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Abstract: This paper summarises the results of tephrochronological investigations into a suite of central and southern European records, which include: Rotmeer, southern Germany; Soppensee and Rotsee, central Swiss Plateau; Lago di Lavarone and Lago Piccolo di Avigliana, Italian southern Alpine foreland. These sites provide records of palaeoenvironmental changes for the Last Glacial to Interglacial Transition (LGIT) at the boundary between North Atlantic and Mediterranean climatic influences. Chemical characterisation of glass shards in volcanic ash layers indicates that multiple volcanic sources have contributed to the central European tephra record. Amongst other volcanic markers, the Laacher See Tephra, originating from the Eifel region of Germany c. 12.9 ± 0.1 ka, and the Vedde Ash from Iceland c. 12.1 ± 0.1 ka, are found co-located within the sediments of Rotmeer, Soppensee, Rotsee and Lago Piccolo di Avigliana. These key horizons, which bracket the onset of the Younger Dryas stadial, provide precise calendrically-dated tie points around which a detailed picture of the timing of local and regional environmental transitions can be constructed. Using the co-located tephra layers the re-colonisation of Northern Italian catchment areas by Quercus is shown to occur just prior to the deposition of the Laacher See Tephra layer, whereas to the North of the Alps Quercus and other thermophilous trees do not reappear until several centuries after the deposition of the Vedde Ash. Furthermore, the discovery of the Vedde Ash in Lago Piccolo di Avigliana and Lago di Lavarone is indicative of atmospheric transport of polar air into southern Europe during the Younger Dryas stadial, matching evidence proposed for such transport of polar air during the Last Glacial Maximum (LGM). [Copyright &y& Elsevier]

Abstract: The Vedde Ash is the most important volcanic event marker layer for the correlation of Late Quaternary palaeoenvironmental archives in Europe and the North Atlantic. First defined from its type site localities near Ålesund, Western Norway, the Vedde Ash has now been traced across much of northern and central Europe, into northwest Russia, within North Atlantic marine sediments and into the Greenland ice cores. The Vedde Ash is thought to derive from an eruption of the Katla volcano in Iceland that occurred midway through the Younger Dryas/Greenland Stadial 1 (GS-1), ∼12.1ka BP. Visible and cryptotephra deposits of the Vedde Ash have been found in numerous stratified sites with robust chronologies, which allow its age to be constrained and its dispersal to be mapped. The eruption must have been highly explosive, however few proximal outcrops have been confirmed and this crucial ash layer remains almost exclusively distally-described and characterised using major element glass compositions. The widespread distribution, stratigraphic associations and consistent major element glass chemistry have led the Quaternary tephrochronological community to see the Vedde Ash as a robust and unique chronological marker layer for the Last Glacial to Interglacial Transition (∼10–18ka BP). Here we present new glass analyses of the Vedde Ash from multiple sites around the dispersal area, using a full suite of compositional analysis, including for the first time, single-grain trace element data. These data demonstrate the strong compositional coherence of Vedde Ash deposits. However, comparison with major, minor, and trace element compositional data from several other distally-described Icelandic tephras reveals that both before and after the Younger Dryas chronozone, there were eruptions that generated widespread tephra layers that have comparable glass shard compositions to the Vedde Ash. This implies that these numerous events not only hail from the same volcanic system, but that the melts share similar crystallisation trends and mixing patterns prior to eruption. It seems therefore that composition alone is insufficient for the correlation of some widespread tephra layers: good stratigraphic information and/or robust dating control are also essential. [Copyright &y& Elsevier]

Abstract: The tephrostratigraphy of Soppensee, Switzerland, is presented here for the first time, with new geochemical data for four tephra layers, derived from three volcanic centres. The best available age estimates for the Laacher See Tephra and Vedde Ash layers are incorporated into a revision of the radiocarbon-based Bayesian age-model for the last glacial to interglacial transition at Soppensee, which is used to explore synchronicity of climatic events between Europe and the North Atlantic. Local temperature changes, recorded by biotic and abiotic proxies in Soppensee, appear to shift in phase with the oxygen isotope signal in Greenland at the onset of the Younger Dryas; however with the clarity of improved precision, an apparent offset that likely results from a dating artefact, is seen between records at the termination of the stadial event. From a methodological standpoint, the results clearly show that only by establishing detailed and independent chronological frameworks can abrupt climatic variability be compared between different regions with sufficiently high temporal precision to addresses the notion of hemispheric climatic synchronicity at the centennial scale in the Late Quaternary. Continuing to develop such approaches is therefore essential in order to understand how far in time and space the climate has behaved in such a way. [Copyright &y& Elsevier]

