The archaeology of radiocarbon accelerator dating

Accelerator mass spectrometry (AMS) allows radiocarbon dating to be carried out by direct counting of¹⁴C atoms, rather than the conventional counting of radioactive disintegrations. The result is that samples up to 1000 times smaller can be handled. The approach was tested in principle by 1977 and for archaeological operation by 1983. More than 2000 samples per year are now being dated worldwide. The machines can now operate to about ± 80 years or better. Dates older than 40,000 years have not yet been achieved, but the ability to use small samples has already had considerable impact on dating the period 10,000–30,000 years ago. Bone is an ideal material for the new technique, since amino acids can normally be isolated and purified from gram-size samples. Studies of the origins of domestication are aided by the dating of individual grains and seeds. Because small samples can be mobile in the soil, careful sample selection strategies and procedures are required. The full impact of the technique can be assessed only through the rapid and comprehensive publication of archaeological results.     

Radiocarbon Chronology of the Siberian Paleolithic

We have compiled 462 C-14 determinations for 120 Paleolithic and Mesolithic sites from Siberia and the Russian Far East. The Mousterian sites are dated to ca. 46,000–28,500 BP. The Middle–Upper Paleolithic transition dates to ca. 43,300–28,500 BP. Although there are a few earlier sites, most of the Upper Paleolithic sites are dated to the time interval between ca. 34,000 BP and 10,000 BP. The earlier Upper Paleolithic stage is characterized by macroblade technology and is radiocarbon-dated to ca. 34,000–20,000 BP. The earliest microblade technology occurs in the late stage of the Upper Paleolithic, dated to ca. 23,000–20,000 BP, but the majority of microblade sites is dated to ca. 20,000–11,000 BP. The Final Paleolithic (Mesolithic) sites date to ca. 12,000–6000 BP. At ca. 13,000–11,000 BP, the earliest Neolithic appeared in both the Russian Far East (Amur River basin) and the Transbaikal. The Paleolithic–Neolithic transition occurred ca. 13,000–6000 BP.     

The Unitary Association Method of Relative Dating and Its Application to Archaeological Data

The primary objective of relative dating techniques is to determine a reliable sequence of archaeological deposits. This task becomes more difficult whenever our research steps beyond individual sites to the study of intercommunity relationships because we need to develop some means of associating unconnected deposits in time. Radiocarbon dating, as a stand-alone method, cannot always be used to draw reliable correlations between sites. The relevance of archaeological dates, including absolute dates, relies ultimately on the determination of artifact or sample associations and their respective superpositional relationships. The Unitary Association Method of Relative Dating is an alternative to seriation methods that is less susceptible to spatial variation and offers analytical strengths needed for regional chronological analyses.     

Improvements in Archaeomagnetic Dating in Western Europe from the Late Bronze to the Late Iron Ages: An Alternative to the Problem of the Hallstattian Radiocarbon Plateau

We present a new curve of the directional secular variation of the geomagnetic field in Western Europe between 1500 bce and 200 ce . Its computation relies on a Bayesian framework. The fast secular variation during the Late Bronze and Early Iron Ages makes archaeomagnetic dating efficient with a respective precision of 150–200 and 60–100 years during these periods. The Bayesian method also provides posterior date distributions that refine the dating of reference data, especially during the period of the Hallstattian radiocarbon plateau. Archaeomagnetism becomes a valuable alternative to radiocarbon and will help to improve the archaeological chronologies.     

Contemplating the history and future of radiocarbon dating in the American Southeast

We consider the history, present, and future of radiocarbon dating in the American Southeast. We point out some of the past and present flaws related to archaeological research and dating. Our approach to this review is rooted in the perspective that each radiocarbon date collectively adds to our knowledge of the region and not just a particular site. Based on our observations, we suggest some “good” practices with respect to certain aspects of radiocarbon dating. Our concluding discussion considers Bayesian chronological analysis and the growing contribution of chronological modeling to the Southeast.     

A Spanish Man‐o‐War in New Zealand? The 1864 wreck of Grafton and its lessons for pre‐Cook shipwreck claims

This paper considers the 1864 wreck of Grafton in the Auckland Islands, and its implications for wreck analysis and pre‐Cook exploration claims. The captain of Grafton, Thomas Musgrave, stated that the schooner was built from the wreck of a Spanish man‐o‐war, and archaeological analysis of the wreck found that the timbers are a tropical South American species, and had possibly been reused. The implications of this are clear; it is possible that timbers that originated in pre‐Cook (1769) ships lie in New Zealand, but without a full understanding of the historical and archaeological context of any such timbers, including their reuse in later ships, it is not possible to claim proof of pre‐Cook European exploration of New Zealand.     

14C and Maya Long Count Dates: Using Bayesian Modelling to Develop Robust Site Chronologies

Bayesian statistics has now demonstrated its strong utility in archaeology, specifically through software that conditions radiocarbon data. Only recently has this technology been applied within Maya archaeology, however, in part because the Maya calendar provides a much greater resolution in dating archaeological events than is possible with radiocarbon data. The Long Count in particular allows for the assignment of some events relative to each other, accurate to the day. In this paper, a new approach is presented to incorporate robust records of both in the same Bayesian analysis through the OxCal software. The results do call for a reconsideration of the earliest radiocarbon studies in the Maya area from the 1960s, as well as the latest attempts to corroborate the currently popular calendar correlation known as the GMT. This new study demonstrates the value of the approach and corroborates the 1σ accuracy of the GMT, while at the same time opening up the possibility of revision by 20 or more years.     

The Comings and Goings of Sheep and Pottery in the Coastal Desert of Namaqualand,South Africa

This paper evaluates chronological trends in the presence and absence of domestic animal bone (sheep, goat, and cattle) and pottery in Namaqualand, the proposed gateway to the rest of South Africa for early herders or hunter-gatherers with sheep and ceramics. We update date calibrations with local ΔR corrections and mixtures of recent calibration curves and include five previously unpublished dates. We use histograms of calibrated medians, sorted in 100-year bins, to assess sustained regional patterns with dates associated with domestic animal bone and pottery (n = 73). While too small to be useful as a population proxy, the current set of dates does reveal three pulses of occupation separated by two clear gaps, which we evaluate with a Bayesian model of three sequential phases. The model's boundaries are used as estimates of the dates of Early (AD 80–210), Middle (AD 490–790), and Late (AD 1180–1690) occupational phases separated by two substantial lapses of 280 and 380 years, respectively. The alternating phases of presence and absence are suggestively correlated with climate shifts, leading to a discussion of the idea that effective moisture was a crucial factor in choosing whether to occupy Namaqualand. The set of archaeological dates has greater temporal and spatial resolution than many regional climate data, so we suggest that these trends may more accurately reflect the variable conditions specific to Namaqualand, at least until they are refined by future climate research.