quickly赛酷ocr

Presentedatthesymposium"AnOverviewofResearchatWatsonBrake:AMiddleArchaicMoundComplexinNortheastLouisiana"duringthe53rdAnnualMeetingoftheSoutheasternArchaeologicalConference,Birmingham,Alabama.
Copyright1997OCRCarbonDating,Inc.
AllRightsReservedThisdocumentmaybedistributedforacademicandpersonaluseonly.
OCRCARBONDATINGOFTHEWATSONBRAKEMOUNDCOMPLEXDouglasS.
FrinkArchaeologyConsultingTeam,Inc.
OCRCarbonDating,Inc.
P.
O.
Box145EssexJunction,VT05453ABSTRACTInformationconcerningtheageofmoundconstructionatWatsonBrakeiscriticaltotheinterpretationofthesite.
WerethemoundsandridgesconstructedduringtheMiddleArchaicPeriodastheartifactssuggestOrweretheyconstructedatalatertimefromsoilswhichincludeMiddleArchaicPeriodartifactsThesequestionsarecriticalintheinterpretationofhumanbehavioratthesite.
TheOCRCarbonDatingproce-dureevaluatesthepedogenicdegradationoforganiccarbon,andtherebyprovidesaninsituageestimateofthesoildeposit.
Over200OCRsamplesfromthreemoundsandtwoconnectingridgesprovidedetailedinformationabouttheageandsequenceofmoundconstructionatWatsonBrake.
INTRODUCTIONTheprecedingpapershaveprovideduswiththephysical,geomorphologic,andped-ologicalcontextsoftheWatsonBrakecomplexofmoundsandconnectingridges.
Laterpaperswillprovidedetailsconcerningtheculturalmaterialrecoveredduringrecenttestingatthissite.
ThispaperaddressesthetemporalcontextofthemoundandridgeconstructionanditsabandonmentusingresultsobtainedfromtherecentlydevelopedOCRcarbondatingprocedure.
UniquelyspuriousresultsfromthemoundandridgefilldepositssuggestcertainhumanbehaviorattheWatsonBrakecomplex.
Traditionally,moundconstructionhasbeenconsideredaculturalexpressionrestrictedtotheWoodlandandlaterperiodsofNativeAmericanculture.
NotedexceptionssuchasPovertyPoint,aLateArchaicPeriodsite,haveprovedbothproblematicandfunda-mentaltohypothesisdevelopment.
Detailedlandarchitecturemusthaveevolvedfromalessdistinctiveprecursor,butexamplesofearliermoundconstructionsarenotreadilyidentifiable.
Moundscontainingartifactsfromearliertimeperiodsareknown,buttheylackinsitucarboncontainingculturalfeaturesthatcanbe14Cdated.
Whetherthemoundswereconstructedduringearlierperiodsastheartifactssuggest,orwereconstructedfromsoilscontainingearlierartifactshasremainedundetermined.
Insituhearthorgarbagepitfeaturesarerareinandbelowmoundfills.
Theirdefini-tionandexistenceisoftendoubtedandsubjecttocriticismasbeingonlysecondaryfilldeposits.
Suchunresolvableargumentsareunnecessary.
Themoundsthemselvesareprimaryinsituculturalfeaturesthathaveundergonepost-depositionalchanges.
Un-derstandingthesechangesprovidesameanstodirectlydeterminethetemporalcontextofboththeirconstructionandabandonment.
TheOCRCarbonDatingprocedure,developedbytheArchaeologyConsultingTeam,measuresthesite-specificrateofbiodegredationoforganiccarbon,eitherassoilhumicmaterialorascharcoal.
Thebiologicalrecyclingoforganiccarbonisfundamentaltonearlyallbiologicalsystemsonthisplanet.
Whilesomeformsoforganiccarbon,suchasfreshorganicmatter,arequicklyrecycled,othermoreresistantforms,suchashu-musandcharcoal,arerecycledatamuchslowerrate.
Thisrecyclingfollowsalinearprogressionthoughtimewhenconsideredwithinthesite-specificcontext,andin-cludesthefactorsthatinfluencebiochemicaldegredationoforganiccarbon.
Charcoalandsoilhumicmaterial,oncethoughttobeinert,arebiologicallyrecycledataslowbutmeasurablerate.
Theeffectofthebiochemicaldegradationofcharcoalandsoilhumicmaterialismea-suredbyaratioofthetotalorganiccarbontothereadilyoxidizablecarboninthesoilsample.
Ingeneral,asthetotalamountoforganiccarbondecreasesthoughtimeduetorecycling,therelativepercentageofreadilyoxidizablecarbonincreases.
ThisratioiscalledtheOxidizableCarbonRatio,orOCR.
Therateofbiochemicaldegradationwillvarywithinthespecificphysicalandenvironmentalcontextsofthesample.