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: This paper focuses on the chronology and environmental significance of a sediment sequence from an alluvial locality in the vicinity of the historic site of Dunadd, Scotland. It outlines the rationale and statistical validity of an age model derived for a sequence of floodplain sediments from which detailed pollen-stratigraphical and plant macrofossil records have been derived. A series of radiocarbon dates are calibrated using a Bayesian modelling approach, the results of which can be refined by incorporating two independent age estimates based on tephra layers of known age. Analysis of the entire floodplain sequence for volcanic glass shards revealed the presence of discrete but geochemically very similar tephra layers within the upper (late Holocene) part of the sequence. Comparison with published geochemical data obtained from Icelandic tephras of historical age indicates strong statistical correlations with the Hekla 1947 AD and Hekla 1510 AD. While the Hekla 1510 AD tephra has previously been reported from sites within Britain and Ireland, the Dunadd sequence affords the first record of the Hekla 1947 AD tephra layer within Scotland. When the ages and stratigraphic positions of both tephra layers are incorporated into the Bayesian age model, an overall centennial to decadal precision for the late Holocene is achieved, with archaeological and environmental transitions discriminated with highest-likelihood age uncertainty ranges of 20–50 years at 95% confidence. The local environmental record is assessed in the light of this new chronological framework: the data support previously reported proposals for two periods of significant climatic deterioration with increased wetness, the first during the early Medieval period and the second during the late 16th and 17th centuries AD. [Copyright &y& Elsevier]

Abstract: Accurate and precise dating is vital to our understanding of the Middle to Upper Paleolithic transition. There are, however, a number of uncertainties in the chronologies currently available for this period. We attempt to examine these uncertainties by utilizing a number of recent developments in the field. These include: the precise dating of the Campanian Ignimbrite (CI) tephra by 40Ar/39Ar; the tracing of this tephra to a number of deposits that are radiocarbon dated; the publication of revised radiocarbon calibration data for the period, showing a much better convergence with other available data than during the recent IntCal comparison; and a layer-counted ice-core chronology extending beyond 40,000cal BP. Our data comparisons suggest that a reasonable overall convergence between calibrated radiocarbon ages and calendar dates is possible using the new curves. Additionally, we suggest that charcoal-based radiocarbon ages, as well as bone-based radiocarbon determinations, require cautious interpretation in this period. Potentially, these issues extend far beyond the sites in this study and should be of serious concern to archaeologists studying the Middle to Upper Paleolithic. We conclude by outlining a strategy for moving the science forward by a closer integration of archaeology, chronology, and stratigraphy. [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: A new Icelandic ash layer has been detected in mid-Interstadial sediments in a number of Scottish Lateglacial sequences and has been named the Penifiler Tephra. It is rhyolitic in composition and possesses a chemistry, which is similar to the Borrobol Tephra of early Lateglacial Interstadial age, which also occurs in a number of these same sequences. Where the Borrobol Tephra has been identified in these sequences it consistently exhibits a diffuse distribution accompanied in some cases by stratigraphic bimodality. A number of sedimentological and taphonomic factors are considered in order to account for this distribution. One possibility is that these distributions are produced by taphonomic factors. Another possibility is that the Borrobol Tephra may not be the product of a single Icelandic eruption, but of two events closely spaced in time. In at least two of the sequences investigated in this study, basaltic shards were found in association with the Penifiler and Borrobol tephras, suggesting either a basaltic phase associated with these eruptions, or coincident eruptions from a separate basaltic volcanic centre. The discovery of the new Penifiler Tephra makes a contribution to the regional tephrostratigraphic framework, and provides an additional isochron for assessing the synchroneity of palaeoenvironmental changes during the Interstadial. The true stratigraphic nature and age of the Borrobol Tephra, however, remains unresolved and, therefore, its use as an isochron is more problematic. The possible occurrence of basaltic populations may strengthen correlations with basaltic tephras recently detected in the NGRIP ice-core. [Copyright &y& Elsevier]

