Determining calendar ages for radiocarbon dates, or ordered sequences of radiocarbon dates, that intersect with a plateau on the radiocarbon calibration curve can be problematic since, without additional prior constraints, the calendar age ranges determined will tend to spread across the plateau, yielding wide and less than useful calendar age probability densities and age ranges. Where possible, modeling analysis should seek to identify informative priors that act to restrict the otherwise poorly controlled spread of probability across plateaus. Such additional information may be available, among other sources, from the stratigraphy, the context, or the samples themselves. The recent dating of ordered sequences of radiocarbon dates on sections of branches of the same olive (Olea europaea) shrub from Therasia (southern Aegean) associated with the Minoan eruption of the Thera (Santorini) volcano (Pearson et al. 2023), which intersect with the plateau in the radiocarbon calibration curve ca. 1620–1540 BC, offers an example of the problem. A re-analysis adding some plausible informative priors offers a substantially better defined likely dating range and different conclusions. Instead of finding an inconclusive probability range “encompassing the late 17th and entire 16th century BC” followed by arguments for “indications of increased probabilities for a mid-16th century BC date for the eruption,” a re-analysis incorporating appropriate informative priors identifies the likely date range as falling between the late 17th to early 16th centuries BC.

Five sites in present-day New York have played important roles in archaeological narratives surrounding the development of settled village life in northeastern North America. Excavated in the mid-twentieth century, the Roundtop, Maxon-Derby, Sackett or Canandaigua, Bates, and Kelso sites include evidence related to the transition from semisedentary settlement-subsistence patterns during the twelfth through fourteenth centuries AD to those associated with fifteenth century and later settled Iroquoian villagers. Radiocarbon dates for each site were obtained early in the development of the method and again following the transition to AMS dating. Here, we present new or recently-published dates for these sites, combined with reliable existing dates in Bayesian models, including in some cases short tree-ring sequenced wiggle-matches on wood charcoal. Our results clarify the timing of each site’s occupation(s), revealing both continuity and discontinuity in the development of longhouse dwellings, sedentism, and the repeated re-use of some site locations over hundreds of years.

The rich architectural heritage of Cyprus from the period of Byzantine and Latin rule includes 10 churches inscribed in the UNESCO World Heritage list. Most of these monuments preserve wooden elements: whether structural, decorative or furnishings. Many preserve wall paintings that are considered among the best examples of Byzantine and Medieval art in the Eastern Mediterranean. The dating of these paintings as well as the church buildings themselves, has been based mainly on style, with occasional dedicatory inscriptions and related historical interpretation. We report early results from a project investigating the wooden cultural heritage of Cyprus and in particular the combined use of dendrochronology with radiocarbon via tree-ring sequenced 14C wiggle-matching to help place initial tree-ring sequences. This includes a floating 264-year Pinus brutia chronology from several monuments, which, with a ca. 5-year gap, suggests prospects for >700-years of P. brutia chronology for Cyprus, and, with one gap of several decades to fill, ca. 1100 years of Pinus nigra chronology for Cyprus. Several currently floating elements from the multi-phase UNESCO-listed Timios Stravros church at Pelendri, including a terminus post quem for the celebrated liturgical wooden cross, are approximately dated across the 11th to 16th centuries AD.

The Lamoka Lake and Scaccia sites in present-day New York have played important roles in the development of archaeology in New York, and in the case of Lamoka Lake, in eastern North America. Lamoka Lake is the type site for the “Archaic” period in eastern North American culture history and the “Late Archaic” “Lamoka phase” in New York culture history. The Scaccia site is the largest “Early Woodland” “Meadowood phase” site in New York and has the earliest evidence for pottery and agriculture crop use in the state. Lamoka Lake has been dated to 2500 BC based on a series of solid carbon and gas-proportional counting radiometric dates on bulk wood charcoal obtained in the 1950s and 1960s. Scaccia has been dated to 870 BC based on a single uncalibrated radiometric date obtained on bulk charcoal in the early 1970s. As a result, the ages of these important sites need to be refined. New AMS dates and Bayesian analyses presented here place Lamoka Lake at 2962–2902 BC (68.3% highest posterior density [hpd])) and Scaccia at 1049–838 BC (68.3% hpd).

