Archival charcoal tree-ring segments from the Mississippian center of Kincaid Mounds provide chronometric information for the history of this important site. However, charcoal recovered from Kincaid was originally treated with a paraffin consolidant, a once common practice in American archaeology. This paper presents data on the efficacy of a solvent pretreatment protocol and new wiggle-matched 14C dates from the largest mound (Mound 10) at Kincaid. FTIR and 14C analysis on known-age charcoal intentionally contaminated with paraffin, as well as archaeological material, show that a chloroform pretreatment is effective at removing paraffin contamination. Wiggle-matched cutting dates from the final construction episodes on Mound 10 at Kincaid, indicate that the mound was used in the late 1300s with the construction of a unique structure on the apex occurring around 1390. This study demonstrates the potential for museum collections of archaeological charcoal to contribute high-resolution chronological information despite past conservation practices that complicate 14C dating.

A laboratory intercomparison project was carried out on 20 annually resolved late-wood samples from the Danish oak record. The project included the following three laboratories: (1) the University of Arizona AMS Laboratory, University of Arizona, USA (AA); (2) HEKAL AMS Laboratory, MTA Atomki, Hungary (DeA); and (3) Aarhus AMS Centre (AARAMS), Aarhus University, Denmark (AAR). The large majority of individual data points (96%) lie within ±2σ of the weighted mean. Further assessment of the accuracy associated with the individual laboratories showed good agreement, indicating that consistent and reliable 14C measurements well in agreement with each other are produced at the three laboratories. However, the quoted analytical uncertainties appear to be underestimated when compared to the observed variance of differences from the geometric mean of the samples. This study provides a general quality check of the single-year tree-ring 14C measurements that are included in the new calibration curve.

This study obtained calendar dates by radiocarbon accelerator mass spectrometry (14C AMS) dating sequential tree-rings of wooden support posts from the buried remains of traditional Kitkahahki Pawnee earthlodges preserved at an archaeological site on the Central Great Plains, USA. The tree-ring segments from the site were dendrochronologically analyzed prior to this study, but the cross-matched site chronology could not be definitively cross-dated and was thus “floating” in time. Our study represents the first floating tree-ring chronology from the Great Plains to be anchored in time by means of independent radiocarbon analysis. Three specimens were analyzed and dated to 1724–1774 CE (82.0% probability), 1774–1794 CE (95.4% probability), and 1800–1820 CE (95.4% probability). These dates correspond to the hypothetical timing of Kitkahahki ethnogensis, the main phase of village growth in the area, and a later reoccupation during a turbulent period in regional history. The results of this study conform to a scenario in which chaotic social conditions correspond to an increase in residential mobility between the core of Pawnee territory and a southern frontier in the Republican River valley.

In 2018 Pearson et al. published a new sequence of annual radiocarbon (14C) data derived from oak (Quercus sp.) trees from Northern Ireland and bristlecone pine (Pinus longaeva) from North America across the period 1700–1500 BC. The study indicated that the more highly resolved shape of an annually based calibration dataset could improve the accuracy of 14C calibration during this period. This finding had implications for the controversial dating of the eruption of Thera in the Eastern Mediterranean. To test for interlaboratory variation and improve the robustness of the annual dataset for calibration purposes, we have generated a replicate sequence from the same Irish oaks at ETH Zürich. These data are compatible with the Irish oak 14C dataset previously produced at the University of Arizona and are used (along with additional data) to examine inter-tree and interlaboratory variation in multiyear annual 14C time-series. The results raise questions about regional 14C offsets at different scales and demonstrate the potential of annually resolved 14C for refining subdecadal and larger scale features for calibration, solar reconstruction, and multiproxy synchronization.

South-west Transylvania was an important source of metal and other natural resources for Bronze Age Europe, helping to facilitate the development of increasingly hierarchical societies. The absence of a radiocarbon-based chronology for Transylvania, however, has impeded understanding of the region's role within broader socioeconomic networks. Here, the presentation of the first radiocarbon chronology for the Wietenberg Culture in south-west Transylvania allows the authors to highlight the importance of interregional exchange and reliable access to metal for Bronze Age European societies, and emphasise that resource-procurement zones follow unique trajectories of socioeconomic organisation.

