The continuing improvements in accelerator mass spectrometry (AMS) dating technology mean that it is possible to work on ever smaller samples, which in turn, make an ever wider range of sample potentially available for dating. This paper discusses some of the difficulties arising with the interpretation of AMS dates obtained from carbon in iron. The overriding problem is that the carbon, now in chemical combination with the iron, could have come from a variety of sources with very different origins. These are now potentially an irresolvable mixture in the iron. For iron made over the last millennium, there are the additional problems associated with the use of both fossil fuel and biomass fuel in different stages of the iron making, leading to great confusion, especially with authenticity studies.

Pearl shell was an important and highly valued resource for producing tools and ornaments in Oceania. One pearl shell artifact type that is quite rare in Micronesia, however, is the crescent-shaped scraper/grater. These artifacts have recently been found in 2 burial caves in Palau, Western Caroline Islands, suggesting they may have played important social and symbolic roles in society. The first direct accelerator mass spectrometry (AMS) dating of this tool type, found in association with in-situ female burial at the Chelechol ra Orrak site, provides a date of AD 150-270, while associated dates range from 770 BC-AD 180. These dates help contextualize human burials and associated artifacts from one of the earliest and most diverse burial sites in Austronesia.

The first meeting of the IntCal04 working group took place at Queen's University Belfast from April 15 to 17, 2002. The participants are listed as co-authors of this report. The meeting considered criteria for the acceptance of data into the next official calibration dataset, the importance of including reliable estimates of uncertainty in both the radiocarbon ages and the cal ages, and potential methods for combining datasets. This preliminary report summarizes the criteria that were discussed, but does not yet give specific recommendations for inclusion or exclusion of individual datasets.

Existing data and theory do not support a recent assertion that upwelling of old carbon has led to systematically 100-300 yr too old radiocarbon ages for the Mediterranean region. Similarly, the prehistoric tree-ring record produced over 3 decades by the Aegean Dendrochronology Project is shown to provide robust, well-replicated data, contrary to a recent unfounded assertion. 14C and dendrochronology provide an accurate and precise chronometric framework for the Mediterranean region.

Radiocarbon ages of calcium oxalate that occurs naturally on rock surfaces have been used recently in archaeological and paleoenvironmental studies. Oxalate rock coatings are found globally, with most appearing to be residues from epilithic lichens. To explore the source(s) of carbon used by these organisms for the production of oxalate we measured the natural abundances of 14C and 13C in 5 oxalate-producing lichen species, 3 growing on limestone in southwestern Texas and 2 on sandstone in Arkansas. We also examined the distribution of the isotopes between the calcium oxalate and lichen tissues by separating these components and measuring the 13C/C independently. The results demonstrate that the limestone species were slightly enriched in 14C, by 1.7 per mil, relative to the sandstone species, which suggests that "dead" carbon from the limestone substrate does not constitute a significant source of carbon for the production of oxalate. The calcium oxalate produced by the lichens is also enriched in 13C by 6.5 per mil compared to the lichen tissues, demonstrating that there is a large carbon isotope discrimination during oxalate biosynthesis. These results support the reliability of 14C ages of calcium oxalate rock coatings used for archaeological and paleoclimate studies.

The University of Waikato, Hamilton, New Zealand and the Queen's University of Belfast, Northern Ireland radiocarbon dating laboratories have undertaken a series of high-precision measurements on decadal samples of dendrochronologically dated oak (Quercus petraea) from Great Britain and cedar (Libocedrus bidwillii) and silver pine (Lagarostrobos colensoi) from New Zealand. The results show an average hemispheric offset over the 900 yr of measurement of 40 +/13 yr. This value is not constant but varies with a periodicity of about 130 yr. The Northern Hemisphere measurements confirm the validity of the Pearson et al. (1986) calibration dataset.

The authors study the radiocarbon dating of a relic believed to be the tablet that was placed on the cross of Jesus Christ at the time of his crucifixion.