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University of WollongongResearch Online
Faculty of Science, Medicine and Health - Papers Faculty of Science, Medicine and Health
2012
Usewear and phytoliths on bedrock grindingpatches, Pilbara, north-western AustraliaRichard FullagarUniversity of Wollongong, [email protected]
Lynley A. WallisUniversity of Queensland
Research Online is the open access institutional repository for the University of Wollongong. For further information contact the UOW Library:[email protected]
Publication DetailsFullagar, R. & Wallis, L. A. (2012). Usewear and phytoliths on bedrock grinding patches, Pilbara, north-western Australia. Artefact:Pacific rim archaeology, 35 75-87.
Usewear and phytoliths on bedrock grinding patches, Pilbara, north-western Australia
AbstractBedrock grinding patches were recorded in the Fortescue Metals Group Ltd (FMG) Rail Corridor within theWooodstock/Abydos Aboriginal Heritage Area 130 km south of Port Hedland, Western Australia. WA StateMinisterial conditions required the salvage of representative samples, residue analysis and other detailedmicroscopic study to investigate the technology and function of these grinding patches. Following a pilotstudy and experimental work, we undertook microscopic study of 159 samples - including PVS (PolyVinylSiloxane™) peels and water extractions - from 81 grinding patches, collected at six sites. The worn stonesurfaces are microscopically similar to traces found on experimental and Aboriginal stone artefacts used forgrinding seeds, although the development of wear patterns is variable. The most common residues werephytoliths, which indicate that grinding patches were utilised for grinding grasses of the Panicoid andChloridoid sub-families, although the open nature of the sites means issues of taphonomy need to beconsidered. Spinifex phytoliths suggest seeds from this plant may also have been exploited. No traces ofpigment or ochre were found. We suggest that the grinding patches are linked with food processing associatedceremonial gatherings and rock art.
DisciplinesMedicine and Health Sciences | Social and Behavioral Sciences
Publication DetailsFullagar, R. & Wallis, L. A. (2012). Usewear and phytoliths on bedrock grinding patches, Pilbara, north-western Australia. Artefact: Pacific rim archaeology, 35 75-87.
This journal article is available at Research Online: http://ro.uow.edu.au/smhpapers/2681
1
Usewearandphytolithsonbedrockgrindingpatches,Pilbara,
north‐westernAustralia
RichardFullagar,UniversityofWollongongandScarpArchaeology
and
LynleyWallis,FlindersUniversityandWallisHeritageConsulting
Abstract
Bedrock grinding patches were recorded in the Fortescue Metals Group Ltd RailCorridorwithintheWooodstock/AbydosAboriginalHeritageArea130kmsouthofPortHedland, Western Australia. WA State Ministerial conditions required the salvage ofrepresentative samples, residue analysis and other detailed microscopic study toinvestigatethetechnologyandfunctionofgrindingpatchesinthearea.Followingapilotstudy and experimental work, we undertook microscopic study of 159 samples –including PVS (PolyVinyl Siloxane™) peels and water extractions – from 81 grindingpatches, collected at six recorded sites. The worn stone surfaces are similarmicroscopicallytotracesfoundonexperimentalandAboriginalstoneartefactsusedforgrinding seeds, although the development of wear patterns is variable. The mostcommonresidueswerephytolithswhichindicatethatgrindingpatcheswereutilisedforgrindinggrassesofthePanicoidandChloridoidsub‐families,althoughtheopennatureof the sites means issues of taphonomy need to be considered. Spinifex phytolithssuggest seeds from this plantmay also have been exploited. No traces of pigment orochrewerefound.Wesuggestthatthegrindingpatchesarelinkedwithfoodprocessingassociatedceremonialgatheringsandrockart.
Introduction
As part of a heritage mitigation strategy, Shaun Canning, ACHM (Australian CulturalHeritage Management) and Gavin Jackson (Gavin Jackson P/L) invited RF to salvagesome granite grinding patches in the Pilbara, Western Australia (WA). WA StateMinisterialconditionsrequiredthesalvageofrepresentativesamples,residueanalysisandotherdetailedmicroscopicstudytoinvestigatethetechnologyandfunctionofthegrinding patches prior to their destruction. The bedrock grinding patches had beenpreviously recorded in the FMG Rail Corridor within the Wooodstock/AbydosAboriginalHeritageArea130kmsouthofPortHedland,WA(Jackson2006).Theareais
60‐200subseqevaluatfieldwoon KarKarriyato samrecordiall worunwornresidueGavinJPVSanthis pamicrosgrindinethno‐h
StudyA
Thestusouthessenti(BoM2
Figure
0 km southquently invte possibilorkwithRFrriyarra coarracommple14griningandsamrn grindingn surfaces.es from thJacksonresndaqueousaper,we oucopic studngseeds,inhistoricale
Area
udyareaisof Port Heially a ston2012).The
1:Studyar
h of Portvited Alanlities for dF,AlanWaountry inunitymemndingpatchmplingmeg patches. An aqueohe abundansultedinthresiduesautline the rdy, suggestncludingpeevidence.
