Complex interdisciplinary studies carried out in the territory of the Vilnius Lower Castle, E Lithuania, were used to construct a chronological framework based on radiocarbon data and archaeological information. Bulk samples (wood and sediment) were collected from an approximately 3-m core that crossed cultural layers and underlying strata. 14C dates indicate that the underlying bed possibly formed during the 6th century AD, although no archaeological finds were discovered there. Paleobotanical (pollen and plant macrofossil) investigations reveal evidence of agriculture that points to the existence of a permanent settlement in the area at that time. The chronological data indicates a sedimentation hiatus before the onset of the deposition of the cultural layer in the studied area. The 14C dates showed that the formation of the cultural bed began during the late 13th–early 14th centuries AD, that is, earlier than expected according to the archaeological record. The ongoing deposition of the cultural beds continued throughout the middle to latter half of the 14th century AD as revealed by the archaeological records and confirmed by well-correlated 14C results. After some decline in human activity in the middle of the 14th century AD, a subsequent ongoing development of the open landscape, along with intensive agriculture, points to an increase in human activity during the second half of the 14th century AD. The first half of the 15th century AD was marked by intensive exploitation of the territory, indicating a period of economic and cultural prosperity. The chronological framework indicates that the investigated cultural beds continued forming until the first half of the 16th century AD.

Chronological and stratigraphic frameworks are of the utmost importance for Upper Paleolithic archaeology, physical anthropology, and ecology. Wide ranging radiocarbon (14C) dates were previously obtained for the Sungir burial complex in the central part of European Russia, which is well-known as the richest funeral Paleolithic assemblage in the world yet recorded. The major problem was the contamination caused by consolidants used during the recovery of human bones in the 1960s. The stratigraphy and spatial structure of the Sungir site were also not well understood previously. New radiocarbon and stable isotope data are generated for the Sungir burials. While some dates were younger due to incomplete removal of contamination, the XAD 14C age on S-1 burial (ca. 29,780 BP) was found to be statistically the same as the previously performed HYP 14C age for this burial (ca. 28,890 BP). Four animal bones found in cultural layer below the burial date to ca. 28,800–30,140 BP, suggesting that both this layer and human burials date to roughly this age range. Narrowing these ages further is difficult considering the larger errors of the 14C dates. This shows that future research attempting to 14C date material excavated many years ago needs to eliminate potential contamination from consolidants through analyses such as FTIR, prior to 14C dating. The chronology and stratigraphy of Sungir do not contradict to correlation of its lithic artifacts with the Streletskian assemblage as the East European variant of the Final Szeletian technocomplex (Early Upper Paleolithic).

The development of chronologies relies on integrating information from a number of different sources. In addition to direct dating evidence, such as radiocarbon dates, researchers will have contextual information which might be an environmental sequence or the context in an archaeological site. This information can be combined through Bayesian or other types of age-model. Once a chronology has been developed, this information can be used to estimate, for example, chronological uncertainties, rates of change, or the age of material which has not been directly dated.

Dealing with the information associated with chronology building is complicated and re-evaluation of chronologies often requires structured information which is hard to access. Although there are many databases with primary dating information, these often do not contain all of the information needed for a chronology. The Chronological Query Language (CQL) developed for OxCal was intended to be a convenient way of pulling such information together for Bayesian analysis. However, even this does not include much of the associated information required for reusing data in other analyses.

The IntChron initiative builds on the framework set up for the INTIMATE (Integrating Ice core, Marine and Terrestrial Records) chronological database (Bronk Ramsey et al. 2014) and is primarily an information exchange format and data visualization tool which enables users to pull together the types of information needed for chronological analysis. It is intended for use with multiple dating methodologies and while it will be integrated with OxCal, is intended to be an open format suitable for use with other software tools. The file format is JSON which is easily readable in software such as R, Python and MatLab. IntChron is not primarily intended to be a data depository but rather an index of sites where information is stored in the relevant format. As an initial step, databases of radiocarbon dates from the Oxford Radiocarbon Accelerator Unit (including those for the NERC radiocarbon facility), the RESET tephra database, the INTIMATE chronological database and regional radiocarbon databases for Egypt and Southern Africa are all linked. The intention is that users of OxCal will also be able to make published data accessible to others and to store working data, visible only to the user, to be used with the associated analysis tools. The IntChron site allows data from third party sources to be accessed through a representational state transfer (REST) application programming interface (API) in a number of different formats (JSON, csv, txt, oxcal) and associated bibliographic information in BibTeX format.

