High-resolution AMS (accelerator-mass-spectrometer) radiocarbon dating was performed on late-glac... more High-resolution AMS (accelerator-mass-spectrometer) radiocarbon dating was performed on late-glacial macrofossils in lake sediments from Kodiak Island, Alaska, and on shells in marine .sediments from southwest Sweden. In both records, a dramatic drop in radiocarbon ages equivalent to a rise in the atmospheric 14C by-70%0 coincides with the beginning of the cold period at 11 000 yr B.P. (14C age). Thus our results show that a close correlation between climatic records around the globe is possible by using a global signature of changes in atmospheric 14C content. INTRODUCTION Radiocarbon chronologies of the last deglaciation reveal that climatic events of this period were accompanied by dramatic changes in atmospheric content of the cosmogenic radioisotope of carbon. An abrupt increase in
ABSTRACT Seit 2007 untersucht ein internationales Forschungsprojekt in der Silvretta zwischen der... more ABSTRACT Seit 2007 untersucht ein internationales Forschungsprojekt in der Silvretta zwischen der Schweiz und Österreich die Spuren der ersten Hirten. Dabei wird immer mehr die hohe Anzahl und Qualität alpiner Denkmäler aus mittlerweile 11 Jahrtausenden deutlich - von Lagern steinzeitlicher Jagdgruppen bis zur ältesten Alphütte der Schweiz.
HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific re... more HAL is a multidisciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers. L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.
This article presents a new suite of radiocarbon (14C) dates for the lower portion of the Late Br... more This article presents a new suite of radiocarbon (14C) dates for the lower portion of the Late Bronze Age (LBA) sequence of Area S, Tel Lachish. The results show that the lowest levels reached by Ussishkin in the 1980s (S-2 and S-3) date significantly earlier than was previously thought. Level S-3, with its monumental architecture, belongs in the 2nd half of the 15th century BCE, as does the commencement of Level S-2. The laminated deposit of S-2 continues through the first half of the 14th century BCE, coinciding at least in part with the Amarna period. This redating leads to improved agreement between archaeological and textual evidence regarding the presence of a substantial, prominent settlement at Lachish during LB IB-IIA, from the reign of Thutmoses III through the Amarna period.
Based on the results of geoarchaeological investigations carried out at the Czermno site (eastern... more Based on the results of geoarchaeological investigations carried out at the Czermno site (eastern Poland), which is associated with Cherven, i.e. the mediaeval capital of the Cherven Towns, we reconstructed the main stages of environmental changes and human impact in the surroundings of the site. The site is of great archaeological importance due to its historical context that is essential to identify the conditions of settlement formation in the Polish-Rus' borderland in the Middle Ages. The present study combines palaeoenvironmental and archaeological knowledge with chronostratigraphic data to infer the main stages of settlement, connected with the outset, functioning and collapse of the mediaeval capital of the Cherven Towns. The location of the site was analysed in the context of geological, geomorphological, climatic, hydrological and soil conditions as well as changes of the natural vegetation. An assessment was made of the anthropogenic transformation of the land relief and hydrological regime, which made it possible to reconstruct these components of the geographic environment in the period preceding the construction of the stronghold and the adjacent settlements. The results of our investigations show that, in the Middle Ages, (1) the climate was relatively cold and dry in the 7 th-8th century AD, when settlement activity started in the vicinity of the site (as affirmed by chronostratigraphic data) (2) intensive transformations of the landscape (i.e. adaptation for settlement), were carried out on a large scale during the subsequent seven centuries (land levelling, reorganization of drainage, i.e. the construction of moats, ramparts and a log-paved roads), (3) the human impact on the environment was particularly strong (as indicated by reliable multi-proxy data) in the mid-9th century AD, at the end of the 10th and turn of the 11th century AD, and in the second half of the 12th century AD, (4) all these settlement phases were connected with a relatively warm and humid climate.
A radiocarbon chronology of lake sediments deposited in Lake Wigry during the Last Glacial and Ho... more A radiocarbon chronology of lake sediments deposited in Lake Wigry during the Last Glacial and Holocene periods provided the basis for calendar age-depth modeling. Various fractions (organics and carbonates) were dated and the results were subjected to critical analysis. The dates affected by reservoir effects as well as outlying data were excluded, and the non-linear age model was developed based on 13 ages. The statistical tools used for construction of the models include the Bayesian analysis, applied for calibration of14C dates with regard to stratigraphical position of the samples, and generalized additive models (GAM).
One of the greatest challenges of contemporary archaeology is to synthesize the large amount of r... more One of the greatest challenges of contemporary archaeology is to synthesize the large amount of radiocarbon and archaeological data into a useful dialogue. For the late Epipaleolithic and the Early Neolithic of the Near East, many14C ages have been published without precise stratigraphic documentation. Consequently, for archaeological age models we often must use some more elementary approaches, such as probabilistic summation of calibrated ages. The stratigraphy of Körtik Tepe allows us for the first time to study an extended series of14C ages of the earliest Holocene. In particular, we are able to analyze the data according to stratigraphic position within a well-documented profile. However, because of a plateau in the14C age calibration curve at the transition from the Younger Dryas to the Early Holocene, dates of this period can be interpreted only if an extended sequence of dates is available. Due to problems remaining in the calibration procedure, the best way to achieve an in...
