Radiocarbon dating by the accelerator technique

Radiometric dating of archaeological samples by the accelerator mass spectrometry (AMS) technique is well established today. The main advantage of this method compared to the old decay counting procedure is the small sample size (1 mg carbon equivalent weight) needed to carry out a dating. The basic principles as well as the present status of the technique are presented. Experiences from the first year of routine measurements in the Uppsala laboratory are discussed and some examples of the material analysed are given.     

Radiocarbon dating of bone by accelerator mass spectrometry

A companion article describes the sample preparation method used in the production of graphite targets for the Oxford accelerator mass spectrometer (AMS) system. The chemical pretreatment developed for the dating of bone, ivory and tooth samples is described in this paper.     

Radiocarbon dating: Some practical considerations for the archaeologist

The article is divided into four main sections in each of which a key aspect of radio-carbon dating is discussed with emphasis on the practical implications for users of dates. The four topics which the article attempts to deal with are, in turn, (i) the effect on the radiocarbon timescale of the variations in atmospheric ¹⁴C now known to have occurred in the past and the role of other absorlute dating methods in investigating these, (ii) laboratory measurement of ¹⁴C, (iii) selection of optimum samples for dating and (iv) some of the limitations of the final dates. The theme is essentially that the technical difficulties of radiocarbon measurement in the laboratory have been overcome to the extent that the physical measurements can now be made with high precision, that is to within ±1% or better, as a routine. Thus, it is more important than ever (a) that only reliable samples having very firm associations should be dated and (b) that pretreatment of such samples by the dating laboratory to remove any age contaminants should be completely effective. However, in addition to the recognized statistical limitations, the absolute accuracy of radio-carbon dating is limited by the past ¹⁴C variations. Coupled with the requirements of proper association and pretreatment of samples is the long-term need to establish an overall correlation between radiocarbon and calendar years. At present this is still a matter for final agreement by the laboratories concerned. Meanwhile, when all possible steps have been taken to ensure the reliability of the date messurements, these can strictly only be compared with one another in terms of radiocarbon years bp. In practice this is often too restrictive but any attempts at calibration must be regarded as approximations for the time being. In this article the lower and upper case notation advocated in Antiquity46, 265, for radiocarbon and calendar years respectively has been followed.     

Radiocarbon dating of Ohalo II: Archaeological and methodological implications

Charcoal samples from the Early Epipalaeolithic submerged fisher-hunter-gatherers site of Ohalo II have been dated by three laboratories. The samples derive from huts, hearths, a grave and a stone installation. Twenty-five date range between 17,500-21,050 bp and average c. 19,400 bp. The thickness of deposits, the perishable building material (of the huts), the spatial organization of the camp and its rapid cover by sand and water suggest several occupational episodes, lasting not more than tens of years together. The discrepancy between the range of ¹⁴C dates and the real length of occupation are due to the statistical limitations of the dating method.     

Radiocarbon dating of the bronze age bone pins from Eurasian steppe

Bone catapult and hammer-headed pins played one of very specific roles in funerary offerings in the Bronze Age graves uncovered in the Eurasian Steppes and the North Caucasus. Scholars used different types of pins as key grave offerings for numerous chronological models. For the first time eight pins have been radiocarbon dated. ¹⁴C dating of bone pins identified the catapult type pin as the earliest one. They marked the period of the Yamnaya culture formation. Then Yamnaya population produced hammer-headed pins which became very popular in other cultural environments and spread very quickly across the Steppe and the Caucasus during 2900–2650 cal BC. But according to radiocarbon dating bone pins almost disappeared after 2600 cal BC.     

Radiocarbon dating of prehistoric hearths in alpine northern Sweden: problems and possibilities

The chronology of prehistoric Sami settlement sites has previously been established by conventional radiocarbon dating of bulk charcoal samples associated with hearths from sunken hut floors (stállo-foundations). Here we present results of a comprehensive dating exercise of stállo-foundations in the alpine area of northern Scandinavia using Accelerator Mass Spectrometry (AMS) radiocarbon dating of charcoal. Over a 3 km² study area, AMS calibrated ages of hearth charcoal from 22 stállo-foundations across 12 sites securely date these features to between cal. AD 640 and AD 1180. Only small variations in age were found between charcoal samples from different areas of a given hearth. Statistical analysis of all the charcoal AMS radiocarbon dates obtained reveals that 12 stállo-foundations across nine sites are contemporaneous and date to the Viking Period (AD 800–AD 1050). The tightly constrained AMS-based chronology of stállo-foundations contrasts with the existing chronology based on conventional radiocarbon analysis, which places these features within a significantly greater time-frame of between AD 600 and AD 1900, with most dates ranging between AD 800 and AD 1350.This discrepancy is likely to result from the necessity of collecting composite hearth charcoal particles, which may originate from different phases of occupation, in order to achieve the required final carbon content for conventional radiocarbon analysis. We argue that the new AMS-based radiocarbon chronology of stállo-foundations presented here supersedes the existing chronology based on conventional (Gas Proportional counting) radiocarbon analysis and we advocate the use of AMS radiocarbon dating in future hearth investigations.     

