A new set of radiocarbon dates from a rockshelter in Mendoza, Argentina addresses the question of the temporal overlap between the presence of an unidentified extinct ground sloth (cf., Mylodontidae) and evidence of human activity. Dung balls on the cave floor, evidently deposited by sloth, are overlain by charcoal, apparently of cultural origin. 14C dates, mostly on charcoal and dung from this shelter, calibrated using recently published curves, as well as the stratigraphy of the deposits from which the samples were collected, suggest that any co-occurrence of humans and ground sloths in this region was brief. In contrast, the single date on mylodon dermal ossicles from this shelter suggests significant time overlap. Replication of this date as well as obtaining new high-precision 14C analyses from this site will be the next priority.

Two methods of assigning probability values to calendar years are compared by summing distributions for a large number of 14C ages derived from samples initially distributed uniformly in calendar years. The radiocarbon ages are calibrated with both a hypothetical calibration curve and the internationally accepted one. The effect of the calibration curve on an ideal and a random sample population is examined.

Buran-Kaya III is a rockshelter located in Crimea (Ukraine). It provides an exceptional stratigraphic sequence extending from the Middle Paleolithic to the Neolithic. Nine Paleolithic layers have been attributed to the Streletskaya or eastern Szeletian, Micoquian, Aurignacian, Gravettian, and Swiderian cultural traditions. Human remains from the richest Gravettian layer (6-1) are radiocarbon dated to 31.9 ka BP, and therefore represent, with Peştera cu Oase (Romania), one of the oldest anatomically modern humans in Europe. The aim of this study is to obtain a controlled stratigraphic sequence of Buran-Kaya III with new 14C dates from faunal and human bones, in their paleoenvironmental context. During our new excavations (2009–2011), sediments, bones, and teeth from the stratigraphical layers were sampled for sedimentological, geochemical, and 14C analyses. Fossil bones from the 2001 excavations were also analyzed. Accelerator mass spectrometry (AMS) 14C dating, including cross-dating, was performed at Groningen, Saclay/Gif-sur-Yvette, and Oxford. Biogeochemical analysis was used to test the integrity of the bone collagen. Dates were modeled using a Bayesian approach. The sedimentological, paleoenvironmental, and chronological data are mutually consistent and show that the Paleolithic human occupations at Buran-Kaya III range from the end of MIS 3 to early MIS 1. These results provide a new chronological and paleoenvironmental framework for the human settlements in eastern Europe during the late Middle and the Upper Paleolithic.

We conducted analyses to identify the most suitable bone pretreatment protocol to be used by the recently established Radiocarbon Laboratory at the University of Cologne, CologneAMS. In 2 sets of analyses, we determined 14C ages for subsamples taken from 3 14C bone standards (Oxford Mammoth, VIRI I, and VIRI H) complemented by age determinations of 12 unknown bone samples. Our results suggest that the strength and duration of the acid and alkali steps and the temperature of gelatinization might have a larger influence on the obtained ages than the presence or absence of ultrafiltration as a pretreatment step.

The purpose of this paper is to present the methodology used for sample preparation at the Woods Hole Oceanographic Institution Radiocarbon Laboratory. The WHOI lab is dedicated to oceanographic research supported by the National Science Foundation (OCE81-11954). We began operation in March 1982. The methods used for the production of samples are based on those developed previously (Barker, 1953; Suess, 1954; Noakes, Kim, & Stipp, 1969; Linick, 1975). Subsequent changes and refinements to these methods are described. This paper will present detailed descriptions of how various samples are collected and sectioned, then converted to CO2 and to C2H2, the primary counting gas for most of our samples.

Efforts to extract weak geomagnetic excursion signals from Chinese loess-paleosol 10Be have generally been unsuccessful due to the complexities of its accumulation, because the geomagnetic and climate (precipitation and dust) signals contained in loess-paleosol sequence are tightly overprinted. Here, we present a reconstruction of geomagnetic relative paleointensities for the past 130 kyr from 10Be records in 2 Chinese loess-paleosol sections using a correction based on the correlation of 10Be with magnetic susceptibility (SUS) to remove the climatic contamination. Both these records reveal the Laschamp and Blake events, which lie in the loess and paleosol (L1SS1 and S1SS3) horizons corresponding to mid-MIS 3 and 5e, respectively. The good agreement between our results and other geomagnetic intensities reconstructions from Atlantic and Pacific sediments indicates that our method is robust. Our study suggests the potential application of loess-paleosol 10Be for reconstructing geomagnetic intensity variations spanning the whole Quaternary.

