Tfbu

Kag

Tsi

Tsi

Tsm

Qc

Qc

Qc

Qc

Qlu

Qlu

Qc

Qc

Qlp

Qc

Qc

Qc

Qc

Qc

Qc

Qc

Qc

Tcbr

Qoa

Qoa

Tckss

Qoa

Qoa

Qc

Qc

Qc

Qc

Qc

Qc

Qc

Qc

Qc

Qlu

Qc

Kag

Kag

Kag

Kag

Tcl

Tii

Kag

Tsi

Kag

Tsm

Tsm

Qrf

Qrf

Qrf

Qrf

Qrf

Tcss Tcstr

Tcstr

Tcstr

Tdr

Teeb

Terf

Tir

Tir

Tdr

Tcstr

Tdsm

Tcstr

Tcstr

Tinm

Tinm

Tinm

Tinm

Tcstr

Tfasb

Tcwt

Tipl

Tipl

Tcwt

Tcwt

Tcwt

Terf

Terf

Tetps

Tfbu

Tcyot

Tcwt

Tetps

Tetc

Tiwma

Tfasb

Tfasb

Tfasb

Tetc

Tetc

Tcwt

Tcwt

Tfbu

Tfbu

Tcwt

Tdsq

Tdsq

Tcwt

Tfra Tcwt

Tcwt

Tcwt

Tcwt

Tcwt

Tcwt

Tcstr

Tcstr

Tirs

Tcstr

Qrf

Qrf

Tsf

Qrf

Qrf

Qrf

Tesre

Qrf

Qrf

Qrf

Qrf

Qrf

Qrf

Kag

Kaghf

Kaghf

Kags

Kb

Kb

Kp

Kp

Kj

Kj

Kj

Qs Kj

Kj

Kj

Kj

Kj Kj

Kp

QTa

Qia

Tdsrp

Tdsrp

Tdsrp

Tdsrp

Tsgb

Tfbu Tsbu

Tdsrp

Tfbmb

Tfvt

Tfbmb

Qia

Qia

Tcwtu

Tiwm

Tiwm

Tiwm

Tfbmb

Qia1

TKbp

Qia2

Qia2

Qia2

Qia2

Qlj

Qia2

Qia2

Qia2

Qia2

Qia2

Qia2

Qia2

Qya

Qya

Qya

Qya2

Qya2

Qya2

Qya2

Qya2

Qya

Qya

Qya

Qya

Qya

Qya

Qlb

Qlb

Qlc

Qlb

Qlt

Qlt

Qlt

Qlt

Qlt

Qia2

Qia2

Qia1

Qia1

Qia1

Qia1

Qia1

Qlg

Qlg

Tcks

Tcrt

Tcrt

Tigr

Tigr

Tigr

Tigr

Tigr

Tigr

Tigr

Tigr

Tsbu

Tsbu

Tigr

Tcks

Tcks

Qia1

Qlu

Qia1

Qia1

Qia1

Qia1

Qia1

Qia1

Qia

Qoa

Qoa

Qoa

Qoa

Qoa

Qoa

Tcnr

Tcnr

Tcyot

Qoa

Qia

Qia

Qlu

Qlu

Qlu

Qlu

Qlu

Qlu

Qlu

Qlu

Qlu

Qlu

Qlu

Tcksu

Tesbr

Tetps

Tesbr

Teslm

Teslm

Tesbr

Tespc

Tespc

Tespc

Tim

Tim

Tesbr

Tcksu

Qlu

Qia

Qia

Qia

Qia

Qia

Qia

Qia

Qia

Qia

Qia

QTa

QTa

QTa

Qe

Qlb

Qlt

Qlt

Qlb

Qlb

Qlb

Qls

Qls

Qlc

Qlc

Qlc

Qlc

Qlc

Qlb Qlb

QTa

QTa

QTa

Qlu

QTa

Tcnr

Tcnr

Tcnr

Tcnr

QTa

Qlu

Qoa

Qoa

Qoa

Qya

Qya

Qya

Qya

Qya

Qya

Qya

Qya1 Qya1

Qya1

Qya1

Qya2

Qya2

Qya2

Qya2

Qya2

Qya2

Qya2

Qya2

Qya2

Qya2

Qya2

Qya1

Qya1

Qya1

Qya1

Qya1

Qya1

Qya1

Qya1

Qya1

Qya1

Qya1

Qya1

Qya1

Tfasb

Qya

Qya

Qya

TKbp

TKbp

TKbp

Tdds

Tdds

Tfdb

Tfdmt

Tim

Tim

TKbp

TKbp

Tdds

Tfacb

Tfacb

Tfacb

Tcbr

Tebr

Tcyot

Tcyot

Tesre

Tesre

Tcyot

Tcss

Tcbr

Tcwtu

Tcwtu

Tcwtu

Tcwtu

Tfbmb

Tfbmb

Tcnr

Tdsm

Tdsrp

Tdsrp

Tdsrp

Tdsrp

Tetps

Tetps

Tfbu

Tfbu

29°15'00''