Dates differ by up to 150 years in the protracted debate around the chronology of the Middle Bronze Age Near East. Here, the authors present radiocarbon and ceramic evidence from destroyed buildings at Zincirli, Türkiye, that support the Middle Chronology. Ceramics from late Middle Bronze Age sites in Syria and Anatolia, and Bayesian modelling of 18 well-stratified radiocarbon samples from site destruction contexts attributable to Hittite king Ḫattusili I, indicate a date in the later seventeenth century BC. Since the Northern Levant connects the Mesopotamian and Eastern Mediterranean second-millennium BC chronologies, this evidence supports the convergence of these long-debated schemas, with implications for the start of the Late Bronze Age and the rise of empires.

Studies of ancient Mediterranean trade and economy have made increasing use of sophisticated modelling and network analyses of shipwreck evidence. The dating of most of these wrecks, however, is based solely on assessments of associated ceramic material, especially transport amphorae. The resulting dates are approximate at best, and, as the example of the recently investigated Mazotos ship highlights, sometimes incorrect. Here, the authors describe a widely applicable independent approach based on the integration of tree-ring analysis and radiocarbon dating. Interrogating the subjective assumptions and stepwise logic transfers involved in ceramic-based dating, the authors demonstrate how to produce a more robust and better-defined basis for the analysis of the ancient Mediterranean shipwreck record.

Considered in isolation, the radiocarbon (14C) dates on short-lived plant remains from the Jean-Baptiste Lainé (formerly Mantle) site, Ontario, yield an ambiguous result: more or less similar probability around AD 1500 or alternatively around AD 1600. This village site, likely of no more than ca. 20–30 years total duration, illustrates the challenges of high-resolution dating across periods with a reversal/plateau in the 14C calibration curve. Another problem we identify is the tendency for dating probability for short-duration sites to sometimes be overly compressed as dating intensity increases under analysis with OxCal, and for probability to shift away from the real age range especially during reversal/plateau episodes. To address both issues additional constraints are necessary. While a tree-ring sequenced 14C “wiggle-match” is the best option where available, we investigate how, in the absence of such an option, use of the in-built age in wood-charcoal samples can be used to distinguish the likely correct date range. This approach can resolve ambiguities in dating, e.g., for shorter-duration Late Woodland village sites in northeastern North America, but also other short-duration cases corresponding with reversal/plateau episodes on the 14C calibration curve. We place the Jean-Baptiste Lainé site most likely in a range between ca. AD 1595–1626 (95.4% probability).

Extensively worked in antiquity, Skouriotissa remains the only active copper mine on the island of Cyprus. The modern, open-cast operation, however, has almost completely obliterated the earlier mining landscape. Here the authors report the results of investigations, including dating, of the ancient topography of the mine. They incorporate spatial data derived from archival sources, recent fieldwork and absolute dating into a geographical information system to reconstruct the ancient mining landscape around Skouriotissa. Their approach holds promise for understanding other mining regions in Cyprus and beyond, by providing an example of how diverse source material can be used to reconstruct landscapes now destroyed or buried by open-cast mining operations.

This article presents results to date of the Dating Iroquoia project. Our objective is to develop high-precision radiocarbon chronologies for northeastern North American archaeology. Here, we employ Bayesian chronological modeling of 184 AMS radiocarbon dates derived from 42 Northern Iroquoian village sites in five regional sequences in order to construct new date estimates. The resulting revised chronology demands a rethinking of key assumptions about cultural process in the region regarding the directionality and timing of processes of coalescence and conflict and the introduction of European trade goods. The results suggest that internal conflict may have preceded confederacy formation among the Haudenosaunee but not the Wendat, as has been previously assumed. External conflict, previously thought to have begun in the early seventeenth century, began more than a century earlier. New data also indicate that the timing and distribution of European materials were more variable between communities than acknowledged by the logic underlying traditional trade-good chronologies. This enhanced chronological resolution permits the development and application of archaeological theories that center the lived experiences and relational histories of Iroquoian communities, as opposed to the generalized thinking that has dominated past explanatory frameworks.

