Geology and Ground- Water Resources of the Deer Lodge Valley

Geology

and

Ground-

Water

Resources

of

the

Deer

Lodge

Valley

Montana

GEOLOGICAL

SURVEY

WATER-SUPPLY

PAPER

1862

Prepared

in

cooperation

with

the

Montana

Bureau

of

Mines

and

Geology,

Butte,

Montana

jeology

and

Ground-

Vater

Resources

of

he

Deer

Lodge

Valley

Montana

R.

L.

KONIZESKI,

R.

G.

McMURTREY,

and

ALEX

BRIETKRIETZ

Ith

a

section

on

GRAVIMETRIC

SURVEY

E.

A.

CREMER

III

EOLOGICAL

SURVEY

WATER-SUPPLY

PAPER

1862

repared

in

cooperation

with

the

Ionian

a

Bureau

of

Mines

and

' eology,

Butte,

Montana

-»-

-ssrra

RE

CEIVE

I

DEC

3

1968

NTITED

STATES

GOVERNMENT

PRINTING

OFFICE,

WASHINGTON

:

1968

UNITED

STATES DEPARTMENT

OF

THE

INTERIOR

STEWART

L.

UDALL,

Secretary

GEOLOGICAL

SURVEY

William

T.

Pecora,

Director

Library

of

Congress

catalog-card

No.

GS

68-227

For

sale

by

the

Superintendent

of

Documents,

U.S.

Government

Printing

Office

Washington,

D.C.

20402

CONTENTS

Page

Abstract____

______________________________________________________

1

Introduction-

_____________________________________________________

2

Purpose

and

scope.____________________________________________

2

Acknowledgments.

____________________________________________

2

4

Methods.____________________________________________________

4

Well-numbering

system._______________________________________

5

Geography__

___________________________________________________

7

Location

and

extent

of

valley..--__-___-___-_.________-__------_

7

Topography-

----------___-__-_________________.___________-_-

7

Drainage._

___________________________________________________

9

Climate.

_____________________________________________________

9

History

and

culture____________________________________________

11

Agriculture.__________________________________________________

11

Geology.-_---_--__---_-_-_.___________________________________-_-

12

Regional

stratigraphy._________________________________________

12

Intravalley

stratigraphy____-______-_______-____-____-___-_-_-_-

13

Tertiary

volcanic

rocks...__________________________________

13

Tertiary

sedimentary

deposits...____________________________

13

Quaternary

moraine

deposits_____._____________-___-_-_--_-_

20

Quaternary

alluvium___-______.______._____-__----_--_---

22

Regional

structure.--_-__-___-___.__________________---__--_--_

24

Intravalley

structure...______-_-________.________-__-_-___-----

24

Tertiary

history-__--_--_____-___________________-______-_-----

25

Quaternary

history.

___-_____---__-_-_-__._._-_-_-__-_---_-_--_

27

Gravimetric

survey,

by

E.

A.

Cremer

III__.__-_____-_._--_---------

27

Methods._______________________-_______-_____-__--_---_--_--

28

Reduction

of

data.

_-_--__-___-__--_-___--__--_-_-___-_--------

28

Results_____-________-____________________-_--__-_-_------_-

28

Summary.

__-__-_--________-_____-__________-_-_------_-------

30

Ground

water.--___-__--_-_______________-____-_--_--__-_---------

30

Definition

of

selected

hydrologic

terms.

____-_-________--_--_-_---

30

Principles

of

occurrence..__-_-______.-__.____-__----___--------

31

Hydrologic

properties

of

water-bearing

materials_____________-_---

32

9

Multiple-well

tests_____-_.__-_-_-_-_._-__-----_.---------

32

Single-well

tests__________-_______-_-_____-----_-----_---_-

34

Specific

capacity

_

_____.__--____---_--_-_--_-_--__---_-----

34

Summary

of

hydrologic

properties.

_____________._-_---------

35

Water

table

and

movement

of

ground

water-

______-_-_-----------

37

Fluctuations

of

water

level-

______-_________-_--__------_-------

39

Recharge-

----__-_________-_-___-__------__-_____-_---_-------

42

Discharge.__-_____-__.__-_______-______-.__--_----_----------

43

Present

development.___.-__--_.---__------_-_.----_--_--------

46

Potential

development-

___-___-.-_-_._____-_--.----------------

46

Summary

and

conclusions____________-___-___-__---------------

47

Selected

references___-________^__________-___-__--__-_--__---------

48

Index__

-_____-_________________.________________-__-_---_---------

51

in

IV

CONTENTS

ILLUSTRATIONS

Page

PLATE

1.

Geohydrologic

map

of

Deer

Lodge

Valley,

Mont_

______

-In

pocket

2.

Residual

gravity

map

and

sections

of

southern

Deer

Lodge

Valley.-_----_-_______---__-______--__--_____.-_-In

pocket

FIGURE

1.

Map

showing

cooperative

ground-water

investigations

in

Montana,

1955-67_________________________________

3

2.

Sketch

showing

well-numbering

system.__________________

6

3.

Outline

of

study

area

and

principal

topographic

and

drain-

age

features..-.-_______--_.-___-___--______--__-__-_

8

4.

Graphs

showing

average

monthly

temperature

and

precipi-

tation

at

Deer

Lodge,

1931-66___-------_---_---------

10

5.

Diagrammatic

section

across

east

side

of

Deer

Lodge

Valley

showing

environmental

types

of

Pliocene

sediments

and

their

east-west

distribution

___________________________

17

6.

Photograph

showing

Pliocene

channel deposits

at

the

Galen

gravel

pit,

sec.

36,

T.

6

N.,

R.

11

W_._________________

18

7.

Diagrammatic

section

showing

topographic,

age,

and

struc-

tural

relationships

of

older

moraine,

high

terrace,

recent

erosion

surface,

and

faultline(?)

scarp

south

of

Rock

Creek.

20

8.

Hydrographs

showing

the

effect

of

location,

depth

to

water,

and

geologic

setting

on

seasonal

fluctuations

of

the

water

level-.-.___________________________________________

40

TABLES

TABLE

1.

Report

on

samples

of

gravel

from

Deer

Lodge

Valley,

Mont-

2.

Aquifer

test

data._____________________________________

3.

Coefficient

of

transmissibility

values

estimated

from

specific

capacities.-.-

-

_________-___-___---_-_-_--_--------_-

4.

Monthly

water

supply

of

the

Deer

Lodge

Valley

in

acre-feet

for the

period

June-September

1961

-------------------

5.

Miscellaneous

streamflow

measurements,

Deer

Lodge

Valley,

1961-.---__--_-____-__--___-__-___--__---_-___--__-

Page

23

33

35

44

45

GEOLOGY

AND

GROUND-WATER RESOURCES

OF

THE

DEER

LODGE

VALLEY,

MONTANA

By

R.

L.

KONIZESKI,

R.

G.

MCMUBTKEY,

and

ALEX

BBIETKRIETZ

ABSTRACT

The

Deer

Lodge

Valley

is

a

basin

trending

north-south

within

Powell,

Deer

Lodge,

and

Silver

Bow

Counties

in

west-central

Montana,

near

the

center

of

the

Northern

Rocky

Mountains

physiographic

province.

It

trends

northward

between

a

group

of

relatively

low,

rounded

mountains

to

the

east

and

the

higher,

more

rugged

Flint

Creek

Range

to the

west

The

Clark

Fork

and

its

tributaries

drain

the

valley

in

a

northerly

direction.

The

climate

is

semiarid

and

is

characterized

by

long

cold

winters

and

short

cool

summers.

Agriculture

and

ore

refining

are

the

principal industries.

Both

are

dependent

on

large

amounts

of

water.

The

principal

topographic

features

are

a

broad

lowland,

the

Clark

Fork

flood

plain,

bordered

by

low

fringing

terraces

that

are

in

turn

bordered

by

broad,

high

terraces,

which

slope

gently

upward

to

the

mountains.

The

high

terraces

have

been

mostly

obscured

in

the

south

end

of

the

valley

by

erosion

and

by

recent

deposition

of

great

coalescent

fans

radiating

outward

from

the

mouths

of

various

tributary

canyons.

The

mountains

east

of

the

Deer

Lodge

Valley

are

formed

mostly

of

Cretaceous

sedimentary

and

volcanic rocks

and

a

great

core

of

Upper

Cretaceous

to

lower

Tertiary

granitic

rocks;

those

west

of

the

valley

are

formed

of

Precambrian

to

Cretaceous

sedimentary

rocks

and

a

core

of

lower

Tertiary

granitic

rocks.

Field

relationships,

gravimetric data,

and

seismic

data

indicate

that

the

valley

is

a

deep

graben,

which

formed

in

early

Tertiary

time

after

emplacement

of

the

Boulder

and

Philipsburg

batholiths.

During

the

Tertiary

Period

the

valley

was

partly

filled

to

a

maximum

depth

of

more

than

5,500

feet

with

erosional

detritus

that

came

from

the

surrounding

mountains

and

was

interbedded

with

minor

amounts

of

volcanic

ejecta. This

material

accumulated

in

a

great

variety

of

local

environments. Consequently

the

resultant

deposits

are

of

extremely

variable

lithology

in

lateral

and

vertical

sequence.

The

deposits

grade

from

unconsolidated

to

well-cemented

and

from

clay

to

boulder-sized

aggregates.

Throughout

most

of

the

area

the

strata

dip gently

towards

the

valley

axis,

but

along

the

western

margins

of

the

valley

they

dip

steeply

into

the

mountains.

In

late

Pliocene

or

early

Pleistocene

the

Tertiary

strata

were

eroded

to

a

nearly

regular,

valleywide

surface.

In

the

western

part

of

the

valley

the

erosion

surface

was

thinly

mantled

by

glacial

debris

from

the

Flint

Creek

Range.

Still

later,

probably

during

several

interglacial

intervals,

the

Clark

Fork

and

its

tributaries

entrenched

themselves

in

the

Tertiary

strata

to

an

average

depth

of

about

150

feet.

The

resultant

erosional

features

were

further

modified

by

Wisconsin

to

Recent

glaciofiuvial

deposition.

1

2

GROUND-WATER

RESOURCES,

DEER

LODGE

VALLEY,

MONT.

Three east-west

cross

.sections

and

a

corrected

gravity

map

were

drawn

for

the

valley.

They

indicate

a

maximum

depth

of

fill

of

more

than

5,500

feet

in

the

southern

part.

Depths

decrease

to

the

north

to

approximately

2,300

feet

near

the

town

of

Deer

Lodge.

The

principal

source

of

ground

water

in

the

Deer

Lodge

Valley is

the

upper

few

hundred

feet

of

unconsolidated

valley

fill.

Most

of

the

wells

tapping

these

deposits

range

in

depth

from

a

few

feet

to

250

feet.

Water

levels

range

from

somewhat

above

land

surface (in

flowing

wells)

to

about

150

feet

below.

Yields

of

the

wells

range

from

a

few

gallons

per

minute

to

1,000

gallons

per

minute.

Generally,

wells

having

the highest

yields

are

on

the

flood

plain

of

the

Clark

Fork

or

the

coalescent

fans

of

Warm

Springs

and

Mill

Creeks.

Discharge

of

ground

water

by

seepage

into

streams,

by

evapotranspiration,

and

by

pumping

from

wells

causes

a

gradual

lowering

of

the

water

table.

Each

spring

and

early

summer,

seepage

of

water

from

irrigation

and

streams

and

infiltration

of

water

from

snowmelt

and

precipitation

replenish

the

ground-water

reservoir.

Seasonal

fluctuation

of

the

water

table

generally

is

less

than

10

feet.

The

small

yearly

water

table

fluctuation

indicates

that

recharge

about

balances

discharge

from

the

ground-water

reservoir.

A

generalized

representation

of

the

water

table

in

part

of

the

valley

indicates

that

ground

water

moves

toward

the

Clark

Fork

from

the

east

and

west,

but

in

detail the

slope

of

the

water

table

and

the direction

of

movement

of

the

water

vary throughout

the

valley.

In

the

southwestern

part

movement

of

ground

water

is

generally

northeast

at

a

gradient

of

about

50

feet

per

mile

with

components

of

flow

towards

the

tributary

streams.

In

other

parts

ground

water

moves

toward

the

Clark

Fork

under

a

gradient

of

70

feet

per

mile

or

more.

The

rate

of

movement

of

ground

water

in

the

valley

is

generally

less

than

3

feet

per

day.

INTRODUCTION

PURPOSE

AND

SCOPE

The

study

of

the

geology

and

ground-water

resources

of

the

Deer

Lodge

Valley

is

part

of

a

cooperative

program

with

the

Montana

Bureau

of

Mines

and

Geology

to

evaluate

the

ground-water

resources

of Montana

(fig.

1).

The

study

was

beg

to

in

July

1957

and

the

field-

work

was

completed

in

1962.

It

was

made

in

order

to

determine

(1)

the

character,

thickness,

and

extent

of

the

water-bearing

materials,

(2)

the

source,

occurrence,

and direction

of

movement

of

the

ground

water,

(3)

the

quantity

and

availability

of

the

ground

water,

(4)

the

seasonal,

annual,

and

long-term

changes

in

ground-water

storage,

and

(5)

areas

from

which

substantial

supplies

of

underground

water

can

be

obtained.

ACKNOWLEDGMENTS

The

writers

wish

to

express

their

appreciation

to

all

who

aided

this

study.

Thanks

are

extended

to

those

individuals

who

willingly

sup-

plied

information

about

their

wells,

consented

to

the

use

of

their

wells

for

water-level

measurements,

and

allowed

admittance

to

their

land.

Well

drillers,

especially

C.

F.

Wroble,

were

most

helpful

in

furnish-

ing

well

logs

and

other

useful

information.

The

fallowing

organiza-

INTRODUCTION

g

13

8,

o

T

4

GROUND-WATER

RESOURCES,

DEER

LODGE

VALLEY,

MONT.

tions

contributed

to

the

progress

of

the

investigation:

Anaconda

Copper

Mining

Co.,

Mount

Haggin

Land

and

Livestock

Co.,

Montana

State

Prison,

Montana

State

Hospital,

Montana

Power

Co.,

and

the

U.S.

Soil

Conservation

Service.

During

the

summers

of

1899-1900

Prof.

Earl

Douglass

of

Montana

State

University

prospected

for

fossil

vertebrates

and

studied

the

Cenozoic

geology

of

the

Deer

Lodge

Valley.

The

results

of

his work

were

published

in

1901

and

have

formed

the

basis

for

most

later

descriptions

of

Cenozoic

stratigraphy

in

the

area.

Subsequent

geologic

and

hydrologic investigations

include

a

discussion

of

the

regional

stra-

tigraphy

of

Billingsley

(1913),

a

description

of

the

coal

resources

of

the

valley

by

Pardee

(1913),

a

generalized

description

of

the

geol-

ogy

and

topography

of

the

area

by

Campbell

(1915),

and

a discus-

sion

of

the

Cenozoic

history

of

the

valley by

Alden

(1927).

Perry

(1933)

included

a

brief

description

of

the

ground-water

resources

of

the

valley

in

a

report

on

the

possibilities

of

ground-water

supply

for

certain

towns

and

cities

of

Montana.

Pardee

(1951)

attrib-

uted

the

origin

of

the

valley

to

structural

deformation.

Alden

(1953)

discussed

glacial

deposits

along

the

western

margins

of

the

valley.

Konizeski

(1957)

described

Pliocene

ecological

relationships

within

the

valley.

Mutch

(1960)

outlined

the

glacial

chronology

of

the

Flint

Creek

Range,

and

Csejetey

(1962)

presented

a

detailed

discussion

on

the

stratigraphic

relationships

of

outcropping

Tertiary

strata at

the

base

of

the

range

near

Anaconda.

Smedes

(1962)

vol-

canic

rocks

near

Anaconda

with

the

Tertiary

Lowland

Creek

Vol-

canics

near

Butte.

Preliminary

reports

on

the

water

resources

of

the

area

have

been

published

(Konizeski

and

others,

1961,

1962).

Numerous

mine

reports

include

references

to

the

area.

METHODS

The

geology

was

mapped

on

aerial photographs.

The

geologic

map

includes

the

valley

and

a

border

zone,

which

shows

the

relationship

of

INTRODUCTION

5

the

valley

fill

to

the

consolidated

rocks

of

the

surrounding

mountains.

A

gravimetric

survey

was

made

during

the

1961

field

season.

The

data

were

used

to

interpret

the

approximate

basement

profile

of

the

valley,

structural

relationships,

and the

approximate depth

of

valley

fill.

From

a

well

inventory

made

during

the

field

seasons

of

1957

and

1960,

data

were

compiled

for

270

wells

and

springs

in

the

area,

and

a

network

of

84

observations

wells

was

selected

to

determine

water-

table

fluctuations.

Data

from

the

inventory

and

water-level

measure-

ments

in

the

observation

wells

are

on

open

file

at

the

U.S.

Geological

Survey

office

in

Helena,

Mont.

The

altitude

of

the

water

surface

in

129

wells,

measured

in

September

1960,

was

used

to

make

a

map

showing

contours

on

the

water

table.

The

hydrologic

properties

of

water-bear-

ing

materials

were

determined

by

17

single-well

and

three

multiple-

well

aquifer

tests.

WELL-NUMBERING

SYSTEM

The

wells

described

in

this

report

are

assigned

numbers

that

are

based

on

their

location

within

the

system

of

land

subdivision

used

by

the

U.S.

Bureau

of

Land

Management.

The

well

number

shows

the

location

of

the

well

by

quadrant,

township,

range,

section,

and

position

within

the

section.

This

method

of

well

numbering

is

shown

in

figure

2.

The

first

letter

of

the

well

number

gives

the

quadrant

of

the

meridian

and

base-line

system

in

which

the

well

is

located.

The

first

numeral

indicates

the

township,

the

second

the

range, and

the

third

the

section

in

which

the

well

is

located.

Lowercase

letters

that

follow

the

section

number

show

the

location

of

the

well

within

the

quarter

section

(160-

acre

tract)

and

the

quarter-quarter

section

(40-acre

tract).

These

sub-

divisions

are

designated

"a,"

"b,"

"c,"

and

"d"

in

a

counterclockwise

direction,

beginning

in

the

northeast

quadrant.

If

two

or

more

wells

are

within the

same

40-acre

tract,

consecutive

digits

beginning

with

1

are

added

to

the

well

number.

For

example,

well

B4-10-36ab3

is

in

the

NW1/4NE1/4

sec.

36,

T.

4

N.,

E.

1

W.

and

is

the

third

well

inven-

toried

in

that

tract.

Springs

are

numbered

in

the

same

manner.

293-420

O 68-

6

GROUND-WATER

RESOURCES,

DEER

LODGE

VALLEY,

MONT.

Ranges West

Ranges

East

12 10

BASE

LINE

-Well

number

B4-10-36ab

R.

10

W.

6

7

18

19

30

31

5

8

17

20

29

32

4

9

16

21

28

33

3

10

15

22

27

34

2

11

14

23

26

35

1

12

13

24'

25

"

36

FIGURE

2. Well-numbering

system.

.TOPOGRAPHY

7

GEOGRAPHY

LOCATION

AND

EXTENT

OF

VALLEY

The

Deer

Lodge

Valley

includes

about

300

square

miles

within

Powell,

Deer

Lodge,

and

Silver

Bow

Counties.

It

extends

northward

from

near

Gregson

to

a

relatively

narrow

place

near

Garrison

(fig.

3).

The

term

"valley"

as

used

in

this

report

includes

the

area

of

relatively

low

altitude

and

low

relief

that

is

bounded

on

the

east

by

a

group

of

low,

rounded

mountains

and

on

the

west

by

the

rugged

Flint

Creek

Range.

TOPOGRAPHY

The

Deer

Lodge

Valley

is

a

basin

trending

north-south

near

the

center

of

the

Northern

Rocky

Mountains

physiographic

province

(Femneman,

1931,

p.

223).

The Continental

Divide

is

roughly

parallel

to

and

5

to

15

miles

east

of

the

valley

(fig.

3).

The

mountains

in

this

area

are

locally

known

as

the

Deer

Lodge

Mountains

and

are

mostly

below

8,000

feet,

but

a

few

attain

altitudes

of

more

than

8,500

feet.

The

topography

is

generally

low

and

rolling

with

tree-covered

slopes

and

great

open

parks.

However,

a

deeply

glaciated

area

of

high

local

relief

exists

east

of

Deer

Lodge

around

Thunderbolt,

Cliff,

Negro,

and

Bison

Mountains.

The

Flint

Creek

Range

is

a

deeply

dissected

dome

about

28

miles

long

in

the

north-south

direction

by

20

miles

wide.

Much

of

the

area

is

more

than

8,000

feet

in

altitude,

and

several

peaks

are

more

than

9,000

feet.

Mount

Powell,

the

highest

peak

in

the

range,

attains

an

alti-

tude

of

10,171

feet.

Many

deep

gorges

are

separated

by

knife-edged

divides

and

depths

on

the

order

of

2,000

feet

or

more

are

not

unusual.

U-shaped

canyons,

aretes,

cirques,

ice

scour,

and

other

indications

of

glaciation

are

much

in

evidence.

