Direct radiocarbon dating of megalithic paints from north-west Iberia.

Direct radiocarbon dating of megalithic paints from north-west Iberia. On the Iberian Peninsula, post-Palaeolithic paintings--in contrastwith Palaeolithic images-have received scant attention from the AMS AMS - Andrew Message System radiometric technique. In fact, only one radiocarbon date consistentwith generally expected values has been previously determined on apainted megalith megalithHuge, often undressed stone used in various types of Neolithic and Early Bronze Age monuments. The most ancient form of megalithic construction is probably the dolmen, a type of burial chamber consisting of several upright supports and a flat roofing slab. ; charcoal from a black-painted tomb panel in a corridorat Antelas, Viseu, Portugal, was dated to 4655 [+ or -] 65 BP (Cruz1995a,b). Here we present nine accelerator mass spectrometry accelerator mass spectrometryn.Mass spectroscopy in which a particle accelerator is used to disassociate molecules, ionize atoms, and accelerate the ions. (AMS)radiocarbon dates for megalithic meg��a��lith?n.A very large stone used in various prehistoric architectures or monumental styles, notably in western Europe during the second millennium b.c. paintings in north-west Iberia (Figure1), placing these paintings as the oldest known examples of prehistoricart in Galicia (northwest Spain). Two of us (FCR FCRfeed conversion rate. & RFV RFV Relative Feed Value (quality of hay)RFV Radial Force Variation ) haveactively investigated north-west Iberian megalithic art since 1998,systematically locating and recording pictorial remains (doubling thenumber of known sites in the Galician area) (Carrera Ramirez &Fabregas Valcarce 2003). [FIGURE 1 OMITTED] The progressively widespread use of radiocarbon dating using AMSsince the late 1980s has overcome an important barrier to dating rockpaintings--the ability to analyse small amounts of material available ina paint sample. AMS has opened new possibilities for dating thosepaintings that contain an organic component (charcoal, blood,fats/oils). The first AMS radiocarbon date for a rock painting wasobtained for a charcoal painting located in South Africa (van der Merweet al. 1987). Since that time, researchers have used AMS to radiocarbondate rock paintings throughout the world (see Rowe 2001 for a review ofpublished dates). Paintings on stone, whether on a cave wall or a megalithicmonument, pose serious and unique challenges for accurate dating: (1)images are often painted on limestone, a carbon-containing mineral; (2)the amount of carbon from the paint sample available for dating issmall-orders of magnitude less than a typical artefact See artifact. ; (3) little isknown about binders and/or vehicles used in making ancient paints; (4)physical contamination must be removed; and (5) organic materialunassociated with painting activity can occur in unpainted rock (seeRowe 2001; Bednarik 2002; Steelman et al. 2002; Steelman & Rowe2005, for further discussion concerning pictograph pictograph - pictogram dating, as well asPettit & Bahn 2003; Valladas & Clottes 2003, both published inAntiquity). Charcoal paintings are most commonly dated, but theplasma-chemical extraction method also allows the dating of pictographswith inorganic pigments (if an organic material was added to the paint).Our (MWR MWR Morale, Welfare and RecreationMWR Ministry of Water Resources (China)MWR Monthly Weather ReviewMWR Microwave RadiometerMWR Multiple Worksite Report (US Department of Labor)MWR Microwave Radiometry & KLS KLS KLM Luchtvaartschool (KLM Flight Academy; Eelde, The Netherlands)KLS Kit Letter DesignatorKLS Kernel Lockdown ScriptsKLS Key List Server ) laboratory has repeatedly attempted to verify ourresults by dating radiocarbon standards with previously measured agesand rock paintings for which an archaeologist had some inferred agerange (Rowe & Steelman 2001). Using plasma-chemical extraction and AMS, we have obtained nineradiocarbon dates for paint samples taken from six Galician megalithicmonuments (Figure 2). These results stand out by their