The emergence of hilltop settlements presents a pattern of the first enclosed sites that reflect economic development in several regions within the Southeastern Baltic Bronze Age. This novelty reflects increasing social complexity, differentiating economic relations, as well as rising tension in the region. The phenomenon has received a great deal of interpretation, but chronological problems still remain understudied. Researchers tend to seek the start of hilltop settling practice from early to late II millennium BC. This paper presents 14C dates from 7 sites in inland Lithuania, where hitherto no absolute dates were published. The majority of absolute dates has been calibrated to the Hallstatt radiocarbon calibration plateau (ca. 800–400 cal BC) which is significantly later than previously presumed based on dates from Belarusian sites. However, several dates from previously dated hilltop settlements in the region predate the effect. These results indicate the start of hilltop settling practice around 11th–9th centuries cal BC. Review of new and previously published radiocarbon dates suggests a different internal development between SE Baltic coastal and inland regions, likely locating zones, where economic outside stimulus preconditioning emergence of hilltop settlements occurred earlier.

The radiocarbon (14C) calibration curve so far contains annually resolved data only for a short period of time. With accelerator mass spectrometry (AMS) matching the precision of decay counting, it is now possible to efficiently produce large datasets of annual resolution for calibration purposes using small amounts of wood. The radiocarbon intercomparison on single-year tree-ring samples presented here is the first to investigate specifically possible offsets between AMS laboratories at high precision. The results show that AMS laboratories are capable of measuring samples of Holocene age with an accuracy and precision that is comparable or even goes beyond what is possible with decay counting, even though they require a thousand times less wood. It also shows that not all AMS laboratories always produce results that are consistent with their stated uncertainties. The long-term benefits of studies of this kind are more accurate radiocarbon measurements with, in the future, better quantified uncertainties.

The monastery of St. John in Müstair, a UNESCO world heritage site, preserves archaeological remains and stone structures dated from the 8th century to the present. It has been extensively studied archaeologically so that numerous samples of historical materials, including mortar, are available for study. In addition to that, some of the structures have been precisely dated with dendrochronology. The monastery is located in a region characterized by dolomite rocks and the mortars are therefore of dolomitic nature, being perfectly suited to test the possibility of being dated with 14C. Furthermore, the presence of embedded carbon fragments has provided additional independent data to support or deny the results of mortar dating. A comparison of the results obtained from radiocarbon (14C) dating of bulk mortars, sieved fractions enriched in binder, lime lumps and carbon fragments, for two samples is presented, in relation to the petrographic characterization and the mineralogical phase content. This preliminary study shows that the dating of 14C can potentially be applied to the mortar of Müstair, as results in accordance with the established chronologies have been obtained for one sample. However, if the dolomitic sand contamination is very high, further studies are needed to develop a specific sample preparation technique.

Holocene climate change in the South Pacific is of major interest to archaeologists and Quaternary researchers. Regional surface ocean radiocarbon (14C) values are an established proxy for studying changing oceanographic and climatic conditions. Unfortunately, radiocarbon variability in the marine environment over the period of specific importance to human colonization of the remote Pacific islands—the last 3500 years—has been poorly studied. In order to build robust and accurate archaeological chronologies using shell, it is important to rectify this. In this paper, radiocarbon marine reservoir offsets (ΔR) are presented from eight archaeological sites, ranging in age from 350 cal BP to 3000 cal BP, and compared to coral datasets from the east Australian coastline. The results indicate that a significant decrease in the South Pacific Gyre ΔR occurred between 2600 and 2250 cal BP, most likely caused by changes in ocean circulation and climate. Accurately recording the timing of variability in reservoir offset is critical to untangling changes in society that took place in the Pacific, in particular, the development of Ancestral Polynesian Society.

At the close of the Bronze Age, a tendency developed in Central Europe towards the concentration of settlement and fortification of sites which served special economic and social functions. One of the largest centers of this kind in the northern part of Central Europe is the Łubowice stronghold (SW Poland). Archaeological excavations allowed the stratigraphy of the fortification remnants to be comprehensively investigated. In their final stage, these fortifications comprised of a monumental earthen rampart with timber structures, which were later destroyed in a violent fire. Originally, the destruction of the Łubowice stronghold was linked with the raids by nomadic Scythians and dated to the first half of the 6th century BC. However, radiocarbon analyses of charcoal from the burned rampart relics have shown that the destruction of the fortifications took place in the 9th century BC. The new dating of the moment when the Łubowice fortifications was burned down, i.e. “shortly after 845–802 cal BC” places this event within historical processes which reshaped the cultural picture in much of Central Europe at the dawn of the Iron Age. The spreading of a new, Hallstatt cultural model was associated with deep changes in social structures.

