Most of the 14C measurements reported here were made between October 1976 and October 1977. Equipment, measurement, and treatment of samples are as reported previously (R, 1968, v 10, p 36-37; 1976, v 18, p 290).

Most of the 14C measurements reported here were made between October 1978 and October 1979. Equipment, measurement, and treatment of samples are as reported previously (R, 1968, v 10, p 36-37; 1976, v 18, p 290) except for some minor improvements of the electronic equipment. Sediment samples too small to allow pretreatment, are now burned at <650°C in order to avoid pyrolysis of carbonates that may be present in the samples. Same max combustion temperature is used for samples with suspected graphite contamination. A movable thermocouple (Philips TERMOCOAX TCI 30/50/3) in the combustion zone is used for checking the temperature.

A simplified model of hydrological changes during the Late Glacial and Holocene is presented for the northern Polish regions that were ice covered during the Last Glacial. This reconstruction is based on a group of 197 radiocarbon dates from about 120 localities reflecting the sequence of alternating lake transgressions and regressions. The earliest transgressions were related to dead-ice melting (sometimes in 2–3 phases), while the later ones started during more humid phases. However, these were usually followed by regressions, which may have been connected with the formation of new drainage systems and with the overgrowing of shallow lakes by peat bogs.

The radiocarbon (14C) dating facility at the Centre for Isotope Research, University of Groningen went through a major upgrade in 2017 and this included installation of a MICADAS accelerator mass spectrometer (AMS). In the first 18 months, we performed 4000 sample and 3000 reference measurements. A careful evaluation of those measurement results is presented, to characterize the various sources of uncertainty and to ultimately assign, for every sample measurement, a realistic expanded uncertainty. This analysis was performed on the measurements of secondary references and sample duplicates in various phases of their processing steps. The final expanded uncertainty includes both the 14C measurement uncertainties and uncertainties originating from pretreatment steps. Where the 14C measurement uncertainty includes straightforward uncertainties arising from Poisson statistics, background subtraction, calibration on Oxalic Acid II and δ13C correction, the uncertainties originating from pretreatment steps are based on the spread of actual measurement results for secondary references and sample duplicates. We show that the 14C measurement uncertainty requires expansion, depending on the number of processing steps involved prior to a 14C measurement, by a maximum factor of 1.6 at our laboratory. By using these expansion (multiplication) factors, we make our reported uncertainty both more realistic and reliable.

Archaeological plant remains, used to establish a reliable chronology by radiocarbon dating, are used here to investigate trends in past rainfall intensity. The stable carbon isotope ratio in botanic remains depends on environmental conditions during the plant's life. By comparing the δ13C and 14C of selected plant specimens from 3 protohistoric sites in the Aeolian Archipelago, it is possible to identify short-term changes in the rainfall intensity during the 2nd millennium BC. The climate signals inferred from carbon isotope analyses are compared to pollen data for the region and are found to be consistent with changes in vegetal cover. Finally, the climate signals are integrated with the history of the Aeolian communities and the resilience of settlers is evaluated.

Comparison of two sets of marsh-accumulation records from each of three Connecticut (USA) salt marshes, one based on individually calibrated dates and the other on wiggle-match dating of the same series of dates, shows that wiggle-match dating results in more precise and objective reconstructions of longer-term (102–103 yr) changes in accumulation rate. On (sub-)century time scales, wiggle-match dating can reveal steps in the calibrated marsh-accumulation envelope as artefacts of the calibration curve, but may also leave real short-term changes in accumulation rate undetected. Wiggle-matches are non-unique, being dependent on the number, quality and distribution of radiocarbon dates in a sequence, how a series of dates is subdivided into groups (representing intervals of uniform accumulation rate), and what is considered a “best match”. Samples from the studied salt-marsh deposits required no correction for reservoir effects prior to calibration.

Half a century since radiocarbon was first used in the archaeology of the Old World, it seems that the expectations of W F Libby may be becoming a reality. In 1952 (Libby 1952:97), he wrote:

Archaeologists, geologists and palynologists are continually searching for the means to improve methods of counting time. The … relative chronologies lack precision and direct correlation with the calendar, except when they may be checked with, … for example, the calendar based on tree-ring counts.

The C14 measurements reported here were made in this laboratory between January 1969 and July 1970. Details of our apparatus, sample preparation, and measuring procedure were described in R., 1968, v. 10, p. 144–148. A change has been made since January 1969: strontium carbonate is reduced to strontium carbide with a mixture of 60g of SrCO3 to 40g of Mg-powder (<200 mesh) instead of 60g of SrCO3 to 50g of Mg-powder (<50 mesh).