general agreementwith one another. [FIGURE 2 OMITTED] Description of monuments studied We sampled black paints from gneiss gneiss(nīs), coarse-grained, imperfectly foliated, or layered, metamorphic rock. Gneiss is characterized by alternating light and dark bands differing in mineral composition and having coarser grains than those of schist. , granite and schist schist(shĭst), metamorphic rock having a foliated, or plated, structure called schistosity in which the component flaky minerals are visible to the naked eye. dolmen dolmen(dŏl`mĕn, dōl–)[Breton,=stone table], burial chamber consisting of two or more upright stone slabs supporting a capstone or table, typical of the Neolithic period in Europe. See megalithic monuments. stones at Pedra da Moura, Casota do Paramo pa��ra��mo?n. pl. pa��ra��mosA treeless alpine plateau of the Andes and tropical South America.[American Spanish p��ramo, from Spanish, wasteland.] , Pedra Cuberta, Maimoa deMonte dos Marxos, Forno do Mouros, Anta de Serramo, Coto dos Mouros andDolmen de Dombate, all located in Galicia (north-west Spain). Thesemonuments are all passage graves, consisting of a polygonal chamber anda short corridor (Figure 3). Typically, the orthostats (vertical uprightwall stones) forming the corridor are shorter and smaller than those ofthe chamber. Unfortunately, these monuments have suffered from vandalismin which some stones were removed as construction material. Inspectionof the accessible orthostats reveals visible remnants of paint; however,the graphic images are often highly degraded and unrecognisable. [FIGURE 3 OMITTED] Red and black geometric paintings were typically applied over awhite plaster coating the interior of the stone monument. We collectedonly black paint samples, except for one red paint sample from Dolmen deDombate. Pigment of black paint was identified as charcoal by thecharacteristic structure of burnt wood observed under an opticalmicroscope, as well as by the disappearance of black colour noted duringplasma oxidation. In the limited attempts to characterise megalithicpaint manufacture, dark pigments have consistently been identified aswood charcoal (Shee Twohig 1981; Bello Dieguez 1995). Sample collection Samples were removed from the stones using a surgical scalpel, andthen placed directly into a sterilised glass vial. The decision of howmuch sample to remove was subjective, and varied depending on whetherthe material removed was primarily paint or, as more commonly occurred,included a portion of the plaster layer. The quantity of samplecollected was kept to a minimum, typically less than 30mg and often muchless, of the order of 10mg, when the sample included only the surfacelayer rich in paint. We attempted to collect samples from areas withlittle visual significance and which appeared to be free from biologicalactivity (algae algae(ăl`jē)[plural of Lat. alga=seaweed], a large and diverse group of primarily aquatic plantlike organisms. These organisms were previously classified as a primitive subkingdom of the plant kingdom, the thallophytes (plants that , lichens, etc.). In some cases, we first cleaned thesampled area, always using mechanical means (small brushes) and nowater. Pedra da Moura (Vimianzo, A Coruna) Paint sample M1 (~26mg) was collected from the second orthostat onthe left side of the corridor (L2). It contains none of the whiteplaster and is composed primarily of black paint and accretion minerals. Casota do Paramo (Boiro, A Coruna) Paint sample M2 (~33mg) was taken from the base of the firstorthostat on the left side of the chamber (C 1) and consists of as muchpreparative pre��par��a��tive?adj.Serving or tending to prepare or make ready; preliminary.n.Something that prepares for or acts as a preliminary to something following. white plaster as black pigment. Pedra Cuberta (Vimianzo, A Coruna) We collected paint sample M3 (~13mg) from Pedra Cuberta. Thewell-preserved black paint was collected from orthostat L1, the first onthe left side of the corridor. Mamoa do Monte dos Marxos (Rodeiro, Pontevedra) No longer in existence as an intact monument due to