partofbotedland, inny desertwvegetation
rea.[Sourc
Hedland iWatchmandating orgatchman,GDecember
mbers(Bruches from fthodology.(from theous samplent cracks iheapplicatamplesfromrecordingmting that therhapsthet
thKarriyarthe Pilba
with irreguisdominat
ce:FMG]
in Karriyan to underganic accreGavin Jacks2006 in
ceBungandfourAborig.Polyvinylsmootheste was alsoin the grantionofthismsixmoremethodolohe grindintinyseeds
rraandPalyara regionular and vetedbyacac
arra and Prtake geoloetions ononandBoothe compadAndrewGginal sitesSiloxane(t looking sremovednite surfacmethodoloesites(n=8gy and sumng patchesofspinifex
ykucountrof WA (F
ery low raiciaandspin
Palyku Aboogical invethe grindioneLaw(Aany of FMGordon).Ainorder toPVS)peelssurfaces) ausing a pie. Subsequogytoreco81grindingmmarise kwere mos,forwhich
ry,approximFigure 1).nfall, 150‐nifexscrub
original lanestigationsing patcheACHM) tooMG personnkeyobjectodevelopasweretakeand from apette to suuent fieldwoverafurthgpatchestokey findingst likely uhthereison
mately60‐The lands300mmp(Figure2)
2
nds. RFand toes. Thisokplacenel andtivewasaviableen fromadjacentuck anywork byher159otal).Ins of theused fornlyrare
200kmscape isper year.
3
Figure2:Spinifexandacaciaspeciesdominatethelandscapearoundthegranitedomesandgrindingpatches.[Photo:BooneLaw]
Watchman(2007:4)inhisgeologicalreportnotedthatthestudyareagenerallylies
‘between the Pilbara hinterland of iron‐rich sediments and the coast, and essentiallycompriseslowgranitehillsabout200minelevation.VariousArchaeangraniticrockscropoutintheareaandthesecomprisetheYuleBatholith(HickmanandLipple1978).’
Watchman (2007:4) described one typical sitewith unusual xenoliths (rocks that areenvelopedinalargerrockduringformation):
‘AtsiteKAR06‐02thisstructuraldomeofgranitoidsispartofamigmatitesuiteofrocksconsistingof fine tocoarse‐grainedequigranular toporphyriticbiotiteadamelliteandbiotite granodiorite. Leucosomes of thin aplite dykes and pegmatites have intrudedparalleltothefoliation.
At site KAR 06‐02 a narrow, even‐grained aplite has intruded the porphyritic biotiteadamellite,anditisonthisequigranularintrusiverockthatthegrindingpatch(#1)wasmade (Figure 3). The aplite dyke is approximately 55cm wide and contains pale,elongate xenoliths (near the colour scale in Figure 3). The dyke trends at 30° andalthoughgenerallyflatontophasaslightdipofapproximately10°tothenorthwest.’
Thegraniteincludesquartzthatvariesingrainsizeandisveryhard. Hundredsifnotthousands of grinding patches occur in this area and their function is thought to beeitherforpigmentpreparationorgrindingplantfoods(Jackson2006).
BedrockGrindingPatches
The granite commonly outcrops in the form of domes rising gently above the sandyplain.HundredsofgranitegrindingpatcheswererecordedbyACHMandGavinJacksoninanareawheretheFMGrailwasproposed(Jackson2006).Thesampledpatcheshavemacroscopicsmoothingvaryingfromabout30cmx15cminmaximumdimensionsup
4
toabout300cmx150cm.Grindingpatchmorphologymostlyfollowstheflattoslightlyconvextopographyofthegranitedomes.Somegrindingpatcheshavedepressionswornfrom use, forming a concave cross‐section. Some grinding patches are adjacent tostreambeds or natural shallowdepressions in the granite that have heldwater afterrain (Figure3 andFigure4), thoughothers are associatedwithno obvious source ofwater.