The aim of the IntChron initiative is to make it easy for users to provide data (in the single JSON format with limited minimum requirements) as well as to access data and tools, while promoting robust chronologies including realistic estimates of uncertainties. It is hoped that this will help to bring the chronological research communities to a point where data access is as easy as it is in some other fields. This is particularly important for Early Career Researchers and for those seeking to use large datasets in novel ways.

The San Pedro de Atacama oases, located in northern Chile’s hyperarid Atacama Desert, have been occupied for at least 3000 years. Here, we examine cemetery use in the oases, with emphasis on the Middle Period (ca. AD 400–1000). By modeling of a large corpus (n=243) of radiocarbon dates, over 90% of which are direct AMS assays of human bone collagen, we attempt to establish a temporal framework by which to explore the establishment of formalized social inequality in this period. Modeling of these dates at three locally defined scales (all ayllus, inter-ayllu, and intra-ayllu) permit heretofore unavailable insights into the chronological and spatial dimensions of life and mortuary activity in the oases and allow us to better contextualize patterns of social inequality during the dynamic Middle Period. The results of this modeling indicate two distinct peaks of occupation during the Middle Period in San Pedro and document significant temporal variability in cemetery use patterns on both inter- and intra-ayllu scales. These results stress the importance of local social and environmental factors to the occupation of the oases and provide crucial chronological structure for future archaeological and bioarchaeological research in the region.

The following list comprises measurements made since those reported in NPL III and is complete to the end of November 1965.

Ages are relative to A.D. 1950 and are calculated using a half-life of 5568 yr. The measurements, corrected for fractionation (quoted δC13 values are relative to the P.D.B. standard), are referred to 0.950 times the activity of the NBS oxalic acid as contemporary reference standard. The quoted uncertainty is one standard deviation derived from a proper combination of the parameter variances as described in detail in NPL III. These variances are those of the standard and background measurements over a rolling twenty week period, of the sample δC14 and δC13 measurements and of the de Vries effect (assumed to add an additional uncertainty equivalent to a standard deviation of 80 yr). Any uncertainty in the half-life has been excluded so that relative C14 ages may be correctly compared. Absolute age assessments, however, should be made using the accepted best value for the half-life and the appropriate uncertainty then included. If the net sample count rate is less than 4 times the standard error of the difference between the sample and background count rates, a lower limit to the age is reported corresponding to a net sample count rate of 4 times the standard error of this difference.

Bayesian sequencing of radiocarbon dates deals with the problem that in most cases there does not exist an unambiguous way to define the so-called prior function, which represents information in addition to the result of the 14C measurements alone. However, a random choice of a particular prior function can lead to biased results. In this paper, “robust Bayesian analysis,” which uses a whole set of prior functions, is introduced as a more reliable method. The most important aspects of the mathematical foundation and of the practical realization of the method are described. As a general result, robust Bayesian analysis leads to higher accuracy, but paid for with reduced precision. Our investigations indicate that it seems possible to establish robust analysis for practical applications.

In this paper, first results comparing modified Longin and ninhydrin collagen extraction methodologies are presented. The goal of this study is to investigate the bones of several species with different ages, preservation conditions, and collagen contents to determine the most suitable preparation method. Different types of samples are used such as VIRI samples, previously dated bones, and background samples. Each bone has undergone elemental analysis, infrared analysis, and 14C measurement. The results are presented and the advantages and disadvantages of each preparation method are discussed. In general, results obtained by the two methods are in accordance with the consensus value for 2σ uncertainty. For VIRI I and a mammoth bone, the ninhydrin preparation gives, respectively, 8450±70 BP and 14,870±60 BP whereas the modified Longin process gives 8365±45 BP and 14,750±100 BP in agreement with the expected values. From the experimental point of view, the modified Longin process is easier to implement than the ninhydrin protocol. From this approach, we can conclude that the modified Longin process could be preferred in most cases and particularly when the amount of bone is small and the sample is not too contaminated.

The Nevado de Toluca is a stratovolcano located in the southwest of the Toluca Valley in central Mexico. At a height of around 4200 m there are two crater lakes: El Sol and La Luna. Since Precolumbian times, people in the surrounding valleys carried out rituals and deposited offerings into the lakes. After the Spanish conquest, these rituals were kept alive clandestinely. Currently, reminiscent of Mesoamerican rituals subsist. Due to the long duration of the ritual at the Nevado de Toluca, it is important to date the materials recovered in the underwater and terrestrial archaeological explorations. This article proposes a chronology of Prehispanic ritual activities performed in the Nevado de Toluca based on the characterization and radiocarbon (14C) dating performed to materials from the volcano’s lakes.

