Ramsey 

Mtn

 COPPER

QUEEN

MINE

Yac Yac

Yac

Pp

Yg

Ms

Yac

Mm

Tc

Mm

Yg

Tc

PMs

Yg

Tc Tsu

Yac

Pp

Tsu

Yg

PMs

Mm Mm

Zc

Ms

Ys

Yg

Ms

Yg

Ms

PMs

Yg

Qls

Ms Og

Ms

Yg

Qls

Tsu

PMs

Qls

Qt

Qa

Qls

Ys

Qa

Mm

Qls

Mr

SOs

Zw

Qa

Tc

Qa Qa

Qt Qt

Yg

Qls Qa Yg Qa

Ok

Ms Mr

Mr PMs

Yac Yac

Yac

Yg

PMs

GOAT MOUNTAIN–

BLACK CANYON

FAULT SYSTEM

LITTLE EIGHTMILE

FAULT SYSTEM

JAKES CANYON

THRUST FAULT

RAILROAD CANYON

FAULT

BABY JOE GULCH

THRUST FAULT

SYSTEM THOMPSON GULCH

THRUST FAULT

THRUST DUPLEX

Lemhi River

Yearian Creek

North Fork Yearian Creek

Reese Creek

Left Fork Peterson Creek

Right Fork Peterson Creek

West Fork Little Eightmile Creek

Little Eightmile Creek

Canyon Creek

Salt Creek

Salt Creek

LITTLE DRY GULCH NAPO CANYON

RAMSEY MOUNTAIN

JAKES CANYON

RAILROAD CANYON

SECTION

A-A'

SECTION

B-B'

SECTION

D-D'

D'

EAST

METERS

5,000

4,000

3,000

6,000

7,000

8,000

9,000

10,000

D

WEST

FEET

Tc

Ms Tsu

Qt Ms

Yg

Yg Yg

Yac Yg Yg Yac Yac

Yac Yac

Yac

Tc

Qls

Qa

Qg Qg

1,400

1,600

1,800

2,000

2,200

2,400

2,600

2,800

3,000

NO VERTICAL EXAGERATION

NO VERTICAL EXAGERATION NO VERTICAL EXAGERATION

NO VERTICAL EXAGERATION

A

WEST

FEET

5,000

4,000

6,000

7,000

8,000

9,000

10,000

A'

EAST

METERS

IDAHO

MONTANA

IDAHO

MONTANA

MONTANA

IDAHO

COW CREEK THRUST FAULT

DAN PATCH FAULT

BULL MOOSE FAULT

LEMHI PASS FAULT

SECTION

C-C'

Right Fork Peterson Creek

Left Fork Peterson Creek

North Frying Pan Creek

South Frying Pan Creek

BEND IN SECTION

?

Yac Xg

Pp

Ms

Ys

Pp

Ys

PMs

Tg Yg

PMs

Ys

Ms

Ms

Tsu

Mr

Zc

Qt

Yg Ms

Mr

Xg

Mm

Tm

Yg

Ys

PMs Qls Qa

Qt

Qa

Mr

Yg

Mr

Xg Dj

Mb

Tsu

f

f

Ms

Dj

Tsu

f

PMs

Qls

PMs

Pp

Tc

Ms

Qt Qt

Qt

JAKES CANYON

THRUST FAULT

RAILROAD CANYON FAULT

 MAIDEN PEAK FAULT

CABIN THRUST FAULT

Little Eightmile Creek

Irish Boy Springs

Canyon Creek

BEND IN SECTION

B'

EAST

METERS

5,000

4,000

3,000

2,000

6,000

7,000

8,000

9,000

10,000

B

WEST

FEET

JAKES CANYON

MOLLIE GULCH

DEADHORSE

CANYON

SECTION

C-C'

SECTION

D-D'

Tm

Tsu

Ys

Yg

Yac

Zc

PMs

PMs

Pp

Ms

Mr

Mm

Mm

Ms

Mr Ms Ms

Ms

Ms

PMs

PMs

PMs

Mr

Ms Og Qa Qt

Ok

SOs

Ms

Ok

Yg

SOs

Yg

Qa

Mr

South Fork Divide CreekNorth Fork Divide Creek

4,000

3,000

5,000

6,000

7,000

8,000

9,000

C

WEST

FEET

C'

