Search

In the Pacific region, the onset of modern El Nino/Southern Oscillation (ENSO) activity at approximately 5000 years ago may have played a significant role in the development of cultures in the Pacific basin. Within Australia, similar trends in population and resource use have been identified but largely ascribed to cultural changes. To test human responses to changing ENSO activity through the Holocene we analysed a comprehensive suite of 710 radiocarbon ages from archaeological sites in ENSO-sensitive Queensland. We observe a dramatic and sustained increase in landscape activity at inland sites from 4860 ± 15 years ago, statistically indistinguishable from the timing of the onset of modern ENSO activity. Subsequent changes in long-term activity directly impacted on human populations indicating that once established, ENSO maintained a continuous influence on disparate cultures throughout the Pacific basin.

It is critical that a comprehensive terrestrial radiocarbon (C-14) calibration curve is developed beyond 26 ka for high-precision calibration and correlation of climatic, environmental and archaeological records. Abundant sub-fossil New Zealand kauri (Agathis australis) wood, preserved in Oxygen Isotope Stage-2 and 3 peat swamps, provides an important resource for C-14 calibration; nowhere else in the world does such an extensive collection of ancient wood exist. Although finite C-14 ages beyond 50 ka are becoming routinely reported, few attempts have been made to demonstrate their accuracy or precision. Finite ages beyond 50 ka require optimization of all elements involved in sample preparation and C-14 analysis. Here we discuss the methodology employed for optimizing the C-14 dating of near-background wood samples by both benzene synthesis for liquid scintillation counting (LSC) or graphite synthesis for accelerator mass spectrometry (AMS). We report the mean background blank activities for both methods and present a statistical model for assigning blank standard errors when blank activity variation is over and above counting statistics. We also present duplicate analyses (using LSC and AMS) of nine successive samples of wood obtained from a sub-fossil kauri log near-background in age to investigate the significance of the measured blank levels and variability. (c) 2006 Elsevier Ltd. All rights reserved.

There are many geochemical reconstructions of environmental change in the mid and high latitudes but relatively few in the tropical latitudes, despite their considerable potential for reconstructing environmental processes that cannot be identified using more traditional proxies. Here we present one reconstruction of environmental change for the tropics. This reconstruction covers the past 50 ka using a suite of geochemical data from the high-resolution sequence of Lynch's Crater in northeast Queensland, Australia, a region highly sensitive to El Nino-Southern Oscillation (ENSO) activity. The 23 major oxides and trace elements measured Could be summarised by extracting three axes using principal components analysis (accounting for 72% of the variability). The data indicate that the greatest variability in the geochemical data accounted for erosional activity within the catchment that was associated with past changes in the frequency of ENSO activity (though this was less sensitive during wetter periods, probably as a result of buffering by high vegetation cover). The remaining variability was largely explained by elements that form complexes with organic compounds (e.g., humic acids) and those that are important nutrients for specific vegetation types (and therefore a measure of vegetation distribution). For more detailed reconstructions, further work is required to disentangle the complex controls of clements within sedimentary sequences. (c) 2005 Elsevier B.V. All rights reserved.

A significant uncertainty exists as to whether δ13C values in charcoal meaningfully represent the stable isotopic content of the original material, with studies suggesting variable responses to both natural and laboratory heating. An extensive study was undertaken using fully homogenised samples of wood taken from Eucalyptus spp., Quercus robur and Pinus radiata. The results demonstrate that the duration of heating had no tangible effect on the final composition of the charred material, with the δ13C and carbon content of wood fixed after 30 min of heating. Furthermore, all three wood types become progressively depleted in 13C with increasing temperature. The results demonstrate that even at temperatures commonly reached in natural fires (

The extent to which North Atlantic Holocene climatic perturbations influenced past human societies is an area of considerable uncertainty and fierce debate. Ireland is ideally placed to help resolve this issue, being occupied for over 9000 yr and located on the eastern Atlantic seaboard, a region dominated by westerly airflow. Irish bog and lake tree populations provide unambiguous evidence of major shifts in surface moisture through the Holocene similar to cycles recorded in the marine realm of the North Atlantic, indicating significant changes in the latitude and intensity of zonal atmospheric circulation across the region. To test for human response to these cycles we summed the probabilities of 465 radiocarbon ages obtained from Irish archaeological contexts and observe enhanced archaeological visibility during periods of sustained wet conditions. These results suggest either increasing density of human populations in key, often defensive locations, and/or the development of subsistence strategies to overcome changing conditions, the latter recently proposed as a significant factor in avoiding societal collapse. Regardless, we demonstrate environmental change is a significantly more important factor in influencing human activity in the landscape than has hitherto been acknowledged.

The Northern Hemisphere cooling event 8200 years ago is believed to represent the last known major freshwater pulse into the North Atlantic as a result of the final collapse of the North American Laurentide ice sheet. This pulse of water is generally believed to have occurred indepen- dently of orbital variations and provides an analogue for predicted increases in high-latitude preci- pitation and ice melt as a result of anthropogenically driven future climate change. The precise timing, duration and magnitude of this event, however, are uncertain, with suggestions that the 100-yr melt- water cooling formed part of a longer-term cold period in the early Holocene. Here we undertook a multiproxy, high-resolution investigation of a peat sequence at Dooagh, Achill Island, on the west coast of Ireland, to determine whether the 8200-year cold event impacted upon the terrestrial vege- tation immediately 'downwind' of the proposed changes in the North Atlantic. We find clear evidence for an oscillation in the early Holocene using various measures of pollen, indicating a disruption in the vegetation leading to a grassland-dominated landscape, most probably driven by changes in precipitation rather than temperature. Radiocarbon dating was extremely problematic, however, with bulk peat samples systematically too young for the North Atlantic event, suggesting significant contamination from downward root penetration. The sustained disruption to vegetation over hundreds of years at Dooagh indicates the landscape was impacted by a long-term cooling event in the early Holocene, and not the single century length 8200-year meltwater event proposed in many other records in the North Atlantic region. Copyright 2006 John Wiley & Sons, Ltd.