Thegranitegrindingpatchesinthestudyareaexhibitdifferentdegreesofgrindingandsome variation in the type of granite on which they occur. Some surfaces are veryweathered, andmodification by grinding shows up very clearly. Other granites haveexfoliatedandexposedrelativelyfreshsurfaces,someofwhichhavealsobeenusedforgrinding.
Figure3: Somegrindingpatches (on theedgeof thegranite slab,below thepinkandblackflaggingtape)haveshallowdepressionsandarelocatednearstreambeds.[Photo:BooneLaw]
Figure4:Somegrindingpatchesareonlowdomesofgranitebutstreambedsarelessthan a few hundred metres away. Left to right: Gavin Jackson, Bruce Bung, Andrew
5
Gordon,AlanWatchman,withRFcrouchingandpointingatthegrindingpatch.[Photo:Boonelaw]
Occasionally upper grinding stones or hand stones were found near the grindingpatches.Handstonesaretypicallymadeofaharddolerite(Figure5).
Figure 5: An upper grinding stone or hand stone (dolerite) found near a bedrockgrindingpatch.[Photo:BooneLaw]
Althoughweareawareoffewtool‐useexperimentsundertakenspecificallyongranite(butseebelow),manytool‐useexperimentshavebeenundertakenutilisingquartz,andit is the smoothing, polish, and striations on quartz‐rich rocks that provide a key forinterpretingtheusewearpatternsdescribedbelow(e.g.Fullagar1991,2006).
Karriyarra community members Andrew Gordon and Bruce Bung involved with thefieldwork project suggested that grinding patchesmight have been used for grindingochre for body paint. Consequently, the grinding patches are thought to be linked tobody painting and men’s ceremonies performed near adjacent Aboriginal rockengravings on dolerite outcrops, similar to the granophyre rock formations on theBurrup.
ExperimentalArchaeology
Twotool‐useexperimentswereundertakenbyRFinthefield.SpinifexandAcaciaseedswere harvested and were ground to flour in a period of about 30 minutes, using adoleritehandstoneandagraniteslab(Figure6).ThemainpurposeofthisexperimentwastoenableRFtoobservethenatureofgrindingusewearongranite.Itislikelythatthemainformofabrasivewearisaconsequenceofgrindinghardstonestogether(asitisforsandstoneseedgrindingimplements).However,thepresenceofsiliceousparticles(phytoliths) and other plant tissue also contributes to polish formation, as has beendocumentedforawiderangeofprocessedmaterialsinnumeroustool‐useexperiments(e.g.Hamon2008).
6
Grindingexperimentswerealsoundertakenwithredochre(hematite)which leavesadistinctive, bright, extremely fine‐grained residue that was extremely difficult toremove.Inthisinstancethegrindingprocessrapidlyceasedtobeeffectivebecausetheochre firmly filled all the depressions and cracks, creating a hard smooth film andcloggingthehardsharpgrainsoftheoriginalroughgranitesurface.Becausethestonesweretoolargetofitonamicroscopestage,polyvinylsiloxane(PVS)peels(seebelow)weretakentofacilitatethestudyofthegrindingsurfacesathighmagnificationusingalightmicroscope.
Polishdevelopmentunderthesegrindingconditionsprobablycannotextendbeyondastagewhen grains are plucked from the surface (see Figure 7). These plucked grainsprovide free abrasives that will constrain the extent of polish forming as the entiresurface is gradually worn down (Kamminga 1979). More compacted, homogenousstones(suchasquartzite)cansustainmuchmoredevelopedpatchesofpolish,butthesurfaceofthegranitefromthisstudyareaisconstantlyandrapidly
Figure 6: Experimental grinding tools used to grind Spinifex and Acacia seeds. Left:lowergrindingstone(granite).Right:Handstone(dolerite).Scalebarisincentimetres.[Photo:RF]
Polishdevelopmentunderthesegrindingconditionsprobablycannotextendbeyondastagewhengrainsarepluckedfromthesurface(seeFigure7).
