jfa(2005) assigning context to artifacts in burned-rock middens_leach et al.pdf

7/26/2019 JFA(2005) assigning context to artifacts in burned-rock middens_Leach et al.pdf

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Assigning Context to Artifacts in Burned-Rock Middens

Author(s): Jeff D. Leach, C. Britt Bousman, David L. NickelsSource: Journal of Field Archaeology, Vol. 30, No. 2 (Summer, 2005), pp. 201-203Published by: Boston UniversityStable URL: http://www.jstor.org/stable/40024943

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Assigning

Context to

Artifacts

in

Burned-Rock Middens

JEFF

D. LEACH

University

of Leicester

Leicester,

England

C.

BRITT BOUSMAN

DAVID

L.

NICKELS

Texas

State

University-San

Marcos

San

Marcos,

Texas

Accumulations

of ire-

crocked rock and carbon-stained sediment in

pits

mark locations

of past cooking

and

heating facilities

around the

world. While the

specific unctions of

these

features may vary,

the use

of

stones as

heating

elements

in

earth ovens is common.

After

repeated

use,

debris in the

form of ire-

cracked

stones, charcoal,

ash, sediment,

carbonized

plant fragments,

and other

materials accumulates to

form

low mounds known in

the

U.S. Southern Plains and the Southwestas

burned-rockmiddens. The middens

may

include

artifacts,

some intro-

duced

inadvertently

with

sediment used to

form

an earthen

cap

to seal

the

pit

oven.

The sediment

and included

artifacts for

this

insulating

cap may

be

borrowed

from

other

parts of

the

site.

After

the

cooking

is

complete,

the earthen

cap

is

peeled open

and all materials

redistrib-

uted

by trampling

and

slope

wash.

Artifacts

and other

materials in

burned-rock

middens,

therefore, may

not

represent

discrete

events

or

periods

directly

associated

with

use

of

the

ovens.

201

News

and

Short Contributions

Introduction

Large

accumulations of fire-cracked rock known as

burned-rock

middens dot the

landscape

in Central Texas

(Black

1997).

These features

appear

as

amorphous

masses

of fire-cracked

rock

and carbon-stained sediment

lacking

visible

structure.When

excavated,

however,

rock-lined

pits

and

intact central

oven features surrounded

by

an amor-

phous

secondary

accumulation

of

burned

rock

and

other

materialsare revealed

(Black1997).

Many

of these

mounds

reach several

meters in

height

and as much as 20 to 30

m

in

diameter

as the result

of

repeated

use as

oven

facilities

for extended

periods

of time.

Material recovered from burned rock middens includes

chipped

stones,

ground

stone

tools,

mammal

and

reptile

bones,

floral

remains, snails,

mussel

shells, ornaments,

burials, ceramics,

and other items.

Archaeologists

often re-

ly

on artifacts

and other materials recovered from these

middens to answer research

questions.

Unfortunately,

arti-

facts

recovered

from

middens

may

not be in

situ,

in

the

sense of

being part

of the

activity

at the

midden,

but were

introduced to the

midden with sediment

borrowed from

other

parts

of the

site. This sediment formed a

cap

that

sealed the centraloven

feature.When the oven

was

opened,

the

earth

cap

and

any

artifacts t

might

contain

were

spread

away

from

the

pit

oven.

Repeated

use further

inadvertent-

ly

jumbled

the

intrusive artifacts

with the oven

deposits.

Ethnographic Examples

of

Burned-Rock

Midden Formation

No direct observations of

people

in

CentralTexas

using

earth

ovens

exist,

but

accounts

of

cooking

in

pits

using

rock

heating

elements are

available from

the American

Southwest and northern

Mexico. For

example,

Castetter,

Bell,

and

Grove

(1938: 28-29)

describe

cooking agave

in

pits

among

the Mescalero and

Chiricahua

Apache:

Pits in which the crownswerebakedwere about ten to

twelve eet

in

diameter nd threeor

four feet

deep,

ined

with

large

flat rocks...

Upon

this,

oak and

juniper

wood

was

placed,

andbefore he sun came

up

was set on fire.

