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In hot environments, collagen, which is normally targeted when radiocarbon (14C) dating bone, rapidly degrades. With little other skeletal material suitable for 14C dating, it can be impossible to obtain dates directly on skeletal materials. A small amount of carbonate occurs in hydroxyapatite, the mineral phase of bone and tooth enamel, and has been used as an alternative to collagen. Unfortunately, the mineral phase is often heavily contaminated with exogenous carbonate causing 14C dates to underestimate the true age of a sample. Although tooth enamel, with its larger, more stable crystals and lower porosity, is likely to be more robust to diagenesis than bone, little work has been undertaken to investigate how exogenous carbonate can be effectively removed prior to 14C dating. Typically, acid is used to dissolve calcite and etch the surface of the enamel, but it is unclear which acid is most effective. This study repeats and extends earlier work using a wider range of samples and acids and chelating agents (hydrochloric, lactic, acetic and propionic acids, and EDTA). We find that weaker acids remove carbonate contaminants more effectively than stronger acids, and acetic acid is the most effective. However, accurate dates cannot always be obtained.

Several scientific expeditions surveyed the ocean during the 19th century, gathering a wealth of interdisciplinary data as well as samples of different kinds. The latter are currently held by museums worldwide, and are the subject of study in different sciences, offering a unique opportunity to access information which is not readily available elsewhere. This is the case for research involving the offset in 14C (or radiocarbon) activity between the ocean and the atmosphere, termed the Marine Reservoir Effect (MRE), which is responsible for apparent 14C ages in marine material. The quantification of this discrepancy is crucial for the 14C dating tool since corrections must be applied for the accurate calibration of marine 14C ages. Nevertheless, the difficulty of finding suitable material for assessing the MRE contributes to the current scenario of scarce and patchy data. Here we propose the use of samples collected during well-documented 19th-century scientific expeditions in order to overcome the lack of information that prevents the use of many museum specimens in MRE studies. Approximately 60 mollusk shells and a sea urchin, collected from the coast of Brazil, were analysed for their radiocarbon age, δ13C and δ18O. The MRE is variable, with considerably high values occurring at specific spots along the shoreline. The data indicate a rather large area of upwelling influence on the southeastern coast of Brazil and possible dissolution of 14C-free limestone in the northeast. The results shed light on processes affecting the 14C concentration of Brazilian coastal waters, bearing implications for palaeoenvironmental and archaeological studies performed in the region. Moreover, the data generated in this study will be useful for the validation of 14C simulations in numerical models. Finally, this paper offers a discussion of the importance of natural history collections which looks beyond the preservation of our biodiversity.

We present a high-resolution seawater radiocarbon (Δ14C) record from a Porites coral collected from Masthead Island in the southern Great Barrier Reef (GBR) covering the years 1945–2017. The Δ14C values from 1945–1953 (pre-bomb era) averaged –49‰. As a result of bomb-produced 14C in the atmosphere, Δ14C values started to rise rapidly from 1959, levelled off at ∼131‰ in the late 1970s and gradually decreased to ∼40.3‰ by 2017 due to the decrease in the air-sea 14C gradient and the overturning of the 14C ocean reservoir (i.e., surface ocean to subsurface ocean; atmosphere to surface ocean). The Masthead Island record is in agreement with previous 14C coral records from the southern GBR. A comparison between surface ocean and atmospheric Δ14C suggests that, since 2010, the main reservoir of bomb-derived 14C has shifted from the atmosphere to the surface ocean, potentially resulting in reversed 14C flux in regions where the CO2 gradient is favorable. The high-resolution Masthead coral Δ14C sheds light on long-term variability in air-sea exchange and GBR regional ocean dynamics associated with climate change and in conjunction with the previous records provides a robust seawater 14C reference series to date other carbonate samples.