Anageestimateoftheorganiccarbonisdeterminedthroughasystemsformulathataccountsforthebiologicalinfluencesofoxygen,moisture,temperature,carboncon-centration,andthesoilreactivity.
Residualinfluencesonthissystemareincludedthroughastatisticallyderivedconstant.
METHODSANDPROCEDURESAtotalof200soilsamples,obtainedatfive-centimeterintervalsbelowthesurface,wereanalyzedtodetermineanageestimatefortheconstructionandabandonmentofthreemoundsandtworidgesoftheWatsonBrakecomplex.
Soilsampleswereob-tainedfromMoundBandRidgesystemA-Kduringthe1995fieldseason,andfromRidgeC-B,MoundD,andtheapronofMoundAduringthe1996fieldseason.
Samplingextendedfromthesurface,throughthemoundandridgefillsoils,andintotheburiedoriginalsoilsurface.
Soilsamplesweighing100gramswereextractedatfive-centimeterintervalsbyDr.
Saundersduringtestexcavations.
Allsampleswereair-driedtoarrestbiochemicalaction,andshippedtoourlaboratoriesinVermont.
Soiltexturewasdeterminedbydryscreening,withthemeantexturecalculatedbythepercentageofweightforeachfractionaccordingtoUSDAstandardmeshscreensizes.
SoilpHwasdeterminedfroma1:1,soil/waterpaste.
TotalcarbonwasdeterminedbytheBallLossonIgnitionprocedure(Ball,1964),andthereadilyoxidizablecarbonwasdeterminedbytheWalkleyandBlackwetcombustionprocedure(Walkley,1935;WalkleyandBlack,1934).
MeanannualtemperatureandmoisturewerebasedontheNationalOceanicandAtmosphericAdministration(NOAA)NarrativeSummariesfortheperiodof1941to1975(Ruffner,1978).
AllOCRDATEageestimatesareexpressedasMRTs,orthemeanresidencetimeforalltheorganiccarboncontainedinthesample.
Astheactualagerangesandrelativeamountsofyoungandoldcarbonarenotdetermined,statisticallymeaningfulconfidenceintervalscannotbecalculated.
RESULTSThesoilisalive.
BythisstatementIdonotmeanthatindividualgrainsofsandhavesentience.
Rather,thesoilbodywithitsinteractionofmicrobialbiologyandatmo-sphericchemistry,maybeseenasasystemthatisself-regulating,evolvingandgrow-ing.
AswelookatthemoundsandridgesatWatsonBrake,weseesoils,oncealiveinanotherspatial-temporalcontext,thathavebeenmoundedupintoadeadheapofmineralandorganiccorpses.
However,almostimmediatelyafterthelastbasketloadoffillisappliedtothepile,anewsoilbodyisconceivedandgrowthcommences.
UsingtheOCR-RatioandthevariablesfromwhichtheOCRDATEiscalculated,theextentanddurationofgrowthinthiscurrentsoilbodycanbedeterminedandseparatedfromthecorpsesoftheformersoilbodies.
Post-abandonmentbiochemicalpedogenesis,orsoilgrowth,isevidentwithintheupperportionsofthemoundsandridgesextendingintotheupperportionsoftheBthorizon.
Thishorizonslowlymigratesdownwardandactsasabarriertooxygenper-meationandthusthebiodegradationofcarbon.
OCRDATEageestimatesforthethreemoundsrangefromanaverageof480yearsbeforepresentatthesurface,toanaverageageof4866yearsbeforepresentatthetopoftheBthorizon.
OCRDATEageestimatesforthetworidgesystemsrangefrom197yearsbeforepresentatthesurface,toanaverageageof5229yearsbeforepresent.
TheuppermostsamplesdemonstrateanexpectedyoungMRTvalueduetothepredominanceofrecentorganiccarbonfromforestvegetation.
TheOCRDATEofthesamplesfromtheupperportionoftheBthorizonrepresentthemaximumdepthofbiochemicaldegradationoforganiccarbonspost-moundconstruction.
TheyoungerOCRDATEestimatesobtainedfromtheuppermostlevelsoftheridgesystemsascomparedtothemoundssuggeststhatminorsoildeflationhasoccurredonthetopographicallyhighermounds.
Ifso,thentheactualageofthemoundsarelikelysomewhatolderthan4866yearsbeforepresent,butyoungerthan5229years.
Formerpedogenicallyactivesoilsarelocatedbelowthemoundandridgefills.
Theageofthesub-moundsoilhorizonsindicateatimepriortomoundandridgeconstruc-tion.
Thegrowthofthesesoilswasarrestedatthecommencementofmoundbuilding.
Extendingourmetaphor,thesesoilsweresuffocatedbytheoverburden,andleftinplacedead.
