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Geologic Framework, Structure, and Hydrogeologic Characteristics of the Knippa Gap area in Eastern Uvalde and Western Medina Counties, Texas

ByA.K. Clark, D.E. Pedraza, and R.R. Morris

2013

Suggested citation: Clark, A.K., Pedraza, D.E., andMorris, R.R., 2013, Geologic framework, structure,and hydrogeologic characteristics of the KnippaGap area in eastern Uvalde and western MedinaCounties, Texas: U.S. Geological Survey ScientificInvestigations Report 2013–5149, 35 p., 1 pl., http://pubs.usgs.gov/sir/2013/5149/.

Base from U.S. Geological Survey digital data, various scalesUniversal Transverse Mercator projection, zone 14North American Datum of 1983

Information regarding water resources in Texas isavailable at http://tx.usgs.gov

Prepared in cooperation with theU.S. Army Corps of Engineers

U.S. Department of the InteriorU.S. Geological Survey

Scientific Investigations Report 2013–5149Mapped hydrogeologic units and cross sections, 2013—Sheet 1 of 1

Clark, A.K., Pedraza, D.E., and Morris, R.R., 2013, Geologic framework, structure, and hydrogeologiccharacteristics of the Knippa Gap area in eastern Uvalde and western Medina Counties, Texas

T E X A S

Study area

UVALDECOUNTY

MEDINACOUNTY

Trinity aquifer

San Antonio segment of the Edwards aquiferBALCONES FAULT

ZONE

BEXARCOUNTY

0 5 10 KILOMETERS2.5 7.5

7.52.5 10 MILES50

EXPLANATION

System

Terti

ary

Uppe

r con

finin

g un

it to

Edw

ards

aqu

ifer

Edw

ards

aqui

fer

Non

e

Uppe

r Cre

tace

ous

Low

er

Cret

aceo

us

Maverick BasinGroup or Formation

Devils RiverGroup or Formation

Hydrologic Unit

KiKi

Escondido Formation

Anacacho Limestone

Austin Group

Eagle Ford Group

Buda Limestone

Del Rio Clay

Devils River Formation

Escondido Formation

Anacacho Limestone

Austin Group

Eagle Ford Group

Buda Limestone

Del Rio Clay

Salmon Peak Formation

Kes

Kan

Kau

Kef

Kbu

Kdr

Kdrv

Tei

Kes

Kan

Kau

Kef

Kbu

Kdr

Ksa

Study boundary

Contact—Dashed where inferred

Fault—Dashed where inferred

Fracture

Facies change

City boundary

Line of section

Inferred structural dip

Well and well identifier (appendix 1)

Indio Formation

Igne

ous

Igne

ous

A A'