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.

The temporal and spatial extent of Holocene climate change is an area of considerable uncertainty, with solar forcing recently proposed to be the origin of cycles identified in the North Atlantic region. To address these issues we have developed an annually resolved record of changes in Irish bog tree populations over the last 7468 years which, together with radiocarbon-dated bog and lake-edge populations, extend the dataset back to ∼9000 yr ago. The Irish trees underpin the internationally accepted radiocarbon calibration curve, used to derive a proxy of solar activity, and allow us to test solar forcing of Holocene climate change. Tree populations and age structures provide unambiguous evidence of major shifts in Holocene surface moisture, with a dominant cyclicity of 800 yr, similar to marine cycles in the North Atlantic, indicating significant changes in the latitude and intensity of zonal atmospheric circulation across the region. The cycles, however, are not coherent with changes in solar activity (both being on the same absolute timescale), indicating that Holocene North Atlantic climate variability at the millennial and centennial scale is not driven by a linear response to changes in solar activity. Copyright © 2005 John Wiley & Sons, Ltd.

Lithology, pollen, macrofossils, and stable carbon isotopes from an intermontane basin bog site in southern New Zealand provide a detailed late-glacial and early Holocene vegetation and climate record. Glacial retreat occurred before 17,000 cal yr B.P., and tundra-like grassland"shrubland occupied the basin shortly after. Between 16,500 and 14,600 cal yr B.P., a minor regional expansion of forest patches occurred in response to warming, but the basin remained in shrubland. Forest retreated between 14,600 and 13,600 cal yr B.P., at about the time of the Antarctic Cold Reversal. At 13,600 cal yr B.P., a steady progression from shrubland to tall podocarp forest began as the climate ameliorated. Tall, temperate podocarp trees replaced stress-tolerant shrubs and trees between 12,800 and 11,300 cal yr B.P., indicating sustained warming during the Younger Dryas Chronozone (YDC). Stable isotopes suggest increasing atmospheric humidity from 11,800 to 9300 cal yr B.P. Mild (annual temperatures at least 1°C higher than present), and moist conditions prevailed from 11,000 to 10,350 cal yr B.P. Cooler, more variable conditions followed, and podocarp forest was completely replaced by montane Nothofagus forest at around 7500 cal yr B.P. with the onset of the modern climate regime. The Cass Basin late-glacial climate record closely matches the Antarctic ice core records and is in approximate antiphase with the North Atlantic.

Fieldtrips are a crucial and established component of teaching in the Earth Sciences, providing an effective means of turning theory into practice. Increasing class sizes, ‘exotic’ locations and the associated costs, however, often make it impractical to take the students into the field. In an attempt to reconcile these issues, we have started exploiting technology to develop a new module entitled ‘Volcanoes, Humans and Environmental Catastrophes’ for which five ‘virtual’ field trips were integrated within the University’s Virtual Learning Environment. The fieldtrips were formed around online interactive maps that allowed the students to explore the field study environment by streamlined film footage, high quality images and text. This paper explores the advantages of this approach and identifies problems that are likely to be of relevance to colleagues developing similar resources in their own speciality.

A technique for determining the radiocarbon age of both organic-carbon and carbonate-carbon in the eggshell of the large flightless birds Genyornis newtoni (now extinct) and Dromaius novaehollandiae (extant emu) is presented here. Stepped combustion (for organic-carbon) and stepped acidification (for carbonate-carbon) were used to obtain multiple age determinations for each sample, from which an assessment of the reliability of the ages is possible. Analysis of a Genyornis newtoni eggshell fragment known to have an age considerably beyond the limit of radiocarbon dating has indicated that the backgrounds obtainable using this approach are 0.122±0.033 pMC for the organic-carbon fraction and 0.070±0.025 pMC for the carbonate-carbon fraction. These backgrounds suggest that finite ages up to 50,000–55,000 BP are readily achievable on eggshell using stepped combustion/acidification. Analysis of a single fragment of Genyornis eggshell from Williams Point, central South Australia, suggests that significant contamination of the organic-carbon fraction of the eggshell is possible, while ages for the carbonate fraction appear more reliable and indicate that the eggshell has an age of at least 49,000±2000 BP. A total of six analyses of single Genyornis newtoni and Dromaius novaehollandiae eggshell fragments from the Wood Point deposit in southern South Australia suggest ages for the samples of 41,000±800 and 37,900±700 BP, respectively, while an optically stimulated luminescence (OSL) sample from a location very close to the Genyornis sample has an age of 55±5 ka (1σ). The OSL and calibrated radiocarbon ages for the Genyornis sample and the sand matrix overlap at two standard deviations, suggesting the most likely age for the eggshell and the sand matrix is ∼45 cal ka BP or earlier.

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.

