With the development of radiocarbon dating methods in the last decade, the Andean archaeological community has successfully leaned into the problem of the chronology of the expansion of the Inca State. While this chronology was based on ethnohistorical accounts (Rowe 1945), it has been possible to verify its foundations precisely in the last decade. The results from the Maucallacta region are part of these discussions and are intended to add new data from the Inca province of Kuntisuyu, which was neglected in this debate until now. The project encompasses archaeological investigations near the snow-covered volcano Coropuna, frequently mentioned by chroniclers of the 16th and 17th centuries as an oracle worshiped since pre-Inca times. This includes a large complex known as Maucallacta-Pampacolca, located approximately 170 km northwest of Arequipa in the southern highlands of Peru, within the District of Pampacolca, Province of Castilla, Department of Arequipa (LS; 3750 m asl). Due to its location, it holds a unique relationship with the Coropuna landscape. The site is a vast administrative center featuring over three hundred stone buildings, tombs, and ceremonial structures. Among them, the most important is the large ceremonial platform with ushnu and the dumps deposited beneath it. The analysis of ceramics and animal bones, combined with stratigraphic analysis and the results of new calibrations and interpretations of radiocarbon dates, provides a comprehensive picture of the formation and use of ceremonial dumps at the site, making them one of the most thoroughly examined collections in this regard.

The floating dendrochronological sequence of pine wood from Józefowo, N. Poland was expected to cover the ∼660 BC radiocarbon (14C) excursion. The sequence was radiocarbon dated using the OxCal wiggle matching procedure and the IntCal20 calibration curve. 14C concentrations were measured in one-year α-cellulose samples from around 660 BC. The published data on the ∼660 BC 14C excursion from Grabie, Poland were used to absolute date the Józefowo chronology with 1-year accuracy. The results confirm the occurrence of a rapid increase in Δ14C in 664/663 BC and its potential to be used as a fixing point for floating dendrochronological sequences.

The Early Iron Age hillfort in Chotyniec (SE Poland) is the westernmost permanent settlement of the Scythian cultural circle. Recognizing the construction of the fortified settlement’s ramparts and their chronology was considered one of the priorities of the systematic research conducted since 2016. Based on 18 radiocarbon dated samples from different parts of the rampart, a chronological model of its functioning was made. It indicates that the construction of this monumental fortifications protecting the settlement in Chotyniec should be dated to between 651–595 or 531–409 BC. This dating synchronizes well with the chronology of the most important ritual and ceremonial object within the Chotyniec settlement—the so-called zolnik and other Scythian settlements from the East European forest-steppe zone.

The article presents results of measurements of radiocarbon (14C) concentration in sub-annual dendrochronologically dated tree rings of English oak (Quercus robur L.) from Grabie village near Kraków (southern Poland). Samples of early wood (EW) and late wood (LW) spanning the years 664–658 BCE. α-cellulose was extracted from each sample and their radiocarbon content was measured at the ATOMKI laboratory in Debrecen, Hungary. The EW and LW data confirm a prolonged increase in Δ14C values around 665–663 as was observed by Park et al. (2017), Rakowski et al. (2019), or Sakurai et al. (2020). In addition, we found that this event may consist of two relatively small events, as was proposed by Sakurai et al. (2020). Based on obtained in this and previous study data we estimate that the occurrence of the two events were between 665 and 664 BCE (Rakowski et al. 2019), and in late spring of 663 BCE (May–June, before beginning of LW formation).

This study presents a new stable oxygen isotope chronology, covering the years 800–2000 AD, constructed using modern and subfossil wood derived from trees growing around Lake Schwarzensee in Austria. The climatic signal imparted in the chronology is conditioned mainly by the direct influence of environmental factors on the isotopic signature of source water, which in turn is regulated by evaporation and condensation mechanisms. The second driver of stable oxygen isotope is the physiological response of trees to changing weather conditions, most importantly rates of transpiration. The chronology of stable oxygen isotopes corresponds well with both temperature (r = 0.485; p < 0.05) and total precipitation (r = −0.548; p < 0.05) during the growing season (May–September). This mixed signal results from the fact that the relationship between the content of stable oxygen isotopes and the influence of climate is multifactorial. Moreover, the effect exerted by meteorological conditions on stable isotope ratio changes over time. This is most probably linked to interannual variation in climatic and environmental factors.