EAST

METERS

IDAHO

MONTANA

SECTION

B–B'

SECTION

D–D'

THRUST DUPLEX

BABY JOE GULCH

THRUST FAULT SYSTEM

JAKES CANYON

THRUST FAULT

THOMPSON GULCH

THRUST FAULT

1,400

1,200

1,000

800

600

1,600

1,800

2,000

2,200

2,400

2,600

2,800

3,000

1,400

1,200

1,000

1,600

1,800

2,000

2,200

2,400

2,600

2,800

1,400

1,200

1,000

1,600

1,800

2,000

2,200

2,400

2,600

2,800

3,000

WAUGH GULCH

34

28

16

18

54

33

7

7

17

26

27

21

18

10

26

7

48

52

19

81

62

80

56

80

75

78

85 77

61

50

33

24 35

36

11

18

43

42 64

18

25 35

38

25

29 36

30

26

54

53 41

53

38

32

22 24

10

47

22

44

76

47

40 62

32

37

31

33

26 30

20

42 33

24

22

39 55 84

23

20 45

23

13

20

39 26

40 40

18

60

38

53

65

62

20

47 61

28

58

33

75

25

25

15

20

63

34

40

55

54

35

53

56

29

25

44

46

32

25

44

42

38

41

32

35

33 23

8

25

28

23

44

24

50

10

50

26

40

33

38

20

32

27

59

58

80

60

71

18

42

36

43

12

18

34

27

72

60

37 47 75

21

67

45

24

66

32

52

20

6

22

65

45

32

20

15

28 35

22

20

45

25

14

43

10

17

3

26

49

52 26

34

36 30 28

22

28

30

26

28

30

29

39

47

20 25

38

20

24

8

10

22

24

54

58

16

25

22

10

25

35

36

20

37

18

32 25 34

40

35

35

30

11

26

35 37

45

34

15

47

40

25

65 32

36

15

17

24

33

46

14

25

22

38

31

27

24

21

23 24

14

40

16

26

21

28

22

30

20

34

19 32

14

7

25 34

14

37

14

28

21

51

20

57

22 20

32

23

10

20

24 24 15

22

16

46

42 16

52

47

48

32

15

14 27

18

27

32

37 46

19

27

43 27

23

28 15

4

30

16

14

55

58

20

22

24

14

22

45 51

25

26

20

18

20 52

46

46

52

7

51

34

48

43 32

50 26 24 10

46

28

18

36

26

35

40

39

22

49

26

6

16

35

16

27

48

34

26

42

42

52

44

18 17

15

30

38

64 20

18

19

30 27

33

44

25

22

28

40

47

28

51

52

75

75

80

50

57

45

23

59

38

88

2

14

60

30

8

6

15

22

12

17

4

19 9

9

12

27

13

12

62 18

34

8

34

18

15

13

16

12

10

14

19 28

13

44

11

23

24

16 22

30

18

27

15

17

15

50

25

35 18

26

18

30

40

15

15

20

28 28

41

20

50

35 25

30 35

55

24

15

5

17

25 40

10 30

30

33

14

35 10

24 50

45

19

26

20

14

25

35

9

15 10

15

25

30

25

22

69

14

26

36

65

16

36 46

30

30 32

35

28 15

44

45

20

15

25

35 55

55 30

20

30

13

60 56 25

33

20

50 15

80 22

30

15

25

52

60

36

34

29

43 27

27 32

29

38

30

17

55

66

57

26

43

34

17

8

18 16

71

15

40

30 25

14

52 17

30

7

64

30 26

45

60 70

70

20

11

40 20 71

15 28

20 28

20

59

14 8

27

10 10 55

20

20

35

5

50

20

35

30

29

17

65

15 37

26

18 10

25

60

28

15

44

15

35 20 20

20

25

10

46

65

30

20

31

30 37

84

26

49

55 23

28

52

19

63

85

39

13

15

5

32

45

17

83

16

30 35

31

69 12

10

24

40

40

75

50 84

40

10

26

15

15

39 30

40

5

20

20 35

10

16 15

15

20

22

22

20

45

40

25

25

30

70

25

15

29

49

55

12

5

11

15

16

20

7

9 17

23

46

33

42

50

36

78

55 66

80

88

59

32 79

13

36

34

20

22

45

74

75

40 75

40

57 77

60

62

67

48

4

33

42

51