The C14 measurements reported here were made in this laboratory between October 1968 and October 1969.

The Balearic Islands are one of the most widely dated regions in Europe, totaling about 800 dates. The aim of this paper is to propose an updated periodization for the prehistory of Majorca and Minorca based on the analysis of a series of absolute dates for over 100 archaeological sites and in combination with a critical assessment of the associated contextual information. Only by means of a solid chronological scheme will we then be able to approach research into the social significance of the vast archaeological record that the islands has to offer and also make reliable comparisons with developments in surrounding regions.

The present date list contains only details of C14 measurements on sites selected for archaeomagnetic study. Except where otherwise stated in the text, all samples were collected in 1970 or 1971 during fieldwork by one of the authors (M.B.), and were pretreated with hot 2N HCl to remove any possible contamination by pedogenic carbonate. Benzene samples were prepared using updated synthesis techniques (Polach et al., 1972) and measurements of C14 activity were made on two Beckman LS-200 liquid scintillation spectrometers following automatic cycling procedures described previously (Polach, 1969). Samples ANU-677-697 were counted on the spectrometer which has been in use since 1968 (LS-1).

A review of recently published temporal data from Shuidonggou Locality 1 indicates that a 40–43 cal ka date for the inception of Initial Upper Paleolithic (IUP) blade-oriented technologies in East Asia is warranted. Comparison of the dates from Shuidonggou to other Asian IUP dates in Korea, Siberia, and Mongolia supports this assertion, indicating that the initial appearance of the IUP in East Asia generally corresponds in time to the fluorescence of the IUP in eastern Europe and western Asia. This conclusion preliminarily suggests that either a version of the IUP originated independently in East Asia just prior to 40 cal ka, or more likely, that an early, initial diffusion of the IUP into East Asia occurred ∼41 cal ka, a hypothesis consistent with current estimates for the evolution or arrival of modern humans in the region.

The Radiocarbon Dating Laboratory of the Institute was established in 1974 primarily to assist in the program of research undertaken by the Institute's Department of Quaternary Palynology (Rajagopalan and Vishnu-Mittre, 1977). The measurements carried out by the Laboratory up to December 1977 are presented in this date list.

Samples of sediment cores from two lakes in the karst area of northwest Yugoslavia were analyzed. Both Lakes Kozjak and Prošće are in the Plitvice National Park, Central Croatia. 14C dating, sedimentologic, seismic, and isotopic studies, and distribution of diatoms are presented.

14C dating of lake marl revealed a uniforn sedimentation rate in Lake Prošće as opposed to Lake Kozjak. Both lake sediments belong to the Holocene period. 14C dating of lake sediment is in agreement with seismic profiles, sedimentologic analysis, and diatom frequency measurements both in an undisturbed as well as in a disturbed lake sediment.

AMS 14C measurements on samples collected in the tropical-equatorial Indian Ocean during the INDIGO program (leg II, 1986) are presented and compared with β-counting results obtained under both INDIGO program and GEOSECS expedition in the Indian Ocean (1978). The most significant observation is a doubling of the bomb-14C inventory and mean penetration depth in the equatorial zone. Based on hydrologic considerations, two hypotheses can be proposed: 1) direct influx of Pacific mid-latitude waters through the Indonesian archipelago and 2) advection and/or mixing with Mode Water from the southern gyre of the Indian Ocean. Results obtained with a general circulation model of the ocean suggest that the influx from the Pacific is important in the upper 300m and that below 500m the bomb-14C budget is dominated by Mode Water advection.

The first series of radiocarbon dating measurements made at the British Museum Research Laboratory are reported in the following list. The report covers a period during which two instances of radioactive contamination occurred to interrupt dating work, and is consequently a short one.

Most of the 14C measurements reported here were made between October 1973 and October 1974. Equipment, measurement, and treatment of samples are the same as reported previously (R, 1968, v 10, p 36–37; 1970, v 12, p 534).