The measurements reported here are a continuation of tropospheric radiocarbon measurements in carbon dioxide carried out since 1961 at our China Lake, California collection facility. The data show a continued decrease in radiocarbon activity from ca 330‰ in 1977 to 215‰ in 1983 in agreement with similar analyses in Europe for the same time interval.

The Mesolithic-Neolithic transition in the wetland margins of the southern North Sea basin occurred well over a millennium after the transition in neighboring loess regions. This article investigates the possible role of hydrological dynamics in the presence of the last hunter-gatherer-fishermen in these wetland regions. A Bayesian modeling approach is used to integrate stratigraphic information and radiocarbon dates both from accurately datable archaeological remains and key horizons in peat sequences in the Scheldt floodplain of northwestern Belgium. This study tests whether the Swifterbant occupation of the study area was contemporaneous with hiatuses in peat growth caused by organic clastic sedimentation due to increased tidal influences and local groundwater rise. The results suggest that the appearance of this culture followed shortly after the emergence of a brackish tidal mudflat landscape replacing a freshwater marsh.

Data on the emergence of pottery and agriculture in Eurasia were analyzed from the view of their spatiotemporal relationship. It was found that there are 2 major types of association between pottery and agriculture: 1) East Asian, with pottery as the main criterion of the Neolithization; and 2) Levantine, with agriculture as the phenomenon most closely related to the emergence of the Neolithic. Some regions of Eurasia have intermediate characteristics. The concept of a single area for pottery origin in eastern Eurasia and its subsequent spread to the west, still used by some scholars, is the revival of the old diffusionist paradigm and does not seem to advance the analysis of the Neolithization process. If the wheat/barley agriculture definitely originated in the Levantine “core” and spread toward Anatolia and central/western Europe, it is impossible to apply the same approach to pottery. The latest developments in chronology of the earliest ceramics in China, one of the key regions in the world in terms of the origin of pottery-making, are critically evaluated.

We made preliminary AMS measurements of 41Ca/Ca ratios in bone and limestone specimens with the Argonne Tandem-Linac Accelerator System (ATLAS). We were able to avoid pre-enrichment of 41Ca used in previous experiments due to a substantial increase in Ca-beam intensity. Most of the measured ratios lie in the 10-14 range, with a few values below 10-14. In general, these values are higher than the ones observed by the AMS group at the University of Pennsylvania. We discuss possible implications of these results. We also present the current status of half-life measurements of 41Ca and discuss 41Ca production processes on earth.

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.

Chemical preservatives (e.g. mercuric chloride) are routinely added to freshwater samples to prevent biological activity compromising the isotopic signature of dissolved organic matter (DOM) with time. However, alternative preservation methods are needed due to regulations restricting the use of preservatives with potentially adverse environmental and health impacts, rendering such additions unviable. This study investigates whether a non-chemical storage method is sufficient to maintain the radiocarbon and stable carbon and nitrogen signatures of freshwater DOM from a low order river system draining a peaty catchment. Some 50 L of stream water were collected in 1 plastic carbuoy and, within 24 hr, 1-L aliquots were transferred to acid-washed plastic bottles. Five aliquots were analyzed immediately to determine the baseline values for 14C (pMC), δ13C (VPDB‰), δ15N (AIR‰), %C (mg L–1), and %N (mg L–1). Of the remaining subsamples, 20 were frozen and a further 20 refrigerated at <4 °C. After 7, 30, 90, and 180 days, 5 frozen and 5 refrigerated aliquots were analyzed in the same manner as the baseline aliquots. Analysis of the results shows that there is no statistically significant interaction between the variables storage method or length of storage for any of the determinants. Storage method has a statistically significant effect on 14C (pMC) and [C] (mg L–1). Length of storage has a statistically significant effect on δ13C (VPDB‰), [C] (mg L–1), and [N] (mg L–1) values. Neither storage method nor length of storage appear to have a statistically significant effect on 815N (AIR‰) values.

The addition of organic materials derived from the upper soil layer yields, for samples at greater depth, younger 14C dates than the date of deposition. To find a criterion for the contamination with younger carbon in a soil sample, we examined the radiocarbon concentrations in two humic acid fractions and humin taken from the same sample. The humic acid extracted from a soil sample was divided into two fractions HA1 and HA2. HA1 is the first fraction extracted by 30 minutes' heating with 2 percent NaOH solution, and HA2 is the second fraction extracted by 2 hours' heating with 2 percent NaOH solution after the extraction of HA1. The residue was assumed as the humin (HM).

Many of the peat or soil samples taken from the layer just above the nonpermeable layer contain appreciable amounts of organic materials transported from the upper layer after the sedimentation of the deposits. For the limited number of cases tested here, there is a trend in which the contaminants are selectively extracted by HA1 or HA2. When the soil samples are contaminated the ages of the HA1 and HA2 fractions appeared to differ widely in most cases. Agreement between the HA1, HA2, and HM ages may be used as a criterion for the reliability of the soil dating.