The

valley

topography

is

dominated

by

great

terraces,

designated

here

as

high

terraces,

that

slope

gently

downward

from

the

mountains

and

end

in

abrupt

scarps

above

low

terraces

bordering

the

broad

flood

plain

of

the

Clark

Fork.

The

slope

of

the high

terraces

toward

the

Clark

Fork

ranges

from

4°

or

5°

near

the

mountains

to

less

than

1°

near

the

low

terraces.

The

high

terraces

range

in

altitude

from

5,700

feet

to

4,600

feet.

In

the northwestern

part

of

the

valley

they

are

about

125

feet

above

the

low

terraces

and

have

a

maximum

width

of nearly

5

miles.

The

high

terraces

narrow

and

become

progressively

lower

towards

the

south

end

of

the

valley.

Throughout

the

valley

their

average

width

is

about

4

miles

and

they

have

been

deeply

dissected.

The

flood

plains

of

the

tributary

streams

coalesce

and

merge

with

the

low

terrace

along

the

Clark

Fork.

8

GROUND-WATER

RESOURCES,

DEER

LODGE

VALLEY,

MONT.

113°00' 112°30'

FIGURE

3. Study

area

and

principal

topographic

and

drainage

features.

In

the

southwestern

part

of

the

valley all

these

several

topographic

features

merge

and

tend

to

lose

their

identities

because

of

dissection

of

the

terraces

and

emplacement

of

great

coalescent

fans.

However,

iso-

lated remnants

of

the high

terraces

occur

about

600

feet

above

the

valley

floor.

Most

of

the major

tributary

valleys

west

of

the Clark

Fork

are

modified by

great

Wisconsin

moraines.

GEOGRAPHY

9

DRAINAGE

Above

its

junction

with

the

Little

Blackfoot

Kiver

the

Clark

Fork

and

its

tributaries

drain

about

1,200

square

miles.

Because

the

area

east

of

the

valley

is

generally

semiarid,

streams

from

there

are

rela-

tively

small.

Conversely

because

the

Flint

Creek

Kange

is

generally

subhumid,

the

streams

draining

that

area

are

relatively

large.

Two

perennial

tributaries

enter

the

valley

from

the

east;

seven,

from

the

west;

and

two,

from

the

south.

Numerous

intermittent

tributaries

drain

the

lower

mountain

slopes

on

both

sides

of

the

valley.

The

Clark

Fork

turns

sharply

to

the

northwest

near

Garrison

and

flows

for

many

miles

through

a

series

of

deep

gorges.

The

Clark

Fork

enters

the

south

end

of

the

valley

through

a

narrow

gorge

at

an

altitude

of about

5,100

feet

and

leaves

the

valley

at

an

alti-

tude

of about

4,400

feet.

Between

Gregson

and

Warm

Springs

the

aver-

age

gradient

is

about

26

feet

per

mile

and

between

Warm

Springs

and

Garrison

the

average

gradient

is

about

8

feet

per

mile.

The

mean

an-

nual

flow

of

the

Clark

Fork

at

Deer

Lodge

has

been

estimated

(Frank

Stermitz,

oral

commun.,

1961)

at

about

250±75

cfs

(cubic

feet

per

second).

In

its

upper

(southern)

reaches,

the

stream

is

held

against

the

eastern

wall

of

the

valley

by

the

great

coalescent

fans

of

Mill,

Warm

Springs,

and

Lost

Creeks.

In

its

middle

and

lower reaches

its

flood

plain

is

about

1

mile

wide

and

lies

slightly

east

of

the

valley

axis.

The

stream's

meandering

course

is

marked

by

numerous

cutoff

oxbows,

sloughs,

and

marshes

wherein

grow

a

variety

of

hydrophytic

and

riparian

plants.

Tributaries

to

the

Clark

Fork

flow

from

consolidated

rocks

in

the

mountains

onto

unconsolidated

fill

in

the

valley

where

much

of

their

flow

is

lost

by

seepage.

Most

of

the

remaining

flow

is

diverted

for

irri-

gation

and

industrial

use.

CLIMATE

The

Deer

Lodge

Valley

has

a

semiarid

climate

characterized

by

long

cold

winters,

short

cool

summers,

low

precipitation,

and

moderate

winds.

The

average

monthly

temperature

and

precipitation

at

Deer

Lodge

are

shown

in

figure

4.

The

highest

recorded

temperature

at

Deer

Lodge

during

the

years

1931-66

was

100°

F,

and

the

lowest

tempera-

ture

was

39°

F

below

zero.

Changes

from

midday

temperatures

of

more

than

80°

F

to

nighttime

temperatures

of

less

than

50°

F

are

common

in

July.

The

length

of

the

growing

season

is

highly

variable

but

averages

about

95

days.

September

5

is

the

average

date

of

the

first

killing

frost

and

June

5,

the

last

killing

frost.

The

highest

recorded

yearly

precipitation

was

14.67

inches

in

1938;

the

lowest

was

5.91

inches

in

1935.

Approximately

50

percent

of

the

10

GROUND-WATER

RESOURCES,

DEER

LODGE

VALLEY,

MONT.

TEMPERATURE,

IN

DEGREES

FAHRENHEIT

H-

ro

co

->

ui

cri

3

O

O O

O

1

Average

annual

temperature

-

~

^

-

:

.:':-^

MAMJ

J

ASO

AVERAGE

MONTHLY

TEMPERATURE

2.0

1.8

1.6

LU

o

1.4

?

1.2

g

i-

Q.

0

0.8

LU

ce

Q.

0.6

0.4

0.2

n

-

i

''''

:

.

'-:>

1

-

;

': ;

'.

:.;;.;.;

:

~

' ' ' '.'.

'-\'

' :.' ' :'

;

'

'..

: :

"

: : ;

'

, :

'

'.

...

'

.

.'.:

.;

;

>.:

. :

.:

.-.:

:

"

: ;

MAMJJASON

AVERAGE

MONTHLY

PRECIPITATION

FIGURE

4. Average

monthly

temperature

and

precipitation

at

Deer

Lodge,

1931-66.

(From

U.S.

Weather Bureau

records.)

GEOGRAPHY

11

average

annual

precipitation

is

during

May,

June,

and

July;

nearly

75

percent

occurs

from

April

through

September.

At

Deer

Lodge

the

periods

1936

through

1951

and

1954

through

1959

generally

had

above

average

precipitation;

the

other

periods generally

had

below

average

precipitation.

HISTORY

AND

CULTURE

The

Deer

Lodge Valley

derived

its

name

from

an

Indian

expression

meaning

white-tailed

deer's

lodge.

It

was

so

called

because

of

large

numbers of

white-tailed

deer

in

the

valley

and

because

of

a

cone-shaped

mound

at

Warm

Springs.

This

mound,

about

40

feet

high,

was

formed

by

a

thermal

spring.

Steam

issuing

from

the

mound

reminded

the

Indians

of

smoke

rising

from

an

Indian

lodge.

One

of

the

earliest

settlers

in the

area

was

John

Francis

Grant,

who

in

1855

raised

cattle

in the

valley.

In

the

early

1860's

successive

groups

of

gold

prospectors

passed

through

on

their

way

to

the

mining

settle-

ments.

Many

returned

to

the

village

of

Cottonwood

(Deer

Lodge)

and

the

surrounding

area

to

become

tradesmen

and

ranchers.

A

Federal

penitentiary

was

built

in

1871,

and

it

became

the

State

prison

in

1873.

In

1878

the

first

college

in

Montana

was

opened

at

Deer

Lodge.

In

1883,

Marcus

Daly,

founder

of

the

copper

mining

industry

at

Butte,

located

a

smelter

near

Warm

Springs

Creek

because

of

the

favorable

water

supply.

The

smelter encouraged

immigration

and

settlements

sprang

up

around

the

site.

Anaconda

is

one

early

settlement

that

remains.

In

1960

the

population

of

Anaconda

was

12,054

and

that

of

Deer

Lodge

was

4,651.

The

patients

and

staff

at

hospitals

in

Warm

Springs

and

Galen

number

more

than

800

and

200

respectively.

Opportunity

is

a

small

town

of

several

hundred

inhabitants.

AGRICULTURE

Seasonal

shortage

of

water

supply

is

a

major

consideration

for

successful

farming

in

the

valley.

Most

irrigated

crops

are

raised

on

the

Clark

Fork

flood

plain,

the

low

terraces,

and

the

high

terraces

on

the

west side

of

the

valley.

The

high

terraces

on

the

east

side

of

the

valley

are mostly

dry-farmed.

Hay

is

the major

irrigated

crop

and

is

used

locally

to

support

the

livestock

industry.

Potatoes

are

the

largest

cash

crop

in

the

valley,

the

area

being

one

of

the

largest

producers

of

potato

seed

in

Montana.

Other

crops

are wheat,

barley,

and

corn.

12

GROUND-WATER

RESOURCES, DEER

LODGE

VALLEY,

MONT.

GEOLOGY

REGIONAL

STRATIGRAPHY

The

consolidated rocks

marginal

to

and

underlying

the

Deer

Lodge

Valley

are,

for

convenience,

referred

to

in

this

report

as

basement

rocks

(pi.

1).

They

are

described

briefly to

implement

later

discussions

of

the

geology

of

the

valley

fill

and

the

ground-water

regimen.

The

in-

formation

is

mostly

from detailed

descriptions

by

others,

particularly

Knopf

(1953);

Weeks

and

Klepper

(1954); Chapman,

Gottfried,

and

Waring

(1955);

Mutch

(1960);

Euppel

(1957,

1961);

and

Csejetey

(1962).

The

highlands

marginal

to

the

Deer

Lodge Valley

are

formed

on

a

great

variety

of

rocks

that

range

from

Precambrian

to

early

or

mid-

dle

Tertiary

age.

The

Flint

Creek

Range

is

formed

of

a

variety

of

structurally

deformed

Precambrian

metamorphic

rocks

and

Paleozoic

and

Mesozoic

sedimentary

rocks

that

have

been

intruded

by

granitic

masses.

One

intrusive

mass,

the

Philipsburg

batholith,

has

been

tenta-

tively

dated

as

middle

Eocene

(?).

In

general,

the

sedimentary

rocks

crop

out

in

a

narrow

belt

around

the

eastern

flanks

of

the

range.

The

oldest

(Precambrian)

rocks

are

farthest

from

the

valley,

and

the

youngest

(Mesozoic)

rocks

are

nearest

to

the

valley.

The

Precambrian

rocks

consist

of

about

25,000

feet

of

fine-grained

clastic

rocks;

the

Paleozoic

rocks consist

of

about

6,000

feet

of

limestone,

dolomite,

and

some

quartzite;

and

the

Mesozoic

rocks

consist

of

about

15,000

feet

of

fine-grained

clastic

rocks.

More

than

2,800

feet

of

welded

tuff,

described

by

Smedes

(1962,

p.

260)

as

a

rapidly

accumulated

unit

of

the Lowland

Creek

Volcanics,

crops

out

intermittently

along

the

base

of

the

range

northward

from

the

south

side

of

Warm

Springs

Creek

to

Spring

Gulch.

Baadsgaard,

Folinsbee,

and

Lispson

(1961,

p.

697)

obtained

a

potassium-argon

date

of

49

million

years

(middle

Eocene

age)

from

biotite

in

a

dike,

which

Smedes

(1962,

p.

264)

describes

as

part

of

a

system

of

dikes

that

cut

the

welded

tuff

unit

west

of

Butte.

Smedes

assigned

a

late

Oligocene

age

to the tuff

because

of

(1)

a

small

flora

collected

by

Csejetey

(1962)

from

associated

sedimentary

rocks

in

the

Warm

Springs

Creek

and

Lost

Creek

areas

and

(2)

the

fact

that

the

volcanic

rocks

are

uncon-

formably

overlain

by

lower

Miocene

deposits

west

and

southwest

of

Butte

(Wood,

1936,

p.

12-13).

The

Lowland

Creek

Volcanics

was

re-

assigned

to the

Eocene

on

the

basis

of

a

potassium-argon

determination

of

48

to

50

million

years

(Smedes

and

Thomas,

1965).

The

marginal

highlands

to

the

east

and south

of

the

valley

are

formed

on

about

15,000

feet

of

Lower

to

middle

Cretaceous

sedimen-

tary

and

volcanic

rocks.

These

rocks

have

been

intruded

by

Upper

GEOLOGY

13

Cretaceous

to

lower

Tertiary

(Boulder

batholith)

granitic

rocks,

which

are

in

turn

overlain

by

patches

of

lower

to

middle

Tertiary

volcanic

rocks.

The

Cretaceous

sedimentary

and

volcanic

rocks

con-

sist

of

about

11,000

feet

of

fine-grained

clastic

rocks

that

are

overlain

by

about

4,000

feet

of

andesitic

pyroclastic

rocks

and

flows.

The

lower

to

middle

Tertiary

volcanic

rocks

are

mostly

siliceous

tuffs

and

flows.

In

general,

the

highlands

northeast

of

the

valley

are

formed

on

andes-

itic

rocks;

the

highlands

southeast

of

the

valley

are

formed

on

granitic

rocks;

and

the

highlands

near

the

southern

end

of

the

valley

are

formed

on

siliceous

volcanic

rocks

and

granitic

rocks.

INTRAVALLEY

STRATIGRAPHY

TERTIARY

VOLCANIC

ROCKS

An

elongate

belt

of rocks

near

the

axis

of

the

valley

has

been

de-

scribed

as

the

Garrison

Vent

(Mutch,

1960).

It

trends

N.

30°

W,

from

Mullan

Creek

past

the

northern

boundary

of

the

study

area

and

is

about

2

miles

wide

by

several

miles

long.

These volcanic

rocks

are

rela-

tively

resistant

to

weathering

and

form

an

erosional

remnant

of

the

high

terrace.

Around

the southeastern

margin

of

this

high

terrace

remnant

they

intrude

metamorphosed

Kootenai

Formation

and

Colo-

rado

Shale.

The

volcanic

rocks

are

bordered

locally

to

the

southwest

by

Miocene

sediments

and

to

the

southeast

by

sediments

of

probably

Miocene

age.

The

contacts

are

poorly

or

not

at

all

exposed,

but

some

of

the

sediments

of

probably

Miocene

age

contain

locally

derived

volcanic

detritus.

The

vent

is

believed

to

be

of

Tertiary,

probably

pre-Miocene

age.

TERTIARY

SEDIMENTARY

DEPOSITS

The

Deer

Lodge

Valley

is

partly

filled

with

a

great

mass

of

ma-

terial

(valley

fill)

eroded

from

rocks

in

the

surrounding

mountains

and

with

smaller

amounts

of

volcanic

ejecta.

The

valley

fill

consists

mostly

of

unconsolidated

to

semiconsolidated

Tertiary

sedimentary

deposits,

but

some

consolidated

Teritary

sediments

are

exposed

around

the

western

margins

of

the

valley,

and

others

probably

occur

at

depth.

All

are

referred

to

here

as

Tertiary

strata.

Tertiary

strata

underlie

the

high

terraces

and

are

elsewhere

over-

lain

by

Quaternary

alluvium.

More

than

2,000

feet

of

section

is

exposed

over

about

120

square

miles

or

two-fifths of

the

valley.

A

series

of

gravimetric

profiles

(p.

29)

indicate

a

maximum

thickness

of

more

than

5,500

feet

of

valley

fill

on

a

basement

profile

of

moderate

relief.

An

average

of

about

25

feet

of

this

material

is

believed

to

be

Quarter-

nary

alluvium;

the

remainder,

Tertiary

strata.

A

Montana

Power

Co.

293-420

O 68 3

14

GROUND-WATER

RESOURCES,

DEER

LODGE

VALLEY,

MONT.

test

well

(State

1-1-22)

about

5

miles

southwest

of

Deer

Lodge

in

sec.

22,

T.

T

N.,

R.

10

W.

penetrated

2,495

feet

of

Tertiary

strata

and

bot-

tomed

in

tuff(

?)

at

2,536

feet.

The

upper

300

feet

of

section

is

sand

and

gravel.

The

remainder,

except

for

some

pebble

conglomerate

be-

tween

450

and

860

feet

and

cobbles(?)

between

820

and

860

feet,

is

interbedded

limestone, shale,

sandstone,

and

grit.

The

elastics

are

mostly

quartz,

calcareous

detritus,

and

various

percentages

of

benton-

itic

clay.

About

a

tenth

of

the total

section,

or

235

feet,

is

made

up

of

18

beds

of

limestone

and

two

of

dolomite.

This

calcareous

material

was

apparently

derived

from

Paleozoic

and

Mesozoic

limestone

for-

mations,

which

once

may

have

mantled

the

Boulder

batholith

and

still

partly

mantle

the

Philipsburg

batholith

and

associated

stocks

in the

Flint

Creek

Range.

Granitic

debris

from

either

the

Boulder

or

Philipsburg

batholith

is

abundant

between

820-860,

1,505-1,515,

and

2,115-2,130

feet.

The

upper

300

feet

of

sand

and

gravel

penetrated

in

this

well

is

mid-

dle

Pliocene.

Because

of

the

ubiquitous

presence

of

bentonite

in

the

deeper

deposits,

the

abrupt

change

of

lithology

at

300

feet,

and

the

granitic

detritus,

the

underlying

strata

are

assumed

to

be

older

than

Pliocene

and

younger

than

the

middle

Eocene

(?)

batholiths.

At

least

1,600

feet

of

mostly

coarse-grained

Tertiary strata

of

ex-

tremely

varied

lithology

crops

out

intermittently

along

the

base

of

the

Flint

Creek

Range

from

the

vicinity

of Warm

Springs

Creek

northward

to

Robinson

Creek

(pi.

1).

In

some

places

the

strata

over-

lie

Cretaceous

rocks;

in

other

places

they

apparently

underlie

Plio-

cene

deposits.

Some

beds

are

almost

entirely

volcanic-rich

erosional

debris

derived

from

associated

Lowland

Creek

Volcanics;

some

beds

are

bentonitic;

others

contain

various

percentages

of

erosional

detritus

from

Precambrian,

Paleozoic

and

Mesozoic

sedimentary

rocks

and

middle

Eocene(?)

granitic

rocks.

The

rocks

range

from

fissile

shale

to

poorly

sorted

boulder

conglomerate

with

boulders

as

large

as

4

feet

in

diameter.

Some

of

the

beds

are

so

well

indurated

as

to

fracture

across

the

grains;

some

are

semiconsolidated

and

others

are

uncon-

solidated.

Because

the

beds

have

been

described

elsewhere

in

consider-

able

detail

(Mutch,

1960,

and

Csejetey,

1962)

they

are

discussed

here

only

briefly.

The

northernmost

exposure

of

the

1,600

feet

of

Tertiary

strata

is

a

small

patch

of

cemented

colluvium

formed

of

and

overyling

Cretac-

eous

rocks

at

the

mouth

of

Robinson

Creek

canyon

in

sec.

5,

T.

7

N.,

R.

10

W.

More

than

200

feet

of

bentonitic

conglomerate

and

arkose

crops

out

farther

to

the

south

between

Racetrack

Creek

and

Dempsey

Creek.

From

clay

lenses

in the

conglomerate

and

arkose

(SW%

sec.

f,

T.

6

N.,

R.

10

W.)

were

collected specimens

of

Equisteum,

sp.

(Greta-

GEOLOGY

15

ceous

to

early

Tertiary)

and

Alnus

microdentoides

(identification

by

Erling

Dorf,

Princeton Univ.).

Both

species

occur

in

Oligocene(?)

beds

in

the

Missoula

Valley

about

75

miles

to

the

northwest.

A.

micro-

dentoides

is

known

from

only

the

two

localities.

About

250

feet

of

lime-cemented

conglomerate

and

intercalated

lenses

of

sand

crop

out

between

Spring

Gulch

and

Modesty

Creek.

The

poorly

exposed

basal

beds

in

sec.

6,

T.

5

N.,

R.

10

W.

are

mostly

erosional

debris

from

the

underlying

volcanic

rocks,

but

the

upper

beds

are

entirely

erosional

debris

from

Paleozoic

rocks

immediately

to

the

west.

These conglomerates

have

been

tentatively

described as

Eocene

(Mutch,

1960)

and

Miocene

or

Pliocene

(Csejetey,

1962).

From

volcanic-rich,

granite-bearing

sediments

intercalated

within

the

welded

tuff

south

of

Lost

Creek

in

sec.

25,

T,

5

K,

R.

11

W.,

Cse-

jetey

(1962)

has

collected specimens

of

five

species

of

fossil

plants.

All

are

common

to

the

volcanic-rich

beds

in

the

Missoula

Valley

which

were

originally

described

by

Douglass

(1901,

p.

4,

5)

as

"doubtfully

Oligocene."

On

the

basis

of

these

relationships

Erling

Dorf

(in

Cse-

jetey,

1962)

interpreted

the

Anaconda

flora

as

"probably

of

Late

Oli-

gocene

age,

or

possibly

slightly

younger,

i.e.

early

Miocene."

Douglass

did

not

discuss

the

evidence

on

which

he

based

his

original

tentative

age

designation

of

beds

in

the

Missoula

Valley.

However,

Jennings

(1920,

p. 388),

after

discussing

the

relationships

of

the

small

Missoula

Valley

flora

of

15

species

with

the

not

yet

satisfactorily

dated

Florissant

flora

of

115

species,

concluded

that

"I

can

see

no

reason

for

not

accepting

Douglass'

claim

that

the

beds

* * *

are

of

Oligocene

age."

