• C. E. Buck, W. G. Cavanagh and C. D. Litton. Bayesian Approach to Interpreting Archaeological Data

      Scott, Marian (Department of Geosciences, The University of Arizona, 1997-01-01)
      Reviewed by Marian Scott, Department of Statistics, University of Glasgow
    • Cairo Natural Radiocarbon Measurements I

      Nakhla, Shawki M.; Mohammed, Ferial M. (American Journal of Science, 1974-01-01)
    • Calculating Sediment Compaction for Radiocarbon Dating of Intertidal Sediments

      Bird, M. I.; Fifield, L. K.; Chua, S.; Goh, B. (Department of Geosciences, The University of Arizona, 2004-01-01)
      This study estimates the maximum and minimum degrees of autocompaction for radiocarbon-dated Holocene mangrove sediments in Singapore, in order to correct apparent sediment accretion rates for the effects of sediment compression due to autocompaction. Relationships developed for a suite of modern (surface) sediment samples between bulk density, particle-size distribution, and organic matter content were used to estimate the initial (uncompacted) bulk density of buried and variably compressed Holocene sediments, based on the grain-size distribution and organic matter content of the sediment. The difference between measured (compacted) and initial (uncompacted) bulk density of each buried sediment interval can be interpreted as the amount of length shortening experienced by each interval since burial. This allows the elevation of samples selected for 14C dating to be corrected for the effects of autocompaction of the underlying sediment sequence, so that accurate estimates of vertical sediment accretion rates can be calculated. The 3 Holocene mangrove sequences analyzed and dated for this study ranged in age from 2000 to 8500 cal BP. The effects of autocompaction are significant, even in comparatively thin sequences, with subsidence of up to 56 cm calculated for carbon-dated samples presently 2 m above incompressible basement. The vertical sediment accretion rates for these mangrove sequences ranged from 0.99 to 6.84 mm/yr and carbon sequestration rates ranged from 0.9 to 1.7 t/ha/yr, all within the range observed for comparable Holocene and modern mangrove sediments elsewhere.
    • Calculation of Past Dead Carbon Proportion and Variability by the Comparison of AMS 14C and TIMS U/Th Ages on Two Holocene Stalagmites

      Genty, Dominique; Massault, Marc; Gilmour, Mabs; Baker, Andy; Verheyden, Sophie; Keppens, Eddy (Department of Geosciences, The University of Arizona, 1999-01-01)
      Twenty-two radiocarbon activity measurements were made by accelerator mass spectrometry (AMS) on 2 Holocene stalagmites from Belgium (Han-stm lb) and from southwest France (Vil-stm lb). Sixteen thermal ionization mass spectrometric (TIMS) U/Th measurements were performed parallel to AMS analyses. The past dead carbon proportion (dcp) due to limestone dissolution and old soil organic matter (SOM) degradation is calculated with U/Th ages, measured calcite 14C activity and atmospheric 14C activity from the dendrochronological calibration curves. Results show that the dcp is different for the 2 stalagmites: between 10,800 and 4780 yr from present dcp = 17.5% (sigma = 2.4; n = 10) for Han-stm lb and dcp = 9.4% (sigma = 1.6; n = 6) between 3070 and 520 yr for Vil-stmlb. Despite a broad stability of the dcp during the time ranges covered by each sample, a slight dcp increase of about 5.0% is observed in the Han-stmlb sample between 8500 and 5200 yr. This change is synchronous with a calcite delta-13C increase, which could be due to variation in limestone dissolution processes possibly linked with a vegetation change. The dcp and delta-13C of the 2 studied samples are compared with 5 other modern stalagmites from Europe. Results show that several factors intervene, among them: the vegetation type, and the soil saturation leading to variable dissolution process systems (open/closed). The good correlation (R2 = 0.98) between the U/Th ages and the calibrated 14C ages corrected with a constant dcp validates the 14C method. However, the dcp error leads to large 14C age errors (i.e. 250-500 yr for the period studied), which is an obstacle for both a high-resolution chronology and the improvement of the 14C calibration curves, at least for the Holocene.
    • Calendar Age of Lisakovsky Timbers Attributed to Andronovo Community of Bronze Age in Eurasia