39

34

37

42

38

53

37

33

14

46 31

19

24

32

22

32

27

25

33

25

20

47

58

78

18

21

25

21

50

22

29

35 30

16

30 39

47

52

20

77 60

58

80

20

20

37

60

42

44

32

34

52

10

30

45

36

69

32 31

20

12

18

24

8

36

25

35

20

14

54

34

33

64 35

22

28

21

10

32

35

65

31

80

41

67

43

45

55 61

37

36

41

33

51

26

28

75 34

10

76

26

62

34

26 80

20

16 83

77

30

10

25

10

20

25

25

25

29

40

28

39

36

42

55

40

60

50

31

20

25

30

52 40

49

50

35

44

44

42

23

44

46

40

54

50

27

30

30

40

58

35

60 35

38

65

55

40

46

54

40

52

42

45

44

43

45

43

24

50

55

10

40

50

29

2

Figure 4. Stratigraphic correlation chart for units in individual structural domains and subdomains. Location of 

domains, subdomains, and thrust plates are shown in figure 3. Column labeled “Thrust plates north of Goat Mountain 

domain” includes Cow Creek, Lemhi Pass, and Pattee Creek domains plus Shenon Creek thrust plate. Wavy red lines 

indicate angular unconformities.

Xg

Og

f

Pp

Xg

Yac

Yg

Ys

Yac

Yg

Ys

Ok

SOs

Dj Dj

Mm Mm

Ms

Mr

Mm

Ms

Mr

Ms

Mr

d

Yac

Yg

Ys

Yac

Yg

Ys

Yg

Ys Ys

PMs

PMs

Pp

PMs

Pp

PMs

d

Pp

PMs

Ms

Mr

Ms

Mb

?

?

Od

?

?

?

Zc

?

?

Zc

Goat

Mountain

domain

Thrust

plates

north of

Goat

Mountain

domain

Stroud

subdomain

Thrust

duplex

subdomain

Thompson

Gulch

domain

Grizzly Hill domain

Baby Joe

Gulch

domain Rocky

Canyon

subdomain

Cabin

thrust

plate

Maiden

Peak

domain Northwest

Grizzly Hill

subdomain

Salmon basin

Horse

Prairie

basin

Lower Cow Creek–

Agency Creek segment

K e n n e y C r e e k — L e m h i P a s s

b a s i n

COW CREEK THRUST FAULT

RAILROAD

CANYON

FAULT

DEADHORSE

THRUST FAULT

Tend

oy

b

asin

segment

Yearian—

Cow

—Ag

e

n

cy

basin

C O W C R E E K THRUST F A U L T

L e m h i b a s i n

Leadore basin segment

JAKES CANYON

THRUST FAULT

CEDAR

CANYON

FAULT

BABY JOE

GULCH THRUST

FAULT

ROCKY CANYON FAULT CABIN

THRUST

FAULT

GOAT MOUNTAIN—BLACK CANYON FAULT SYSTEM

COW CREE

TH

K

RUST FAU LT

L E M H I PA S S N O R M A L F A U L T

BULL MOOSE FAULT

DAN PATCH FAULT

LITTLE EIGHTMILE FAULT SYSTEM

HORSE PRAIRIE BASIN FAULT

MAIDEN PEAK FAULT

BIG HOLLOW

THRUST FAULT

SHENON CREEK

THRUST

FAULT

Little

Eightmile

basin

THOMPSON

GULCH

THRUST

FAULT 

THOMPSON GULCH

THRUST FAULT 

BABY JOE GULCH

THRUST FAULT

45°

44°50'

44°40'

113°40' 113°30' 113°20' 113°10'

Base from U.S. Geological Survey digital data,

The National Map, 2017

Universal Transverse Mercator projection, zone 12N

North American Datum of 1983

0 2 4 6 8 KILOMETERS

0 2 4 6 8 MILES

Basin boundary

Grizzly Hill

domain

Transcurrent fault

Normal fault

Thrust fault

Map boundary

EXPLANATION

Goat Mountain domain

Northwest Grizzly Hill subdomain

Stroud subdomain

Thrust duplex subdomain

Rocky Canyon subdomain

Lemhi Pass domain

Shenon Creek thrust plate

Cow Creek thrust plate

Pattee Creek domain

Basins

Cabin thrust plate

Baby Joe Gulch domain

Thompson Gulch domain

Maiden Peak domain

Figure 3. Index map showing locations of named structures, structural domains, and topographic features.