Radiocarbon measurements

In the present series we have dated two samples from a previously unknown pilework E. of the Kastelholm castle, two other logs from old layers to the S. of the castle, two charcoal samples from a layer E. of the castle, four samples of various materials from a ditch SE of the castle, and one sample from outside the NE part of the castle. All the samples were carefully pre‐treated, δ¹³C normalization performed and the measurements extended to reach a statistical uncertainty of usually less than ±60 years. The results are given in radiocarbon years and calibrated.     

陕西志丹县马头山道教真身泥塑年代的测定分析

14C测年技术作为一种测年技术已广泛地应用在考古学、地质年代学、古气候学、古地理学等许多方面。为了解陕西志丹县马头山道教真身泥塑的年代,采用加速器质谱14C技术对道教真身泥塑的谷秸进行了测试,测试结果表明该真身泥塑制作年代在17世纪中叶至18世纪末的可能性较大。     

Radiocarbon pottery dating: the chemical compounds of organic fractions, the reliability of 14C dates (preliminary results)

In recent times, a large number of radiocarbon dates appeared for the Southern Neolithic on the basis of pottery dating because other organic matter has practically not been preserved. There are two organic fractions of pottery useful for dating: food residues and carbon from the pottery matrix itself. Food residues are often dated, but this material is not always preserved and is prone to being removed during the cleaning of the pottery. The clay mass of the pottery contains carbon, often directly visible upon breaking of the pottery. The article focusses on determining the chemical composition of the organic fractions in the pottery and the origin of the carbon. For this aim we used the nuclear magnetic resonance (NMR) method to identify the chemical compounds in the food residue and in the pottery matrix. As an example we used pottery from the Neolithic sites: Zamost??e (Central Russia) and the Varfolomeevskay sites (Southern European Russia, Low Volga region) from archaeological collections. The results obtained demonstrate that the food residue and the pottery matrix contain practically the same organic compounds, even if the relative abundances of various compounds are different in these materials. The origin of the carbon from pottery is discussed.     

Radiocarbon dating of marine shell samples. The marine radiocarbon reservoir effect of coastal waters off Atlantic Iberia during Late Neolithic and Chalcolithic Periods

Radiocarbon dates on marine shells have not been used as extensively as charcoal or bone dates for the setting up of absolute chronologies because interpreting these dates is complicated by the marine radiocarbon reservoir effect. Nevertheless marine shellfish were used widely at least during the Holocene and their shells are abundant and usually well preserved in archaeological deposits located near shorelines. Consequently prior research concerning the oceanographic conditions and the marine radiocarbon reservoir effect of a particular coastal area is needed in order to set up reliable chronologies for that region. Values of regional marine radiocarbon reservoir effect – ΔR – of coastal waters off Atlantic Iberia, some of its variability along the Holocene and its correlation with the upwelling phenomenon were determined during previous research. More data related to the ΔR values for western Portuguese coastal waters during the Late Neolithic and the Chalcolithic, a time interval badly sampled in previous research, were recently obtained. These values can be compared with ΔR values already determined for the Gulf of Cadiz. Besides the importance of these values for a better knowledge of the palaeoceanography and palaeoclimatology of Atlantic Iberia, from now on archaeologists can set up reliable chronologies for Late Neolithic and Chalcolithic contexts using marine shell samples of that origin for radiocarbon dating.     

Radiocarbon Chronology of the Siberian Paleolithic

We have compiled 462 C-14 determinations for 120 Paleolithic and Mesolithic sites from Siberia and the Russian Far East. The Mousterian sites are dated to ca. 46,000–28,500 BP. The Middle–Upper Paleolithic transition dates to ca. 43,300–28,500 BP. Although there are a few earlier sites, most of the Upper Paleolithic sites are dated to the time interval between ca. 34,000 BP and 10,000 BP. The earlier Upper Paleolithic stage is characterized by macroblade technology and is radiocarbon-dated to ca. 34,000–20,000 BP. The earliest microblade technology occurs in the late stage of the Upper Paleolithic, dated to ca. 23,000–20,000 BP, but the majority of microblade sites is dated to ca. 20,000–11,000 BP. The Final Paleolithic (Mesolithic) sites date to ca. 12,000–6000 BP. At ca. 13,000–11,000 BP, the earliest Neolithic appeared in both the Russian Far East (Amur River basin) and the Transbaikal. The Paleolithic–Neolithic transition occurred ca. 13,000–6000 BP.     