Coral skeletal radiocarbon records reflect seawater ∆14C and are useful for reconstructing the history of water mass movement and ventilation in the tropical oceans. Here, we reconstructed the inter-annual variability in central equatorial Pacific surface water ∆14C from 1922–1956 using near-monthly 14C measurements in a Porites sp. coral skeleton (FI5A) from the windward side of Fanning Island (3°54′32′′N, 159°18'88′′W). The most pronounced feature in this record is a large, positive shift in the ∆14C between 1947 and 1956 that coincides with the switch of the Pacific Decadal Oscillation (PDO) from a positive to a negative phase in the mid-1940s. Although the absolute ∆14C values from 1950–1955 in FI5A differ from the ∆14C values of another coral core collected from the opposite side of the island, both records show a large, positive shift in their ∆14C records at that time. The relative increase in the ∆14C of each record is consistent with the premise that a common mechanism is controlling the ∆14C records within each coral record. Overall, the Fanning ∆14C data support the notion that a significant amount of subtropical seawater is arriving at the Equator, but does not allow us to determine the mechanism for its transport.

The radiocarbon content of Japanese cedars was measured by accelerator mass spectrometry for decadal tree-ring samples from the period of 240 BC to AD 900. Conventional gas counting was also used for part of the samples. The data were compared with the INTCAL98 calibration curve (Stuiver et al. 1998). The results indicate that the difference in atmospheric 14C between Japan and North America or Europe is negligible at this period, less than 18 14C yr using an average of 50 yr. However, in the period of about AD 100 to about AD 200, we cannot exclude the possibility of a deviation of the order of 30 to 40 14C yr to the older ages.

This article presents radiocarbon data for known-age, pre-bomb marine gastropods, Busycon sinistrum and Strombus alatus, collected between AD 1924 and 1946 from nearshore environments of the Florida Panhandle, on the northern Gulf of Mexico. Δ14C was measured in whole crushed juvenile specimens (n = 7) and terminal edges of adult specimens (n = 6). A subsample of adult specimens (n = 3) was subjected to additional, intrashell sampling to observe short-term variability in 14C conditions. Δ14C values were consistent within and among B. sinistrum specimens, and we propose a reservoir age offset (ΔR) of −9 ± 25 14C yr for B. sinistrum from the northwest coast of Florida. S. alatus shells exhibited significant variability from one individual to another, and also within individual specimens. ΔR values for S. alatus range from −3 ± 30 to 659 ± 30 14C yr. These differences may result from a combination of factors, including subregional variability in inputs of 14C-depleted waters and life-history factors including mobility, mode of feeding, and ontogenetic niche shifts.

We report compound-specific radiocarbon analyses of organic matter in ocean sediments from the northeast Pacific Ocean. Chemical extractions and a preparative capillary gas chromatograph (PCGC) were used to isolate phospholipid fatty acids (PLFA) and n-alkanes from 3 cores collected off the coast of California, USA. Mass of samples for accelerator mass spectrometry (AMS) 14C analysis ranged from 13–100 μg C. PLFA extracted from anaerobic sediments in the Santa Barbara Basin (595 m depth) had modern Δ14C values (–20 to +54‰), indicating bacterial utilization of surface-produced, post-bomb organic matter. Lower Δ14C values were obtained for n-alkanes and PLFA from coast (92 m depth) and continental slope (1866 m) sediments, which reflect sources of old organic matter and bioturbation. We present a brief analysis of the blank carbon introduced to samples during chemical processing and PCGC isolation.

We determined δ13C and D14C in some agricultural soil profiles of the tropics: Ustalf from the semi-arid tropics (India), a Udult, an Aquoll and an Aquept from the humid tropics (Philippines). We used a thin-layer sampling, resulting in high-resolution depth-distribution patterns of natural 13C and 14C content of organic carbon. Regular plowing or puddling leads to uniform isotope concentrations in the topsoil. Decomposition of organic matter raises the δ13C value, and vertical translocation raises the δ13C value with depth. The change of cultivation from pulses (C3-type metabolism of photosynthesis) to sorghum (C4) results in a decrease of δ13C with depth in the topsoil. Where the clay content in the subsoil is high, δ13C remains constant, due to fixation of organic carbon to clay minerals, and D14C decreases with depth. Below the clay-enriched zone, δ13C declines and D14C rises again, due to a chromatographic-like effect. At some horizon boundaries, inhomogeneities in texture delay percolation locally, thus preventing sorption and causing peak values of D14C.