FigureLeft: sobeenpgrindinScale:D
beingwgrindin
Method
Weusepatchescleanedresidue1998),adjacenreplicatunderadisposawhereagitatewaterremoveexaminvisiblemicros
Inaddiremovesurfaceweren
7:UseweaomebroadluckedfromngstoneshDiagonalis
wornwithngtoolscom
dology:sam
edtwotechs. First, thd by wipines.Then,awasusedtnt area witedwithexametallograblenylonthe PVS sadwiththeand any red with thnation reveintheserecopeatx20
tiontotheed by Alanes microscootvisibleo
aronexperd striationsmthesurfahowingfineabout1mm
use, in themmonlyfou
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peelsandn Watchmeopically; thonthegrind
rimental loand abras
face.Scaleoestriations,m.[Photo:R
esamewayundinothe
dingpatch
gathersam be samplrfaces vigopressioncoighresolutnding (Figaritysuchectedlightmodeliverpere taken oandlefttohad ‘suckand transawide ranpleswhen
residuesamen so thathis was codingpatche
owergranitsive smootonleft is in,smoothinRF]
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mplesforstued (thoseorously wompound,ptionimpresgure 8). Usthatnaturmicroscopepurifiedwaon the grinsoakintoked up’ frosferred tonge of partviewedmi
mples,tinyt I could eonsidered nesatlowm
tegrindingthing. Notenmillimetrgandpolis
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udyingthedeemed to
with ethanopolyvinylsissionofthesing this mal fractureeatx200matertothepnding patchcracksintom the crsealed nylticles includicroscopica
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apidlythanalia.
esidues
functionofo be the ‘mol to remoiloxane(PVegrindingmethod qufeaturesw
magnificatioporousroch (Figure 9thegraniteacks andon tubes (ding phytoallyundera
mthegrindhe polishedbecause usoninthefie
hown inFigwhere grainPVSpeelocoloureds
n)sandsto
fbedrockgmost wornove looseVS)(seeMasurfaceanuartz grainwereeasilyon.Nextwecksurface9). Thewaforaminurock surfa(Figure 10olithswereatransmitt
dingsurfacd and unpse‐wear steld.
7
gure6).ns haveof lowertreaks).
neseed
grindingn’) weresurfaceandikosdofthens wereyvisibleeusedaclosetoterwasute.Theace was). Latere clearlytedlight
eswerepolishedriations
8
Figure8:RFdeliveringPVS(withmixingdispenser)tothegrindingpatchsurfaceKAR06‐21GP16.[Photo:BooneLaw]
Figure9:RFtakingaresiduesamplewiththedisposablenylondropper.[Photo:BooneLaw]
Figure10:PVS (greenpeels)andresidue (sealed tube) samplesonandoffagrindingpatch.Theredstainisformedbyveryfinesedimentatthemarginofdepressionsthatfillwithrain.ThegreenPVSpeelswereremovedandsealedinplasticbags.LargerPVS
peels ([Photo:
Results
Usingastriatiofrom gprovidepeelsothisme
FigureWidth1mm.[
FigurePVSSamThephabout2
(the size of:BooneLaw
s:Use‐wear
astereoscoonswere nrinding paedanegationfreshlyfethod(Figu
11:Striatioof field ab[Photo:RF]
12:Impresmple11tahotowasta2mm.[Pho
f standardw]
robservati
picmicrosnoted to beatches (Figuiveimpresfracturedqure12).
onsvisibleout 1cm.R
ssionoffreakenawayfakenatx10oto:RF]
microscop
ons
copeinthee very comure 11). Adsionbutwuartzgrain
onrocksaRight:Deta
eshfracturfromthem00magnific
pe slides)w
elaboratorymmon on thdditionallywithsufficiensindicate
amplefromail of usew
resandstremostwornacation,and
weremade
y,withlowhe small flay, the PVS pentdetailtotheexcelle
mgrindingpwear on roc
esslinesonareaatgrinthemaxim
e for some
wangledpoaked rockpeels fromoseethesentresolut
patchKAR0ck sample.
naquartzndingpatchmumdimen
grinding p
ointsourcesamples re
m grindingamefeaturtionachiev
06211A(Diagonal i
grain(circhKAR062nsion(diag
9
patches.
oflight,emovedpatchesres.PVSablevia
4).Left:is about
cled)on1GP38.gonal)is
Athighfrom gLowpowithhaflatwit
ThePVareflecofpolisothers.
FigureGP16.bottomRight:KRF]
hermagnifigrinding paoints on thardgrainsothfewerstr
VSimpressictedlightmshandstria
13:PVSpeNotefines
m left. LighKAR0601
icationundatches showhepeel (i.eofquartzthriations(Fi
ionsfromemicroscopeationswer
eelsfromsmstriations(shter patcheGP1Samp
derametalw abundan. highpoinhathavemgure13an
eachgrindie.Twokindrecommon
moothpolisslightlydares with smple2.Scale
llographicnt fine strints on themoresmootndFigure1
ngpatchandsofsmootnonsomeg
shedsurfacrkerscratcmall depreseforbothim
(reflectediations indgrinding stthinganda4).
ndoff‐sitethingorpogrindingpa
ceofgrindiches)andassions (damages:dia
light)micrdicating abrtone surfacappeartoh
controlswolishwerenatchesand
ingpatcheslignmentsrker patchgonalisab
roscope,PVrasive smoce) are asshavebeenp
werestudienoted.Aligrareorab
s.Left:KARrunningtohes) are pbout1mm.
