
, san
idin
e, o
ligoc
lase
, bio
tite,
and
am
phib
ole
in a
mat
rix o
f gla
ss, c
lay,
and
cry
ptoc
ryst
allin
e m
ater
ial.
Dev
itrifi
catio
n of
th
e m
atrix
var
ies f
rom
non
e to
com
plet
e. L
ithop
hysa
e up
to 1
0 ce
ntim
eter
s in
diam
eter
ar
e lo
cally
abu
ndan
t and
typi
cally
ero
ded
and
parti
ally
fille
d w
ith c
halc
edon
y.
Dis
cont
inuo
us z
ones
of v
itrop
hyre
and
aut
obre
ccia
sepa
rate
indi
vidu
al fl
ows.
Kqm
Q
uart
z m
onzo
nite
of t
he B
lack
foot
City
stoc
k (U
pper
Cre
tace
ous)
—M
ediu
m-
grai
ned,
hyp
idio
mor
phic
gra
nula
r, eq
uigr
anul
ar, a
nd p
orph
yriti
c, b
iotit
e-ho
rnbl
ende
m
onzo
nite
, qua
rtz m
onzo
nite
, and
gra
nodi
orite
. Com
posi
tion
45%
pla
gioc
lase
, 8–2
0%
pota
ssiu
m fe
ldsp
ar, 1
6–25
% q
uartz
, 8–1
0% h
ornb
lend
e, 4
–7%
bio
tite.
Por
phyr
itic
and
folia
ted
near
con
tact
s. B
iotit
e yi
elde
d a
K-A
r age
of 7
7 M
a. A
fter S
chm
idt a
nd o
ther
s, 19
94.
P*M
Ph
osph
oria
and
Qua
dran
t For
mat
ions
, and
Sno
wcr
est R
ange
Gro
up, u
ndiv
ided
(P
erm
ian
thro
ugh
Upp
er M
issi
ssip
pian
)
Ph
osph
oria
For
mat
ion
(Per
mia
n)—
Gra
y fin
e- to
med
ium
-gra
ined
qua
rtz a
reni
te a
t to
p, g
ray
to p
ale
brow
n, th
inly
inte
rbed
ded
oolit
ic, p
hosp
hatic
sand
ston
e, sh
ale,
and
ch
ert i
n th
e m
iddl
e, a
nd y
ello
wis
h lim
esto
ne, c
herty
lim
esto
ne, s
iltst
one,
and
qua
rtz
aren
ite a
t bot
tom
. Thi
ckne
ss a
bout
50
m (1
60 ft
).
Q
uadr
ant F
orm
atio
n (P
enns
ylva
nian
)—G
ray
to ta
n, th
ick-
bedd
ed, v
itreo
us,
fine-
grai
ned
quar
tzite
. Thi
ckne
ss 4
5 m
(145
ft).
Afte
r Sch
mid
t and
oth
ers,
1994
.
Sn
owcr
est R
ange
Gro
up (L
ower
Pen
nsyl
vani
an to
Upp
er M
issi
ssip
pian
)—R
ed,
purp
le, g
ray,
and
tan
shal
e an
d si
ltsto
ne w
ith in
terb
edde
d re
d, y
ello
w, a
nd g
ray
limes
tone
and
dol
omite
. Abo
ut 4
0 m
(130
ft) t
hick
. Afte
r Sch
mid
t and
oth
ers,
1994
.
Mm
M
adis
on G
roup
(Upp
er a
nd L
ower
Mis
siss
ippi
an)—
Upp
er p
art i
s gra
y, m
assi
ve
bios
parit
e, b
iom
icrit
e, a
nd m
icrit
e. L
ower
par
t is t
hin-
bedd
ed g
ray
limes
tone
that
co
ntai
ns sc
atte
red
dark
gra
y, b
lack
, and
bro
wn
cher
t nod
ules
and
lens
es. T
hick
ness
450
m
(1,4
60 ft
). A
fter S
chm
idt a
nd o
ther
s, 19
94.
Dj
Jeff
erso
n Fo
rmat
ion
(Upp
er D
evon
ian)
—G
ray
to b
lack
, thi
ck-b
edde
d, c
oars
ely
crys
talli
ne, f
etid
dol
omite
with
thin
inte
rbed
s of l
ight
gra
y lim
esto
ne. T
hick
ness
230
m
(750
ft).
Afte
r Sch
mid
t and
oth
ers,
1994
.
D_m
M
ayw
ood,
Red
Lio
n, a
nd P
ilgri
m F
orm
atio
ns, u
ndiv
ided
(Upp
er D
evon
ian
to U
pper
C
ambr
ian)
May
woo
d Fo
rmat
ion
(Upp
er D
evon
ian)
—R
ed, g
ray,
and
gra
yish
gre
en sh
ale,
si
ltsto
ne, l
imes
tone
, and
dol
omite
. App
roxi
mat
ely
10 m
(30
ft) th
ick.
