LIST OF MAP UNITS

Alluvium (Holocene)

Alluvium and colluvium, undivided (Holocene)

Colluvium (Holocene)

Landslide deposits (Holocene and Pleistocene)

Terrace gravel (Holocene? and Pleistocene)

Old alluvium (Holocene? or Pleistocene)

Older gravel (Pleistocene? and Neogene?)

Sedimentary rocks (Miocene and Oligocene)—Shown as MIOGS in Reynolds and Brandt, 2005, 2007

Basalt (Oligocene)—Shown as OGb in Reynolds and Brandt, 2005, 2007

Biotite hornblende dacite (Eocene)—Shown as EObhd in Reynolds and Brandt, 2005, 2007

Biotite hornblende monzonite (Eocene)—Shown as EObhm in Reynolds and Brandt, 2005, 2007

Park Shale (Upper and Middle Cambrian)

Meagher Limestone (Middle Cambrian)

Wolsey Shale (Middle Cambrian)

Flathead Sandstone (Middle Cambrian)

Belt Supergroup, part (Mesoproterozoic)

Newland Formation (Mesoproterozoic)

Newland Formation, upper part (Mesoproterozoic)

Newland Formation, lower part (Mesoproterozoic)

Granite gneiss (Paleoproterozoic)

Granite gneiss and biotite gneiss undivided (Paleoproterozoic)

Biotite hornblende diorite (Paleoproterozoic)

EXPLANATION

Contact—Dashed where approximately located, short dashed, where inferred, dotted where concealed

Boundary of mapped surficial material or feature—Approximately located

Fault—Dashed where approximately located, short dashed, where inferred, dotted where concealed

Normal Fault—Ball and bar on downthrown block; dashed where approximately located, short dashed 

where inferred, dotted where concealed; red arrow indicates fault attitude showing dip 

Anticline—Dashed where approximately located, short dashed where inferred, dotted where concealed; 

arrow shows direction of plunge

Syncline—Dashed where approximately located, short dashed where inferred, dotted where concealed

Bed or vein of iron-silicate gossan

Outcrop of iron oxide gossan zones—In bedrock of the Newland Formation

Area of iron-oxide-stained bedrock, bedrock fragments and soil—Near zones of sulfide mineralization

Area of colluvial boulders, blocks and cobbles of iron-silicate gossan—Derived from nearby zones of 

sulfide mineralization

Area of alluvial and colluvial boulders, cobbles, and blocks—Derived from Paleozoic strata east of the 

quadrangle or from Flathead Sandstone on Black Butte

Zone of brecciated and sheared rock adjacent to fault

Horizontal bedding

Inclined bedding—Showing strike and dip

Vertical bedding—Showing strike

Overturned bedding—Showing strike and dip

Inclined shear fracture—Showing strike and dip

Inclined layering in layered gneiss or schist—Showing strike and dip

Inclined slickensides—Showing bearing and plunge

Location and age of dated rocks—Showing sample number and radiometric age

Selected locality of trace fossils in Flathead Sandstone

Prospect pit in iron oxide gossan zone

Exploration trench in iron oxide gossan zone

Qt

Ql

Qc

Qa

p

b

f

w

m

bhd

Ynu

Ynl

Xgg

Xgbg

Xbd

QNg

bhm

85

27

Ns

Qac

Qoa

Figure 3. Tectonic map of west-central Montana showing principal faults, major tectonic elements, intrusive and extrusive igneous rock bodies, Tertiary strata and major areas of Quaternary sediments. Thrust sheets and igneous units listed in descending succession 

of inferred increasing age within tectonic elements (for example, autochthons and parautochthons). Red rectangular outline shows the location of the Strawberry Butte 7.5 ́ quadrangle (modified from Reynolds and Brandt, 2005, figure 2, sheet 1).