The dating equipment and operating conditions remain essentially as previously described. All samples are from Ireland unless specified.

In order to verify sediment trap samples as indicators of upper ocean 14C concentrations, particulate inorganic radiocarbon (PICΔ14C) collected by time-series sediment traps in the Sea of Okhotsk and the Bering Sea was measured by accelerator mass spectrometry (AMS). All of the PICΔ14C measurements were < 0‰, in contrast to GEOSECS 14C data in the upper ocean from the northwestern North Pacific. This difference is attributed to the upwelling of deepwater that contains low Δ14C of dissolved inorganic carbon (DICΔ14C) and to the decrease over time of surface DICΔ14C owing to the decrease of atmospheric Δ14C values. In addition, PICΔ14C values showed significant seasonal variability: PICΔ14C collected in the fall was the greatest (-22‰ on average), whereas PICΔ14C collected in winter showed an average minimum of −48‰. It is likely that this difference was caused by changes in mixed layer thickness. Although some uncertainties remain, further study on PICΔ14C will enable us to estimate seasonal variability in DICΔ14C and air-sea CO2 exchange rate.

A fast 14C sample preparation technique for organic material in conventional 14C counting is described. The basic difference from conventional preparation is oxidation of the organic substances in a closed system under an oxygen pressure of ca 10 bars. After the explosion-like combustion, the reaction products SO2 and NO2 are oxidized immediately to SO4 2-and NO3 − and precipitated on the wall of the reaction vessel. The residual gas mixture is passed first through a cold trap at −78° to remove water vapor and then through an activated charcoal column at 0° for purification. CO2 is removed from the remaining O2−CO2 gas mixture in a LN2 trap at a pressure of ≃ 100mbar. With this method sample preparation time is reduced from ca 10 hr to ca 1 hr. The efficiency and reproducibility of the procedure is shown with 14C and 13C measurements of a sugar-carbon standard. The results obtained by the new technique agree well with conventionally prepared wood and bone samples.

This date list includes most of the archaeologic and geologic samples dated in this laboratory since publication of our last date list (R, 1981, v 23, p 227–240), as well as some samples dated previously which lacked adequate sample information.

All samples were pretreated with 3N HCl and some, where noted, were given additional pretreatment with 2% NaOH for the removal of possible humic acid contaminants.

We have studied the application of carbonates and organic matter to the radiocarbon dating of a paleolake. The results show a systematic apparent age shift of these materials with respect to contemporary wood. The apparent age of carbonates is evidently due to the hard-water effect, whereas the apparent age of organic matter, systematically younger than carbonates, is attributed to aquatic plants, which metabolize dissolved CO2. Terrestrial plants that deposit organic matter also cause apparent age discrepancies between carbonates and organic matter.

This list describes samples dated in this laboratory between November 1972 and December 1974.

Previous results from remains of tusks, teeth and bones collected from Wrangel Island (Vartanyan et al. 1995) had given results in the range 3730 bp to 20,000 bp and the authors had concluded that “mammoths inhabited Wrangel Island for as long as 6000 yr after the estimated extinction on the Siberian continent”. There still remained the question of the earliest date for such remains. Further, the authors had noted such samples may present some difficulty in dating and therefore duplicate samples had been measured in a second laboratory with satisfactory results. The replicate dating of important or controversial samples in more than one laboratory is well-established (e.g., Turin Shroud) and in this paper, we present results for 5 mammoth samples dated by 6 laboratories. Such interlaboratory comparisons provide an independent means of verification of laboratory comparability, and give added confidence in the results, particularly when applied to more controversial samples. A further objective of the work has been to evaluate the material for inclusion in any large-scale interlaboratory comparison, such comparisons having in the past formed part of laboratory quality assurance protocols. The design and organization of a laboratory intercomparison requires homogeneous samples in sufficient quantity to satisfy participants, and so in principle, a single mammoth tusk would meet these criteria. Samples such as the mammoth tusk have been used in previous intercomparisons: e.g., in the last large-scale international intercomparison (Gulliksen and Scott 1995), whalebone was one of the materials distributed. One of the key advantages of such material is that a single sample (a mammoth tusk) can be resampled for analysis by multiple labs and thus does not require bulk homogenization. Therefore, as part of a preselection process for a future intercomparison, five samples from separate mammoth tusks were collected from Wrangel Island in 1995 in sufficient quantity to allow multiple dating. The aim was to identify five separate samples of young age, sample up to 1 kg from each tusk and mark the location so that after preliminary dating, samples could be retrieved as required in the future. Six laboratories received samples for dating. The paper will discuss the results from the laboratories, present consensus values, and make recommendations concerning use of these samples in a future laboratory intercomparison.

