• Reanalysis of the Chronological Discrepancies Obtained by the Old and Middle Kingdom Monuments Project

      Dee, M. W.; Bronk Ramsey, C.; Shortland, A. J.; Higham, T. F. G.; Rowland, J. M. (Department of Geosciences, The University of Arizona, 2009-01-01)
      The most extensive chronometric study ever undertaken on Egyptian Dynastic sites was published in Radiocarbon by Bonani et al. (2001). It comprised 269 radiocarbon measurements on monuments ranging from the 1st-12th dynasties. However, many of the calibrated dates obtained were significantly offset from historical estimates. The greatest discrepancies occurred in the 4th Dynasty where, paradoxically, the dating program had been most rigorous. For this period, 158 measurements were made at 12 sites, with the majority of the dates being 200-300 yr older than expected. The 4th Dynasty results were especially significant as they included some of the most important monuments in Egypt. In this paper, the raw data from that study have been reanalyzed using the OxCal calibration program, making particular use of its new outlier detection functionality. This Bayesian approach has resulted in a new series of calibrations that show much closer agreement with conventional chronological records.
    • Radiocarbon Reveals the Age of Two Precious Tombs in the Etruscan Site of Populonia-Baratti (Tuscany)

      Scirè Calabrisotto, C.; Fedi, M. E.; Taccetti, F.; Benvenuti, M.; Chiarantini, L.; Quaglia, L. (Department of Geosciences, The University of Arizona, 2009-01-01)
      The archaeological site of Populonia-Baratti, in the southern part of Tuscany (Italy), was one of the most important centers in ancient Etruria, as seen in the evidence of metallurgical activities carried out at that time. During recent archaeological excavations (2005) in the ancient industrial area of Populonia, along the Baratti beach, 2 interesting tombs were found. The 2 graves were unusually located in an area dedicated to metallurgical activity and showed a particular structure of the burial chambers and an extreme richness in the grave goods. The unique character of the 2 tombs prompted many questions: who were these 2 individuals (a woman wearing many jewels and a tall, vigorous man) and when did they die? In order to obtain useful information about the chronology of the 2 tombs, accelerator mass spectrometry (AMS) radiocarbon analyses were performed on samples taken from the ribs of the 2 skeletons. Measured 14C ages were converted to calibrated ages using additional information derived from stable isotope ratios measured in the extracted collagen. Actually, the 13C data provided useful hints about the diet of the 2 individuals, thus allowing us to estimate the percentage of marine food consumed (about 30%) and exploit a combined marine-terrestrial calibration curve. As a result, the age of the 2 individuals can be dated to the 2nd century AD, during Roman times, which is in good agreement with the information obtained from archaeological, anthropological, and stylistic studies of the 2 tombs.
    • A Multiscalar Approach to Modeling the End of the Neolithic on the Great Hungarian Plain Using Calibrated Radiocarbon Dates

      Yerkes, Richard W.; Gyucha, Attila; Parkinson, William (Department of Geosciences, The University of Arizona, 2009-01-01)
      This article presents the results of a multiscalar analysis of 168 radiocarbon dates from Neolithic and Copper Age sites on the Great Hungarian Plain. We examined chronological patterns at different geographic scales to explore socioeconomic changes that occurred during the transition from the Neolithic to the Copper Age. The beginning and end of the Late Neolithic (5000-4500 cal BC) and Early Copper Age (4500-4000 cal BC) were modeled with 14C dates calibrated with the CALIB 5.01 program and IntCal04 calibration curve. Our attempts to identify chronological subphases within these 500-yr-long periods were confounded by multiple intercepts in the calibration curve. The analysis indicated that terminal Late Neolithic (4700-4300 cal BC) and "transitional" Proto-Tiszapolgr occupations (4600-4250 cal BC) at tell sites were contemporary with initial Early Copper Age habitations (4450-4250 cal BC). Calibrated dates from small Early Copper Age settlements at Vsztő-Bikeri and Krsladny-Bikeri document changes in community and household organization that took place over several decades during the transition to the Copper Age. Bayesian analysis indicated that the small fortified sites were occupied contiguously in phases of 30-50 yr. The younger Krsladny-Bikeri site was established before the older Vsztő-Bikeri site was abandoned. When large nucleated Late Neolithic communities dispersed and established small Early Copper Age settlements, the pattern of vertical accretion that had created the Late Neolithic tells gave way to a pattern of horizontal settlement accretion at the smaller settlements.
    • A New Robust Statistical Model for Radiocarbon Data