MONTANA

IDAHO

Map area

Figure 2. Index map showing areas of previous mapping in the study area. 1, Blankenau (1999); 

2, Lucchitta (1966); 3, Lund and others (2003b); 4, M’Gonigle (1994); 5, M’Gonigle and Hait (1997); 6, 

Ruppel (1968); 7, Staatz (1972); 8, Staatz (1973); 9, Staatz (1979); 10, VanDenburg (1997); 11, Hansen 

(1983).

Extent of geologic

mapping, this

publication

IDAHO

MONTANA

CUSTER

COUNTY

6

8

2

4

10

11

BEAVERHEAD CO

LEMHI CO

5

1

3

7

9

113°40' 113°30' 113°20' 113°10'

45°

44°50'

44°40'

IDAHO

MONTANA

Study area

SALMON

NATIONAL

FOREST

SALMON

NATIONAL

FOREST

BEAVERHEAD

NATIONAL

FOREST

BEAVERHEAD

 NATIONAL

FOREST

SALMON

 NATIONAL

FOREST

CHALLIS

 NATIONAL

 FOREST

BEAVERHEAD NATIONAL

FOREST

Lemhi

Salmon

Leadore Lemhi Range

Central Beaverhead Mountains

Maiden Peak spur

Tendoy Mountains

River

Lemhi

SALMON

NATIONAL

FOREST

BEAVERHEAD

NATIONAL

FOREST

CHALLIS

NATIONAL

FOREST

15

93

93

278

28

Base from U.S. Geological Survey digital data,

The National Map, 2017

Universal Transverse Mercator projection, zone 12N

North American Datum of 1983

LEMHI COUNTY

CUSTER COUNTY

0 4 8 12 16 20 KILOMETERS

0 4 8 12 16 20 MILES

114° 113°30' 113°

45°

44°30'

Lemhi

Pass

Bannock

Pass

BEAVERHEAD

COUNTY

LEMHI

COUNTY

IDAHO

MONTANA

Map area

Figure 1. Index map showing the study area and nearby geographic features. 

Og

Qt

Qa

Og

Ms

Yg

Yac

Ys

Ys

N

B

J

G T F S

B

J

G

T F S

Jakes Canyon

T GT

F

Og Mm

Mm

Mm

Yg

THOMPSON GULCH

THRUST FAULT

BABY JOE GULCH

THRUST FAULT SYSTEM

Mm

Yg

Ms

Three-dimensional image showing Thompson 

Gulch thrust fault (TGTF) carrying Mississippian 

Middle Canyon Formation and the overlapping Baby 

Joe Gulch thrust fault system (BJGTFS) carrying 

Early Ordovician-Late Cambrian Beaverhead 

Mountains syenogranite. View is to the north 

across mouth of Jakes Canyon. Qa, alluvium; Qt, 

terrace deposits; Mm, Middle Canyon Formation; 

Ms, Scott Peak Formation; Og, syenogranite; Ys, 

Swauger Formation; Yg, Gunsight Formation; Yac, 

coarse siltite unit of Apple Creek Formation.

Image by Stuart A. Giles. 

Photograph showing field view 

of part of the area shown in the 

draped image. View is to the 

north across Jakes Canyon.

Photograph by K. Lund, 2014.

Contact—Dashed where approximately located

Angular unconformity—Dashed where approximately located 

Normal fault—Ball and bar on downthrown block

Thrust fault—Sawteeth on downthrown block

EXPLANATION

Photograph of angular unconformity (red line) between Mesoproterozoic Gunsight 

Formation (Yg) and overlying Mississippian Middle Canyon and Scott Peak Formations 

(Mm and Ms, respectively). View looks southwest from Goat Mountain toward lower 

Little Eightmile Creek. Mountain goats along ridgeline, stratigraphically above the 

unconformity. White line indicates unit contact. Photograph by K. Lund, 1996.

