Archaeological surveys conducted in the Negev and Sinai during the 20th century were commonly interpreted as representing short settlement periods interrupted by long gaps. The time factor was usually based on archaeological estimates rather than comprehensive physical dating. For example, the perceived age and time duration of “hole-mouth” pottery sherds and tabular flint scrapers became a source of circular reasoning to “date” sites and their “duration.” Thus, desert sites became to be perceived as temporary, seasonal, short-lived, while the cultures of desert populations were somehow undervalued. However, radiocarbon dating of desert sites from the Late Neolithic to the Early Bronze Age IV presents a very different scenario. The deserts of the Southern Levant exhibit a full sequence of settlement, a longer life span of individual sites, and a higher level of activity and creativity of the desert people. This paper describes the controversy and presents the 14C data that form the basis for the revised view.

The palynological sequence of the Hula L07 core was previously correlated with the global oxygen isotope stages 3–5, based on a radiocarbon age determination and comparison with other Levantine paleoclimatological curves. An attempt was made to validate this correlation with Th/U dating. Unlike typical European peat, which is acidic, the soil pH of the Hula peat is mildly basic. Not only does this contribute to the oxidation of palynomorphs, but it also helps to preserve the carbonate material that can be a variable mixture of allogenic, endogenic, and authigenic components. Each component may represent a different degree of uranium series disequilibrium. The thorium (232Th) concentrations of the carbonate are low. Total digestion or acid leach of the sample may not always enable the proper correction for initial thorium. The dating derived from a NaOH-extraction of the organic material, while giving apparently better ages, also suffers from the presence of the carbonate admixture. It appears that, while 14C dating can be considered suitable for the younger portions of the core, techniques based upon the U-series may not be as efficacious in dating this important record of climatic change.

Radiocarbon age determinations of wood charcoal are commonly used to date past forest fire events, even though such ages should be greater than the fire event due to the age of the wood at the time of burning. The difference in the 14C-derived age of charcoal and the time-since-fire (the “inbuilt age”) may be considerable in some vegetation types and thus must be estimated before interpreting fire dates. Two methods were used to estimate the potential range of inbuilt age of soil charcoal dated to determine ages of forest fires on the west coast of Vancouver Island (Canada). First, 26 14C ages on charcoal in surficial soil were compared directly with ages of forest fire determined by tree-ring counts, suggesting inbuilt ages of 0–670 years. Second, a simulation model that uses estimated fuel loads, fuel consumption, charcoal production, and the ages of charred wood (time since wood formation), suggests that the combination of slow growth rates and slow decay rates of certain species can account for inbuilt ages of more than 400 years in this forest type. This level of inbuilt age is large enough such that the actual age of a fire may not occur within the 2σ confidence interval of a calibrated charcoal 14C age determination, and thus significantly affect the interpretation of fire dates. A method is presented to combine the error of a calibrated 14C age determination with the error due to inbuilt age such that the larger adjusted error encompasses the actual age of the fire.

We have undertaken extensive programs of natural radiocarbon measurement to date the evidence for various events buried in peat bogs. Two case studies are described here: 1) the chronological reconstruction of South Kamchatka volcanic eruptions and, 2) investigation of multi-layered archeological sites in the Upper Volga River Basin. Studies of sample composition and peat taphonomy allowed us to determine the source of 14C age deviations and to reconstruct the environmental history of organic matter accumulation. Data sets, obtained from different types of peat bog and containing traces of these Holocene events, are discussed.

In recent years, High Voltage Engineering Europa (HVEE) has demonstrated its capability of developing and installing turnkey accelerator mass spectrometry (AMS) equipment for the analysis of, among others, 14C and 129I. Five 3MV systems using sequential and/or simultaneous injection are operational in the field today, and they have shown excellent long-term stability providing high-precision analyses on a routine basis. Another three AMS systems are in production. It is projected that for the time being, AMS will continue to broaden its field of applications; a saturation of the market of AMS facilities is not expected in the near future.

To meet the specific demands of the biomedical research community, we have developed an extreme compact 14C AMS system comprising a hybrid ion source capable of handling both graphite as well as CO2 samples. The source is optimized for easy maintenance, accommodates up to 200 samples, and can be implemented in any other AMS system.