International audience; The burial mound of Le Tumulus des Sables, southwest France, contains archaeological artefacts spanning from the Neolithic to the Iron Age. Human remains have been found throughout the burial mound, however their highly fragmented state complicates the association between the burial mound structure and the archaeological material. Radiocarbon dating and isotopic analyses of human teeth have been used to investigate the chronology, diet and mobility of the occupants. Radiocarbon dating shows that the site was used for burials from the Neolithic to Iron Age, consistent with the range of archaeological artefacts recovered. δ 13 C and δ 15 N values (from dentine collagen) suggest a predominately terrestrial diet for the population, unchanging through time. 87 Sr/ 86 Sr (on enamel and dentine) and δ 18 O (on enamel) values are consistent with occupation of the surrounding region, with one individual having a δ 18 O value consistent with a childhood spent elsewhere, in a colder climate region. These results showcase the complex reuse of this burial mound by a mostly local population over a period of about 2000 years.

We investigated the possibility of increasing the 14C AMS efficiency and maximizing C− beam currents by modifying sample cathode geometry and material. Previously, we reported results which showed an increase in C− beam current and improved ionization efficiency when reducing the cathode sample well diameter from 1 mm to 0.75 mm and using zinc inserts, pressed into the aluminum cathode holder [4]. In this study we expand that effort by using cathodes with inserts made of Fe, Mo, Ni, Ti, Cu, and Zn. We pressed cathodes with 100 μg of Oxalic Acid I (OX-I) and ran them to exhaustion. 12C beam currents, 14C counts, and graphite weight were used to determine ion source efficiency.

Deep-sea corals are a highly diverse group of marine organisms, several of which are characterised by slow growth and extreme longevity up to thousands of years. Due to their fragile forms, skeletal composition, and location, they are vulnerable to various anthropogenic threats, with some groups expected to have little to no ability to recover. Within the New Zealand region an understanding of age and growth parameters and recovery potential for some deep-sea coral fauna is being developed, but a limited understanding remains for some of the key Antipatharian black coral fauna. Ten individual colonies of the black coral species Bathypathes patula were sourced from the National Institute of Water and Atmospheric Research Invertebrate Collection for the purposes of this age estimation study. Corals were selected based on their size, completeness of the colony (whole colony from base to tip), and the regional water mass within which they grew. Coral samples from the Chatham Rise, east of New Zealand, and the Bay of Plenty, north-eastern New Zealand, were selected as the water masses for these two regions are reasonably well understood. Thin section preparations of the main stem of the 10 specimens of B. patula were observed with compound microscopes. Two interpretation protocols were used to describe the zone structures observed, both the coarse wide zones and the thin fine zones, and counts were then made of these structures. Four of the specimens were also sampled for radiocarbon assay. The radiocarbon isotope (14C) age data results were used to independently verify if either of the developed zone counting protocols reflected annual periodicity. Neither method was verified, indicating zone counting protocols could not be used to generate reliable age estimates for B. patula. Twenty radiocarbon assays from four specimens were used to derive the age and growth rate estimates presented here. The radiocarbon results from this work show B. patula to be a long-lived species, attaining ages in excess of 385 years, with linear growth rates of 5.2-9.6 mm/yr, and radial growth rates ranging from 11.1 to 35.7 mm/yr. The delicate nature of these organisms along with their longevity and slow growth rates means a low resilience and low recoverability from anthropogenic activities such as fishing and mining.

Calving cousins Walczak et al. report that increases in Pacific Ocean ventilation and periods of rapid production of icebergs from the Cordilleran Ice Sheet during the last glacial period preceded episodic iceberg discharges into the Atlantic Ocean (see the Perspective by Jaeger and Shevenell). Marine sediments from the Gulf of Alaska show that increases in vertical mixing of the ocean there correspond with intense iceberg calving from the ice sheet that covered much of high-latitude western North America and that these changes occurred before the analogous Heinrich events in the North Atlantic. Thus, these Pacific climate system reorganizations may have been an early part of a cascade of dynamic climate events with global repercussions. Science , this issue p. 716 ; see also p. 662