A detailed radiocarbon chronology has been established for the deep-sea core CT85-5 from the Tyrr... more A detailed radiocarbon chronology has been established for the deep-sea core CT85-5 from the Tyrrhenian Sea. This chronology, which is based on the analysis of foraminifera shells, shows a set of reversed14C ages for sediments deposited during the eruption of the Campanian Ignimbrite (∼40 ka cal BP). The anomalous young14C ages coincide with elevated concentrations of10Bc measured in the same core. Although reversals in14C ages have been previously found in other records at 40 ka cal BP, such extreme changes have not been observed elsewhere. The enhancement in14C concentration in CT85-5 sediments associated with the Campanian Ignimbrite is equivalent to an apparent age ∼15 ka younger than the age for the sediments deposited shortly before the eruption. Here, we present consistent results of repeated measurements showing no analytical problems that can explain the observed rapid changes in14C of this particular record.
Progressive dissolution experiments were performed on samples of ostracode shells from lacustrine... more Progressive dissolution experiments were performed on samples of ostracode shells from lacustrine sediments from the western Great Basin to remove contamination of the surface by secondary calcite. The observed age differences between the external and residual fractions were as great as 2000 to 6000 yr. A “plateau” in ages of the last fractions was obtained only for 1 sample; however, results of repeated experiments resulted in very good agreement of the final ages. A comparison with previously published chronologies based on bulk radiocarbon ages of ostracodes from Wilson Creek (Benson et al. 1990) shows that leaching is imperative for dating samples older than 20 ka B P. This study focuses on the problem of contamination and its removal. However, the final chronology of the Wilson Creek Formation (and other late Pleistocene lacustrine sediments) will require additional dating of other sections as well as establishment of a reservoir effect correction.
In this study, we test the possibility of using databases of radiocarbon ages to estimate boundar... more In this study, we test the possibility of using databases of radiocarbon ages to estimate boundaries of climatic chronozones. The Alaska region was chosen and compared with chronozones of 2 European countries: Poland and the Netherlands. The study included setting up a database of14C ages published for climatic records from Alaska. Some 97414C determinations on organic samples were selected and used to establish chronozones for the Late Glacial and the Holocene for the Alaska region. The selected data were calibrated and a summed probability density function (PDF) was calculated. The shape analysis of the constructed frequency distribution of14C dates on calendar timescales together with the assumption about preferential sampling seems to be a useful tool for establishing calendar ages for boundaries of climatic periods, i.e. chronozones.
Understanding of processes that determined the expansion of farming and animal husbandry in south... more Understanding of processes that determined the expansion of farming and animal husbandry in south-western Europe is hampered by poor chronologies of the early Neolithic in this region. This paper presents new radiocarbon dates, which are used to construct such a chronological frame for a regional group of the most important culture of the early Neolithic in the western Mediterranean: the Cardial culture.
The main force driving technical development of the radiocarbon dating technique is the wide spec... more The main force driving technical development of the radiocarbon dating technique is the wide spectrum of applications that cross interdisciplinary boundaries of Earth and social sciences. This paper provides a very brief overview of some of the many applications of 14C analysis to various studies of human origin and migration, cultures and history, past and present environment, and the human body itself.
Cold-water coral (CWC) ecosystems occur worldwide and play a major role in the ocean's carbonate ... more Cold-water coral (CWC) ecosystems occur worldwide and play a major role in the ocean's carbonate budget and atmospheric CO 2 balance since the Danian (~65 m.y. ago). However their temporal and spatial evolution against climatic and oceanographic variability is still unclear. For the first time, we combine the main macrofaunal components of a sediment core from a CWC mound of the Melilla Mounds Field in the Eastern Alboran Sea with the associated microfauna and we highlight the importance of foraminifera and ostracods as indicators of CWC mound evolution in the paleorecord. Abundances of macrofauna along the core reveal alternating periods dominated by distinct CWC taxa (mostly Lophelia pertusa, Madrepora oculata) that correspond to major shifts in foraminiferal and ostracod assemblages. The period dominated by M. oculata coincides with a period characterized by increased export of refractory organic matter to the seafloor and rather unstable oceanographic conditions at the benthic boundary layer with periodically decreased water energy and oxygenation, variable bottom water temperature/density and increased sediment flow. The microfaunal and geochemical data strongly suggest that M. oculata and in particular Dendrophylliidae show a higher tolerance to environmental changes than L. pertusa. Finally, we show evidence for sustained CWC growth during the Alleröd-Younger-Dryas in the Eastern Alboran Sea and that this period corresponds to stable benthic conditions with cold/dense and well oxygenated bottom waters, high fluxes of labile organic matter and relatively strong bottom currents PLOS ONE |
Ein erster Beleg für prähistorischen Bergbau im Oberhalbstein/GR (Schweiz)?