The

much

larger

Florissant

flora

was

not

con-

clusively

dated

until

many

years

later

after

numerous

studies

had

been

made

and

other

stratigraphically

definitive

fossils

had

been

found

(MacGintie,

1953,

p.

1-198).

If

the

questionable

Missoula

Valley

Oligocene

date

is

accepted

as

valid,

two

formidable

weaknesses

still

remain

in

assigning

a

correla-

tive

age

to

the

1,600

feet

of

Tertiary

strata

in

the

Deer

Lodge

Valley.

First,

these

beds

contain

a

small

flora

that

ranges

from

Cretaceous

to

middle

or

late

Tertiary.

None

of

the

species

are

known

to

be

restricted

to

the

time

interval

in

question.

It

could

be

argued,

there-

fore,

that

the

specific

duplication

of

the

Missoula

and

Deer

Lodge

floras

is

simply

a

reflection

of

similar

environments

rather

than

strati-

graphic

correlation.

The

second

weakness

is

that

the

radiometric

dates

of

B'aadsgaard

and

others

indicate

that

the

Lowland

Creek

Volcanics

and,

therefore,

the

intercalated

plant

beds

are

Eocene.

The

distribution

and

extremely

varied

lithology

of

the

beds

may

relate

to

rapid

deposition

in

a

wide

variety

of

unstable

environments

along

the

base

of

the

ancestral

Flint

Creek

Range.

However,

without

16

GROUND-WATER

RESOURCES,

DEER

LODGE

VALLEY,

MONT.

stratigraphically

definitive

evidence

it

is

impossible

to

know

whether

deposition

of

the

1,600

feet

of

strata

took

place

almost contemporane-

ously

during

a

relatively

short

orogenic

interval

or

whether

these

beds

interfinger with

or

grade

into

the

coarse

Pliocene

and

Miocene

aggre-

gates

elsewhere

in

the

valley.

The

latter

would

indicate

deposition

over

a

much

longer

interval.

Because

of

the

above

considerations,

it

is

apparent

that

their

age

remains

an

open

question.

About

350

feet

of

well-bedded,

well-consolidated

to

unconsolidated

fluvial

clay,

silt,

sand,

and

pebble

conglomerate

of

early

Miocene

age

have

been

measured

in

various

outcrops

on

the

west side

of

the

Deer

Lodge

Valley

north

of

Mullan

Creek.

However,

because

of

local

deformation

and

talus

cover,

definite

correlation

of

most

of

the

indi-

vidual

sections

was

not

possible.

The

sediments

are

of

variable

com-

position

but

consist

mostly

of

well-rounded

grains

of

quartzite

and

granitic

rocks.

Some

of

them,

near

the

Garrison

Vent,

include

sub-

angular

fragments

of

locally

derived

volcanic

debris.

Metamorphism

is

not

apparent

in

the

Miocene

sediments,

although

it

is

evident

in

the

underlying

Cretaceous

rocks.

Because

of

the

above

relationships the

sediments

are

believed

to

be

younger

than

the

vent.

An

early

Miocene

vertebrate

fauna

(Konizeski,

1957;

Wood

and

Konizeski,

1965)

has

been

collected

from

these

sediments.

North

of

Willow

Creek,

interbedded silt,

sand,

and

conglomerate

of

early

Miocene

age

is

overlain

by

more

than

100

feet

of

bentonitic-rich

lacustrine

clay

and

silt

of

middle

or perhaps

late

Miocene

age

(Pardee,

1951,

p.

81-82).

A

small

patch

of

semi-indurated

sand

and

conglomer-

ate

at

the

head

of

Johnson's

Gulch

on

the

east

side

of

the

valley

has

been

mapped

as

Miocene(?)

(Konizeski,

1957,

p.

137).

Two

small

patches

of

lacustrine

deposits

of

probably

Miocene

age

occur

near

the

northeastern

margins

of

the

valley.

One

of

them

in

the

NE

1

^

sec.

8,

T.

7

N.,

R.

8

W.

is

plastered

on

Cretaceous

volcanic

rocks

at

an

alti-

tude

of

5,700

feet,

or

about

the

maximum

altitude

of

the

high

terrace

and

1,200

feet

above

the

Clark

Fork.

The

deposit

consists

of

a

basal,

volcanic-rich

conglomerate

overlain

by

interbedded

silt,

sand,

and

some

volcanic

ash.

These

sediments

are

well

bedded,

strike

about

N.

10°

E.,

and

because

of

primary

slumping,

dip

into the

valley

at

about

20°.

More

than

300

feet

of

unconsolidated

to

semiconsolidated

middle

Pliocene

sediments

underlies

most

of

the

high

terraces

on

both

sides

of

the

valley.

Along

the

eastern

margins

of

the

valley

they

overlap

gran-

itic

and

volcanic

basement

rocks;

typical

exposures

occur

near

the

head

of

Perkins

Gulch

in

sec.

16,

T.

5

N.,

E.

9

W.

In

the

northwestern

part

of

the

valley

they

uncoiiformably

overlie

lower

Miocene

sedi-

ments.

Typical

exposures

occur

in

the

high

terrace

scarp

along

Mullan

Creek

in

sec.

25,

T.

8

N.,

R.

10

W.

In

the southwestern

part

of

the

val-

GEOLOGY

17

ley

the

Pliocene

sediments

are

apparently faulted

against

and

overlie

the

lower

or

middle

Tertiary

beds

(fig.

5).

The

Pliocene

sediments

are

generally

well

bedded

and

usually

retain

their

primary

orientation

of

a

few

degrees

towards

the

valley

axis

and

to

the

north.

They

consist

of

several

depositional

types,

which

grade

into

and

interfinger

with

each

other.

Included

are

colluvial

deposits

that

grade

into

coarsely

bedded

piedmont

fans

of

grit

and

coarse

sand

which,

in

turn,

interfinger

with

lamellar

flood-plain

deposits

of

fine

sand,

silt,

and

clay.

In

the

central

parts

of

the

valley

the

Pliocene

deposits

commonly

consist

of

interbedded

channel

gravel

and

sand

(fig.

5).

The

channel

deposits

extend

towards

the

mouths

of

various

tributary

canyons;

for

example,

from

the

vicinity

of

Deer

Lodge

towards

the

mouths

of

Peterson

and

Cottonwood

Creeks.

The

distribution

of

these

depositional

types

of

Pliocene

sediments

is

not

exposed

in

any

single

or

continuous

series

of

outcrops.

The

colluvium

and

channel

deposits

are mostly

covered

by

Quaternary

alluvium.

However,

Pliocene

colluvium

is

exposed

near

the

heads

of

several

of

the

east

valley

draws,

particularly

in

Perkins

and

Woodard

Gulches.

Fan

and

flood-plain

deposits

crop

out

along

the

high

terrace

scarps

on

both

sides

of

the

valley.

Channel

deposits

are

exposed

in

the

Galen

gravel

pit

(sec.

36,

T.

6

N.,

E.

11

W.)

(fig.

6), the

Dempsey

Creek

gravel

pit

(sec.

20,

T.

7

N.,

E.

9

W.)

and

the

Powell

County

gravel

pit

(sec.

18,

T.

6

N.,

E.

9

W.).

The

colluvium

and

fan

deposits

are

of

variable

lithology

in

accord-

ance

to

the

source

rocks

and

travel

distances

to

the

sites

of

deposition.

The

flood-plain

deposits

are

buff

colored

owing

to

chemical

weathering

of

included

iron-bearing

rock

and

mineral

fragments.

The

flood-plain

deposits

are

mostly

silt

sized

as

shown

in

the

following

geologic

section,

but

include

local

accumulations

of

pebbles,

fine

sand,

and

clay.

VERTICAL

SCALE

EXAGGERATED

FIGURE

5. Diagrammatic

section

across

east

side

of

Deer

Lodge

Valley

showing

environmental

types

of

Pliocene

sediments

and

their

east-west

distribution.

18

GROUND-WATER

RESOURCES,

DEER

LODGE

VALLEY,

MONT.

FIGURE

6. Pliocene

channel

deposits

at

the

Galen

gravel

pit,

sec.

36,

T.

6

N.,

R.

11

W.

GEOLOGY

19

Section

of

Pliocene

flood-plain

strata

measured

across

the

high

terrace

scarp,

4

1

A

miles

northeast

of

Galen

in

NE}i

sec.

16,

T.

6

N.,

R.

9

W.

Thickness

(feet)

Silt,

buff,

finely

bedded,

semiresistant to

weathering;

contains

as

much

as

10

percent

grit,

and

pebble

lenses

1-2

in.

thick

and

3-10

ft.

long

of

sub-

angular

to

subrounded

fragments

of

granitic

and

volcanic

rocks.

_ _

_.

_

30

Silt,

buff,

fine-bedded;

contains

as

much

as

5

percent

grit__------_---_-

4

Silt,

buff,

lamellar.

_______________________________________________

4

Silt,

buff,

lamellar,

resistant

to

weathering;

contains

10

percent

volcanic

ash

____________________________________________________________

4

Silt,

buff,

lameUar__--------_________-_--____--_-----_-__-_--___--

25

Silt,

gray

to

buff,

lamellar,

resistant

to

weathering;

contains

25

percent

volcanic

ash_-._________--.__-______________--__--__-____-._-__-

2

Silt,

buff,

lamellar__---____-_________-.--_---__-__-_-___-___--__---

25

Silt,

buff,

lamellar,

resistant

to

weathering._____________^_____._____

0.

25

Silt,

buff,

lamellar

________________________________________________

6

Sand

and

grit,

light-buff,

crossbedded;

contains

a

few

percent

of

granitic

and

volcanic

pebbles

as

much

as

%

in.

in

diameter,

and

fossil

vertebrates

4

Covered.

________________________________________________________^

5

Silt,

buff,

finely

bedded;

contains

15

percent

grit,

5

percent

subangular

to

subrounded

granitic

and

volcanic

rock

pebbles

as

much

as

1J£

in.

in

diameter

______________________________________________________

6

115.

25

Lenses

of

finely

bedded

volcanic

ash

are

sometimes

intercalated

between

beds

of

the

flood-plain

silt.

In

most

instances,

for

example,

near

the

head

of

a

dry

gulch

in

the

SEi/4

sec.

29,

T.

5

N.,

E.

9

W.,

ash

overlies

a

few

inches

of

lamellar

clay

which,

in

turn,

overlies

a

few

feet

of

well-rounded,

coarse

channel

gravel

and

boulders.

These

relation-

ships

indicate

a

transition

from stream

channel

to

lacustrine,

apparently

cutoff

oxbow,

environments

of

deposition.

The

channel

deposits

are

well-rounded

detritus

from

the

marginal

highlands.

In

some

beds

the

material

has

an

average

grain

size

of

more

than

4

inches

and

includes

boulders

greater

than

1

foot

in

diameter.

The

deposits

are

typically

crossbedded,

well

sorted,

and

unconsolidated,

but

some,

notably

in

sees.

20,

21,

29,

and

32,

T.

7

N.,

E.

9

W.,

are

cemented

by

a

manganese

precipitate

or

by

lime.

A

small

patch

of

lime-cemented

paludal

and

lacustrine

silt

is

exposed

west

of Deer

Lodge

in

the

NW%

sec.

32,

T.

8

N.,

E.

9

W.

It

interfingers

laterally

with

flood-plain

silt

and

overlies

channel gravel.

More

than

100

feet

is

exposed

from the

middle of

which

was

collected

a

single

upper

molar

of

Neohipparion

sp.

(Pliocene),

USNM

22878.

A

2-foot

lens

of

dense

lacustrine

lime

is

exposed

in

gullies

tributary

to

Johnson's

Gulch

in

sec.

3,

T.

5

N.,

E.

9

W.

Fresh-water

lime

(probably

of

pre-

Pliocene

age)

was

penetrated

in

the

Montana

Power

Co.

test

hole

(State

1-1-22)

at

about

1,200

feet.

20

GROUND-WATER

RESOURCES,

DEER

LODGE

VALLEY,

MONT.

A

pair

of

fragmented

lower

jaws

of

Prosthennops

crassigenis

(Pliocene),

USNM

22877,

was

collected

during

the

course

of

this

study

from

flood-plain

silt

in

the

SW%

sec.

28,

T.

6

N.,

R.

10

W.

(Specific

identification

by

C.

Lewis

Gazin,

U.S.

Natl.

Mus.)

Konizeski

(1957,

p.

142-144)

described

111

specimens

of

13

species

of

Pliocene

mammals

collected

mostly

from

channel,

flood-plain,

and

fan

deposits.

QUATERNARY

MORAINE

DEPOSITS

The

glacial

deposits

of

the

Flint

Creek

Range

have

been

described

by

Calkins

and

Emmons

(1915),

Pardee

(1951),

Alden

(1953),

Mutch

(1960),

and

Csejetey

(1962).

The

oldest

recognizable

Quaternary

deposits

(older

moraine

de-

posits,

pi.

1)

in

the

Deer

Lodge

Valley

are

a

few

low

mounds

of

glacial

debris,

great

outwash

fans,

boulder

trains,

and

occasional

large

erratics

scattered

about

the

high

terraces.

Low

mounds

of

this

material

occur

on

the high

terrace

about

1

mile

east

of

the mountain

front

in

sees.

21

and

22,

T.

8

N.,

R.

10

W.

These

unstratified

mixtures

of

deeply

weathered

boulders

and

gravel

are

apparently

relics

of

morainal

topog-

raphy.

Extending

eastward

from

them

over

the

high

terrace

in

the

vicinity

of

Marsh

Creek

are

geat

glaciofluvial

fans,

and

boulder

and

gravel

trains.

These

deposits

range

in

thickness

from

about

30

feet

near

the

head

of

Marsh

Creek

to about

10

feet

at

the

end

of

the

terrace.

A

recent

erosion

surface

cuts

the

glacial

deposits

at

the

base

of

the

mountain

front

and

its

west

margin

is

a

fault

scarp

exposing

the

base-

ment

rocks,

which

are capped

by

older

moraine

(fig.

7).

A

large,

deeply

weathered

granitic

erratic,

known

locally

as

Sheep

Rock, lies

about

1

mile

east

of

the

mountain

front

in

sec.

21,

T.

8

N.,

R.

10

W.

It

WEST

EAST

^Flint

Creek

Range

Older

moraine

deposits

\

X\Fault-line(?)

scarp

\

f--^

Recent

erosion

surface

Basement

rocks

I

K- ^

-

I

Tertiary

deposits

VERTICAL

SCALE

EXAGGERATED

FIGURE

7. Diagrammatic

section

showing

topographic,

age,

and

structural

re-

lationships

of

older moraine,

high

terrace,

recent

erosion

surface,

and

fault-

line

(?)

scarp

south

of

Rock

Creek.

GEOLOGY

21

is

now

split

into

three

segments

but

was

originally

about

20

feet

in

diameter.

Pardee

(1951,

p.

61)

described

the

older

moraine

as

early

Pleistocene.

Alden

(1953,

p.

66)

proposed

a

pre-Wisconsin,

possibly

early

Pleisto-

cene

age.

Mutch

(1960)

reviewed

the

age

relationships

of

the

drift

in

considerable

detail.

He

concluded

that

it

is

of

two

ages:

an early

(pre-

Wisconsin)

drift

similar

to

that

mapped

as

Buffalo

Glaciation

in

other

parts

of

the

Rocky

Mountains,

and

an

intermediate (early

Wisconsin)

drift

similar

to

that

mapped

as

Bull

Lake(

?)

by

Poulter

(1957)

in the

Anaconda

Range

about

20

miles

to

the

southwest.

The

older

moraine

deposits

have

a

more

advanced

stage

of

weather-

ing

and

a

more

subdued

topography

than

the

Wisconsin

drift

in

the

area.

This

indicates

that

a

considerable

amount

of

time

and

erosion

separated the

two.

Until

more

positive

evidence

is

produced,

the

older

moraine

is

perhaps

best

considered

simply

as

of

pre-Wisconsin

age.

Terminal

moraines

of

Wisconsin

age

extend

onto

the

low

terraces

o

from

the

canyons

of

Rock

Creek,

Tincup

Joe

Creek,

Dempsey

Creek,

and

Racetrack

Creek

(pi.

1).

The

Racetrack

moraine

is

typical.

The

Racetrack

glacier,

which

was

about

14

miles

long,

flowed

eastward

down

a

great

gorge

and

terminated

in

a

broad

loop

at

the

base

of

the

mountains.

It

deposited

lateral

moraines

along

the

lower reaches

of

the

gorge

and

a

terminal

moraine

at

the

mouth.

The

lateral

moraines

are

about

1_y

z

miles

long

and

200

feet

high.

The

terminal

moraine

extends about

1

mile

downvalley

from

the

lateral

moraines

in

a

broad

loop

that

is

about

1^

miles

across,

100

feet

high,

and

5,200

feet

above

sea

level.

It

is

composed

mostly

of

unweathered

granitic

boulders,

some

of

which

are

more

than

20

feet

in

diameter.

Glaciofluvial

fans

and

gravel

trains

extend

eastward

down

the

broad

Racetrack-Dempsey

Creek

alluvial

flat.

No

terminal

moraines

occur

at

the

mouths

of

Lost

Creek,

Warm

Springs

Creek,

and

Mill

Creek,

although

(1)

those

drainages

were

occupied

by

the

greatest

ice

sheets

in

the

area,

(2)

their

mouths

lie

at

about

5,200

feet

above

sea

level,

about

the

same

altitude

as

the

terminal

lobe

of

the

Racetrack

moraine, and

(3)

recessional

moraines

occur

in

those

drainages

in

areas

upstream (and

outside)

the

study

area

(Cal-

kins

and

Emmons,

1915,

p.

11).

The

huge

coalescent

fans

of

these

three

streams

may

be

formed

of

reworked

glacial

debris

derived

from

Wisconsin

terminal

moraines.

This

would

explain

(1)

the

great

fans,

unique

in

their

size

and

location

in

the

southwestern

areas

of

the

valley,

(2)

the

very

poor

sorting

of

the

fan

material

near

the

mouths

of

the

canyons,

and

(3)

the

absence

of

Wisconsin

moraines

in

those

areas.

22

GROUND-WATER

RESOURCES,

DEER

LODGE

VALLEY,

MONT.

QUATERNARY

ALLUVIUM

Almost

three-fifths

of

the

Deer

Lodge

Valley,

or

180

square

miles,

is

mantled

by

Quaternary

alluvium.

The

material

is

chiefly

flood-plain

and

fan

deposits.

It

has

a

maximum

thickness

of

about

100

feet

at

the

heads

of

the

Warm

Springs

Creek,

Lost

Creek,

and

Mill

Creek

fans

but

has

an

average

thickness

of

about

20

feet

on

the

Clark

Fork

flood

plain.

It

generally

overlies

Pliocene

flood-plain

silt

and

clay

near

the

edge

of

the

valley

and

Pliocene

interbedded

channel

sand

and

gravel

in

the

central

areas.

In

a

few

restricted

localities,

for

example,

the

Willow

Creek

flat,

the

Quaternary

alluvium

has

an

average

depth

of

less

than

10

feet

and

lies

on

volcanic

basement

rocks.

The

Cotton

wood

Creek-Fred

Burr

Creek

fan

has

an

average

thickness

of

about

10

feet

and

overlies

Pliocene

silt.

Along

the

southeastern

margins

of

the

valley,

the

alluvium

consists

of

a

few

feet

of

slope

wash

derived locally

from

underlying

granitic

basement

rocks

of

the

Boulder

batholith.

The

flood-plain

alluvium

is

composed

of

mixtures

and interbedded

lenses

of

gravel,

sand,

silt,

lignitic

clay,

and

caliche

capped

by

carbo-

naceous

soil.

These

materials

were

derived

primarily

from

the

marginal

fans

and

secondarily

by

reworking

of

the

underlying

and

(or)

border-

ing

Tertiary

sediments.

The

fan

deposits

are

of

extremely

variable

composition

in

accordance

with

their

source,

location,

and

travel

distance

from

source

to

site

of

deposition.

The

coalescent

Lost

Creek,

Warm

Springs

Creek,

and

Mill

Creek

fans

consist

mostly

of

interbedded

lenses

of

fine

gravel,

sand,

silt,

clay,

and

carbonaceous

soil

at

the

edge,

but

the

grain

size

rapidly

coarsens

to

predominant

boulders

and

coarse

gravel

near

the

mouths

of

the

three

canyons.

Variation

of

the

lithology

of

the

fan

deposits

is

exemplified

by

the

material

in

the

Tri-City

gravel

pit

near

the

head

of

the

Mill

Creek

fan

in

sec.

8,

T.

4

N.,

E.

10

W.,

as

contrasted

with

the

material

in

the

Pioneer

gravel

pit

near

the

head

of

the

Clark

Fork

fan

in

sec.

36,4

N.,

E.

10

W.

(table

1).

The

glaciofluvial

fans

below

the

Wisconsin

moraines

are

composed

of

mixtures

and

lenses

of

sand,

gravel,

and

boulders.

