Intensified archaeological research in the Caribbean over the past 2 decades has provided a wealth of new information on how and when these islands were settled prehistorically. However, there has been a paucity of research on islands in the southern Lesser Antilles, which would allow for more rigorous testing of migration models and various settlement pattern hypotheses. To address some of these chronological and geographical gaps, we present a corpus of 41 radiocarbon dates from several sites in the Grenadine Island chain. Results to date support a relatively late Ceramic Age settlement of these smaller islands (about AD 400) compared to other nearby, larger islands in the southern Lesser Antilles (about AD 200) as well as the Caribbean as a whole (about 400/500 BC). Intriguing questions also remain as to an apparent, but as yet inadequately tested, pattern where earlier colonization dates are correlated with larger island size.

The current intercomparison of data from 14C laboratories reveals significant variability among liquid scintillation laboratories, suggesting that identical samples submitted to different laboratories may yield values that differ by much more than expected on a purely statistical basis. Erroneous dates (recently corrected) by a well-established 14C laboratory give rise to further concern for quality 14C data. Thus, it is incumbent on each laboratory to develop and implement a quality assurance and control (QA/QC) program in order to ensure accuracy of results and to alert lab personnel to problems.

Direct accelerator mass spectrometry (AMS) dating of anaerobically preserved plant remains from the Dongan site in New Guinea, combined with assessment of preservation condition, confirms earlier doubts about the antiquity of betelnut (Areca catechu L.) found at the site. A possible sago leaf fragment is also identified as a modern contaminant. The mid-Holocene age of other fruit and nut remains is verified using these methods. The utility of AMS dating in combination with detailed archaeobotanical assessment is demonstrated, thus improving chronometric hygiene and with it knowledge of past plant use in Oceania.

Recently, in an intercomparison of the Hohenheim German oak chronology (Becker 1993) and the Göttingen chronology (Leuschner and Delorme 1988), an error was discovered in the former (Leuschner, in preparation). Due to an error in adding sections at 5241 bc, 41 yr are missing in the published Hohenheim chronology. After correction of the error, the two chronologies synchronize over their entire common length, back to 7200 bc.

We present a time-saving modification to the ultraviolet (UV) oxidation method for analyzing dissolved organic carbon (DOC) concentration, Δ14C, and δ13C measurements in seawater and standard materials. A low background (∼0.2 ± 0.2 μM) was reported for pre-irradiated Milli-Q (MQ) water that was used to dilute samples for DOC 14C analysis (Beaupré et al. 2007). We use MQ water without pre-irradiation (background ∼0.9 ± 0.2 μM) to dilute the sample. This method is suitable for small-volume, high-concentration samples (mass of sample DOC overwhelms mass of MQ water DOC). An acceptable precision of Δ14C measurements (5–9‰) is maintained. This revised method reduces the preparation time for diluted DOC Δ14C samples from 2 days to 1 day.

Two radiocarbon excursions (AD 774–775 and AD 993–994) occurred due to an increase of incoming cosmic rays on a short timescale. The most plausible cause of these events is considered to be extreme solar proton events (SPE). It is possible that there are other annual 14C excursions in the past that have yet to be confirmed. In order to detect more of these events, we measured the 14C contents in bristlecone pine tree-ring samples during the periods when the rate of 14C increase in the IntCal data is large. We analyzed four periods every other year (2479–2455 BC, 4055–4031 BC, 4465–4441 BC, and 4689–4681 BC), and found no anomalous 14C excursions during these periods. This study confirms that it is important to do continuous measurements to find annual cosmic-ray events at other locations in the tree-ring record.

Accurate radiocarbon (14C) dating of lime mortars requires a thorough mineralogical characterization of binders in order to verify the presence of carbon-bearing contaminants. In the last 20 years, cathodoluminescence (CL) has been widely used for the identification of geologic calcium carbonate (CaCO3) aggregates and unreacted lime lumps within the particle size fraction selected for carbon recovery. These components are major sources of older and younger carbon, respectively, and should be removed to obtain accurate age determinations. More recently, laser-induced fluorescence (LIF) has provided another means of investigating the preservation state and composition of CaCO3 binders. Considered the growing interest of the mortar dating community in the latest advancements of these analytical methods, here we review the principles of CL and LIF of CaCO3, their instrument setup, and their application to the characterization of ancient lime mortars used for 14C dating. In addition, we provide examples of SEM-CL and LIF analyses using high-resolution instrumentation, we discuss current issues and propose future lines of research.