      Panyushkina, Irina P.; Mills, Barbara J.; Usmanova, Emma R.; Cheng, Li (Department of Geosciences, The University of Arizona, 2008-01-01)
      We measured radiocarbon ages of 22 decadal replications and 1 bulk group from 5 tree-ring specimens using acid-base-acid pretreatment and accelerator mass spectrometry (AMS). The study has the goal of refining the precision and resolution of a segment of the conventional Bronze Age chronology in the Eurasian steppe attributed to the multicultural community known as Andronovo. The archaeological timbers were gathered from 3 cemeteries at the Lisakovsky cluster of sites in Kazakhstan, where there is a prominent Andronovo occurrence that appears to show evidence of overlapping Alakul and Fedorovo cultures in the southern margin of the Eurasian steppe. The new set of Andronovo calendar dates derived from 14C wiggles and a composite floating tree-ring chronology places the cultural overlap from 1780 to 1660 cal BC. Results indicate older ages of artifacts from the Lisakovsky site than were previously determined by the typological chronology, shifting them from the Late Bronze Age to also include the transition between the Middle and Late Bronze Age. The chronological order of the Lisakovsky cemeteries provides strong evidence of contemporaneity of the Alakul and Fedorovo cultures in the Tobol River Valley for a portion of the 120-yr period of occupation. We discuss an application of the dated Alakul-Fedorovo overlap to the relationship and origin of different groups of the Andronovo community in the Ural region. Our results demonstrate the substantial power that tree rings from Bronze Age timbers provide for developing a precise and highly resolved calendar chronology of prehistoric human occupation in the Eurasian steppe during the 2nd millennium BC.
    • CalibETH: An Interactive Computer Program for the Calibration of Radiocarbon Dates

      Niklaus, Thomas R.; Bonani, Georges; Simonius, Markus; Suter, Martin; Wölfli, Willy (Department of Geosciences, The University of Arizona, 1992-01-01)
      A computer program for convenient calibration of radiocarbon dates has been developed. The program has a simple user interface, which includes pull-down menus, windows and mouse support. All important information, such as calibration curves, probability density function and results, in text form, are displayed on the screen and easily can be rearranged by the user. Two versions of CalibETH, one for an IBM-PC and one for the Macintosh, are available. CalibETH runs under the graphics interface, GEM, from Digital Research, on an IBM PC.
    • Calibrated 14C Ages of Jomon Sites, NE Japan, and Their Significance

      Omoto, K.; Takeishi, K.; Nishida, S.; Fukui, J. (Department of Geosciences, The University of Arizona, 2010-01-01)
      The traditional archaeological chronology in the Japanese Islands during the Jomon period was essentially based on the relative age given to cord-impressed patterns marked on pottery, as well as the shape of the pottery and the thickness of the cultural layers that were excavated. We aimed to correlate the classical archaeological chronology with calibrated radiocarbon dates, to posit a new chronology for the Jomon period in northeastern Japan. We calibrated 80 accelerator mass spectrometry (AMS) 14C dates from NE Japan and reconstructed a chronological timetable for Hokkaido and the Tohoku District. We collected 43 samples from 5 shellmounds and 2 archaeological sites on Hokkaido Island and 4 shellmounds in the Tohoku District in order to determine the calibrated age of their sites. R values used on Hokkaido Island and the Tohoku District were between 282 and -158 yr and between 0 and -40 yr, respectively. The large R value for the eastern part of Hokkaido Island indicates the influence of the Oyashio Current, while an anomalous R value was obtained from northern Hokkaido Island. These figures show larger apparent R values than those from southwest Japan (Nakamura et al. 2007). The calibrated Jomon period in the investigated area was from 2000 to 200 yr younger than the previous chronology. Calibrated 14C ages of the shellmounds investigated ranged between ~6000 and 3000 yr, correlating to the Early Jomon and Final Jomon periods as indicated by the former archaeological chronology of Honshu Island.
    • Calibrated 14C Dates in Central Europe - Same as Elsewhere?

      Freundlich, J. C.; Schmidt, Burghart (American Journal of Science, 1983-01-01)
      14C dating results derived from an absolutely-dated 471-year tree-ring sequence from central European oak show a trend towards somewhat older dates than those for bristlecone pine tree rings of the same age, but similar to those for Egyptian historical samples. Differences visible between these trend lines are not relevant considering the standard errors proposed by Clark (1975).
    • Calibrating New Zealand Radiocarbon Dates of Marine Shells

      McFadgen, B. G.; Manning, M. R. (Department of Geosciences, The University of Arizona, 1990-01-01)
      Radiocarbon activity of 11 modern marine shell samples from the New Zealand region is enhanced compared with the surface layers of the average world ocean. The measured enhancement, Delta-R, is equivalent to -31 +/13 years. On this basis, the Institute of Nuclear Sciences will now use a value of -30 years in reporting calibrated ages for marine shell samples.
    • Calibration 1993

      Department of Geosciences, The University of Arizona, 1993-01-01
    • Calibration 1993

      Department of Geosciences, The University of Arizona, 1994-01-01
    • Calibration 1993

      Department of Geosciences, The University of Arizona, 1994-01-01
    • Calibration 1993

      Department of Geosciences, The University of Arizona, 1995-01-01
    • Calibration Commentary

