. (2015) Best practice methodology for 14C calibration of marine and mixed terrestrial/marine samples. Quaternary Geochronology, 27, pp. 164-171. Copyright © 2015 Elsevier B.V.A copy can be downloaded for personal non-commercial research or study, without prior permission or charge Content must not be changed in any way or reproduced in any format or medium without the formal permission of the copyright holder(s) This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. Abstract: There is a lack of detailed guidance in the published literature on how to calibrate 14 C measurements made on marine or mixed marine/terrestrial (primarily human remains) samples. We describe what we consider to be the best approach towards achieving the most accurate calibrated age ranges, using the most appropriate ΔR and percentage marine diet estimates, and associated, realistic error terms on these values. However, this approach will increase the calibrated age range(s) by fully accounting for the variability in both the model and the material. While the discussion is based on examples from the UK and Iceland, the same fundamental arguments can be applied in any geographic location largely devoid of C 4 plants as the high δ AbstractThere is a lack of detailed guidance in the published literature on how to calibrate 14 C measurements made on marine or mixed marine/terrestrial (primarily human remains) samples. We describe what we consider to be the best approach towards achieving the most accurate calibrated age ranges, using the most appropriate ∆R and percentage marine diet estimates, and associated, realistic error terms on these values. However, this approach will increase the calibrated age range(s) by fully accounting for the variability in both the model and the material. While the discussion is based on examples from the UK and Iceland, the same fundamental arguments can be applied in any geographic location largely devoid of C 4 plants as the high δ 13C values from such plants can make identification of marine intake difficult to determine.

We review the history of Bayesian chronological modeling in archaeology and demonstrate that there has been a surge over the past several years in American archaeological applications. Most of these applications have been performed by archaeologists that are self-taught in this method because formal training opportunities in Bayesian chronological modeling are infrequently provided. We define and address misconceptions about Bayesian chronological modeling that we have encountered in conversations with colleagues and in anonymous reviews, some of which has been expressed in the published literature. Objectivity and scientific rigor is inherent in the Bayesian chronological modeling process. Each stage of this process is described in detail and we present examples of this process in practice. Our concluding discussion focuses on the potential Bayesian chronological modeling has for enhancing understandings of important topics. 3 SPANISH ABSTRACTEn este artículo se revisará la historia de la modelización cronológica Bayesiana en arqueología y se mostrará cómo la arqueología americana ha experimentado en los últimos años un auge en su aplicación. La mayor parte de los análisis han sido desarrollados por arqueólogos que han sido autodidactas en el aprendizaje del método, ya que las oportunidades de formación en el análisis Bayesiano son muy limitadas. Se explicarán cuáles son los errores más comunes en la aplicación de la modelización cronológica Bayesiana con los que nos hemos encontrado al conversar con compañeros, así como en revisiones anónimas, algunas de los cuales ya han sido señaladas en otros trabajos. La objetividad y el rigor científico resultan inherentes al proceso de modelización cronológica Bayesiana. Se describirá en detalle cada etapa de este proceso, presentando ejemplos de su puesta en práctica. Nuestra conclusión se centrará en torno al potencial de este método para mejorar nuestra comprensión sobre temas de gran relevancia.

Archaeological investigations in the Iron Gates reach of the Lower Danube Valley between 1964 and 1984 revealed an important concentration of Stone Age sites, which together provide the most detailed record of Mesolithic and Early Neolithic settlement from any area of southeastern Europe. Over 425 human burials were excavated from 15 sites. Of these, less than one-fifth have been directly dated. This article presents 37 new AMS dates on human bone from five sites in the Iron Gates, together with the corresponding δ 13 C and δ 15 N values. They include the first dates on human bone from two sites, Icoana and Velesnica. The results are important for the chronology of Stone Age mortuary practices in the Iron Gates and the timing of the Mesolithic-Neolithic transition in the region.

Obtaining chronological control for geomorphological sequences can be problematic due to the fragmentary and non-sequential nature of sediment and landform archives. The robust analysis of 14 C ages is often critical for the interpretation of these complicated sequences. This paper demonstrates a robust methodology for the 14 C dating of geomorphological sequences using a case study from the lower Ribble valley, northwest England. The approach adopted incorporates using greater numbers of ages, targeting plant macrofossils, obtaining replicate measurements from single horizons to assess the extent of reworking and the use of Bayesian approaches to test models of the relative order of events. The extent of reworking of organic materials and space-time dynamics of fluvial change means that it is critical that chronological control is sufficiently resourced with 14 C measurements. As a result Bayesian approaches are increasingly important for the evaluation of large data sets. Assessing the conformability of relative order models informed by interpretation of the geomorphology can identify contexts or materials that are out of sequence, and focuses attention on problem materials (reworking) and errors in interpretation (outlier ages). These relative order models provide a framework for the interrogation of sequences and a means for securing probability-based age estimates for events that occur between dated contexts. This approach has potential value in constraining the sequence of geomorphological development at scales that vary from individual sites to a catchment or region, furthering understanding of forcing and change in geomorphological systems. Figure 4. Landform and depositional contexts used for 14 C dating of geomorphological changes recorded in alluvial units (after Lewin et al., 2005; Chiverrell et al., 2008). RADIOCARBON DATING LANDFORM DEVELOPMENT IN FLUVIAL ENVIRONMENTS 325 Figure 6. Three different chronological models, (a), (c) and (d) for Lower House are used to estimate the age of the 'Geomorphological change', which equates to the switch from terrace T3 to T4 The large square brackets on the left along with the OxCal keywords define the model. A question mark (?) indicates that a result has been excluded from the model. (b) A schematic representation of the structure for Sequences models, with Sequences comprise dating information arranged in an expected order (oldest first) and that one event precedes another is incorporated into the resultant probability distributions. Phases are groups of ages for which no information is assumed about their relative ages but they share similar relationships with other items in the sequence model. Probability distributions have been estimated for features (Geomorphological change) that have not been specifically 14 C dated by placing Date queries within the sequence of 14 C ages. Details of the Markov Chain Monte Carlo sampling and the algorithms employed in Oxcal for this are available from the on-line manual (http://c14.arch.ox.ac.uk/oxcal.html) and in Bronk ...

