Lakes worldwide are deteriorating due to climate change and other human impacts. Specifically, low dissolved oxygen levels are threatening food webs and water security. Protection, mitigation, and future projections of these phenomena call for a better understanding of their past evolution. For decades, paleolimnology has provided information about past environments by studying sediment structure and geochemistry. Among the latter, iron (Fe) and manganese (Mn), and their ratios are well-established proxies of the past water oxygenation. However, the understanding of redox-sensitive elements' mobility calls for a still scarce use of spatial approaches, complementing typical investigations focused on temporal geochemical variability. To address that, we began with 33-month-long observations of limnological conditions (water temperature and dissolved oxygen concentration) in a small, deep lake experiencing seasonal anoxia, continued with characterization of major sediment structures, and concluded with geochemical and statistical analyses of collected material. We used 31 surface samples from different depths and investigated their sediment structures, bulk geochemistry (CNS and biogenic silica), elemental composition (micro-X-ray fluorescence), and Fe and Mn fractions. Our data indicate clear, testable links between oxygen availability and sediment structures, as well as their chemical composition. Anoxia promotes the formation and preservation of laminations. Whereas seasonally migrating oxycline drives geochemical focusing, enriching the deepest sediments in Fe and Mn. This proves that both Fe and Mn are reliable indicators of deep-water redox conditions. Our study bridges modern limnology and paleolimnology and emphasizes the need to treat lakes and their sediments as a complete, complex system.
The Schöningen 13II-4 archaeological site in Germany holds title to the most complete Paleolithic wooden hunting spears ever discovered, yet its age has never been properly settled. Initial estimates placed the site at around 400,000 years; this age was later revised to roughly 300,000 years. Here, we report age estimates for the "Spear Horizon" based on amino acid geochronology of fossils obtained directly from the find-bearing deposits. Together with a reassessment of regional Middle Pleistocene chronostratigraphy, these data place the Schöningen spears at ~200,000 years. This revised age positions the Spear Horizon alongside other sites that collectively record a shift toward communal hunting strategies. The Schöningen archaeological record exemplifies this behavioral transformation that arose within the increasingly complex social environments of Middle Paleolithic Neanderthals.
Der Vergleich von Keramik des Jung- und Spätneolithikums im mitteldeutschen Raum steht im Fokus der vorliegenden Studie. Hierfür wird die Herstellungsweise von Keramikinventaren aus der Michelsberger Kultur derjenigen der chronologisch folgenden Wartberg-Gruppe von den Siedlungsplätzen Warburg-Ossendorf ’Gaulskopf‘, Kr. Höxter, und Wittelsberg, Fpl. 7, Lkr. Marburg-Biedenkopf, gegenübergestellt. Anhand von Dünnschliffuntersuchungen der Keramik zeichnet sich um 3000 v. Chr. ein Bruch in der Keramikentwicklung ab, der mit weiteren gesellschaftlichen Transfor- mationsprozessen korreliert.
An extensive drilling campaign to reconstruct a Neolithic landscape in the Ahlen-Falkenberger Moor in northwest Germany made it possible to document a cultural layer beneath a thick layer of bog peat formed by settlement activities, forest pasture or livestock grazing (site Wanna 1603). First excavations revealed finds that correspond to the typical spectrum of a settlement site. Both the typological and the absolute chronological dating, show that it was used between 3300 and 3000 cal BC and is therefore associated with the Funnel Beaker culture (TRB). This makes the site one of the few proven settlements with a preserved cultural layer in the TRB West group. In addition to the archaeological investigations, pedological, botanical and geological studies were also carried out. This made it possible to trace the development of the former coastline, the nearby wetlands and the successive covering of the site by bog peat. A large number of boreholes also made it possible to record the spatial extent of the site. Thus, landscape changes presumably triggered by human use could be identified. The temporal proximity of the settlement and land use to the changes in the landscape also indicates that the choice of settlement site was influenced by the latter. In sum, our research shows that in Wanna 1603 people of the TRB settled near a group of megalithic tombs on an island or pen insula in wetlands.
Reliable quantitative vegetation reconstructions for Europe during the Holocene are crucial to improving our understanding of landscape dynamics, making it possible to assess the past effects of environmental variables and land-use change on ecosystems and biodiversity, and mitigating their effects in the future. We present here the most spatially extensive and temporally continuous pollen-based reconstructions of plant cover in Europe (at a spatial resolution of 1° × 1°) over the Holocene (last 11.7 ka BP) using the ‘Regional Estimates of VEgetation Abundance from Large Sites’ (REVEALS) model. This study has three main aims. First, to present the most accurate and reliable generation of REVEALS reconstructions across Europe so far. This has been achieved by including a larger number of pollen records compared to former analyses, in particular from the Mediterranean area. Second, to discuss methodological issues in the quantification of past land cover by using alternative datasets of relative pollen productivities (RPPs), one of the key input parameters of REVEALS, to test model sensitivity. Finally, to validate our reconstructions with the global forest change dataset. The results suggest that the RPPs.st1 (31 taxa) dataset is best suited to producing regional vegetation cover estimates for Europe. These reconstructions offer a long-term perspective providing unique possibilities to explore spatial-temporal changes in past land cover and biodiversity.