      Blockley, S. P. E.; Housley, R. A. (Department of Geosciences, The University of Arizona, 2009-01-01)
      Radiocarbon is by far and away the most widely used dating tool in the Late Quaternary. Hundreds of key papers rely on the method to provide absolute and relative chronological information on important topics, including the late evolution of our own species (e.g. Higham et al. 2006a) and the timing and nature of abrupt climatic changes during the last glaciation (Lowe et al. 2001). Calibration of 14C determinations is an essential part of the dating process, and the implications of calibration can lead to significant differences in the interpretation of important processes (Blockley et al. 2006). Any development that enhances the accuracy, precision, or time coverage of the calibration curves is therefore to be welcomed. Since the early 1980s, there has been periodic publication of carefully vetted data in the form of internationally recognized consensus calibration curves that have allowed 14C users to convert their raw 14C determinations into calendar ages (Klein et al. 1982; Stuiver and Reimer 1986, 1993; Stuiver et al. 1998; Reimer et al. 2004). In the beginning, the basis on which this was done was easy to understand, 14C measurements were made on tree rings and the absolute calendar age came from counting annual growth rings. Although not without its complexities, the terrestrial tree-ring approach remains the most certain method and is at the heart of calibration process in the period 0-12.4 cal kyr. However, for periods beyond the limit of the tree-ring sequences the situation was significantly more problematic, and at times, even controversial.
    • Calibration Curve for Short-Lived Samples, 1900-3900 BC

      Vogel, J. C.; van der Plicht, Johannes (Department of Geosciences, The University of Arizona, 1993-01-01)
    • Calibration Introduction

      Scott, E. M.; Reimer, P. J. (Department of Geosciences, The University of Arizona, 2009-01-01)
      There are 2 fundamental assumptions in radiocarbon dating, which were known early in the method development to be approximations, and which lead directly to the need to calibrate 14C dates: 1. The rate of formation of 14C in the upper atmosphere has been constant over the entire applied 14C dating timescale (approximately the last 65,000 yr). 2. The 14C activity of the atmosphere has been in equilibrium with the biosphere and ocean over the applied timescale.
    • Calibration of 14C Histograms: A Comparison of Methods

      Stolk, Ad; Törnqvist, Törbjorn E.; Hekhuis, Kilian V.; Berendsen, Henk A.; van der Plicht, Johannes (Department of Geosciences, The University of Arizona, 1994-01-01)
      The interpretation of 14C histograms is complicated by the non-linearity of the 14C time scale in terms of calendar years, which may result in clustering of 14C ages in certain time intervals unrelated to the (geologic or archaeologic) phenomenon of interest. One can calibrate 14C histograms for such distortions using two basic approaches. The KORHIS method constructs a 14C histogram before calibration is performed by means of a correction factor. We present the CALHIS method based on the Groningen calibration program for individual 14C ages. CALHIS first calibrates single 14C ages and then sums the resulting calibration distributions, thus yielding a calibrated 14C histogram. The individual calibration distributions are normalized to a standard Gaussian distribution before superposition, thus allowing direct comparison among various 14C histograms. Several experiments with test data sets demonstrate that CALHIS produces significantly better results than KORHIS. Although some problems remain (part of the distortions due to 14C variations cannot be eliminated), we show that CALHIS offers good prospects for using 14C histograms, particularly with highly precise and accurate 14C ages.
    • Calibration of Lacustrine Sediment Ages Using the Relationship between 14C Levels in Lake Waters and in the Atmosphere: The Case of Lake Kinneret

      Stiller, Mariana; Kaufman, Aaron; Carmi, Israel; Mintz, Genia (Department of Geosciences, The University of Arizona, 2001-01-01)
      The source of endogenic organic and inorganic carbon in lacustrine sediments is the dissolved inorganic carbon (DIC) in the lake water. The relation between the radiocarbon levels of DIC in Lake Kinneret and of CO2 in the atmosphere has been investigated. The ratio of the former to the latter was found to be 0.814 +/0.013. This ratio is used for calibrating the age of the sediment according to the natural fluctuations in the atmospheric levels of 14C that occurred during the past 10,000 years.
    • Calibration of Mangerud's Boundaries

      Walanus, Adam; Nalepka, Dorota (Department of Geosciences, The University of Arizona, 2010-01-01)
      The "calibration" of arbitrarily defined (in some sense, "conventional") ages, given in conventional radiocarbon years BP, is now becoming necessary because the term "radiocarbon age" is used less often in archaeological and Quaternary practice. The standard calibration procedure is inappropriate here because Mangerud's boundaries are not measurement results. Thus, another approach to the problem is proposed in order to model the natural situation of many, uniformly distributed, dated samples, which should be similarly divided by the original and "calibrated" boundary. However, the result depends on the value of the typical measurement error and is not unequivocal.
    • Calibration of Radiocarbon Ages by Computer

      van der Plicht, Johannes; Mook, W. G. (Department of Geosciences, The University of Arizona, 1989-01-01)
      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 3-sigma 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.