More recently, HVEE has initiated the development of an AMS system capable of detecting, among others, 36Cl and 41Ca. The design will include a HVEE 5MV Tandetron™. The accelerator is currently under construction as part of an ion beam analysis system for the Universidad Autonoma de Madrid (Spain).

This article reports on ten new accelerator mass spectrometry (AMS) dates from the Chalcolithic period (fifth millennium BC) archaeological type-site of Teleilat Ghassul in Jordan. Early radiocarbon assays from the site proved difficult to integrate with current relative chronological formulations. The ten new AMS dates and follow-up enquiries connected with the early assays suggest that the original dates were up to 500 years too early. A necessary reformulation of regional relative chronologies now views the Ghassul sequence falling between Late Neolithic Jericho and the Beersheban Chalcolithic.

Lynch's Crater in northeastern Australia provides a long, continuous record of environmental change within the Late Quaternary. Here, we present newly determined radiocarbon ages, using acid-base-acid stepped combustion (ABA-SC) and acid-base-wet oxidation stepped combustion (ABOX-SC) pretreatment strategies. The new results largely confirm the original untreated radiocarbon results for the uppermost 9 m of sediments, (ca. 35 ka BP). Below this depth, results from both pretreatment methods are in stratigraphic agreement and extend the dating of the record from 38 ka BP to about 48 ka BP, although an apparent increased sedimentation rate below 12 m is questionable. The scarcity of “charcoal” in several of the samples raises questions regarding the application of ABOX-SC to lake or swamp sediments, with evidence for contributions from younger, chemically resistant bacterial carbon along with fine “charcoal” in some samples. However, the extent to which this phenomenon is significant to the final age estimate appears to be sample specific, and is probably dependent upon the length of the wet oxidation step in the pretreatment.

The chronology study of the cemetery of Marquises of Jin is valuable to improving the chronological table of Marquis of Jin family. It is also helpful for improving the chronological table of the Zhou Dynasty. The samples were measured at Peking University (PKUAMS). We also made an interlaboratory check with Isotrace to ensure the accuracy. By careful analysis of archaeological information, we built different models and calibrated by OxCal. The calibration results, both sampling contexts and estimations, are in very good agreement with the historical record. Because the dates of some events correspond to the special part of the curve, the calibration gets very high precision. The calibration result of tomb M93 suggests that its host is Marquis Shangshu instead of Marquis Wen.

Radiocarbon measurements by two 1220 Quantulus™ ultra low background liquid scintillation spectrometers were performed at the underground laboratory of Gran Sasso and the Radiocarbon Laboratory of E.N.E.A.-Bologna to study the efficiency and background variations related to measurement sites. The same configuration setup, i.e. the same center of gravity of the 14C spectrum (SQP(I) = 410 ± 1) was obtained in both instruments. Many different background and modern standards with pure analytical benzene were used and spectra for 40 one-hour periods were obtained. The data indicates a background reduction of approximately 65% between the surface and underground laboratories, with no differences in the efficiency. Recording similar efficiencies in both spectrometers is probably due to fairly identical photomultiplier characteristics. The cosmic noise reduction observed at the laboratory of Gran Sasso makes it possible to perform high precision 14C measurements and to extend for these idealized samples the present maximum dating limit from 58,000 BP to 62,000 BP (5 mL, 3 days counting).

Archaeological evidence suggests that the Chalcolithic period (5th–4th millennium BCE) in the southern Levant was a time of significant settlement expansion and increasing social complexity. Important technological and social developments during this era set the stage for the later rise of fortified sites and nascence of urbanization in the Early Bronze Age. Controversy surrounding the chronology of Chalcolithic settlement and the reconstruction of social trajectories has stimulated an interest in building a database of radiocarbon dates to measure the tempo of change and help resolve these issues. To facilitate social evolutionary research, this paper reviews and updates published 14C data for the southern Levantine Chalcolithic. The now-substantial database supports the generally accepted time frame for this archaeological period and allows synchronic comparisons across diverse geographic subregions in the southern Levant. In addition, it helps to temporally place the emergence of sophisticated technologies and the development of complex social institutions within the Chalcolithic period. However, radiometrically based attempts at pan-regional internal periodization of the Chalcolithic and fine-tuning of protohistoric events such as site establishment and abandonment are frustrated by the lack of precision in 14C dates, which limits their ability to resolve chronological sequence. Improved delineation of Chalcolithic social trajectories can be achieved most effectively by focussing research efforts on stratigraphic and typological investigations of deeply-stratified settlement sites such as Teleilat Ghassul and Shiqmim within their local contexts.