C

C C

C

C

C

0 2 4 6 8 10 KILOMETERS

0 2 4 6 8 10 MILES

Area of

Figure 3

MONTANA

FAULT

CARR

WOODS

CREEK

RIDGE

SMITH VALLEY

EAST SIDE FAULT

LOST FORK 

PLUTON

CREEK

FAULT

NORTH

FAULT

LACCOLITH

ZONE

ZONE

MOUNTAIN

SHEEP

MOUTAIN

FLANK

VALLEY

LOGAN

FAULT

CAMUS CREEK FAULT

BIG BALD

MOUNTAIN

LACCOLITH

BOULDER

BALDY

PLUTON

FORT

PLUTON

BASIN

THRUST

FAULT

FAULT

CREEK

TENDERFOOT

NEVADA CREEK

FAULT

DECOLLEMENT 

FAULT

FAULT

ZONE

RANGE

FAULT

DRYWOLF

LACCOLITH

WAITE

ZONE

MOOSE

ZONE

CREEK

FAULT

CASTLE

MOUNTAINS

PLUTON

ZONE

CREEK

FAULT

PARK

QUARTZITE

WESTERN END

ANCESTRAL CENTRAL MONTANA

UPLIFT

DRY

FAULT

HOOVER

White

Sulphur

Springs

Utica

Neihart

111°22' 111°00' 110°30' 110°00'

47°00'

46°30'

46°45'

R

C

Quaternary and Pliocene(?) sediment in veneers on older

 rocks—Locally includes Miocene and Oligocene

 sedimentary rocks in valley of Smith River

Miocene and Oligocene sedimentary rocks—Locally includes

 Eocene(?) sedimentary rocks at base

Oligocene basalt

Oligocene(?) and Eocene rhyolite with breccia blocks of

 Paleozoic sedimentary rocks

Eocene intrusive rocks—In plutons, laccoliths, and large sills of

 the autochthon and parautochthon

Eocene and Cretaceous intrusive rocks penetrating the Moors

 Mountain thrust sheet

Paleozoic sedimentary rocks of the frontal fold-and-fault belt

Neoproterozoic diorite sill in Moors Mountain thrust sheet

Mesoproterozoic metasedimentary rocks of the Moors

 Mountain thrust sheet

Mesozoic sedimentary rocks of the paratochthon—Become

 contiguous with the autochthon in T8N, R19E

Paleozoic sedimentary rocks of the paratochthon—Become

 contiguous with the autochthon in T8N, R19E

EXPLANATION

 [Thrust sheets and igneous units listed in descending succession of

inferred increasing age; some Quaternary and Tertiary deposits are not shown]

R

R

R

Mesozoic sedimentary rocks of the autochthon

Paleozoic sedimentary rocks of the autochthon; locally includes

 Eocene sills and dikes

Mesoproterozoic metasedimentary rocks of the paratochthon

Lewis and Clark tectonic zone—Boundaries inferred

Stratigraphic boundary

Major high-angle normal fault—Bar and ball on downthrown block

Major fault with complex displacement—Including normal,

 strike-slip and reverse movement through geologic time

Major high-angle reverse fault—R on upthrown block

Edge of major thrust sheet—Sawteeth on upper plate

Edge of decollement surface at base of frontal fault and fold belt

Fault—Dotted where concealed by Cenozoic units or water

Neoarchean metamorphic rocks of the autochthon

Paleoproterozoic metamorphic rocks of the autochthon

Mesoproterozoic metasedimentary rocks of the autochthon

MOORS

BLACK CANYON

LEWIS AND CLARK TECTONIC ZONE

THRUST

VOLCANO

VOLCANO

VALLEY

FAULT

MOUNTAIN

Figure 2. Shaded relief map of the Strawberry Butte 7.5 ́ quadrangle (red rectangle) and adjacent areas showing features referred to in the 

accompanying pamphlet. Selected streams, blue; roads and vehicle trails, black and gray lines respectively; quadrangle names, green; Lewis 

and Clark National Forest exterior boundary, dashed and orange lines. There are private inholdings within the boundaries of the National 

Forest shown on this map.