As the worldwide standard for radiocarbon (14C) dating over the past ca. 50,000 years, the International Calibration Curve (IntCal) is continuously improving towards higher resolution and replication. Tree-ring-based 14C measurements provide absolute dating throughout most of the Holocene, although high-precision data are limited for the Younger Dryas interval and farther back in time. Here, we describe the dendrochronological characteristics of 1448 new 14C dates, between ~11,950 and 13,160 cal BP, from 13 pines that were growing in Switzerland. Significantly enhancing the ongoing IntCal update (IntCal20), this Late Glacial (LG) compilation contains more annually precise 14C dates than any other contribution during any other period of time. Thus, our results now provide unique geochronological dating into the Younger Dryas, a pivotal period of climate and environmental change at the transition from LG into Early Holocene conditions.

Experimental studies have shown that significant carbon exchange occurs between bone-apatite and the pyre atmosphere during cremation, which can cause a calendar date offset between the radiocarbon (14C) event and the date of cremation. There are limited empirical data available to assess the magnitude of such wood-age offsets, but the aim of this paper is to test if they can be modeled statistically. We present new 14C dates on modern bone cremated in realistic open-air experiments and on archaeological samples of cremated bone and associated organic material. Experimental results demonstrate a wide range of carbon exchange with a mean of 58.6 ± 14.8%. Archaeological results indicate that the wood-age offsets have an approximately exponential distribution. We test whether the default Charcoal Outlier_Model in OxCal v4.3, developed to reduce the impact of wood-age offsets in dates of charcoal, is appropriate for cremated bone, but find that it slightly underestimates apparent offsets. To counter the intrinsic age of both pyre fuel and unburned bio-apatite, we instead propose a bespoke Cremation Outlier_Model, which combines an exponential distribution of calendar age offsets with a minimum offset, and provides better estimates of the actual dates of cremations.

Discovered at the beginning of the twentieth century, the Abri Casserole (Dordogne, France) was the subject of salvage excavations in the early nineties. The fieldwork revealed a sequence of 13 archaeological levels that document human occupations from the Gravettian to the Magdalenian, including very rare and poorly known assemblages (e.g. Early Badegoulian, Protosolutrean) that afford a particular importance to this sequence. Results of a previous dating program that focused on the Badegoulian levels were obtained in 1994 but were neither extensively published nor discussed. Five AMS 14C ages obtained for the Gravettian and Solutrean assemblages in the early 2010s served to complement the site’s chronology. However, since the beta counting ages for the Badegoulian levels were in conflict with the accepted AMS chronology for the region’s late Pleniglacial archaeological record, a new AMS dating program was implemented to renew the radiometric framework of this specific portion of the sequence. Compared to the previous beta counting measurements, the seven newly obtained AMS ages are about 1000 years older (23.3–20.5 cal ka BP) and congruent with other AMS-dated Badegoulian sequences. These results thereby restore the inter-site chronological coherence of the Solutrean–Badegoulian and Badegoulian–Magdalenian transitions.

In this paper, a record of the 14C and 13C isotope content of atmospheric CO2 for Gliwice is presented for samples collected on a weekly basis in the years 2011–2013. In addition, measurements were performed on the early and late wood from the annual rings of pine trees from five sites located 3–6 km from the atmospheric CO2 sampling point. The concentration of 14C in CO2 samples from the air was much lower relative to the concentration of this isotope in “clean air,” indicating a pronounce Suess effect, with a mean Δ14C lower by ca. 60‰ than Jungfraujoch data when the 15% of the highest differences are excluded, which leads to the FFCO2 estimate of 5.8%. In winter, the main source of fossil CO2 was fuel combustion, as confirmed by significant correlations with air pollutants. In the vegetation seasons, the Δ14C was highly variable due to biogenic influence and more variable winds. The isotopic results were also affected by an additional significant CO2 source for the Gliwice air, which was a closed mine shaft. The Δ14C and δ13C in tree rings did not record a strong Suess effect in the years 2008–2013 in woodland areas around Gliwice city.