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Radiocarbon dating was long neglected in Iron Age research, with dates on the 'Hallstatt plateau' (800-400 BC) considered too broad to be useful compared to artefact typo-chronologies. Such views are now untenable. Around fifty British Iron Age settlements and cemeteries have been dated using Bayesian methodologies, yielding two important general results: (1) typological dating produces sequences that are regularly too late; and (2) many phenomena, from chariot burials to settlement shifts, represent brief horizons, rather than being long lived. Drawing on a selection of studies, this article explores the impact of Bayesian modelling on British Iron Age studies. It highlights potential pitfalls and issues that must be considered when dating the period, illustrates some major successes and looks to the future.

The great site of Valencina de la Concepción, near Seville in the lower Guadalquivir valley of southwest Spain, is presented in the context of debate about the nature of Copper Age society in southern Iberia as a whole. Many aspects of the layout, use, character and development of Valencina remain unclear, just as there are major unresolved questions about the kind of society represented there and in southern Iberia, from the late fourth to the late third millennium cal BC. This paper discusses 178 radiocarbon dates, from 17 excavated sectors within the c. 450 ha site, making it the best dated in later Iberian prehistory as a whole. Dates are modelled in a Bayesian statistical framework. The resulting formal date estimates provide the basis for both a new epistemological approach to the site and a much more detailed narrative of its development than previously available. Beginning in the 32nd century cal BC, a long-lasting tradition of simple, mainly collective and often successive burial was established at the site. Mud-vaulted tholoi appear to belong to the 29th or 28th centuries cal BC; large stone-vaulted tholoi such as La Pastora appear to date later in the sequence. There is plenty of evidence for a wide range of other activity, but no clear sign of permanent, large-scale residence or public buildings or spaces. Results in general support a model of increasingly competitive but ultimately unstable social relations, through various phases of emergence, social competition, display and hierarchisation, and eventual decline, over a period of c. 900 years.Electronic supplementary materialThe online version of this article (10.1007/s10963-018-9114-2) contains supplementary material, which is available to authorized users.

Rationale:The use of multi-isotopic analysis (δ 15 N, δ 13 C and δ 34 S values) of archaeological bone collagen to assist in the interpretation of diet, movement and mobility of prehistoric populations is gradually increasing, yet many researchers have traditionally avoided investigating sulphur due to its very low concentrations (<0.3%) in mammalian collagen. For this reason, and as a consequence of analytical detection limits, sulphur is usually measured separately from carbon and nitrogen, which leads to longer analytical times and higher costs. Methods:A Thermo Scientific™ EA IsoLink™ isotope ratio mass spectrometry (IRMS) system, with the ability to rapidly heat a gas chromatography (GC) column and concentrate the sample gas online without cryo-trapping, was used at the Radiocarbon Laboratory at the Scottish Universities Environmental Research Centre (SUERC). Optimisation of the GC temperature and carrier gas flow rate in the elemental analyser resulted in improved signal-to-noise (S/N) ratio and sensitivity for SO 2 . This allowed for routine sequential N 2 , CO 2 and SO 2 measurements on small samples of bone collagen.Results: Improvements in sample gas transfer to the mass spectrometer allows for sequential δ 15 N, δ 13 C and δ 34 S values to be measured in 1-1.5 mg samples of bone collagen. Moreover, the sensitivity and S/N ratio of the sample gas, especially SO 2 , is improved, resulting in precisions of ±0.15‰ for δ 15 N values, ±0.1‰ for δ 13 C values and ±0.3‰ for δ 34 S values. Previous instrumentation allowed for the analysis of~30 unknown samples before undertaking maintenance; however, 150 unknown samples can now be measured, meaning a 5-fold increase in sample throughput. Conclusions:The ability to sequentially measure δ 15 N, δ 13 C and δ 34 S values rapidly in archaeological bone collagen is an attractive option to researchers who want to build larger, more succinct datasets for their sites of interest, at a much-reduced analytical cost and without destroying larger quantities of archaeological material.