By

noon the

firehad died

down,

and on these

hot stoneswas

laid moist

grass,

uch as bunch

grass...

The

largest

mescal

crownwas selected.

they

threw t

in

and threw he other

crowns

after

t... Afterthe mescalhad been

coveredwith

the

long

leaves

of bear

grass

andthe whole with earth o a

depth

sufficient o

prevent

team rom

escaping.

This account illustrates he basic

steps

for

cooking

in

an

earth oven. These include

digging

a

pit, adding

stones and


3/4

202 News

and

Short

Contributions

Figure

1. In this

badly

backlit

1906

photograph

an

Apache

woman and children are

sealing

an

agave

oven

with

soil. The two children in the

background appear

o have collected soil from some distance

from the

oven. This

photograph

by

Edward S. Curtis

is

reproduced through

the

courtesy

of Northwestern

Uni-

versity Library.

fuel,

and

setting

it

on fire

(Bell

and Castetter

1941;

Boas

1930;

Chestnut

1902).

Once the fire has burned down

and

the stones are

sufficiently

heated,

a

layer

of

vegetation

is

used to

protect

the food from the hot rocks. The

plant lay-

er also

provides

moisture

during

the

cooking process.

The

food to be cooked is

arranged

on the

plant layer,

and a

sec-

ond

plant layer

is

placed

on

top

of the food to serve

as a

thermal barrier.

Finally,

earth is used to seal the feature

(fig. i).

Once the food is

cooked,

the oven is

dismantled,

the

food

removed,

and the

process

is

repeated.

Earth Oven

Experiments

The earthen

cap

is the last critical

step

in the construc-

tion of the oven and is intended

to

serve

as a thermal seal

allowing

the

food

to cook. The amount of earth

required

to

properly

seal an

oven

is not well documented

in the

ethnographic

literature.

Experiments

(Leach

et al.

1998),

however,

suggest

that a

moderate

size

oven,

just

a meter in

diameter,

requires

almost half a cubic meter

of material

(490

kg

of

sandy

loam)

to

adequately

seal the oven.

The

process

of

borrowing

earth to cover ovens has

important

implications

for the

understanding

of formation

processes.

If earth

was

regularly

used

to

cap

ovens,

it is

possible

that

the collection

of earth would have

incorporated

artifacts

from

elsewhere on the site that are unrelated to the oven.

If the

charred and

fragmented

stone in a midden is the

residue

from numerous

firings,

many

earthen

caps may

have

been constructed

to cover

the

feature. In the

experi-

mental oven

(Leach

et

al.

1998),

it was

necessary

to bor-

row earthto seal the oven

properly

for its firstuse; the soil

excavated

o create

the

pit

was not

enough

by

itself.

In sub-

sequent

firings,

it

was

possible

to reuse

earth but

each

time

an

earthen

cap

was

dismantled

the earth was

widely

scat-

tered.

The soil

is

dispersed

over

time as the result

of sheet

wash. With

each additional

use of

the

oven,

freshsediment

is needed.

As a

consequence,

there

is a

cycle

of earth

mov-

ing

and

subsequent

dispersal

that

may

result

in the unin-

tentional

transport

of artifacts rom

other

parts

of the

site

to the

area of the

oven.

Discussion

We do not

suggest

that

all artifacts

or

ecofacts

recovered

from these middens are derived from earth or sediments

excavated

on the

sites.

Determining

which

materials

have

been

introduced

by

the

process

of

transporting

borrowed

sediments,

and

which

materials

are

properly

part

of the

fea-

ture and

inform us

about

its

use,

remains

an essential

goal.

As

a

start,

we assumethat

the artifactual

ontent

of burned-

rock middens will

almost

always

reflect both

everyday

ac-

tivities

associated with

the use

of the

oven,

and activities

that have

very

little

to

do

with

preparing

or

cooking

foods

in earth.