      Christen, J. Andrés; Pérez E., Sergio (Department of Geosciences, The University of Arizona, 2009-01-01)
      The general method currently used to analyze radiocarbon data (y) is conditional on the standard deviation (), reported by 14C laboratories, which reflects the uncertainty in the dating process. This uncertainty is measured through a series of empirical as well as theoretical considerations about the dating process, chemical preprocessing, etc. Nevertheless, is assumed as known in the statistical model for 14C data used since the dawn of the discipline. This paper proposes a method for the analysis of 14C data where the associated variance is taken as the product of an unknown constant with the sum of the variance reported by the laboratory 2 and the variance of the calibration curve 2() (that is, an unknown error multiplier). Using this approach, assuming that the 14C determination y arises from a Normal population and that, a priori, has an inverse gamma distribution InvGa(a, b), the resulting dating model is a t distribution with 2a degrees of freedom. The introduction of parameters a and b allows a robust analysis in the presence of atypical data and at the same time incorporates the uncertainty associated with the intra- and interlaboratory error assessment processes. Comparisons with the common Normal model show that the proposed t model produces smoother posterior distributions and seem to be far more robust to atypical data, presenting a simpler alternative to the standard 14C outlier analysis. Moreover, this new model might be a step forward in understanding and explaining the otherwise elusive scatter in 14C data seen in interlaboratory studies.
    • A Protocol for Radiocarbon Dating Tropical Subfossil Cave Guano

      Wurster, Christopher M.; Bird, Michael I.; Bull, Ian; Bryant, Charlotte; Ascough, Philippa (Department of Geosciences, The University of Arizona, 2009-01-01)
      We present accelerator mass spectrometry (AMS) radiocarbon dates on several organic fractions isolated from tropical guano deposits recovered from insular Southeast Asia. Differences were observed between 14C measurements made on bulk guano as well as bulk lipids, the saturated hydrocarbon fraction, solvent-extracted guano, and insect cuticles extracted from the same bulk sample. We infer that 14C dates from the bulk lipid fraction and saturated hydrocarbon fractions can be variably contaminated by exogenous carbon. In contrast, 14C measurements on solvent-extracted guano and isolated insect cuticles appear to yield the most robust age determinations.
    • Table of Contents

      Department of Geosciences, The University of Arizona, 2009-01-01
    • The Long-Term Tupiguarani Occupation in Southeastern Brazil

      Macario, K. D.; Buarque, A.; Scheel-Ybert, R.; Anjos, R. M.; Gomes, P. R. S.; Beauclair, M.; Hatté, C. (Department of Geosciences, The University of Arizona, 2009-01-01)
      We discuss some aspects of the chronology of the Tupiguarani occupation in the southeastern Brazilian coast based on the analyses of 3 charcoal samples from the Morro Grande archaeological site (Rio de Janeiro state). 14C beta spectroscopy and accelerator mass spectrometry (AMS) techniques were used to determine ages of 2920 70 BP, 2600 160 BP, and 510 160 BP. The occurrence of these ancient dates in southeastern Brazil has important implications for understanding the origin and dispersion of Tupian populations from Amazonia, supporting recent hypotheses that their expansion must have begun well before 2000 BP. On the other hand, the most recent date is a strong indication of a possible reoccupation of the site by the same cultural group around the time. These results show that the Tupiguarani occupation began at least about 3000 yr ago and lasted until its collapse with the European invasion in the 16th century.
    • Direct Analysis of Automotive Fuels for Bioethanol Content Using Radiocarbon Analysis

      Norton, Glenn A. (Department of Geosciences, The University of Arizona, 2009-01-01)
      Exploratory work was performed to investigate the feasibility of using a simplified radiometric analytical approach for determining the bioethanol content of US automotive fuels. The method involves mixing fuel samples directly with a suitable fluor. Sample preparation is extremely rapid since all conventional sample preparation steps are essentially eliminated. Results are based on the background-corrected DPM values obtained when using 10 mL of sample mixed with 10 mL of Permafluor E+. Results are also reported in terms of conventional pMC for some of the samples. Bioethanol from a dry-mill ethanol plant served as the analytical reference sample that represented a 100% bioethanol content. Using current-day bioethanol as a reference sample eliminates the need to correct for "bomb carbon." For 1:1 mixtures of sample and fluor, the background-corrected DPM showed a linear relationship with the bioethanol concentration, indicating that the quench correction approach was effective for the variable-quench samples. Based on the analysis of E0 (pure gasoline), E10, and "E85" from local gas stations, it appears that the method has good potential for determining the bioethanol content in commercial ethanol/gasoline blends. However, a variety of potential sources of error still require investigation in order to refine the method.
    • Editorial Board