0 1 2 3 4

0 1 2 3 4

5 MILES

5 KILOMETERS

1:200,000

Creek

Black

Butte Creek Black

Butte

Strawberry

Butte

Coxcombe

Butte

Moose

Mountain

Allan

Park

Sheep

Creek

Bar

Green

Mountain

Williams

Mountain

Monument

Peak

Iron

Mountain

Belt Park

Quartzite Ridge

Buckingham

Reservoir

Newlan Creek

Reservoir

Sheep Creek

Moose Creek

 Creek

Sheep

Newlan 

Creek

Newlan

Creek

Tenderfoot

Eagle

Smith

River

Rabbit

Creek

Adams

Creek

Creek

Pole Creek

CASCADE COUNTY

MEAGHER COUNTY

Rimrock Ridge

89

89

89

360

259

111°7’30”

47°

46°52’30”

46°45’

46°37’30”

111°

NATIONAL FOREST

LEWIS AND CLARK

Creek

U.S. Geological Survey National Elevation Dataset (NED)

10-meter resolution elevation data, accessed on 07-25-2016

Lake

110°52’30” 110°45’

Charcoal Gulch

Sheep

Mountain

MONUMENT

PEAK

BUBBLING

SPRINGS

BELT PARK

BUTTE

SHEEP

MTN

STRAWBERRY

BUTTE

MOOSE

MTN

WHITETAIL

RESERVOIR COXCOMBE

BUTTE

CHARCOAL

GULCH

MONUMENT

PEAK

BUBBLING

SPRINGS

BELT PARK

BUTTE

SHEEP

MTN

STRAWBERRY

BUTTE

MOOSE

MTN

WHITETAIL

RESERVOIR

CHARCOAL

GULCH

BUBBLING

SPRINGS

SHEEP

MTN

STRAWBERRY

BUTTE

MOOSE

MTN

WHITETAIL

RESERVOIR COXCOMBE

BUTTE

CHARCOAL

GULCH

Figure 1. Generalized physiography of west-central Montana, showing location of the Strawberry Butte and adjacent 7.5 ́ quadrangles 

referred to in the text and annotated with names of selected topographic and cultural features; orange shading indicates highlands and green 

indicates lowlands. 

Missouri River

0

0

5

5

10

10

15

15

20 MILES

20 KILOMETERS

Niehart

White Sulphur

Springs

111°30’ 111° 110°30’

47°

46°30’

Adel

Mountains

Castle

Mountains

Elkhorn

Mountains

Spokane Hills

Dry Range

Park

Hills

Little Belt Mountains

Smith River

Valley

Townsend

Valley

Sheep

Mountain

Strawberry

Butte

Moose

Mountain

Judith River

basin

Helena

Valley

Missouri River

Smith River

North Fork Smith River

South Fork Smith River

Musselshell River

B

Judith River

ig

Belt

Mountains

Canyon Ferry

Lake

?

?

?

?

Qa Qc

Ql Qt

b

bhd

Ynu

Ynl

Xgg

Xgbg

Xbd

QUATERNARY

TERTIARY

CAMBRIAN

MESOPROTEROZOIC

PALEOPROTEROZOIC

Holocene

Oligocene

Upper Cambrian

Middle Cambrian

BELT SUPERGROUP

(part)