Synopsis Basaltic tephra horizons dominate the Icelandic tephrochronological framework during the last glacial-interglacial transition (LGIT; 15–10 ka cal. bp), providing excellent potential for high precision correlation of palaeoclimate data-sets as recorded in ice, marine and terrestrial sequences of the North Atlantic region. Although significant advances have been made in identifying and extending the known provenance of rhyolitic tephras (in the form of microtephra horizons), the detection of basaltic layers has proved problematic. The bimodal Vedde Ash is an important chronological marker horizon that lies firmly within the GS-1/Younger Dryas chronozone (ca. 10.3 ka 14 C bp; 12.0 ka GRIP ice-core yrs) and provides an excellent opportunity to develop methodologies for extracting both rhyolitic and basaltic ash. The recent identification of the rhyolitic component across Europe using flotation techniques has significantly extended the known provenance of this eruption event. However, there is no routine methodology for the identification of basaltic microtephra horizons and the separation of this component of the Vedde Ash has therefore been limited to visible horizons in Iceland, western Norway and the Isle of Skye. Here, we use magnetic separation techniques to identify for the first time basaltic Vedde Ash as a microtephra horizon in minerogenic sequences from two sites in western Scotland.

The record of deposition of tephras in Europe and the North Atlantic during the period 18.5-8.0 (14)C ka BP (the Last Termination and Early Holocene) is reviewed. Altogether, 34 tephras originating from four main volcanic provinces (Iceland, the Eifel district, the Massif Central and Italy) have been identified so far in geological sequences spanning this time-interval. Most of the records have been based, until very recently, on observations of visible layers of tephras. Here, we report on the potential for extending the areas over which some of the tephras can be traced by the search for layers of micro-tephra, which are not visible to the naked eye, and on the use of geochemical methods to correlate them with known tephra horizons. This approach has greatly extended the area in Northern Europe over which the Vedde Ash can be traced. The same potential exists in southern Europe, which is demonstrated for the first time by the discovery of a distinct layer of micro-tephra of the Neapolitan Yellow Tuff in a site in the Northern Apennines in Italy, far to the north of the occurrences of visible records of this tephra. The paper closes by considering the potential for developing a robust European tephrostratigraphy to underpin the chronology of records of the Last Termination and Early Holocene, thereby promoting a better understanding of the nature, timing and environmental effects of the abrupt climatic changes that characterized this period.

This study presents the results of an extensive radiocarbon dating program at the Nauwalabila I site in northern Australia. The results show that the radiocarbon chronology at Nauwalabila is reliable to ∼130 cm depth, but below this depth coarse charcoal has been variably altered during a period in the early Holocene when an ephemeral groundwater table reached close to the ground surface of the time. Below ∼150 cm none of the radiocarbon ages can be considered to indicate reliably the age of deposition of the sediments. Luminescence dates near the surface and at 110 cm are concordant with the radiocarbon chronology in the upper part of the sequence, and hence the aberrant radiocarbon results below ∼150 cm do not constitute a reason to doubt the accuracy of the luminescence chronology deeper in the stratigraphy. A conservative estimate of the age of the sequence, based on extrapolation of results from that portion of the sequence where the radiocarbon chronology is considered to be reliable, is consistent with the chronology proposed previously from luminescence dating. Both chronologies therefore suggest occupation of the site before 50,000 years. Based on sediment characteristics and the distribution of quartz, chert, quartzite and ‘quartz crystal’ artefacts, there is no evidence that there has been significant vertical displacement of artefacts relative to the surrounding sand matrix. Both chemical alteration and physical translocation of charcoal contributed to the aberrant ages at depth in the deposit. The results point to the need for careful assessment of the suitability of charcoal for radiocarbon dating prior to analysis and to the dangers of relying on a small number of radiocarbon dates in the development robust site chronologies. Strategies for screening samples for suitability include (i) microscopic examination, (ii) not analysing samples unless they survive the full ABOX pretreatment, (iii) not analysing samples unless the material is significantly larger than the sediment matrix, (iv) using CHN analysis on both untreated and pretreated material to check for organic contamination and (v) using stepped combustion to check for concordancy in the ages of carbon released at successively higher temperatures.

Antarctic Science, 26 (6), ISSN:0954-1020, ISSN:1365-2079

Globally, there has been much recent effort to improve understanding of climate change-related shifts in rainfall patterns, variability and extremes. Comparatively little work have focused on how such shifts might be altering hydrological regimes within arid regional basins, where impacts are expected to be most significant. Here, we sought to identify the main hydroclimatic determinants of the strongly episodic flood regime of a large catchment in the semi-arid, subtropical northwest of Australia and to establish the background of hydrologic variability for the region over the last century. We used a monthly sequence of satellite images to quantify surface water expression on the Fortescue Marsh, the largest water feature of inland northwest Australia, from 1988 to 2012. We used this sequence together with instrumental rainfall data to build a multiple linear model and reconstruct monthly history of floods and droughts since 1912. We found that severe and intense regional rainfall events, as well as the sequence of recharge events both within and between years, determine surface water expression on the floodplain (i.e., total rainfall, number of rain days and carried-over inundated area; R2adj = 0.79; p value < 0.001, ERMSP = 56 km2). The most severe inundation (~1000 km2) over the last century was recorded in 2000. The Fortescue Marsh was completely dry for 32% of all years, for periods of up to four consecutive years. Extremely wet years (seven of the 100 years) caused the Marsh to remain inundated for up to 12 months; only 25% of years (9% of all months) had floods of greater than 300 km2. Duration, severity and frequency of inundations between 1999 and 2006 were above average and unprecedented when compared to the last century. While there is high inter-annual variability in the system, changes to the flooding regime over the last 20 years suggest that the wetland will become more persistent in response to increased frequency and intensity of extreme rainfall events for the region, which in turn will likely impact on the structure and functioning of this highly specialized ecosystem.

