Eva Maria Wild

Direct dating of Early Upper Palaeolithic human remains from Mladec.

The human fossil assemblage from the Mladeč Caves in Moravia (Czech Republic) has been considered to derive from a middle or later phase of the Central European Aurignacian period on the basis of archaeological remains (a few stone artefacts and organic items such as bone points, awls, perforated teeth), despite questions of association between the human fossils and the archaeological materials and concerning the chronological implications of the limited archaeological remains. The morphological variability in the human assemblage, the presence of apparently archaic features in some specimens, and the assumed early date of the remains have made this fossil assemblage pivotal in assessments of modern human emergence within Europe. We present here the first successful direct accelerator mass spectrometry radiocarbon dating of five representative human fossils from the site. We selected sample materials from teeth and from one bone for 14C dating. The four tooth samples yielded uncalibrated ages of ∼31,000 14C years before present, and the bone sample (an ulna) provided an uncertain more-recent age. These data are sufficient to confirm that the Mladeč human assemblage is the oldest cranial, dental and postcranial assemblage of early modern humans in Europe and is therefore central to discussions of modern human emergence in the northwestern Old World and the fate of the Neanderthals.

14C dating with the bomb peak: An application to forensic medicine

Abstract Samples originating from the time period after 1950 can be radiocarbon dated utilising the 14C bomb peak as a calibration curve. The applicability of “radiocarbon dating” of recent organic human material for the determination of the time of death of humans was tested. The radiocarbon results from hair and lipid samples from individuals with known date of death were compared with the results from two individuals with unknown time of death. An estimate of the year of death for the unknowns could be derived by this way. Due to the long turnover time of collagen in human bones it is not possible to use the radiocarbon content of bone collagen for a reliable estimate. In order to study the time dependence of the collagen turnover we tested “soft” chemical methods for the isolation of collagen from the bone matrix. First radiocarbon results of this investigation are presented.

Radiocarbon-based chronology for dynastic Egypt.

Date with the Pharaohs Ancient Egypt dominated the Mediterranean world for several thousand years. However, the absolute chronology of this civilization has been uncertain, even though the sequence of rulers is well documented. Bronk Ramsey et al. (p. 1554; see the Perspective by Bruins) now provide a detailed radiocarbon-based record using more than 200 samples that spans much of this time and reduces uncertainties in some cases to less than 20 years. To avoid artifacts, the authors dated only short-lived plant remains from known contexts (i.e., that were associated with specific reigns). They then used the known reign lengths as a further constraint to obtain a final chronology. The final dates agree most closely with the previous older chronology but force some revisions to the timing of events in the Old Kingdom, the period in the third millennium B.C.E. when Egypt attained its first continuous peak of civilization. Many radiocarbon dates from short-lived plant remains provide a long and accurate chronology for ancient Egypt. The historical chronologies for dynastic Egypt are based on reign lengths inferred from written and archaeological evidence. These floating chronologies are linked to the absolute calendar by a few ancient astronomical observations, which remain a source of debate. We used 211 radiocarbon measurements made on samples from short-lived plants, together with a Bayesian model incorporating historical information on reign lengths, to produce a chronology for dynastic Egypt. A small offset (19 radiocarbon years older) in radiocarbon levels in the Nile Valley is probably a growing-season effect. Our radiocarbon data indicate that the New Kingdom started between 1570 and 1544 B.C.E., and the reign of Djoser in the Old Kingdom started between 2691 and 2625 B.C.E.; both cases are earlier than some previous historical estimates.

14C Dating of the Upper Paleolithic Site at Krems-Hundssteig in Lower Austria

The open-air archaeological site at Krems-Hundssteig is a well-known Upper Paleolithic site located in Lower Austria. The site was discovered in the late 19th/early 20th centuries when a large number of archaeological remains were col- lected during the course of loess quarrying. Although no systematic excavation has ever been performed, Krems-Hundssteig has been described since its discovery as typical of the Aurignacian period in this region based on the numerous archaeolog- ical finds; accordingly, the culture has been named Kremsien by some authors. Surprisingly, the artifacts found in a recent excavation adjacent to this location showed solely Gravettian features, calling into question the original assignment to the Aurignacian. Although the earlier assignment was supported by a radiocarbon date of ~35 kyr BP (Hahn 1977), new accel- erator mass spectrometry (AMS) 14C dates proved that the recently excavated cultural layer originates from the Gravettian period. Older paleosols were also detected by sondage drillings at some depth below it. The new results indicate that a large Aurignacian level and a substantial complex of Gravettian layers are present in this area. Therefore, it must be assumed that more than 1 cultural level was affected and destroyed by the historic loess quarrying, and that the assemblage of Krems-Hundssteig artifacts, traditionally ascribed to the Aurignacian, might be interspersed with Gravettian pieces.