Advances in accelerator mass spectrometry have resulted in an unprecedented amount of new high-precision radiocarbon (14C) -dates, some of which will redefine the international 14C calibration curves (IntCal and SHCal). Often these datasets are unaccompanied by detailed quality insurances in place at the laboratory, questioning whether the 14C structure is real, a result of a laboratory variation or measurement-scatter. A handful of intercomparison studies attempt to elucidate laboratory offsets but may fail to identify measurement-scatter and are often financially constrained. Here we introduce a protocol, called Quality Dating, implemented at ETH-Zürich to ensure reproducible and accurate high-precision 14C-dates. The protocol highlights the importance of the continuous measurements and evaluation of blanks, standards, references and replicates. This protocol is tested on an absolutely dated German Late Glacial tree-ring chronology, part of which is intercompared with the Curt Engelhorn-Center for Archaeometry, Mannheim, Germany (CEZA). The combined dataset contains 170 highly resolved, highly precise 14C-dates that supplement three decadal dates spanning 280 cal. years in IntCal, and provides detailed 14C structure for this interval.

The Madaras profile found at the northernmost fringe of Bácska loess plateau is one of the thickest and best-developed last glacial loess sequences of Central Europe. The 10-m profile corresponds to a period between 29 and 12 b2k. To unravel feedback to small-scale centennial climatic fluctuations at our site, recorded in the Greenland ice and North Atlantic marine cores, construction of a reliable chronology is needed. Reliability is expressed in terms of best achievable chronological precision. Accuracy however is based on choosing the model best describing the sedimentological features of our profile. Five different age-depth models had constructed and compared relying on 15 14C dates using various statistical, probabilistic approaches to choose the model with the highest achievable precision. Accuracy was also evaluated using accumulation rates against stratigraphy. Models constructed using the computer program Bacon performed best in terms of achieving the best possible stratigraphic accuracy. Seven meters of the profile represents the period of the LGM. The average sedimentation time was 16.8 yr/cm with the highest confined to the period of the LGM. Calculated average sedimentation rates were 4 times higher than previously reported. The peak accumulation periods are dated to the nadir of the LGM.

Excavations of the remains of the medieval church of Santa Maria di Campogrosso (Sicily) were conducted by the Institute of Archaeology and Ethnology of the Polish Academy of Sciences as part of scientific cooperation with Soprintendenza per i Beni Culturali ed Ambientali di Palermo. Based on the records of post-medieval historians, the construction of the church was placed in the second half of the 11th century, which contradicts the findings of architectural historians, who dated the building to the 13th-century and even later. As a result of archaeological excavations carried out in 2015–2018, it was possible to locate unknown fragments of the church’s structure and the remains of the cemetery adjacent to it. The 14C dating carried out for samples obtained from the walls of the existing building as well as from bone remains from the churchyard in combination with stratigraphic information from archaeological trenches and the chronology of coins indicates a high probability of the church construction in the second half of the 12th century and confirms the end of the monastery complex existence at the end of the 13th century.

The mortar samples of the Castle of Cannero (Lake Maggiore, Italy) have been characterized and radiocarbon (14C) dated. The presence of LDH phases was identified. The hydraulic reaction was evaluated by a multi-analytical approach. Careful extraction, preparation and purification of the binder fraction have been performed. Contaminations due to LDH phases have been removed allowing reliable absolute dating of the structures.

Non-hydraulic lime-based mortars represent only part of the binding materials found in archaeological and historical structures, and a new challenge is the application of 14C dating techniques on mortars that feature hydraulic reactions. This research work aims at 14C dating a series of Mg-rich hydraulic mortars from the Castle of Cannero (Lake Maggiore, Italy), from which both charcoals and mortar samples were collected. A multi-analytical approach employing X-ray powder diffraction (XRPD), optical microscopy (OM), and scanning electron microscopy/energy-dispersive microanalysis (SEM-EDS) was adopted in order to carefully characterize the samples. A wet gravimetric separation for the extraction of the fine fraction mainly composed by the mortar binder was carried out and the binder fraction was characterized by XRPD in order to investigate the presence of contaminants. The binding fractions are characterized by the widespread occurrence of hydrotalcite-type minerals, considered contaminants in 14C dating of mortars because of their capability to exchange carbonate anions even after the hardening process. A further purification treatment by thermal decomposition was performed before 14C dating by AMS. The obtained dates were consistent with archaeological expectations, confirming the potential of the developed purification methodology for hydraulic mortars dating.