We examined the radiocarbon (14C) reservoir effect in Lake Kutubu using tephrochronology and terrestrial plant material to deliver a precise age-depth profile and sedimentation rates for this lake. Based on the presence of two tephra horizons (Tibito and Olgaboli), we found a reservoir age offset in sediments of between 1490 and 228014C yr using the sediment ages derived from the lead-210 (210Pb) dating method. The live submerged biological samples collected exhibited a higher reservoir age offset than the sediment. This is most likely a result of delayed transport of “bomb”14C from the atmosphere to aquatic and sedimentary system. The14C reservoir effect increased with distance from the lake inlet and also decreased with depth. Dissolution of14C-depleted carbon from surrounding limestone and direct in-wash of old soil or vegetation remnants from the catchment are the most likely causes of the14C reservoir effect. Based on limestone areas mapped in Papua New Guinea, we indicate lakes which may be subject to a significant14C reservoir effect. The results of this study demonstrate the magnitude of the14C reservoir effect in lakes and provide insights to the correct interpretation of past environmental and archaeological events in PNG.

Tibito Tephra was first recorded in the central highlands of Papua New Guinea (PNG) in 1971. By the late 1970s, the tephra had been mapped across tens of thousands of square kilometres, traced to i...

Over the last decade, two major calving events of the Petermann Ice Tongue in Northwest Greenland have led to speculation on its future stability and contribution to further Greenland Ice Sheet mass loss. However, it has been unclear if these events are anomalous or typical within the context of limited historical observations. We extend the historical record of the floating ice tongue using the stratigraphy of Petermann Fjord sediments to provide a longer-term perspective. Computed tomography (CT) scans, X-Ray Fluorescence (XRF) scans, Ice-Rafted Debris (IRD) counts, and the magnetic properties of specific particle size fractions constrain changes in depositional processes and sediment sources at our core sites, allowing for reconstructions of past behavior of the Petermann Ice Tongue. Radiocarbon dating of foraminifera, 210Pb, and paleomagnetic secular variation (PSV) provide age control and help to address uncertainties in radiocarbon reservoir ages. A floating ice tongue in Petermann Fjord formed in late glacial time as Petermann Glacier retreated from an advanced grounded position. This paleo-ice tongue broke-up during the early Holocene when high northern latitude summer insolation was higher than present. After gradual regrowth of the ice tongue associated with regional cooling, the ice tongue reached its historical extent only within the last millennium. Little or no ice tongue was present for nearly 5000 years during the middle Holocene, when decadal mean regional temperatures are estimated to be 0.8–2.9 °C higher than preindustrial (1750 CE) and seasonal sea-ice in the Lincoln Sea was reduced. This pre-historical behavior shows that recent anthropogenic warming may already be in the range of ice tongue instability and future projected warming increases the risk of ice tongue break-up by the mid-21st Century.

The Australian lungfish has been studied for more than a century without any knowledge of the longevity of the species. Traditional methods for ageing fish, such as analysis of otolith (ear stone) rings is complicated in that lungfish otoliths differ from teleost fish in composition. As otolith sampling is also lethal, this is not appropriate for a protected species listed under Australian legislation. Lungfish scales were removed from 500 fish from the Brisbane, Burnett and Mary rivers. A sub–sample of scales (85) were aged using bomb radiocarbon techniques and validated using scales marked previously with oxytetracycline. Lungfish ages ranged from 2.5–77 years of age. Estimated population age structures derived using an Age Length Key revealed different recruitment patterns between river systems. There were statistically significant von Bertalanffy growth model parameters estimated for each of the three rivers based on limited sample sizes. In addition, length frequency distributions between river systems were also significantly different. Further studies will be conducted to review drivers that may explain these inter-river differences.