The degree to which post-depositional disturbance can be assessed in archaeological sequences is critical for the development of robust chronologies for such deposits. A common approach is the identification of conjoined artefacts distributed through the sequence as a measure of disturbance following deposition, although this method is relatively labour intensive and does not provide a continuous record of disturbance through the entire sequence. Here we present δ13C values for different size fractions ( 125 µm) of chemically resistant charcoal distributed through a sedimentary profile at Allen's Cave, South Australia. The curves generated from both size fractions parallel one another, indicating minimal disturbance through the entire profile and providing greater confidence in the luminescence and radiocarbon chronologies reported previously for the site. In addition, the elemental δ13C values provide an indication of greater aridity (compared with present) persisting in this area from ca. 45 to 12 ka, consistent with other proxy records. The onset of the Holocene is marked by a shift to wetter conditions, probably as a result of post-glacial marine transgression and closer proximity to the coastline. Copyright © 2001 John Wiley & Sons, Ltd.

Charcoal samples from ancient human occupation sites in Australia have been subjected to a rigorous pretreatment and stepped combustion regime in order to explore the possibility that these sites may be older than previous radiocarbon dating had suggested. In one case, the Devil's Lair site in southwest Australia, the methodology has clearly removed vestiges of contamination by more modern carbon and has led to a revised radiocarbon chronology that provides evidence for human occupation of southwest Australia by at least 44 ka BP and probably by 46–47 ka BP. In contrast, charcoal from the Nauwalabila site has been so severely altered that insufficient of the original carbon remains for reliable 14C dating. Finally, where the charcoal is well preserved, such as at the Carpenter's Gap site, the new results provide reassurance that earlier 14C results of ∼40 ka BP are indeed true ages and are not simply at the limit of the 14C technique.

New dating confirms that people occupied the Australian continent before the earliest time inferred from conventional radiocarbon analysis. Many of the new ages were obtained by accelerator mass spectrometry 14C dating after an acid–base–acid pretreatment with bulk combustion (ABA-BC) or after a newly developed acid–base–wet oxidation pretreatment with stepped combustion (ABOX-SC). The samples (charcoal) came from the earliest occupation levels of the Devil's Lair site in southwestern Western Australia. Initial occupation of this site was previously dated 35,000 14C yr B.P. Whereas the ABA-BC ages are indistinguishable from background beyond 42,000 14C yr B.P., the ABOX-SC ages are in stratigraphic order to ∼55,000 14C yr B.P. The ABOX-SC chronology suggests that people were in the area by 48,000 cal yr B.P. Optically stimulated luminescence (OSL), electron spin resonance (ESR) ages, U-series dating of flowstones, and 14C dating of emu eggshell carbonate are in agreement with the ABOX-SC 14C chronology. These results, based on four independent techniques, reinforce arguments for early colonization of the Australian continent.

This paper reports the discovery of a visible, tephra horizon of Late-glacial age from the site of Loch Ashik in the Isle of Skye, the Inner Hebrides, Scotland. Although the tephra shards have a bimodal geochemical composition identical to that of the Vedde Ash (a well known marker horizon within Late-glacial sequences. The horizon at Ashik is dominated by basaltic shards and devitrified tephra shards, giving the layer its characteristic black colour. Only rhyolitic shards have previously been reported from Vedde Ash horizons in the British Isles. This new evidence raises some important questions about the factors that govern the distribution and accumulation of basaltic tephra, and about the methods used to detect ash shards in basins distal to centres of volcanic activity. Copyright © 2001 John Wiley & Sons, Ltd.

AMS radiocarbon dates were obtained from Salix herbacea leaves, Carex seeds, and bulk organic detritus from a lake sediment profile of Wisconsinan (Weichselian) Lateglacial age in SW Ireland. There is a systematic age difference between the dated series from the two types of macrofossils, with ages obtained from Salix herbacea leaves being 900 to 1500 14C years younger than those obtained from Carex seeds. The latter tend to be more in accord with dates from the total organic detritus in the lake sediment, although the bulk organic fraction invariably registered the older ages. Intact survival of the fragile Salix leaves indicates that they are unlikely to have been physically transferred within the sediment matrix and/or otherwise reworked from the surrounding catchment. Hence, these macrofossils are the more likely to be contemporaneous with the time of deposition. However, there is no significant correlation between measured 14C age and depth in the Salix values, which scatter over a range of 700 14C years. In contrast, the age/depth relationship for Carex shows a significant reversal, possibly reflecting the redeposition of these macrofossils, and therefore giving radiocarbon ages that are anomalously old. The data have important implications for the dating of lake sediment sequences by AMS radiocarbon measurement of terrestrial plant macrofossils.