      Department of Geosciences, The University of Arizona, 2009-01-01
    • Variations in 14C Reservoir Ages of Black Sea Waters and Sedimentary Organic Carbon during Anoxic Periods: Influence of Photosynthetic Versus Chemoautotrophic Production

      Fontugne, Michel; Guichard, François; Bentaleb, Ilham; Strechie, Claudia; Lericolais, Gilles (Department of Geosciences, The University of Arizona, 2009-01-01)
      Radiocarbon activity of dissolved inorganic carbon has been measured in the northwestern Black Sea. Both continental shelf and open-sea profiles show that surface waters are in equilibrium with the atmosphere. The observed distribution of 14C activity shows a weak contribution of the deep 14C-depleted CO2 to the photic zone. Such a distribution of 14C within the water column is unable to explain the aging of sedimentary organic matter and reservoir ages greater than 500 yr. A contribution of production by chemoautotrophic bacteria feeding on 14C-depleted methane at the boundary of the oxic and anoxic zones is a realistic hypothesis. Also, a contribution to sedimentary organic carbon estimated at 15% of the photosynthetic primary production could explain 14C reservoir ages greater than 1300 yr.
    • Major Patterns in the Neolithic Chronology of East Asia: Issues of the Origin of Pottery, Agriculture, and Civilization

      Kuzmin, Yaroslav V.; Jull, A. J. Timothy; Burr, G. S. (Department of Geosciences, The University of Arizona, 2009-01-01)
      General chronological frameworks created recently for the Neolithic complexes of China, Japan, Korea, and far eastern Russia allow us to reveal temporal patterns of Neolithization, origin of food production, and the emergence of civilizations. Pottery originated in East Asia, most probably independently in different parts of it, in the terminal Pleistocene, about 14,800-13,300 BP (uncalibrated), and this marks the beginning of the Neolithic. Agriculture in the eastern part of Asia emerged only in the Holocene. The earliest trace of millet cultivation in north China can now be placed at ~9200 BP, and rice domestication in south China is dated to ~8000 BP. Pottery in East Asia definitely preceded agriculture. The term "civilization," which implies the presence of a state level of social organization and written language, has been misused by scholars who assert the existence of a very early "Yangtze River civilization" at about 6400-4200 cal BP. The earliest reliable evidence of writing in China is dated only to about 3900-3000 cal BP, and no "civilization" existed in East Asia prior to this time.
    • Letter from the Editor

      Jull, A. J. T. (Department of Geosciences, The University of Arizona, 2009-01-01)
    • Late Holocene 14C Marine Reservoir Corrections for Hawai'i Derived from U-Series Dated Archaeological Coral

      Weisler, Marshall I.; Hua, Quan; Zhao, Jian-xin (Department of Geosciences, The University of Arizona, 2009-01-01)
      The first application of U-series dating and accelerator mass spectrometry (AMS) assay of Polynesian archaeological Pocillopora spp. branch corals for deriving a precise local marine reservoir correction (Delta-R) is described. Known-age corals were selected that spanned the entire culture-historical sequence for the Hawaiian Islands, thus eliminating the problem of not having known-age dated samples that cover the period of direct relevance to prehistorians; in this case, about AD 700-1800. Dating coral samples from windward and leeward coastlines of Moloka'i Island, with different offshore conditions such as upwelling, currents, wind patterns, coastal topography, and straight or embayed shorelines, provides insights into possible variations of local conditions on the same island--something that has never been attempted. In this regard, there was no spatial variability in Delta-R during the 17th century. We report a weighted average Delta-R value for Moloka'i Island of 52 +/- 25 yr using 12 pair-dated dedicatory branch corals from religious archaeological sites and demonstrate that there is no significant temporal variability in R between about AD 700 to 1800. In combination with 4 selected previously published R values based on pre-bomb known-age marine shells, a revised Delta-R of 66 +/- 54 yr is established for the Hawaiian Islands. However, future research should examine the archipelago-wide spatial variability in Delta-R with the analysis of additional dated archaeological coral samples.
    • Implications of Radiocarbon Dates from Potter Creek Cave, Shasta County, California, USA

