The 5th International Radiocarbon and Archaeology Symposium was held at the ETH Zurich between March 26th and 28th, 2008. A total of 164 participants (including 47 students) from 28 countries attended the symposium. We had presentations of 13 invited speakers who opened 6 thematic/topic sessions that included 31 oral presentations and 49 posters.

A slice of pine from the period covered by single-year calibration data (Stuiver 1993) was selected to serve as part of the quality assurance procedures of the English Heritage radiocarbon dating program, following successful wiggle-matching of 14C measurements from structural 15th century English oak timbers (Hamilton et al. 2007). The timber selected was a roofing element from a house on Jermyn Street, central London, demonstrated by dendrochronology to have been felled in AD 1670. Eighteen single-ring samples were dated by the 14C laboratories at Groningen, Oxford, and SUERC: each laboratory was sent a random selection of 6 samples. This approach was intended to mimic the mix of samples and relative ages incorporated into Bayesian chronological models during routine project research. This paper presents the results of this study.

Deposits from the Minoan Santorini (Thera) eruption in the eastern Mediterranean region constitute the most important regional stratigraphic marker in the chronological perplexity of the 2nd millennium BCE. Extensive tsunami deposits were discovered in Crete at the Minoan archaeological site of Palaikastro, containing reworked volcanic Santorini ash. Hence, airborne deposition of volcanic ash, probably during the 1st (Plinian) eruption phase, preceded the tsunami, which was apparently generated during the 3rd or 4th phase of the eruption, based on evidence from Thera. Average radiocarbon dates (uncalibrated) of animal bones in the Palaikastro tsunami deposits along the coast (3350 ± 25 BP) and at the inland archaeological site (3352 ± 23 BP) are astoundingly similar to the average 14C date for the Minoan Santorini eruption at Akrotiri on Thera (3350 ± 10 BP). The wiggle-matched 14C date of the eruption in calendar years is 1627–1600 cal BCE. Late Minoan IA pottery is the youngest element in the Palaikastro tsunami deposits, fitting with the LM IA archaeological date for the Santorini eruption, conventionally linked at ~1500 BCE with Dynasty XVIII of the historical Egyptian chronology. The reasons for the discrepancy of 100–150 yr between 14C dating and Egyptian chronology for part of the 2nd millennium BCE are unknown. 14C dates from Tell el-Dabca in the eastern Nile Delta show that the 14C age of the Santorini eruption matches with 14C results from 18th Dynasty strata C3 and C2, thereby confirming grosso modo the conventional archaeo-historical correlations between the Aegean and Egypt. We propose that a dual dating system is used in parallel: (1) archaeological material-cultural correlations linked to Egyptian chronology; (2) 14C dating. Mixing of dates from the 2 systems may lead to erroneous archaeological and historical correlations. A “calibration curve” should be established between Egyptian chronology and 14C dating for the 2nd millennium BCE, which may also assist to resolve the cause of the discrepancy.

Twelve monoxylous boats were analyzed from different provinces of northern Italy by radiocarbon and dendrodating. Most of them were dated in the range 6th–12th centuries cal AD. All boats were made from single tree trunks containing ~50 to ~250 tree rings. The results from archaeometric dating in logboats confirm that these kinds of vessels remained practically unchanged for centuries and were in use until recently. The technical features are more strictly related to local traditions than to chronology.

The present research is focused on the dating of the Oglakhty burial ground, the key site of stage I of the Tashtyk culture. Despite the numerous well-preserved burials of that type investigated at the Oglakhty complexes, their chronological position has remained unclear. From the early 20th century until the present, 2 different time periods had been identified for the Tashtyk burials: (1) from the 1st century BC until the 1st century AD and (2) from the 1st until the 2nd century AD. New data obtained in the 1990s suggested a different age for Tashtyk burials, namely the 3rd–4th centuries AD. This considerable shift in chronology needed to be checked with independent data. The chronological position of one of the Oglakhty burials, tomb 4, has been investigated with the use of wiggle-matching, applied to wooden logs used in the construction of tomb 4. The resulting dates for this burial strongly suggest its age as being limited to the 3rd–4th centuries AD, which is corroborated by the archaeological dates of the imported artifacts found in the grave and which is in agreement with the chronological position of the Oglakhty site, as proposed by previous investigations.