The direct measurement of organic matter included in archaeological pottery may yield a reliable assessment of age. The main problem consists in the identification of possible origins and assessment of distortion for the age of organic inclusions. Our experiments show that shells included in pottery fabrics are strongly influenced by the reservoir effect, which may reach 500 yr or more. Other organic inclusions, such as lake ooze, do not visibly distort the age. The obtained series of radiocarbon dates have been used for the assessing the age of the early stages of pottery manufacture in southern Russia.

This article is a rejoinder to a recent paper in this journal by van der Plicht et al. (2009) who use radiocarbon determinations from several sites in Israel, Italy, Spain, and Tunisia to advocate a High Chronology system for the entire Mediterranean Basin. We contend that they reached mistaken conclusions due to problematic selection of sites and data. We argue that a reliable way to provide absolute dates for the Iron Age in the central and western Mediterranean is by employing a combination of well-identified Greek pottery found in well-stratified sites and radiometric results from short-lived samples. For the time being, this combination exists only in the Levant, and provides an anchor for Greek chronology, which supports the Conventional Chronology for the Aegean Basin, which corresponds to the Low Chronology in the Levant.

New results of radiocarbon concentration in tree rings from the Kraków region covering a growth period of 20 yr have been analyzed, and the relationship between them and 14C concentrations in the atmospheric CO2 are described. This enabled assessment of the uptake period for pine trees at the regional climatic conditions. Both sets of data show lower 14C concentrations than reported for “clean air” at the reference station, indicating a remarkable input of “dead” CO2 of fossil fuel origin. Using data of carbon dioxide and 14C concentrations from Schauinsland, summer values of the fossil component (Cf) in carbon dioxide were calculated for the Kraków area. Fitting exponential and linear functions to experimental data, the exchange time was calculated, and expected future 14C concentration in the atmosphere was estimated.

Radiocarbon dating of charcoal in soils is commonly used to reconstruct past environmental processes. Also microcharcoal that is chemically isolated from soil organic matter by high-energy UV photo-oxidation can be dated with 14C accelerator mass spectrometry (AMS). We compared the 14C AMS ages of 13 pairs of hand-picked macrocharcoals and microcharcoal samples separated via the UV oxidation method; both charcoal fractions were taken from the same soil samples (prehistoric pit fillings). We found that in most cases, the microcharcoal fraction yielded older ages than the single macrocharcoal pieces, and that the differences between the ages are not systematic. A reason for these age differences might be that the microcharcoal fraction consists of more stable components than macrocharcoals and thus yields older ages. Dating of microcharcoal would give a mean age of charred organic matter in soil material and the ages of the more stable compounds. Thus, 14C data obtained from the microcharcoal fraction in soils is not comparable to macrocharcoal ages and should not be used to complement existing macrocharcoal data sets.

This article presents new radiocarbon evidence from the Middle Bronze Age palatial site of Tel Kabri (Israel). The final phase of the palace (Phase III) can be dated to Middle Bronze Age II, with an end date around the transition from Middle Bronze II to III or very early in Middle Bronze III. According to our 14C data, the end of Tel Kabri Phase III (and thus the transition from Middle Bronze II to III) can be dated to ~1700 BC. This date is about 50–100 yr earlier than traditional chronological models for the Middle Bronze Age propose (~1650 BC according to the traditional chronology or ~1600 BC according to the low chronology). 14C data from Tel Kabri thus add additional evidence for a higher Middle Bronze Age chronology for the Levant, consistent with recent 14C evidence from Tell el-Dabca (Egypt), Tel Ifshar (Israel), and Tell el-Burak (Lebanon).

I describe a simple, rapid and inexpensive method for converting CO2 samples into AMS target graphite. The technique is applicable for both small- and large-scale production facilities. With some modification, the method is suitable for use with very small samples.