Pleistocene

Pliocene(?) and Miocene

Fault contacts

Unconformity

Unconformity

Unconformity

Intrusive contacts

CORRELATION OF MAP UNITS

Eocene

p

m

f

w

5

WSP9–99

31.71 Ma

Qoa QNg

Ns

bhm

75

73

80

Qac

52

5

WSP8b–99

31.87 Ma

WSP9–99

31.71 Ma

75

10

10

5

5 68

7

9

10

58

32

3

13

42 85

10

7

10

20

5 4

5

8

88 80

4

37

12

17

18

23

15 20 24 4

32

35 35

80

48

70 45

27

18

40

24

30

55

12 27

35

20

16

27

20

33

80

80

85

67

73

85

WSP8a–99

32.04 Ma

Ynu

Qa

Ql

m

f

Ynu

Ynl

Ynu

Qa

f

m

Qa

m

f

f

f

f

Qt

Qa

Qa

Qa

Xgg

Xgg

Xgg

Xgg

Xgg

Xgg

f

f

f

f

f

Ql

Ql

w

Qa

Xbd

Xbd

m

Qa

Qt

Qa

w

f

f

f

QNg

Ynl

QNg

Ynu

QNg

f

Xgg

Xgbg

Xgbg

FAULT

FAULT

VOLCANO

VALLEY

BLACK BUTTE

CREEK

ZONE

ZONE

Qac

Ns

Ns

Ns

Ns

Qa

b

b

Qa

b

Ns

Ns

Ns

Ns

bhm b

bhd

bhd

bhd

b

Qac

QNg

f

Qa

Qa

Qa

p p

f

Qc

Ql

Qoa

Ns

Ynl

Xgbg

BLACK

BUTTE

CREEK

ZONE

FAULT

Geologic Map of the Strawberry Butte 7.5’ Quadrangle,

Meagher County, Montana

By

Mitchell W. Reynolds and Theodore R. Brandt 

2017

CONVERSION FACTORS

2.54 centimeter (cm)

25.4 millimeter (mm)

0.3048 meter (m)

1.609 kilometer (km)

Multiply

Length

By To obtain

inch (in.)

inch (in.)

foot (ft)

mile (mi)

U.S. Customary Units to International System

U.S. Department of the Interior

U.S. Geological Survey

https://doi.org/10.3133/sim3379

ISSN 2329-132X (online)

For more information concerning this publication, contact

Center Director, USGS Geosciences and Environmental Change Science Center

Box 25046, Mail Stop 980

Denver, CO 80225

(303) 236-5344

Or visit the Geosciences and Environmental Change Science Center Web site at http://gec.cr.usgs.gov/

ScienceBase citation: Reynolds, M.W., and Brandt, T.R., 2017, Data release for the geologic map of the Strawberry Butte 

7.5’ quadrangle, Meagher County, Montana: U.S. Geological Survey data release, https://doi.org/10.5066/F73J3B61. 

Suggested citation: Reynolds, M.W., and Brandt, T.R., 2017, Geologic map of the Strawberry Butte 7.5’ quadrangle, 

Meagher County, Montana: U.S. Geological Survey Scientific Investigations Map 3379, pamphlet 16 p., 2 sheets, scale 

1:24,000, https://doi.org/10.3133/sim3379.

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.

This database, identified as SIM 3379, has been approved for release and 

publication by the U.S. Geological Survey (USGS). Although this database has been 

subjected to rigorous review and is substantially complete, the USGS reserves the 

right to revise the data pursuant to further analysis and review. Furthermore, the 

database is released on condition that neither the USGS nor the U.S. Government 

shall be held liable for any damages resulting from its authorized or unauthorized 

use.

Although these data have been processed successfully on a computer system at the 

U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding 

the display or utility of the data on any other system or for general or scientific 

purposes, nor shall the act of distribution constitute any such warranty. The USGS 

or the U.S. Government shall not be held liable for improper or incorrect use of the 

data described and/or contained herein.

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 or color 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.

Base from U.S. Geological Survey Strawberry Butte 1:24:000-scale, 1967

Revised by U.S. Forest Service Strawberry Butte 1:24,000-scale, 1995

Projection and 1,000-meter grid

Universal Transverse Mercator ticks, zone 12

10,000-foot ticks, Montana coordinate system, central zone

1927 North American Datum

Geology mapped by Mitchell W. Reynolds in July 1998 

and July 1999; assisted by Sandra A. Reynolds

Digital topographic base map, digital compilation, and 

geographic information systems (GIS) database 

prepared by Theodore R. Brandt

Color design of map and figures by Mitchell W. Reynolds

Scientific Investigations Map 3379

Sheet 1 of 2

Pamphlet accompanies map

CONTOUR INTERVAL 40 FEET

NATIONAL GEODETIC VERTICAL DATUM OF 1929

APPROXIMATE MEAN

DECLINATION, 2016

QUADRANGLE LOCATION

SCALE 1: 24 000

1 1/ 2 0 1 MILE

1000 0 1000 2000 3000 4000 5000 6000 7000 FEET

1 .5 0 1 KILOMETER

TRUE NORTH

MAGNETIC NORTH

12°

MONTANA

Publishing support provided by 

Denver Publishing Service Center

Edit and digital layout by J.A. Herrick

Manuscript approved for publication March 15, 2017

To learn about the USGS and its information products visit

http://www.usgs.gov/

1-888-ASK-USGS

A'

B'

A B

C'

C