The radiocarbon variation for northwestern Mexico during the period 1950–2004 was studied by accelerator mass spectrometry (AMS) and liquid scintillation counting (LSC) analyses of tree rings. Two tree-ring sequences of Pseudotsuga menziesii, sampled in a site isolated from urban centers and active volcanoes (26.18°N, 106.3°W, 3000 m asl), were dendrochronologically dated and separated in annual rings prior to 14C analysis. Results obtained show a similar profile to the values reported for the Northern Hemisphere (NH), having significant correlation coefficients with the compilation curves for NH zone 2 (r = 0.987, p < 0.001) and NH zone 3 (r = 0.993, p < 0.001). The maximum peak is centered at 1964.5 with a δ14C value of 713.15 ± 9.3‰. The values obtained for the period 1958–1965 are lower than zone 2 values and higher than zone 3 values. For the period 1975–2004, the values obtained are higher than the NH compilation curve and other NH records. We attribute the first divergence to the North American monsoon that may have carried 14C-depleted air from the south during the summer months; the second divergence may be attributable to 14C-enriched biospheric CO2.

Estimation of the magmatic contribution to soil air at Unzen Volcano, SW Japan, was carried out using carbon isotopes, both 14C and 13C, and a mixing model of isotopic mass balance in order to assess the spatial variation of magmatic influence from the volcano. The advantage of using soil air samples is that a wide range of gas sampling sites can be selected. Magmatic CO2 contributed mostly in the eastern region from Unzen Volcano. The high magmatic contribution to soil air appeared along the Akamatsudani fault zone located southeast of the volcano. Our observations across the fault also showed remarkable peaks of CO2 concentration and δ13C values, suggesting that magmatic fluid comes up along the fracture zone as for the normal fault system of the graben.

A case study of the Neolithic comb ceramic site Pezmog 4 of the Kama culture presents a situation when results of radiocarbon dating change long-existing concepts concerning the development of archaeological events. Until the early 2000s, the chronology of the Kama culture, distributed mainly in the Kama and Vychegda River basins, has been based on comparative-typological analysis. Estimates of the age of this culture changed from the 3rd millennium BC in the 1950s to the 1st half of the 4th millennium BC by the 1990s. Research concerning the Pezmog 4 site in the central Vychegda River basin in 1999–2002 has abruptly changed this chronological understanding. The data obtained put the age of the early stage of Kama culture within the time range 5750–5620 cal BC and allowed us to propose the existence of another way of early pottery distribution in the forest zone of eastern Europe at the beginning of the 6th millennium BC. This innovation probably penetrated from the trans-Ural region.

The Laschamp excursion is a period of reduced geomagnetic field intensity occurring 40.7 ± 1.0 kyr ago. As a consequence, cosmogenic isotope production increased dramatically and its sensitivity to solar activity was enhanced during this period. The latter occurs because a larger fraction of the lower-energy interstellar galactic cosmic-ray particles, normally excluded by the geomagnetic field, is able to reach Earth's atmosphere. This produces a cosmogenic isotope production signal with a significant structure. As high-resolution 10Be profiles from both Antarctica (EDC) and Greenland (NGRIP-GRIP) during this crucial period are now available, one can use them as input into a box carbon cycle model in order to predict atmospheric 14C variations due to the Laschamp excursion. For this purpose, 10Be data are converted into 14C, using production calculations for the 10Be-14C conversion, after correction for the estimated difference of sensitivity between polar and global 10Be deposition. Several scenarios of carbon cycle state are simulated, from preindustrial to glacial conditions. Applying two recent cosmogenic isotope production calculations for the 10Be to 14C conversion, we found that the resulting atmospheric Δ14C variations are very sensitive to which of these two are employed. For example, Δ14C amplitude under glacial conditions varies from 260‰ (EDC) and 320‰ (Greenland) to 430‰ (EDC) and 510‰ (Greenland) depending on the formulation used for 10Be-14C conversion.

Two independent programs have collected and analyzed atmospheric CO2 samples from Point Barrow, Alaska, for radiocarbon content (Δ14C) over the period 2003–2007. In one program, flask collection, stable isotope analysis, and CO2 extraction are performed by the Scripps Institution of Oceanography's CO2 Program and CO2 is graphitized and measured by accelerator mass spectrometry (AMS) at Lawrence Livermore National Laboratory. In the other program, the University of California, Irvine, performs flask collection, sample preparation, and AMS. Over 22 common sample dates spanning 5 yr, differences in measured Δ14C are consistent with the reported uncertainties and there is no significant bias between the programs.