We studied a 12.6-m-long sequence from Lake Abiyata (Central Ethiopia) to establish a reliable and accurate chronology for use in global paleoclimatic reconstructions. The 26 accelerator mass spectrometry radiocarbon (AMS 14C) ages, performed on carbonates and organic matter, define 2 parallel chronologies, representing the complete Holocene period. However, these chronologies show a significant discrepancy from 500 to 900 BP in depth; ages obtained on carbonates were always older than those on organic matter. The hydrogeological and geochemical behavior of the Lake Abiyata basin has shed light on this discrepancy. We found that the carbonate crystallization is due mainly to the mixing of lake waters with groundwaters from the multi-layered aquifer contained in the 600-m-thick basement of the lake. The 14C activity of total dissolved inorganic carbon (TDIC) measured by AMS from bottom and surface lake waters (111.4 and 111.8 pMC, respectively) confirms that the mixing occurs at the water-sediment interface. This evidence of groundwater participation in the carbonate crystallization calls into question the current paleoclimatic reconstructions based on inorganic carbonates in lakes. Specific attention should thus be given to the respective proportions of each end-member in the mixing for the quantitative estimation of the groundwater input. This will help to validate the paleoenvironmental reconstructions and to highlight an eventual diagenetical evolution of inorganic carbonates during burial, via the study of pore waters.

The Radiocarbon Dating Laboratory of the Department of Geology, University of Lyon, is going on with work since its foundation in 1965, in the basement of the Nuclear Physics Institute.

The recently established low-level radiation laboratory of Scripps Institution of Oceanography has been measuring radiocarbon since August 1957. Through 1959 about 160 samples have been measured.

This paper focuses on the chronological study of 2 Scythian period monuments that are the key to the chronology of the entire Eurasian Scythian culture. These are the unique monuments of Arzhan-1 and Arzhan-2 in Central Asia (Tuva Republic). The dating of both these monuments began immediately after their discovery, but discussion about their chronological position is still current. Both monuments contained considerable wooden material from their construction suitable for dendrochronology and radiocarbon dating. The first results for the Arzhan-1 barrow were obtained by wiggle-matching in 2004–2005, while the Arzhan-2 barrow was first dated in 2003. It is now possible to compare the chronological position of these barrows using the same methods. As postulated earlier, Arzhan-1 is the oldest Scythian period monument and is dated to the boundary of the 8–9th centuries BC. The position of the Arzhan-2 monument stretches to the middle of the 7th century BC. δ13C values for annual tree rings in logs from both barrows were also determined to gain a better understanding of the climatic conditions at the time of barrow construction.

We have observed A14C concentrations in the northern hemisphere temperate region in the bomb pulse period, using cross-dated tree ring samples. The tree-ring samples were taken from one 70-year-old and two 50-year-old red pines (Pinus densiflora) on Mt Chiak, Korea and from a 50-year-old red pine (Pinus densiflora) on Mt Kyeryong, Korea. Twenty-two tree-ring samples from four red pines ranging from 1950 to 2000 AD were pretreated to obtain holo-cellulose, combusted to CO2 by an element analyzer (EA) and converted to graphite for δ14C measurement using the accelerator mass spectrometry (AMS) facility at Seoul National University. Our results for δ14C showed good agreement with those measured by other researchers at similar latitudes. The observed steady decrease of δ14C from 1965 to 2000 AD is described by a single exponential function with a lifetime τ = 15.99 ± 0.43 yr. This lifetime is similar to that of the high-latitude region in Europe.

New excavations and new 14C dates at the Gruta del Indio shelter in the central Argentinean Andes show that the dung layer of the site is much thicker towards the front of the site than near the rock wall. This yields a longer chronology for the dung deposit; thus, the upper boundary would date to about 9000 14C yr BP. The new measurements lengthen the possible time of the coexistence of man and extinct Pleistocene megafauna in the area, since ≃1400 cal yr is much longer than previously thought (Long et al. 1998). Nevertheless, coexistence does not imply interaction, which still is not evident.

A heuristic approach, nicknamed “transition dating,” was used to date sequences of early Iron Age contexts using a series of 14C determinations. The basic principles of transition dating are simple and intuitive: 1) attempt to date transitions between periods, phases, etc. rather than the phases themselves, and 2) the most plausible date for that transition is one that is later than the dates from contexts preceding it, and is still earlier than the dates succeeding it. Hypotheses regarding the actual date of each transition may be evaluated using an appropriate loss function. These loss functions can also be adjusted or weighted by the user to account differentially for the various factors causing the distortion or “fuzz” in the dates.