Systematic bias of dates can became statistically significant regarding the growing global number of dates connected with the calibration curve plateau. For example, samples of true age in the span 800–700 BC are dated to be roughly 100 younger, on average. The curve of expected bias for a given age is presented. To avoid such a bias, the Bayesian paradigm probably must be modified in some way.

Radiocarbon dating of charcoal in soils is commonly used to reconstruct past environmental processes. Also microcharcoal that is chemically isolated from soil organic matter by high-energy UV photo-oxidation can be dated with 14C accelerator mass spectrometry (AMS). We compared the 14C AMS ages of 13 pairs of hand-picked macrocharcoals and microcharcoal samples separated via the UV oxidation method; both charcoal fractions were taken from the same soil samples (prehistoric pit fillings). We found that in most cases, the microcharcoal fraction yielded older ages than the single macrocharcoal pieces, and that the differences between the ages are not systematic. A reason for these age differences might be that the microcharcoal fraction consists of more stable components than macrocharcoals and thus yields older ages. Dating of microcharcoal would give a mean age of charred organic matter in soil material and the ages of the more stable compounds. Thus, 14C data obtained from the microcharcoal fraction in soils is not comparable to macrocharcoal ages and should not be used to complement existing macrocharcoal data sets.

The area of Chroberz (southern Poland) poses questions of an interdisciplinary character comprising geomorphologic, sedimentation, and archaeological-historical problems. The main aim of this study was to identify the geomorphologic response to changes in the natural environment that took place in the area of the loess plateau (and its close vicinity) as a result of its settlement by man and of climate change. Periods of particularly intense human activity (land-use changes, deforestation, and agriculture) were recorded as changes in the type of sedimentation, i.e. organic sedimentation substituted for mineral one; it was extremely intensive during the Neolithic Age, Iron Age, and Early Middle Ages. The conducted fieldwork research, analysis of available archaeological materials, and radiocarbon dating results show that there is a direct connection between human economic activity in primeval and historic times and between soil erosion and accumulation of colluvial/alluvial fans in the surroundings of the locality of Chroberz. 14C dates documenting the age of colluvial sediment formation show that individual areas of the upland were settled by humans asynchronously. On the basis of a low facial variability, or, occasionally, even homogeneity, of individual colluvia (from soil erosion) and their considerable thickness, it can be concluded that the land was in constant use or that the intervals with no human activity were relatively short. The progressing human impact process is visible both in the form progradation recorded as the changes in 14C ages (e.g. from 1440 ± 100 to 780 ± 80 BP) and in textural (e.g. chemical) features of sediments of which the examined fans are composed.

At Ounjougou, a site complex situated in the Yamé River valley on the Bandiagara Plateau (Dogon country, Mali), multidisciplinary research has revealed a rich archaeological and paleoenvironmental sequence used to reconstruct the history of human-environment interactions, especially during the Late Holocene (3500–300 cal BC). Geomorphological, archaeological, and archaeobotanical data coming from different sites and contexts were combined in order to elaborate a chronocultural and environmental model for this period. Bayesian analysis of 54 14C dates included within the general Late Holocene stratigraphy of Ounjougou provides better accuracy for limits of the main chronological units, as well as for some particularly important events, like the onset of agriculture in the region. The scenario that can be proposed in the current state of research shows an increasing role of anthropogenic fires from the 3rd millennium cal BC onwards, and the appearance of food production during the 2nd millennium cal BC, coupled with a distinctive cultural break. The Late Holocene sequence ends around 300 cal BC with an important sedimentary hiatus that lasts until the end of the 4th century cal AD.

Archaeological excavations performed for many years in Łekno, central Poland, have exposed relicts of wooden fortified settlements, and in its enclosure also basements of stone buildings, consisting of Romanesque rotunda and a Cistercian monastery, including an oratory, church, and abbot's house. Earlier archaeological, structural, and stratigraphical studies have shown that these buildings were constructed in a sequence and represented several phases of development.