Abstract: As part of ongoing research to find distal tephra, two lacustrine cores were analysed for the presence of volcanic ash layers, not visible to the naked eye: Soppensee, in Switzerland, and Rotmeer, in Southern Germany. The Laacher See Tephra (∼12,900kaBP) is present as a visible layer in both sites. In both cores we found a discrete tephra horizon, with similar morphologies, in the middle of the biostratigraphic units equivalent to the Younger Dryas stadial. The vitreous components of these two tephra layers are geochemically identical. Comparison of the geochemical, stratigraphical, and chronological data from both sites, strongly suggest that the tephra can be attributed to the Icelandic Vedde Ash, a widely distributed horizon found throughout the North Atlantic and Northern Europe. Our results indicate that a precise and direct correlation between the Greenland ice cores and Central European sequences is now possible, based on a co-located tephra layer. This means that there is now the potential, to independently test climate synchronicity between Greenland and Europe, as far south as the Alps. [Copyright &y& Elsevier]

Abstract: The growing importance of understanding past abrupt climate variability at a regional and global scale has led to the realisation that independent chronologies of past environmental change need to be compared between various archives. This has in turn led to attempts at significant improvements in the required precision at which records can be dated. Radiocarbon dating is still the most prominent method for dating organic material from terrestrial and marine archives, and as such many of the recent developments in improving precision have been aimed at this technique. These include: (1) selection of the most suitable datable fractions within a record, (2) the development of better calibration curves, and (3) more precise age modelling techniques. While much attention has been focussed on the first two items, testing the possibilities of the relatively new age modelling approaches has not received much attention. Here, we test the potential for methods designed to significantly improve precision in radiocarbon-based age models, wiggle match dating and various forms of Bayesian analyses. We demonstrate that while all of the methods can perform very well, in some scenarios, caution must be taken when applying them. It appears that an integrated approach is required in real life dating situations where more than one model is applied, with strict error calculation, and with the integration of radiocarbon data with sedimentological analyses of site formation processes. [Copyright &y& Elsevier]

Abstract: The use of Late Quaternary tephra horizons as isochronous markers for high resolution correlation between records is of growing importance in a number of scientific fields. Particular advancements have been made through the identification of microtephra deposits (very distal deposits of volcanic ash invisible to the naked eye). The successful correlation of ash layers and volcanic eruptions depends on the acquisition of the major element chemistries of a tephra layer, derived from microprobe analyses of individual glass shards. This is particularly important for microtephras where aeolian fractionation has removed much of the mineral phase of the ash deposit, which often aids tephra discrimination. There are, however, difficulties in distinguishing precisely between different eruptions of the same volcano using major element composition and this may not always be resolved by the use of trace elements. Given the potential of tephrochronology as a correlative tool in many disciplines it is important to resolve this difficulty. One way forward is to perform more robust statistical analyses on the geochemical data, as in general, analyses are confined to a series of bi-plots of major elements. Here the authors explore some of the problems associated with dealing with microprobe data generated for individual tephras and pay particular attention to the ‘unit sum problem’. Using a subset of data generated as part of a EURODELTA project on tephra distribution in the Adriatic, the authors demonstrate that this problem is detectable in major element data from tephras and have consequently applied the logratio method before further analyses of the data. It is demonstrated that the use of logratios combined with discriminant functions analysis provides a more robust assessment of likely chemical correlations between tephras, and are superior to the use of bi-plots alone; and obviate the need for any data normalization, a particular point of contention between tephrochronologists. [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: Tephrochronology, a key tool in the correlation of Quaternary sequences, relies on the extraction of tephra shards from sediments for visual identification and high-precision geochemical comparison. A prerequisite for the reliable correlation of tephra layers is that the geochemical composition of glass shards remains unaltered by natural processes (e.g. chemical exchange in the sedimentary environment) and/or by laboratory analytical procedures. However, natural glasses, particularly when in the form of small shards with a high surface to volume ratio, are prone to chemical alteration in both acidic and basic environments. Current techniques for the extraction of distal tephra from sediments involve the ‘cleaning’ of samples in precisely such environments and at elevated temperatures. The acid phase of the ‘cleaning’ process risks alteration of the geochemical signature of the shards, while the basic phase leads to considerable sample loss through dissolution of the silica network. Here, we illustrate the degree of alteration and loss to which distal tephras may be prone, and introduce a less destructive procedure for their extraction. This method is based on stepped heavy liquid flotation and which results in samples of sufficient quality for analysis while preserving their geochemical integrity. In trials, this method out-performed chemical extraction procedures in terms of the number of shards recovered and has resulted in the detection of new tephra layers with low shard concentrations. The implications of this study are highly significant because (i) the current database of distal tephra records and their corresponding geochemical signatures may require refinement and (ii) the record of distal tephras may be incomplete due to sample loss induced by corrosive laboratory procedures. It is therefore vital that less corrosive laboratory procedures are developed to make the detection and classification of distal glass tephra more secure. [Copyright &y& Elsevier]