Variability in the southwest (SW) Pacific Ocean circulation is influenced by the changes in the South Pacific subtropical gyre and its western boundary current, the East Australian Current (EAC). The EAC plays a significant role in transporting warm, well-ventilated, nutrient-poor waters to more temperate higher latitudes. Recent climate changes associated with EAC intensification have led to anomalous warming in the South Tasman, with implications for marine ecosystems and environment. A clear understanding of the significance of these changes requires knowledge of past natural variability. Here we have reconstructed a 4500 year record of regional sea surface radiocarbon reservoir ages (R) and local reservoir effects (ΔR). Our results reveal the centennial-scale variability over the last 4500 years, with R ranges as large as 390 14C yr. Older R (~410 14C yr) between 1610 to 1860 A.D. in our record, corresponding to the “Little Ice Age,” suggests a weaker influence of the EAC in the South Tasman. Between 4000 and 1900 cal years B.P., R and ΔR were significantly younger than the modern, with values of ~170 and −130 14C yr, respectively, indicating increased EAC transport of tropical waters into the South Tasman. We propose that the large R variability was influenced by strong and abrupt El Nino events which punctuated the muted El Nino–Southern Oscillation (ENSO) period in the mid-late Holocene and enabled increased westward flow of gyre waters into the SW Pacific. The strengthening of the EAC extension appears to have been a response to the precession-modulated ENSO-Southern Annular Mode interactions.

A new radiocarbon preparation facility was set up in 2010 at the Godwin Laboratory for Palaeoclimate Research, at the University of Cambridge. Samples are graphitized via hydrogen reduction on an iron powder catalyst before being sent to the Chrono Centre, Belfast, or the Australian National University for accelerator mass spectrometry (AMS) analysis. The experimental setup and procedure have recently been developed to investigate the potential for running small samples of foraminiferal carbonate. By analyzing background values of samples ranging from 0.04 to 0.6 mg C along with similar sized secondary standards, the setup and experimental procedures were optimized for small samples. “Background” modern 14C contamination has been minimized through careful selection of iron powder, and graphitization has been optimized through the use of “small volume” reactors, allowing samples containing as little as 0.08 mg C to be graphitized and accurately dated. Graphitization efficiency/fractionation is found not to be the main limitation on the analysis of samples smaller than 0.07 mg C, which rather depends primarily on AMS ion beam optics, suggesting further improvements in small sample analysis might yet be achieved with our methodology.

Radiocarbon measurements reveal that soil carbon is often hundreds to thousands of years old; significantly older than the annual flux of carbon through the soil would suggest. Models deal with this discrepancy by conceptualizing soil carbon as having fast and slow cycling pools. The Rothamsted Soil Carbon Model contains an inert pool for this reason. Here we use a unique record of time-series radiocarbon measurements from long-term trials to demonstrate that the inert pool is hardly inert, and that its mean age varies from 2000 to as little as 90 years depending on carbon flow through the soil. This finding suggests that the concept of truly inert organic matter requires redefinition to account for the enhanced probability that microorganisms will overcome barriers to previously inaccessible organic matter as their activity increases.

The last deglacial was an interval of rapid climate and sea-level change, including the collapse of large continental ice sheets. This database collates carefully assessed sea-level data from peer-reviewed sources for the interval 0 to 25 thousand years ago (ka), from the Last Glacial Maximum to the present interglacial. In addition to facilitating site-specific reconstructions of past sea levels, the database provides a suite of data beyond the range of modern/instrumental variability that may help hone future sea-level projections. The database is global in scope, internally consistent, and contains U-series and radiocarbon dated indicators from both biological and geomorpohological archives. We focus on far-field data (i.e., away from the sites of the former continental ice sheets), but some key intermediate (i.e., from the Caribbean) data are also included. All primary fields (i.e., sample location, elevation, age and context) possess quantified uncertainties, which—in conjunction with available metadata—allows the reconstructed sea levels to be interpreted within both their uncertainties and geological context.