TheOCRDATEestimatesfortheburiedsurfacesrangefrom5289to5778yearsbeforepresent.
Theseageestimatesrepresentatimesomewhatbeforetheeventofsuffocation,astheorganicswithinthesampledsoilhorizonsconsistsofbothyoungandoldcarbonthataccumulatedduringthesoilbody'slifetimeofactivepedogenesis.
Weseeasimilartime-laginthepresentsoilsurfaceofthemounds,andestimatethattheeventofmound-fillingoccurredaboutthreehundredyearsaftertheOCRDATEestimatesfortheburiedsurface.
Theaverageageestimateincludingthe300yeartime-lag,fortheeventofburialforthesub-moundsoilbodyisabout5180yearsbeforepresent.
Theageofthenon-pedogenicallyactive,ordeadandtransposedsoilsconstitutingthemoundandridgefills,maybeexpectedtocoverarangeofdatesbotholderandequivalenttotheOCRDATEageestimatesobtainedfromtheupperportionsoftheBthorizon.
Themaximumageofthemoundfillsoilswilldependonthedepthofborrowexcavations.
Ifthemoundswereconstructedfromsub-soilsaswellassurfacesoils,theageofthemoundfillsoilswillpre-datetheburiedpedogenicsoilhorizon.
TheOCRDATEageestimatesforthefillsoilsrangebetween5087and6407yearsbeforethepresent,withameanof5590years.
SoilswithabnormallyhighOCR-ratioswerepresentinallfiveprofiles,indifferentquantitiesandpositionswithintheprofileofnon-in-situ-pedogenicmoundandridgefills.
OCR-ratiosgreaterthan5.
5arenormalforsoilsobtainedfromananaerobiccontext.
TheanaerobiccharacteristicsofthesehighOCR-ratiosoilscannotbeex-plainedasaninsituphenomenonbecausetheirpositionsvarywithintheprofile.
Rather,itislikelyinheritedfromthesoilbody'splaceoforiginpriortoexcavationandrelocationtothemounds.
Insummary,basedonOCRdatafrom200samples,thethreemoundsandtworidgesatWatsonBrakewereconstructedwithin200yearsof5180yearsbeforepresent,theaverageestimatedageofdeathofthesub-moundsoilbody,andabandonedwithin200yearsof5010yearsbeforepresent,theaverageageofthegrowth,orpedogenesis,intheuppermoundsoilbody.
DISCUSSIONTheinformationobtainedfromthedetailedsoilanalysesatWatsonBrakecanprovidemorethansimplyatemporalcontextfortheconstructionandabandonmentoftheMoundsandRidges.
Basedonthevaryingcharacteristicsofthemoundfillsoils,weconcludethatbothdrysurfacesoilsandwetsubsurfacesoilswereexcavatedtocreatethemounds.
Moundsaretraditionallyperceivedasintentionallandarchitecture,ormonuments.
Theorientationanddiversityofstylesexhibitedbymany,particularlythemorerecentmoundcomplexes,supportsthisview.
However,thearchitecturalcharac-teristicsofearlymoundsmaybesecondarytotheprimaryculturalpurpose.
Drysoilsaremucheasiertoexcavateandtransportthanwetsoils.
ThisdifferenceismagnifiedwithfinersoilssuchasthesiltsandclayscomposingtheWatsonBreakcomplex.
WhiletheinvestmentofenergyusedtobuildthemoundsandridgesatWatsonBreakisobviousonthelandscape,theinvestmentinexcavationactivitiesmaybeeasilyoverlooked.
Thepresenceofsurfacedrysoilsandsubsurfacewetsoilswithinthemoundandridgefillssuggeststhatrelativelydeepexcavationpitsexistwithintheadjacentfloodplain.
Evidenceoftheseborrowareasarelikelyburied,asthetimeofhypothesizedpitexcavationpre-datestheleveesandaggradationofthefloodplaincausedbythecoursechangesoftheArkansasRiver.
ThemeandersandoxbowswhichhaveresultedfromthediversionoftheArkansasRiveraround4,800yearsago,providednaturalfishponds.
Wehypothesizethatpriortothepresenceofthesenaturalexploitableniches,syntheticfishponds,orchannels,mayhavebeenintentionallyexcavatedbythebuildersofWatsonBraketoaugmenttheexistingriverineniche.
ThecomplexofmoundsandridgesatWatsonBrake,whilelikelyservingsomesecondaryculturalpurpose,mayalsobeviewedasspoilpilesasso-ciatedwiththeprimaryactivityofhabitatmanipulation.
RemotesensingandsoilcorestudieswithintheadjacentfloodplainareamayrevealthesehypothesizedborrowareasbeneaththemorerecentalluvialdepositsoftheArkansasandOuachitaRiver.