According to the classical chronology of the Inca State, the ascension to power of Pachacuti Inca took place around AD 1438 and the construction of Machu Picchu began by AD 1450–1460. However, the improvement in the accuracy of radiocarbon (14C) dating resulting from the application of Bayesian analysis has changed our view of the historical chronology. This new research raises questions about our understanding of the cultural development of the Machu Picchu area, in the light of the new proposed chronological scheme. This paper presents a set of 11 new 14C dates, derived from AMS, from the sites of Llaqta of Machu Picchu, Chachabamba, and Choqesuysuy. The latter two sites are situated within the Machu Picchu National Archaeological Park (Arqueología del Santuario Histórico Nacional y Sitio Patrimonio Mundial de Machu Picchu) and have been interpreted as being part of the contemporary Late Horizon Inca landscape. The new 14C ages are modeled using Bayesian inference and present a revised dating framework for these sites and their chronological relationship with Llaqta of Machu Picchu.

Radiocarbon (14C) ages cannot provide absolutely dated chronologies for archaeological or paleoenvironmental studies directly but must be converted to calendar age equivalents using a calibration curve compensating for fluctuations in atmospheric 14C concentration. Although calibration curves are constructed from independently dated archives, they invariably require revision as new data become available and our understanding of the Earth system improves. In this volume the international 14C calibration curves for both the Northern and Southern Hemispheres, as well as for the ocean surface layer, have been updated to include a wealth of new data and extended to 55,000 cal BP. Based on tree rings, IntCal20 now extends as a fully atmospheric record to ca. 13,900 cal BP. For the older part of the timescale, IntCal20 comprises statistically integrated evidence from floating tree-ring chronologies, lacustrine and marine sediments, speleothems, and corals. We utilized improved evaluation of the timescales and location variable 14C offsets from the atmosphere (reservoir age, dead carbon fraction) for each dataset. New statistical methods have refined the structure of the calibration curves while maintaining a robust treatment of uncertainties in the 14C ages, the calendar ages and other corrections. The inclusion of modeled marine reservoir ages derived from a three-dimensional ocean circulation model has allowed us to apply more appropriate reservoir corrections to the marine 14C data rather than the previous use of constant regional offsets from the atmosphere. Here we provide an overview of the new and revised datasets and the associated methods used for the construction of the IntCal20 curve and explore potential regional offsets for tree-ring data. We discuss the main differences with respect to the previous calibration curve, IntCal13, and some of the implications for archaeology and geosciences ranging from the recent past to the time of the extinction of the Neanderthals.

Reversals and plateaus in the radiocarbon (14C) calibration curve lead to similar 14C ages applying to a wide range of calendar dates, creating imprecision, ambiguity, and challenges for archaeological dating. Even with Bayesian chronological modeling, such periods remain a problem when no known order—e.g., a stratigraphic sequence—exists, and especially if site durations are relatively short. Using the reversal/plateau AD 1480–1630 and the archaeology of northeastern North America as our example, we consider possible strategies to improve chronological resolution across such reversal/plateau periods in the absence of stratigraphic sequences, including uses of wood-charcoal TPQs from even very short wiggle-matches, and site phase duration constraints based on ethnohistoric and archaeological evidence.

Radiocarbon dating is rarely used in historical or contact-era North American archaeology because of idiosyncrasies of the calibration curve that result in ambiguous calendar dates for this period. We explore the potential and requirements for radiocarbon dating and Bayesian analysis to create a time frame for early contact-era sites in northeast North America independent of the assumptions and approximations involved in temporal constructs based on trade goods and other archaeological correlates. To illustrate, we use Bayesian chronological modeling to analyze radiocarbon dates on short-lived samples and a post from four Huron-Wendat Arendarhonon sites (Benson, Sopher, Ball, and Warminster) to establish an independent chronology. We find that Warminster was likely occupied in 1615–1616, and so is the most likely candidate for the site of Cahiagué visited by Samuel de Champlain in 1615–1616, versus the other main suggested alternative, Ball, which dates earlier, as do the Sopher and Benson sites. In fact, the Benson site seems likely to date ~50 years earlier than currently thought. We present the methods employed to arrive at these new, independent age estimates and argue that absolute redating of historic-era sites is necessary to accurately assess existing interpretations based on relative dating and associated regional narratives.

