The Pre-Pottery Neolithic B (PPNB) site of Yiftahel, Israel, contains abundant plaster floors. We surveyed the states of preservation of the plasters using an infrared spectroscopic assay that characterizes the extent of disorder of the atoms in the calcite crystal lattice. We identified the 3 best-preserved plaster samples that had disorder signatures most similar to modern plaster. We then studied the surface layers, fine-grained matrices, and large aggregates of these samples using micromorphology, Fourier transform infrared (FTIR) microscopy, stable carbon and radiocarbon concentrations. Even though some of the plaster components have a geogenic appearance in micromorphology slides and in FTIR spectra, the 14C analyses show that all components were exposed to high temperatures and as a result were equilibrated with the 14C content of the atmosphere ∼10,000 yr ago. This implies that the plasters at Yiftahel were produced entirely from heat-altered calcite. We also show that these plasters have undergone significant diagenesis. The plaster component with the most disordered atomic signature, and hence the most similar in this respect to modern plaster, did indeed produce a 14C date close to the expected age.

The Vinland Map, drawn on a 27.8 × 41.0 cm parchment bifolium, is housed in the Beinecke Rare Book and Manuscript Library at Yale University. In the northwest Atlantic Ocean, it shows “the Island of Vinland, discovered by Bjarni and Leif in company.” Skelton, Marston, and Painter (Skelton et al. 1965, 1995) firmly argued the map's authenticity, associating it with the Council of Basle (AD 1431–1449), that is, half a century before Columbus's voyage. Nevertheless, vigorous scholarly questioning of the map's authenticity has persisted (Washburn 1966; McCrone 1974; Olin and Towe 1976; Cahill et al. 1987; McCrone 1988; Towe 1990). We have determined the precise radiocarbon age of the map's parchment by accelerator mass spectrometry (AMS). The one-sigma calibrated calendrical date range is AD 1434 ± 11 years: the 95% confidence level age range is AD 1411–1468.

The natural 14C and 13C content of soil organic matter and their dependence on depth for two Alfisols are presented. This soil type which covers a large area of the earth's surface is characterized by clay migration processes (“Lessivé”). The samples were taken as successive horizontal layers of 2cm depth from an area of ca lm2 size as deep as the C content allows 14C analysis. The minima of the D14C distribution decrease with depth, while the maxima increase in the upper, leached horizon (A1) due to bomb 14C and decrease in the lower, clay illuviated (Bt). δ13C indicates proceeding decomposition in A1 and protection of carbon, probably due to the formation of clay humus complexes in Bt. δ13C values were also used for age correction of the 14C data due to isotopic fractionation. The D14C and δ13C depth distributions are characterized by sharp peaks at the boundaries of the horizons, probably caused by the influence of textural changes on the transport of C with percolating water.

This list includes dates measured from January 1974 to June 1975 with previously described CO2 proportional counters (Alessio et al, 1970b). All archaeologic and geologic samples except for Arslantepe series come from Italian territory. Chemical apparatus for CO2 preparation and purification is unchanged (Alessio et al, 1970b). Data recording devices have recently been replaced with integrated circuits built entirely at the Lab. The logic of the circuitry was also modified to provide more stable devices and a higher relative figure of merit A/√B of each counter (A = net activity of modern standard, B = background). Consequently, the resolution of age measurements has increased appreciably. Present values of A/√B for the 4 counters in use are shown in Table 1.

Extracting a series of amino acids from fossil “collagen” makes it possible to compare chemically well-characterized molecules from one bone sample, both chemically and by isotopic analysis. Thus, the integrity of collagen samples and possible contamination can be checked. We describe the routine high-performance liquid chromatographic extraction of five amino acids: glycine, hydroxyproline, glutamate, threonine and alanine. Humates are eliminated during the extraction, which can be monitored continuously.

A PC-based computer program for automatic calibration of 14C dates has been developed in Turbo-Pascal (version 4.0). It transforms the Gaussian 14C dating result on the 3σ level into a real calendar age distribution. It uses as a calibration curve a spline function, generated along the calibration data points as published in the Radiocarbon Calibration Issue. Special versions of the code can average several 14C dates into one calibrated result, generate smoothed curves by a moving average procedure and perform wiggle matching.

The National Electrostatics Corporation has built and tested a prototype low energy, open-air, single stage carbon accelerator mass spectrometry (AMS) system (patent pending). The configuration tested has a standard 40-sample, multi-cathode SNICS source on a 300-kV deck. The beam is mass analyzed before acceleration to a gas stripper located at ground. The 14C+ ions are separated from 13C+ and 12C+ arising from the molecular breakup by a 90° analyzing magnet immediately after the gas stripper which acts as a molecular dissociator. The 14C+ beam passes through an electrostatic spherical analyzer before entering the particle detector. The observed 14C/12C precision is better than 5% with a sensitivity of better than 0.05 dpm/gmC. A first single stage AMS system has been ordered. The configuration of this system will be discussed.