Ms

Ms

Ms

Mm

Ms Ms

Ms

Ms

Ms

Pp

Ms

Ms

Ms

Ms

Ms

Ms

Mr

Ms

Qls

d

d

Qls

Qls

Qt

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Qls

Xg

Xg

Xg

Qls

Qls

Qls

Qls

Qls

Ys

Ys

Ys Qg

Ys

Ys

Ys

Ys

Yg

Ys

Ys

Ys

Ys

Mb

Od

Od

Tc

Yac

Yac

Yac

Yac

Yac

Yac

Yac

Yac

Yac

Yac

Yac

Yac

Yac

Yac

Tc

Tc

Tc

Tc

Tc

Tr

Tc

Tc

Tc

Tc

Qt

Qt

Qt

Qls

Qls

Qls

Qls Qls

Qa

Tc

Tc

Tc

Tc

Tc

Tc

Tc

Tc

Tc

Tc

Tc

Tsl

Tc

Tc

Tc

Tc

Tc

Tc

Tc

Tc

Tc

Tc

Yg

Yg

Yg

Yg

Yg

Yg

Yg

Yg

Yg

Yg

Yg

Yg

Tsu

Yg

Yg

Yg

Yg

Yg

Yg

Yg

Yg

Yg

Yg

Mr

Mr

Mr

Mr

Mr

Zc

Zc

Zc

Zc

Zc

Pp

Pp

Tg

Pp

Pp

Pp

Pp

Ok

Ok

Dj Dj

Ok

Ok Ok

SOs

SOs

Dj

Dj

Dj

Og

Dj

Dj

SOs

SOs

SOs

PMs

PMs

PMs

PMs

PMs

PMs

PMs

PMs

PMs

PMs

PMs

Tsu

Tsu

Tsu

Tsl

Tm

Tsl

Td

Tsu

Tsu

Tsl

Tsu

Tsu

Tsu

Tsu

Tsu

Tsu

Tsl

Tsl

Tsl

Tsl

Tr

Tsl

Tsl

Tsl

Tsl

Tsl

Tsl

Tsl

Tsl

Tsl Tsl

Tsl

Tr

Tr

Tr

Qg

Qg

Qg

Qg

Qt

Qt

Qt

Qt

Qt

Qt

Qt

Qt

Qt

Qa

Qt

Qt

Qt

Qt

Qt

Qt

Qt

Qt

Qt

Qt

Tm

Tm

Tm

Tm

Tm

Tm

Td

Td

Td

Td

Xg

Mm

Mm

Mm

Mm

Og

Og

Og

Tr

Og

Xg

Qa

Qa

Qa

Qa

Qa

Qa

Qa

Qa

Qa

Qa

Qa

Qa

Qa

Qa

Qa

Tg

f

Qa

Dj

f

Tr

Tr

Tr

Tr

Tr

Tr

Ms

Yac

Ms Yg

EXPLANATION

Contact—Long dashed where approximately located, dotted where concealed 

Bedding (on cross section only)

Cleavage (on cross section only)

Angular unconformity—Long dashed where approximately located, dotted 

where concealed. Major unconformities above Paleoproterozoic and 

Mesoproterozoic units. Lesser unconformities within Mesoproterozoic 

and Paleozoic sections. Mesoproterozoic-Paleozoic unconformity locally 

tectonized

Fault—Complex movement, generally oblique reverse motion or oblique 

thrust-ramp geometry. Arrows show relative motion where strike-slip 

component is mapable. Long dashed where approximately located, 

dotted where concealed

Normal fault—Ball and bar on downthrown block. Long dashed where 

approximately located, dotted where concealed

Low-angle normal fault—Half-circles on downthrown block. Long dashed 

where approximately located, dotted where concealed

Reactivated fault—Ball and bar and sawteeth on downthrown block. Dotted 

where concealed

Thrust fault—Sawteeth on downthrown block. Long dashes where approximately located, dotted where concealed. Fault attitude tick shows dip