Stratigraphic records from four sequences in Britain that span the Last Glacial-Holocene transition (c. 15.0–11.5 cal ka bp) are summarized and compared using a calibrated timescale. Palaeoclimatic changes are defined using temperature estimates based on coleopteran data at two of the sites, and chironomid assemblages at the other sites. An attempt is made to distingish between the timing of (a) climate shifts and (b) ecosystem responses at all four sites. The British data are compared with the GRIP ice-core record, recently advocated by Bjorck et al. as the type-sequence for the Last Termination in the North Atlantic region. There is a degree of compatibility between the British and GRIP palaeoclimatic records. The clearest climatic signals in the British lake records are (a) a period of warm conditions (a thermal maximum) between 15.0 and 14.5 cal ka BP, which equates approximately with GRIP zone GI-le; (b) the onset of climatic cooling, which appears to have commenced during GRIP zone GI-le, at c. 14.5 cal ka bp; (c) a period of marked climatic instability from 14.4 to 12.7 cal ka BP, the regional effects of which are difficult to resolve using the evidence presently available; (d) further climatic cooling, which commenced at around 13.0 cal ka bp, after which the lake biota, catchment soils and vegetation cover, at least in some parts of Britain, did not recover until the onset of the Holocene; (e) continued climatic cooling, with the most severe impact on lake ecosystems occurring during the period c. 12.6 to 11.5 cal ka bp.

The overall aim of the TIGGER IIb project is to increase our understanding of the manner and rates by which ecosystems responded to climate changes during the Last Glacial-Holocene transition. Success in this venture requires better constrained palaeoenvironmental reconstructions than have been achieved thus far, and the TIGGER project focused, in particular, on three main aims: (1) off-setting the limitations of conventional radiocarbon dating, in order to provide a more secure chronology of events; (2) increasing the resolution and precision of palaeoclimatic reconstructions; (3) widening the scope of site-specific palaeoecological investigations. In this paper we focus on the first of these strategies, and describe the progress made in developing a more coherent timescale for the climate history of the Lateglacial period. This has been achieved by using a number of independent methods, including calibration of AMS radiocarbon dates obtained from terrestrial plant macrofossils, MCR estimates of summer temperatures based on coleopteran records, analysis of stable carbon isotope ratios in terrestrial plant macrofossils and tephrochronology. Following Bjorck et al.9s 1998 recommendations, we integrate the new results to construct a provisional event stratigraphy for the Last Glacial-Holocene transition in the British Isles, which is based on a sequence of features that are believed to be time-parallel. This approach is considered to provide a more coherent framework for direct comparison of the palaeoenvironmental evidence from Britain with that from elsewhere.

Bulk organic &3C records are presented from five last glacial-Holocene transition lacustrine sequences (14-9 ka '4C BP) on a north-south transect across the British Isles. The data confirm that bulk organic 63C is an amalgam of processes operating within the catchment and lake systems. Significant shifts in bulk organic 813C values are recorded across important climatic boundaries, though their synchroneity is questionable. Either the shifts are not observed at the sites or they do not appear to be synchronous, suggesting that site-specific factors play an important role. Potential controls are discussed within the context of climatic change in the North Atlantic region.

A technique is described for the extraction of rhyolitic microtephra from inorganic Lateglacial lake sediments. This technique was successfully applied by Lowe and Turney (1996) and is an adaption of the method described by Pilcher & Hall (1992) for application to Holocene peat deposits. It uses a density separation procedure to concentrate any microtephra component in lake sediments and was applied to the investigation of a lake sediment succession from a small basin in NE Scotland. Using this approach is was possible to define quantitatively for the first time the presence of the Vedde Ash tephra layer on the British Isles.

Evidence is presented to show that two measurable concentrations of microtephra particles can be detected in deposits of Late Devensian Late-glacial age in three sites in Scotland. One layer is attributed to the Vedde Ash, a marker horizon within the Younger Dryas chronozone. The second is a new tephra reported for the first time, which we name the Borrobol Tephra. This occurs consistently near the base of the Late-glacial Interstadial organic sediments at each site, and is thought to date to around 12.5 14C ka BP. Geochemical determinations using an electron microprobe confirm the identification of the Vedde Ash, suggest the Borrobol Tephra to have an Icelandic origin, and demonstrate the consistency of the geochemical signals at all three sites. © 1997 John Wiley & Sons, Ltd.

A thin layer of micro-tephra particles has been discovered in a lake sediment sequence from Sutherland, Scotland. The tephra is attributed to the Vedde Ash on the basis of ash geochemistry. The Vedde Ash, which has been dated to c. 10 300 radiocarbon years BP and which was thus deposited during the Younger Dryas chronozone, has previously been reported from lake sequences in Norway, from sediment cores from the NE North Atlantic and from Greenland ice cores, but this is the first reported record from the British mainland. It is likely that this ash layer also occurs in other lake sediment sequences in northern Britain, thus providing the potential for more precise correlations of Younger Dryas sequences than has hitherto been the case. The way in which correlation by tephrochronology may revolutionize approaches to reconstructing the sequence of events in theNE Atlantic region during the last glacial-interglacial transition is briefly considered.

Stable carbon isotope data that span part of the last glacial–interglacial transition (ca. 14-9 ka 14C BP; ca. 15–11 ka cal. BP), and which derive from organ-specific plant macrofossils recovered from two lake sediment profiles in the UK and one in Norway, are compared. The recorded temporal variations show similar trends, which, over a millennial time-scale appear to parallel the main drift in δ18O as determined for the GRIP ice-core. It is postulated that some smaller scale variations in the δ13C profiles may reflect the shorter term oscillations in δ18O values evident in the GRIP record, although this is less certain. Overall, however, the results suggest that stable carbon isotope measurements based on organ-specific terrestrial plant macrofossils may provide (i) a means for establishing correlations between terrestrial successions and (ii) additional paleoenvironmental information, as the apparent ‘shadowing’ of the GRIP record indicates a common forcing mechanism for both Greenland δ18O and northwest European δ13C variations. From the evidence available we suggest that the recorded δ13C variations reflect fluctuations in air temperature and/or changes in water vapour pressure in the atmosphere. © 1997 John Wiley & Sons, Ltd.