      Feranec, Robert S. (Department of Geosciences, The University of Arizona, 2009-01-01)
      New dates obtained from the bone collagen of mammals from the deposits in Potter Creek Cave, Shasta County, California, USA, show that these fossils were emplaced over the last 30,000 yr. The dates support the assignment of the fauna in the cave to the late Pleistocene and are contemporaneous to the dates obtained from the fauna of Samwel Cave located 5 km to the north. These new dates do not support previous radiocarbon dates suggesting a Holocene extinction of the extinct bovid Euceratherium collinum, and demonstrate that this and other megafauna were not present in the vicinity after the terminal Pleistocene.
    • The Beginning of the Early Bronze Age in the North Jordan Valley: New 14C Determinations from Pella in Jordan

      Bourke, Stephen; Zoppi, Ugo; Meadows, John; Hua, Quan; Gibbins, Samantha (Department of Geosciences, The University of Arizona, 2009-01-01)
      This article reports on 10 new accelerator mass spectrometry (AMS) radiocarbon dates from early phases of the Early Bronze Age at the long-lived settlement of Pella (modern Tabaqat Fahl) in the north Jordan Valley. The new AMS dates fall between 3400 and 2800 cal BC, and support a recent suggestion that all Chalcolithic period occupation had ceased by 3800/3700 cal BC at the latest (Bourke et al. 2004b). Other recently published Early Bronze Age 14C data strongly supports this revisionist scenario, suggesting that the earliest phase of the Early Bronze Age (EBA I) occupied much of the 4th millennium cal BC (3800/3700 to 3100/3000 cal BC). As this EB I period in the Jordan Valley is generally viewed as the key precursor phase in the development of urbanism (Joffe 1993), this revisionist chronology has potentially radical significance for understanding both the nature and speed of the move from village settlement towards a complex urban lifeway.
    • The Effects of Possible Contamination on the Radiocarbon Dating of the Dead Sea Scrolls II: Empirical Methods to Remove Castor Oil and Suggestions for Redating

      Lund Rasmussen, Kaare; van der Plicht, Johannes; Doudna, Gregory; Nielsen, Frederik; Højrup, Peter; Halfdan Stenby, Erling; Pedersen, Carl Th. (Department of Geosciences, The University of Arizona, 2009-01-01)
      While kept at the Rockefeller Museum in East Jerusalem, many Dead Sea Scroll fragments were exposed to castor oil by the original team of editors in the course of cleaning the parchments. Castor oil must be regarded as a serious contaminant in relation to radiocarbon dating. If modern castor oil is present and is not removed prior to dating, the 14C dates will be skewed artificially towards modern values. In Rasmussen et al. (2001), it was shown that the standard AAA pretreatment procedure used in the 2 previous studies dating Dead Sea Scroll samples (Bonani et al. 1992; Jull et al. 1995) is not capable of removing castor oil from parchment samples. In the present work, we show that it is unlikely that castor oil reacts with the amino acids of the parchment proteins, a finding which leaves open the possibility of devising a cleaning method that can effectively remove castor oil. We then present 3 different pretreatment protocols designed to effectively remove castor oil from parchment samples. These involve 3 different cleaning techniques: extraction with supercritical CO2, ultrasound cleaning, and Soxhlet extraction--each with their own advantages and disadvantages. Our data show that the protocol involving Soxhlet extraction is the best suited for the purpose of decontaminating the Dead Sea Scrolls, and we recommend that this protocol be used in further attempts to 14C date the Dead Sea Scrolls. If such an attempt is decided on by the proper authorities, we propose a list of Scroll texts, which we suggest be redated in order to validate the 14C dates done earlier by Bonani et al. (1992) and Jull et al. (1995).
    • Pre-Bomb Surface Water Radiocarbon of the Gulf of Mexico and Caribbean as Recorded in Hermatypic Corals

      Wagner, Amy J.; Guilderson, Thomas P.; Slowey, Niall C.; Cole, Julia E. (Department of Geosciences, The University of Arizona, 2009-01-01)
      Radiocarbon measurements of hermatypic corals from 4 sites in the Gulf of Mexico (GOM) and Caribbean Sea were made to estimate the marine 14C reservoir age (R) and the marine regional correction (R) for this region. Coral skeletal material from the Flower Garden Banks (northern GOM continental shelf), Veracruz, Mexico, and 2 reefs from the Cariaco Basin, Venezuela, were analyzed. Annual and subannual samples from 1945-1955 were milled and 14C composition was determined. In the Gulf of Mexico, average coral 14C is -52.6 0.7 and average 14C for the Cariaco Basin corals is -53.4 0.8. Average values for the marine reservoir age and R are computed with this data and compared with results derived from previous measurements made in the same regions. These values are important in calibrating the 14C ages of carbonate samples from the area.
    • Possible Evidence of Pre-Columbian Transoceanic Voyages Based on Conventional LSC and AMS 14C Dating of Associated Charcoal and a Carbonized Seed of Custard Apple (Annona squamosa L.)