The chronology of Machu Picchu was traditionally associated with the period attributed to the reign of Pachacuti Inca Yupanqui. Within the scheme of the so-called “historical chronology”, proposed by John H. Rowe in 1945, the ascension to power of Pachacuti Inca took place around 1438 CE, and the construction of Machu Picchu began by 1450–1460 CE. Several radiocarbon-dated samples may help to understand the chronology of the construction of llaqta of Machu Picchu, Chachabamba, and Choqesuysuy. However, there is a lack of consensus between different radiocarbon-based Inca chronologies because of the lack of information of which calibration curves to use: Northern Hemisphere (NH), Southern Hemisphere (SH), or a mixed calibration curve? Thus, the main goal of the present investigation is to develop a new methodological approach to reconstruct a radiocarbon-based Incan chronology, an approach based on the determination, through modeling, of the proportion of NH and SH air parcels arriving at three relevant Inca settlements. We found air parcel contributions from the NH and SH for Machu Picchu (51% NH and 49% SH), Chamical (29% NH and 71% SH), and Tiquischullpa (41% NH and 59% SH). Thereby, our investigation brings three proportions to mix NH and SH 14C curves, based on an empirical method and supported by a high-resolution paleoclimatic tracer, for Inca radiocarbon dating studies. Our study emphasizes that great attention should be paid when applying radiocarbon calibration to radiocarbon measurements of samples originating from regions under the influence of the atmospheric circulation-boundary between hemispheres.

This article presents measurements of the radiocarbon (14C) concentration in sub-annual tree rings. Samples of earlywood (EW) and latewood (LW) from dendrochronologically dated tree rings (English oak, Quercus robur) from Kujawy, near Kraków (Poland), spanning the years of 990–997 CE, are extracted and their 14C content is measured at the Center for Applied Isotope Studies at the University of Georgia, USA. The EW and LW data show a gradual increase in the Δ14C values between 991–995 CE, which are similar to those observed by Rakowski et al. (2018). An increase of 10.3 ± 2.6‰ in Δ14C for the EW data, and 8.6 ± 2.6‰ for the LW data has been recorded for this period. Using this data, it is possible to estimate the time period for when a major historical event occurred, which seems to have been in the late summer (September –2/+1 month) of 993 CE.

Determining the biocomponents in liquid fuels using radiocarbon radioisotope (14C) dating requires sample preparation adaptations to the conditions of the Gliwice Radiocarbon and Mass Spectrometry Laboratory. Liquid scintillation counting (LSC), and accelerator mass spectrometry (AMS) were investigated using six samples, including one 14C-free fuel and modern hydrotreated vegetable oil (HVO). For AMS, samples were prepared using tin capsules for liquids for EA combustion and graphitization in an AGE system. For LSC, liquid fuels were prepared by mixing with purified preheated sand and a benzene synthesis line. Benzene resublimation was also tested. IRMS measurements were also conducted for benzene to account for isotopic fractionation. Sample background measurements using both methods showed good performances by both AMS and LSC without resublimation. Comparable results were also obtained for HVO.

Radiocarbon (14C) analyses are commonly used to determine the absolute age of floating tree-ring chronologies. At best, with the wiggle-matching method, a precision of 10 years could be achieved. For the early Middle Ages, this situation has been markedly improved by the discovery of rapid changes in atmospheric 14C concentrations in tree-rings dated to 774/775 and 993/994 AD. These high-resolution changes can be used to secure other floating tree-ring sequences to within 1-year accuracy. While a number of studies have used the 774 even to secure floating tree-ring sequences, the less abrupt 993 event has not been so well utilized. This study dates a floating pine chronology from Ujście in Wielkopolska (Greater Poland) (NW Poland), which covers the 10th century period and is critical for studies on the beginning of the Polish State to the calendar years 859–1085 AD using the changes in single year radiocarbon around 993/4 AD.