We present δ13C data from both bulk organic sediment samples and terrestrial plant macrofossils from five high-resolution sedimentary sequences from the United Kingdom from which extensive multiproxy data sets have been obtained. These span the last glacial-interglacial transition. Chronological control has been provided by radiocarbon dating and/or tephrochronology. The results demonstrate that significant shifts in bulk organic δ13C can be identified at key climatic transitions in most of the sites. The data are affected by site-specific influences that restrict their use as chronological markers. However, terrestrial plant macrofossil records are more consistent and reveal shifts that appear to be synchronous and which therefore offer a basis for interregional correlation as well as significant paleoenvironmental information.

Rasmussen and Svensson correctly point out that there is currently no satisfactory method to fully align the Greenland and Cariaco Basin records of climate change. However, our approach using interstadial onsets as tie-points allows direct comparison between radiocarbon dates and Greenland climate records. Crucially, both the standard Greenland and the merged Greenland-Cariaco time scales show that interstadial warming was associated with megafaunal genetic transitions.

Short Reports more generally to gain an appreciation of what information is in existence, its location and how to obtain it. The creation of the Bowen Basin Collection originated as a response to this. Information within the collection largely (but not solely) derives fiom material amassed throughout the nearly seven year course of the Bowen Basin Project. As the Collection took shape, major gaps in the information held and the incomplete nature of others were identified. Where possible and practical we have sought to address these gaps. More recently significant portions of the information held have derived from the private collections of individuals and families (Aboriginal and European) fiom throughout the region. While much of the information within the Collection comes from archives, libraries and the like, it also contains a great array and volume of primary information collected as part of the Bowen Basin Project. All information that forms the Collection has been systematically organised, in some instances collated/synthesised and turned into relational databases (Table l ) and is held in a single place within the region for access and use by a range of researchers. Protocols and procedures governing access to and use of the collection are in the final stages of development and implementation. Listings of information and databases held within the collection are available on the web site in four main categories: Archival Information; Cultural Heritage Databases; Oral History Tapes and the Photographic Collection. These listings are primarily provided to alert people to the range of information held within the region that is available for review and research and to provide 'metadata' regarding the creation, structure, contents, and access status of various elements of the collection. Project Research Areas, Progress Snapshots and Papers and Publications These areas of the web site provide snapshots of the variety of research areas pursued within Stage 2 of the Bowen Basin Project that have underpinned many of the above specific developments. This includes aspects of the Project's fieldwork program, training and capacity-building aspects of the Project, and student research projects that have been undertaken. Details on a number of specific sub-projects such as community-based land management and GIS workshops, Gangulu traditional associations with the Dawson and Callide valleys and virtual cultural tourism as a cultural heritage management strategy are also provided on these pages. Also available for review are summaries of the various publications and papers that have derived from the Bowen Basin Project. This includes unpublished conference and workshop papers and in the case of the Project's GIS and movement to web-based mapping applications, project discussion papers as further background to these areas of the web site. Where appropriate, full versions of these have also been provided for further inspection or download. Wbere ? The Bowen Basin www.bowenbasin.com web site can be found at References Godwin, L., M.J. Morwood, S. L'Oste-Brown and A. Dale. 1999 Bowen Basin Aboriginal Cultural Heritage Project: a strategic regional approach for research and management. Australian Archaeology 48:29-34. Australian Archaeology, Number 5 3 , 200 1 L'Oste-Brown, S., L.Godwin and C-Porter 1 W8a Towards and Indigenous Social and Cultural Lamhcape of the Bwen Basin Cultural Heritage Monograph Series, Volume 2. Brisbane: Queensland Department of Environment. L'Oste-Brown, S., L. Godwin, and J. Scrifignano 1998b. Towards an Indigenous Social and Cultural Landscape of the Bowen Basin (GIS Component). GIS User 28:33-8. L'Oste-Brown, S., L. Godwin and J. Scrimgnano 2001 Issues and Solutions for the Management of Aboriginal Cultural Heritage Information in the Bowen Basin, Central Queensland. In AURlSA (ed.), Proceedings of the 28th Annual Conference of the Australasian Urban and Regional Information Systems Association (A URISA). Canberra: AURISA. Queensland Department of the Premier and Cabinet. 1999 Queensland Indigenous Cultural Heritage Review: Draft Model for New Legislation. Brisbane: Queensland Government. NEW ABOX AMS-'~C AGES REMOVE DATING ANOMALIES AT PURITJARRA ROCK SHELTER M.A. Smith Research and Development section, National Museum of Australia, Canberra, ACT 260 1, Australia. M.I. Bird Research School of Earth Sciences, Australian National University, Canberra, ACT 0200, Australia. C.S.M. Turney Centre for Quaternary Research, Geography Department, Royal Holloway, University of London, Egham, Surrey TW20 OEX, United Kingdom. L.K. Fifield, G.M. Santos, P.A. Hausladen and M.L. di Tada Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200, Australia A robust site chronology generally requires a large series of age determinations, preferably using a range of dating methods and with sufficient dated samples to allow internal corroboration of the age of individual layers. One of the handful of Australian archaeological sites to meet these criteria is Puritjarra rock shelter in central Australia. The chronology forthis site rests on a published series of 3 1 radiocarbon assays on charcoal and nine luminescence dates on sediments (Smith et a1 1997) together with ten radiocarbon dates that have become available subsequently. The history of research at this site highlights the potential weakness of site chronologies that rely on only a handful of radiocarbon determinations to establish the age of late Pleistocene units. Extensive work on the chronology of Puritjarra since the preliminary reports (Smith 1987, 1 989) has shown that levels initially dated to 22,000 BP are in fact much older: -27,000-32,000 BP (14c) or 35,000 years ago (TL). By the early 1990s the age-depth relationship at this site was better understood and the overall trend of the radiocarbon series was

Widespread dispersal of Icelandic tephra: how does the Eyjafjoll eruption of 2010 compare to past Icelandic events?