severevandalism, the orthostats have been moved to the Museum of Pontevedra.Of significant interest is the presence of two distinct layers of paintapplied on seven of the twelve orthostats examined. Two paint sampleswere removed from orthostat 7: sample M4 (~6mg) was from the underlyinglayer of paint (between plaster and surface paint) and sample M5 (~16mg)was taken from the overlying overlyingsuffocation of piglets by the sow. The piglets may be weak from illness or malnutrition, the sow may be clumsy or ill, the pen may be inadequate in size or poorly designed so that piglets cannot escape. surface layer. Forno dos Mouros (Toques Toques is a municipality in the Spanish province of A Coru?a. It has a population of 1580 (Spanish 2001 Census) and an area of 78 km².[ edit ] Municipalities of A Coru?a , A Coruna) The preservation of the red and black horizontal zigzag paintingsis good on one of the uprights (C1, Figure 4), but very fragmentary onthe rest. Sample M6 (~22mg) was collected for dating from the C1 uprightin 1998 and consists of black paint made of charcoal. [FIGURE 4 OMITTED] Anta de Serramo (Vimianzo, A Coruna) Two small paint and plaster samples (each ~20mg) were taken fromthe lower part of upright C1, close to the soil, making it verydifficult to obtain a clean extraction. This fact might explain theoutlying radiocarbon result. Coto dos Mouros (Rodeiro, Pontevedra) There is evidence of superimposition In graphics, superimposition is the placement of an image or video on top of an already-existing image or video, usually to add to the overall image effect, but also sometimes to conceal something (such as when a different face is superimposed over the original face in a of paint, as at Monte dosMarxos. Sample M10 (129rag) contained multiple layers and sample M11(114mg) was from the underlying paint layer. During sample collection,we noted a black coating covering the interior of Coto dos Mouros, whichseemed to be due to the burning of at least one tyre inside themonument. While both samples M10 and M11 were removed from areas awayfrom the black coating and did not contain any visible soot, we must becautious about radiocarbon dates from this monument. Dolmen de Dombate (Cabana, A Coruna) Preserved paintings only occur on those surfaces covered by thesoil prior to excavation. Two paint samples were collected from Dolmende Dombate, but unfortunately we were unable to determine their age. Thefirst sample consisted of black paint (M8) taken from orthostat L2, andwas accidentally lost during analysis. A second sample consisting ofkaolin kaolin(kā`əlĭn): see china clay. plaster plus some red pigment (M9) did not have sufficientorganic material for an AMS radiocarbon date. Finally, we radiocarbondated an organic residue from a pot recently excavated, assigned to theoldest occupation phase and, thus, providing us with a post quem datefor the building of the passage grave and, presumably pre��sum��a��ble?adj.That can be presumed or taken for granted; reasonable as a supposition: presumable causes of the disaster. , its interiordecoration. Experimental procedure Each paint sample was viewed under an optical microscope to detectany incorporated extraneous materials. Microscopic fibres were observedin the majority of the paint samples (M2, M3, M6, M7, M8, M11) andremoved with tweezers tweezersAn instrument with pincers used to grasp or extract. See Optical tweezers. . We believe the fibres are from plant rootletsthat are actively damaging the buried stones. Sodium hydroxide sodium hydroxide,chemical compound, NaOH, a white crystalline substance that readily absorbs carbon dioxide and moisture from the air. It is very soluble in water, alcohol, and glycerin. It is a caustic and a strong base (see acids and bases). washes inan ultrasonic water bath were performed following the procedure outlinedin Steelman et al. (2002). While we rarely encounter humic hu��mic?adj.Of, relating to, or derived from humus.Adj. 1. humic - of or relating to or derived from humus; "humic acid" acids in rockart samples, we did observe a colour change of the base wash