Grain

size

generally

diminishes

from

boulders

and

coarse

gravel

near

the

moraines to

fine

gravel

and

sand

at

the

outer

margins

of

the

fans.

The

Cottonwood

Creek-Fred

Burr

Creek

fan

contains

no

glacial

debris

and

consists

mostly

of

silt,

sand,

and

gravel

capped

by

a

few

feet

of

sandy

soil.

Two

unique

Quaternary

deposits

occur

on

high

terrace

remnants

near

the

mouth

of Warm

Springs

Canyon.

The

first

is

north

of

the

canyon

where

about.

3

square

miles

of

uneven

erosional

surfaces

are

formed

on

welded

tuff

and

Tertiary

beds.

Scattered

about

the

topographic

highs

and

sometimes

forming

thin

sheets

of

material

about

one

boulder thick

are

well-rounded,

water-worn

boulders

of

Belt

GEOLOGY

23

TABLE

1.

Report

on

samples

of

gravel

from

Deer

Lodge

Valley,

Moni.

[Submitted

by

U.S.

Dept.

of

Commerce,

Bur.

of

Public

Koads,

Washington,

D.C.,

1955.

Values

are

in

percent

of

size

fraction]

Fine-

Size

fraction

grained

Miscel-

Source

Lab.

No.

(inches)

Quartzite

Granite

volcanics,

Gneiss

laneous

mostly

dacite

Tri-City

pit

NE*4 sec.

8,

T.

4

12

75

..--__________

13

Pioneer

pit

NEJ4

SWK

sec.

36,

T.

4

N.,

R.

10

W______

1M>-1

\-%

%-y*

Vz~%

As

received

92954

__

2-1

H

i-Y

%-tt

As

2

received

22

18

21

20

94

80

78

74

58

78

64

70

65

70

66

1

2

5

1

4

3

6

4

14

17

24

34

17

7

5

3

4

6

3

4

5

1

4

6

5

3

2

3

4

quartzite.

These

boulders

average

about

8

inches

in

diameter,

but

some

are

more

than

3

feet.

Their

source

is

about

20

miles

to

the

west

up

Warm

Springs

Creek.

Their

occurrence

here

may

be

explained

in

three

ways.

1.

It

has

been

suggested

(F.

A.

Swenson,

oral

commun.,

1961)

that

the

boulders

were

transported

to

and

emplaced

in

their

present

locale

by

early-day

mill

workers

to

prevent

erosion

of

the

old

smelter

foundations.

Lending

credence

to

this

hypothesis

is

the

fact

that

in

one

area

the

boulder

fields

stop

abruptly

at

the

boundary

be-

tween

relatively

easily

erodable

sediments,

which

are the

plant

beds

of

Csejetey

(1962),

and

the

welded

tuff.

However,

it

is

diffi-

cult

to

visualize

early-day

horse-powered

transportation

of

boul-

ders

2

or

3

feet

in

diameter

for

distances

of

20

or

more

miles.

Fur-

thermore,

the

material

occurs

in

lesser

amounts

in

many

areas

where

there

is

no

evidence

of

early

mill

workings.

2.

It

may

be

that

the

boulder

fields

are

erosional

lag

deposits.

In

large

areas

much

well-rounded

Belt

debris

is

incorporated

within

the

underlying

Tertiary

deposits.

However,

its

distribution

in

the

Tertiary

deposits

does

not

seem

to

satisfy

the

requirements

for

its

distribution

in

the

boulder

field.

3.

Perhaps

the

most

probable

explanation

is

that

the

Belt

debris

had

a

glacial

origin

comparable

with

that

of

the

older

moraine in

the

24

GROUND-WATER

RESOURCES,

DEER

LODGE

VALLEY,

MONT.

Marsh

Creek

area

and

was

originally

deposited

on

the high

ter-

races

about

the

mouth

of Warm

Springs

Canyon.

Interglacial

erosion

removed

most

of

the

other

material

and

left

the

topo-

graphic

highs

capped

by

boulders.

The

second

unique

deposit

is

on

the

high

terrace

remnants

south

of

the

mouth

of

Warm

Springs

Creek

canyon.

A

great

bed

of

travertine

slopes

gently valleyward

and

covers

about

1

square

mile.

Outlying

patches

extend

westward

about

2

miles

above

the

mouth

of

the

canyon.

The

travertine

averages

less

than

10

feet

in

thickness

but

ranges

up

to

20

feet

and

overlies

about

10

feet

of

poorly

cemented

boulder

con-

glomerate.

Numerous

impressions

of

plant

stems

are

encrusted

in

the

travertine,

which

was

formed

by

springs

along

the

base

of

the

mount-

tains.

The

Anaconda

Hot

Springs

still

flow

and

lime

is

being

added

to

the

extensive

travertine

deposits.

Silt

and

sludge

from

the

settling

basins

of

the

Washoe

Smelter

(pi.

1)

cover

about

10

square

miles

of

the

Mill

Creek,

Warm Springs

Creek,

and Lost

Creek

alluvial

fans.

This

material

has

an average

thickness

of

about

20

feet

and

a

maximum

thickness

of

about

75

feet.

REGIONAL

STRUCTURE

Most

of

the

sedimentary

basement

rocks

in

the

mountains around

the

Deer

Lodge

Valley

have

been

folded

and

faulted. Along

the

front

of

the

Flint

Creek

Range

they

are

generally

folded

into

a

series

of

anticlines

and

synclines

that

trend

northeast-southwest.

The

Eange

has

been

described

by

Pardee

(1951,

p.

402)

as

a

domal

structure

that

was

probably

formed

by

folding

rather

than

faulting.

Mutch

(1960)

agrees

with Pardee

that

the

northern

part

of

the

Flint

Creek

Range

appears

to

be

arched

but

describes

the

Mount

Powell

fault

as

evidence

to

show

that

the

change

from

broad

gentle

slopes

around

the

margins

of

the

northern

part

of

the

range

to

abrupt

valley-wall

relief

south

of

Rock

Creek

is

probably

due

to

recent

faulting.

The

remarkably

straight

erosion

scarp

between

Rock

Creek

and

Robinson

Creek

cuts

uniformly

across

basement

rocks

and

unconsolidated

drift

along

its

21/2-mile

extent

(pi.

1,

fig.

7)

and

may

be

a

recent

faultline

scarp.

INTRAVALLEY

STRUCTURE

As

indicated

by

gravity

data

(p.

29),

the

minimum

altitude

of

the

basement

rocks

is

east

of

Anaconda

and

is

about

700

feet

below

sea

level.

A

water

well

drilled

by

the

Northern

Pacific

Railroad

Co.

in

Cenozoic

fill

at

Garrison

bottomed

in

basement

rocks

at

about

4,334

feet

above

sea

level;

therefore

the

valley

is

a

closed

structural

basin.

Most

of

the

exposed

lower

or

middle

Tertiary

beds

and

the

associ-

ated

welded

tuff

unit

of

the

Lowland

Creek

Volcanics

have

been

GEOLOGY

25

greatly

deformed

by

folding,

faulting,

or

slumping.

Some

are

com-

pletely

overturned.

Near

the

mouth

of

Warm

Springs

Canyon

they

are

variously

oriented;

but

between

Spring

Gulch

and

Dempsey

Creek,

there

is

generally

a

westward

trend

in

dip

(pi.

1).

Much

of

the

Miocene

fill

is

also

deformed.

Across

the

north

end

of

the

valley,

in

the

area

between

Marsh

Creek

and

Rock

Creek,

the

dip

trends

south-southeast

(pi.

1).

The

few

patches

of

exposed

Miocene

sediments

on

the

east

side

of

the

valley

are

undef

ormed.

The dip

of

the

exposed

Pliocene

strata

is

about

parallel

to

the

slope

of

the

high

terrace

and

is

probably

a

function

of

the

original

environ-

ment

of

deposition.

However,

some

of

the

Pliocene

strata

between

Modesty

Creek

and

Spring

Gulch

are

down

faulted

to

the

west

and

dip

into

the

Flint

Creek

Range

(pi.

1).

The

down

faulting

and

the

westward

dip

of

the

lower

or

middle

Tertiary

strata

are

probably

due

to

local

subsidence

along

the

base

of

the

Flint

Creek

Range.

Seismic

data,

recorded

by

the

Montana

Power

Co.,

indicate

that

the

Mount

Powell

and

associated

faults

extend

into

the

valley

and

cut

at

least

the

oldest

Tertiary

strata.

The

seismic

data

also

indicate

about

300

feet

of

vertical

displacement

along

the

main

(normal)

fault

near

the

mountain

front,

but

only

about

200

feet

at

a

distance

of

3

miles

into

the

valley.

Only

about

100

feet

of

displacement

was

recorded

along

the

southern

(thrust)

fault.

As

there

are

no

good

exposures

along

the

faults,

it

cannot

be

determined

if

the

Pliocene

strata

have

been

cut.

Because

there

are

no

surface

expressions

of

the

faults

within the

valley,

most

movement

must

have

been

before

the

high

terraces

were

formed,

although

recent

movement

is

indicated

at

the

base

of

the

mountain

front.

The

Miocene

lacustrine

deposits

plastered

onto

the

lower

mountain

slopes

above

intravalley

Pliocene

fill

might

be

ascribed

to

post-

Miocene,

pre-Pliocene

erosional

sequence,

but

their

position

is

more

logically

explained

by

faulting.

The

northward

lateral

migration

of

cross-terrace

ravines

(Konizeski,

1957,

p.

138)

indicates

that

moderate

uplift

in

the

marginal

eastern

areas

of

the

valley

occurred

after

the

deposition

of

the

older

drift.

TERTIARY

HISTORY

According

to

Weeks

and

Klepper

(1954,

p.

1320-1321),

major

fold-

ing

and

local

thrust

faulting

in

the

northern

Boulder

batholith

region

east

of

the

Deer

Lodge Valley

culminated

in

the

very

Late

Cretaceous

or

very early

Tertiary

emplacement

of

the

batholith.

"Uplift

and

ero-

sion

during

Paleocene

and

Eocene

time

resulted

in

a

mountainous

terrane

and

partial

deroofing

of

the

batholith.

Oligocene

gravel

and

rhyolitic

sediments

accumulated

in

subsiding

intermontane

basins;

293-420

O 68-

26

GROUND-WATER

RESOURCES,

DEER

LODGE

VALLEY,

MONT.

tilting

of

Oligocene

basin

deposits,

partly

associated

with

movement

on

the range

front

faults,

preceded

deposition

of

stream

gravels

of

Miocene

and

Pliocene

age.

Pediments

formed

in

late

Tertiary

to

Pleistocene

(?)

time."

Ruppel,

in

a

summary

of

the

evolution

of

landforms

in

the

Basin

quadrangle

(1957,

p.

94,

1963,

p.

83),

suggests a

mature

mountainous

Oligocene

erosion

surface

of

perhaps

3,000

feet

of

maximum

relief

and

a

broad,

deeply

weathered

late

Miocene(?)

surface

that

was

nearly

flat

but

above

which

a

few

rounded

mountains

rose

perhaps

500-1,000

feet.

He

postulates

further

that

this

surface

was

then

up-

lifted

and

that

Pliocene

and

Pleistocene

erosion

carved

a

landscape

similar

to

that

of

today.

Smedes

(1962,

p.

259)

depicts

deposits

of

the

basal

unit

of

the

Low-

land

Creek

Volcanics

as

accumulating

on

the

Oligocene

erosion

surface

described

by

Ruppel.

If

the

radiometric

date of

Baadsgaard

is

valid,

this

surface

would

be

early

Eocene

or

older,

and

erosion

of

the

coun-

try

rocks

and

breaching

of

the

batholith

progressed

at

a

much

faster

rate

than

has

formerly

been

supposed.

The

Deer

Lodge Valley

probably

was

a

major

topographic

low

during

deposition

of

the

Lowland

Creek

Volcanics

(early

Eocene).

The

volcanics

filled

various

canyons

about

the

base

of

the

Flint

Creek

Range

and

the

abrupt

relief

and

orientation

of

these

canyons

suggests

a

major topographic

low

to

the

east.

The

volcanics

crop

out

on

the

east,

west,

and

south

sides

of

the

valley

(Smedes,

1962,

fig.

1)

and

probably

accumulated

in

the

valley

as

indicated

by

a

test

well

(State

1-1-22),

which

bottoms

in

tuff(?)

at

2,536

feet.

Because

this

well

generally

penetrated

fine-grained

sedimentary

deposits

and

some

limestone

beds,

the

topographic

relief

in

the

valley

was

probably

relatively

low

during

the

early

to

middle

Tertiary.

During

Miocene

time

the

ancestral

Clark

Fork

may

have

flowed

southward

as

postulated

by

Perry

(1934,

p.

6-7).

In

late

Miocene

or

early

Pliocene

the

north

end

of

the

Deer

Lodge

Valley

was

down

faulted

at

least

several

hundred

feet

and

the

Tertiary

deposits

were

faulted

and

tilted.

In

Pliocene

time

the

lithology

of

the

accumulating

valley

fill

indicates

regional

topographic

relief

comparable

to

that

now

in

exist-

ence

(Konizeski,

1957,

p.

147).

Coarse

gravel

and

sand

were

deposited

along

the

channel

of

the ancestral

Clark

Fork

in

the

center

of

the

valley;

silt

and

minor

amounts

of

fresh water

lime

were

deposited

in

the

bordering

flood

plain;

and

colluvium

and

slope

wash

were

depos-

ited

along

the

margins

of

the

valley.

Intermittent

falls

of

volcanic

ash

were

incorporated

in

the

accumulating

erosion

detritus.

Some

of

GRAVIMETRIC

SURVEY

27

the

Pliocene

and

older

deposits

were

faulted

and

tilted

in the late

Pliocene.

QUATERNARY

HISTORY

The

high

terraces

are

remnants

of

a

valleywide,

erosional

surface

formed

during

either

late

Pliocene

or

early

Pleistocene

before

deposi-

tion

of

the

older

moraine.

This

is

evidenced

by

local

beveling

of

middle

Pliocene

strata

and

by

the

capping

outwash

trains

from

the

older

moraine.

After

deposition

of

the

older moraine

but

before

Wisconsin

time,

the

Clark

Fork

and

its

tributaries

entrenched

themselves

about

150

feet

into

the

Tertiary

strata

and

into

the

basement

rocks

at

the

outlet

of

the

valley.

The

entrenchment

was

during

erosional

cycles

that

perhaps

were

glacial-interglacial

periods

and

(or)

inter-

mittent

tectonic

activity

north

of

the

study

area.

The

low

terraces

were

cut

during

the

last

cycle;

the

surface beneath

the

Clark

Fork

flood-plain

alluvium

was

cut

during

the

post-Wisconsin

cycle.

Between

Mill

Creek

and

Kacetrack

Creek

the

high

terraces

have

been

mostly

beveled

to

an

intermediate

level,

but

some

remnants

still

remain

along

the

mountain

front.

Great

Wisconsin moraines

were

subsequently

deposited

on

the

low

terraces

at

the

mouths

of

the

principal

tributary

canyons

north

from

Kacetrack

Creek

and

perhaps

at

the

mouths

of

Mill,

Lost,

and

Warm

Springs

Creeks.

Large

boulder

trains

have

also

been

deposited

on

the

low

terraces

below

the

still

fresh

Kacetrack,

Dempsey,

Tincup

Joe,

and

Rock

Creeks

Wisconsin

moraines.

About

20

feet

of

Recent

alluvium,

derived

from

a

variety

of

sources

around the margins

of

the

valley,

has

accumulated

on

the

Clark

Fork

flood

plain.

Uplift,

which

occurred

after

deposition

of

the

older

moraine

and

as

late

as

Recent

time,

affected

the

southeastern

areas

of

the

valley.

The

uplift

was

accompanied

and

followed

by

northward

migration

of

tribu-

tary

streams

on

the

east

side

of

the

valley.

The

recently

formed

scarp

trending

north-south

at

the

base

of

the

mountain

slopes

between

Robinson

Creek

and Mullan

Creek

may

be

a

faultline

feature.

GRAVIMETRIC

SURVEY

By

E.

A.

CBEMEE

III

A

gravity

survey

was

made

in

the

southern

part

of

the

Deer

Lodge

Valley,

Mont.,

in

1960

to

determine

approximate

depths

of

valley

fill

and,

if

possible,

to

interpret

subsurface

features

and

bedrock

configu-

ration.

The

investigation

was

made

under

the

auspices

of

the Uni-

versity

of

Montana,

and

the

work

was

supervised

by

faculty

members

R.

M.

Weidman

and

John

Hower.

The

gravity

meter

was

rented

by

the

U.S.

Geological

Survey

and

the

University

of

Montana.

28

GROUND-WATER

RESOURCES,

DEER

LODGE

VALLEY,

MONT.

METHODS

Gravity

readings

were

made

at

more

than

300

stations

(pi.

2)

with

a

portable,

temperature-compensated

World-Wide

gravity

meter.

The

uncorrected

readings

are

believed

to

be

accurate

to

the

nearest

0.05

mgal

(milligal)

relative

to

each

other.

The

observed

gravity

values

and

corrections

are

available

at

the

U.S.

Geological

Survey

office

in

Helena,

Mont.

About

one-half

of

the

stations

were

on

three

traverses

across

the

valley

and

three

short

trunklines

in

the

southwest

part

of

the

area.

Stations

on

the

cross-valley

traverses

were

about

one-fourth

mile

apart;

those

on

the

short

lines

were

about

one-eighth

mile

apart.

The

other

one-half

of

the

stations

were

randomly

scattered

throughout

the

area

where

altitude

data

were

available.

Altitudes

at

the

stations

were

determined

by

instrumental

leveling

and

are

generally

accurate

to

the

nearest

foot.

To

determine

the instrumental

drift,

an

additional

reading

was

made

at

a

station

where

a

reading

was

taken

one

or

two

hours

before.

REDUCTION

OF

DATA

The

observed

gravity

values

were

corrected

for

drift,

then

the

standard

free-air,

Bouguer,

and

latitude

corrections

were

made

as

described by

Nettleton

(1960,

p.

41-58).

An

assumed

density

of

2.5

was

used

for

the

Bouguer

correction.

Terrain

corrections

using

tables

published

by

Hammer

(1939)

were

made

for

28

selected

stations

throughout

the

area

and

interpolated

values

were

applied

to

all

other

stations.

By

comparing

gravity

values

of

stations

on

basement

rock,

a

re-

gional

gravitational

gradient

was

found

to

be

representable

as

a

flat

surface

sloping

to

the

southwest.

This

surface

was

mapped

and

super-

imposed

on

the

overall

gravity

map.

The

appropriate

value

was

then

subtracted

from

each

station

thus

leaving

a

residual

gravity

map

showing

the

anomaly

caused

by

varying

depths

of

fill

(pi.

2).

The

maximum

regional

correction

for

the

entire

area

was

29.9

mgal;

how-

ever,

the

maximum

correction

for

the

area

covered

by

the

residual

gravity

map

was

only

13.7

mgal.

This

correction

limits

the

precision

of

the

final

values

but

is

probably

sufficiently

accurate

to

justify

the

2-mgal

interval.

RESULTS

Without

other

information,

there

is

no

unique

interpretation

of

gravity

data.

In

this

gravimetric

survey,

surface

and

subsurface

geology

aided

the

interpretation

of

the

gravity

data.

The

residual

gravity

map

(pi.

2)

shows

a

rapid

decrease

in

gravity

along

the

sides

and

southern

end

of

the

valley.

The

values

in

the

central

part

of

the

valley

are

comparatively

constant.

A

gravity

low

in

the

southern

part

of

the

area

has

about

20

mgal

of

residual

gravity

GRAVIMETRIC

SURVEY

29

relief

relative

to

bedrock

areas.

The

low

basement

rock

values

in the

western

part

of

T.

5

N.

could

be

caused

by

low-density

volcanic

tuffs

(K.

L.

Konizeski,

written

common.,

1960).

Three

east-west

sections

(pi.

2)

were

calculated

by

using

a

grati-

cule

as

described by

Nettleton

(1940,

p.

115)

to

convert

corrected

gravity

readings

to

depth

to

basement

rock.

An

assumed

density

con-

trast

of

0.6

gram

per

cubic

centimeter

between

the

valley

fill

and

basement

rocks

was

used.

The

sections

were

prepared

to

determine

the

approximate

thickness

of

valley

fill

and

to

help

interpret

struc-

tural

relationships.

The outstanding

feature

of

the

three

sections

(pi.

2)

is

a

sudden,

large

break

in

slope

at

the

eastern

end

of

each.

This

almost

certainly

represents

a

major

fault

along

the

foot

of

the

mountains

on

the

east

side

of

the

valley.

This

fault

is

probably

a

continuation of

a

known

fault

southeast

of

the

valley

(R.

L.

Konizeski,

written

commun.,

1960).

There

is

also

definite

indication

of

a

smaller

fault

at

the

west-

ern

end

of

section

A-A'

and,

to

a

lesser

degree,

of

section

B-B'.

The

magnitude

of

the

break,

the

sharpness

of

the

subsurface

features,

and

the

depth

of

valley

probably

preclude

the

possibility

of

the

anomaly

being

caused

by

a

terrace.

Section

C-C'

did

not

extend

far

enough

west

to

cross

a

northern

projection

of

the

known

Mount

Powell

fault

that

extends

into the

valley

between

sections

B-B'

and

C-C'

and

bends

northward

along

the

foot

of

the

Flint

Creek

Range.