We quantified Δ14C, δ18O, and δ13C cycles along ontogeny within four bay scallop (Argopecten purpuratus) shells collected from Callao Bay, Salaverry, and Sechura Bay, Peru following the 1907–1908 non-El Niño years and the 1925–1926 El Niño. Δ14C and δ13C generally covary; Δ14C and δ18O vary inversely. Simultaneous decreases in Δ14C and increases in δ18O in non-El Niño shells are followed by constant Δ14C and gradually decreasing δ18O, which we interpret as evidence for discrete marine upwelling events followed by warming of the initially cold upwelled water. Upwelling changes from El Niño events are detectable with difficulty in mollusk shell Δ14C.

Since the mid-19th century, western Oregon's Willamette Valley has been a source of remains from a wide variety of extinct megafauna. Few of these have been previously described or dated, but new chronologic and isotopic analyses in conjunction with updated evaluations of stratigraphic context provide substantial new information on the species present, timing of losses, and paleoenvironmental conditions. Using subfossil material from the northern valley, we use AMS radiocarbon dating, stable isotope (δ13C and δ15N) analyses, and taxonomic dietary specialization and habitat preferences to reconstruct environments and to develop a local chronology of events that we then compare with continental and regional archaeological and paleoenvironmental data. Analysis of twelve bone specimens demonstrates the presence of bison, mammoth, horse, sloth, and mastodon from ~ 15,000–13,000 cal yr BP. The latest ages coincide with changing regional climate corresponding to the onset of the Younger Dryas. It is suggested that cooling conditions led to increased forest cover, and along with river aggradation, reduced the area of preferred habitat for the larger bodied herbivores, which contributed to the demise of local megafauna. Archaeological evidence for megafauna–human interactions in the Pacific Northwest is scarce, limiting our ability to address the human role in causing extinction.

The chronology of the Mesolithic, Neolithic, Aeneolithic, and Bronze Age sites in the Trans-Urals (Russia) was studied, and a framework for previously established cultural complexes is suggested based on 153 radiocarbon dates. In this new chronological model, the Mesolithic is dated to ~10,000–6500 cal BC; the Neolithic complexes exist at ~6500–3800 cal BC; the Aeneolithic is dated to ~4300–2800 cal BC; the Early Bronze Age spans ~2500–2100 cal BC; and the Late Bronze Age can be preliminary assigned to ~1600–1100 cal BC.

The earliest years of photography were full of experimentation and innovation; many photographers from this era carefully documented their experimental procedures. Consequently, it is possible to reproduce historically accurate photographs and negatives today. One of the oldest forms of photographic technology is the waxed paper negative, popular during the mid-19th century. It consists of a photosensitive sheet of writing paper coated with a layer of wax to render it transparent. Modern waxed paper negatives made using 19th century paper can potentially pass for historically significant 19th century negatives. This poses problems to museums and others interested in studying or collecting authentic 19th century photographic images. We have developed methods for separating the organic components of waxed paper negatives and measuring their radiocarbon content as a means of distinguishing between modern and historic waxed paper negatives. By detecting the presence or lack of bomb carbon in a given negative, this process can act as a tool for authentication. We have mainly focused on the extraction and 14C measurement of the wax component, reasoning that modern photographers might have easy access to 19th century paper, but would less likely use 19th century beeswax.

This paper reports the results of the application of a calcined bone dating protocol to samples collected from the Sanctuary of Zeus on Mt. Lykaion in southern Greece. The site is a mountaintop ash altar rich in anthropogenic sediments, burned bone, and artifacts offered to the god Zeus. Experiments involving time series hydrolysis measurements were conducted on calcined bones from stratified layers throughout the sequence to determine if any of the samples underwent surface contamination from carbonate exchange with the surrounding sedimentary matrix. It was determined that such exchange was unlikely, but samples were acid-etched before pretreatment as a precautionary measure. Paired samples of seeds, charcoal, and calcined animal bone collected from a sediment column in the altar demonstrate the effectiveness of the calcined bone dating technique in this context. The results of dating indicate that the altar was in use from the Mycenaean period through the late Classical period, though samples were not collected from the upper levels of the site due to possible mixing of surface sediments. Fourier transform infrared spectroscopy (FTIR) measurements were taken and crystallinity index values calculated, confirming that the bone samples are indeed calcined. The results presented here correspond with literary accounts of ritual animal sacrifice from historical texts from the 8th century BCE, including the Homeric epics.