Subsamples of charcoal from a number of different excavation contexts at the early modern human (Homo sapiens) site of Niah Great Cave (Malaysia) were accelerator mass spectrometry (AMS) 14C dated. Samples were prepared using one of a number of different methods: untreated (control); acid–base–acid (ABA); and acid–base–wet oxidation with stepped combustion (ABOX-SC) after Bird et al. (1999). The results show that for material younger than ∼25 ka BP there is little difference between the two chemical pretreatment methods and the control. For charcoal beyond ∼25 ka BP, however, there are differences of up to 4000 a, with ABOX-SC ages being consistently older. This is argued to be a more effective pretreatment method for decontaminating charcoal samples prior to radiocarbon dating. For radiocarbon dating charcoals greater than ∼25 ka BP, the ABOX-SC pretreatment and combustion approach appears to be the most rigorous method for developing a robust chronological framework for tropical sequences and should be more widely applied in contexts where the material being dated is likely to be ancient. The new chronology developed for Niah Cave based on this technique suggests that the earliest human evidence dates back to at least 45 ka BP and may extend significantly earlier than this based on the recent discovery of lithics 50 cm below the earliest dated charcoal. Copyright © 2008 John Wiley & Sons, Ltd.

The newly-detected Icelandic Penifiler Tephra occurs in the mid-Interstadial sediments of a number of Scottish Lateglacial sequences. 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. Such chemical similarity may account for some of the confusion regarding the age and stratigraphic position of Borrobol-like ash layers occurring elsewhere. However, 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 here 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 ash layers, suggesting either a basaltic phase associated with these eruptions, or coincident eruptions from a separate basaltic volcanic centre. Such basaltic populations may strengthen correlations with basaltic 2 ashes recently detected in the NGRIP ice-core. The detection of the new Penifiler Tephra contributes to the regional tephrostratigrapic framework, and provides an additional isochron for assessing the synchroneity of palaeoenvironmental changes during the Interstadial. The true stratigraphic nature and, therefore, age of the Borrobol Tephra, however, is persistently difficult to resolve making its use as an isochron more problematic.

The Campanian province has a rich history of human interaction with volcanic eruptions. In a region currently inhabited by 3 million people, it is crucial to have precise and accurate geochemical characterization of volcanic units within the region so as to identify the spatial distribution of past events. Furthermore, tephrochronology is becoming an important tool in the region for correlating past environmental records. Unfortunately, many of the key units have been geochemically analysed using relatively imprecise methods, making correlation problematic. Although robust correlations have been established in the Campanian province using a range of methods, including stratigraphy and geochronology, more distal correlation requires precise geochemical characterisation of individual glass shards. Here we report major oxide data, geochemically characterising 17 key tephra units within the Campanian province using wavelength dispersive spectrometry (WDS). The new data confirm the trachytic nature of most of the eruptions. To effect more precise correlations between units (especially in distal locations), proximal units must be individually analysed for major oxides using WDS on the vitreous phase, and statistically analysed for robust correlations. In cases where similar geochemistry exists, analysis of trace and rare earth elements may be necessary.

The study of (Palmer et al 2015 Environ. Res. Lett. 10 124002) details a spatial reconstruction of drought across eastern Australia and New Zealand over the last 500 years. The authors used a global 0.5° by 0.5° gridded network of the self-calibrating Palmer drought severity index (scPDSI) spanning 1901–2012 as the basis for a nested point-by-point regression to reconstruct austral summer (DJF) scPDSI for this region. Their study used 176 tree rings from New Zealand, Indonesia and Australia, and one coral record from the Great Barrier Reef. In their paper Palmer et al (2015) compared three publically available proxy records and reconstructions derived from the Law Dome ice core (East Antarctica) to their reconstructed scPDSI. These were the LD summer sea salt (LDsss) series, which is a proxy for Western Pacific sea surface temperature and subtropical eastern Australian rainfall (Vance et al 2013 J. Clim. 26 710–25, 2015 Geophys. Res. Lett. 42 129–37, Tozer et al 2016 Hydrol. Earth Syst. Sci. 20 1703–17), and two Interdecadal Pacific Oscillation (IPO) reconstructions produced using two independent methods, namely the Piece-wise Linear Fit (PLF) and Decision Tree (DT) series (Vance et al 2015 Geophys. Res. Lett. 42 129–37, 2016 Clim. Past 12 595–610). We show that the treatment of the Law Dome LDsss record and the PLF and DT IPO reconstructions mis-characterizes both the utility and targets of the three records.