YP–69–43–106

Structural trough of the

Knippa Gap area

Appro

ximate

width

of

the str

uctura

l troug

h

Appro

ximate

width

of

the str

uctura

l troug

h

YP–69–36–800YP–69–36–9xx

YP–69–51–602

YP–69–52–403

YP–69-50-309YP–69–44–704a

YP–69–44–806a

YP–69–45–8xx

YP–69–43–804YP–69–45–701a

YP–69–43–605

YP–69–43–606

YP–69–43–403YP–69–43–409

YP–69–43–103

YP–69–43–106YP–69–43–202 YP–69–43–301b

TD–69–38–905a

YP–69–36–602

YP–69–37–402

YP–69–51–606

YP–69-42-902

YP–69–44–902

YP–69–44–808a

YP–69-42-911

YP–69–46–102

YP–69–36–904

YP–69–52–7xx

YP–69–52–9xx

YP–69–51–408

YP–69–51–6xxb

YP–69–51–1xxcYP–69–52–201

YP–69–51–301aYP–69–51–1xxa

YP–69–53–2xxYP–69–51–104

TD–69–45–101TD–69–45–105

TD–69–45–108TD–69–45–109TD–69–45–102

TD–69–45–103

TD–69–45–104

TD–69–45–203

TD–69–45–201

TD–69–45–202

TD–69–45–301

TD–69–45–303

TD–69–45–302

YP–69–45–405

YP–69–45–406

YP–69–45–402YP–69–45–501

YP–69–45–504

YP–69–45–4xx

YP–69–45–802

YP–69–45–704

YP–69–45–701b

YP–69–45–702

YP–69–45–703

YP–69–45–7xx

YP–69–44–9xx

YP–69–44–806bYP–69–44–807

YP–69–44–808b

YP–69–44–703

YP–69–44–704b

YP–69–44–601YP–69–44–502YP–69–44–503

YP–69–44–5xx

YP–69–44–4xxa

YP–69–44–4xxb

YP–69–44–402YP–69–44–401YP–69–44–404

YP–69–44–406

YP–69–44–405

YP–69–44–407

YP–69–44–305

YP–69–44–303

YP–69–44–301

YP–69–44–302

YP–69–44–304

YP–69–44–203

YP–69–44–201

YP–69–44–204

YP–69–44–109YP–69–44–110

YP–69–44–106

YP–69–44–102

YP–69–44–101

YP–69–44–103

YP–69–44–105

YP–69–43–307

YP–69–43–308YP–69–43–302

YP–69–43–303

YP–69–43–306

YP–69–43–305

YP–69–43–301a

YP–69–43–205YP–69–43–3xxc

YP–69–43–105

YP–69–43–108

YP–69–43–109

YP–69–43–4xxa

YP–69–43–4xxbYP–69–43–4xxc

YP–69–43–4xxd

YP–69–43–4xxeYP–69–43–4xxf

YP–69–43–408YP–69–43–410

YP–69–43–402

YP–69-42-606

YP–69–43–502

YP–69–43–503

YP–69–43–601

YP–69–43–603

YP–69–43–6xx

YP–69-42-9xx

YP–69–43–7xxa

YP–69–43–7xxb

YP–69–43–7xxc

YP–69–43–7xxd

YP–69–43–803

YP–69–43–802

YP–69–43–916

YP–69–43–902

YP–69–43–912YP–69–43–905

YP–69–43–908

YP–69–43–909

YP–69–43–917

TD–69–46–101

TD–69–46–102

TD–69–46–1xx

TD–69–46–6xx

TD–69–38–905b

TD–69–46–404

TD–69–46–405

TD–69–38–1xxb

TD–69–46–8xxb

TD–69–38–101

TD–69–38–103

TD–68–31–1xxaTD–68–31–1xxbTD–68–31–1xxc

TD–69–46–8xxa

TD–69–38–1xxa

YP–69–43–9xx

YP–69–44–8xx

YP–69–45–5xx

YP–69–45–400

YP–69–43–3xxa

YP–69–51–102

YP–69–51–1xxb

YP–69–51–205YP–69–51–204

YP–69–51–203

YP–69–51–301b

YP–69–51–2xxaYP–69–51–2xxb

YP–69–51–2xxc

YP–69–51–2xxd

YP–69–51–2xxe

YP–69–51–5xx

YP–69–51–6xxa

YP–69–51–6xxc

YP–69–44–408

YP–69–43–2xx

Ki

Tei

KiKi

Kau

KefKau

Kbu

KefKdr

Kbu

Kdr

KbuKdr

Ksa

Kef

Kdr KauKdr

KiKauKiKdr

KsaKefKef

Ki

Kbu

Kau

KefKdr Kdr Kbu

Ki

Kbu

KiKau

Kbu

KiKbu

Ksa Kbu

Kdr Kan

Kau

KiKef

Ki

KanKef

Ki

Kbu

Kau

KdrKan

Ksa

Kau

Ki

Kef

Kbu

Kbu

Kef Kbu

KiKi

Kan

KsaKbu

Kef

KbuKbu Ki

KiKdr

Kbu

Kau

Ksa

Ki

Kdr

Kef

KiKef

Kbu

KauKefKau

Kef

Kbu

Kef

Kdr

Kdr

Kdr

Kbu KanKbu

Kbu Kdr

KdrKdrKbu

Kes

Kef

Kdr

KbuKdrv

Kan

Ksa Kdr

Kau

Kes

Kau KanKef

Kau

KdrvKan

Kau

Kau

Kbu

Kef

Kan

Kau

Kan

Kdrv

Kan

Kan

Kau

Kef

Kbu

Kau

Kau

Kau

KanKanKau Kau

KauKefKbu

KefKau Kef

KbuKbu

Kau

KbuKbu

Kau

Ki Kdr

Kau

Kau

Kbu

Kbu

Kef

Kdr

Kdr

Kdr

KauKbu

Kbu

KefKbu

Kef

Kdrv

Kdr

KbuKbu KbuKef

Kau

KdrKbu

Kdrv

Kbu

Kau

Kdrv

KdrKbuKef

Kdrv

Kdrv

Kdr

Kbu

Kan

A

A'

B'

B

ME

DIN

A

CO

UN

TY

UVA

LD

EC

OU

NT

Y

Uvalde

Sabinal

Knippa

99°16'15"

99°24'

99°31'45"

99°39'30"

99°47'15"

29°28'45"

29°21'

29°13'15"

99°16'15"

99°24'

99°31'45"

99°39'30"

99°47'15"

29°28'45"

29°21'

29°13'15"

Ki

Ki

Ki

Kef

Ki

Ki

Ki

Ki

Ki

Ki

Ki

Ki

Ki

Ki

Ki

Ki

KiKbu

Ki

Ksa

Ksa

Kbu

Ki

Ki

Ki

Ki

Kan

Kan

Kan

Kan

Kan

Kbu

Kbu

GULF

OF ME

XICO

Base modified from U.S. Geological Survey 1:24,000-scale digital dataUniversal Transverse Mercator projection, zone 14North American Datum of 1983

Kdr

Qle

Qle

Qle

Qle

T-Qu

T-Qu

T-Qu

T-Qu

T-Qu

T-Qu

T-Qu

Sabinal

Uvalde

Knippa

29°28'45"

29°21'

29°13'15"

99°16'15"99°24'99°31'45"99°39'30"99°47'15"