4/4

Journal

of

Field

Archaeology

Vol.30,

2005

203

During

the use-life

of an oven

the discarded

material

around

it

will

be

trampled,

scattered,

and disturbed

during

subsequent

firings.As this deposit accumulates, ts uncon-

solidated

and

poorly

sorted structure

s

subject

to

erosion,

which

may

remove

the

smaller

fractions of

sediment,

arti-

facts,

and stones.

As the

midden

deposit

thickens,

it

will

constitute

a

stratigraphic

unit with

a

complicated

history

of

formation.

It will record

the

depositional

history

of the

oven,

but

it

will

also record artifact

mixing

through

bor-

rowed

sediment,

possibly

reversed

stratigraphy,

and

cer-

tainly

a mixture

of different

components

from the

site,

if

multiple

components

exist.

Conclusions

It

is

important

to

appreciate

hat burned-rock middens

may

often, if not

always,

contain unrelated artifacts

brought

in from elsewhere

on the

site as the result

of

the

construction

of

caps using

borrowed

earth.The earth

s ob-

tained

from

portions

of the site we call the borrow

zone.

If earlier

components

exist

at sites

with

burned-rock mid-

dens,

artifacts

may

be

incorporated

n

the midden. Thus ar-

tifacts

recovered from the

midden,

including

radiocarbon

assays

from carbonized

plant

remains,

could

produce

mis-

leading

results,

especially

f the associated artifactsare

used

to date

the

midden.

The re-use of earth from

earlier com-

ponents

to cover earth ovens could result in

yet

another

problem, namely

artifacts hat are

functionally

unrelated

to

these ovens.

A

complete

understanding

of

these features

is

not

possible

until the formation

processes

relatedto them

have

been

examined

in

detail.

JeffD.

Leach s a Ph.D. candidateat

Leicester

University,

United

Kingdom.Mailing

address:

chool

of

Archaeology

nd

Ancient

History,University f

Leicester,

University

Road,

Leicester EI

7RH,

United

Kingdom.

E-mail:

jejf@cookstonetechnology.

om

C. Britt Bousman s assistant

professor f

Anthropology

nd

Director

of

the

Center

for Archaeological

tudies

at

Texas

State

University-San

Marcos.

David L. Nickels s a researchcientist t the Centerfor

Archaeological

tudiesat TexasState

University-San

Marcos.

Bell,

W.

H.,

and EdwardE

Castetter

1941

Ethnobiological

tudies n theAmerican

Southwest,

II.

The

Utilization

of

Yucca,

otol nd

Beargrass y

the

Aborigines

n

theAmericanSouthwest. ulletin 372.

Albuquerque:

Uni-

versity

of

New

Mexico.

Black,

Stephen

L.

1997 Scenarios

f Midden

Accumulation,

n

Stephen

L.

Black,

LindaW.

Ellis,

Darrell

G.

Creel,

and Glenn

T.

Goode, eds.,

Hot Rock

Cooking

on the Greater

Edwards

Plateau: Four

BurnedRockMidden Sites n West

Central

Texas.

tudies n

Archeology

2. Austin:Texas

Archeological

ResearchLabo-

ratory,

The

University

of Texasat

Austin,

140-150.

Boas,

Franz

1930

The SalishanTribes

of

the Western

Plateaus,

n

James

A.

Teit, ed.,

The

Forty-fifth

nnual

Report

of

the Bureau

of

American

Ethnology

927-1928.

Washington,

D.C.: Smith-

sonian

Institution,

23-396.

Castetter,

Edward

E,

W H.

Bell,

and

A.

R. Grove

1938

The

Early

Utilization

and the Distribution

of Agave

in the

American

Southwest.

niversity f

New

Mexico

Bulletin,

Bio-

logical

Series

Vol.

5,

No.

4.

Albuquerque:

The

University

of

New

Mexico.

Chestnut,

V

K.

1902

Plants

Used

by

the

Indians

of

Mendocino

County,

Cali-

fornia,

Contributions

from

the US. NationalHerbarium

7:

294-408.

Leach,JefFD.,

David

Nickels,

BruceK.

Moses,

and RichardJones

1998

ABrief

Comment

on

Estimating

Rates of

Burned Rock

Discard: Results from an

Experimental

Earth

Oven,

La

Tierra

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