A continental-scale model of Holocene Australian hunter-gatherer demography and mobility is generated using radiocarbon data and geospatial techniques. Results show a delayed expansion and settlement of much of Australia following the termination of the late Pleistocene until after 9,000 years ago (or 9ka). The onset of the Holocene climatic optimum (9-6ka) coincides with rapid expansion, growth and establishment of regional populations across ~75% of Australia, including much of the arid zone. This diffusion from isolated Pleistocene refugia provides a mechanism for the synchronous spread of pan-continental archaeological and linguistic attributes at this time (e.g. Pama-Nyungan language, Panaramitee art style, backed artefacts). We argue longer patch residence times were possible at the end of the optimum, resulting in a shift to more sedentary lifestyles and establishment of low-level food production in some parts of the continent. The onset of El Niño - Southern Oscillation (ENSO; 4.5-2ka) restricted low-level food production, and resulted in population fragmentation, abandonment of marginal areas, and reduction in ranging territory of ~26%. Importantly, climate amelioration brought about by more pervasive La Niña conditions (post-2ka), resulted in an intensification of the mobility strategies and technological innovations that were developed in the early- to mid-Holocene. These changes resulted in population expansion and utilization of the entire continent. We propose that it was under these demographically packed conditions that the complex social and religious societies observed at colonial contact were formed.

Continuous pollen and charcoal records, predominantly from well dated marine sediments, provide a good spatial coverage of patterns of change in vegetation, climate and biomass burning within the northern Australian - southern Indonesian region through the late Quaternary period. Northern hemisphere ice volume and monsoon forcing is conspicuous on orbital timescales with general expansion of wetter communities under higher precipitation during interglacials and their contraction under drier glacials. However, this picture is regionally complicated by both southern hemisphere monsoon and long term El Nino - Southern Oscillation influences. The charcoal records suggest a complex pattern of burning with generally more frequent or intense fires during climate transitions and also during drier periods except when and where fuel availability became a limitation. Superimposed on this largely cyclical pattern is a trend, within the last 300,000 to 200,000 years, towards more open canopied vegetation and increased...

High-precision correlation of palaeoclimatic and palaeoenvironmental records is crucial for testing hypotheses of synchronous change. Although radiocarbon is the traditional method for dating late Quaternary sedimentary sequences, particularly during the last glacial–interglacial transition (LGIT; 15–9 ka), there are inherent problems with the method, particularly during periods of climate change which are often accompanied by major perturbations in atmospheric radiocarbon content. An alternative method is the use of tephras that act as time-parallel marker horizons. Within Europe, numerous volcanic centres are known to have erupted during the LGIT, providing considerable potential for high-precision correlation independent of past radiocarbon fluctuations. Here we report the first identification of the Vedde Ash and Askja Tephra in Ireland, significantly extending the known provenance of these events. We have also identified two new horizons (the Roddans Port Tephras A and B) and tentatively recognise an additional horizon from Vallensgard Mose (Denmark) that provide crucial additional chronological control for the LGIT. Two phases of the Laacher See Tephra (LST) are reported, the lower Laacher See Tephra (LLST) and probably the C2 phase of the Middle Laacher See Tephra (MLST-C2) indicating a more northeasterly distribution of this fan than reported previously. Copyright © 2006 John Wiley & Sons, Ltd.

[1] The climatic effects of historical volcanic eruptions are well documented in the literature. What are less certain however, are the effects of eruptions on more distant environments, particularly vegetation. Here we present subannual delta(13)C records from two high-resolution Irish oak ( Quercus spp.) chronologies that span the Laki (Grimsvotn) 1783-84 and Tambora 1815 eruptions. In both instances, a significant depletion in delta(13)C is recorded within the trees following the eruption (similar to 1.8%o). Historical meteorological datasets from observatories near to the trees sampled demonstrate that the shifts in carbon isotopic content cannot be accounted for by changes in local climate. We postulate atmospheric loading of ejecta from the eruptions resulted in significantly reduced irradiance, increasing discrimination within the trees.

Excavations at Liang Bua, a large limestone cave on the island of Flores in eastern Indonesia, have yielded evidence for a population of tiny hominins, sufficiently distinct anatomically to be assigned to a new species, Homo floresiensis. The finds comprise the cranial and some post-cranial remains of one individual, as well as a premolar from another individual in older deposits. Here we describe their context, implications and the remaining archaeological uncertainties. Dating by radiocarbon (14C), luminescence, uranium-series and electron spin resonance (ESR) methods indicates that H. floresiensis existed from before 38,000 years ago (kyr) until at least 18 kyr. Associated deposits contain stone artefacts and animal remains, including Komodo dragon and an endemic, dwarfed species of Stegodon. H. floresiensis originated from an early dispersal of Homo erectus (including specimens referred to as Homo ergaster and Homo georgicus) that reached Flores, and then survived on this island refuge until relatively recently. It overlapped significantly in time with Homo sapiens in the region, but we do not know if or how the two species interacted.

The oxygen and carbon stable-isotope ratios from fossil snail shells within a small intramontane lake in southwest Turkey are used to highlight the potential, and problems, of using freshwater snail carbonate as a palaeoenvironmental proxy. Two species (Gyraulus piscinarum and Valvata cristata) yielded different isotope ratios at the same sampling intervals, probably due to differences in water-isotope composition between different microhabitats. Isotope ratios from a number of individual shells from the same sampling intervals (representing 7–25 years), show large ranges (up to 8‰ for 18O) for each species. Only by analysis of a significant number of species-specific shells (5) from each sampling interval can a true understanding of environmental change be obtained. Averages of the data provide an insight into longer-term climatic variation while the ranges provide an estimate of short-term (decadal) environmental variability.

After his polar vessel became trapped in shifting sea ice, Chris Turney defends the scientific basis of the expedition.