We combine the results of a radiocarbon (14C) dating program with archaeogenetic, osteological and sparse stratigraphic data, to construct a Bayesian chronological model for a multi-generational sequence situated entirely on a plateau in the 14C calibration curve. Calibrated dates of individual human bones from the Late Neolithic gallery grave at Niedertiefenbach, Hesse, Germany, span the entire calibration plateau in the late 4th millennium (ca. 3350–3100/3000 cal BC), but our model restricts the overall period of burial to 3–6 generations centered on the later 3200s, and provides narrower absolute date ranges for specific individuals and associated events. We confirm the accuracy and robustness of this model by sensitivity tests of each of its components. Beyond providing a more dynamic narrative for the formation of the heterogenous burial population at Niedertiefenbach, our results show that calibration plateaus are suitable periods for Bayesian chronological modeling of even relatively brief sequences, provided that all the information employed is correct. Prior information constraining both the order of events, and of potential date differences between them, is essential for the model to give accurate, unimodal estimates of the dates of these events.

The Gaspereau Lake Reservoir Site Complex in Nova Scotia, Canada, yielded a large ceramic assemblage that permitted the first fine-grained analysis of ceramic change in the region at the Middle–Late Woodland Transition from ca. 1550 BP to ca. 1150 BP. The aim of this study was to refine the standard regional chronology first proposed by researchers J B Petersen and D Sanger. To do this, ceramics were directly dated using accelerator mass spectrometry (AMS), and the assemblage was categorized and analyzed to identify clusters of attributes. Ten AMS dates were acquired on carbonized food residue on the interiors of pottery and yielded the largest continuous ceramic sequence in the Maritime Provinces of Canada. This sequence was used to infer a change in manufacturing practices between the Middle (2150–1300 BP) and Late (1300–500 BP) Woodland periods and to propose five new subperiods between 1650 BP and 950 BP. Increasing incidence of coil breaks and temper percentage from the Middle to the Late Woodland were found to be chronologically sensitive. The analysis showed that, at Gaspereau Lake, a gradual shift from finely decorated and manufactured pottery to expediently made pottery suggests that pottery was made in larger numbers to support large-scale gatherings.

Subfossil trees with their annual rings constitute the most accurate and precise archive to calibrate the radiocarbon (14C) method. The Holocene part of the IntCal curve is based on tree-ring chronologies, absolutely dated by dendrochronological matching. For the Northern Hemisphere, the absolute curve starts at 12,325 cal BP. For the early part of the Younger Dryas (YD) climatic event (≈ 12,850–11,650 cal BP), there are only a few floating dendrochronological sequences, mainly from Switzerland and France. We present new 14C results from subfossil trees (Pinus sylvestris L.) collected from the Barbiers site (southeast French Alps). The dendrochronological series covers 416 years, corresponding to the onset of the YD period. In order to date our sequence, we matched it with the 14C record based on kauri trees from New Zealand. The Barbiers data were first averaged at the same decadal resolution as the kauri record. Statistical comparison of the different averaging options and matching techniques enables dating the Barbiers sequence to 13,008–12,594 ±10 cal BP, which thus includes the boundary between the Allerød and YD events. The new Barbiers record allows to calculate the 14C inter-hemispheric gradient (14C-IHG) during the period overlapping the kauri sequence. For the optimal dating option, the mean 14C-IHG is 37 yr with a standard deviation (SD) of 21 yr based on 43 decadal estimations (−6‰ with SD of 2‰). The 14C-IHG record exhibits minimal values, down to zero, between 12,960–12,840 cal BP. Excluding these minima leads to an average 14C-IHG of 45 yr with a SD of 14 yr based on 33 decadal values, in agreement with observations for the last two millennia. The Barbiers record suggests a 14C-IHG increase between the end of the Allerød period (IHG of 37 yr with SD of 14 yr) and the early part of the YD (IHG of 48 yr with SD of 14 yr), which is compatible with previously reported drop of deep-water convection in the North-Atlantic and the associated increase in wind-driven upwelling in the Southern Ocean.