indicatingthe presence of humic acids in these megalithic paint samples as mightbe expected for buried materials. Multiple base washes were performeduntil no colour change was observed. In our procedure, decomposition ofcarbon-containing minerals such as carbonates and oxalates into carbondioxide carbon dioxide,chemical compound, CO2, a colorless, odorless, tasteless gas that is about one and one-half times as dense as air under ordinary conditions of temperature and pressure. is prevented by running the plasma at low-temperature (<150[degrees]C). With plasma-chemical extraction, only organic materialis removed for radiocarbon measurements. Megalithic paint samples were subjected to plasma-chemicalextraction and AMS [sup.14]C measurement. With our procedure, alow-temperature oxygen plasma (partially ionised low-pressure oxygen)selectively oxidises organic material in a paint sample, while anyincorporated carbon-containing minerals remain unreacted. The copiousamounts of carbonate and oxalate oxalate/ox��a��late/ (ok��sah-lat) any salt of oxalic acid. ox��a��laten.A salt or ester of oxalic acid. minerals typically included in rockpaintings have no effect on radiocarbon dates when this technique isemployed. With plasma-chemical extraction, only organic material isremoved for AMS radiocarbon measurement. We routinely omit acid washesused by other laboratories, as they are unnecessary with plasma-chemicalextraction (Russ et al. 1992; Chaffee et al. 1994; Pace et al. 2000). Incontrast to our method, acid treatments used in conjunction withcombustion methods may not completely remove carbon-containing mineralsassociated with rock paintings and their inclusion will influenceradiocarbon results (Hedges et al. 1998; Armitage et al. 2001). Organiccarbon in a paint sample is converted to carbon dioxide duringplasma-chemical extraction. This carbon dioxide is reduced over a metalcatalyst to form a graphite target for AMS 14C measurement at LawrenceLivermore National Laboratory's Center for Accelerator MassSpectrometry (CAMS). For Anta de Serramo sample M7, carbon dioxide usedfor the AMS target was combined from two separate paint samples thatwere processed individually. Taken individually the samples did notproduce enough carbon to date, but when combined gave 53[micro]g ofcarbon, sufficient for an AMS measurement. Results The radiocarbon results from this study of megalithic paintings arelisted in Table 1. The AMS laboratory identification number andcalibrated (20 [sigma]) age ranges are also listed. Calibration wasperformed using the OxCal computer program version 3.5 (Bronk Ramsey2000) with atmospheric data from Stuiver et al. (1998). Two radiocarbondates on an organic residue from an excavated pot at Dolmen de Dombateare 4900 [+ or -] 40 BP (CAMS 101903) and 6890 [+ or -] 40 BP (CAMS101904), with a weighted average of 4895 [+ or -] 30 BP and calibratedto 3715-3635 cal BC at 95 per cent (20 [sigma]) using OxCal. Discussion Radiocarbon dating of charcoal paints corresponds to a maximum agefor the creation of the image. While charcoal is the most commonly datedarchaeological material, it dates the death of the plant from which thecharcoal was made. It does not directly date the event of interest, inour case the production of a painting. It is plausible that wood wascollected from a live plant and then burned to make charcoal paint; inthis instance, a radiocarbon date would be contemporaneous withpainting. However, two other situations can occur: old wood and oldcharcoal. The old wood effect occurs when wood may have died long beforeit was burned to make charcoal (Schiffer 1986). Alternately, for thecase of old charcoal, wood could have been burned at an earlier unknowntime and the resultant charcoal used much later to execute a painting(Bednarik 1994). To a first approximation 1. to a first approximation - When one is doing certain numerical computations, an approximate solution may be computed by any of several heuristic methods, then refined to a final value. , our radiocarbon results for charcoalmegalithic paintings are contemporary with published dates for