Strike-slip fault (on cross section only)—minus, away from observer; plus, 

toward observer

Anticline

Overturned anticline—Beds on one limb are overturned; arrows show dip 

direction of limbs. Dotted where concealed

Syncline—Dotted where concealed

Overturned syncline—Beds on one limb are overturned; arrows show dip 

direction of limbs

PLANAR POINT FEATURES

Inclined bedding—Showing strike and dip

Inclined bedding, upright—Where top direction of beds is known from 

primary sedimentary features. Showing strike and dip

Overturned bedding—Where top direction of beds is known from primary 

sedimentary features. Showing strike and dip

Inclined metamorphic foliation—Showing strike and dip

Inclined axial planar foliation—Showing strike and dip

Inclined cleavage—Showing strike and dip

Vertical cleavage—Showing strike

Inclined flow layering in volcanic rock—Showing strike and dip

Inclined lineation at intersection of bedding and cleavage—Showing 

bearing and plunge

Inclined aligned-mineral lineation—Showing bearing and plunge

Inclined slickenside on fault surface—Showing bearing and plunge

Inclined fold hinge of small, minor fold—Showing bearing and plunge

Horizontal fold hinge of small, minor fold—Showing bearing and plunge

Inclined asymmetric (S-shaped, counterclockwise sense of shear) minor 

fold hinge—Showing bearing and plunge

Inclined asymmetric (Z-shaped, clockwise sense of shear) minor fold 

hinge—Showing bearing and plunge

Horizontal asymmetric (Z-shaped, clockwise sense of shear) minor fold 

hinge—Showing bearing and plunge

AREAL FEATURES

Breccia—Associated with landslide blocks and major low-angle normal fault 

zone

18

38

81

30

20

10

35

36

55

26

54

2

16

Xg

Yac

Yg

Ys

Og

Zc

f

Od

Ok

SOs

Dj

Mm

Ms

Mr

Mb

PMs

Pp

d

Tg

Td

Tc

Tsl

Tsu

Tm

Qt

Qg

Qls

Qa

Tr

LIST OF MAP UNITS

[See Description of Map Units (in pamphlet) for complete unit descriptions. Due to the 

addition of a shaded relief base, colors in the List of Map Units may not exactly match 

unit colors on the map] 

SURFICIAL DEPOSITS

Alluvium (Holocene)

Landslide deposits (Holocene and Pleistocene)

Glacial deposits (Holocene and Pleistocene)

Terrace deposits (Holocene and Pleistocene)

CENOZOIC SEDIMENTARY ROCKS

Mudstone deposits (middle Miocene)

Basin-fill deposits, upper (lower Miocene to Oligocene)

Basin-fill deposits, lower (Oligocene to upper Eocene)

EOCENE CHALLIS VOLCANIC-PLUTONIC COMPLEX

CHALLIS VOLCANIC GROUP

Challis Volcanic Group, undivided

INTRUSIVE ROCKS

Rhyolite dike

Granite

Mafic dike

MESOZOIC TO NEOPROTEROZOIC? SEDIMENTARY 

AND METASEDIMENTARY ROCKS

Dinwoody Formation (Lower Triassic)

Phosphoria Formation (Permian)

Snaky Canyon Formation, undivided (Lower Permian to Upper 

Mississippian)

Bluebird Mountain Formation (Upper Mississippian)

Railroad Canyon Formation (Upper Mississippian)

Scott Peak Formation (Middle Mississippian)

Middle Canyon Formation (Middle and Lower Mississippian)

Jefferson Formation (Upper Devonian)

Saturday Mountain Formation (Lower Silurian to Middle

Ordovician)

Kinnikinic Quartzite (Middle Ordovician)

Dolostone (Middle Ordovician? to Upper Cambrian?)

Flathead Quartzite (Middle Cambrian)

Conglomerate (Lower Cambrian? to Neoproterozoic?)

