CRC806-Database Publications Feed (Atom) Archaeology across the Pleistocene-Holocene boundary in western Germany: Human responses to rapid environmental change 2017-10-02T14:20:05+02:00 In recent years, new insights into the Mesolithic in the Rhineland and in Westphalia have been gained. The Early Mesolithic human remains of the Blätterhöhle in Hagen should especially be mentioned as they even attracted international attention. Additionally, a first stratigraphic sequence containing hearth remains and lithic assemblages of the Early to Late Mesolithic age has been excavated there. Further new sites and radiometric investigations on single finds suggest varying influences from northern and southern as well as western regions on the Northrhine-Westphalian Mesolithic. Several sites, which are assigned to the broad blade complexes or the long blade industries / the Belloisien due to the distinct blade technology and simple microlithic projectile points, represent the initial stage of the Mesolithic. Birgit Gehlen Conference report: The 26th Annual Meeting of the German Mesolithic Workgroup 2017-09-20T14:27:08+02:00 organised and hosted by Annabell Zander (University of York) and Birgit Gehlen (CRC 806, University of Cologne). In sum, more than 70 academics, students and amateur archaeologists from 8 different countries attended this conference. The international programme consisted of 24 talks and 10 poster presentations which were held in English and German. The presentations ranged from international to regional themes concerning the Final Palaeolithic, Mesolithic and Early Neolithic. Birgit Gehlen Foragers and Farmers during the Neolithic Transition in Western Central Europe: Searching for Evidence of Mobility and Intercultural Networks 2017-08-16T07:19:57+02:00 Introduction This paper discusses the interaction between foragers and farmers during the various phases of the neolithisation processes in south-western and north-western central europe. The disparate state of research on Late Mesolithic hunter-gatherer groups and early Neolithic farmers in terms of the certainty of the detailed chronology, the number of sites and the comprehensiveness of the find and feature analyses, does not permit a discussion on the basis of equally-weighted data. Nevertheless, examples can be found to illustrate and evaluate such interaction with regard to the questions raised in this volume on “Mobility in prehistoric sedentary societies”. important for the following discussions are the distribution maps (Figs. 2–4) and the sites of special interest (Fig. 1; list of sites in Appendix, p. 73). Birgit Gehlen Holocene Environmental History of Lake Chamo, South Ethiopia 2017-06-26T13:03:08+02:00 East African Rift Valley Lakes hold a rich source of information for palaeoclimate change. Specifically, the sediment archives of Lake Chamo, one of the Ethiopian Rift Valley Lakes, reveal short-term climatic fluctuations and environmental instability during the Holocene, since it is located in a temporary endorhëic system. Currently there are no substantial studies yet that investigate palaeoenvironmental history of Lake Chamo. The objective of this thesis is to reconstruct the Holocene climatic and environmental history of Lake Chamo at high temporal resolutions. The specific aim of the project is to estimate climate-driven and anthropogenic environmental change during the Holocene, and to test a hypothesis that there were rapid climate fluctuations during the termination phase of the “African Humid Period” (AHP). Initially, the first continuous and high-resolution geochemical and geophysical core data from the sediments of Lake Chamo using X-Ray Fluorescence (XRF) core scanner and Geotek Multi-Sensor-Core-Logger (MSCL) respectively, is presented. Using these techniques palaeoclimatic conditions of the region during the Holocene are reconstructed. Additionally, the core chronology is established using Accelerator Mass Spectrometry (AMS) radiocarbon analysis, the results of which show that the core dates back to 9000 cal yr BP. Early-Holocene can be seen to be characterised wetter climatic conditions as recorded from the relative lower lightness values, high Silicon to Titanium ratio (Si/Ti), and minimum calcium concentration in the sediment. Pronounced peak in calcium and Strontium content, which are the main features of the early-mid Holocene transition period, are ascribed to a high evaporation to precipitation ratio, implying the aridity of the region in this time frame. In addition, the peak values of magnetic susceptibility (MS), Potassium (K), Titanium (Ti), Silicon (Si), and Iron (Fe) during 1500–800 cal yr BP are found to be associated to a change in intensity of anthropogenic land use in the area surrounding the lake. Subsequently, the charcoal counting and detection of benzene polycarboxylic acids (BPCA) methods are implemented to estimate paleofire occurrence in relation to climatic and anthropogenic impact of Lake Chamo. These results are used to correlate the long term trends in fire occurrence in relation to climate, vegetation and human activities at different spatial and temporal scales. Fire occurrence was found to be higher during the early Holocene, typically identified through black carbon (BC) from woody or shrub vegetation sources. The occurrence of fire was found to be lower during the mid-Holocene, due to the presence of predominantly grass savannah which usually results in reduced biomass burning in response to drier condition. Climate and vegetation were found to be the main factors for fire occurrence during the early and mid Holocene, whereas the increased fire intensity since 2000 cal yr BP record is potentially attributed to anthropogenic forcing. Finally, ostracod analyses are used to gain evidence about climatic and hydrological instability of southern Ethiopia during the Holocene. The ostracod study focuses on the taxonomy, stratigraphy and the use of ostracod assemblages to interpret the palaeoenvironments established during Holocene period. Ostracod assemblages were found to be infrequent and of limited diversity in the sediment profile, implying a period of wetter conditions. The