0 5 102.5 7.5 MILES

0 5 102.5 7.5 KILOMETERS

MED

INA

CO

UN

TYU

VALD

E C

OU

NTY

A

A'

B'

B

A A'Study boundaryLine of sectionFault—Dashed where inferredFractureRelay ramp—InferredUvalde Salient—Inferred

System Epoch

Quat

erna

ry

Leon

a aq

uife

rN

one

Quat

erna

ryor

Ter

tiary

Plio

cene

Plei

stoc

ene

FormationHydrologic

Unit

Qle Leona Formation

Uvalde GravelT-Qu

EXPLANATION

Uvalde Salient

Relay ramp

Structural trough of the

Knippa gap area

Approx

imate w

idth of

the str

uctura

l trough

T-Qu

Base modified from U.S. Geological Survey 1:24,000-scale digital dataUniversal Transverse Mercator projection, zone 14North American Datum of 1983

Frio River

Nueces River

Seco Creek

Creek

Sabinal River

River

MedinaLake

Medina

Hondo

KINNEY COUNTYUVALDE COUNTY

MEDINA COUNTY

Brackettville

KnippaUvalde

SabinalHondo

Western storage unit

Western Medinastorage unit

Eastern M

edina

storage u

nit

99°00'99°30'100°00'100°30'

29°30'

29°15'

0 10 20 MILES5 15

0 10 20 KILOMETERS5 15

EXPLANATION

San Antonio segment of the Edwards aquifer recharge zone in Kinney, Medina, and Uvalde Counties, Texas (George and others, 2011)

Edwards aquifer outcrop

Edwards aquifer subcrop

Approximate downdip limit of the freshwater zone in the Edwards aquifer (A.L. Schultz, written commun., 2000)

Study area boundary

Rio Grande

Base modified from U.S. Geological Survey 1:250,000-scale digital dataUniversal Transverse Mercator projection, zone 14North American Datum of 1983

Frio River

Leona River

C. Storage units and unconfined and confined zones of the Edwards aquifer in Kinney, Medina, and Uvalde Counties, Texas.

E. Cross section B–B'

D. Cross section A–A'

B. Location of the Leona Formation and Uvalde gravels in and around the study area.

A. Mapped hydrogeology and faulting

BEN

D IN

SECT

ION

BEN

D IN

SECT

ION

BEN

D IN

SECT

ION

BEN

D IN

SECT

ION

BEN

D IN

SECT

ION

BEN

D IN

SECT

ION

BEN

D IN

SECT

ION

BEN

D IN

SECT

ION

YP–6

9–52

–201

YP–6

9–45

–701

a

YP–6

9–44

–902

YP–6

9–44

–806

a

YP–6

9–51

–606

YP–6

9–52

–403

YP–6

9–45

–5xx

YP–6

9–46

–102

YP–6

9–51

–6xx

b

TD–6

9–38

–905

aTD

–69–

38–9

05b

2,0000 4,000 6,000 FEET

VERTICAL SCALE GREATLY EXAGGERATED

-850

-800

-750

-700

-650

-600

-550

-500

-450

-400

-350

-300

-250

-200

-150

-100

-50

NAVD 88

50

100

150

200

250

300

350

400

450

500

550

600

650

700

750

800

850

900

950

1,000

1,050

1,100

1,150FEET

FB19

FB16 FB16a FB15 FB14 FB20

SOUTHWEST NORTHEAST

FB19a

A A'

Approximate width of the structural trough

SECT

ION

B–B

'

NAVD 88, North American Vertical Datum of 1988

Hydrologic unit Upper confining unit to Edwards aquifer Edwards aquifer

Trinity aquifer

Land surface

Fault—Dashed where inferred. Arrow shows relative movement

Well

Well identifier (appendix 1)

Fault block identifier

YP–69–43–106

FB01

EXPLANATION

BEN

D IN

SECT

ION

BEN

D IN

SECT

ION

BEN

D IN

SECT

ION

BEN

D IN

SECT

ION

BEN

D IN

SECT

ION

YP–6

9–53

–2xx

YP–6

9–45

–8xx

YP–6

9–45

–400

YP–6

9–45

–5xx

YP–6

9–36

–9xx

YP–6

9–36

–904

YP–6

9–36

–602

-1,100

-1,050

-1,000

-950

-900

-850

-800

-750

-700

-650

-600

-550

-500

-450

-400

-350

-300

-250

-200

-150

-100

-50

50

100

150

200

250

300

350

400

450

500

550

600

650

700

750

800

850

900

950

1,000

1,050

1,100

1,150

1,200FEET

NAVD 88

FB02

FB04FB03 FB05 FB07 FB08 FB09 FB11 FB12 FB14 FB15 FB16 FB17 FB18

FB01

FB10 FB13FB06

NORTHWEST SOUTHEAST

2,0000 4,000 6,000 FEET

VERTICAL SCALE GREATLY EXAGGERATED

B B'

SECT

ION

A–A

'

NAVD 88, North American Vertical Datum of 1988