monumentconstruction phases and/or early activity at decorated sepulchral se��pul��chral?adj.1. Of or relating to a burial vault or a receptacle for sacred relics.2. Suggestive of the grave; funereal.se��pul megaliths (Table 2). They are also consistent with a previouslydetermined age of a black painting at Antelas, Viseu, Portugal. Anaverage of primary monument construction and/or utilisation dates fromTable 2 is 4840 BP with a sample standard deviation of 190 BP(approximately 4050-3000 cal BC). This average overlaps with the Antelasdate (Cruz 1995 a,b) and six of our radiocarbon results (for PedraMoura, Casota do Paramo, Pedra Cuberta, Forno dos Mouros and Mamoa doMonte dos Marxos M4 & M5) at 95 per cent probability (2 [sigma]).Our results suggest megalithic monument decoration occurred atapproximately the same time as primary construction. An average of theAntelas date and our six overlapping radiocarbon dates on megalithicpaints is 4930 BP with a sample standard deviation of 220 BP(approximately 4300-3100 cal BC). Our values are therefore consistentwith the first occurrence of passage-graves at approximately 4000-3600cal BC (Alonso & Bello Dieguez 1997: 514) and only slightly laterthan the oldest directly dated single chamber megalith at 5210 [+ or -]50 BP (4230-3940 cal BC) (Cruz 1995a: 92). From Table 1, the temporal agreement between Pedra da Moura andPedra Cuberta paintings is significant because these two monuments areonly 1 km from each other. They are similar in architectural design,decorative technique, and location in the landscape, though clearlydifferent in dimensions. Dates of both monuments also overlap withconstruction of the passage grave of Dombate in Coruna (Alonso &Bello Dieguez 1997), which is about 11 km away. Two monuments showed signs of multiple painting events. Radiocarbonages of paint layers were consistent with the observed superposition su��per��po��si��tion?n.1. The act of superposing or the state of being superposed: "Yet another technique in the forensic specialist's repertoire is photo superposition" . AtMamoa do Monte dos Marxos, the radiocarbon data establish this temporalstratification with an age of 4920 [+ or -] 60 BP for the top surfacelayer (M5) and 5330 [+ or -] 80 BP for the underlying paint layer (M4).Calibrated age ranges for both dates do not overlap at 2 [sigma]. Theage differences in the two layers of paint may be a result ofcontinuous, prolonged use of the monument, without significanttransformations in its structural design. Or, alternatively, it mayrepresent modification of a primary construction to create a larger ormore complex structure, with repainting of the images during this latermodification (Fabregas Valcarce 1995: 104). The painted designs of bothlayers appear to be notably similar, as if ancient restoration of adegraded painting had been intended. At Coto dos Mouros, sample M10 contains two layers of paint and hasan age of 3830 [+ or -] 60 BP, representing a weighted average relatedto the amount of each layer in the paint sample. Paint sample M11 withonly the underlying layer yielded an age of 5540 [+ or -] 70 BEInterpretation of these radiocarbon results from Coto dos Mouros iscomplex, with results for M10 being unexpectedly young and M11 beingquite old. This suggests that M10 has been subject to moderncontamination, perhaps by carbon from vehicle tyres. Incorporation ofcontamination from tyre soot would result in a younger age if naturalrubber was used to make the tyre. Alternatively, if the tyre wasproduced from synthetic rubber, the measured radiocarbon age would beolder than the age of the paint due to the inclusion of [sup.14]C-freecarbon from petroleum raw materials. For the underlying layer (M11), the5540 BP result is older than expected, and like M4 from Monte dos Marxoscould be explained by the use of old charcoal, perhaps coming from anearlier construction, for both dates are roughly consistent with thoseobtained from the earliest single chambers in north-west Iberia. In thisrespect, we must not forget that hidden under the tumulus tumulus(t`myələs), plural tumuli (–lī), in archaeology, a heap of earth or stones placed over a grave. ofDombate's passage grave there were the remains of another, muchsmaller, funerary fu��ner��ar��y?adj.Of or suitable for a funeral or burial.