Radiocarbon and U-series dating of the endemic deer Praemegaceros cazioti (Depéret) from “Grotta Juntu”, Sardinia

Radiocarbon and U-series methods (²³⁰Th/U and ²³¹Pa/²³⁵U) for absolute age determination have been applied to some fossil samples from Grotta Juntu, in North Eastern Sardinia (Italy). The remains belong to the endemic deer species Praemegaceros cazioti, which is here represented by an almost complete skeleton. The three dating methods lead to concordant ages of about 7500 years BP, indicating that the skeleton was maintained as closed system after burial. Taking into consideration these results, Praemegaceros cazioti from Grotta Juntu is now the youngest representative of this species in Sardinia.     

Radiocarbon Wiggle-Match Dating in the Intertidal Zone

Radiocarbon wiggle-match dating is a technique that can combine the versatility of radiocarbon dating with chronological information from tree-rings. This makes it useful in contexts where timbers are preserved, but dendrochronological dating is impossible. As intertidal and marine timbers are waterlogged, this can favor their preservation and hence allow wiggle-match ¹⁴C dating, which can be of significant help in deriving relatively precise chronologies for a range of coastal structures. As the technique depends on making multiple radiocarbon measurements towards a single date, efficiency in application is the key and hence a number of practical considerations need to be taken into account in advance of conducting a dating program. This paper discusses some of these practical concerns and reviews them in the context of the intertidal crannogs in the Firth of Clyde on the west coast of Scotland.     

Radiocarbon method in monitoring of fossil fuel emission

The traditional radiocarbon method widely used in archaeology and geology for chronological purposes can also be used in environmental studies. Combustion of fossil fuels like coal, natural gas, petroleum, etc., in industrial and/or heavily urbanized areas, has increased the concentration of carbon dioxide in the atmosphere. The addition of fossil carbon caused changes of carbon isotopic composition, in particular, a definite decrease of ¹⁴C concentration in atmospheric CO₂ and other carbon reservoirs (ocean and terrestrial biosphere), known as the Suess effect. Tree rings, leaves, as well as other annual growing plants reflected the changes of radiocarbon concentration in the atmosphere due to processes of photosynthesis and assimilation of carbon from the air. By measuring radiocarbon concentration directly in atmospheric CO₂ samples and/or biospheric material growing in industrial and/or highly urbanized areas where high emission of dead carbon is expected, it is possible to estimate the total emission of dead CO₂. Based on equations of mass balance for CO₂ concentration, stable isotopic composition of carbon and radiocarbon concentration it is possible to calculate CO₂ con-centration associated with fossil fuel emission into the atmosphere. The procedure use differences between the radiocarbon concentration and stable isotope composition of carbon observed in clean areas and industrial or/and highly urbanized areas.     

Thermoluminescence dating

Over the last few years the Nordic Laboratory for Thermoluminescence (TL) Dating has obtained TL dates for a considerable number of archaeological samples, ceramics, bricks, burnt clay and burnt stones from the Nordic countries. The majority of TL dates have been consistent and in agreement with other dating evidence. Discrepancies caused primarily by excessive short‐term fading of the latent TL signal were encountered in a few cases. A procedure for eliminating errors caused by short‐term fading is described. A brief discussion of the sources of error in TL dating is given. Finally, results obtained by TL are compared with those obtained by radiocarbon for a number of sites.     

Radiocarbon Dates from the Loughcrew Cairn h Bone Slips

A total of 150 intricately carved bone slips were uncovered at the Loughcrew H passage tomb in Co. Meath, Ireland, during excavations between 1865 and 1943. Studies of the carvings identified La Tène motifs suggesting that the slips may have been Middle to Late Iron Age in date. Joseph Raftery even went so far as to argue that the megalithic tomb itself was an Iron Age construction. His theory has since been debunked, but absolute dates have not been forthcoming for either these finds or the tomb. The following Middle Iron Age results presented here are slightly earlier than the dates that had hitherto been anticipated and they help to shed light on the subsequent interactions with this tomb.     

Radiocarbon evidence indicates that migrants introduced farming to Britain

Archaeologists disagree about how farming began in Britain. Some argue it was a result of indigenous groups adopting domesticates and cultigens via trade and exchange. Others contend it was the consequence of a migration of farmers from mainland Europe. To shed light on this debate, we used radiocarbon dates to estimate changes in population density between 8000 and 4000 cal BP. We found evidence for a marked and rapid increase in population density coincident with the appearance of cultigens around 6000 cal BP. We also found evidence that this increase occurred first in southern England and shortly afterwards in central Scotland. These findings are best explained by groups of farmers from the Continent independently colonizing England and Scotland, and therefore strongly support the migrant farmers hypothesis.