PALEOZOIC INTRUSIVE ROCKS

Syenogranite (Early Ordovician to Late Cambrian)

MESOPROTEROZOIC METASEDIMENTARY ROCKS

Swauger Formation (Mesoproterozoic)

LEMHI GROUP

Gunsight Formation (Mesoproterozoic)

Coarse siltite unit of Apple Creek Formation (Mesoproterozoic)

PALEOPROTEROZOIC INTRUSIVE ROCKS

Orthogneiss (Paleoproterozoic)

SURFICIAL DEPOSITS

Holocene

Pleistocene

CENOZOIC

SEDIMENTARY

UNITS

INTRUSIVE ROCKS

CHALLIS

VOLCANIC

GROUP

EOCENE CHALLIS 

VOLCANIC-PLUTONIC COMPLEX

QUATERNARY

TERTIARY

Lower

PERMIAN

TRIASSIC

MISSISSIPPIAN

PENNSYLVANIAN

Upper

Upper

DEVONIAN

PALEOZOIC

INTRUSIVE

ROCKS

Lower SILURIAN

Middle ORDOVICIAN

Upper

CAMBRIAN

Lower

Lower

Neoproterozoic MESOPROTEROZOIC

METASEDIMENTARY ROCKS

PROTEROZOIC

Paleoproterozoic

Miocene

Oligocene

Eocene

Lower

Middle

Upper

MESOZOIC TO NEOPROTEROZOIC?

SEDIMENTARY AND

METASEDIMENTARY ROCKS

PALEOPROTEROZOIC

INTRUSIVE ROCKS

Middle

Mesoproterozoic

CORRELATION OF MAP UNITS

[See Description of Map Units (in pamphlet) for precise unit ages]

?

?

?

?

d

Pp

PMs

Mb

Mr

Ms

Mm

Dj

SOs

Ok

Og Od

f

Zc

Ys

Yg

Yac

Xg

Qa Qls

Qg Qt

Tm

Tsu

Tsl

Tc Tr Tg Td

LEMHI

GROUP

BACHELOR

MOUNTAIN

GOLDSTONE KITTY CREEK COYOTE CREEK

MOUNTAIN

BAKER

TENDOY

HAYDEN

CREEK

LEMHI GOAT

MOUNTAIN

BANNOCK

PASS

MOGG STROUD CREEK LEADORE

MOUNTAIN

AGENCY CREEK LEMHI PASS EVERSON

CREEK

JEFF DAVIS

PEAK

113°45' 113°37'30" 113°30' 113°22'30" 113°15' 113°07'30"

45°07'30"

45°00'

44°52'30"

44°37'30"

44°45'

Map area

Index map showing map area in yellow with 7.5' U.S. 

Geological Survey quadrangles.

WEST OF

LEADORE

RESERVOIR

CREEK

DEADMAN

PASS

Base modified from U.S. Geological Survey, Baker, Idaho, 2017; Goldstone Mountain, 

Idaho-Mont., 2017; Kitty Creek, Mont.-Idaho, 2017; Coyote Creek, Mont., 2017; Bachelor 

Mountain, Mont., 2017; Tendoy, Idaho, 2017; Agency Creek, Idaho, 2017; Lemhi Pass, 

Mont.-Idaho, 2017; Everson Creek, Mont., 2017; Jeff Davis Peak, Mont., 2017; Hayden Creek, 

Idaho, 2017; Lemhi, Idaho, 2017; Goat Mountain, Idaho-Mont., 2017; Bannock Pass, 

Mont.-Idaho, 2017; Deadman Pass, Mont.-Idaho, 2017; Mogg Mountain, Idaho, 2017; Stroud 

Creek, Idaho, 2017; West of Leadore, Idaho, 2017; Leadore, Idaho, 2017; Reservoir Creek, 

Idaho-Mont., 2017

North American Datum of 1983 (NAD83)

Shaded relief base from The National Map, accessed 2017, at

https://www.usgs.gov/core-science-systems/ngp/tnm-delivery

World Geodetic System of 1984 (WGS84). Projection and 1,000-meter grid: Universal 

Transverse Mercator, Zone 12T

Geologic mapping by K. Lund 1996−2002, 2014−2017. Bedrock geology along eastern margin of map is a combination of new 

geologic mapping and compilation from Lucchitta (1966), M'Gonigle (1994), and M'Gonigle and Hait (1997). Basin geology 

generalized from VanDenburg (1999) and Blankenau (1997)