This research aims at radiocarbon dating 2 structures of archaeological interest from Petra, south Jordan, using lime plaster and mortar. Initially, the samples' content of calcareous contamination was examined by petrography and cathodoluminescence. In order to date clean lime binders, the samples were gently crushed and 63–45 μm powders were collected by dry sieving, then the CO2 gases, collected by a hydrochloric acid hydrolysis of the powders, were dated. The interpreted 14C dates clarify the chronology of the studied structures, show an agreement with the archaeological and historical data, and may indicate the efficiency of the cleaning and hydrolysis procedures.

This investigation concerns human teeth and bones from the site of Natfieh, north Jordan. Nitrogen and carbon isotope analyses were used to model the paleo-economy by reconstructing Natfieh's paleodiet during a specific time period. 14C dating of human teeth and bones from the site of Natfieh, north Jordan, demonstrate that they belong to the Early Roman period and match the archaeological date from the tomb and grave goods typology. Stable isotope analyses of these humans have provided new information about the subsistence and society of individuals buried at Natfieh. Natfieh is today agriculturally productive and must have been so in antiquity with most of the foodstuffs having been produced locally. The long distance between Natfieh and the closest aquatic food source (Mediterranean Sea and Lake Tiberias) and the high cost of land transportation might be the reason for the low consumption of marine protein. The results agree with past research on the Roman diet showing that plants were the common source of food for the Romans and fish may have been restricted to elite members of the society.

Mollusk shells provide brief (<5 yr per shell) records of past marine conditions, including marine radiocarbon reservoir age (R) and upwelling. We report 21 14C ages and R calculations on small (∼2 mg) samples from 2 Mesodesma donacium (surf clam) shells. These shells were excavated from a semi-subterranean house floor stratum 14C dated to 7625 ± 35 BP at site QJ-280, Quebrada Jaguay, southern Peru. The ranges in marine 14C ages (and thus R) from the 2 shells are 530 and 170 14C yr; R from individual aragonite samples spans 130 ± 60 to 730 ± 170 14C yr. This intrashell 14C variability suggests that 14C dating of small (time-slice much less than 1 yr) marine samples from a variable-R (i.e. variable-upwelling) environment may introduce centuries of chronometric uncertainty.

The Great Plains of North America have a rich archaeological record that spans the period from Late Glacial to Historic times, a period that also witnessed significant changes in climate and ecology. Chronometric dating of archaeological sites in many areas of the Great Plains, however, is often problematic, largely because charcoal and wood—the preferred materials for radiocarbon dating—are scarce in this grassland environment with few trees. Two reference archaeological sites are studied here: Mustang Spring and Lubbock Lake, Texas, USA. We carry out a geochronological approach based on a cross-study of carbon-derived data: combustion yield, δ13C, 14C age differences between high temperature and low temperature released carbon, and the 14C age itself. A study that incorporates multiple approaches is required to solve issues induced by the sedimentological context, which is rich in both freshwater diatoms and phytoliths from quite different origins. Analysis of carbon-derived data allows us to draw a succession model of dry and wet episodes and to associate it with a chronological framework. In this way, we can assert that, for the Mustang Spring site, several human occupations existed from ∼11 kyr BP to ∼8.7 kyr BP along the 110-cm-long series with an interruption of ∼150 yr that is associated with a palustrine environment between the Plainview and Firstview occupations.

Marine upwelling along coastal Peru can be intense and variable, making radiocarbon dating marine and coastal systems complex. Historical and proxy records of upwelling along coastal Peru are few, and long-lived species such as corals do not grow in the cold coastal waters. Mollusk shell carbonate, however, can record both the magnitude of the local marine reservoir correction, ΔR, and of seasonal oscillations in the ventilation age of coastal waters. If large, these seasonal oscillations would complicate radiocarbon dating of marine organisms. To examine this possibility, we sampled for δ13C, δ18O, and 14C content a set of pre-bomb Argopecten purpuratus shells collected from coastal Peru during 1908 and 1926. Intrashell variations of up to 216 14C yr were noted, but these were not consistently correlated with seasonal changes in δ18O or δ13C. Only an 11 yr difference was observed in the weighted average ΔR of Callao Bay shells collected during normal (1908) and El Niño (1926) years. Despite the intrashell 14C variation noted, weighted average ΔR values from all 3 sample sites and from normal and El Niño years all overlap at 1 σ. We report ΔR values of 183 ± 18 and 194 ± 23 yr from Callao Bay (12°4′S), 165 ± 24 yr from Salaverry (8°14′S), and 189 ± 23 yr from Sechura Bay (5°45′S).