Afte
r Sch
mid
t an
d ot
hers
, 199
4.R
ed L
ion
Form
atio
n (U
pper
Cam
bria
n)—
Ligh
t gra
y m
ediu
m- t
o th
in-b
edde
d co
ntai
ning
thin
inte
rbed
s of o
rang
e an
d re
d w
eath
erin
g si
liceo
us a
nd a
rgill
aceo
us
dolo
mite
. Abo
ut 1
00 m
(325
ft) t
hick
. Afte
r Sch
mid
t and
oth
ers,
1994
.Pi
lgri
m F
orm
atio
n (U
pper
Cam
bria
n)—
Ligh
t gra
y, m
assi
ve to
thin
ly la
min
ated
, fin
ely
crys
talli
ne a
nd m
icro
crys
talli
ne d
olom
ite. A
bout
185
m (6
00 ft
) thi
ck. A
fter
Schm
idt a
nd o
ther
s, 19
94.
_pm
Pa
rk a
nd M
eagh
er F
orm
atio
ns, u
ndiv
ided
(Mid
dle
Cam
bria
n)Pa
rk F
orm
atio
n (M
iddl
e C
ambr
ian)
—G
rayi
sh g
reen
fiss
ile, w
axy
shal
e an
d in
terb
edde
d si
ltsto
ne a
nd g
ray
limes
tone
. Ver
y po
orly
exp
osed
. App
roxi
mat
ely
80 m
(2
60 ft
) thi
ck. A
fter S
chm
idt a
nd o
ther
s, 19
94.
Mea
gher
For
mat
ion
(Mid
dle
Cam
bria
n)—
Gra
y th
in- t
o th
ick-
bedd
ed m
icrit
e an
d bi
omic
rite
cont
aini
ng d
istin
ctiv
e th
in in
terb
eds o
f une
ven
and
disc
ontin
uous
gol
d an
d or
ange
wea
ther
ing
silic
eous
and
arg
illac
eous
dol
omite
. Thi
ckne
ss a
ppro
xim
atel
y 18
0 m
(590
ft).
Afte
r Sch
mid
t and
oth
ers,
1994
.
_wf
Wol
sey
and
Flat
head
For
mat
ions
, und
ivid
ed (M
iddl
e C
ambr
ian)
Wol
sey
Form
atio
n (M
iddl
e C
ambr
ian)
—G
reen
ish
gray
mic
aceo
us sh
ale
and
glau
coni
tic si
ltsto
ne in
terb
edde
d w
ith th
in b
eds o
f gra
y lim
esto
ne n
ear t
he to
p an
d w
ith g
lauc
oniti
c qu
artz
ite n
ear t
he b
ase.
Ver
y po
orly
exp
osed
. Thi
ckne
ss
appr
oxim
atel
y 90
–120
m (2
95–3
90 ft
). A
fter S
chm
idt a
nd o
ther
s, 19
94.
Flat
head
For
mat
ion
(Mid
dle
Cam
bria
n)—
Gra
y to
pur
ple,
thin
- to
thic
k-be
dded
fin
e- to
med
ium
-gra
ined
to c
ongl
omer
atic
, cro
ssbe
dded
qua
rtz a
reni
te. C
onta
ins
com
mon
wel
l-rou
nded
coa
rse
quar
tz g
rain
s. Th
ickn
ess 0
–30
m (0
–100
ft).
Afte
r Sc
hmid
t and
oth
ers,
1994
.
Ym
M
cNam
ara
Form
atio
n (M
esop
rote
rozo
ic)—
Cou
plet
s and
mic
roco
uple
ts o
f var
iega
ted
red
and
gree
n fin
e-gr
aine
d qu
artz
ite, s
iltite
, and
wax
y ar
gilli
te c
onta
inin
g di
agno
stic
re
d or
gre
en c
hert
beds
and
che
rt rip
-up
clas
ts. M
ud c
rack
s and
mud
rip-
up c
last
s co
mm
on. T
op p
art i
s lig
ht g
ray,
thic
k-be
dded
, fin
e- to
med
ium
-gra
ined
, cro
ssbe
dded
qu
artz
ite c
onta
inin
g ab
unda
nt re
d m
ud ri
p-up
cla
sts,
unco
mm
on re
d ch
ert r
ip-u
p cl
asts
, and
abu
ndan
t thi
n, re
d, m
ud c
rack
ed a
rgill
ite in
terb
eds.
Abo
ut 7
70 m
(2,5
00 ft
) th
ick.