29°07'30''

103°15'00'' 

3219

3221

3222

3224

3225

3226

3227

3224

3225

3226

3227

3228

3229

3231

3232

3233

3234

3235

3236

3238

3239

3241

3242

3243

3244

3245

3246

3247

3240000 m N

3234

3235

3236

3238

3239

3241

3242

3243

3244

3245

3246

3247

3240000 m N

3230000 m N

3228

3229

3231

3232

3233

3230000 m N

3220000 m N

3219

3221

3222

3220000 m N

660 659 000 m W

659

661 662 663 664 665 666 667 668 669

660000 m W 661 662 663 664 665 666 667 668 669 671 672 673 674 675 676 677 678 679

103°15'00''

103°22'30'' 

103°22'30''

29°15'00''

29°07'30''

20

13

19

2

3

4,5

8

7

1

18

6

21

22

14

16

15

25

11

9

23

26

17

24

12

27

10

10

15

15

15

65

10

10

30

10

5

5

5

5

5

5

5

5 5

10

10

80 80

10

10

10

10

10

20

10

10

10

15

5

5

10

10

10 15

25

25

33

10

25

25

30

35 15

15

15

15

15

15

10

10

10 20

20 5

5

5

5

5

5

10

2

25

5

15

15

20

20

20

20

20

20

20

20

20

30

30

35

35 35

35

40

25

30 30

30

20

10

10

20

20

30

30

10

10

40

5 5

5

5

5

5

5 15

15

15

15

15

15

15

15

15 15

15

15

15

15

15

15

15

15

15

10

10

10

20

5

5

5

5

5

65

15

15

15

55

15

15

15

5

5

35

80

60

50

40

40

25

25

25

25

25

25

25

5

5

5

5

10

25

35 35

35

25 25

25

25

25

25

70

20

20

30

10

10

10

10

10

10

10

10

10

10

80 50

10

20

20

20

20

20

20

20

20 20

20 20

20

20

10

10

20

20

20

20

20

20

20

20

20

5

5

20

20

40

40

50

40

5

5

35

70

30

30

30

30

35

20

20

20

20

20

20

25

25

25

25

25

45

25

25

25

25

25 25

25

15

15

15

15

25

30

25

25

25

25

10 10

10 55

10

10

15

15

15

15

15

5

5

5

5

5

10

10

10

20

20

20

20

25

25

15

30

15

10

10

10

20

20

20

40

25

10

10

10

10

10 10

10

10

5

25

25

40

10

10

25

25

25

10

10

10

10

10

15

15

15

15

25

50

30

30

20

35

10

10

10

10

10

10

10

10

5

5

5

5

5

10

10

5

Contact

Dike, leucocratic—Light colored, mostly rhyolite and rhyodacite

 porphyry

Dike, intermediate—Dark colored, mostly andesite and dacite

Fault—Dashed where approximately located; dotted where concealed

 

Mass movement sole and related faults—Dotted where concealed

 

Anticline

Syncline

Road, paved—Suitable for all vehicles

Road, service—Official use only

Trails

Dirt road—High clearance recommended

Strike and dip of bedding

Sample for age determination—Showing sample number keyed to

 results reported in rock descriptions

Inclined

Horizontal

50

MAP EXPLANATION

19

This map was produced under the partial auspices of the U.S. 

National Park Service (NPS). Cartography for roads and trails 

was provided by Geographic Information Specialists (GIS) at the 

NPS Park Headquarters. The geologic data come from a variety 

of sources and the map represents the work of several 

geologists from the U.S. Geological Survey (USGS), University 

of Texas at El Paso (UTEP), University of Texas at Austin (UTA) 

and Texas Tech University (TTU). All of the geology is primarily 

based on the author’s interpretation of ortho-rectified USGS 

color-infared photogrammetry. This facilitated a uniform 

locational accuracy of geologic features to within 2 m throughout the mapped area. Large parts of the map also benefited 

from field studies conducted by numerous geologists (see figure 

below). All of the surficial deposits (rocks of Quaternary age) 

have been studied to various degrees by Margaret Berry and 

Van Williams (both USGS). Dan Miggins (USGS and UTEP) 

provided age and petrographic data for specific sites over much 

of the area. Areas 1 and 2 – the author (USGS), areas 3, 4, and 5 

– Kenzie Turner and the author (both USGS), area 6 – Robert 

Scott, Lawrence Snee, and Kenzie Turner (all USGS), area 7 – 

Tom Lehman (UTA and TTU), area 8 – Robert Scott (USGS), area 

9 – Ric Page (USGS), and area 10 – Dan Barker (retired) and 

Robert Scott (USGS). Other parts of the map (photograph) have 

not been field checked. 

