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Abstract: This paper re-examines the chronology and environmental context for the transition to agriculture in the Southern Levant, seen as the likely starting point for the adoption of agriculture in Europe and the Near East. The role in this process of abrupt late Quaternary climate change has been discussed widely, but limitations on the archaeological and palaeoenvironmental chronologies have led to varying interpretations. Here we attempt to clarify the situation by first testing the available radiocarbon database for the archaeological transitions from the Natufian through to the PPNA. We apply internationally accepted radiocarbon quality assurance procedures and find that a significant number of the published dates fall bellow acceptable standards. The cleaning process significantly clarifies and constrains the reported time ranges for the Natufian, Late Natufian and PPNA. We then apply the new IntCal09 calibration curve and Bayesian calibration methods, using the archaeological phasing to constrain the data and calculate the most likely timing of the transitions between each phase. We then compare the onset and duration of archaeological phases to data representing the key Northern Hemisphere climatic transitions, using the new GICC05 Greenland Ice core timescale and the timing of transitions between wet and dry phases in the southern Levant from published high precision isotopic analyses of Speleothem data. The results of this exercise present the currently best available chronology for these events and suggest that during the second part of the Lateglacial interstadial, drying of the southern Levant may have triggered the transition to the Late Natufian, when hunter-gatherer communities resorted to a more mobile lifestyle. The Late Natufian culture appears to have disappeared from the southern Levant during the Younger Dryas, as drying intensified. There is then a gap in well dated evidence for human occupation until a reappearance of humans at the onset of the Pre-Pottery Neolithic A (PPNA) period at the beginning of the Holocene. Thus the onset of the Holocene can be hypothesised to be the driver behind the onset of the Neolithic in this region. [Copyright &y& Elsevier]

Abstract: One of the key factors in understanding past climate change is the development of robust age models that have sufficient chronological precision for comparing different palaeoclimate archives, while retaining accuracy. Recent developments in Bayesian age modelling are applied here to the Swiss varve lake, Soppensee. We develop revised age models for this sequence using the available stratigraphic information to constrain the calibrated radiocarbon ages. We begin by using stratigraphical order as the only constraint and then sequentially increase the information incorporated into the model, using relative varve age, sample depth, and varying depositional models. Within this Bayesian framework, we develop internally robust models that significantly improve the dating precision and are applicable to both varved and non-varved sequences. We then compare the model output to wider chronological information, such as the age of the Laacher See Tephra in order to test the model accuracy. The results of this exercise suggest that these methods can be used to build very reliable improved age models in a variety of records. [Copyright &y& Elsevier]

Abstract: The Mutual Climatic Range (MCR) method, originally developed in the early 1980s to derive quantified palaeotemperature estimates from fossil beetle assemblage data, is based on assessments of the relationships between the modern distributions of beetle species and instrumentally measured climatic gradients. However, the MCR approach is based on presence/absence beetle data only, with no information on the spatial variation in relative dominance/importance of beetle species within their present climate ranges. This means that beetle–climate relationships are more difficult to test using conventional, probabilistic statistical methods. It is also unlikely that beetles have a normal (Gaussian) distribution in climate space, and hence calibration methods developed for correcting MCR values for bias in raw data are also questionable. In this paper, the underlying statistical weaknesses in the MCR method are examined, while an alternative approach, Ubiquity Analysis, is introduced. It is concluded that this approach offers much potential for reducing the uncertainties associated with MCR estimates. [Copyright &y& Elsevier]

Abstract: At the millennial scale bog surface wetness (BSW) records show a clear Holocene climate event stratigraphy, with major phases comparable with other regional climate proxies such as chironomid inferred temperature records. Moving towards the centennial scale, however, and towards the limits of chronological certainty within the records, regional differences are apparent which likely reflect the more heterogeneous precipitation patterns which occur on shorter timescales. The BSW data presented in this paper are reconstructed from testate amoebae assemblages from central Ireland and are compared with other regional records. The results suggest that this region is in phase with the North of Ireland in terms of timings and durations of climate change, but the comparisons are less clear with a stacked and tuned record from Northern Britain that shows an apparent offset compared to the Irish records. This may reflect variations in past regional precipitation or be a function of the tuning and stacking process. The broad phases of comparison between the Irish records, and the extension of the central Irish record back to 6000 cal BP, allow comparisons with low frequency temperature reconstructions from chironomids, which also show a broad level of correlation, with cooler temperatures relating to wetter BSW at centennial to millennial timescales. [Copyright &y& Elsevier]

The Southern Caucasus lies at the intersection of Africa, the Levant and Eurasia, and is thus a region of considerable interest in the study of Pleistocene hominin population dynamics and behaviour. While Palaeolithic archaeological sites in the region such as Dmanisi and Nor Geghi 1 attest to such palaeogeographic significance, a greater understanding of the chronology and nature of climatic and geomorphic changes in the region is needed to fully understand hominin settlement dynamics. The Hrazdan river valley, central Armenia, has the potential to offer such insights given its rich Palaeolithic record and complex history of Pleistocene infill as a result of alluvial, lacustrine, aeolian, and volcanic processes. We therefore present a stratigraphic framework for basin infill and hominin activity during the Pleistocene, based on extensive geomorphological and geological mapping, published chronometric results (40Ar/39Ar and K-Ar), and archaeological survey. We demonstrate that the onset of Pleistocene volcanism in the Gegham Range to the immediate east of the Hrazdan valley occurred around 700 ka BP, after which there were several phases of effusive eruption lasting until 200 ka. Interbedded with lava emplaced by these eruptions are alluvial and lacustrine sequences, some with evidence of pedogenesis and several of which have yielded Palaeolithic artefacts. Taken together these sequences suggest a cyclical model of infill whereby lava flow along the valley resulted in the blockage of the palaeo-Hrazdan river and lake formation in the lea of the lava dams. Breaching of these dams resulted in a shift to predominately fluvial deposition, and the consequent development of floodplain soils. Hominin populations exploited the floodplains at times when the last of these phases coincided with interglacial and interstadial climates, but they also occupied the surrounding valley sides during the same warm, humid phases. • Development of a stratigraphic framework for volcanism, landscape development and Palaeolithic occupation in the Central Armenian Highlands. • Demonstrates several phases of effusive and explosive volcanic activity during the Middle and Late Pleistocene. • Landscape change was caused by a combination of volcanic activity, hydrological development and climate change. • Preservation of stratified Palaeolithic sequences indicates that hominins were exploiting floodplain and lake environments during warm episodes. • Close association of sedimentarysequences and volcanic products provides a rare opportunity for precisely dating Palaeolithic occupations. [ABSTRACT FROM AUTHOR]