Two lake and bog sediments have been thoroughly studied using palynological and radiocarbon dating methods. These are the Lembolovskoye Lake section located in the southern part of the Karelian Ithmus and the Mshinskoye bog section located in the southwestern part of the Leningrad province. The data obtained allow us to reconstruct the main features of the vegetation cover evolution, the chronology for the appearance and a real distribution of the main arboreal species from the south of the Leningrad province to the north, and to construct curves of the paleoclimate parameter changes for the area under study. Thirty-six 14C dates were obtained for the Lembolovskoye Lake section (7 m thick). According to those dates, the organic gyttja formation in the lake began 9870 ± 170 BP. Spore-pollen spectra with high percentage of herbs, arborescent, and shrub-birch dated back to the Younger Dryas were found out in clay layers at a depth of 6.5 m. An appearance of spruce and alder pollen is dated at 6860 ± 120 and 7510 ± 150 BP, respectively. The maximal percentage of broad-leaved species falls on the first half of the Atlantic (AT-1). Thirty-two dates were obtained for the Mshinskoye bog section (6 m thick): from 60 : 70 to 9520 ± 170 BP (the last date fixed the beginning of peat formation); 12 palinozones from the Preboreal to the Subatantic were recognized there. The spruce and alder pollen began to appear 7520 ±110 and 7670 ± 130 BP, respectively. The maximal amount of broad-leaved species is observed at 4690 ± 80 BP. The detailed reconstruction of changes in vegetation communities during the Late Glacial and Holocene was correlated with paleoclimatic characteristics, which have been recontructed for the sections under study by using the information from a statistical method of spore-pollen data processing.

The Mulifanua ferry berth has the distinction of being the only site in Samoa with dentate-stamped Lapita wares, and is the most easterly Lapita site in the Pacific. Two new radiocarbon determinations of material associated with Lapita pottery found at Mulifanua are presented. The accuracy of this data is evaluated according to the results of recent reassessment of pottery from the site, and current theories regarding the age of Lapita settlement in the eastern Pacific. The resulting calibrated radiocarbon ages put occupation of the Mulifanua Lapita site at around 2880–2750 cal BP (930–800 BC). This conclusion is in agreement with the pottery chronology and supports recent hypotheses of rapid Lapita settlement in the Fiji/Tonga region around 2850–2700 cal BP (900–750 BC).

During the last decade radiocarbon dating has been used extensively in distinct regions of Brazil to provide information about soil chronology in paleoenvironmental studies. This paper presents 14C data of soil organic matter (SOM), humin fraction, and charcoal in several soil profiles under natural vegetation from different Brazil locations (north, central, and southeast regions). The main objective is to compare the obtained 14C dating of total SOM with humin, the oldest fraction of SOM. In order to validate the humin ages these data are compared with the age of charcoal collected at similar depths. The 14C ages obtained on charcoal were, in most of the cases, in agreement with the humin fraction considering the experimental errors, or 20% older in average. The dates obtained from total SOM showed significantly younger ages than the humin fraction indicating contamination by younger carbon. These results show the humin fraction is considered a reliable material for 14C dating in soils. However, the humin fraction ages could be assumed as the minimum ages for carbon in soils.

The accelerator mass spectrometry facility at the Seoul National University (SNU-AMS) was completed in December 1998 and a report was presented at the Vienna AMS conference in September 1999. At the conference, we described the basic components of our accelerator system and reported the results of the performance test. Since then, extensive testing of the accuracy and reproducibility of the system has been carried out, and about 200 unknown samples have been measured so far. We obtained a precision of 4‰ for modern samples, and an accuracy of approximately 40 yr was demonstrated by analyzing samples that were previously dated with a conventional technique and by other AMS laboratories. We present these results here, together with detailed descriptions of our data-taking and analysis procedures.

Modern radiocarbon dates were procured for the Cave of the Treasure, Israel reed mat at the University of Arizona accelerator mass spectrometry (AMS) laboratory in late 1999 and early 2000. Three samples from various locations on the mat were dated. One of these samples was dated twice, and another was dated three times, yielding a total of six new radiocarbon dates on the mat. The new 14C dates overturn expectations of a late Chalcolithic, roughly 3500 BC, date for the origin of the mat. It is suggested that the mat may not have been of common use but may rather have been a religious heirloom with a history stretching back into the early Chalcolithic.