Ybo
B
onne
r Fo
rmat
ion
(Mes
opro
tero
zoic
)—Pi
nk to
red,
med
ium
- to
coar
se-g
rain
ed, p
oorly
so
rted,
ver
y fe
ldsp
athi
c qu
artz
ite. A
bund
ant t
roug
h an
d pl
anar
cro
ssbe
ds in
bed
s ty
pica
lly 0
.5–1
.0 m
thic
k. B
eds o
ften
sepa
rate
d by
thin
(0.1
–1.0
cm
) red
to m
aroo
n ar
gilli
te b
eds.
Con
tain
s abu
ndan
t wel
l-rou
nded
coa
rse
quar
tz g
rain
s, an
d sp
arse
su
bang
ular
gra
nule
s and
smal
l peb
bles
. Fiv
e sl
abbe
d an
d st
aine
d sa
mpl
es c
onta
ined
50
–75
perc
ent q
uartz
, 15–
35 p
erce
nt p
otas
sium
feld
spar
, and
5–1
5 pe
rcen
t pl
agio
clas
e. P
oorly
exp
osed
con
tact
s mak
e th
ickn
ess e
stim
ates
pro
blem
atic
, but
are
re
porte
d to
be
460
m (1
,495
ft) t
hick
in th
is a
rea
(Sch
mid
t and
oth
ers,
1994
).
Ym
s3
Mou
nt S
hiel
ds F
orm
atio
n, m
embe
r 3
(Mes
opro
tero
zoic
)—R
ed q
uartz
ite to
arg
illite
co
uple
s and
cou
plet
s with
abu
ndan
t mud
cra
cks,
mud
chi
ps, a
nd d
iagn
ostic
, w
ell-f
orm
ed c
ubic
salt
cast
s. In
clud
es g
reen
inte
rbed
s and
som
e re
d m
icro
lam
inae
. A
bout
275
m (9
00 ft
) thi
ck o
n th
e no
rth-a
djac
ent N
evad
a M
ount
ain
7.5'
qua
dran
gle
(McD
onal
d an
d Lo
nn, 2
015)
.
Ym
s2
Mou
nt S
hiel
ds F
orm
atio
n, m
embe
r 2
(Mes
opro
tero
zoic
)—Pi
nk to
red,
poo
rly so
rted,
m
ediu
m- t
o co
arse
-gra
ined
, fel
dspa
thic
qua
rtzite
. Abu
ndan
t pla
nar a
nd tr
ough
cr
ossb
eds.
Con
tain
s spa
rse
suba
ngul
ar g
ranu
les.
Low
er p
art i
s thi
nner
bed
ded,
co
nsis
ting
of c
oupl
es o
f whi
te to
pin
k, m
ediu
m-g
rain
ed q
uartz
ite a
nd th
in re
d ar
gilli
te
that
con
tain
abu
ndan
t red
mud
chi
ps a
t the
bas
es o
f the
qua
rtzite
bed
s and
was
in
clud
ed in
the
top
part
of m
embe
r 1 o
f Sch
mid
t and
oth
ers (
1994
). In
con
trast
to
Bon
ner F
orm
atio
n, w
hich
has
pot
assi
um fe
ldsp
ar in
exc
ess o
f pla
gioc
lase
, tw
o sl
abbe
d an
d st
aine
d sa
mpl
es c
onta
ined
65–
75 p
erce
nt q
uartz
, 5–1
5 pe
rcen
t pot
assi
um
feld
spar
, and
20
perc
ent p
lagi
ocla
se. V
ery
diffi
cult
to d
istin
guis
h in
the
field
and
in
hand
sam
ple
from
the
Bon
ner F
orm
atio
n (u
nit Y
bo
). Th
ickn
ess a
ppro
xim
atel
y 46
0 m
(1
,500
ft).
Ysh
Sh
epar
d Fo
rmat
ion
(Mes
opro
tero
zoic
)—D
olom
itic
and
non-
dolo
miti
c, d
ark
gree
n si
ltite
and
ligh
t gre
en a
rgill
ite in
mic
rola
min
ae a
nd c
oupl
ets o
f non
-dol
omiti
c re
d qu
artz
ite to
arg
illite
. Poo
rly e
xpos
ed, b
ut w
eath
ers i
nto
thin
pla
tes t
hat w
hen
dolo
miti
c ha
ve a
cha
ract
eris
tic o
rang
ish
brow
n w
eath
erin
g rin
d. R
ippl
es a
nd lo
ad
cast
s are
com
mon
; mud
cra
cks a
re ra
re. T
he u
pper
hal
f con
tain
s int
erva
ls o
f pin
k to
gr
ay fi
ne-g
rain
ed fe
ldsp
athi
c qu
artz
ite th
at w
ere
incl
uded
in M
ount
Shi
elds
mem
ber 1
by
Sch
mid
t and
oth
ers (
1994
). H
owev
er, w
e pl
ace
the
uppe
r con
tact
at t
he to
p of
a 5
0 m
(160
ft) t
hick
inte
rval
of d
istin
ctiv
e ro
se-c
olor
ed d
olom
itic
silti
te–a
rgill
ite c
oupl
ets
as w
as d
one
in a
reas
to th
e w
est (
Lonn
and
oth
ers,
2010
). Th
e lo
wer
con
tact
is p
lace
d at
the
botto
m o
f the
low
est d
olom
ite-b
earin
g be
ds, a
lthou
gh in
are
as to
the
wes
t the
Sn
owsl
ip F
orm
atio
n al
so c
onta
ins d
olom
ite-b
earin
g in
terv
als (
Lonn
and
oth
ers,
2010
). A
cal
citic
stro
mat
olite
bed
is ty
pica
lly fo
und
near
the
base
. Thi
ckne
ss is
abo
ut
650
m (2
,100
ft),
sim
ilar t
o th
at in
the A
ustin
7.5
' qua
dran
gle
to th
e ea
st (B
erg
and
Lonn
, 201
1).