Two sediment sequences from Big Kyzykul Lake and the Shushenskoe paleolake in the Minusinsk depression, Southern Siberia, were studied by pollen, microfossil, and geochemical analyses, as well as radiocarbon dating. The records indicate the persistence of an arid period between ∼11.7–7.6 cal kyr BP, increased effective moisture since ∼7.6 cal kyr BP, 2 humid impulses at ∼5.1 and 2.8 cal kyr BP separated by a dry interval, and the return to generally drier conditions after ∼1.5 cal kyr BP. This is contrary to the findings noted for the Eurasian temperate zone, but agrees with proxy data reported for arid and semi-arid zones of Central Asia. Reconstructed changes in climate and environment are in good agreement with archaeological data. Almost no evidence of the Mesolithic-Neolithic cultures has been reported for the depression, which is consistent with a dry early and mid-Holocene. Effective moisture started to rise from ∼7.6 cal kyr BP, followed by the beginning of human occupation at ∼6 cal kyr BP. Two maxima of humidity are recorded in the late Holocene, corresponding to the arrival of trees in the depression. No gap was to be found from the Early Bronze to the Iron ages cultures at this time, with the exception of a dry interval at ∼3.6–3.3 cal kyr BP, when the Minusinsk depression was sparsely occupied. The data obtained suggest a close relationship between climate change and cultural dynamics in the steppe zone of Southern Siberia.

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.

On behalf of the organising committee, it is a great pleasure to welcome you all to this 14C workshop and indeed to Scotland. The organising committee has already indicated its ability by arranging sunshine for a place and time in which horizontal rain is more common. We plan to build on this initial success by having an outstanding week of good science and pleasant social activity. Scientifically, we have the opportunity firstly to look back and review previous research on the accuracy and precision of 14C dates. Then we will hear and discuss some important new results from the final stage of the present international intercomparison study. Finally, we will discuss and plan mechanisms and procedures by which, in future, we can improve our general level of performance. Paralleling this and of equal if not more importance, we have arranged a social programme which we hope will give us the opportunity to eat and drink well together, see some of the country, get to know each other better and discuss our science informally. So our hopes are high and our welcome sincere.

Progress in radiocarbon accelerator mass spectrometry (AMS) techniques enables much more access to wiggle-matching techniques for high-precision 14C dating with relatively low costs than before. Recently, we have applied wiggle-matching for a number of wood samples where dendrochronology is difficult because of various limitations imposed for dendro-dating. In most cases, wiggle-matching gave rather unambiguous calendar ages, but we found that in some cases the calibrated date was very sensitive to a systematic error of the 14C date. Here, we present a wooden artifact from the Ujishigai archaeological site as a case where the highest wiggle-matched date did not agree with the date given by dendrochronology. An age with lower probability agreed with the tree-ring age of AD 389, which marked the beginning of the production of Sue ware (unglazed stoneware) in Japan. We show that systematic errors must be carefully taken into account while interpreting 14C wiggle-matching results, whether they are due to instrumental errors (statistical) or due to a regional offset from the IntCal04 (Reimer et al. 2004) calibration curve.

We present a new method developed for measuring radiocarbon of methane (14CH4) in ancient air samples extracted from glacial ice and dating 11,000–15,000 calendar years before present. The small size (∼20 μg CH4 carbon), low CH4 concentrations ([CH4], 400–800 parts per billion [ppb]), high carbon monoxide concentrations ([CO]), and low 14C activity of the samples created unusually high risks of contamination by extraneous carbon. Up to 2500 ppb CO in the air samples was quantitatively removed using the Sofnocat reagent. 14C procedural blanks were greatly reduced through the construction of a new CH4 conversion line utilizing platinized quartz wool for CH4 combustion and the use of an ultra-high-purity iron catalyst for graphitization. The amount and 14C activity of extraneous carbon added in the new CH4 conversion line were determined to be 0.23 ± 0.16 μg and 23.57 ± 16.22 pMC, respectively. The amount of modern (100 pMC) carbon added during the graphitization step has been reduced to 0.03 μg. The overall procedural blank for all stages of sample handling was 0.75 ± 0.38 pMC for ∼20-μg, 14C-free air samples with [CH4] of 500 ppb. Duration of the graphitization reactions for small (<25 μg C) samples was greatly reduced and reaction yields improved through more efficient water vapor trapping and the use of a new iron catalyst with higher surface area. 14C corrections for each step of sample handling have been determined. The resulting overall 14CH4 uncertainties for the ancient air samples are ∼1.0 pMC.