A date of 4300 ± 90 BP for extinct megafauna in Argentina is discussed. The fossil remains come from the Guerrero Member (area) of the Luján Formation near the city of Luján, Buenos Aires Province. The age of the top of the Guerrero Member is constrained by more than 60 radiocarbon dates obtained from the overlying Río Salado Member of Luján Formation, Las Escobas Formation, and Puesto Callejón Viejo Soil, most of them older than 4300 BP. In view of its low collagen content, the 14C measurement of bone sample from Luján should not be accepted uncritically. Because of the poor bone preservation and the possible introduction of “young” contaminants that were not completely eliminated, the 14C date of 4300 ± 90 BP is not reliable. Both biostratigraphic and 14C dating evidence indicates that the date of 4300 BP for the last representative of extinct megafauna in South America is unsupported.

The wide and varied connections between Israel and Egypt during the Early Bronze Age/Predynastic are frequently calibrated through ceramics that depend to a large degree on two seriation methods developed for Predynastic Egypt. Petrie's seriation technique and Kaiser's Stufe dating method utilize whole forms from mortuary contexts. Because of the ways they were developed and deployed in Predynastic research, a logical tautology exists that makes their usage highly problematic. Radiocarbon dating of the Predynastic is vital if we are to untangle existing ceramic chronologies. But up to now, almost all 14C dates have come from domestic contexts where whole vessels are not usually found and which differ significantly from cemeteries in their ceramic assemblages. A 14C-based chronology of whole forms in the Petrie Corpus is thus highly desirable, but has proven elusive until now. Samples of organic materials and Black-Topped Red Ware vessels from over 100 graves in the Predynastic Cemetery, N7000, at Naga-ed-Dêr have recently been submitted for dating with AMS methods, providing the first comprehensive 14C chronology of a Predynastic cemetery. The results are compared to a suite of recalibrated dates from Upper Egyptian Predynastic domestic contexts, which allows the 14C chronology for the region to be further refined. Absolute date ranges for a number of ceramic forms can be estimated for the first time, and results of early analysis are discussed.

Radiocarbon dates were analyzed to assess Vertisols age around the world. They show an increase of radiocarbon age from mainly modern–3000 BP in 0–100 cm layer up to 10,000 BP at a depth 100–200 cm. Older dates reflect the age of parent material. The inversion of 14C dates seems to be a frequent phenomenon in Vertisols. A series of new dates of Vertisols from gilgai microhigh, microslope and microlow in the North Caucasus was done in order to understand the nature of this inversion. 14C age in the gilgai soil complex ranges from 70 ± 45 BP in the microlow to 5610 ± 180 BP in the microhigh. A trend of similar depths being younger in the microslope and microlow was found. We explain this by intensive humus rejuvenation in the microlows due to water downward flow. The older date in the microhigh represents the old humus horizon sheared laterally close to the surface and preserved by impermeable water regime. We explain inversions of 14C age-depth curves by the sampling procedures. In a narrow pit, genetically different parts of former gilgai could easily be as a genetically uniform soil profile. Because of this strong microvariability, Vertisols require sampling in a trench accounting for gilgai elements, even when gilgai are not obvious.

Measurements of the radiocarbon concentration of several carbonate background materials, either mineral (IAEA C1 Carrara marble and Icelandic double spar) or biogenic (foraminifera and molluscs), show that the apparent ages of diverse materials can be quite different. Using 0.07 pMC obtained from mineral samples as a processing blank, the results from foraminifera and mollusc background samples, varying from 0.12 to 0.58 pMC (54.0-41.4 ka), show a species-specific contamination that reproduces over several individual shells and foraminifera from several sediment cores. Different cleaning attempts have proven ineffective, and even stronger measures such as progressive hydrolization or leaching of the samples prior to routine preparation, did not give any indication of the source of the contamination. In light of these results, the use of mineral background material in the evaluation of the age of older unknown samples of biogenic carbonate (>30 ka) proves inadequate. The use of background samples of the same species and provenance as the unknown samples is essential, and if such material is unavailable, generic biogenic samples such as mixed foraminifera samples should be used. The description of our new modular carbonate sample preparation system is also introduced.