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Subfossil trunks of pine (Pinus sylvestris L.) from the Late Weichselian were discovered in the site Koźmin in the Koło Basin, central Poland (Dzieduszyńska et al., 2014a). Another part of organic sediments with trunks was excavated in the frame of the research project. Altogether 224 samples from Koźmin were analysed dendrochronologically; they represented generally young trees, 40 to 70 years old. Based on the most convergent sequences, the chronology 2KOL_A1 was produced, 210 years in length. With the wiggle-matching method, it was dated to ca. 13065–12855 cal BP. Dendrochronological dating of trunks buried in organic sediments, most of which occurred in situ, revealed that tree deaths occurred successively, over more than 100 years. That could have been due to unfavourable climatic conditions, as well as extreme events, e.g. strong winds.

An analysis was performed on samples from a series of well-preserved tree trunks and in situ stumps of Allerod/Younger Dryas age found in Koźmin and Kwiatkow, Kolska Basin, Central Poland. Five different types of wood preparation methods were investigated in three Polish radiocarbon laboratories (Gliwice, Poznan and Krakow) in order to find the most stable, repeatable and reliable procedure. Their effect was tested on the stable carbon isotope ratio (δ13C) and 14C age. Additionally, FTIR spectroscopy was used as a simple technique for obtaining rapid information on the structure of wood constituents and chemical changes taking place in wood due to various chemical treatments. The results of AMS measurements did not show statistically significant differences in radiocarbon ages of samples prepared according to the tested methods. On the other hand, δ13C measurements showed that the smallest scattering results gave α-cellulose obtained by the method BABA + Bleaching (with NaClO2 and HCl) + strong base. Moreover, the mean δ13C values for holo-cellulose samples are higher than those for α-cellulose samples. Studies evidenced that the methods of preparation leading to holo- or α-cellulose gave the same FTIR spectra, while the standard method of the chemical pretreatment of samples for 14C measurements (ABA) preceded by mercerization is insufficient for removing compounds containing aromatic rings.

Our project aimed to construct a Scots Pine (Pinus sylvestris L.) chronology for part of the Late Glacial and reconstruct changes in the 14C concentrations during this period. Kwiatków (Kolska Basin, central Poland) proved to be very prospective site, in which wood from the end of Allerød was recognized. A level of organic deposits with so-called fossil forest was encountered within the late-Vistulian terrace of the low valley of the Warta river. Dendrochronological analysis of over 267 samples complying to the requirements of the method allowed, at the present stage of the research, to construct a chronology spanning 265 yr. Fifty-two samples (5 consecutive rings each) were subjected to α-cellulose extraction and 14C measurements. Ninety-six results and the wiggle-matching technique anchor the chronology to the period 13,821–13,561 cal BP (Acomb=141.6%) according to the D_Sequence procedure and the IntCal13 calibration curve or to 13,800–13,540 cal BP according to the wiggle-matching technique using the χ2 test and raw data, i.e. the Heidelberg tree-ring sequence.

About 70% of the last cold stage was taken by transitional phases of continuous fluctuations of climate and permafrost extension. All this is reflected especially well in slope types and the thickness of slope, fluvial and aeolian deposits. Very distinct and relatively fast changes took place around 33–30 ka BP: the aridification of climate with an ice sheet transgression, expansion of continuous permafrost and the onset of loess deposition. The greatest transformations of slopes and river valleys in the Carpathians and Subcarpathian Basins took place not in the coolest phases but during the Interpleniglacial. The authors exemplified a number of sites in Southern Poland documenting frequent fluctuations of climate and permafrost from that 25–30 ka long period. Calibrated dates of dated episodes correlate well with the δ18O curve from Greenland with frequent warmings. These rapid warmings are reflected in the higher rate of aggradation in valley floors and thick colluvial material deposited over slopes, both combined with a retreat of permafrost. The comparison with the Greenland 18O curve is valuable to establish a comparable chronology of events, even for such a distant area like Central-Eastern Europe.