Tephra layers are assuming an increasingly important role in the dating and correlation of Late Quaternary marine sequences. Here we demonstrate their potential by reporting a new study of the sediment sequence of marine core SA03-11, recovered from the Southern Adriatic Sea, which spans the last c. 39 ka. A total of 28 discrete tephra layers are reported from this sequence, 10 of which are visible in the core and a further 18 are non-visible cryptotephra layers. These have been analysed using more than 1400 WDS-EPMA measurements of glass chemistry and results have been compared with published chemical measurements obtained from relevant proximal and distal sites which preserve eruptive material dating to within the same time interval. The data show that a high proportion of the layers originate from the Campi Flegrei volcanic field but more distinctive layers are sourced from Vesuvius, the Aeolian Islands and Vulcano, and these provide key marker horizons. The results show that the sequence extends in time to the Campanian Ignimbrite at the base, that a number of the layers have robust age estimates that permit a better constrained age–depth model to be constructed for the sequence, and that the potential exists for importing terrestrially-based age estimates into marine contexts, thereby circumventing problems of incorporating reservoir uncertainties associated with marine radiocarbon dates. The WDS-EPMA dataset generated here also provides important new data that constrain key Late Quaternary tephra layers in the central Mediterranean region. [ABSTRACT FROM AUTHOR]

Tephra layers preserved in marine sediments can contribute to the reconstruction of volcanic histories and potentially act as stratigraphic isochrons to link together environmental records. Recent developments in the detection of volcanic ash (tephra) at levels where none is macroscopically visible (so-called ‘crypto-tephra’) have greatly enhanced the potential of tephrostratigraphy for synchronising environmental and archaeological records by expanding the areas over which tephras are found. In this paper, crypto-tephra extraction techniques allow the recovery of 8 non-visible tephra layers to add to the 9 visible layers in a marine sediment core (LC21) from the SE Aegean Sea to form the longest, single core record of volcanic activity in the Aegean Sea. Using a novel, shard-specific methodology, sources of the tephra shards are identified on the basis of their major and trace element single-shard geochemistry, by comparison with geochemical data from proximal Mediterranean volcanic stratigraphies. The results indicate that the tephra layers are derived from 14 or 15 separate eruptions in the last ca 161 ka BP: 9 from Santorini; 2 or 3 from Kos, Yali, or Nisyros; 2 from the Campanian province; and one from Pantelleria. The attributions of these tephra layers indicate that 1) inter-Plinian eruptions from Santorini may have produced regionally significant tephra deposits, 2) marine tephrostratigraphies can provide unique and invaluable data to eruptive histories for island volcanoes, and 3) tephra from both Pantelleria and Campania may be used to correlate marine records from the Aegean Sea to those from the Tyrrhenian, Adriatic and Ionian Seas. [ABSTRACT FROM AUTHOR]

