Irka Hajdas

Last Name

Hajdas

First Name

Irka

ORCID

0000-0003-2373-2725

Organisational unit

08619 - Labor für Ionenstrahlphysik (LIP) / Laboratory of Ion Beam Physics (LIP)

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Publications 1 - 5 of 5

Radiocarbon Dating of Dolomitic Mortars from the Convent Saint John, Müstair (Switzerland): First Results
Caroselli, Marta; Hajdas, Irka; Cassitti, Patrick (2020)
Radiocarbon
The monastery of St. John in Müstair, a UNESCO world heritage site, preserves archaeological remains and stone structures dated from the 8th century to the present. It has been extensively studied archaeologically so that numerous samples of historical materials, including mortar, are available for study. In addition to that, some of the structures have been precisely dated with dendrochronology. The monastery is located in a region characterized by dolomite rocks and the mortars are therefore of dolomitic nature, being perfectly suited to test the possibility of being dated with 14C. Furthermore, the presence of embedded carbon fragments has provided additional independent data to support or deny the results of mortar dating. A comparison of the results obtained from radiocarbon (14C) dating of bulk mortars, sieved fractions enriched in binder, lime lumps and carbon fragments, for two samples is presented, in relation to the petrographic characterization and the mineralogical phase content. This preliminary study shows that the dating of 14C can potentially be applied to the mortar of Müstair, as results in accordance with the established chronologies have been obtained for one sample. However, if the dolomitic sand contamination is very high, further studies are needed to develop a specific sample preparation technique. © 2020 by the Arizona Board of Regents on behalf of the University of Arizona.
A Later Stone Age quartz knapping workshop and fireplace dated to the Early Holocene in Senegal: The Ravin Blanc X site (RBX)
Pruvost, Charlotte; Huysecom, Eric; Garnier, Aline; et al. (2025)
PLoS ONE
Well-dated and well-preserved Later Stone Age sites are unfortunately scarce in West Africa. The few known ones exhibit significant typo-technical variability, reflecting diverse socio-cultural behaviors that remain poorly understood. The Ravin Blanc X (RBX) site in eastern Senegal provides new insights into this period. Excavations at one of the sectors of the site (RBX-1) have revealed a well-preserved Early Holocene occupation, featuring a quartz knapping workshop associated with a fireplace. This site is the latest known LSA occupation in the Falémé valley and bridges a critical gap in the region’s prehistoric sequence. The lithic industry at RBX-1 is dominated by a very homogeneous quartz, which was specifically selected for its high-quality knapping properties. Two main categories of sought blanks were produced: broad, thick, and rectilinear blanks, and elongated, thin and narrow blanks with an oblique distal termination forming a natural asymmetric point. The strong investment in blank standardization from the extraction stage significantly reduced the need for subsequent retouching, which was rarely observed in the RBX-1 lithic assemblage. Comparisons with other LSA sites in West Africa suggest that RBX-1 shares technological similarities with the sites of Fatandi V (Falémé valley, Senegal) and Damatoumou 1 (Ounjougou, Mali), possibly indicating a West African Late LSA Sahelo-Sudanian facies. In contrast, sites located in Guineo-Congolian forest contexts exhibit different knapping strategies and typological choices. The discovery of RBX-1 enhances our understanding of the LSA in West Africa by providing a rare, well-dated stratigraphic context (around 9100 calBP/7100 calBCE) which highlights the complexity of regional lithic traditions and raises new hypotheses about cultural transitions during the Pleistocene-Holocene shift.
Ancient DNA and dating evidence for the dispersal of hippos into central Europe during the last glacial
Arnold, Patrick; Döppes, Doris; Alberti, Federica; et al. (2025)
Current Biology
Late Pleistocene hippo fossils (Hippopotamus amphibius) from Europe have generally been associated with the last interglacial period (Eemian, 129-115 thousand years ago [kya]). As a widely accepted indicator species for temperate climate conditions, it was assumed they went extinct with the onset of the last glacial (Weichselian) around 115 kya. Their origin and relationships to extant African common hippos and the exact age of their extinction in central Europe, however, remain unclear. Here, we address these questions using an integrated approach applied to hippos from the Upper Rhine Graben in central Europe. By sequencing the paleogenome of a European hippo, we reveal its close genetic links to modern hippos from Africa. Six additional partial mitochondrial genomes confirm that European representatives were part of the same, once widespread species that is today restricted to sub-Saharan Africa. Surprisingly, radiocarbon dating shows that hippos were present in central Europe during the middle Weichselian (a period spanning from earlier than 47 kya until ∼31 kya), i.e., well into the last glacial. Similar radiocarbon dates for woolly mammoth and woolly rhino fossils from the same sites imply the presence of both faunas during this period. Despite the paleogenome's low coverage, we are able to confidently estimate its genome-wide diversity by recalibrating the sequencing quality scores and assessing post-mortem damage. The low genome-wide diversity recovered suggests that it belonged to a small, isolated population. Overall, our combined data imply that hippos inhabited the Upper Rhine Graben refugium during temperate phases of the middle Weichselian.
Fading of the ¹⁴ C bomb peak – students’ project to observe the Suess effect
Irka Hajdas; André Albrecht; Danuta Michalska; et al. (2025)
Radiocarbon
Abstract The natural variability of atmospheric 14 C has been significantly altered by anthropogenic activities linked to technological advancements and energy consumption over the past two and a half centuries. The Suess effect, a consequence of the combustion of old carbon (fossil fuels) since the mid-18th century and the bomb peak from the mid-20th century’s thermonuclear tests, has obscured the natural 14 C signal in the atmosphere. This study presents a 14 C analysis of leaves, flowers, and grass collected from various locations worldwide. Over the last 10 years, more than 150 samples have been collected and used as materials for experiments conducted by students in physics lab classes (Department of Physics, ETH Zurich) or as part of school projects. Short-lived vegetal fragments are ideal material for teaching radiocarbon dating and demonstrating our research. The collection of data presented here underscores the sensitivity of radiocarbon analysis for detecting fossil carbon components. Trees from urban sites worldwide demonstrate a dilution of the atmospheric 14 C concentration of 2–3%. Trees growing close to busy roads and traffic show a dilution of up to 10%. Moreover, the data show a fading trend of the bomb peak observed from 2015 to the present, as well as the direct impact of fossil CO 2 on the 14 C concentration of the living biota around us.
Integrating Material Analysis, Radiocarbon Dating, and Technical Examination in the Dating and Provenance Study of a Copy of Raphael’s “The Great Holy Family of Francis I”
Ferreira, Ester S.B.; Hoffmann, Charlotte; Hendriks, Laura; et al. (2025)
Heritage
In 2016, five fragments from a copy of “The Great Holy Family of Francis I” were brought to the Cologne Institute of Conservation Sciences (CICS) for research and conserva-tion/restoration. A comprehensive technical and material analysis was carried out to as-sist provenance studies. From the analysis of pigments, binder, additives, and canvas fi-bres alongside radiocarbon dating of the lead white pigment, oil binder, and canvas sup-port, as well as the lead stable isotope study, it could be determined that, with high proba-bility, the copy was created in Northern Europe between the late 16th century and the mid-17th century. During this period the original painting was initially displayed in Fon-tainebleau in the “Chapelle Haute” before being transferred in the early 17th century to the newly built “Cabinet des Peintures”, also in Fontainebleau, where it would probably have been more accessible for copying. Interestingly, the written sources describe a copy made during this period to replace the original in the “Chapelle Haute”, the location of which is currently not known. However, the different overall dimensions of the present copy speak against it, having been created to replace the original.

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Irka Hajdas

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