1

2

3

10

4

5

6

7 Photograph

Photograph

8

9

SUPPORT AND DATA SOURCES

Qya

Qya1

Qya2

Qrf

Qc

Qe

Qs

Qia

Qia1

Qia2

Qlb

Qlc

Qlg

Qlj

Qlu

Qls

Qlt

Qlp

Qoa

QTa

Tsgb

Tebr

Terf

Teeb

Alluvium, undivided (Holocene to latest Pleistocene)

Younger alluvium (Holocene)

Older alluvium (latest Pleistocene)

Rock fall deposits (Holocene)

Colluvium and colluvial fans (Holocene)

Eolian sand (Holocene)

Spring deposits (Pleistocene) 

Basalt source

Granitic source

Chisos Formation source

Javelina Formation source

Undifferentiated source

Sandstone source

Trachyte source

Pine Canyon Member of South Rim Formation source

Intermediate age alluvial deposits, undivided (late and middle Pleistocene)

Younger intermediate age alluvium (late Pleistocene)

Older intermediate age alluvium (middle Pleistocene)

Landslide deposits (Pleistocene)

Old alluvium (middle to early Pleistocene)

Extremely old alluvium (early Pleistocene and Pliocene)

Gabbro sill (Oligocene)

Breccia (Oligocene)

Rhyolite flow (Oligocene)

Explosion breccia (Oligocene)

Flows and intrusions of the eruptive and intrusive episodes (Oligocene and Eocene?)

LIST OF MAP UNITS

[Due to the addition of a shaded-relief base, colors on the map

may not exactly match colors in the List of Map Units]

Tfbmb

Tcbr

Tcwt

Tcksu

Tfra

Tcyot

Tckss

Tcss

Tfasb

Tfacb

Tcstr

Tcnr

Tcks

Tfbu

Tcl

Tcrt

Tsm

Tsi

TKbp

Kj

Kag

Kags

Kaghf

Kp

Kb

Bee Mountain Basalt Member (Oligocene)

Breccia facies (Eocene)

White tuff facies (Eocene)

Upper siltstone facies (Eocene)

Rhyolite ash flow (Eocene)

Yellow-orange tuffaceous sandstone facies (Eocene)

Tuffaceous sandstone facies (Eocene)

Undifferentiated sandstone facies (Eocene)

Lacustrine facies (Eocene)

Rhyolite tuff facies (Eocene)

Older sills (Eocene)

Mafic sill

Intermediate sill

Marine seaway deposits (Paleocene and Cretaceous)

Black Peaks Formation (lower Paleocene and Upper Cretaceous)

Javelina Formation (Upper Cretaceous)

Aguja Formation (Upper Cretaceous)

Metamorphosed sandstone and quartzite facies

Hornfels facies

Pen Formation (Upper Cretaceous)

Boquillas Formation (Upper Cretaceous)

Ash Spring Basalt Member (Eocene)

Alamo Creek Basalt Member (Eocene)

Sandstone, tuff, and rhyolite facies (Eocene)

Nodular rhyolite tuff facies (Eocene)

Lower siltstone facies (Eocene)

Basalt flows, undifferentiated (Eocene)

Surficial deposits

South Rim Formation (Oligocene)

Lost Mine Member

Boot Rock member (informal)

Pine Canyon Rhyolite Member

Mafic intrusions of Pine Canyon caldera and Dominguez Mountain (Oligocene)

Nugent Mountain intrusion (Oligocene)

Panther laccolith (Oligocene)

Rough Spring laccolith (Oligocene)

Rhyolite intrusions of Sierra Quemada (Oligocene)

Tuff and conglomerate (Oligocene)

Undifferentiated basalt sills (Oligocene)

Mafic dikes and sills (Oligocene)

Dominguez Mountain flows (Oligocene? and Eocene?)