The dates and activity measurements given below have been obtained during the year 1960 (excepting only Q-9 held over from the previous year). They have been made with carbon dioxide at 3 atmospheres pressure in a proportional gas-counter similar to that used for the results given in Radiocarbon Supplement, volumes 1 and 2.

We used direct radiocarbon dates of peat samples, pollen dates and land-uplift chronology from >1300 cores comprising all or most of the Holocene in the boreal region of Finland, Estonia and Maine (USA) to obtain long-term carbon accumulation rates for boreal peatlands. The “apparent” long-term rate of carbon accumulation (LORCA; g C m−2 a−1) ranged from 4.6 to 85.8 (mean 19.9 ± 10.7), depending on the geographical location, wetland type and the age of the mire. The “true” or “actual” rate of carbon accumulation (ARCA), as derived from models for peatbog growth, was usually ca. 70% of LORCA. We studied the raised bog Reksuo more intensely in terms of growth dynamics, and we report preliminary results of the “three-dimensional” or spatial carbon accumulation rates. These results strongly contradict the concept of constant input and constant decay throughout the millennia. The study emphasizes the importance of exploring the formation and dynamics of entire mire ecosystems, and the role of carbon in these systems, in addition to studying single cores.

14C dating of shells from terrestrial and freshwater mollusks is prone to distortion by post-depositional diagenesis as well as incorporation of material depleted in 14C while the mollusk was alive. Three types of diagenetic change can result: etching, the development of surface crusts, and replacement of aragonite by calcite. Inspection under the light microscope, x-ray diffraction, and scanning electron microscope make it possible to assess the relative importance of the changes. When they are confined to the surface, mechanical cleaning combined with judicious leaching can reduce them to <1% of the total sample. The corresponding errors, which can now be specified, are often no greater than those associated with the statistics of counting.

The dates given have been obtained up to the end of December, 1958. They have been made with carbon dioxide at 2 atmospheres pressure in a proportional counter of about 2-liter volume. For further details of construction and procedure, see Godwin, Walker, and Willis, 1957. The establishment of the project was made possible by a grant from the Trustees of the Nuffield Foundation, whom we are most happy to thank along with the Imperial Smelting Corporation who have lent us the zinc shielding for the gas-counter.

The measurements reported have been carried out during1966 in the Isotope Laboratory of the Institute ofGeophysics and Planetary Physics as a continuationof the UCLA date lists I through V. Samples wereanalyzed as CO2-gas at one atm in a 7.5 Lproportional counter with three energy channels. Theall-solid-state unit is supplied with high voltagefrom a remarkably stable and interference-freebattery source. Radiocarbon ages have beencalculated on the basis of a 5568-yr half-life aswas recommended by the Sixth InternationalC14 and H3 DatingConference, June 1965, in Pullman, Washington. Thestandard for the contemporary biosphere remains as95% of the count rate of NBS oxalic acid forradiocarbon laboratories. Background determinationshave been based on CO2 obtained frommarble. The error listed is always at least aone-sigma statistical counting error. In criticalcases C13/C12 isotope ratiomeasurements were made to correct the dates. Allsamples were subjected to accepted pretreatmentsdiffering in the individual cases to excludecontamination.

To improve the chronology of sediments containing information about Holocene ice shelf and oceanic dynamics in the vicinity of the Antarctic Peninsula, we compare bulk acid-insoluble radiocarbon dating to ramped pyrolysis 14C dating in a sediment core containing ample organic material. This core spans the last 12,000 yr of open-shelf sedimentation in the Bellingshausen Sea, western Antarctic Peninsula. By estimating the spectrum of 14C ages within a given core horizon, the ramped pyrolysis 14C method separates organic carbon relative to thermal stability, isolating younger parts of the mixture from older ones and providing an estimate of the geological uncertainty inherent in a bulk 14C age. Employing the ramped pyrolysis 14C method to this core demonstrates variable bulk 14C age bias and increasing age spectrum downcore, neither of which can be associated with major changes in lithology of the core. The chronology of the sediment core using the youngest ages from the ramped pyrolysis technique allows for correlation between nearby Palmer Deep sediments and these sediments from the Hugo Island Trough.

The Fifth International Radiocarbon Intercomparison (VIRI) continues the tradition of the TIRI (third) and FIRI (fourth) intercomparisons (Scott 2003) and operates as an independent check on laboratory procedures in addition to any within-laboratory procedures for quality assurance. VIRI is a 4-yr project, with the first suite of samples (grain) sent out in September 2004 and the second suite (bone) sent out in December 2005. Further stages will include samples of peat, wood, and shell with a range of ages.