Because

the

valley

fill

is

thicker

at

the

western

end

of

the

section,

which

is

near

the

mountains,

than

it

is

towards

the

center

of

the

valley,

the

Mount

Powell

fault

probably

extends

at

least

as

far

north

as

section

C-C'.

The

above

geophysical

evidence

indicates

the

valley

was

formed

by

faulting.

An

ambiguous

feature

shown

by

the

three

sections

is

the

bedrock

high

in

the

middle

of

the

valley.

This

may

be

attributed

to

faulting

of

the

valley

floor

or

erosion

but

is

more

likely

caused

by

lava

flows

down

the center

of

the

valley.

A

flow

of

lava

or

a

series

of

interbedded

flows

of

less

thickness

than

the

indicated

bedrock

high,

but

closer

to

the

land

surface,

could

result

in

a

calculated

valley

floor

similar

to

that

shown.

Andesite

flows

at

the

north

and south

ends

of

the

valley

give

credence

to

the

explanation.

The

tight

lines

in

the vicinity

of

sec.

21,

T.

4

N.,

R.

10

W.

(pi.

2)

are

caused

by

an

andesite

flow.

The

decreasing

thickness

of

the

valley

fill

from

more

than

5,500

feet

in

the

south

to

about

2,300

feet

near

Deer

Lodge

indicates

that

at

one

time

drainage

from

the

area

may

have

been

to

the

south

as

postulated

by

Perry

(1934,

p.

6-7).

30

GROUND-WATER

RESOURCES,

DEER

LODGE

VALLEY,

MONT.

SUMMARY

There

is

a

large

fault

along

the

eastern

side

of

the

Deer

Lodge

Valley

and

probably

a

smaller

one

along

the

western

side.

These

faults

indicate

a

tectonic

origin

of

the

Deer

Lodge

Valley.

The

maximum

depth

of

fill

is

more

than

5,500

feet

east

of

Anaconda.

The

depth

of

fill

decreases

to the

north.

GROUND

WATER

Scientific

studies

have

shown

that

(1)

practically

all

ground

water

is

derived

from

precipitation,

(2)

most usable

ground water

is

an

im-

portant

component

of

the

hydrologic

cycle,

(3)

ground water

obeys

natural

laws,

and

(4)

the

occurrence

of

ground

water

is

intimately

as-

sociated

with

the

geology

of

the

area.

DEFINITION

OP

SELECTED

HYDROLOGIC

TERMS

The

following

definitions

are

based

largely

on

those

given

by

Meinzer

(1923b).

A

few

terms

not

included

in

the

following

list

are

defined

where

they

are

introduced

in

the

text.

Aquifer,

a

formation,

group

of

formations,

or

part

of

a

formation

that

will

yield

ground

water

in

useful

quantities.

Artesian

aquifer,

a

confined

aquifer

in

which

ground

water

rises in

a

well

above

the

point

at

which

it

is

found

in

the

aquifer.

Confining

bed,

a

bed

which

overlies

an

aquifer and

which,

because

of

its

low

permeability

relative

to

the

aquifer,

prevents

or

impedes

upward

loss

of

water

and

pressure;

a

similar

bed

beneath

an

aquifer

that

prevents

or

impedes

downward

loss

of

water

and

pressure.

Drawdown,

lowering

of

the

water

level

in

a

well

as

the

result

of

pumping.

Effluent

flow,

flow

of

water

from

the

ground-water

reservoir

to

surface

water.

Evapotranspiration,

the

combined

discharge

of

water

to

the

air

by

direct

evapora-

tion

and

plant

transpiration.

Flowing

well,

an

artesian

well

through

which

water

is

forced

above

the

land

surface

by

pressure

in

the

aquifer.

Influent

flow,

flow

of

water

into

the

ground-water

reservoir

from

surface

water.

Permeability,

a

measure

of

the

capacity

of

an aquifer

to

transmit

water.

Permeability,

field coefficient

of,

the

rate

of

flow

of

water,

in

gallons

per

day

under

prevailing

conditions,

through

a

cross

section

of

aquifer

1

foot

high

and

1

mile

wide,

under

a

hydraulic

gradient

of

1

foot

per

mile.

Piezometric

surface,

an

imaginary

surface

that

everywhere

coincides

with

the

static

head

of

water

in

an

aquifer.

Porosity,

the

ratio

of

the

volume

of

the

openings

in

a

rock

to

the

total

volume

of

the

rock.

Recovery,

the

residual

drawdown

after

pumping

has

stopped.

Specific

capacity,

a

measure

of

the

productivity

of

a

well;

the

amount

of

water,

in

gallons

per

minute,

that

is

yielded

per

foot

of drawdown.

Storage,

coefficient

of,

a

measure

of

the

capacity

of

an aquifer

to

store

and

release

water;

the

volume

of

water

released

from

or

taken

into storage

per

unit

surface

area

of

the

aquifer

per

unit

change

in

the

component

of

head

normal

to

that

surface.

GROUND

WATER

31

Transmissibility,

coefficient

of,

the

rate

of

flow

of

water,

in

gallons

per

day

under

prevailing

conditions,

across

each

mile

strip

extending

the

saturated

thickness

of

the

aquifer,

under

a

hydraulic

gradient

of

1

foot

per

mile.

It

is

equal

to

the

fleld

coefficient

of

permeability

multiplied

by

the

saturated

thickness

of

the

aquifer,

in feet.

Water

table,

the surface within

the

zone

of

saturation

where

the

pressure

is

atmospheric.

Water-table

aquifer,

an

aquifer

which

is

not

confined

above.

In

this

type

of

aquifer

the

water

level

in

a

well

indicates the

water

table.

Zone

of

aeration,

the

zone

in

which

the

open

spaces

in the

rocks

are

filled

with

air

and

water.

Zone

of

saturation,

the

zone

in

which

the

open

spaces

in

the

rocks

are

com-

pletely

filled

with

water.

PRINCIPLES

OF

OCCURRENCE

In

the

Deer

Lodge

Valley

most

of

the

ground

water

occurs

in

the

pore

spaces

between

the

grains

of

the Quaternary

and

Tertiary

sedi-

ments

;

some

occurs

in

the

joints

and

fractures

of

the

indurated

volcanic

rocks.

Part

of

the

water

from

precipitation,

from

irrigation,

and

from

influent

streams

seeps

into

the

soil

and

percolates

downward

through

the

zone

of

aeration

to

the

zone

of

saturation.

In

the

zone

of

saturation

the

open

spaces,

which

are

generally

interconnected,

act

as

conduits

through,

which

ground

water

moves.

The

rate

of

movement

of

ground

water

is

measured

in

feet

per

day

or

feet

per

year,

whereas

that

of

sur-

face

water

is

measured

in

feet

per

second.

Stored

ground

water

seeps

into

stream

channels

to

maintain

streamflow

throughout

the

year.

Ground

water

is

discharged

by

springs,

wells,

and

effluent

streams,

or

by

evaporation

and

transpiration

(evapotranspiration). Under

natural

conditions

the

discharge

from

the

reservoir

was

equal

to

the

recharge.

Irrigation

of

agricultural

land

and

industrial

development

in

the

valley

changed

the

natural

conditions.

However,

the

change

was

far

enough

in

the

past

that

a

new

balance

between

recharge

and

dis-

charge

has

been

fairly

well

established.

The

geology

determines

whether

the

water

is

artesian

(confined)

or

water

table

(unconfined).

In

the

Deer

Lodge

Valley,

water

in

the

Ter-

tiary

rocks

is

generally

confined,

but

water

in

the

Quaternary

rocks

is

generally

unconfined.

The

geology

also

determines

to

a

great

extent

the

depth

to

water

in

the

underground

reservoir.

In

some

places

in

the

valley,

as

in

seeps

and

swamps,

the

water

is

at

the land

surface.

In

the

flood-plain

alluvium

of

the

Clark

Fork

and

some

of

its

tribu-

taries,

the

water

table

is

within

5

to

10

feet

of

the

land

surface.

In

some

of

the

alluvial

fans

and

under

most

of

the

terraces

the

water

table

may

be

from

10

to

more

than

150

feet

below

the

surface.

Depths

of

wells

in

the

valley

range

from

a

few

feet

to

250

feet.

32

GROUND-WATER

RESOURCES,

DEER

LODGE

VALLEY,

MONT.

HYDROLOGIC

PROPERTIES

OF

WATER-BEARING

MATERIALS

The

hydrologic

properties

of

an

aquifer

include

the ability

to

store

and

to

transmit

water,

as

measured

by

the

porosity

and

by

the

coeffi-

cients

of

storage

($),

permeability,

and

transmissibility

(T).

These

properties

control

(1)

the

ability

of

the

aquifer

to

take

water

into

storage and

release

it

from

storage and

(2)

the

movement

of

water

through

the

aquifer

from

the

area of

intake

to

the

area of

discharge.

The

coefficient

of

transmissibility

of

the

Quaternary

alluvium

and

Tertiary

sediments

was

obtained

in

several

places

in

the

Deer Lodge

Valley

by

aquifer

tests.

Pumping

water

from

a

well

develops

a

cone

of

depression

in

the

water

table

around

the

pumped

well.

The

base

of

the

cone

is

the

static

water

level

and

the

height

is

equal

to the

drawdown

in

the

well.

The

drawdown

in

the

pumped

well

depends

upon

the

pump-

ing

rate,

the

time

since

pumping

began,

the

transmissibility

and

stor-

age

properties

of

the

aquifer,

and

the

well

construction.

The

area

affected

by

pumping

(area

of

influence)

depends

upon

the pumping

rate,

the

time

since

pumping

began,

and

the

transmissibility

and

stor-

age

properties

of

the

aquifer.

The

cone

of

depression

around

a

pumped

well

increases

in

depth

and

area

until

it

intercepts

enough

rejected

re-

charge

or

reduces

natural

discharge

to

equal

the

amount

of

water

be-

ing

pumped

from

the

well.

After

pumping

is

stopped,

the

water

table

surrounding

the

well

will

eventually

return

almost

to

its

original

posi-

tion.

By

pumping

a

well

at

a

known

constant

rate

for

a

measured

time

and

by

recording

drawdown

during

pumping

and

recovery

after

pump-

ing,

enough

data

can

be

collected

to

use

in

formulas

developed

by

Theis

(1935,

p.

519-524)

and

by

Jacob

(1947,

p.

1047-1070)

for

computing

the

coefficients

of

transmissibility and

storage.

The

coefficients

of

trans-

missibility

and storage

can

be

used

with

other

data

to

(1)

estimate

yield

and

drawdown

for

proposed

wells,

(2)

determine

the

amount

of

ground

water

flowing

through

an

aquifier,

and

(3)

determine

the

rate

at

which

ground

water

is

moving.

MULTIPLE-WELL

TESTS

An

aquifer

test

using

the

pumped

well

and

one

or

more

observation

wells

is

termed

a

multiple-well

test.

The

coefficient

of

transmissibility

of

the

aquifer

at

three

sites

was

determined

from

this

type

of

test

(table

2).

At

one

test

site,

the

observation

well

was

a

domestic

well;

at

the

other

two

sites,

temporary

observation

wells

were

installed

by

driving

a

%-inch

pipe

into

the

ground.

This

type

of

test

setup

is

not

ideal

for

testing

an

aquifer

because

the

aquifer

thickness

at

the

obser-

vation

well

is

not

known

and

generally

the

test

well

only

partly

pene-

trates

the

aquifer.

However,

data

obtained

from

the

tests

are

worth-

GROUND

WATER

33

TABLE

2.

Aquifer

test

data

[Geologic

source:

A,

Quaternary

alluvium;

T,

Tertiary

sediments]

Draw-

Specific

Coefficient

Geologic

Depth

Pump-

down

in

Length capacity

of

transmis-

Well

source

of

well

ing

rate

pumped

of

test

(gpm

per

sibility

Remarks

(feet)

(gpm)

well

(minutes)

ft)

(gpd

per

(feet)

ft)

B4-10-

5ab...

15aa~-

B5-10-17dc

.

23cb.

24aa

_

.

B6-

9-

4ab._-

4bb._-

4CC~_-

7ad2_-

7dc

.

B6-lo-14bc

.

15aa

.

B7-

9-17ad.--

32da__-

B8-

9-15ab__-

15bal_-

21dal--

21da2._

27ac.._-

B9-

9-34CC-.-

A,

T

A

A(?)

A,

T

A

A,

T

A

T

A

T(?)

A

T(?)

T

160

23.

71.

150

200

18.

14.

8.

35

40

126

12.

34

19.

23.

14.

12.

11.

17.

1

3

0

6

1

6

4

5

2

4

61

11

270

580

975

28

27

10

92

110

85

30

135

22

9

55

25

52

5

3

10.

29.

38.

102.

4.

i!

3.

2.

3.

2.

7.

2.

4.

2.

2'.

1.

2.

,6

5

2

3

1

8

2

0

5

2

7

4

0

7

6

0

30

470

1,800

450

220

300

200

180

200

250

300

30

150

200

350

240

330

120

1

9

15

10

7

34

6

24

50

28

12

19

8

2

28

36

20

3

1

95,000

20,000

77,

000

20,000

15,000

80,000

40,

000

25,000

35,000

175,

000

80,

000

35,000

38,

000

60,000

800

50,

000

50,000

35,000

1,000

600

Casing

too

wet

to

measure

water

level

while

pump-

ing.

Large

entrance

loss

into

casing.

Ob-

servation

well

40

ft

away.

Large

entrance

loss.

Observation

well

550ft

away.

Screened

and

gravel

packed.

Large

entrance

loss

into

easing

.

Observation

well

50

ft

away.

while

when

used

with

the

knowledge

of

the

conditions

under

which

the

tests

were

made.

Well B6-9-7dc

fully

penetrates

the

aquifer

and

is

perforated

and

developed;

the

saturated

thickness

did

not appreci-

ably

decrease

during

the

test,

and

the

observation

well was

about

twice

the

saturated

thickness

(m)

from

the

pumped

well.

Therefore,

results

are

believed

to

be

fairly

good.

Neither

well

B4-10-15aa

nor

B5-10-

17dc

fully

penetrates

the

aquifer.

The

drawdown

in

the

observation

well

at

test

site

B4^10-15aa

was

affected by

the

partial

penetration

of

the

pumped

well,

but

no

correction

could

be

made

because

the

satu-

rated

thickness

of

the

aquifer

was

not

known.

Because

the

observation

well

at

test

site

B5-10-17dc

was

not

affected

by

partial

penetration,

no

correction

was

required.

The

maximum

drawdown

during

the

test

on

wells

B4-10-15aa

and

B5-10-17dc

was

10.6

feet

and

29.5

feet

re-

spectively

;

the

theoretical

drawdown

in

a

well

with

an

effective

radius

of

1

foot

(based

on

the

calculated

values

of

T

and

an

estimated

value

of

8

of

0.05)

was

less

than

1

foot

and

5

feet,

respectively.

Therefore,

most

of

the

measured

drawdown

in

the

pumped

wells

was

due

to

entrance

loss,

and

the

saturated

thickness

probably

did

not

decrease

sufficiently

to

necessitate

correction

of

drawdowns.

Water

from

a

stream

about

200

feet

south

of

well

B4-10-15aa

apparently

decreased

the

rate

of

draw-

down

in

the

observation

well.

34

GROUND-WATER

RESOURCE'S,

DEER

LODGE

VALLEY,

MONT.

In

the

development

of

Theis's formulas,

it

was assumed

that

the

coefficient

of

storage

is

constant

and

that

water

is

instantaneously

released

from

storage

as

the

head

declines.

In

tests

made

under

water-table

conditions

the

water

is

derived

from

storage

by

gravity

drainage,

which

is

generally

slow.

Thus,

the

coefficient

of

storage

as

calculated

from

the

aquifer

test

data

appears

to

increase

as

pumping

time

increases

and

drainage

is

more

complete.

Because

complete

drain-

age

of

the

rocks

in

the

cone

of

depression

might

require

several

weeks

or

months

of

pumping,

the

coefficient

of

storage

was

not

determined.

SINGLE-WELL

TESTS

An

aquifier

test

using

only

the

pumped

well

is

termed

a

single-well

test.

Theis

(1935,

p.

522)

stated,

"If

a

well

is

pumped

for

a

known

period

and

then

left

to

recover,

the

residual

drawdown

at

any

instant

will

be

the

same

as

if

pumping

of

the the

well

had

been

continued

but

a

recharge

well

with

the

same

flow

had

been

introduced

at

the

same

point

at

the

instant

pumping

stopped."

Therefore,

the

coefficient

of

trans-

missibility

can

be

determined

from

the

rate

of

recovery

(as

well

as

the

rate

of

drawdown)

of

the

water

level

in

a

well.

Todd

(1959,

p.

97,

footnote)

stated,

"An

advantage

of

a

recovery

analysis

of

a

pumped

well

is

that

* * *

it

implies

a

constant

discharge

Q,

which

often

is

difficult

to

control

accurately

in

the

field."

The

coefficient

of

transmissi-

bility

of

the

aquifer

near

17

wells

was

determined

from

single-well

tests

(table

2),

page

33.

On

five

of

the

tests,

computations

were

made

from

the

rate

of

drawdown;

on

another

five,

computations

were

made

from

the

rate

of

recovery;

and

on

the

remaining

seven,

computations

were

made

from

both

the

rate

of

drawdown and

the

rate

of

recovery

(values

obtained

on each

well

by

both

methods

agreed reasonably

well).

Testing

aquifers

by

this

method

is

not

ideal,

but

much

useful

information

can

be

obtained.

Generally

the

storage

coefficient

cannot

be

determined

from

rate

of

drawdown

or

recovery

in

the

well

being

pumped,

because

the

effec-

tive

radius

of

the

well

is

not

known.

The

coefficient

of

storage

was

not

determined

from

any

of

these

tests.

SPECIFIC CAPACITY

The

specific

capacity

of

a

well

is

computed

by

dividing

the

discharge

from

a

well

by

the

drawdown.

The

specific

capacity

is

a

function

of

the

coefficients

of

transmissibility

and

storage

and,

therefore,

indicates

the

hydrologic

properties

of

the

aquifer.

Because

drawdown

is

not

only

dependent

on

the

water-yielding

properties

of

the

aquifer

but

also

on

the

well

construction

and

development,

the

relation

between

specific

capacity

and

coefficient

of

transmissibility

may

differ

from

well

GROUND

WATER

35

to

well

(table

2).

Actual

drawdown

is

greater

than

the

theoretical

drawdown

in

the

best

designed

and

constructed

wells

and

may

be

sev-

eral

times

as

great

in

poorly

constructed

and

poorly

developed

wells.

The

specific

capacity

decreases

with

increasing

discharge

and

with

in-

creasing

time.

Therefore,

using

the

specific

capacity

determined

from

a

short

pumping

test

to

predict

drawdown

after

a

long

period

of

pumping

and

(or)

after

pumping

at

a

different

rate

could

cause

some

large

errors.

Theis and

others

(1963,

p.

331-340)

outlined

a

method

for

esti-

mating

the

transmissibility

of

a

water-table

aquifer

near

a

well

of

known

specific

capacity.

They

noted

many

limitations

of

the

method

but

also

indicated its

usefulness

where

no

other

data

are

available.

This

method

was

used

in

the

Deer

Lodge

Valley

to

check

19

of

the

values

of

the

coefficient

of

transmissibility

obtained

from

aquifer

tests

and

to

estimate

the

coefficient

of

transmissibility

in

the

vicinity

of

11

other

wells

(table 3).

Of

the

19

values

checked,

four

were

the

same

as

TABLE

3.

Coefficient

of

transmissibility

values

estimated

from

specific

capacities

[Remarks:

T,

Tertiary

sediments;

A,

Quaternary

alluvium]

Well

B4-

9-31cb__...

10-10ac____.

17bd.__.

11-lcb

__

.

B5-ll-33cal-__

B6-10-

5aal

__.

B7-

9-

4ba.___.

20cc_

._.

10-

2cd

__

.

B8-

9-33cc.___.

10-23db___.

Specific

capacity

(gpm

per

ft)

0.6

3

13

1

50

26

40

13

2

30

.

5

Coefficient

of

trans-

missibility

(gpd

per

ft)

1,

000

5,000

20,

000

1,000

85,

000

40,

000

70,

000

20,

000

2,

000

50,

000

800

Remarks

T.

T(?).

A,

T(?).

Perforated

and

developed.

T.

A.

Perforated

and

developed.

A,

T.

Perforated

and

developed.

T.

Screened

and

developed.

T.

Screened

and

developed.

T.

those

obtained

from

pumping

tests,

six

were

reasonably

close,

and

nine

were

much

lower.

The

nine

were

low

because

they

were

from

specific

capacities

of

small-diameter

wells

with

unperf

orated

casings

that

have

large

entrance

losses.

The

estimated

values

(table

3)

for

perforated

or

screened

and

developed

wells

are

probably

correct

to

within

25

percent;

those

values

of

1,000

or

less

are

probably

correct

to

within

an

order

of

magnitude;

and

the

others are probably

some-

what

low.

