Radiocarbon age and depth: a statistical treatment of two sequences of dates from Spain

Two sets of radiocarbon determinations from closely related sites in Valencia procince, Spain, show an increase of age with depth. We explore a model of uniform sedimentation to show this relationship and interpolate the ages of certain cultural events. A weighted least squares regression allows us to consider the variations in both parameters. Testing of this model shows no significant difference from linearity. We suggest some ages for particular cultural events in Valencia province which now need independent confirmation.     

Radiocarbon dates for the late Middle Palaeolithic at Pech de l'Azé IV,France

This paper reports a series of radiocarbon dates on bone samples coming from the Mousterian of Acheulian Tradition (MTA) Layer 3 at the top of the Pech de l'Azé IV (Pech IV, France) Middle Palaeolithic sequence. All of these samples showed evidence of human impact, and they were prepared using current pre-treatment techniques to remove or identify contamination. The results indicate that the MTA at Pech IV started prior to the current limit of radiocarbon calibration (circa 50 ka BP) and ended by 45 ka cal. BP. These dates are supported by additional TL and ESR dates from the sequence, confirm previously suggested correlations between Pech I and IV, and generally fit within the known age range for the MTA. The oldest dates reported here may also lend support to still older TL dates for the MTA that taken together suggest that the MTA extended from late MIS 4 or early OIS 3 through to the end of the Middle Palaeolithic in southwest France.     

Radiocarbon dates as data: quantitative strategies for estimating colonization front speeds and event densities

Archaeological analysis of large-scale prehistoric population history requires us to estimate rates of spatial spread during dispersals, and rates and magnitudes of temporal contraction during crashes. Using OxCal’s MCMC sampling routine, I introduce and demonstrate a simple and easily implemented method of estimating front speeds that takes due account of the uncertainty in the archaeological data (in both dates and distances), and argue that this method is more appropriate than those most often used in front speed estimation at present. I also propose a simple and easily implemented method of estimating event densities as a demographic proxy, as an alternative to summed calibrated probability distributions. I argue that this alternative is a significantly better technique, and show that its use also enables us to identify individual archaeological dates that are exerting particularly strong influence on the results, so that we can efficiently allocate our attention when assessing the possible effects of exogenous sampling uncertainty. To illustrate these methods I re-analyse two published datasets relating to the early Paleoindian colonization of North America. My results with the new technique indicate that even with a very noisy dataset, there was clear evidence in the framework of the INTCAL04 calibration curve for a drastic reduction in archaeological event densities following the Younger Dryas onset, followed by a prolonged period of reduced human activity, and a possible renewed phase of rapid growth after the Younger Dryas termination and onset of the Holocene. However, the revised estimate of the Younger Dryas marine reservoir offset in the INTCAL09 calibration curve for ∼12,550–12,900 cal BP changes the picture significantly, by flattening the peak in Clovis-age events and pushing it forward in time into the early Younger Dryas itself.     

Radiocarbon pottery dating: the chemical compounds of organic fractions, the reliability of 14C dates (preliminary results)

In recent times, a large number of radiocarbon dates appeared for the Southern Neolithic on the basis of pottery dating because other organic matter has practically not been preserved. There are two organic fractions of pottery useful for dating: food residues and carbon from the pottery matrix itself. Food residues are often dated, but this material is not always preserved and is prone to being removed during the cleaning of the pottery. The clay mass of the pottery contains carbon, often directly visible upon breaking of the pottery. The article focusses on determining the chemical composition of the organic fractions in the pottery and the origin of the carbon. For this aim we used the nuclear magnetic resonance (NMR) method to identify the chemical compounds in the food residue and in the pottery matrix. As an example we used pottery from the Neolithic sites: Zamost??e (Central Russia) and the Varfolomeevskay sites (Southern European Russia, Low Volga region) from archaeological collections. The results obtained demonstrate that the food residue and the pottery matrix contain practically the same organic compounds, even if the relative abundances of various compounds are different in these materials. The origin of the carbon from pottery is discussed.     

Radiocarbon Wiggle-Match Dating in the Intertidal Zone

Radiocarbon wiggle-match dating is a technique that can combine the versatility of radiocarbon dating with chronological information from tree-rings. This makes it useful in contexts where timbers are preserved, but dendrochronological dating is impossible. As intertidal and marine timbers are waterlogged, this can favor their preservation and hence allow wiggle-match ¹⁴C dating, which can be of significant help in deriving relatively precise chronologies for a range of coastal structures. As the technique depends on making multiple radiocarbon measurements towards a single date, efficiency in application is the key and hence a number of practical considerations need to be taken into account in advance of conducting a dating program. This paper discusses some of these practical concerns and reviews them in the context of the intertidal crannogs in the Firth of Clyde on the west coast of Scotland.     

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.     

Radiocarbon dating by the accelerator technique

Radiometric dating of archaeological samples by the accelerator mass spectrometry (AMS) technique is well established today. The main advantage of this method compared to the old decay counting procedure is the small sample size (1 mg carbon equivalent weight) needed to carry out a dating. The basic principles as well as the present status of the technique are presented. Experiences from the first year of routine measurements in the Uppsala laboratory are discussed and some examples of the material analysed are given.     

Radiocarbon chronology of Neolithic and Predynastic sites in Upper Egypt and the Delta

Critical evaluation, tree-ring calibration, and statistical analysis of 95 radiocarbon dates from neolithic and predynastic sites in Upper Egypt and the Delta provide the following average age estimates in calendrical years BC. Early Fayum Neolithicca 5200 to 4500 BC Early Merimda Neolithicca 4800 BC Late Merimda Neolithic ?4400 BC Late Fayum Neolithicca 4000 BC Late Badarian? (Hemamieh)ca 4400/4000 BC Early Nagada (Nagada)ca 3750 BC Hierakonpolis (Locs 11 & 29)ca 3550 BC Late Nagada (South Town)ca 3450 BC Other sites or periods are not adequately dated. In addition, further dates are needed to bolster thistentative framework.     