10
VSpeelsoothing.sociatedpolished
dundergnmentsbsenton
R06‐21opright‐olished.[Photo:
11
Figure 14: PVS peels from grinding patches. Left: PVS peel from KAR 06 19 GP 1,showingexceptionallywelldevelopedpolishonhighpoints(lighterareas)withdarkerpatches indicatingdepressionsonthestone itself.Right:PVSpeel fromPALVII0602GP35showingmuchmoreabrasiveconditionswithstriationsoriented inat least twodirections.Scaleforbothimages:diagonalisabout1mm.[Photo:RF]
Nevertheless some surfaceswere highly smoothed and flat; and had sustained brightpolishwhich is presumably a consequenceof the stone types and thematerialwhichwasbeingground.
Results:Phytolithsinresidues
Atotalof97residuesamplesfrom95grindingpatchesat10siteswerestudiedbyLW.Thesesampleswereanalysedbyexaminationof themountedresidueonaglassslideusinga transmitted lightmicroscope.This revealed that theaqueous residuesamplestypicallyhadabundantresiduespresent,includingphytolithsandstarchgrains(Figure15). Phytolithswererecordedasbelongingtooneof23 ‘distinctive’(ierecognisable)categories:sinuousedgedrod,straightedgedrod,spinyedgedrod,blockyquadrilateral,haircellovoid,trichome,elongatedhaircell,unilobe,bilobewithalimitedwaist,bilobewith a defined waist, spheroid [which typically indicate the presence of spinifexgrasses], angular quadrilateral, Eriachne [bilobe on a base], Aristida [bilobe with adistinctive long shaft], polylobate, sphere, quadrilateral plate, sinuous edged plate,bulliform, Acacia [irregular amorphous form with surface ornamentation], stomata,Cyperaceae[platewithdistinctivepatternednodes]and‘others’.Additionally,piecesofamorphous plate and amorphous fragments of thicker, irregularly shaped, non‐repetitivemorphologieswerealsonoted;theselattercategorieswereexcludedfromthetotal phytolith countsusedboth to compare the relativephytolith abundance in eachsampleandtoconstructthephytolithdiagrams.
Figure 15: Left: Residue extraction from KAR 06 10 GP1 Sample 3, with phytoliths(somewithserrateedges)Scale:diagonalisabout1mm.Right:Starchgrain(diameter18microns – too large to be from grass) fromKAR06 01GP1. Cross polarised light.[Photo:RF]
AnalysiabundaresultophytoliSpinifeproducsub‐fam
FigureAcacia,bottomare20
Althougofgrindsupporutilisedphytoliwas simfamilie
isconfirmeance of phyoftaphonoith types oxgrasses(cedbyavamilies.Sixo
16: Somesecondro
m row: Spinmicrons,B
ghitisnotdingowingrt forthepd for the gith analysismilar in eas.
edtheubiqytoliths prmicfactorsobserved i(Figure16)arietyofgrofthesites
of the phyowdown:Pnifex (alsolackbarsa
tpossibletg to theoppropositiongrinding os suggestsach case, b
quitouspreesent in easratherthancluded th),andassemasses,partarediscuss
ytolith typePanicoideaein the Chlare5micro
tobeentirepennature that inallof plant mathat the p
being typica
esenceofpach sampleandifferenhose frommblageswticularlymsedhere(F
es observedegrasses,tloridoideaens.[Photo:
elycertainof thesitelcasestheaterials, asplantmaterally grasse
phytolithsie varied concesinorigAcacia, an
weredominembersofFigure17).