The South Caucasus occupies the divide between ancient Mesopotamia and prehistoric Europe, and was thus crucial in the development of Old World societies. Chronologies for the region, however, have lacked the definition achieved in surrounding areas. Concentrating on the Tsaghkahovit Plain of north-western Armenia, Project ArAGATS's multi-site radiocarbon dataset has now produced Bayesian modelling, which provides tight chronometric support for tracing the transmission of technology, population movement and social developments that shaped the Eurasian Bronze and Iron Ages.

Although dendrochronological methods have the potential to provide precise calendar dates, they are virtually absent in Mesoamerican archaeological research. This absence is due to several long-standing, but erroneous, assumptions: that tree rings in this region do not reflect annual growth and environmental variability, that an adequate number of samples do not exist, and that tree-ring measurements cannot be useful without modern trees to link prehispanic chronologies. In this article we present data from the sites of La Quemada and Los Pilarillos, located in the Malpaso Valley, Zacatecas, to demonstrate that suitable archaeologically derived samples of dendrochronologically useful species do exist, that the samples from these sites are measurable and cross-datable, and that the tree rings can yield precise calendar dates using a method that “wiggle-matches” radiocarbon dates on tree-ring sequences. The work demonstrates the potential of these methods to address chronological, and, in the future, climatic questions, which have so far eluded archaeological work in the region.

The date of the Late Bronze Age Minoan eruption of the Thera volcano has provoked much debate among archaeologists, not least in a recent issue of Antiquity (‘Bronze Age catastrophe and modern controversy: dating the Santorini eruption’, March 2014). Here, the authors respond to those recent contributions, citing evidence that closes the gap between the conclusions offered by previous typological, stratigraphic and radiometric dating techniques. They reject the need to choose between alternative approaches to the problem and make a case for the synchronisation of eastern Mediterranean and Egyptian chronologies with agreement on a ‘high’ date in the late seventeenth century BC for the Thera eruption.

During the 1st millennium AD, a fundamental set of changes in ship design, building methods, and sequence of construction took place in the Mediterranean. This process is known as the “Transition in Construction.” Before the Transition, ship hull design was based longitudinally on the ship's strakes (“shell-first”). By about the mid-1st millennium AD, the concept and construction of ship hulls had changed and were based on the ship's frames (“frame-based”). The Transition was a complex, nonlinear evolution. High-precision dating of the construction and service period of ships built during the 1st millennium is essential for elucidating the Transition process. Such dating precision is possible using radiocarbon wiggle-matching and Bayesian analysis techniques. The following study uses these techniques to determine the construction, launch, and final voyage (wrecking) dates of Dor 2001/1, a Byzantine shipwreck from northern Israel that was built based on frames. The results indicate that Dor 2001/1 was likely constructed and launched in the first third of the 6th century AD and was wrecked no later than AD 540. This is one of the earliest frame-based ships found in the Mediterranean so far. Dor 2001/1 is therefore an important shipwreck in understanding the Transition, since it provides evidence that frame-based hulls were already being built by the mid-1st millennium AD, about 500 yr earlier than has been commonly accepted.

The IntCal09 and Marine09 radiocarbon calibration curves have been revised utilizing newly available and updated data sets from 14C measurements on tree rings, plant macrofossils, speleothems, corals, and foraminifera. The calibration curves were derived from the data using the random walk model (RWM) used to generate IntCal09 and Marine09, which has been revised to account for additional uncertainties and error structures. The new curves were ratified at the 21st International Radiocarbon conference in July 2012 and are available as Supplemental Material at www.radiocarbon.org. The database can be accessed at http://intcal.qub.ac.uk/intcal13/.