We reconstructed 3300 years (3500 BCE and 200 BCE) of the development history of the Rąbien peatland located in central Poland, using pollen, macrofossil, testate amoebae, Cladocera, Chironomidae and geochemistry. Central Europe, particularly Poland, is characterised by a transitional climate that is influenced by continental and Atlantic air masses, which makes this region very sensitive to climate change. Our results demonstrate the high potential of the Rąbien peat record to reconstruct palaeohydrological dynamics. The studied time interval is characterised by two pronounced dry periods: from ~ 2500 to ~ 1700 BCE and from ~ 700 to ~ 500 BCE, and two significant increases in the water table: from ~ 1000 to ~ 800 BCE and from ~ 500 to ~ 250 BCE. The timing of the wet shift at 600 BCE corresponds to wet periods at different sites in Central and Eastern Europe. Our investigation reveals a more complicated and complex than previously assumed set of climatic relationships in Europe between 3500 BCE and 200 BCE, which might be linked through complex teleconnections of atmospheric circulation patterns. Only reconstructions that are based on an understanding of current observations from peatlands and lake ecosystems may lead to a better interpretation of past climate changes.

High-resolution biological proxies (pollen, macrofossils, Cladocera and diatoms), geochemical data (μ-XRF element scans, TOC, C/N ratios, δ 18 O carb and δ 13 C org values) and a robust chronology based on varve counting, AMS 14 C dating and tephrochronology were applied to reconstruct lake system responses to rapid climatic and environmental changes of the Trzechowskie palaeolake (TRZ; Northern Poland) during the late Allerod – Younger Dryas (YD) transition. Palaeoecological and geochemical data at 5–15 years temporal resolution allowed tracing the dynamics of short-term shifts of the ecosystem triggered by abrupt climate change. The robust age control together with the high-resolution sampling allowed the detection of leads and lags between different proxies to the climate shift at the Allerod-Younger Dryas transition. Our results indicate (1) a water level decrease and an increase in wind activities during the late Allerod and the Allerod-YD transition, which caused intensified erosion in the catchment, (2) a two-decades delayed vegetation response in comparison to the lake depositional system. Comparison with the Lake Meerfelder Maar record revealed slightly different vegetation responses of the Trzechowskie palaeolake at the YD onset.

An age-depth model based on radiocarbon dates was produced from a Holocene profile collected from a rich fen situated in the Beskid Sądecki Mountains (the Outer Western Carpathians, southern Poland). The model is compared against the results of palynological and loss on ignition (LOI) analyses supplemented by the identification of organic deposits. Five distinct palynological episodes are detected. These potential palynological age markers are critically compared with the results of age-depth modeling and other dated profiles. The results presented distinctly show that using palynological episodes as age markers for age-depth construction may be highly misleading. DOI: 10.2458/azu_js_rc.55.16308

A simplified model of hydrological changes during the Late Glacial and Holocene is presented for the northern Polish regions that were ice covered during the Last Glacial. This reconstruction is based on a group of 197 radiocarbon dates from about 120 localities reflecting the sequence of alternating lake transgressions and regressions. The earliest transgressions were related to dead-ice melting (sometimes in 2–3 phases), while the later ones started during more humid phases. However, these were usually followed by regressions, which may have been connected with the formation of new drainage systems and with the overgrowing of shallow lakes by peat bogs. DOI: 10.2458/azu_js_rc.55.16343

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.

Archaeological excavations at the Syrian settlement of Tell Qaramel have been conducted since 1999. They are concentrated on remnants of the Protoneolithic and early stages of the Pre-Pottery Neolithic period. The settlement has revealed an extremely rich collection of everyday use of flint, bone, and mostly stone objects, such as decorated chlorite or limestone vessels; shaft straighteners used to stretch wooden arrow shafts, richly decorated in geometrical, zoomorphic, and anthropomorphic patterns; as well as different kinds of stones, querns, mortars, pestles, grinders, polishing plates, celts, and adzes.Excavations brought the discovery of 5 circular towers. Some 57 charcoal samples were collected during the excavations and dated in the GADAM Centre in Gliwice, Poland. The stratigraphy of the settlement and results of radiocarbon dating testify that these are the oldest such constructions in the world, older than the famous and unique tower in Jericho. They confirm that the Neolithic culture was formed simultaneously in many regions of the Near East, creating a farming culture and establishing settlements with mud and stone architecture and creating the first stages of a proto-urban being.