      Kumar Pokharia, Anil; Sekar, B.; Pal, Jagannath; Srivastava, Alka (Department of Geosciences, The University of Arizona, 2009-01-01)
      An attempt was made to trace the antiquity of custard apple in India on the basis of accelerator mass spectrometry (AMS) and liquid scintillation counting (LSC) radiocarbon dates. Recently, seed remains of custard apple (Annona squamosa L.) in association with wood charcoals were encountered from the Neolithic archaeological site of Tokwa at the confluence of the Belan and Adwa rivers, Mirzapur District, in the Vidhyan Plateau region of north-central India. The wood charcoal sample was dated at the 14C laboratory of the Birbal Sahni Institute of Palaeobotany (BSIP), Lucknow, by conventional LSC 14C dating. The sample dated to 1740 cal BC (BS-2054). A seed sample of custard apple was dated by AMS at the Institute of Physics 14C laboratory, Bhubaneswar, India (3MV tandem Pelletron accelerator). Interestingly, the AMS date was given as 1520 cal BC (IOPAMS-10), showing a reasonable agreement with the LSC date carried out at BSIP. On botanical grounds, the custard apple is native to South America and the West Indies and was supposed to have been introduced in India by the Portuguese in the 16th century. The present 14C dates of the samples pushes back the antiquity of custard apple on Indian soil to the 2nd millennium BC, favoring a group of specialists proposing diverse arguments for Asian-American transoceanic contacts before the discovery of America by Columbus in AD 1492.
    • Dealing with Outliers and Offsets in Radiocarbon Dating

      Bronk Ramsey, Christopher (Department of Geosciences, The University of Arizona, 2009-01-01)
      The wide availability of precise radiocarbon dates has allowed researchers in a number of disciplines to address chronological questions at a resolution which was not possible 10 or 20 years ago. The use of Bayesian statistics for the analysis of groups of dates is becoming a common way to integrate all of the 14C evidence together. However, the models most often used make a number of assumptions that may not always be appropriate. In particular, there is an assumption that all of the 14C measurements are correct in their context and that the original 14C concentration of the sample is properly represented by the calibration curve. In practice, in any analysis of dates some are usually rejected as obvious outliers. However, there are Bayesian statistical methods which can be used to perform this rejection in a more objective way (Christen 1994b), but these are not often used. This paper discusses the underlying statistics and application of these methods, and extensions of them, as they are implemented in OxCal v 4.1. New methods are presented for the treatment of outliers, where the problems lie principally with the context rather than the 14C measurement. There is also a full treatment of outlier analysis for samples that are all of the same age, which takes account of the uncertainty in the calibration curve. All of these Bayesian approaches can be used either for outlier detection and rejection or in a model averaging approach where dates most likely to be outliers are downweighted. Another important subject is the consistent treatment of correlated uncertainties between a set of measurements and the calibration curve. This has already been discussed by Jones and Nicholls (2001) in the case of marine reservoir offsets. In this paper, the use of a similar approach for other kinds of correlated offset (such as overall measurement bias or regional offsets in the calibration curve) is discussed and the implementation of these methods in OxCal v 4.0 is presented.
    • Foraminiferous Limestone in 14C Dating of Mortar

      Goslar, Tomasz; Nawrocka, Danuta; Czernik, Justyna (Department of Geosciences, The University of Arizona, 2009-01-01)
      Mortar as a mixture of binder and aggregate can be reliably dated with radiocarbon if the applied preparation method allows one to eliminate unburnt carbonate fragments, bearing 14C-depleted carbon and causing overestimation of 14C age. To avoid these problems, separation of specific grain-size fractions of mortar and 14C analysis of the CO2 portions collected in different time intervals of the acid-leaching reaction is usually helpful. In the present paper, we demonstrate that the rate of the leaching reaction of mortars with dense carbonate aggregate differs from that of mortars with crumbled limestone and scattered shells (e.g. of foraminifera). Verification of the obtained 14C dates against historical sources shows that for mortars rich in foraminiferous limestone, a reaction rate-based chemical elimination of "dead carbon" may appear impossible.