d in this stthirdrowde subfamilyLW]
thatallofessampled,sampledgs opposedrial proceses of the P
nallsamplonsiderablyginalusepand PanicoidatedbymotheChlorid
tudy. SEMdown:chloy). Scale:W
theresidue,phytolithgrindingpato ochresed on theanicoid an
lesexaminy,most likeatterns.Diad, ChloridoorphologicadoidandP
images. ToridoideaegWhite strip
eswerethanalysispatchfeaturepreparatio
e grindingnd Chlorido
12
ned.Theely as aagnosticoid andaltypesPanicoid
op row:grasses,ed bars
eresultprovideseswereon. Thepatchesoid sub‐
13
Figuresamplephytoli
Of partSpinifeofspinthesiteSpinife(which
Table1
Site
FMGKA
FMGKA
FMGKA
FMGKA
FMGKA
FMGPA
Figuresample
17:Graphe (and acrithscounte
ticular intexongrindifexarepres.Thissugx and Acaisveryhig
1:Abundan
ARIII06‐1
ARIII06‐1
ARIII06‐4
ARIII06‐5
ARIII06‐5
ALVII06‐0
18 showsesfromthe
showingthoss the siedacrosste
erest are tingpatcheresentatalggests(butcia may ngh)butrath
nceofphyto
Numgrinpatsite
8 26
9 4
0 2
0 14
5 20
02 13
s a graphicKARIII06
hecomparix differententransects
the low inswithinthllsitesbuttdoesnotot simplyhertocultu
olithsatsit
mberndingches at eace
cal represe6‐19site.
isonbetwet sites), bs.[Wallis2
ncidence ofhesamesittheirpresunequivocbe relateduralselectio
tes.
of
ch
PatcheAcaciapresen
1
1
0
2
1
0
entation of
enphytolitased on to008]
f Acacia antecomplexsencevariecallydemond to their aonattimes
es withant
PS(p
2
4
2
1
1
6
f the distin
thabundanotal numb
nd the var(Table1).satgrindinstrate)thaabundanceinthepast
PatcheswiSpinifex(spheroidspresent
26
4
2
13
19
6
nctive phy
nceineachbers of dis
riable presSpheroidsingpatchesatthepres in the lant.
ith
s)
Chlorito Parelativabund
EvenGP46
High
High
Tendineven
Evenvariatpatche
Variatpatche
ytoliths in
14
residuestinctive
ence ofstypicalswithinsenceofndscape
idoidanicoidvedance
except
ng
bution ines
tion ines
residue
Figure
AlthougconsistChloridphytolihomogChloriddegree(water,possibl
Figure
Unfortuincorpomateriaaction.presennotpronot metherefoParr 2
18:Phytoli
gh only foutency in thdoidgrasseiths in reenous,withdoidgrasseto which, wind andletodemon
19:Phytoli
unately theorated intoal,asopposWhilethecewas theocessburnean it is aore more li2006). Nev
ithdiagram
ur sampleshe presences,withversidue samhthevarioes,withonlresidue sad fire) is dnstrateAbo
ithdiagram
ere is no eo a grindinsedtothospresenceoeresultofwtgrasses),always poikely the rvertheless,
mofresidue
swere exace of spinrylittleinpmples fromusmorpholyverylimamples midifficult tooriginalpre
mofresidue
easyway tong patch resethathaveofburnt(stawindrathethe fact thssible to aresult of dethe exam
esamplesf
amined fromnifex grasseputfromPam the FMGologicaltypmitedinputight be affdetermineeferencefo
esamplesf
o distinguiesidue as aesettledonained)phyer thanhumhatburninassume uneliberate pmination of
fromFMGK
mKAR IIIes (ie sphanicoidgraG KAR IIIpesindicatifromspinifected by le with thisrparticula
fromFMGK
ish betweea result ofnthesurfaytolithsinamanagentgdoesnotnstained pplant procef ‘off‐site’
KARIII06‐
06‐19, theheroid typeasses.IncoI 06‐50 sngamixtuifexgrassesocal taphodata set argrasstaxa
KARIII06‐
n phytolithf human prcefortuitouaresiduems(sincepetalwayscaphytoliths aessing activcontrol s
‐19.[Wallis
ey show ree phytolithontrast,dissite are alureofPanics(Figure1onomic conand it is tha.
‐50.[Wallis
hs that havrocessing ouslythrougmightindicaeoplegeneause staininare unburvities (thouamples (ie
15
s2008]
elativelyhs) andstinctivell quitecoidand19).Thenditionshus not
s2008]
ve beenof plantghwindatetheirrallydongdoesrnt, andugh seee those
16
collected from the rock surface adjacent but not on grinding patches) might allowelucidationofthisissue.
Discussion
Taphonomic issues notwithstanding, the phytolith evidence provides support for theproposition that inallcases thesampledgrindingpatch featureswereutilised for thegrindingofplantmaterials.Starchgrainswereveryrareandnotlikelytosurviveopenairconditions.Noochrestainsorparticleswereobserved,noranyothersignificantuse‐residues.