Recent radiocarbon (14C) research demonstrates that the urban culture of Early-Bronze III in the southern Levant ends around 2500 BC, and not around 2300 BC as was widely assumed. This should extend the Intermediate Bronze Age by 200 years. Charred olive pits from Intermediate Bronze Age contexts in the site of Khirbat el-‘Alya Northeast in the Judean Shephelah region (Israel) were 14C dated, resulting in calibrated dates around 2500 BC. The date range of Khirbat el-‘Alya Northeast samples is an indication that in the Mediterranean parts of the southern Levant, the Intermediate Bronze Age material culture appeared around the time of the decline of the preceding culture of Early-Bronze III—around 2500 BC or somewhat earlier. Possible Intermediate Bronze settlement pattern and the site’s relation to the nearby Early-Bronze city of Tel Yarmuth are discussed based on previous Intermediate Bronze and Early-Bronze related research in the surrounding area.

Radiocarbon (14C) dating of anthropogenic carbonates (CaCO3) such as ash, lime plaster and lime mortar, has proven a difficult task due to the occurrence of a number of contaminants embedded within the CaCO3 pyrogenic binder. These include 14C-free geologic components and/or secondary phases bearing an unknown amount of 14C, and thus the alteration of the original pyrogenic isotopic signature of the material results in major age offsets when carbon recovery is performed through acid hydrolysis. Here we present a characterization/quantification approach to anthropogenic carbonates that includes Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, thin section petrography, thermogravimetric analysis and scanning electron microscopy coupled with high-resolution cathodoluminescence, with which we identified the pyrogenic CaCO3 fraction in an aerial lime plaster and two hydraulic mortars. The preserved pyrogenic component was then isolated by density separation and its purity checked again using FTIR. Carbon was recovered through thermal decomposition in vacuum. The resulting 14C age matches the expected age of the lime plaster, whereas hydraulic mortars are slightly offset due to the carbonation of calcium hydroxide lumps. This approach highlights the importance of a dedicated characterization strategy prior to dating and may be applied to aerial lime plasters to obtain accurate ages.

The 14C peak in AD 775 (M12) has been measured and confirmed globally in several studies since it was first measured in annual tree rings by Miyake et al. (2012). However, M12 data measurements in early- and latewood are limited. This paper presents the Δ14C values in early- and latewood from AD 762–776 Zelkova serrata tree rings from Bangu-dong, Ulsan, South Korea (35°33′N, 129°20′E). The results indicate no early rise in Δ14C values in the latewood of AD 774 in this sample located at mid-latitude. A comparison of the results of this and previous studies suggests latitude dependence (Büntgen et al. 2018); that is, the early rise of Δ14C in AD 774 was not observed at mid-latitudes in South Korea but was observed at high latitudes in Finland. The half-oxidation time of 14C was estimated from a detailed analysis of a small bomb peak in AD 1962. Based on the half-oxidation time, the Δ14C rise in the latewood, but not in the earlywood, of AD 774 in Finland, and the absence of a Δ14C rise in both the early- and latewood of AD 774 in South Korea, the 14C spike was estimated to have been produced from late April to mid-June in AD 774.

In this article, we investigate the chronology of a large parallel-walled mudbrick structure at the site of Pachamta in Rajasthan, India. Pachamta is larger than the contemporaneous Harappan site of Kalibangan and part of a society collectively known as the Ahar Culture. Recent excavations at Pachamta provided an opportunity to elaborate on the available dates for this society and to investigate the chronology of an enigmatic parallel-walled structure. The chronology and function of such prominent structures remains murky, although scholars have suggested that these buildings served as public storage because they resemble the granary at Harappa. Through excavation, our team collected data for assessing the Pachamta parallel-walled structure including construction methods, process of abandonment, and associated dates. The thirteen 14C assays from the site and an associated phase and sequence model performed in OxCal 4.3 demonstrate that the building was constructed, used, and abandoned in a relatively brief period. If parallel-walled structures are storage buildings, then expansion of the building may indicate prosperity or surplus, while abandonment may indicate an end to abundance or a shift in resource management. Carefully dating the structure allows us to investigate the timing of social processes including political and economic shifts within the settlement.