Radiocarbon method in monitoring of fossil fuel emission

The traditional radiocarbon method widely used in archaeology and geology for chronological purposes can also be used in environmental studies. Combustion of fossil fuels like coal, natural gas, petroleum, etc., in industrial and/or heavily urbanized areas, has increased the concentration of carbon dioxide in the atmosphere. The addition of fossil carbon caused changes of carbon isotopic composition, in particular, a definite decrease of ¹⁴C concentration in atmospheric CO₂ and other carbon reservoirs (ocean and terrestrial biosphere), known as the Suess effect. Tree rings, leaves, as well as other annual growing plants reflected the changes of radiocarbon concentration in the atmosphere due to processes of photosynthesis and assimilation of carbon from the air. By measuring radiocarbon concentration directly in atmospheric CO₂ samples and/or biospheric material growing in industrial and/or highly urbanized areas where high emission of dead carbon is expected, it is possible to estimate the total emission of dead CO₂. Based on equations of mass balance for CO₂ concentration, stable isotopic composition of carbon and radiocarbon concentration it is possible to calculate CO₂ con-centration associated with fossil fuel emission into the atmosphere. The procedure use differences between the radiocarbon concentration and stable isotope composition of carbon observed in clean areas and industrial or/and highly urbanized areas.     

Sapwood estimates in the interpretation of tree-ring dates

Many timber finds lack some or all of the outer, sapwood rings formed in the years just before felling. In order to estimate felling date once the outermost remaining ring has been dated, it is necessary to estimate the number of sapwood rings originally present. Methods doing this for oak are reviewed in the light of an intensive study of living trees at one site and an extensive study of 175 samples from living trees in North Wales and northwest England. Some methods reported in the literature are found to be invalid. A method reported by Hollstein (1965) is most reliable, with modifications for known variations in sapwood number with position in the tree. At present the best available estimate is that a value of 30 sapwood rings be used (95% confidence limits: 19–50).     

A Bayesian Radiocarbon Chronology of the Early Neolithic of Yorkshire and Humberside

The Mesolithic-Neolithic transition is one of the mostly hotly (and vociferously) debated periods of British prehistory. Chronology has been key to this discussion. Informal ‘visual’ interpretations of radiocarbon data used both to argue for a rapid uptake of Neolithic practices by indigenous Mesolithic populations, and for the introduction by Continental settlers and then the rapid acculturation by local populations. This paper offers new evidence for the timing of the beginning of the Neolithic in Yorkshire and Humberside, an area with a range of monuments that have been a focus of research into early Neolithic communities. From this new synthesis it is possible to suggest implications for our understanding of ‘neolithization’, but also as to provide the basis for critical future research themes.     

Radiocarbon Dates from the Loughcrew Cairn h Bone Slips

A total of 150 intricately carved bone slips were uncovered at the Loughcrew H passage tomb in Co. Meath, Ireland, during excavations between 1865 and 1943. Studies of the carvings identified La Tène motifs suggesting that the slips may have been Middle to Late Iron Age in date. Joseph Raftery even went so far as to argue that the megalithic tomb itself was an Iron Age construction. His theory has since been debunked, but absolute dates have not been forthcoming for either these finds or the tomb. The following Middle Iron Age results presented here are slightly earlier than the dates that had hitherto been anticipated and they help to shed light on the subsequent interactions with this tomb.     

Radiocarbon Dating and the George C. Davis Site,Texas

Abstract

Seventy-nine radiocarbon samples were assayed from the George C. Davis Site, a prehistoric Caddoan settlement in the central portion of east Texas. Statistical analysis of the dates convincingly establishes the age of the site as extending from about 780 A.C. to 1260 A.C. and enables us to place the cultural remains into three temporal periods. These dates also provide specific and useful examples for improving the application of radiocarbon dating to archaeological problems.     

Radiocarbon dating: Some practical considerations for the archaeologist

The article is divided into four main sections in each of which a key aspect of radio-carbon dating is discussed with emphasis on the practical implications for users of dates. The four topics which the article attempts to deal with are, in turn, (i) the effect on the radiocarbon timescale of the variations in atmospheric ¹⁴C now known to have occurred in the past and the role of other absorlute dating methods in investigating these, (ii) laboratory measurement of ¹⁴C, (iii) selection of optimum samples for dating and (iv) some of the limitations of the final dates. The theme is essentially that the technical difficulties of radiocarbon measurement in the laboratory have been overcome to the extent that the physical measurements can now be made with high precision, that is to within ±1% or better, as a routine. Thus, it is more important than ever (a) that only reliable samples having very firm associations should be dated and (b) that pretreatment of such samples by the dating laboratory to remove any age contaminants should be completely effective. However, in addition to the recognized statistical limitations, the absolute accuracy of radio-carbon dating is limited by the past ¹⁴C variations. Coupled with the requirements of proper association and pretreatment of samples is the long-term need to establish an overall correlation between radiocarbon and calendar years. At present this is still a matter for final agreement by the laboratories concerned. Meanwhile, when all possible steps have been taken to ensure the reliability of the date messurements, these can strictly only be compared with one another in terms of radiocarbon years bp. In practice this is often too restrictive but any attempts at calibration must be regarded as approximations for the time being. In this article the lower and upper case notation advocated in Antiquity46, 265, for radiocarbon and calendar years respectively has been followed.