Core PRAD 1-2, located on the western flank of the Mid-Adriatic Deep, was investigated for tephra content within the part of the sequence assigned on biostratigraphic and sapropel-layer stratigraphy to MIS 5 and 6 (ca. 80–200 ka BP). A total of 11 discrete tephra layers are identified, 8 visible and 3 cryptotephra layers. 235 geochemical measurements obtained from individual glass shards using WDS-EPMA enabled 8 of the 11 tephras to be correlated to known eruption events, 5 of which are represented in the Lago Grande di Monticchio (LGdM) regional tephra archive sequence. Three of these layers are recognised ultra-distally for the first time, extending their known distributions approximately 210 km further north. The results provide an independent basis for establishing an age-depth profile for the MIS 5–6 interval in the PRAD 1-2 marine record. This approach allowed age estimates to be interpolated for the tephra layers that could not be correlated to known events. It also provides an independent test of, and support for, the broad synchroneity of sapropel-equivalent (S-E) events in the Adriatic Sea with the better-developed sapropel layers of the eastern Mediterranean, proposed by Piva et al. (2008a). [ABSTRACT FROM AUTHOR]

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]

Abstract: Core PRAD 1-2, located on the western flank of the Mid-Adriatic Deep, contains a continuous sediment record extending back to upper MIS-11. The upper part of the record which spans the mid Holocene to MIS 5–4 (the last ca 105,000 years) has been investigated for tephra content. A total of 25 discrete tephra layers were discovered, only one of which was visible in the core sequence. The other 24 are not visible to the naked eye, nor were the majority detected by routine down-core scanning methods. A total of 625 geochemical measurements obtained from individual glass shards using WDS-EPMA enabled 21 of the 25 tephras to be assigned to known volcanic events emanating from the Campanian Province (Campi Flegrei, Somma-Vesuvius and Ischia Island). The results provide an independent basis for establishing an age–depth profile for the upper part of the PRAD 1-2 record. This study demonstrates that the number of non-visible tephra layers can significantly exceed the number of visible layers in some deep marine sequences. Routine testing for the presence of non-visible tephra layers can therefore prove rewarding, leading to the detection of additional isochrons for dating and correlating marine sequences, and for their synchronisation with terrestrial records. [ABSTRACT FROM AUTHOR]

A multi-proxy environmental record for the Devensian (Weichselian) Lateglacial and early Holocene periods, which includes pollen, plant macrofossil, coleopteran, geochemical and stable-isotope data, is described from a site at Llanilid, South Wales, UK. The geochronology of the sequence is derived from two age–depth models which show a broad measure of agreement over much of the profile. This data set provides the basis for a detailed reconstruction of changing environmental conditions in western Britain during the transition from the Last Cold Stage to the present (Holocene) interglacial (ca 15,000–10,000 cal yr BP). Two marked cooling episodes are recorded during the course of the Lateglacial Interstadial (Greenland Interstadial 1), with mean July temperatures falling by more than 5°C from a maximum of around 20°C during the early Interstadial, and by a further 4–5°C around 13,100 cal yr BP. The initial drop in temperature led to a reduction in Juniperus scrub, while the second, and more abrupt temperature decline resulted in a significant contraction in areas of Betula woodland. A relatively slight and short-lived warming during the later Interstadial enabled tree birch to expand once again. Mean July temperatures of 10–11°C characterised the Loch Lomond/Younger Dryas Stadial (Greenland Stadial 1) between ca 12,600 and 11,400 cal yr BP, during which time a scrub tundra with Betula, Salix and a range of open-habitat taxa became established locally. The onset of the Holocene Interglacial at ca 11,400 cal yr BP is marked by an abrupt temperature rise of the order of 9°C, and by the rapid expansion of Betula woodland. The Llanilid palaeoclimate record is similar to that from the Gransmoor site in northeast England, and also to the climatic sequence inferred from the GRIP ice core, particularly during the later part of the Lateglacial Interstadial (ca 14,000–12,600 cal yr BP), during the Loch Lomond/Younger Dryas Stadial and in the early Holocene. The Llanilid chronology is less secure during the early part of the Lateglacial Interstadial (pre-14,000 cal yr BP), but it is possible that warming may have begun earlier in this part of western Britain than in Greenland. [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]