Pushing the precision limit of 14C AMS

High precision for radiocarbon cannot be reached without profound insight into the various sources of uncertainty which only can be obtained from systematic investigations. In this paper, we present a whole series of investigations where in some cases (super 16) O: (super 17) O: (super 18) O served as a substitute for (super 12) C: (super 13) C: (super 14) C. This circumvents the disadvantages of event counting, providing more precise results in a much shorter time. As expected, not a single effect but a combination of many effects of similar importance were found to be limiting the precision. We will discuss the influence of machine tuning and stability, isotope fractionation, beam current, space charge effects, sputter target geometry, and cratering. Refined measurement and data evaluation procedures allow one to overcome several of these limitations. Systematic measurements on FIRI-D wood show that a measurement precision of + or -20 (super 14) C yr (1 sigma ) can be achieved for single-sputter targets.

VERA: A new AMS facility in Vienna

Abstract The basic features of VERA, a new AMS facility based on a 3-MV Pelletron tandem accelerator installed at the University of Vienna, are presented.

First performance tests of VERA

VERA is a new 3-MV Pelletron tandem AMS facility in Vienna, which was installed during the last months of 1995. This report will discuss the performance characteristics of the facility established during the test operating phase and present first measurements of 14C standards.

14C DATING OF THE UPPER PALEOLITHIC SITE AT KREMS-WACHTBERG, AUSTRIA

In the course of new excavations at the Upper Paleolithic site at Krems-Wachtberg in the loess region near Krems, Lower Austria, a double burial of newborns was discovered in 2005. One year later, a single grave of an infant was excavated nearby. Both graves are associated with the well-preserved living floor of an Upper Paleolithic hunter-gatherer camp with distinct archaeological features and a rich Gravettian find assemblage. Several charcoal samples from different stratigraphic positions were 14C dated with the accelerator mass spectrometry (AMS) method at VERA. The 14C ages confirm the archaeological assessment of the site to the Gravettian time period. According to the uncalibrated 14C ages, the formation time of the living floor is ~27.0 14C kyr BP. 14C data of ~28.6 14C kyr BP determined for an archaeological horizon below the living floor indicate that the location may have been used earlier by people in the Middle Upper Paleolithic.

Systematic Investigations of 14C Measurements at the Vienna Environmental Research Accelerator

A newly operating accelerator mass spectrometry (AMS) facility such as VERA has to go through an extensive testing phase in order to establish optimal conditions for (super 14) C measurements, especially in the field of archaeological samples where an overall precision of 0.5% is desirable. We discuss the results of our measurements at the milligram carbon level as they relate to long-term stability, reproducibility, precision and isotope fractionation.

RADIOCARBON DETERMINATION OF PARTICULATE ORGANIC CARBON IN NON-TEMPERATED, ALPINE GLACIER ICE

Dating ice samples from glaciers via radiocarbon is a challenge that requires systematic investigations. This work describes an approach for extraction and accelerator mass spectrometry (AMS) 14C analysis of the particulate organic carbon (POC) fraction in glacier ice samples. Measurements were performed at VERA (Vienna Environmental Research Accelerator) on ice samples obtained mainly from the non-temperated ablation zone of the Grenzgletscher (Grenz Glacier) system (Monte Rosa Massif, Swiss Alps). The samples were obtained from 2 sampling sites situated roughly on a common flow line. The sample masses used were between 0.3 and 1.4 kg of ice, yielding between 18 and 307 g of carbon as POC. The carbon contamination introduced during sample processing varied between 5.4 and 33 g C and originated mainly from the quartz filters and the rinsing liquids used in processing. Minimum sample sizes for successful graphitization of CO2 in our laboratory could be reduced to <10 g carbon, with a background in the graphitization process of ~0.5 g of 40-pMC carbon. Evaluation of the whole procedure via 11 Grenzgletscher samples revealed a surprisingly large scatter of pMC values. We obtain a mean calibrated age of 2100 BC to AD 900 (95.4% confidence level), which is not significantly different for the 2 sampling sites. Discussions of these results suggest that single 14C dates of glacial POC are presently of limited significance. Future improvements with respect to analytical precision and sample characterization are proposed in order to fully explore the POC dating potential.