INTRODUCTION
The paper presents the results of radiocarbon (14C) dating commissioned in 2018 and 2019 by the University of Gdańsk to the Poznań Radiocarbon Laboratory (PRL) and the Oxford Radiocarbon Accelerator Unit (ORAU) within the project mentioned in the title. Only a part of the results of the measurements has been already used in chronometric studies contributing to the project (Chmielewski et al. Reference Chmielewski, Hałuszko, Goslar, Cheronet, Hajdu, Szeniczey and Virag2021a, Reference Chmielewski, Hałuszko, Mackiewicz, Pieńkos, Sady-Bugajska, Starkova and Ślusarska2021b). However, even they remain underreported. Therefore, in order to facilitate further research that may be based on the measured radiocarbon ages, we decided to provide their complete list with comprehensive comments.
MATERIALS
All samples used for the reported 14C age measurements come from archaeological sites located in the area of Dobużek Scarp, on the Sokal Ridge in eastern Poland (Figure 1).
Figure 1 Archaeological sites identified on the paha of the Dobużek Scarp with the location of features that yielded the reported radiocarbon dates (DKK—Dobużek Kolonia, MKN—Mikulin). General geographical location of the Dobużek Scarp (E Poland) in Central Europe is provided in the lower right corner. Digital processing by M. Mackiewicz
The scarp lies in the Lublin Voivodeship, Tomaszów Lubelski County, in the borderland of Tyszowce and Łaszczów Communes (geographic coordinates: 50°34ʼ55"N and 23°42ʼ56"E). It is a distinctive physiographic feature of the central part of the Sokal Ridge, i.e., one of three mesoregions of the westernmost part of the Volhynian Upland. The scarp constitutes some 2 km long and up to 40 m high along the right bank of the Huczwa river valley. The escarpment is topped by a loess greda, which culminates close to the edge of the valley and then gently slopes northwards, towards an unnamed watercourse feeding the Huczwa river.
The zone of well-confirmed prehistoric settlement and activity is limited to the southern part of the loess mantle of the paha, which forms a plateau there with small elevation differences. The remains of the settlement and other prehistoric activity recorded on the scarp can be archaeologically dated to the period that starts with the Eneolithic and ends with the Early Iron Age.
The 14C age determinations related to the prehistoric settlement were obtained for 39 samples (two of which were divided into two subsamples of different codes) derived from 30 features discovered on 6 archaeological sites located on the loess paha. The set of samples submitted for dating consisted mostly of human and animal bones. Only in a few instances were charcoals and charred fragments of annual plants (cereals and grasses) used.
METHODS
The majority of samples were dated with the accelerator mass spectrometry (AMS) 14C method at PRL (Goslar et al. Reference Goslar, Czernik and Goslar2004), except for two samples, which were dated at ORAU for the purpose of interlaboratory cross-check.
For most bone samples, the dated fraction consisted of collagen extracted using the Longin method (1971) supplemented by removal of humic substances with NaOH and purified by ultrafiltration (Bronk Ramsey et al. Reference Bronk Ramsey, Higham, Bowles and Hedges2004; Brock et al. Reference Brock, Higham, Ditchfield and Bronk Ramsey2010). The state of preservation of collagen in bones was preliminarily assessed by analyzing C and N percentages (using the ThermoScientific analyzer Flash EA 1112 Series).
Samples of charcoal or other plant remains (after mechanical removal of macroscopic contamination visible under binocular), were treated with the common AAA (acid-alkali-acid) procedure (Brock et al. Reference Brock, Higham, Ditchfield and Bronk Ramsey2010).
Aliquots of collagen or plant remains pretreated with AAA were then combusted in a “Scientific” Elemental Analyser and graphitized in automated equipment AGE 3 (produced by Ionplus AG, Switzerland). The elemental analyzer measured also C and N percentages, thus allowing, for instance, to indicate collagen quality by the means of atomic C/N ratio (van Klinken Reference van Klinken1999).
The samples smaller than 1 mg of C were combusted in closed (sealed under vacuum) quartz tubes, together with CuO and Ag wool, in 900°C for over 10 hr, and the obtained CO2 was graphitized with hydrogen (H2), using Fe powder as the catalyst. All graphites were analyzed for 14C in the “Compact Carbon AMS” spectrometers (Goslar et al. Reference Goslar, Czernik and Goslar2004).