Chisos Formation and equivalent volcanic rocks (Oligocene and Eocene)

Upper white tuff facies (Oligocene)

Vitric tuff (Oligocene)

Rocks equivalent to South Rim Formation (Oligocene)

Altered parts of Ward Mountain pluton (Oligocene)

Intermediate to mafic intrusion (Oligocene)

Rhyolite porphyry dikes and silles (Oligocene)

Dominguez Mountain dike swarms (Oligocene)

Sierra Quemada dike complex (Oligocene)

Rhyolite dikes of Sierra Quemada (Oligocene)

Felsic sill (Oligocene)

Ward Mountain pluton (Oligocene)

Granite (Oligocene)

Young basalt flows at Dominguez Mountain (Oligocene)

Teslm

Tesbr

Tespc

Tesre

Tiwma

Tii

Tdsrp

Tdds

Tdsq

Tdr

Tsf

Tiwm

Tigr

Tfdb

Tim

Tinm

Tipl

Tirs

Tetc

Tsbu

Tdsm

Tfdmt

Tcwtu

Tfvt

Tir

Tetps Trachyte flows of Punta de la Sierra (Oligocene)

Qya

Qia

Qoa

QTa

Qya1

Qya2

Qia1

Qia2

Qrf

Qs

Qc Qe

Tcbr

Tcwtu

Tcwt

Tcksu

Tcyot

Tckss Tcss

Tcstr

Tcnr

Tcl

Tcrt

Tcks

TKbp

Kj

Kag

Kp

Kb

Kags Kaghf

Qlb Qlc Qlg Qlj Qlu Qls Qlt Qlp

Tetps

Tfdb

Tfdmt

Tebr

Tfvt

Tfbmb

Tfra

Tfasb Tfacb Tfbu

Tsm Tsi

Tsgb

Tdsrp

Tsbu

Tdds

Tdsm

Tdsq Tdr Tsf

Tiwma Tii

Tiwm Tigr Tim Tinm Tipl Tirs Tir

Terf

Teslm

Tesbr

Tespc

Tetc

Teeb

Tesre

Marine seaway

Older sills

Chisos Formation and temporally equivalent rocks

SEDIMENTARY ROCKS LANDSLIDE DEPOSITS VOLCANIC ROCKS DIKES AND SILLS STOCKS AND PLUTONS

CORRELATION OF MAP UNITS

[Due to the addition of a shaded-relief base, colors on the map

may not exactly match colors in the Correlation of Map Units]

Eruptive episode

Intrusive episode

Surficial deposits

Holocene

Pleistocene

Pliocene

Oligocene

Eocene

Paleocene

Upper

Cretaceous

QUATERNARY

NEOGENE

PALEOGENE

CRETACEOUS

U.S. DEPARTMENT OF THE INTERIOR

U.S. GEOLOGICAL SURVEY

SCIENTIFIC INVESTIGATIONS MAP 3140

Pamphlet accompanies map

Prepared in cooperation with the

U.S. NATIONAL PARK SERVICE

Any use of trade names is for descriptive purposes only 

and does not imply endorsement by the U.S. Government

This map was produced on request, directly from 

digital files, on an electronic plotter

For sale by U.S. Geological Survey Information Services

Box 25286, Federal Center, Denver, CO 80225

1-888-ASK-USGS

ArcInfo coverages and a PDF for this map are available at 

http://pubs.usgs.gov/sim/3140/

Suggested citation:

Bohannon, R.G., 2011, Geologic map of the Chisos Mountains,

Big Bend National Park, Texas: U.S. Geological Survey

Scientific Investigations Map 3140, scale 1:50,000.

GEOLOGIC MAP OF THE CHISOS MOUNTAINS, BIG BEND NATIONAL PARK, TEXAS

By

Robert G. Bohannon

2011

CONVERSION FACTORS

Multiply By To obtain

inches (in.) 2.54 centimeters (cm)

feet (ft) 0.3048 meters (m)

miles (mi) 1.609 kilometers (km)

See “Support and Data Sources”

Digital map database prepared

by Paco R. Van Sistine

Editing and digital cartography by

Gayle M. Dumonceaux

Denver Publishing Service Center

Manuscript approved for

publication November 5, 2010

Base from U.S. Geological Survey

Digital Elevation Model 10-meter

digital data

Cultural data from digital files provided

by U.S. National Park Service

Universal Transverse Mercator

projection, zone 13

1984 World Geodetic System

TEXAS

LOCATION MAP

SCALE 1: 50 000

1 1/ 2 0 1 2 3 4 MILES

1 .5 0 1 2 3 4 5 KILOMETERS

TRUE NORTH

MAGNETIC NORTH

7°

APPROXIMATE MEAN

DECLINATION, 2010