In this paper, we present results of radiocarbon dating of stone buildings of the rotunda and the monastery. For 14C dating, we used tiny pieces of charcoal retrieved from calcareous and gypsum mortar binding stone elements from the buildings. These pieces were incorporated in mortar during the firing process, where the fuel used for firing was wood. Most of the obtained 14C dates formed clear groups, confirming that individual buildings were constructed in separate periods. Calibrated 14C dates of these phases agree well with the constraints provided by historical sources, and enable us to set their ages with accuracy better than previously available. In particular, we have learned that the oldest rotunda was built at the boundary of the 10/11th centuries, and the church and the abbot's house, before AD 1250. However, some samples gave much too old 14C ages, clearly reflecting the use of old wood for firing. These problems were revealed only for samples from the rotunda and for the gypsum stone ornamental details.

Combined analysis of paleoenvironment, 13C, 15N, and 14C in bone, including paired dating of human bone and terrestrial materials (herbivore bone, wood, charcoal, and textile) has been performed on many samples excavated from Russian kurgan graves. The data can be used for dietary reconstruction, and reservoir corrections for 14C dating of human bone. The latter is essential for an accurate construction of chronologies for the Eneolithic and Bronze Age cultures of the Caspian steppes.

Santa Lucía is a pottery production site dating to the Formative period (about 1600 BC to AD 200). It is located in the Cochabamba valleys of the eastern Bolivian Andes. The settlement consists of a residential area and a separate workshop area. A peripheral sector of ash mounds was used as refuse sites and burial grounds. The excavations yielded a total of 16 radiocarbon samples from all 3 sectors, which were dated at the Gliwice Radiocarbon Laboratory (Gliwice, Poland). The results from the deepest trench in the workshop sector (Trench 5) provide information for the stratigraphic sequence and help to define spatial and socioeconomic changes at around 600–500 BC with the beginning of the Late Formative or Santa Lucía III phase. The 14C dates from Santa Lucía, therefore, contribute to a better definition of the existing regional Formative period phases and finally to a better understanding of the processes during the Formative period in the south-central Andes.

Complex interdisciplinary studies carried out in the territory of the Vilnius Lower Castle, E Lithuania, were used to construct a chronological framework based on radiocarbon data and archaeological information. Bulk samples (wood and sediment) were collected from an approximately 3-m core that crossed cultural layers and underlying strata. 14C dates indicate that the underlying bed possibly formed during the 6th century AD, although no archaeological finds were discovered there. Paleobotanical (pollen and plant macrofossil) investigations reveal evidence of agriculture that points to the existence of a permanent settlement in the area at that time. The chronological data indicates a sedimentation hiatus before the onset of the deposition of the cultural layer in the studied area. The 14C dates showed that the formation of the cultural bed began during the late 13th–early 14th centuries AD, that is, earlier than expected according to the archaeological record. The ongoing deposition of the cultural beds continued throughout the middle to latter half of the 14th century AD as revealed by the archaeological records and confirmed by well-correlated 14C results. After some decline in human activity in the middle of the 14th century AD, a subsequent ongoing development of the open landscape, along with intensive agriculture, points to an increase in human activity during the second half of the 14th century AD. The first half of the 15th century AD was marked by intensive exploitation of the territory, indicating a period of economic and cultural prosperity. The chronological framework indicates that the investigated cultural beds continued forming until the first half of the 16th century AD.

Many lacustrine chronology records suffer from radiocarbon reservoir effects. A continuous, accurate varve chronology, in conjunction with accelerator mass spectrometry (AMS) 14C dating, was used to determine the age of lacustrine sediment and to quantify the past 14C reservoir effect in Sugan Lake (China). Reservoir age varied from 4340 to 2590 yr due to 14C-depleted water in the late Holocene. However, during the Little Ice Age (LIA), 14C reservoir age was relatively stable. According to this study, 14C reservoir age in the late Holocene may be driven by hydrological and climatic changes of this period. Therefore, special caution should be paid to the correction of the 14C reservoir effect by a unique 14C reservoir age in paleoclimatic and paleolimnological study of northwest China.