Cremated bones, in which no collagen was preserved, were processed according to Lanting et al. (Reference Lanting and van der Plicht2001). The preparation process concluded with leaching in H3PO4 to retrieve carbon from the structural carbonate (apatite) fraction. As recommended, for instance by Pustovoytov and Riehl (Reference Pustovoytov and Riehl2006), acid leaching was applied also to the sample of Lithospermum sp. The CO2 retrieved by acid-leaching was further processed like CO2 from the combustion of small organic samples.
In order to obtain dates of possibly high precision, the measurements for 6 samples were repeated, while for one, even three measurements were performed. All measurements are reported in line with currently recommended standards (cf. Millard Reference Millard2014: 681–690; Bayliss Reference Bayliss2015). Calibration of resulting radiocarbon ages in regard to the IntCal20 curve (Reimer et al. Reference Reimer, Austin, Bard, Bayliss, Blackwell, Ramsey, Butzin, Cheng, Edwards, Friedrich, Grootes, Guilderson, Hajdas, Heaton, Hogg, Hughen, Kromer, Manning, Muscheler, Palmer, Pearson, van der Plicht, Reimer, Richards, Scott, Southon, Turney, Wacker, Adolphi, Büntgen, Capano, Fahrni, Fogtmann-Schulz, Friedrich, Köhler, Kudsk, Miyake, Olsen, Reinig, Sakamoto, Sookdeo and Talamo2020) was completed with the use of the OxCal 4.4 package (Bronk Ramsey Reference Bronk Ramsey2009).
RESULTS
A total of 46 successful measurements of 14C age were completed (see Supplementary Material 1). After excluding a single sample of the modern age (Poz-104777), all the obtained 14C dates fall into the interval 4045–415 yr cal BC (68.3%; rounded by 5 yr) that can be correlated with the Subboreal. Within the likelihood density distribution, there are three distinct peaks corresponding with the Middle-Late Eneolithic, the decline of the final Eneolithic to the beginning of the Bronze Age, and the end of the Bronze Age to the beginning of the Early Iron Age (Figure 2) as could be anticipated on the basis of assessment of archaeological contexts of the samples (More detailed comments on the adequacy of particular age determinations are provided separately [see Supplementary Material 2]).
Figure 2 The sum distribution of calibrated 14C likelihood distributions (SUM) and the kernel density estimation (KDE) of the underlying distribution of the prehistoric settlement events recorded on the paha of the Dobużek Scarp. Digital processing by T.J. Chmielewski.
CONCLUSIONS
The comprehensive and final results of 14C age measurements made under the project “The Dobużek Scarp Microregion as a part of a physiological and biocultural frontier between the Baltic and the Pontic zone (from the 6th to the 2nd millennium BC)” are presented above. Therefore, the report can be cited as the main source of information on the measurements and the resulting 14C dates. Moreover, since the chronometric outcomes of the project are published, whomever it may concern is free to exploit related data and resources (such as collagen extracted from bones) available in PRL and ORAU for further scientific investigation.
ACKNOWLEDGMENTS
All fieldworks and post-ex analyses were funded by National Science Centre, Poland (Project No. 2015/18/E/HS3/00754). We would like to express our gratitude to the following Colleagues who conducted excavations that yielded all the archaeological material submitted for the radiocarbon age measurements: Jolanta Bagińska and Łukasz Wyszyński (Regional Museum of dr. Janusz Peter, Tomaszów Lubelski), Mateusz Krupski, Maksym Mackiewicz, Bartosz Myślecki (Wrocław), Igor Pieńkos (Igor Pieńkos INGWAR, Jędrzejów), Katarzyna Ślusarska (Institute of Archaeology and Ethnology, University of Gdańsk, Gdańsk), and Paweł Zawiślak (Lublin). We are also thankful for the assistance of Emma Henderson (ORAU), who kindly provided us with all the details of the radiocarbon age measurements made in the course of the project by her laboratory.
Supplementary material
To view supplementary material for this article, please visit https://doi.org/10.1017/RDC.2021.79