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.

Miyake et al. (2012, 2013, 2014) described a sudden increase of radiocarbon (14C) concentration in annual tree rings of Japanese cedar (Cryptomeria japonica) and Hinoki cypress (Chamaecyparis obtusa) between AD 774 and 775 and between AD 993 and 994. In both analyzed periods, the sudden increase was observed almost in a single year. The increase in the 14C content was about 12‰ in the period AD 774–775 (Miyake et al. 2012) and about 11.3‰ in the period AD 993–994 (Miyake et al. 2013, 2014; Fogtmann-Schultz et al. 2017; Rakowski et al. 2018). A similar increase was observed in 660 BC, with a peak height of about 10‰ (Park et al. 2017). Single-year samples of dendrochronologically dated tree rings of deciduous oak (Quercus robur) from Grabie, a village near Krakow (SE Poland), spanning the years 670–652 BC, were collected and their 14C content was measured using an AMS technique. The results clearly show a rapid increase in the 14C concentration in tree rings around 660 BC similar to this observed in Park et al. (2017).

This paper presents the results of radiocarbon (14C) dating of bulk mortars and reports an attempt of implementation of the knowledge about the isotopic fractionation, based on δ13C measurements, to make the age correction for mortars, together with verification of such correction based on the percentage estimation of carbonate components, namely binder and aggregate. To evaluate the variability of isotopic fractionation during CO2 absorption by mortar, dependent on the climatic and environmental conditions, and the type of mortar, the δ13C measurements have been performed for the mortars from Sussita (Golan Heights). Such measurements were also made for fragments of natural carbonate rocks and for mortars produced in the laboratory from the same substrate. We propose the recipe for mortars age estimation.

An increase in atmospheric radiocarbon (14C) content of about 11.3‰ in the period AD 993–994 was observed in annual tree rings from Japanese cedar (Cryptomeria japonica) and Hinoki cypress (Chamaecyparis obtusa) (Miyake et al. 2013, 2014). Single-year samples of dendrochronologically dated tree rings (English oak, Quercus robur) from Kujawy, a village near Krakow (SE Poland), spanning the years AD 981–1000, were collected, and their 14C content was measured using the AMS system in the Leibniz Laboratory. The results clearly show an increase of 6.2±1.6‰ in the 14C concentration in tree rings between AD 993 and 994, with a maximum increase of 10.9±1.7‰ between AD 991 and 994.

Liquid scintillation counting (LSC) for radiocarbon dating is a less expensive method than accelerator mass spectrometry (AMS), provides a high degree of accuracy, and is less prone to contamination due to the larger sample sizes. However, to obtain high precision, a long counting time is needed. The Gliwice Radiocarbon Laboratory is seeking to obtain an increased counting capacity with 2–3 mL benzene samples than we presently can achieve with our 2 Quantulus systems. We are therefore investigating the possibility of using a simple, single-phototube LS system (ICELS) for dating samples younger than 5000 yr. We present the first results of this investigation, including the measurement of 3 VIRI and 3 FIRI intercomparison samples.

Santa Lucía is a pottery production site dating to the Formative period (about 1600 BC to AD 200). It is located in the Cochabamba valleys of the eastern Bolivian Andes. The settlement consists of a residential area and a separate workshop area. A peripheral sector of ash mounds was used as refuse sites and burial grounds. The excavations yielded a total of 16 radiocarbon samples from all 3 sectors, which were dated at the Gliwice Radiocarbon Laboratory (Gliwice, Poland). The results from the deepest trench in the workshop sector (Trench 5) provide information for the stratigraphic sequence and help to define spatial and socioeconomic changes at around 600–500 BC with the beginning of the Late Formative or Santa Lucía III phase. The 14C dates from Santa Lucía, therefore, contribute to a better definition of the existing regional Formative period phases and finally to a better understanding of the processes during the Formative period in the south-central Andes.