SUMMARY

OF

HYDROLOGIC

PROPERTIES

The

principal

source

of

ground

water

in

the

Deer

Lodge

Valley

is

the

upper

few

hundred

feet

of

unconsolidated

and

semiconsolidated

valley

fill

of

Quaternary

and

Tertiary

age.

The

consolidated

rocks

of

36

GROUND-WATER

RESOURCES,

DEER

LODGE

VALLEY,

MONT.

the

surrounding

mountains

are

barriers

to

ground-water

movement

and

form

boundaries

along

the

sides

of

the

ground-water

basin.

The

alluvium

beneath

the

flood

plain

of

the

Clark

Fork

consists

chiefly

of

medium-

to well-sorted

unconsolidated gravel.

At

seven

aquifer

test

sites

(wells

B6-9-4ab,

B6-9-4bb,

B6-9-4cc,

B7-9-32da,

B8-9-15bal,

B8-9-21dal,

and

B8-9-21da2)

in

the

alluvium

the

co-

efficient

of

transmissibility

ranged

from

25,000

to

80,000

gpd

per

ft

(gallons

per

day

per foot).

Specific

capacities

ranged

from

6

to

36

gpm

per

ft

(gallons

per

minute

per

foot)

of

drawdown.

The

flood-

plain

alluvium

is

relatively

thin

and

is

not

extensive

laterally;

there-

fore,

the

yield

of

shallow

alluvial

wells

is

limited

to

a

few

hundred

gallons

per

minute

even

in

areas

of

high

transmissibility.

No

wells

were

found

in

the

moraine

deposits,

so

that

their

hydrologic

properties

are

not

known.

However,

the

lithology and

texture

of

the

moraine

deposits

indicate

that

the

transmissibility

would

generally

be

much

less

than

that

of

the

flood-plain

alluvium.

The

terrace

alluvium

on

the

west

side

of

the

valley

north

of

Dempsey

Creek

is

fairly

thin

and

most

of

the

wells

obtain

water

from

the

under-

lying

Tertiary

sediments.

However,

a

few

shallow

dug

wells

tapping

the

alluvium

along

draws

yields

adequate

water

for

stock

and

domestic

use.

The

alluvium

south

of

Dempsey

Creek

and

west

of

the

Clark

Fork

flood

plain

is

mostly

fan material

and

generally

much

thicker

than

the

alluvium

underlying

the

low

terrace. Adequate

water

for

domestic

and

stock

needs

can

be

obtained

from

these

deposits.

Sufficient

water

for

industrial

or

irrigation

needs

can

be

obtained

locally.

Transmissi-

bility

ranged

from

20,000

to

175,000

gpd

per

ft

for

the alluvium

in

this

area

as

determined

near

five

wells

(B4-10-15aal,

B5-10-l7dc,

B6-9-7ad2,

B6-9-7dc,

and B6-10-15aa)

and

estimated

from

the

spe-

cific

capacity

of

two

wells

(B4-10-llbd

and

B5-ll-33cal).

The

varia-

tion

is

due

to

differences

in

thickness

and

in

lithology.

Transmissibility

is

95,000,

20,000,

and

80,000

gpd

per

ft

near

three

wells

tapping

the

Quaternary

alluvium

and

Tertiary

sediments.

Data

indicate

that

much

of

the

water

comes

from

the

alluvium. A

transmissibility

of

40,000

gpd

per

ft

was

estimated

from

a

reported

specific

capacity

of

26

gpm

per

ft

of

drawdown

for

an

irrigation

well

(B6-10-5aal)

at

the

foot

of

the

Dempsey

Creek moraine.

The

owner's

report

indicates

that

the

well

is

probably

open

to

both

alluvium

and

Tertiary

sedi-

ments,

but

most

of

the

water

comes

from the

alluvium.

Two

other

wells

drawing

water

from

both

the

Quaternary

and

Tertiary

aquifers

be-

tween

Warm

Springs

Creek

and Mill

Creek

reportedly

yielded

800

and

1,200

gpm.

GROUND

WATER

37

The

relatively

small

deposit

of

alluvium

east

of

the

Clark

Fork

flood

plain

consists

mostly

of

fan

material

and

of

detrital

material,

which

was

formed

in

place

or

transported

a

short

distance.

No

aquifer

tests

were

made

in

this

deposit.

Some

water

is

obtained

from

shallow

dug

wells

in the

fan

material

of

Cottonwood

Creek

and

a

few

of

the

other

east-side

tributaries.

Yields

of

these

wells

are

reported

to

be

small

and

many

of

them

go

dry

in

early

spring.

No

wells

were

found

in

the

detrital

material

(alluvial

slope

wash)

in

the

southeast

part

of

the

valley.

As

recharge

to

this

area

is

only

from

precipitation,

it

is

doubt-

ful

that

any

large-yield

wells

could

be

obtained.

Adequate

water

probably

could

be

obtained

locally

for

stock

or

domestic

use.

The

Tertiary

sediments

that

yield

water to

wells

are

mostly

uncon-

solidated

to

semiconsolidated

fluvial

silt

and

interfingering

beds

of

unconsolidated

sand

and

gravel.

These sediments

are

generally

less

permeable

than

the

alluvium

but

have

a

much

greater

thickness.

Trans-

missibility

ranged

from

600

to

TO

,000

gpd

per

ft

as

determined

near

five

wells

(B5-10-24aa,

B7-9-17ad,

B8-9-15ab,

B8-9-27ac,

and

B9-9-34cc)

and

estimated

from

specific

capacities

for

8

wells

(B4~9-31cb,

B4-10-10ac,

B4-ll-lcb,

B7-9-4ba,

B7-9-20cc,

B7-10-2cd,

B8-9-33cc,

and

B8-10-23db).

Specific

capacities

ranged

from

less

than

1

to

40

gpm

per

ft

of

drawdown.

Eight

of

the

13

specific

capaci-

ties

were

less

than

10

gpm

per

ft

of

drawdown;

only

two

were

more

than

20

gpm

per

ft

and

both of

these

were

reported

specific

capacities

on

the

Deer

Lodge

municipal

wells.

Geologic

conditions

in

the

vicinity

of

Deer

Lodge

and

the

well

construction

indicate

that

a

high

specific

capacity

is

possible.

One

of

the

wells

reportedly

was

tested

at

1,300

gpm

with

32

feet

of

drawdown

after

24

hours

of

pumping.

WATER

TABLE

AND

MOVEMENT

OP

GROUND

WATER

The

water

table

is

an

irregular

sloping

surface

that

conforms

roughly

to

the

topography

and

rises

and

falls

as

the

aquifer

is

recharged

and

discharged.

The

water

table has

many

irregularities

that

are

caused

by

local

differences

in

permeability

and

local

and

seasonal

differences

in

withdrawals

from,

or

additions

to,

the

reservoir.

For

a

given

rate

of

ground-water

flow,

the

water-table

slope

will

be

relatively

gentle

if

the

transmitting

material

is

coarse

and

permeable,

such

as

a

clean

sand

and

gravel;

the

slope

will

be

steeper

if

the

material

is

fine

grained

and

less

permeable,

such

as

a

fine

sand

or

silty

sand

and

gravel.

The

slope

of

the

water

table

and

the

direction

of

movement

of

ground

water

were

determined

from

a

water-table

contour

map

made

from

measurements

in

June

1960

of

the

water

levels

in

159

wells.

Most

of

the

wells

in

the

northern

part

of

the

area

are

in

a

narrow

belt

along

the

Clark

Fork;

in

the

southern

part

they

are

in

a

wider

belt

but

are

38

GROUND-WATER

RESOURCES,

DEER

LODGE

VALLEY,

MONT.

mostly

on

the

west

side

of

the

Clark

Fork.

Therefore,

the

water-table

contours

could

only

be

drawn

for

part

of

the

area.

With

such

scant

data

many

of

the

details

of

the

shape

and

slope

of

the

water

table

could

not

be

shown

even

in

the

area

contoured

(pi.

1)

Ground

water

moves

downslope

perpendicularly

to

the

contours.

The

water-table

contour

map

shows

that

ground

water

moves

generally

toward

the

Clark

Fork,

but

in

detail

the

direction

of

movement

varies.

In

the

southwest

part

of

the

valley,

ground

water

moves

generally

northeast-

ward toward the

Clark

Fork;

but

it

has

a

component

of

flow

toward

Warm

Springs,

Dutchman,

Mill,

and Willow

Creeks.

The

slope

of

the

water

table in

this

part

of

the

area

averages

about

50

feet

per

mile.

Between

Racetrack

and

Lost

Creeks,

the

slope

of

the

water

table

is

generally

eastward

and

averages

about

70

feet

per

mile.

Data

are

insufficient

to

contour

the

water

table

on

the

east

side

of

the

river

or

in

the

northwestern

section

except

for

a

narrow

strip

along

the

Clark

Fork

in

the

northern

part.

The

topography

and

the

dip

of

the

Tertiary

beds

indicate

that

ground

water

east

of

the

river

moves

northwestward

and

ground

water

in

the

northwestern

section

moves

eastward.

The

quantity

of

water

that

flows

through

a

cross

section

of

the

aquifer

can

be

estimated

by

Darcy's

equation

written

in

the

form

(Ferris

and

others,

1962,

p.

73):

Q=TIL

(1)

where

Q=

discharge

in

gallons

per

day,

T=

coefficient

of

transmissibility

in

gallons

per

day

per

foot,

/=

hydraulic

gradient

in

feet

per

foot,

and

L=

width

in

feet

of

the

cross

section

through

which

the

discharge

occurs.

From

a

cross

section

along

the

5,050-foot

contour

line on

the

water

table

(pi.

1),

the

following

data

were

obtained.

The

length

of

the

section

across

the

coalescent

fans

between

Warm

Springs

and

Mill

Creeks

is

14,000

feet

and

the

slope

of

the

water

table

at

the

section

is

0.01

foot

per

foot.

The

coefficient

of

transmissibility

as

determined

from

an aquifer

test

on

well

B4-10-5ab

is

about

95,000

gpd

per

ft.

Substituting

these

values

in

equation

1:

#=95,000X0.01X14,000

=

13,000,000

gpd.

GROUND

WATER

39

The

velocity

at

which

ground

water

moves

can

be

determined

by

use

of

the

equation:

_

7ASeA

where

v=

velocity

in

feet

per

day,

Q=flow

through

the

cross

section

in

gallons

per

day,

6=

porosity

expressed

as

a

decimal,

and

A

cross-sectional

area

in

square

feet.

Assuming

a

thickness

m

of

100

feet,

the

area

of

the

cross

section

is

1,400,000

(Lm=

14,000X100)

square

feet.

The

estimated

porosity

is

40

percent.

Substituting

these

values

in

equation

2,

the

velocity

13,000,000

'

7.48X0.4X1,400,000

=3

feet

per

day.

Lower

values

of

transmissibility

more

than

offset

steeper

gradients

in

other

parts

of

the

study

area;

therefore,

the

ground-water

velocity

is

less

than

3

feet

per

day.

FLUCTUATIONS

OF

WATER

LEVEL

The

water

table

is

a

dynamic

surface.

Many

factors

cause

it

to

rise

or

fall.

The

most

important

factor

causing

water-level

fluctuations

in

the

Deer

Lodge

Valley

is

change

in

volume

of

water

in

the

ground-

water

reservoir.

The

amount

and

rate

of

fluctuation

depends

on

the

rate

of

loss

or

rate

of

replenishment

of

water

in

storage.

Ground

water

is

discharged

by

seepage

into

streams,

by

evaporation

and

transpira-

tion

(generally

along

streams),

and

by

pumping

from

wells.

This

dis-

charge

gradually

lowers

the water

table

except

when

exceeded

by

recharge

to

the

underground

reservoir

from

snowmelt,

precipitation,

and

seepage

from

streams

and

irrigation.

A

record

of

water-level

fluctuations

furnishes

valuable

information

about

discharge,

recharge,

and

storage.

Monthly

fluctuations

of

the

water

table

in

the

Deer

Lodge

Valley

were

measured

in

about

40

wells

in the

northern

part

of

the

valley

starting

in

the

fall

of

1957

and

in

about

45

wells

in

the

southern

part

of

the

valley

starting

in the

sum-

mer

of

1960.

Monthly

measurements

were

continued

in

most

of

these

wells

until

the

fall

of

1961,

when

two

measurements

per

year

(March

and September)

were

made

on

about

70

of

the

wells.

These

measure-

ments

will

be

continued

for

a

period

of

years

to

monitor

long-term

fluctuations.

Water-level

fluctuations

in

the

valley

may

be

placed

in

two

general

groups seasonal

and

long

term.

Seasonal

fluctuations

are

an

index

of

40

GROUND-WATER

RESOURCES,

DEER

LODGE

VALLEY,

MONT.

change

in

quantity

of

water

in

storage

during

the

year

and

long-term

fluctuations

indicate

trends

over

a

period

of

years.

Seasonal

fluctuations

indicate

the

amount

of

water

taken

into

or

released

from

storage.

In

general,

the water

level

in

the

valley

de-

clines

in

the

winter

and

early

spring,

then

rises

in late

spring

and

summer.

Hydrographs

indicate

that

location,

depth

to

water,

geologic

setting,

and

climatic

variations

affect

the

seasonal

fluctuations

(fig.

8).

The

time

of

the

annual

peak

varies

in

different

parts

of

the

valley

and

sometimes

varies

for

different

years

in

the

same

part

of

the

valley.

JFMAMJJASONPJFMAMJJASONDJFMAMJJASONDJFMAMJJASONDJFMAMJJASOND

1957 1958

1959 1960

1961

FIGURE

8. Effect

of

location,

depth

to

water,

and

geologic

setting

on

seasonal

fluctuations

of

the

water

level.

GROUND

WATER

41

During

the

period

of

record,

a

few

wells

reached

their

annual

peak

in

April

or

May;

most

of

the

wells

reached

the

annual

peak

in

June

or

July;

several,

in

August

or

September; and

a

few,

in

October

or

November.

Well

B6-9-4bb

(fig.

8)

is

in

the

alluvium,

and

wells

B6-10-lad

and

B7-9-31db

are

in

Tertiary

sediments

on

the

west

side

of

the

valley.

The

difference

in

the

time

of

the

annual

peak

is

caused

mostly

by

(1)

the

difference

in

depth

to

water

in

the

wells,

(2)

the

difference

in

sediment

size

and

bedding

of

the

material

between

the

source

of

recharge

and

the

water

table,

and

(3)

different

amounts

of

local

irrigation.

Gen-

erally,

water

levels

in

the

Tertiary

sediments

peak

later

than

water

levels

in

the

alluvium.

The

hydrograph

for

well

B5-9-6dc

shows

the

water

level

rising

from

September

through

April

and

declining

from

May

through

September.

This

is

fairly

typical

of

a

few

shallow

ob-

servation

wells

in

areas

of

high

water

table

and

is

due

to

evapotrans-

piration.

At

this

particular

well,

alkali

also

indicates

considerable

evaporation.

Water-level

flunctuations in

well

B4r-10-15aa also

show

the

effect

of

evapotranspiration.

In

addition,

they

show

that

recharge

during

May

was

more

than

enough

to

offset

the

discharge

by

evapo-

transpiration

and

underflow.

Well

B4-ll-lbb

is

near

Warm

Springs

Creek,

and

recharge

from

spring

runoff

causes

a

rapid

rise

in

the

water

level

in

May

and

a

continued rise

in

June.

Upstream

storage

and

utilization

of

almost

the

entire

low

flow

of

Warm

Springs

Creek

causes

a

rapid

decline

in

July

and

August.

Recharge

is

about

equal

to

dis-

charge

from

November

through

April.

Well

B4-9-31bd

is

artesian

and

reflects

the

local

fluctuation

of

the

piezometric

surface

of

the

base-

ment

rocks.

The

fairly

constant

rate

of

decline

from

October

through

May

is

not

general

throughout

the

valley.

Long-term

fluctuations

in

well

B7-10-3dd,

which

taps

Tertiary

sedi-

ments,

show

a

continued

and

substantial

decline

in

the

annual

peak.

The

decline

is

probably

caused

mostly

by

a

decrease

in

the

amount

of

irrigation

in

the

vicinity

because

less

than

20

acre-feet of

water per

year

(operator's

estimate)

are

pumped

from

the

only

well

in

the

vicinity.

Water-level

fluctuations

in

73

wells

were

used

to

estimate

the

monthly

change

in

ground-water

storage

for

the

period

June

through

September

1961.

The

valley

fill

was

divided

by

Thiessen

polygons

(Thiessen,

1911,

1082-1084)

so

that

each

polygon

contained

only

one

well

and

any

point

in

the

polygon

was

nearer

to

the

enclosed

well

than

any

other

well.

The

areas

of

the

polygons

were

determined

by

a

pla-

nimeter.

The

measured

monthly

change

in

water

level

in

each

well

was

multiplied

by

the

area

of

the

polygon

encompassing

the

well,

and

the

product

was

considered

to

be

the

bulk

volume

of

material

saturated

42

GROUND-WATER RESOURCES,

DEER

LODGE

VALLEY,

MONT.

or

drained

within

the

polygon

during

the

month.

The

sum

of

the

vol-

umes

for

all

polygonal

areas

in

the

valley

was

considered

to

be

the

total

bulk

volume

of

material

saturated

or drained.

Monthly

changes

in

the

volume

of

ground water

in

storage

were

computed

by

multiplying the

monthly

changes

in

volume

of

saturated

material

by

an

estimated

specific

yield

(0.1)

of

the

material.

These

changes

in

storage

are

dis-

cussed

under

the

section

on

discharge,

RECHARGE

The

Deer

Lodge

Valley

ground-water

reservoir

is

recharged

by

infil-

tration

of

water

from

irrigation,

precipitation

and

snowmelt

runoff,

and

influent

streams.

The

Clark

Fork

is

normally

an

effluent

stream,

but

for

a

short

period

during

the

spring

runoff

it

rises

high

enough

so

that

some

water

recharges

the

ground-water

reservoir.

Much

of

the

water,

which

is

diverted

from

the

Clark

Fork

to

irrigate

5,000

acres

of

land

in

the

valley,

percolates

into

the

ground-water

reservoir.

Most

of

the

major

tributaries

to

the

Clark

Fork

in

the

valley

are

perennial

in

their

upper

reaches,

but

during

the

summer

the

water

is

all

diverted,

leaving

the

streams

dry

for

much

of

their

course

across

the

valley.

Some

of

the

streams

flow

in

their

lower

reaches.

From

June

to

Sep-

tember

1961

about

16,000

acre-feet

of

water

was

diverted

from

Warm

Springs

Creek

for

industrial

use.

Total

flow

in

the

creek

for

the

same

period

was

about

24,000

acre-feet.

Total

flow

in

the

other

tributary

streams

was

about

50,000

acre-feet,

most

of

which

was

diverted

for

the

irrigation

of

30,000

acres

of

land.

In

addition,

about

13,000

acre-

feet

of

water

was

imported

to

the

area

from Eock

Creek

to

irrigate

about

4,000

acres

of

land.

Some

of

the

water

diverted

for

industrial

uise

and

much

of

the

water

diverted

for

irrrigation

percolates

to

the

ground-water

reservoir.

Most

of

the

tributary

streams

are

influent

for

at

least

part

of

their

course

across

the

valley;

therefore,

when

all

the

water

is

not

being

diverted,

they

become

effective

sources

of

recharge

to

the

underlying

and

adjacent

sediments.

Recharge

from

precipitation

and

snowmelt

is

governed

by

amount,

distribution

and

intensity

of

precipitation;

topography;

permeability

and

moisture-holding

capacity

of

the

surficial

deposits;

consumptive

use

through

evapotranspiration;

and

the

capacity

of

the

ground-water

reservoir

to

store

additional

water.

Probably

very

little

of

the

precipi-

tation

and

only

a

small

amount

of

the

snowmelt

is

recharged

in

the

nonirrigated

part

of

the

valley;

most

of

the

available

moisture

in

that

area

is

transpired

by

plants

or

evaporated.

The

average

annual

pre-

cipitation

is

about

10

or

11

inches.

Almost

one-third

of

the

total

nor-

mally

is

in

May

and

June,

which

are

also

the

months

of

high

recharge

from,

irrigation,

so

that

it

is

impossible

to

tell

from

the

hydrographs

GROUND

WATER

43

how

much

of

the

recharge

is

from

precipitation

and

snowmelt.

It

is

probably

small

in

comparison

to

the

amount

of

recharge

from

irriga-

tion.

Estimates

made

from

U.S

Weather

Bureau

records

indicate

that

precipitation

adds

about

150,000

acre-feet

of

water

per

year

to

the

valley.

Estimates

made

from

water-level

fluctuations

(p.

41,

44),

indi-

cate

a

net

increase

in

ground-water

storage

of

about

14,000

acre-feet

in

June

1961

and

about

1,500

acre-feet

in

July

1961.

DISCHARGE

Ground

water

is

discharged

from

the

Deer

Lodge

Valley

by

effluent

seepage

into

streams,

drains,

springs,

and

seeps;

by

evaporation

and

transpiration;

and

by

pumping

water

from

wells.

At

places

where

the

water

table

intersects

the

land

surface,

ground

water

is

discharged

by

effluent

seepage.

During

most

of

the

year

the

Clark

Fork

is

an

efflu-

ent

stream

throughout

the

valley.

