WATER-RESOURCES INVESTIGATIONS REPORT 00–4195Hydrogeologic subdivisions of the Edwards aquifer outcrop—PLATE 1

Small, T.A., and Clark, A.K., 2000, Geologic framework and hydrogeologiccharacteristics of the Edwards aquifer outcrop, Medina County, Texas

U.S. DEPARTMENT OF THE INTERIORU.S. GEOLOGICAL SURVEY

IN COOPERATION WITH THEEDWARDS AQUIFER AUTHORITY

MAP SHOWING HYDROGEOLOGIC SUBDIVISIONS OF THE EDWARDS AQUIFEROUTCROP, MEDINA COUNTY, TEXAS

ByTed A. Small and Allan K. Clark

2000

Base modified from U.S. GeologicalSurvey 1:24,000 quadranglesUniversal Transverse Mercator ProjectionZone 14

0 1 2 3 4 MILES

Seco

Creek

Hondo

Creek

Hondo

Creek

Verde

Cre

ek

Geronimo

Creek

MEDINA

RIVER

MED

INA

LAK

E

MED

INA

LAK

E

Bull

Creek

County Road

211

CountyRoad

131

FM 462

Sta

te

173

FM 1796

FM 462

FM

462

Sta

te 1

73

State

16

Park Road 37

County

Cou

nty

Roa

d

Road

251

252

FM

1283

1283FM

County

Road

271

2615

County Road

County Road 351

Cou

nty

Roa

d

265

Woodard

Cave

fault

UD

UD

Verde Creekfault

UD

UD

Woodard

Cave

fault

UD

D U

D U

UD

UD

UD

UD

UD

UD

UD

UD

D U

Seco Creek

fault

Vandenburg

School

fault

UD

UD

UD

Medina

Lake

fault

UD

Parker

Creek

fault

DU

DU

UD

Lincoln

fault

Haby

Crossing

fault

Diversion

Lake

fault

UD

UD

UD

UD

UD

UD

UD

UD

UD

UD

UD

UD

UD

UD

DU

UD

UD

UD

UD

UD

UD

DU

UD

DU

UD

UD

Rugh Sinkhole

Woodard Cave

Ney Cave

Boehme's Cave

Haby Bat Cave

Bear Springs

Sheep Springs

Cypress Springs

Indian Springs

Moccasin Springs

29o37'30"

99o22'30"

29o30'

99o07'30"99o15'

98o52'30"

99o

29o37'30"

99o22'30"

99o15' 99o07'30"

99o

98o52'30"

29o37'30"

29o30'

FACIES CHANGE

PRIMARY FAULT—U, upthrown side; D, downthrown side

U

D

U

DINFERRED FAULT—U, upthrown side; D, downthrown side�

SPRING

CAVE

Hill Country State Natural Area

TEXAS

Study area

SAN ANTONIO

UVALDE COUNTY

BANDERA COUNTY

BEXAR COUNTY

Study area San AntonioLOCATION MAP

MEDINA COUNTY

Balcones fault zone

III LEACHED AND COLLAPSED MEMBERS, UNDIVIDED

IV REGIONAL DENSE MEMBER

V GRAINSTONE MEMBER

VI KIRSCHBERG EVAPORITE MEMBER

VII DOLOMITIC MEMBER

VIII BASAL NODULAR MEMBER

UPPER MEMBER OF THE GLEN ROSELIMESTONE (LOWER CONFINING UNIT)

DE

VIL

S R

IVE

R F

OR

MAT

ION

PE

RS

ON

FO

RM

ATIO

N

ED

WA

RD

S G

RO

UP

KA

INE

R F

OR

MAT

ION

ED

WA

RD

S A

QU

IFE

R

TRINITYAQUIFER

I GEORGETOWN FORMATION

II CYCLIC AND MARINE MEMBERS, UNDIVIDED (NOT EXPOSED IN STUDY AREA)

UP

PE

R C

ON

FIN

ING

UN

IT

EXPLANATION

DEL RIO CLAY

BUDA LIMESTONE

EAGLE FORD GROUP

AUSTIN GROUP

HYDROGEOLOGIC SUBDIVISIONS I–VIII— Modified from Maclay and Small (1976)

ALLUVIUM

LEONA FORMATION

ESCONDIDO FORMATION

ANACACHO LIMESTONE

QU

ATE

RN

AR

YU

PP

ER

CR

ETA

CE

OU

SLO

WE

R C

RE

TAC

EO

US

FO

RT

TE

RR

ET

T F

M.

SE

GO

VIA

FM

.

NOTE: Segovia Formation not exposed in study area.

Koenig Creek

Geology modified on the basis ofadditional field work in Medina County.