Seit Jahrzehnten sind zwischen Tiefencastel und dem Julierpass prähistorische Kupferverhüttungspl... more Seit Jahrzehnten sind zwischen Tiefencastel und dem Julierpass prähistorische Kupferverhüttungsplätze bekannt. Eine erste systematische Untersuchung dieser Fundplätze, der lokalen Erze und bronzezeitlichen Siedlungen mit Hinweisen auf Metallverarbeitung findet seit 2013 unter der Regie der Universität Zürich, Fachbereich Prähistorische Archäologie, in Kooperation mit dem Archäologischen Dienst Graubünden und der Universität Innsbruck statt. Aus der lokalen montanhistorischen Literatur waren Hinweise auf einen "eigenartigen Felsspalt" in steilem, schwer zugänglichem Felsgebiet nahe des Marmorera-Staudammes bekannt. Nach Hinweisen von Martin Schreiber gelang dem Forschungsteam im Sommer 2013 die Wiederentdeckung des nahezu unberührten Ortes: Schnell konnte festgestellt werden, dass es sich um einen feuergesetzten Stollen handelt. Etwa 2 m vor dem Stollort wurde eine Sondage angelegt. Nach einer Abtiefung von 60 cm wurden die Arbeiten vorerst eingestellt, da bereits zahlreich...
In a high altitude region such as the Silvretta Alps (Switzerland/Austria), past and extant settl... more In a high altitude region such as the Silvretta Alps (Switzerland/Austria), past and extant settlement activities are known to have had large influences on the alpine flora and vegetation. The Silvretta Massif harbors more than 230 archaeological sites above 2000 m a.s.l. on a total area of 550 km 2 , from the Mesolithic period to Modern Times, but received little attention in these matters up to recently. The Fimba Valley within the Silvretta area with 47 known archaeological sites (6 prehistoric, 21 from the Medieval and/or Modern Times, 20 undated) located over an area of 62 km 2 provides evidence of a broad range of former human presence, as well as peat records allowing the reconstruction of Holocene climatic change and anthropogenic impact on past vegetation. Here, we present a high resolution, multi proxy study (including pollen, cryptogam spores, and non pollen palynomorphs) on a 177 cm long radiocarbon dated peat core from the Las Gondas Bog in the Fimba Valley (2363 m a.s.l.). Palynological evidence adds and confirms previous dendrochronological results, revealing extensive high Pinus cembra (Arolla pine) stands around the bog at 10,400 cal BP and between ca. 8600 6700 cal. BP, more than 300 altitudinal meters above today's timberline, and belonging therefore to the highest population known for Central Europe. In addition, our palaeoecological results correlate well with the archaeologically known human impact during the Neolithic, Iron Age and Medieval periods. The exploitation of alpine landscape resources (cultivation of cereals in the valleys) and livestock grazing (in the subalpine and alpine areas) has therefore a long tradition going back at least for 6200 years in the Silvretta region.
The oasis of Samarkand in the Middle Zeravshan Valley (modern Uzbekistan) was a major political a... more The oasis of Samarkand in the Middle Zeravshan Valley (modern Uzbekistan) was a major political and economic center in ancient western Central Asia. The chronology of its irrigation system was, until now, only constrained by the quality and quantity of archaeological findings and several different hypotheses have been proposed for it. We use a new approach combining archaeological surveying, radiocarbon dating, sedimentary analysis, and the numerical modeling of a flood event to offer new evidence for, and quantitative dating of, the development of irrigation system on the southern flank of the Middle Zeravshan Valley. We analyzed 13 bones and charcoals from 3 archaeological sites and obtained new 14C ages from Afrasiab (ancient Samarkand), a dwelling damaged by flooding in the 2nd century AD (site code: SAM-174) and the fortress of Kafir Kala. We established the origin of sedimentary deposits at the sites to infer the presence of the 2 most important canals of the southern flank: t...
The IntCal09 and Marine09 radiocarbon calibration curves have been revised utilizing newly availa... more The IntCal09 and Marine09 radiocarbon calibration curves have been revised utilizing newly available and updated data sets from 14C measurements on tree rings, plant macrofossils, speleothems, corals, and foraminifera. The calibration curves were derived from the data using the random walk model (RWM) used to generate IntCal09 and Marine09, which has been revised to account for additional uncertainties and error structures. The new curves were ratified at the 21st International Radiocarbon conference in July 2012 and are available as Supplemental Material at www.radiocarbon.org. The database can be accessed at http://intcal.qub.ac.uk/intcal13/.
High-quality data from appropriate archives are needed for the continuing improvement of radiocar... more High-quality data from appropriate archives are needed for the continuing improvement of radiocarbon calibration curves. We discuss here the basic assumptions behind 14C dating that necessitate calibration and the relative strengths and weaknesses of archives from which calibration data are obtained. We also highlight the procedures, problems, and uncertainties involved in determining atmospheric and surface ocean 14C/12C in these archives, including a discussion of the various methods used to derive an independent absolute timescale and uncertainty. The types of data required for the current IntCal database and calibration curve model are tabulated with examples.
This article appeared in a journal published by Elsevier. The attached copy is furnished to the a... more This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright
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Papers by Irka Hajdas