Some

of

the

tributary

streams

(notably

Lost,

Dutchman,

Warm

Springs,

and

Willow

Creeks)

are

effluent

in

their

lower

reaches.

Streamflow

measurements

made

April

25,

1961,

showed

inflow

to

the

area

was

about

190

cfs

and

outflow

from

the

area

was

about

330

cfs.

Ground-water

discharge

to

the

streams

accounted

for

more

than

40

percent

of

the

total

outflow

from

the

area

on

that

day.

Measurements

of

the

flow

in Lost,

Dutchman,

Warm

Springs,

and

Willow

Creek

during

late

April

and

early

May

indi-

cated

that

more

than

70

cfs

of

ground

water

was

being

discharged

into

these

streams

during

that

period.

Much

of

the

ground-water

discharge

into

Willow

Creek

(20

cfs

on

May

19,1961)

was

from

an

8-mile

tile

drainage

system

in

the

vicinity

of

Opportunity.

The

system was

installed

about

1913

and

much

of

it

is

no

longer

effective.

Local

residents

reported

that

many

of

the

12-

inch

main

lines

carried

about

100

inches

(2.5

cfs)

of

water

for

many

years

after

the

system

was

installed.

One

outlet

measured

May

19,

1961,

was

discharging

1.7

cfs.

Most

of

the

other

outlets

discharge

directly

into

Willow

Creek

or

into

short

tributaries

of

Willow

Creek

that

probably

flow

because

of

water

surfacing

as

a

result

of

a

plugged

drain.

Farmers

and

ranchers

in

the

valley

have

dug

about

25

drainage

ditches.

The

drains

have

a

total

length

of

about

9

miles

and discharge

an

estimated

28

cfs

of

water

into

the

Clark

Fork

through

tributary

stream

channels

(H.

N.

Smets,

U.S. Soil

Conserv.

Service,

written

commun.,

Oct.

31

and

November

14,

1961).

A

3-mile

open

drain

in-

stalled

by

the Anaconda

Copper

Mining

Co.,

north

of

some

newly

constructed

settling

ponds,

was

discharging

about

7

cfs

on

May

5,1961.

A

similar

drain

south

of

the

settling

ponds

was

reported

to

have an

average

discharge

of

8

cfs

(John

Grant,

Anaconda

Copper

Mining

Co.,

44

GROUND-WATER

RESOURCES,

DEER

LODGE

VALLEY,

MONT.

oral

commun.,

1961).

It

also

discharges

tailings

water

from

the

Washoe

Smelter.

Discharge

of

ground

water

from

springs

and

seeps

is

small

in

com-

parison

to

discharge

by

effluent

streams

and

drains.

Three

thermal

springs Gregson

Hot

Springs,

Warm

Springs,

and

the

Anaconda

Hot

Springs discharge

several

hundred

gallons

per

minute

and

are

the

largest

springs

in

the

valley.

A

substantial

amount

of

water

is

discharged

from

the

valley

by

evapotranspiration

from

swamps,

from

areas

where

the

water

table

is

within

a

few

feet

of

land

surface

during

much

of

the

year,

and

from

many borrow

pits

that

are

partly

filled

with

ground

water.

A

large

quantity

of

water

is

also

discharged

from

the

area

by

evaporation

from

the

several

thousand

acres

of

settling

ponds

at

the

Washoe

Smelter

and

from

the

open

streams.

An

estimate

of

water

"use"

(evapotranspiration

and

change

in

soil-

moisture

storage)

from

June

to September

1961

(table

4)

was

made

from

inflow

and

outflow

records,

precipitation

records,

and

change

in

ground-water

storage

estimates.

Inflow

measurements

consisted

of

miscellaneous

measurements

of

eight

streams

and

two

irrigation

canals

(table

5)

and

continuous

streamflow

records

on

German

Gulch,

Racetrack

Creek,

and

Warm

Springs

Creek.

Streamflow

records

of

Warm

Springs

Creek

were

furnished

by

the

Anaconda

Copper

Min-

ing

Co.

The

outflow

was

determined

from

daily

gage

heights

and

monthly

discharge

measurements

of

the

Clark

Fork

near

Garrison.

From

June

to

September

1961,

the

total

"use"

(125,000

acre-feet)

was

more

than

three

times

as

much

as

the

total

discharge

from

the

area

as

streamflow

(41,00

acre-feet).

The amount

of

ground

water

discharged

by

pumping

from

wells

is

relatively

small

in

comparison

to

the

amount

discharged

by

effluent

streams

and

evapotranspiration.

About

7,000

acre-feet

of

water

per

year

is

pumped

from

the

ground-water

reservoir.

TABLE

4.

Monthly

water

supply

of

the

Deer

Lodge

Valley,

in

acre-feet,

for

the

period

June-September

1961

Month

July..

--__-

Sept.

.......

Surface-

water

inflow

51,100

20,500

14,300

12,100

Surface-

water

outflow

19,

600

6,000

5,100

10,300

Net

loss

in

stream-

flow

31,

500

14, 500

9,200

1,800

Precipita-

tion

18,900

17,100

6,700

28,

700

Ground-

water

discharge

8,700

3,200

Ground-

water

recharge

13,700

1,300

Evapotrans-

piration

and

change

in

soil-moisture

storage

36,

700

30,

300

24,600

33,

700

Total.........

98,000 41,000

57,000

71,400 11,900

15,000

125,300

TABLE

5.

Miscellaneous

streamflow

measurements,

Deer

Lodge

Valley,

1961

[Values

are

in

cubic

feet

per

second]

Date

May

29___---_.

_____.__-

June

19_________________..

July

18

July

31-_____.

...........

Aug.

16....._.

..........

Aug.

28..

_______________

Sept.

6-------___________

Sept.

15.___._______._._.

Clark

Fork

(near

Ramsey)

.......___

38.81

.-_..____-

27.42

__________

31.14

..........

25.88

20.81

..........

30.75

__________

29.43

..........

27.47

._.___._..

25.86

__.

..........

22.39

__......._

26.45

...

__________

25.23

__________

25.07

___._.-_._

25.73

..........

24.97

Willow

Creek

40.79

20.73

18.91

9.54

6.92

5.31

3.68

2.34

.84

1.13

1.53

1.50

1.78

Mill

Creek

177.68

192.97

181.66

91.88

67.14

43.30

45.90

38.39

19.17

15.96

14.42

13.05

17.05

18.46

19.83

Lost

Creek

46.72

40.32

44.93

21.79

18.13

16.44

.___

14.02

12.89

10.90

10.48

7.27

7.56

8.48

7.72

6.89

Modesty

Creek

4.95

7.20

6.58

6.54

5.92

5.70

4.11

4.76

3.37

3.59

3.20

3.73

3.61

3.16

Dempsey

Creek

55.36

65.23

57.86

47.56

42.74

28.81

22.93

19.29

11.18

7.03

9.44

10.65

10.70

7.34

8.93

Peterson

Cottonwood

Creek

11.

31

161. 77

4.08

61.20

1.

79 31.

19

.

58 19.

33

<.5

8.37

<.5

4.76

<.

5

3.

75

<.5

2.11

<.5

2.70

<.5

1.51

<.5

4.93

<.5

5.89

Tincup

Creek

33.08

32.33

26.47

20.34

16.62

8.85

8.65

5.81

...

5.55

4.04

__.

4.97

...

6

/i

i

Tavener

Ditch

33.99

66.43

56.61

33.39

Q4.

QQ

31.34

35.64

33.44

12.10

10.48

Pauly

Ditch

45.59

49

59

33.40

31.46

OQ

Q7

52.59

Qfl

QO

5.23

Cn

46

GROUND-WATER

RESOURCES,

DEER

LODGE

VALLEY,

MONT.

PRESENT

DEVELOPMENT

In

the

Deer

Lodge

Valley,

ground

water

is

the principal

source

of

water

for

municipal

and

domestic

use.

Only

two

wells

are

presently

(1967)

being

used

for

irrigation, but

three

others

have

been

drilled

that

will

probably

be

used

for

irrigation

in

the

future.

About

7,000

acre-feet

per

year

of

ground

water

is

pumped

from

six

municipal,

four

State

institution,

two

irrigation,

and

several

hundred

domestic

and

stock

wells.

Almost

50

percent

of

the

7,000

acre-feet

is

pumped

from

three

municipal

wells

in

Anaconda;

another

30

percent

is

pumped

from

three

municipal

wells

in

Deer

Lodge.

The

wells

in

Anaconda

tap

alluvium

along

Warm

Springs

Creek.

Two

of

the

Deer

Lodge

wells

tap

Tertiary

sediments;

the

other,

a

shallow

well

used

mostly

for

standby,

taps

alluvium

along

the

Clark

Fork.

Total

pumpage

from

four

State

institution

wells

is

about

1,000

acre-

feet

per

year;

most

of

the

water

is

from

Tertiary

sediments.

Probably

less

than

300

acre-feet

per

year

is

withdrawn

from

stock

and

domestic

wells

tapping

alluvium

and

Tertiary

sediments.

About

200

acre-feet

per

year

is

pumped

from

two

irrigation

wells.

The

three

unused

irri-

gation

wells

are

capable

of

yielding

'almost

500

acre-feet

each

irriga-

tion

season.

Most

of

the

water

from the

irrigation

wells

in

use

is

from

Tertiary

sediments,

but

water

from

the

other

three

will

be

mostly

from

Quaternary

sediments.

POTENTIAL

DEVELOPMENT

Because

the

entire

flow

of

all

the

tributary

streams

rising

in

the

mountains

and

flowing

into

the

Deer

Lodge

Valley

is

appropriated,

any

future

developments

that

require

substantial

amounts

of

water

will

have

to

use

ground

water

or

purchase

surface-water

rights.

Recharge

to

the

valley

fill

is

sufficient

that

additional

withdrawals

of

ground

water

could

be

made

without

excessively

lowering

the

water

table.

Because

of

the

great

variation

of

water-yielding

properties

of

the

sediments

in

different

parts

of

the

valley,

test

holes

should

be

drilled

before

installation

of

industrial

or

irrigation

wells.

The

most

likely

areas

for

the

best

wells

are

in

the

flood

plain

of

the

Clark

Fork

and

coalescing

fans of

Mill

and

Warm

Springs

Creeks.

In

these

areas,

properly

constructed

and

developed

wells

will

yield

as

much

as

300

gpm

if

they

penetrate

alluvium

with

a

large

saturated

thickness.

Properly

constructed

and

developed

wells

tapping

both

the

Quater-

nary

and

Tertiary

sediments

will

yield

1,000

gpm

or

more.

Wells

with

the

greatest

yield

from

the

Tertiary

sediments

are

gravel

packed.

Gravel

packing

is

generally

not

necessary

in

the

Quaternary

sediments.

Wells

that

will

yield

300

gpm

or

more

can

be

developed

in the

Race-

track

and

Dempsey Creek

fans.

Because

of

the

variation

in

saturated

GROUND

WATER

47

thickness

and

sediment

size,

test

holes

should

be

drilled

before

the

drilling

of

production

wells.

The

Tertiary

sediments

underlying

these

fans

are

predominently

fine

grained

and

do

not

yield

sufficient

water

to

wells

for

irrigation.

In

the rest

of

the

valley,

the

upper

few

hundred

feet

of

sediments

will

generally

yield

water

sufficient

only

for

stock

and

domestic

use.

However,

there

are

some

aquifers

at

greater

depths.

A

test

hole

(B7-

10-22dd)

drilled

by

the

Montana

Power

Co.

reportedly

flowed

140

gpm

from

a

depth

of about

1,200

feet.

The

sodium

content

is

great

enough

that

the

water

is

probably

not

suitable

for

irrigation

of

most

soils

(U.S.

Soil

Conservation

Service,

Bozeman,

Mont.,

written

commun.

March

21,

1962).

The water

would

probably

be

suitable

for

certain

industrial

uses

or

for

public

supply.

SUMMARY

AND

CONCLUSIONS

The

principal

aquifers

in

the

Deer

Lodge

Valley

are

in

the

upper

few

hundred

feet

of

valley

fill,

which

includes

sediments

of both

Quaternary

and

Tertiary

age.

The

Quaternary

alluvium

is

relatively

thin;

but

domestic

and

stock

wells

obtain

sufficient

water

except

along

minor

tributary

streams.

Locally,

water

for

irrigation

of

small

areas

can

be

obtained

from

the

alluvium

in

the

vicinity

of

the

Clark

Fork

and

its

major

tributaries.

The

Tertiary

sediments

are

thick; their

permeability

is

variable

but

generally

low.

Most

wells

in

the

Tertiary

sediments

yield

less

than

10

gpm

per

ft.

of

drawdown

even

when

properly

constructed

and

developed.

However,

the

thickness

of

these

sediments

is

great

enough

that

yields

of

1,000

gpm

or

more

can

be

ob-

tained

locally.

The

most

likely areas

for

obtaining the

higher

yielding

wells

are

the

flood

plain

of

the

Clark

Fork

and

the

coalescing

fans

of

Mill

and

Warm

Springs

Creeks.

Recharge

in

the

valley

is

sufficient

that

additional

withdrawals

of

water

could

be

made

without

exces-

sively

lowering

the

water

table.

The

depth

to

water

in

the

flood-plain

area

is

generally

less

than

10

feet,

but

on

the

fans and

terraces

it

ranges

from

10

to

150

feet.

Depth

of

wells

ranges

from

a

few

feet

to

250

feet.

The

general

direction

of

movement

of

ground

water

in

the

valley

is

toward

the

flood-plain

from

the

east

and

west.

However,

in

the

southwestern

part

of

the

valley,

movement

of

ground

water

is

generally

northeastward

with

a

compo-

nent

of

flow

toward

the

tributary

streams.

48

GROUND-WATER

RESOURCES, DEER

LODGE

VALLEY,

MONT.

SELECTED

REFERENCES

Alden,

W.

C.,

1927,

Western

Montana

and

adjacent

areas,

in

Studies

of

glacial

sediments

in

1927 Report

of

Committee

on

Sedimentation

1927-28:

[U.S.]

Natl.

Research

Council

reprint

and

circulation

series,

no.

85, p.

56-57.

1953,

Physiography

and

glacial

geology

of

western

Montana

and

adjacent

areas:

U.S.

Geol.

Survey

Prof.

Paper

231,

200

p.

Baadsgaard,

H.,

Folinsbee,

R.

E.,

and

Ldspson,

U.,

1961,

Potassium-argon

dates

of

biotite

from

Cordilleran

granites:

Geol.

Soc.

America

Bull.,

v.

72,

no.

5,

p.

689-702,

Billingsley,

Paul,

1913,

The

Boulder

batholith

of

Montana:

Am.

Inst.

Mining

Engineers Trans.,

v.

51,

p.

31-56.

Calkins,

F.

C.,

and

Emmons,

W.

H.,

1915,

Description

of

the

Philipsbttrg

quad-

rangle,

Montana:

U.S.

Geol.

Survey

Geol.

Atlas,

Folio

196,

p.

11.

Campbell,

M.

R.,

1915,

The

Northern

Pacific

route,

with

a

side

trip

to

Yellow-

stone

Park,

Part

A

of

Guidebook

of

the

western

United

States:

U.S.

Geol.

Survey

Bull.

611,

p.

111-114.

Chapman,

R.

W.,

Gottfried,

D.,

and

Waring,

C.

L.,

1955,

Age

determinations

of

some

rocks

from

the

Boulder

batholith

and

other

batholiths

of

western

Mon-

tana

:

Geol.

Soc.

America

Bull.,

v.

66,

no.

5,

p.

607-609.

Csejetey,

Be'la,

1962,

Geology

of

the

southeast

flank

of the

Flint

Creek

Range,

western

Montana:

Princeton,

N.J.,

Princeton

Univ.,

Ph.

D.

thesis,

175

p.

Douglass,

Earl,

1901,

Fossil

Mammalia

of

the

White

River

beds

of

Montana:

Am.

Philos.

Soc.

Trans.,

new ser.,

v.

20,

p.

247-279.

Fenneman,

N.

M.,

1931,

Physiography

of

western

United

States:

New

York,

McGraw-Hill

Book

Co.,

Inc.,

534

p.

Ferris,

J.

G.,

Knowles,

D.

B.,

Brown,

R.

H.,

and

Stallman,

R.

W.,

1962,

Theory

of

aquifer

tests:

U.S.

Geol.

Survey

Water-Supply

Paper

1536-E,

p.

69-174,

flgs.

17-45.

Hammer,

Sigmund,

1939,

Terrain

corrections

for

gravimeter

stations:

Geo-

physics,

v.

4,

p.

184-194.

Jacob,

C.

E.,

1947,

Drawdown

test

to

determine

effective

radius

of

artesian

well:

Am.

Soc.

Civil

Engineers

Trans.,

v.

112,

p.

1047-1070.

Jennings,

O.

E.,

1920,

Fossil

plants

from

the

beds

of

volcanic

ash

near

Missoula,

western

Montana:

Carnegie

Mus.

Mem.,

v.

8,

no.

2,

p.

385-450.

Knopf,

Adolph,

1953,

Geology

of

the

northern

portion

of

the

Boulder

batholith,

Montana

[abs.]

:

Geol.

Soc.

America

Bull.,

v. 64,

no.

12,

pt.

2,

p.

1547-1548.

Konizeski,

R.

L.,

1957,

Paleoecology

of

the

middle

Pliocene

Deer

Lodge

local

fauna,

western

Montana

:

Geol.

Soc.

America

Bull.,

v.

68,

p.

131-150.

Konizeski,

R.

L.,

McMurtrey,

R.

G.,

and

Brietkrietz,

Alex,

1961,

Preliminary

report

on

the

geology

and

ground-water

resources

of

the

northern

part

of

the

Deer

Lodge Valley,

Montana:

Montana

Bur.

Mines

and

Geology

Bull.

21,

24

p.

1962,

Preliminary

report

on

the

geology

and

ground-water

resources

of

the

southern

part

of

the

Deer

Lodge Valley,

Montana

:

Montana Bur.

Mines

and

Geology

Bull.

31,

24

p.

MacGinitie,

H.

D.,

1953,

Fossil

plants

of

the

Florissant

beds,

Colorado:

Carnegie

Inst.

Washington

Pub.

599,

198 p.

SELECTED

REFERENCES

49

Meinzer,

O.

E.,

1923a,

The

occurrence

of

ground

water

in

the

United

States,

with

a

discussion

of

principles:

U.S.

Geol.

Survey

Water-Supply

Paper

489,

321

p.

1923b,

Outline

of

ground-water

hydrology,

with

definitions:

U.S.

Geol.

Survey

Water-Supply

Paper

494,

71

p.

Mutch,

T.

A.,

1960,

Geology

of

the

northeast

flank

of

the

Flint

Creek

Range,

Montana

:

Princeton,

N.

J.,

Princeton

Univ.,

Ph.

D.

thesis,

159

p.

Nettleton,

L.

L.,

1940,

Geophysical

prospecting

for

oil:

New

York,

McGraw-Hill

Book

Co.,

Inc.,

446

p.

Pardee,

J.

T.,

1913,

Coal

in

the

Tertiary

lake

beds

of

southwestern

Montana:

U.S.

Geol.

Survey

Bull.

531-G,

p.

229-244.

1950,

Late

Cenozoic

block

faulting

in

western

Montana

:

Geol.

Soc.

America

Bull.,

v.

61,

no.

4,

p.

359-406.

1951,

Gold

placer

deposits

of

the

Pioneer

district,

Montana:

U.S.

Geol.

Survey

Bull.

978-C,

p.

69-99.

Perry,

E.

S.,

1933,

Possibilities

of

ground-water

supply

for

certain

towns

and

cities

of

Montana

:

Montana

Bur.

Mines

and

Geology

Misc.

Contr.

2,

p.

13-14.

1934,

Physiography

and

ground-water

supply

in

the

Big

Hole

Basin,

Montana

:

Montana

Bur.

Mines

and

Geology

Mem.

12,18

p.

Poulter,

G.

J.,

1957,

Geology

of

the

Georgetown

thrust

area

southwest

of

Philips-

burg,

Montana:

Princeton,

N.J.,

Princeton

Univ.,

Ph.

D.

thesis,

279 p.

Ruppel,

E.

T.,

1957,

Geology

of

the

Basin

quadrangle,

Montana:

U.S.

Geol.

Survey

open-file

rept.

437,

219 p.

1961,

Reconnaissance

geologic

map

of

the

Deer

Lodge

quadrangle,

Powell,

Deer

Lodge

and

Jefferson

Counties,

Montana:

U.S.

Geol.

Survey

Mineral

Inv.

Field

Studies

Map

MF-174.

1963,

Geology

of

the

Basin

quadrangle,

Jefferson,

Lewis

and

Clark,

and

Powell

Counties,

Montana

:

U.S.

Geol.

Survey

Bull.

1151,121

p.

Smedes,

Harry

W.,

1962,

Lowland

Creek

Volcanics,

an

upper

Oligocene

formation

near

Butte,

Montana

:

Jour.

Geology,

v.

70,

no.

3,

p.

255-266.

Smedes,

H.

W.,

and

Thomas,

H.

H.,

1965,

Reassignment

of

the

Lowland

Creek

Volcanics

to

Eocene

age

:

Jour.