[Latin fner chamber from an earlier building phase at the site. From Cruz (1995a,b), Antelas is the only case where there isradiometric data for both the construction of a structure (5070 [+ or -]65 BP) and the execution of its paintings (4655 [+ or -] 65 BP). Whencalibrated, these age ranges do not overlap at 2 [sigma] suggesting atemporal lag between construction and decoration with a 95 per centprobability that the ages represent different events. It is unknownwhether the radiocarbon date for the painting at Antelas is from asingle layer of paint or successive layers as we observed at Mamoa doMonte dos Marxos, Coto dos Mouros, and perhaps even Dombate and PedraCuberta. Statistically, the two paint layers at Mamoa do Monte Dos Marxosand the Antelas construction and paint decoration dates indicate aninterval between activities. However, there is danger in making suchconclusions with only one radiocarbon date for each material studied.There is no way to determine if any of the measurements are rogue due tocontamination or laboratory error. Conclusions These radiocarbon ages for megalithic paintings agree with theproposed time period for the north-west Iberia megalithic phenomenon(Cruz 1995a; Fabregas Valcarce 1995; Alonso & Bello Dieguez 1997;Bueno Ramirez & Balbln Behrmann 1997), and by doing so, reinforcethis cultural chronology. Megalithic painting may have occurred overseveral centuries or may have taken place over a shorter phase. Becauseof vagaries in the radiocarbon calibration curve during this timeperiod, the calibrated age range intervals are quite large and it isdifficult to resolve differences in calendar ages for these monuments.It is noteworthy that paint samples from eight different monumentsproduce radiocarbon ages that are within 1000 [sup.14]C years of eachother centring around 5000 years BP (3800 cal BC). Though meaningful,these radiocarbon results remain orphans if they are not integrated withother data from future scientific excavations of decorated megalithicmonuments.Table 1. Radiocarbon results for megalithic paint from Galicia andNorth PortugalSample Site CAMS no. [micro] g CM1 Pedra Moura 77761 50M2 Casota do Paramo 77427 50M3 Pedra Cuberta 77923 120M4 Mamoa do Monte: 77924 90 dos Marxos (under)M5 Mamoa do Monte: 77925 210 dos Marxos (surface)M6 Forno dos Mouros 80501 110M7 Anta de Serramo 88195 53M8 (a) Dolmen de Dombate Lost --M9 (b) Dolmen de Dombate Too small 8 (red)M10 Coto dos Mouros 83116 165M11 Coto dos Mouros 83631 100Cruz 1995a,b Antelas OxA-5433 Cal BC ProbabilitySample Years BP (2[sigma]) (%)M1 4980 [+ or -] 70 3950-3640 95.4M2 4740 [+ or -] 120 3800-3100 95.4M3 5010 [+ or -] 60 3960-3690 92.8 3680-3660 2.6M4 5330 [+ or -] 80 4340-3980 95.4M5 4920 [+ or -] 60 3940-3870 5.3 3810-3630 88.2 3560-3530 1.9M6 4900 [+ or -] 60 3910-3870 1.8 3800-3620 87.0 3590-3520 6.6M7 6050 [+ or -] 110 5300-4700 95.4M8 (a) -- -- --M9 (b) -- -- --M10 3830 [+ or -] 60 2490-2130 94.3 2080-2060 1.1M11 5540 [+ or -] 70 4540-4240 95.4Cruz 1995a,b 4655 [+ or -] 65 3650-3300 91.1 3250-3100 4.3(a) No radiocarbon result for this sample because the glass tubecontaining plasma-extracted C[O.sub.2] cracked during sealing.(b) No radiocarbon result for this sample, as there wasinsufficient carbon for AMS dating.Table 2. Radiocarbon dates for strata corresponding to primaryconstruction and utilisation of megaliths with pictorial decoration.All dates are from Alonso & Bello Dieguez (1997), except the Antelasdate from Cruz (1995a) and the organic residue from a pot excavatedat Dombate reported here. Calibration was performed using the OxCalprogram, version 3.5 (Bronk Ramsey 2000) with atmospheric data fromStuiver et al. (1998)Site Sample no. Years BPCha de Parada 3 Gif-8289 5070 [+ or -] 100Antelas OxA-5498 5070 [+ or -] 65Dombate Avg. of 2 dates 4918 [+ or -] 46Dombate Avg. of 2 dates organic residue 4895 [+ or -] 30Madorras 1 GrN-21066 4790 [+ or -] 60Madorras 1 OxA-5199 4540 [+ or -] 65Cha de Parada 1 CSIC-954 4820 [+ or -] 40Cha de Parada 1 ICEN-173 4610 [+ or -] 45Site Cal BC (2[sigma]) Probability (%)Cha de Parada 3 4050-3600 95.4Antelas 3980-3700 95.4Dombate 3790-3630 95.4Dombate 3715-3635 95.4Madorras 1 3700-3490 79.4 3460-3370 16.0Madorras 1 3500-3430 6.0 3380-3020 89.4Cha de Parada 1 3700-3510 95.4Cha de Parada 1 3550-3300 81.0 3250-3100 14.4 Acknowledgements This research was funded in part by National Science FoundationArchaeometry Grant No. 0209312 and the University of California The University of California has a combined student body of more than 191,000 students, over 1,340,000 living alumni, and a combined systemwide and campus endowment of just over $7.3 billion (8th largest in the United States). Officeof the President/CAMS minigrant program. Additional funding was from aFEDER-CICYT Research Project (Ref. 1FD97-0805-C02-01), co-financed bythe Spanish Ministerio de Ciencia y Tecnologla and European Union funds:Procedimiento Interdisciplinar de caracterizacion, diagnosisyconservacion depintura megalitica. Radiocarbon analyses were performedunder the auspices of the U.S. Department of Energy by the University ofCalifornia Lawrence Livermore National Laboratory Lawrence Livermore National Laboratory:see Lawrence Berkeley National Laboratory. (body) Lawrence Livermore National Laboratory - (LLNL) A research organaisatin operated by the University of California under a contract with the US Department of Energy. (contractW-7405-Eng-48). References ALONSO, F. & J.M. BELLO DIEGUEZ. 1997. Cronologia yperiodizacion del fen6meno megalkico en Galicia a la luz de lasdataciones por C-14, in A. Rodriguez Casal (ed.). O Neolitico Atlatico eas orixes do Megalitismo: 507-20. 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Arqueoloxiada morte na Peninsula Iberica desde as Orixes ata o Medievo: 95-125.Excmo: Concello Xinzo de Limia Xinzo de Limia (elevation 620 metres; population of the concello 9,999 hab; population of the town 6,618 hab. (INE 2006)), is a town in the province of Ourense, Autonomous Community of Galicia, Spain. . HEDGES, R.E.M., C.B. RAMSEY, G.J. VAN KLINKEN, P.B. PETTITT, C.NIELSEN-MARCH, A. ETCHEGOYEN, J.O.F. NIELLO niello(nēĕl`ō)[Ital. from Latin nigellus=blackish], black metallic alloy of sulfur, copper, silver, and usually lead, used as an inlay on engraved metal. , M.T. BOSCHIN & A.M.LLAMAZARES. 1998. Methodological issues in the [sup.14]C dating of rockpaintings. Radiocarbon 40: 35-44. PACE, M.F.N., M. HYMAN, M.W. ROWE & J.R. 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SPURK. 1998.INTCAL98 radiocarbon age calibration, 24000-0 cal BP. Radiocarbon 40:1041-83. VALLADAS, H. & J. CLOTTES. 2003. Style, chauvet andradiocarbon. Antiquity 77: 142-5. VAN DER MERWE, N.J., J. SEALY & R. YATES. 1987. Firstaccelerator carbon-14 date for pigment from a rock painting. SouthAfrican Journal of Science 83: 56-7. Received: 24 November 2003; Accepted: 18 May 2004; Revised: 1 June2004 K.L. Steelman (1), F. Carrera Ramirez (2), R. Fabregas Valcarce(3), T. Guilderson (4) & M.W. Rowe (5) (1) Department of Chemistry, 205 Laney Hall, University of CentralArkansas The University of Central Arkansas is a state-run institution located in the city of Conway, the seat of Faulkner County, north of Little Rock. The school is most respected for its programs in Education, Occupational Therapy, and Physical Therapy. , 201 Donaghey Avenue, Conway, AR 72035, USA (Email:ksteel@uca.edu) (2) Escola Superior de Conservacion e Restauracion de BensCulturais de Galicia, Rua Xeneral Martitegui s/n 36002 Pontevedra, Spain(Email: fernandocarrera@wanadoo.es) (3)Universidade de Santiago de Compostela, Departamento de Historia1, Facultade de Xeografia e Historia, 15782 Santiago de Compostela,Spain (Email: phfaoreg@usc.es) (4) Center for Accelerator Mass Spectrometry, Lawrence LivermoreNational Laboratory, Livermore, CA 94551-9900, USA (Email:guilderson1@popeye.llnl.gov) (5)Department of Chemistry, Texas A&M University, P.O. Box30012, College Station, TX 77842-3012, USA (Email:rowe@mail.chem.tamu.edu)