Glacier fluctuations and paleoclimatic oscillations during the Late Quaternary in Val di Rabbi (Trentino, northern Italy) were reconstructed using a combination of absolute dating techniques (14C and 10Be) and soil chemical characterization. Extraction and dating of the stable fraction of soil organic matter (SOM) gave valuable information about the minimum age of soil formation and contributed to the deciphering of geomorphic surface dynamics. The comparison of 10Be surface exposure dating (SED) of rock surfaces with the 14C ages of resilient (resistant to H2O2 oxidation) soil organic matter gave a fairly good agreement, but with some questionable aspects. It is concluded that, applied with adequate carefulness, dating of SOM with 14C might be a useful tool in reconstructing landscape history in high Alpine areas with siliceous parent material. The combination of 14C dating of SOM with SED with cosmogenic 10Be (on moraines and erratic boulders) indicated that deglaciation processes in Val di Rabbi were already ongoing by around 14,000 cal BP at an altitude of 2300 m asl and that glacier oscillations might have affected the higher part of the region until about 9000 cal BP. 10Be and 14C ages correlate well with the altitude of the sampling sites and with the established Lateglacial chronology.

Recent comparative studies have proven the validity of radiocarbon dates of cremated bones. The issue of sample contamination has, however, been overlooked in most studies. Analyses of cremated bone samples has shown that in some cases, cremated bones are contaminated. This contamination is more distinct near the surface of the bones and depends on the compactness of the cremated bone as well as on the site conditions. δ13C is not a good estimator to discriminate between contaminated and uncontaminated bones. An acetic acid pretreatment is the most appropriate method to clean samples, but it is better to remove the surface and to avoid cremated bones that are not entirely white (cremation temp. <725 °).

Since the early Middle Ages, relics of Catholic saints played an important role in popular religion in Europe. The shrines containing the human remains of the saints, however, are rarely studied, typically only when restoration becomes necessary. Formerly, such study was mostly restricted to the art-historical aspects of the artifacts, sometimes including the counting and rough identification of the bones. In this study, for the first time, and for a number of case studies, a more systematic approach was taken, including detailed physico-anthropological observations, 13C and 15N stable isotope measurements, and 14C analysis of the bones.

The importance of this project lies not only in a critical evaluation of the authenticity of the relics. Fruitful insights could also be gained about the origin, history, and treatment of these parts of our religious heritage. Finally, it has been proven that shrines are an important source of early medieval human skeletal material, which is only rarely found in archaeological contexts in Belgium.

Since the publication of the first article (Lanting and van der Plicht 2001/2002) about the possibilities of dating cremated bones, the number of dated cremation remains has grown exponentially. The success of this dating technique lies in the fact that an absolute date now can be attributed to archaeological phenomena that previously were only datable indirectly. When archaeological artifacts where present, the cremation burials were dated based on the typology of ceramics and metals. An absolute date could be attributed if charcoal from the pyre were present. Unfortunately, these items were not omnipresent at the burial sites. Consequently, a complete site was dated by means of the few datable burials present. This implies that the internal chronology of the site could not be studied. Furthermore, the typochronology of the ceramics and the metals remains questionable. A series of dating projects on urnfield cemeteries in the Low Countries (northern France, Belgium, and the Netherlands) have shown that the classical chronology of these sites must be revised.

Over the past decade, radiocarbon dating of the carbonate contained in the mineral fraction of calcined bones has emerged as a viable alternative to dating skeletal remains in situations where collagen is no longer present. However, anomalously low δ13C values have been reported for calcined bones, suggesting that the mineral fraction of bone is altered. Therefore, exchange with other sources of carbon during heating cannot be excluded. Here, we report new results from analyses on cremated bones found in archaeological sites in Africa and the Near East, as well as the results of several experiments aiming at improving our understanding of the fate of mineral and organic carbon of bone during heating. Heating of modern bone was carried out at different temperatures, for different durations, and under natural and controlled conditions, and the evolution of several parameters (weight, color, %C, %N, δ13C value, carbonate content, crystallinity indexes measured by XRD and FTIR) was monitored. Results from archaeological sites confirm that calcined bones are unreliable for paleoenvironmental and paleodietary reconstruction using stable isotopes. Experimental results suggest that the carbon remaining in bone after cremation likely comes from the original inorganic pool, highly fractionated due to rapid recrystallization. Therefore, its reliability for 14C dating should be seen as close to that of tooth enamel, due to crystallographic properties of calcined bones.