Oxbow lake deposits of the Neris River at the Valakupiai site in Vilnius (Lithuania) have been studied by different methods including radiocarbon dating. A timescale was attained for the development of the oxbow lake and climatic events recorded in the sediments. 14C dates obtained for 24 samples cover the range 990–6500 BP (AD 580 to 5600 BC). Medieval human activity was found in the upper part of the sediments. Mollusk fauna found in the basal part of the terrace indicate contact between people living in the Baltic and the Black Sea basins. Mean rates were calculated for erosion of the river and for accumulation during the formation of the first terrace.

New records of δ13C and Δ14C values in annual rings of pine and oak from different sites around the world were obtained with a time resolution of 1 yr. The results obtained for Europe (Poland), east Asia (Japan), and South America (Peru) are presented in this paper. The δ13C and radiocarbon concentration of α-cellulose from annual tree rings of pine and of the latewood of oak were measured by both accelerator mass spectrometry (AMS) and liquid scintillation spectrometry (LSC). The values of 14S, which represent decreasing 14C concentrations caused by the emission of CO2 from fossil fuel use (Suess effect; Suess 1955), were calculated for each site. Low average 14S (about −0.4 to 0.8%) values for clean areas and high values (about 3.4–3.6%) for industrial and/or urbanized areas were noted. Records of the δ13C values obtained for pine and oak from Poland were used to reconstruct climate changes during the last 400 yr. The results clearly indicate the climate cooling during the periods of the Maunder minimum (1645–1715) and the Dalton minimum (1790–1820). The anti-correlation between the δ13C and Δ14C records during those 2 periods is clear if the 14C record is shifted toward older ages by 24 yr.

The ongoing Ychsma Project aims to shed light on the chronology and function of the late Prehispanic period at the well-known archaeological site of Pachacamac, Peru, through extensive archaeological research. The Temple of the Monkey is a special building that has been cleared, mapped, and excavated within the general framework of the study of “pyramids with ramps,” the most common form of monumental architecture at the site. Through the application of radiocarbon measurements, it can be shown that the temple has been used for around 150 yr and therefore is quite different from other pyramids with ramps previously studied (see Michczyński et al. 2003). Details of the temple, 14C sample selection, and methodology, as well as results, are discussed in this paper. The research has allowed us to make significant advances in the current understanding of pyramids with ramps and the function of the site of Pachacamac as a whole.

Mesolithic sites in modern Poland are mainly located in the southern part of the country. Radiocarbon dating of organic material, such as charcoals, wood, and peat, provide a time frame of human settlements in those regions, and dating of speleothems and peat formations provide information on climatic conditions and the timing of climatic change in the region. Here, we present the results of calibrated 14C ages from 3 main Mesolithic sites: Glanów, Chwalim, and Całowanie. Summary probability density distributions of the calendar ages were obtained, and time ranges were ascribed to the cultures in conjunction with archaeological information. These distributions also reveal the changes in human settlement.

This work is a study of changes of the radiocarbon concentration in the youngest part of Lake Gościąż sediments in the calendar time scale during the last 150 years. This period includes the time of the nuclear weapons tests performed in the upper atmosphere in the 1950s and the 1960s, which caused large release of 14C and 137Cs into the environment. On the basis of this study, the isotope dilution factor for 14C and the exchange time of carbon between the atmosphere and Lake Gościąż was estimated. The chronology of the upper part of the sediments was constructed using many interdisciplinary investigations. Among them, measurements of 137Cs in the sediment were used. An unexpected discrepancy between the previously constructed time scale and that suggested by 137Cs is observed in one of the cases.