Carbonate binders from mortars and plasters as well as charcoal fragments sampled at the ancient settlement of Hippos (Sussita) have been subjected to radiocarbon dating by gas proportional counting (GPC) and accelerator mass spectrometry (AMS). Hippos is situated on the east coast of the Sea of Galilee (32°46′N, 35°39′E) at the top of a hill in the Golan Heights area, Israel. According to historical-archaeological data, the town had functioned since the 3rd century BC until AD 749, when it eventually crumbled into ruins after an earthquake. The appropriate sample selection and preparation based on the results of petrographic observations permitted us to distinguish different phases involved in the expansion of the settlement. More than 200 samples were taken from the settlement and subjected to petrographic and chemical analyses. Of the 200 total samples, about 20 were selected for dating. Here, we present the first 10 results of 14C dating carried out for Hippos. The oldest sample dated thus far gave an age corresponding with the 2nd century BC to 1st century AD—probably indicating an old Roman temple, on the base of which the North-West church (NWC) was later erected. The next dates extend up to the 8th century AD, the age related to the last phase of settlement inhabitation. Research is continuing as new excavations take place.

We report on a statistical analysis of a large set of radiocarbon dates for reconstruction of paleoclimate. Probability density functions were constructed by summing the probability distributions of individual 14C dates. Our analysis was based on 2 assumptions: 1) The amount of organic matter in sediments depends on paleogeographical conditions; 2) The number of 14C-dated samples is proportional to the amount of organic matter deposited in sediments in the examined time intervals. We quantified how many dates are required to give statistically reliable results. As an example, 785 peat dates from Poland were selected. The dates encompassed the Holocene and Late Glacial period. All dates came from the Gliwice Radiocarbon Laboratory. Results were compared with other paleoenvironmental records. Detailed analysis of the frequency distributions showed that preferential sampling plays an important part in the shape determination. The general rule to take samples from locations where visible changes of sedimentation are apparent (e.g. from the top and the bottom of the peat layer) results in narrow peaks in the probability density function near the limits of the Holocene subdivision.

Current calibration methods for single and replicate 14C dates are compared. Various forms of tabular and graphic output are discussed. Results from all the methods show reasonable agreement but further methodological development and improvements in computer output are required. Comparison of existing techniques for a series of non-contemporaneous dates showed less agreement amongst participants on this issue. We recommend that calibrated dates should be presented as a combination of graphs and ranges, in preference to mean and standard deviation.

Large sets of radiocarbon dates of 1019 peat, 155 speleothem, and 100 tufa samples, as well as dates of 330 fluvial samples, were investigated in order to estimate environmental variability during the last 16,000 calendar years in Poland. All 14C dating was carried out in the Gliwice Radiocarbon Laboratory, and results are stored in the RoS database. Probability density functions (PDFs) were created by summing up (on the calendar timescale) individual age probability distributions of all dates for different types of material and for different regions of Poland. We used an updated version of the Gliwice Radiocarbon Laboratory calibration program GdCALIB. The 14C dates were calibrated using the IntCal04 calibration curve (Reimer et al. 2004), and results were compared with other paleoenvironmental records. The authors conclude that analyzing PDFs of different types of sediments can be helpful in the qualitative reconstruction of the past environment. The PDF for peat samples primarily reflects paleohydrological conditions; the PDFs for speleothem and tufa samples reflect changes in temperature and humidity, while analysis of the PDF created for fluvial data is in a general agreement with the PDFs constructed for peat samples.