highest abundance and more diverse ostracod assemblage were found to be associated with periods of drier climatic condition in the Lake Chamo records. To summarize, the geophysical, geochemical, charcoal, and ostracod data analysis, alongside core chronology results of this thesis have been used to reconstruct Holocene climatic and environmental history of Lake Chamo region, and of the East Africa region as a whole. The main results of this study provide significant input for the understanding of climate variability in the Holocene, as well as identifying termination of the African human period was gradual in Lake Chamo region. IRTG Project Z3 Late Quaternary climate variability in the source region of Homo sapiens: Dry-wet cycles in Chew Bahir, southern Ethiopia 2017-06-26T12:56:22+02:00 Climate change, as a key topic in our society, has far reaching implications for many aspects of our lives, in the past present and evermore in the future. Climatic variability and a rapidly changing environment are considered to have had a significant influence on human evolution, migration and cultural and technological innovation. However, to evaluate the impact that climatic shifts on different timescales might have had on the living conditions of prehistoric humans, an understanding and continuous reconstruction of these climatic fluctuations and their underlying driving mechanisms are essential. This work presents results from such a high resolution (up to 3 years) lake-sediment record from the palaeolake Chew Bahir, a newly invested climate archive in a tectonic-bound basin in southern Ethiopia. The record was obtained from six 9–18.8 long cores along a 17 km NW-SE transect across the basin, today an extensive saline mudflat. The objective of this work is to understand and reconstruct the sensitive patterns and expressions of East Africa‘s highly variable climate, as the climatic context for important cultural transitions in the source region of Homo sapiens. Now, the multi-proxy analyses and interpretation being the heart piece of this thesis, provide the climatic history of the past ~60 ka cal BP and show that Chew Bahir responded sensitively with pronounced shifts in moisture availability towards climatic fluctuations on millennial to centennial timescales, and to the precessional cycle. The first part of this work concentrates on a) the reconstruction of the velocity and character of these late-Quaternary wet-dry transitions on different time scales (orbital, millennial–centennial and decadal) and b) a basic proxy concept for Chew Bahir for the last two insolation controlled wet-dry cycles. This concept comprises be- sides the deciphering of major intra-basin dynamics and mechanisms controlling the way from source to sink, an initial understanding of site-specific proxies: especially potassium as a sensitive indicator for aridity and chlorine as a humidity proxy. The records are based on a set of geochemical, physical and biological indicators as well as a suite of AMS radiocarbon dates. The Chew Bahir cores document a highly non-linear response to the last insolation controlled dry-wet cycle, the so-called African Humid Period (~15–5 ka BP) with a pronounced abrupt onset of humid conditions within <500 yrs and a disproportionally gradual decline of moisture availability, as compared to the decrease in insolation. Feedback mechanisms and a complex interrelationship with the monsoon circulation and the diverse topography of the East African Rift have been suggested as possible key factors. The AHP frames a sharply defined arid phase, corresponding to the Younger Dryas chronozone (~12.8–11.6 ka BP). During the overall arid phase of MIS 3, several oscillations to wetter conditions have been recorded, that resemble the high latitude Dansgaard-Oeschger cycles. Heinrich-events are suggested to be expressed in several episodes of extreme aridity. The full humid conditions of the Holocene wet period [AHP], are punctuated by several abrupt droughts on a centennial to millennial time-scale, the termination of the AHP is though gradual, a textbook example for climatic instability during a transition. A series of 20–80 yr long droughts modulate the 1,500 yr long shift from full wet to arid conditions. In a broader spatio-temporal context this Mid Holocene wet-dry transition in Chew Bahir is evaluated together with two other examples of a change from stable to unstable environmental conditions: the MIS 5–4 transition in the Naivasha basin (central Kenya rift) and thirdly, the Mid Pleistocene Transition in the Olorgesaille basin (Southern Kenya Rift). The concept of hominin speciation, dispersal and cultural innovation being possibly influenced by this transition from stable to unstable environmental conditions is tested on the three different timescales provided by the three records. As a contribution towards a better understanding of human-climate interaction, we compared the last 20 ka of the paleo-climate record from Chew Bahir with the settlement history of adjacent possible refugia in the Ethiopian highlands and around lake margins. Shifts in and out of favourable living conditions are deducted from the climatic history, which shows besides orbitally driven longterm transitions several short abrupt climate events. These are expressed as shifts to pronounced aridity, suggesting phases of climatic stress. Comparing the frequency of archaeological findings as a parameter for human occupation in refugia to this close-by climate record, allows us to outline how complex the interplay between humans and environment during the last 20 ka really was. The results comprised in this work represent an important prerequisite for the ICDP “Hominid Sites and Paleolakes Drilling Project” and for the CRC-806 programme “Our Way to Europe”, which aim to determine climatic and environmental context of human evolution and dispersal. The potential of this deep terrestrial climate archive has been evaluated herein and proved that the sediment deposits are suitable to provide a longer climate history, to be precise to cover with a 400 m core the climatic history of >500,000 yrs in the source region of modern humans. IRTG Project Z3