Thephytolithanalysisshowsthattheplantmaterialprocessedonthegrindingpatcheswas similar in each case, being typically grasses of the Panicoid and Chloridoid sub‐families. Moreover, usewear on the grinding patches is consistent with experimentalwearpatternsfromgrindingseeds.
ExtensivebedrockgrindingpatchesareknowninGulfcountryofwesternQueensland(Gorecki and Grant 1994). A grass seed grinding function for these Pilbara grindingpatches (rather than ochre grinding) is not surprising particularly given the polishedsurfaces noted by previous researchers, and the extensive distribution and long timedepthofgrindingtechnologyinAustralia(Fullagaretal.2008;Goreckietal.1997).Noris it surprising to find phytoliths in abundance (see Hart andWallis 2003). What issurprising is the evidence of spinifex phytoliths and a rare archaeological example ofpossibleexploitationofspinifexseedsforfood.
There are about 14 species of Triodia and Plechtrachne genera (commonly calledspinifex) in central Australia and it is notoriously difficult to determine species (Latz1995: 288). There are at least three species in the Pilbara: Triodia wiseana (hardspinifex),Triodiapungens(softspinifex)andTriodiaepactia(softspinifex).AboriginalpeopleuseSpinifex foranextraordinaryrangeof things: food(seedsand internodes),medicine(i.e. resin impregnatedanthillsandsmoke), shelter,bedding(!),glue (resin)for tools andornaments,waterproofing of rafts, huntinghides, torches and firesticks,nets(hardspinifexclumps)andfibres(Gott1992;JuluwarluAboriginalCorporationnd;Latz 1995). Pitman andWallis (2012) list 11 main categories including reference tospinifex processing using stone to grind clumps of leaves (for fibre and string) andseeds (for food). The presence of spinifex phytoliths on grinding patches raises aninterestingquestionabouttheusebyAboriginalpeopleofspinifexseedsinthePilbaraandelsewhereinAustralia.BethGott’sdatabaseofAboriginaluseofplants(Gott1992)documentedfewspecificreferencestogrindingspinifexseedsinsemi‐aridmarginsofthe continent: in northern Flinders Ranges (Cleland and Johnston 1939) andnorthwesternNSW(Turner1905).
17
IncentralAustralia,Latz(1995:291)notedthatthe‘Warlpiriarereputedtoeatspinifexinternodesintimesofhardshipbutconsiderthematasteless,inferior,stopgapfood....Aboriginalpeopleinthisareadenyanyuseofspinifexseedsforfood’.
InnorthwesternAustralia,intheHamersleyPlateauofthePilbara,JuwularluAboriginalCorporation (nd:118) documented edible seeds including Acacia inaequilatera, colei,pyrifolia,tumida,Panicumdecompositum,Calandrinapolyandra,PortulacaoleraceaandEucalyptus camaldulensis; but no spinifex. However, Brehaut and Vitenbergs (2001:146)documentthatedibleseedsreportedbytheGurumaelders includedhillspinifex(Triodiasp.) (Gurumaname:paru).[ThislistofedibleplantswascompiledmostlybyPeter Stevens and Nelson Hughes with identification assistance from Stephen vanLeeuwen and Michael Hughes fromWestern Australia’s Department of ConservationandLandManagement.]
ThereisalsoindirectevidencethatSpinifexseedsweregroundforfoodinthePilbara.AlthoughVeth(1993)andWalsh(1987)notednospinifexseedsintheMarturesourceschedule, there is evidence from the Burrup. Bird and Hallam (2006:5) referred toTurner(1981)andreportedthat ‘AstudyofthegrindingpatchesrecordedduringtheDampier Archaeological Project in the early 1980s showed that they were mostcommonincampingareasclosetospinifexgrasslands,suggestingthattheyweremainlyusedforgrindingspinifexseedsintoflour.Manygrindingpatcheshadclearlybeenusedoverlongperiodsoftime,fromtheamountofwearandthefactthattheirsurfaceshadoften been rejuvenated and re‐roughened through pecking or incising lines.’ TheJaburara Heritage Trail brochure also says Aboriginal people harvested spinifex forseeds.ItislikelythatspinifexseedswereusedforfoodinthePilbaraparticularlywhennothingelsewasavailableintherequiredquantityatparticulartimesoftheyear.