The 4 grain samples included 2 samples (A and C) of barley mash (20 g for radiometric analysis and 2 g for AMS), a grain (barley) byproduct from the manufacture of Glengoyne malt whiskey. The 2 remaining charred grain samples (B and D) were from excavations at Beth Saida and Tel Hadar, respectively (10 g for radiometric analysis and 4 seeds for AMS) and were provided by Elisabetta Boaretto of the Weizmann Institute. Consensus values for samples A and C are 109.2 (standard deviation [1 σ] = 2.73) and 110.6 pMC (1 σ = 2.48), and 2805 (1 σ = 162.7) and 2835 BP (1 σ = 190.8) for samples B and D, respectively. Sample A is a new sample that was collected in 2001, while sample C was used in the FIRI trial as samples G & J (consensus value 110.7 pMC) and was collected in 1998. The expected ages (on archaeological grounds) of samples B and D are 2800 BP and 2850–2900 BP, respectively. The second suite of samples comprises bone, ranging in age from Medieval to “close to background,” and was distributed in December 2005. Samples for both radiometric and AMS laboratories include E: mammoth bone (>5 half-lives); F: horse bone (from Siberia, excavated in 2001); and H, I: whalebone. Finally, sample G (human bone) was only for AMS laboratories. Some of the issues related to using bone in a laboratory intercomparison will be discussed.

Absolute dating of mortars is crucial when trying to pin down construction phases of archaeological sites and historic stone buildings to a certain point in time or to confirm, but possibly also challenge, existing chronologies. To evaluate various sample preparation methods for radiocarbon (14C) dating of mortars as well as to compare different dating methods, i.e. 14C and optically stimulated luminescence (OSL), a mortar dating intercomparison study (MODIS) was set up, exploring existing limits and needs for further research. Four mortar samples were selected and distributed among the participating laboratories: one of which was expected not to present any problem related to the sample preparation methodologies for anthropogenic lime extraction, whereas all others addressed specific known sample preparation issues. Data obtained from the various mortar dating approaches are evaluated relative to the historical framework of the mortar samples and any deviation observed is contextualized to the composition and specific mineralogy of the sampled material.

The limits of the statistical evaluation of 14C dates by histograms are discussed. The method of the attempt to establish a global chronology of the short-term eustatic sea-level changes during the Holocene is examined as well as its correlation with the precisely determined Suess wiggles.

This article outlines the Bayesian models and methods used to facilitate construction of the 2013 internationally agreed radiocarbon calibration curves known as IntCal13, Marine13, and SHCal13. The models build on those used for the 2004 and 2009 estimates of the curves and, as in 2009, arc implemented using Markov chain Monte Carlo sampling, specifically a Metropolis-within-Gibbs sampler. In addition to the data structures accounted for within the 2004 and 2009 models, the approach outlined here also allows for: the presence of additional uncertainty that the data providers have been unable to quantify; tree-ring data that derive their calendar age from wiggle-matching (in addition to ring counting); varve-counted data that exhibit zero increase in calendar age error between 2 or more consecutive layers; and any data source for which we have dependent calendar age uncertainties.

For over 2 decades, there have been calls for Polynesian archaeologists to identify radiocarbon samples to taxon and material type, and preferentially date short-lived materials. This stems from recognition that even modest amounts of inbuilt age are problematic in this oceanic region where human settlement dates to the last 3 millennia or less. Despite programmatic statements to this effect, and empirical demonstrations of value, uptake of these practices has been slow. This article suggests that short-lived materials be defined as those with lifespans of 10 yr or less, recognizing that reducing the distance between target event and the dated material is an ongoing aim for archaeology. We identify both short-lived materials that are suitable for dating and long-lived species (>75 yr) that should be avoided given their potential for inbuilt age. Additionally, we suggest that given the destructive nature of 14C dating there is value to (1) obtain high-resolution photographs of samples prior to analysis, (2) split samples and archive residuals when possible, and (3) routinely report the tools and expertise used in identification. Past and recent dating analyses at a Polynesian site in the southern Cook Islands are used to illustrate how the suggested protocols might enhance current and future studies. We also establish that mature Calophyllum inophyllum, a common coastal tree and valued timber species, has been in the southern Cook Islands for at least the last 700 yr and is likely to be indigenous and long-lived.

C14 measurements reported here were made in this laboratory between December 1, 1961 and October 1, 1962. Sample descriptions are classified as follows:

1. I. Tree-ring dated samples.

2. II. Modern shells from Santa Barbara County, California.

3. III. Archaeologic samples.

4. IV. Palynologic samples.

5. V. Geologic samples.

6. VI. C14 content of caliche.

7. VII. Water samples.

8. VIII. Modern organic sample.

This date list mainly contains results obtained for archaeological samples which were measured in the Groningen laboratory in the course of the years and which have not hitherto been published in a similar form. As such it is an extension of the previous date list (Groningen IV) and reference is made to this publication for information on the method of presentation, the corrections applied, etc. Samples which are primarily of geological significance will be presented separately in next year's list.