Ysn
Sn
owsl
ip F
orm
atio
n (M
esop
rote
rozo
ic)—
Inte
rbed
ded
inte
rval
s of q
uartz
ite to
red
argi
llite
cou
plet
s, an
d da
rk g
reen
silti
te to
ligh
t gre
en a
rgill
ite c
oupl
ets a
nd
mic
rola
min
ae. D
esic
catio
n cr
acks
and
mud
rip-
up c
last
s are
com
mon
thro
ugho
ut.
Arg
illite
bed
s ofte
n co
ntai
n irr
egul
ar “
bum
ps”
that
may
be
ill-d
efin
ed sa
lt ca
sts o
r st
ruct
ures
rela
ted
to a
lgal
mat
s. C
onta
ins b
eds a
nd le
nses
of d
istin
ctiv
e w
hite
, co
arse
-gra
ined
, wel
l-sor
ted,
feld
spar
-poo
r qua
rtzite
that
con
tain
s som
e w
ell-r
ound
ed,
fros
ted
quar
tz g
rain
s. Lo
wer
50
m (1
60 ft
) dom
inat
ed b
y m
icro
lam
inat
ed g
reen
do
lom
itic
silti
te a
nd a
rgill
ite. U
pper
50–
75 m
(160
–245
ft) i
s red
, fla
t-lam
inat
ed
med
ium
-gra
ined
qua
rtzite
in b
eds 0
.5–1
.0 m
eter
s thi
ck. T
hick
ness
app
roxi
mat
ely
1,07
5 m
(3,5
00 ft
) on
the
north
-adj
acen
t Nev
ada
Mou
ntai
n qu
adra
ngle
(McD
onal
d an
d Lo
nn, 2
015)
.
Ref
eren
ces
Ber
g, R
.B.,
and
Lonn
, J.D
., 20
11, G
eolo
gic
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he A
ustin
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dran
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cen
tral M
onta
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Mon
tana
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eau
of M
ines
and
Geo
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t 603
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and
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er g
old
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sits
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e O
phir
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trict
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ell,
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nd
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rk C
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ies,
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a Ea
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dran
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wes
tern
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tana
: Mon
tana
Bur
eau
of M
ines
and
Geo
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ada
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n an
d G
rani
te B
utte
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adra
ngle
s, w
est-c
entra
l Mon
tana
: Mon
tana
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of M
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and
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logy
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pen-
File
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ort 6
65, s
cale
1:2
4,00
0.*S
chm
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R.G
., Lo
en, J
.S.,
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lace
, C.A
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d M
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he E
llist
on
regi
on, P
owel
l, an
d Le
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and
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rk C
ount
ies,
Mon
tana
: U.S
. Geo
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cal S
urve
y B
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tin 2
45, 2
5 p.
, sca
le 1
:62,
500.
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s, J.W
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d H
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ix, M
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04, L
ewis
and
Cla
rk L
ine
and
the
rota
tiona
l orig
in o
f the
Alb
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an
d H
elen
a sa
lient
s, N
orth
Am
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ordi
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, A.J.
, and
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urva
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Win
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, Don
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6, S
edim
enta
tion
and
tect
onic
s of t
he M
iddl
e Pr
oter
ozoi
c B
elt B
asin
, and
thei
r in
fluen
ce o
n Ph
aner
ozoi
c co
mpr
essi
on a
nd e
xten
sion
in w
este
rn M
onta
na a
nd
north
ern
Idah
o, in
Pet
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n, J.
A.,
ed.,
Pale
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cs a
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edim
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ain
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ion,
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ted
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es: A
mer
ican
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ocia
tion
of P
etro
leum
Geo
logi
sts
Mem
oir 4
1, p
. 87–
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201
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MG
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ount
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