GIS database and digital cartography by 

Stuart A. Giles and K. Lund

Publishing support provided by Denver Publishing Service Center

Edit and cartographic layout by Anya V. Hess and L.J. Binder

Manuscript approved for publication August 21, 2018

APPROXIMATE MEAN

DECLINATION IN 

CENTER OF SHEET, 

2018 TRUE NORTH

MAGNETIC NORTH

12.7°

Geologic Map of the Central Beaverhead Mountains, Lemhi County, Idaho, and Beaverhead County, Montana

By

Karen Lund 

2018

ISSN 2329-132X (online)

https://doi.org//10.3133/sim3413

This map or plate is offered as an online-only, digital publication. Users should be aware 

that, because of differences in rendering processes and pixel resolution, some slight 

distortion of scale may occur when viewing it on a computer screen or when printing it on 

an electronic plotter, even when it is viewed or printed at its intended publication scale.

Any use of trade, firm, or product names is for descriptive purposes only and does not imply

endorsement by the U.S. Government.

Although this information product, for the most part, is in the public domain, it also may 

contain copyrighted materials as noted in the text. Permission to reproduce copyrighted 

items must be secured from the copyright owner.

SCALE 1: 50 000

1 1/ 2 0 1 2 3 4 MILES

3000 0 3000 6000 9000 12000 15000 18000 21000 FEET

1 .5 0 1 2 3 4 5 KILOMETERS

Map location

MONTANA

IDAHO

CONTOUR INTERVAL 40 FEET

NORTH AMERICAN VERTICAL DATUM OF 1988

LEMHI

PASS

FAULT

NORMAL

DAN

PATCH

FAULT

BULL

MOOSE

FAULT

FAULT

MOOSE

BULL

HORSE

GOAT

MOUNTAIN–

BLACK

CANYON

FAULT

SYSTEM

LITTLE

EIGHTMILE

FAULT

SYSTEM

THRUST

THOMPSON

BABY

JOE GULCH THRUST

FAULT SYSTEM

MAIDEN PEAK

FAULT

MAIDEN PEAK FAULT

COW

CREEK

THRUST

FAULT

PRAIRIE

BASIN

FAULT

MOUNTAIN –

BLACK

CANYON FAULT

SYSTEM

DEADHORSE 

THRUST 

FAULT

CABIN 

THRUST 

FAULT

DEADHORSE 

THRUST 

FAULT

THOMPSON 

GULCH 

THRUST 

FAULT

BABY JOE 

GULCH 

THRUST 

FAULT 

SYSTEM

THOMPSON GULCH

THRUST

FAULT

RAILROAD 

CANYON 

FAULT

JAKES

CANYON

FAULT

GULCH

THRUST FAULT

ROCKY

CANYON

FAULT

THOMPSON

GULCH

THRUST

FAULT

COW CREEK

THRUST

FAULT

GOAT

COW

CREEK

THRUST FAULT

A'

A

D

D'

B

B'

C

C'

SHENON

THRUST

FAULT

For more information concerning the research in this report, contact the

Center Director, USGS Geology, Geophysics, and Geochemistry Science Center

Box 25046, Mail Stop 973

Denver, CO 80225

(303) 236-1800

Or visit Geology, Geophysics, and Geochemistry Science Center website at

https://www.usgs.gov/centers/gggsc

ScienceBase GIS files and other files that support this report are available at 

https://doi.org/10.5066/P905PTI4

Report digital files available at https://doi.org/10.3133/sim3413

Suggested citation: Lund, K., 2018, Geologic map of the central Beaverhead Mountains, Lemhi County, 

Idaho, and Beaverhead County, Montana: U.S. Geological Survey Scientific Investigations Map 3413, 

pamphlet 27 p., scale 1:50,000, https://doi.org/10.3133/sim3413.

THOMPSON GULCH

THRUST FAULT THOMPSON

GULCH

THRUST

FAULT

13° 22 '30 "

113°30'

44°45'

113°37'30"

44°52'30"

45°

113°37'30"

113°30'

113°15’

113°22'30" 113°15'

45°

44°52'30"

44°45'

1

U.S. Department of the Interior

U.S. Geological Survey

Scientific Investigations Map 3413

Pamphlet accompanies map