PeterVeth(Vethetal.1993andindiscussion)hassuggestedthatthesemi‐aridmarginsaroundthearidcoremayhavebeenhardertoliveinatcertaintimesbecausetheyarelesspredictable (whenandwhere rainfallhappens); and largeaggregationsofpeopleclose to the grinding patches are suggested by the vast body of engravings,which isindeedthecaseintheWoodstock/Abydosstudyarea.Followingthisargument,bedrockgrindingpatchesonthishugescaleareasignatureofsubstantial foodproduction(i.e.seed cakes or damper) to feed large gatherings, made possible by the peculiarconfigurationofsocialnetworks,seasonalresourceavailability(waterandgrassseeds),androckformations(bothgranitedomesforgrindingpatchesandgranophyrebouldersforrockart.).Basedonethnographyandoraltradition,itislikelythattheselargeareasof intensive seed processing reflect women’s activities, to feed families involved inceremoniesassociatedwiththerockart.Domesticcampsitesarelikelytobeassociatedwiththeseseedgrindingactivities.
Conclusions
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Other than noting the presence of grinding patches andmeasuring their dimensions,researchintoAboriginalgrindingpatchesistypicallyminimalinAustralia.Inthisstudywe present a methodology for recovering PVS peels of grinding stone usewear andaqueous solutions of phytolith residues in order to allow the further study of suchfeatures to assist in the determination of their possible function(s). Seed grindingexperimentswereundertakenwithgraniteanddoleritetocomplementothertool‐useexperiments.Usewearstudyof95grindingpatchesat10sitelocationsindicatesthatallwereprobablyusedforgrindingseeds,althoughtheincidenceofstriationsandpolishdevelopment is variable andmay relate to different task conditions, or, alternativelyothertaskssuchastheprocessingofspinifexleavesandstemsforfibres.
Phytolithanalysisofresiduesrecoveredfromthesurfacesofgrindingpatchesindicatesthedominanceofgrassphytoliths.Despiteunresolvedtaphonomicconditions inopensite settings with likely contamination from rain and wind, the grass phytolithassemblagesupports theusewearstudyandsuggests theuseofSpinifex (TriodiaandPlechtrachnegenera)inthePilbaraforseeds.Newmicro‐stainingtechniquesdevelopedby Birgitta Stephenson (2011) have high potential for reliable identification othergrindingstonetracesandfurtherevaluatingthefunctionofthesesites
A high frequency and extensive distribution of grinding stones (including bedrockgrinding patches) are probably linked intimately with food production for largegatheringsofAboriginalpeople.
Acknowledgements
Initial fieldwork for this study in December 2006 included Karriyarra communitymembers Andrew Gordon and Bruce Bung, Alan Watchman, Boone Law, RichardFullagarandGavinJackson(whoundertooksubsequentfieldwork).
Foradviceandpermissionstopublishthisinformation,weareparticularlygratefulto:
TheKarriyarrapeople(inparticularDonnyWilson,Elder)whohasbeensupportiveofouraimtolearnhowpeoplewereliving‘insuchhardcountry’andtoletotherpeopleknow. He discussed the presented paper and carefully edited some of the text andimages.
ThePalykupeople(inparticularDavidMilroy,ChairPalykuNativeTitleWorkingParty).Davidaskedmetoincludethistextwiththepaper:‘OurRockart,grindingpatchesandcultural material are not only a record of Palyku past, but also an essential part ofPalyku'spresentdayandfuture.WethankRichardfortakingthetimetotalktousandwehopethismaterialwillhighlighttheneedforfurtherprotectingPalykuHeritageandCulture.’
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WealsothankAlexaMorcombe,FMGforpermissionstopublishthedetailincluded.Wealso thankvariouspeoplewhoprovided logistical supportand/or technicaladviceonthis paper, including: ShaunCanning (ACHM); Phil Czerwinski (ACHM);NealeDraper(ACHM);Gavin Jackson (GJPtyLtd);BooneLaw(ACHM)whosephotographsarealsodulyacknowledged;BlairMcGlew(FMG);PeterVeth(ANU),andAlanWatchman.
We are both indebted to Beth Gott whose friendship and research have beeninspirational. Her botanically focussed publications and meticulous databases haveinspired us here to focus our discussion on one plant taxon, spinifex. We are alsograteful to organisers and fellow participants at: A Symposium inHonour of Dr BethGott, Ethnobotanist, Friday 12th September 2008, 9:30am – 5:30pm at the KoorieHeritageTrust,MelbourneVictoria.
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