Geology,

v. 73,

no.

3,

p.

508-509.

Theis,

C.

V.,

1935,

The

relation

between

the

lowering

of

the

piezometric

surface

and

the

rate

and

duration

of

discharge

of

a

well

using

ground-water

storage:

Am.

Geophys.

Union

Trans.,

v.

16,

pt.

2,

p.

519-524.

Theis,

C.

V.,

Brown,

R.

H.,

and

Meyer,

R.

R.,

1963,

Estimating

the

transmissibility

of

aquifers

from

the

specific

capacity

of wells,

in

Methods

of

determining

permeability,

transmissibility,

and

drawdown:

U.S.

Geol.

Survey

Water-

Supply

Paper

1536-1,

p.

331-340.

Thiessen,

A.

H.,

1911,

Precipitation

averages

for large

areas:

Monthly

Weather

Rev.,

v.

39,

p.

1082-1084.

Todd,

D.

K.,

1959,

Ground

water

hydrology:

New

York,

John

Wiley

&

Sons,

Inc.,

336

p.

Weeks,

R.

A.,

and

Klepper,

M.

R.,

1954,

Tectonic

history

of

the

northern

Boulder

batholith

[abs.]

:

Geol.

Soc.

America

Bull.,

v.

65,

no.

12,

pt.

2,

p.

1320-1321.

Wood,

A.

E.,

1936,

Geomyid

rodents

from

the

middle

Tertiary:

Am.

Mus.

Novitates

866,

31

p.

Wood,

A.

E.,

and

Konizeski,

R.

L.,

1965,

a

new

Eutypomyid

rodent

from

the

Arikareean

(Miocene)

of

Montana:

Jour.

Paleontology,

v.

39,

no.

3,

p.

492-496.

INDEX

[Italic

page

numbers

indicate

major

references]

Page

2

15

26

12

Acknowledgments__..........._.......

Age,

Cretaceous......._......___...

Eocene,

early.................._...

middle..______._...........

Mesozoic....._.................._.

Miocene................___........_

13,26

early.....__....._...._....._.

16

late...................................

16

middle............_................

16

Oligocene,

late............................

12

Pleistocene,

early._.....................

21,27

Pliocene.-..._.........................

26

late...................................

27

Precambrian..................._.......

12

pre-Miocene_.........._..............

13

pre-

Wisconsin..........._..............

21

Quaternary_._........................

35,47

Tertiary ............................

13,35,47

early.._............................

12

late...................................

15

middle...............................

12,15

Wisconsin,

early.._.....................

21

Agriculture_................................

11

Alluvium ..................................

41,46

flood-plain__...........................

27,36

Quaternary......................

13,17,22,36,47

Recent........._.......................

27

terrace. .........................._..

36

Alnus

microdentoides....

......................

15

Anaconda,

Mont_..

.......-.-.........

11,24,46

Anaconda

flora...............................

15

Anaconda

Hot

Springs...._......_.......

24,44

Anaconda

Range.............................

21

Andesite

flows__........__...............

29

Andesitic

rocks...............................

13

Anticlines....................................

24

Appropriation,

surface

water.................

46

Aquifers,

defined....................._.....

30

principal................._.............

47

Quaternary...............................

36

Tertiary..................................

36

tests..................................

32,34,38

Artesian

aquifer..............._............

31

defined...............__........_.....

30

well......................................

41

Ash,

volcanic_.._..........__..........

26

B

Basement

rocks.....................

12,22,24,27,41

Basin,

structural................__......_

24

Basin

quadrangle_.........................

26

Batholith,

Boulder.....................

13,14,22,25

Philipsburg..............................

12,14

Page

15

38

Beds,

Eocene_....._...-.-.--

-......-

Miocene_...._..........._.......

Oligocene_......_.................

Pliocene......._._.__..........

Tertiary......._...........__.....

lower........_...._...............

17,24

middle...............................

17,24

Belt

quartzite,

boulders,

explanation

of

occur-

rence.............................

23

Bentonite...-.............-.-.-..-..-.....---

14

Bibliography.................................

48

Bison

Mountain._._._..................

7

Borrow

pits..................................

44

Boulder

batholith......................

13,14,22,25

Boulder

trains................................

20,27

Buffalo

Qlaciation............................

21

Bull

Lake.......-.......--.......-....---.-

21

Cenozoic

fill..................................

24

Channel

deposits.......................

17,19,22,26

Clark

Fork........

7,8,9,16,26,

27,37,38,42,43,46,47

at

Deer

Lodge,

mean

annual

flow_.

_.

9

fan.......................................

22

flood

plain.................

11,22,27,36,37,46,47

near

Garrison...__......................

44

Clastic

rocks..---.......-.-..-..--....-----.-

12,13

Cliff

Mountains..............................

7

Climate............._......................

9

Colluvmm...................................

17,26

Pliocene_...............................

17

Colorado

Shale...............................

13

Confined

water_.............._........_

31

Confining

bed,

defined............_........

30

Continental

Divide_._............_.....-...

7

Cottonwood

Creek.........._..............

17,37

fan.......................................

22

Cottonwood

village_.-.-...-..--.-......-..

11

crassigenis,

Prosthennops......................

20

Cretaceous

age...............................

15

Cretaceous

rocks..._..............___...

13,14

Lower_.......-....-.....-.--.-.--..-.--

12

middle..--...-.....--.....-.-.-..--.-----

12

Upper...................................

13

Culture......................................

11

D

Daly,

Marcus,

founder

of

copper

mining

in-

dustry,

Butte.......... .

....

11

Dates,

radiometric__.-.----.-.---...--.---.

15

Deer

Lodge

County......._.........

..

7

Deer

Lodge

flora.........___.............

15

51

52

INDEX

Deer

Lodge

Mountains__...................

Definitions,

selected

hydrologic

terms.....__.

Dempsey

Creek........................

14,21,

fan.....-._-.-.....--.-................._.

gravel

pit_______________________________

moraine.

.................................

Deposits,

channel--.--..--....-.----...

17,19,

fan-.-......-..._--....--..--...-...-.....

flood-plain.._........................

19,

Miocene,

lacustrine_.....--.......-.--.-

lower.

------------_..--........._.-...

moraine..

................................

Pliocene

--_.___-..-_....................

middle...............................

Quaternary..............................

sedimentary..............................

Tertiary..-.-.----......................-.

Depth

of

wells_............................

Depth

to

water_............................

Development,

potential___................

present...................................

Dikes........................................

Discharge..............................

38,39,

Dolomite.....................................

Domestic

use....--..-......-..-..-.....

36,37,

Dorf,

Erling,

fossil

identification_..........

Drainage..

--

---.---......-....-

ditches._...............................

open ..................................

tile......................................

Drains.......................................

Drawdown_................................

defined........-..-..---.................,

Drift.........................................

Dry

farming_..............................

Dug

wells....................................

Dutchman

Creek_.........................

Page

7

SO

25,36

46

17

27,36

,

22,

26

22

22,

26

25

12

gO,

21

14,22

14

12

41,43

12

46,47

15

9

43

44

32,34

30

21,24

11

36,37

38,43

E

Effluent

flow,

defined..

......................

30

Effluent

seepage

_

..--..-...-..-..-...-......

43

Effluent

streams...

........................

42,43,44

Eocene,

beds.

_

......

early,

age

_

.......

middle,

age

_

.....

rocks

-..--.....

Equisetum

^i>.

.........

Erosion,

Miocene,

late

Oligocene

_

.......

Pleistocene.

.......

Pliocene.-..-......

Erosion

scarp.

_

......

Erosional

cycles..

.....

Erratics...............

Evaporation

__

......

.................

15

.................

26

.................

12

..--.....-..-....

14

.................

14

-.....--.-..--.-.

26

.................

26

...--..-....--.--

26

.-..---...-......

26

.................

24

.................

27

.................

20

.....----.._.--..

43

Evapo

transpiration

__

......................

41,44

defined...................................

30

Fan,

Clark

Fork..._.......................

22

Cottonwood

Creek..-------..............

22

Fred

Burr

Creek............-.--.-.-.---.

22

glaciofiuvial..-_-..-.-..-.._--__---....

20,21,22

Lost

Creek...............-.---._._--.-.-.

22,24

Fan,

Clark

Fork Continued

Mill

Creek.__............ .--_..__.....

outwash...--.............-...--.....--...

Warm

Springs

Creek.....................

Farming,

dry.................................

Fault.....---....._...............----..-...-.

Mount

Powell ......................

24,

Faulting ......-..-...-..-.......-..--..-

24,

Fauna,

vertebrate............................

Fill,

Cenozoic.._...........................

maximum

depth

in

valley.------....--...

Miocene..................................

Pliocene..................................

Flint

Creek

Range.....

7,9,12,14,15,20,24,25,

Flood

plain,

alluvium........................

Clark

Fork......................

11,22,27,

deposits...--......-.-........----....-

19,

Flora,

Anaconda.............................

Deer

Lodge __.........................

Florissant................................

Missoula

Valley.

.......-.....-.-.....----

Flonssant

flora...............................

Flow,

mean

annual,

Clark

Fork

at

Deer

Lodge-

Flowing

well,

defined__......-.....-.-.-...

Flows,

andesite_.....--..-.......----.-----.

lava...--.............-..--..-.---..-----.

pyroclastic.

..............................

siliceous

_..--...............-.-.-.-----.

Folding--.--.-.-.-.----....-----------------.

Fossil

plants.....----..-..-.......-...--------

Fred

Burr

Creek

fan.........................

Frost,

killing.--_-__--._-.-___-__-----------.-

Page

22,24

20

22,24

11

29,30

25,29

25,26

16

24

30

25

26,29

27,36

36,37

22,26

15

9

30

13,29

29

13

24,25

15

22

G

Galen,

Mont.--............-.-.-------.------

11

Galen

gravel

pit..............................

17

Garrison,

Mont.............................

7,9,24

Garrison

Vent................................

13,16

Gazin,

C.

Lewis,

fossil

identification.

Geography.---...--.....-...-..-----

German

Gulch......................

Glacial

deposits.....................

Glacial-interglacial

periods__......

Glacier,

Racetrack

...................

20

7

44

20

27

21

Glaciofiuvial

fans..........................

20,21,22

Granitic

rocks.............................

12,13,14

Grant,

John

Francis,

early

settler ..-...--

11

Gravel

pit,

Dempsey

Creek........---...----

17

Galen..-.-..-.--.................--------

17

Pioneer...-........................-------

22

Powell

County-....-.......-.......----.-

17

Tri-City ---

.

---

22

Gravel

trains--.--....-.-.........------------

20

Gravimetric

survey.._......................

5,27

Gravity,

residual..................

.......

28

Gregson,

Mont..............-....--.---------

7,9

Gregson

Hot

Springs. ...............--

-.-

44

Ground

water.-.-..-.--.....-.--.------------

30

movement .......-...--..-..---------.-

37

occurrence

_............

_.......---.---

31

principal

source........-..-..-.----------

35

reservoir_................-....--

--.--

42

storage

estimates.........................

44

velocity

----.-...-..---..-..--.-----------

39

-INDEX

53

H

Tertiary

-

----..--

I

J

K

Kootenai

Formation.

............

L

Lateral

moraines.

...............

Lime.........

................

Limestone

formation,

Mesozoic..

Paleozoi

'....................

Little

Blackfoot

River.

..........

Lost

Creek............

.......

fan...

...................

.

Lowland

Creek

Volcanics

.......

M

Mammals,

Pliocene

..

...........

Manganese

precipitate

_

.......

Marsh

Creek...................

Mesozoic,

age...

..

...............

limestone

formation.

. .

.

__

.

rocks......

..........

......

Metamorphic

rocks.

_

.........

microdentoides,

Alnus...

.........

Mill

Creek......................

fan..........

...............

Miocene,

age...........

.........

beds...

......

...............

early,

age...................

vertebrate

fauna....

....

fill

......................

lacustrine

deposits..

.........

late,

age.

...................

erosion....

..............

lower,

deposits..

............

sediments

..............

middle,

age

_

...............

sediments.

..................

Missoula

Valley.....

....

.

......

.

flora...............

.

.....

Modesty

Creek

_

...............

Moraine,

Dempsey

Creek

.....

deposits.

..........

...

.......

Racetrack

Creek..

..........

1

Wisconsin.

.................

Page

.

..-

ll

.............

#7

.........

25

..........

36,42,47

---.

..-..

43,44

..-.

..-

30

.-..

42

--------

12

.

11,36,41,42,46,47

-_.-..._.._.

16,19

......._-_._.

13

-.-.

-...-

21

OQ

.............

19

.............

12

.............

14

--.--.--

14

.

-....-

9

9,

12, 15,

21, 27, 38,

43

.............

22,24

....

12,14,15,24,26

.--......-

20

.............

19

.

--.._.

20,25

.............

12

-------

14

..--...

12,14

--...--._

12

.............

15

.....

9,21,27,36,38

.......

22,24,46,47

.............

13,26

.............

15

.............

16

.............

16

.............

25

.............

25

.............

16

.............

26

.............

12

.............

16

.............

16

.............

13

.............

15

.............

15

.............

15,25

.............

27,36

..........

#0,21,27

.............

21,27

.............

27

-.-

....

21

........

8.21.22.27

fault.....

................

..

N

Northern

Rocky

Mountains

O

P

sediments-..-.-.-...-

Potassium-argon

determination

Precipitation

......

.............

highest.....

...............

lowest-

........--. -.

Pre-

Wisconsin

age.

.............

Principal

aquifers....

..........

Prosthennovs

crassiaenis.

.......

Page

..............

7

......

....

...

24,25

..-.....--13,16,27

..............

7

..

-

..

19

physiographic

-...-.

.-

7

..............

15

..............

26

.

......

12

..............

25

......

-43

.......

43,44

.

...........

20

--..

27

...

...........

14

......

--

26

on

........-

--

17

...............

12,14

.....

.........

17

99

......

21,27

15

.......--.--

17

14

22

25

97

.._...-...---

20

.

. .

......

.

14

97

.............

17

25

43 44

on

. .

......

27

.....

12

.

...

.......

7

.......

17

...

9,42,44

9

....-

9

21

......

47

20

54

INDEX

Page

Pumping..................................

32,43,44

Pyroclastic

rocks.............................

13

Q

Quartzite.....................................

12

Quaternary,

age______._________

35,47

alluvium........................

13,17,00,36,47

transmissibility,

coefficient

of..

___

32

aquifers...._______._______

36

deposits.____________.___

HO

history_______________.___

Vt

sediments..________________

46

R

Racetrack

Creek... ..............

14,21,27,38,44

fan... - .

-......

46

moraine.._._________.___

21,27

Racetrack

glacier_____.___.____

21

Radiometric

dates.______________

15,26

Recent

alluvium.....______ ..._

27

Recessional

moraines.------- . . _

21

Recharge

39,41,4«

Recovery,

defined.________ ......

30

rate...__

. _ ...

34

Robinson

Creek______________

14,24,27

canyon...___-------______._

14

Rock

Creek..

21,24,25,42

moraine..______________....-

27

Rocks,

andesitic._.-__.____-. ...

13

basement.-.__...

..

12,22,24,27,41

clastic.

12,13

Cretaceous...____ .

13,14

Lower_____..__.. -

-

12

middle...

12

Upper......-.-_ ...

13

Eocene,

middle..._______.-.. ...

14

granitic...

12,13,14

intrusive..._____.. .

12

Mesozoic._._____...

.

12,14

metamorphic-___

12

Paleozoic-

-

12,14

Precambrian..._... .

12,14

pyroclastic--

_-

13

sedimentary...-_..

12,14

Tertiary

12,

IS

lower.__________

13

middle....-- -

13

volcanic_______________ __

12,

IS

Rocky

Mountains-________

21

Runoff.

41,42

snowmelt...________..

42

Scarp....._______________. ...

27

erosion...__.___._______.._

24

faultllne

24

Sedimentary

deposits...______._.__

IS

Tertiary

.

13

Sedimentary

rocks_._____..._..

12,14

Sediments,

Miocene...__.__.___

13

Miocene,

lower....____________

16

Oligocene...__....___..______

25

Pliocene..__.___________

17

middle..-

16

Sediments,

Miocene Continued

Page

Quaternary______....._____..

46

Tertiary

13,22,36,37,41,46

44

Seismic

data...________________

25

Settling

ponds.__________________

43,44

Sheep

Rock.._________________

20

Silver

Bow

County..._____________

7

Slope

wash__________________

22,26,37

Slumping....___________________

25

Smelter,

near Warm

Springs

Creek..

_.

__

11

Washoe - .- ...... ......__.

24,44

Soil-moisture

storage....._______.__

44

Specific

capacity.... _.________

8^,36,37

defined-

-...._..__...____

30

Spring

Gulch.

_. ...._...

12,15,25

Springs.. ------- .......__.. ...

44

thermal ......_.__.._. ...

11,44

Stockuse ----__

36,37,47

Storage.---

------_ .. ..

39,41

coefficient

of,

defined-

__________

30

Strata,

Pliocene..______.________

25

Pliocene,

middle.....___._______

27

Tertiary...

...

.

13,14,15,27

lower._________________

25

middle..

25

Stratigraphy,

intravalley.

__________

IS

regional.----.-----._._____.._

It

Streams,

effluent... _ .. .

42,43,44

influent....______._________

42

Structure,

domal_____._____.___

24

intravalley...____..___..__._

14

regional.....__._..._..__... ..

84

Surface-water

rights..____._.____...

46

Swamps._____________________

44

Synclines.._________.________

24

T

Tailings

water.. ..... -

..

44

Tectonic

activity,

intermittent __

.

27

Temperature,

highest-.. -

-.---.---_

..

9

lowest..-_.__._ _ .

9

monthly..-..-.---------.---------- -

9

Terminal

moraines ._______-....

21

Terraces -

7,11,13,20,21,22,25,36

alluvium..._..__--.____._-----

36

Tertiary,

age.

._.. ..__

13,35,47

aquifers...

.- .__.. ._ .

36

beds

38

deposits...__- .-- . -

IS

early,

age..-._____._...- .

12

history.___-___

.

85

late,

age.-----.---__.....

15

lower,

beds_________.__._

17,24

rocks. .-

...

13

strata

25

middle,

age

12,15

beds

17,24

rocks..

.

...

13

strata...- -

25

rocks-- .

12,

IS

sediments-.-... ------

13,22,36,37,41,46,47

transmissibility,

coefficient

of...

32

strata-.--

13,14,15,27

Test

holes

46

INDEX

55

Page

Tests,

aquifer

32,34,38

multiple-well_______________

32

single-well..---..-.---.---..._._......

34

Thermal

springs.

- ._------

11,44

Thiessen

polygons._________.____

41

Thunderbolt

Mountains..... _______

7

Tile

drainage

system.....__________

43

Time,

Eecent....._-.._....._....---...

27

Wisconsin_________________

27

Tincup

Joe

Creek__

_____________

21

moraine.__________________

27

Topography__________________

7

Trains,

boulder

20,27

gravel ________ _______

20

outwash.__________________

27

Transmissibility,

coefficient

of- -

34,36,37,38

coefficient

of,

denned-__________

31

Quaternary

alluvium.-._______

32

Tertiary

sediments.________

32

Transpiration.._____.__________

43

Travertine...________________.

24

Tri-City

gravel

pit-.

22

Tuff..._--------..---.--------.--.-.----..--

14,26

siliceous.__________________

13

welded .

12,15,22,24

Unconfined

water-

Underflow..___.

Vertebrate,

fauna___________..

16

Volcanic

ash..____...___

19,26

Volcanic

rocks.......--.._..---....-----.

12,JS,26

W

Warm

Springs... _..-.-..-..---..

9,11,44

Warm

Springs

Canyon____________

22,25

Page

Warm

Springs

Creek .

9,

12,14,21,23,27,36,38,41,42,43,44,46

fans--.- . . -

22,24,46,47

Wash,

slope.._________________

26

Washoe

Smelter___-____-__...

24,44

Water-level

fluctuations____________

S9

long

term___....___...__

39

seasonal..--___________---.

39

Water

table... ..... .

31,37,39

denned.- ._..

... -.- -..

31

Water-table

aquifer,

defined.._____-----

31

Water

use,

domestic

36,37,46,47

industrial

36,42,47

irrigation

11,36,41,42,46,47

municipal..__________-__.-..

46

stock.

36,37,47

Well-numbering

system..____.._._...

6

Wells,

artesian..._________._

._

41

depth

in

valley______________

31

domestic..._______-_____-..

46,47

dug

36,37

gravel-packed...-__.___.__.. ..

46

industrial..._._____

____-..

46

irrigation..._--------------__ .-

46

municipal..__.. __ _..-

46

Deer

Lodge. ----------------------

37

State

institution.______.__.

___

46

stock--..----...--------------.---------.-

46,47

Willow

Creek-... . -

16,38,43

flat. - .

22

Wisconsin,

early,

age. ___.--__ -..

21

moraines-___.____________

8,22,27

terminal.._-------------------------

21

Woodard

Gulch....._-

..-

17

Zone

of

aeration,

defined....______

.

31

Zone

of

saturation,

defined..

____.- -.

31

U.S.

GOVERNMENT

PRINTING

OFFICE:

1968

O 293-420