To explore the transport of carbon into water masses from the surface ocean to depths of ∼ 1000 m in the southwest Pacific Ocean, we generated time series of radiocarbon ( Δ C 14 ) from fish otoliths. Otoliths (carbonate earstones) from long-lived fish provide an indirect method to examine the “bomb pulse” of radiocarbon that originated in the 1950s and 1960s, allowing identification of changes to distributions of 14C that has entered and mixed within the ocean. We micro-sampled ocean perch (Helicolenus barathri) otoliths, collected at ∼ 400 – 500 m in the Tasman Sea, to obtain measurements of Δ C 14 for those depths. We compared our ocean perch Δ C 14 series to published otolith-based marine surface water Δ C 14 values (Australasian snapper (Chrysophrys auratus) and nannygai (Centroberyx affinis)) and to published deep-water values (800–1000 m; orange roughy (Hoplostethus atlanticus)) from the southwest Pacific to establish a mid-water Δ C 14 series. The otolith bomb 14C results from these different depths were consistent with previous water mass results in the upper 1500 m of the southwest Pacific Ocean (e.g. World Ocean Circulation Experiment and Geochemical Ocean Sections Study). A comparison between the initial Δ C 14 bomb pulse rise at 400–500 m suggested a ventilation lag of 5 to 10 yr, whereas a comparison of the surface and depths of 800–1000 m detailed a 10 to 20 yr lag in the time history of radiocarbon invasion at this depth. Pre-bomb reservoir ages derived from otolith 14C located in Tasman Sea thermocline waters were ∼ 530 yr , while reservoir ages estimated for Tasman Antarctic intermediate water were ∼ 730 yr .

In a sediment core collected from an estuary in a rapidly urbanizing region in South East Queensland, Australia, we used multiple geochemical tracers to understand the provenance, form, and rate of accumulating organic matter (OM) focusing on the application of two tools often used in studies of soil OM: solid-state 13C nuclear magnetic resonance (NMR) spectroscopy and interpretation of radiocarbon (14C) data by modeling the uptake of the bomb-spike in atmospheric 14C. While elemental (C, N) and stable isotope (13C, 15N) data generally could not distinguish OM sources, these data did indicate that there has been a steady increase in nutrient loading to the estuary and that there were periodic deposition events where the OM was dominated by C3 terrestrial vegetation. The NMR results showed that the OM was primarily of terrestrial origin being dominated by lignin and stable char-like carbon compounds in all samples. The 14C data and modeling indicated that the OM was composed of a mixture of material with widely varying ages. In general, the OM was hundreds of years older than the age of the sediments as determined by fallout radionuclide dating (1950–2009 chronology), indicating that a large fraction of the OM has resided on the terrestrial landscape for a substantial period before being transported and buried in the estuary sediments. By applying this combination of techniques, we have been able to develop a coherent picture of a very complex deposition and accumulation history in these estuary sediments.

Sample preparation protocols for concentrating organic material from sediments for radiocarbon dating often include a large number of steps and the use of hazardous chemicals. Thus, these protocols are often problematic for pollen-poor sediments as material can get lost or may become degraded. Pyrite in samples for radiocarbon dating hinders an effective graphitisation process and thus needs to be removed during sample preparation. Standard protocols require the use of nitric acid, a strong oxidant that corrodes organic material. Therefore, the use of nitric acid needs to be avoided when preparing pollen-poor but pyrite-rich sediments. We present a method that minimises the sample preparation steps by replacing acid treatment with heavy liquid separation. Using non-toxic LST at a density of 2.0 g cm −3 is shown to be effective for separating the organic fraction from sulphides, silicates and carbonates. We applied this method to pyrite-rich and pollen-poor sediments from Western Australia that had previously been problematic to date. The successful AMS radiocarbon dating of all samples pre-treated with LST demonstrates the effectiveness of this method.

Bones from extinct Australian marsupials found at Spring Creek, Victoria, and in the Mowbray Swamp, Tasmania, have yielded scattered and anomalously young radiocarbon ages measured on collagen, gelatin or ultrafiltered gelatin. We resampled previously dated material from those two sites and from Mt Cripps, Tasmania, as well as a control sample from Zaglik, Russia, to compare chronologies based on XAD-2 purified total amino acid fractions and collagen purified by ultrafiltration (UF) or less rigorous methods. Our age from the control site bone gave a similar infinite age, while six out of seven other comparisons yielded radiocarbon ages on total amino acid fractions older than those previously measured on collagen or gelatin. The Palorchestes from Spring Creek yielded a date of >53500 BP.

We describe new radiocarbon-dated evidence for the late survival of beavers from an upland site in northern England. A wood specimen with beaver gnaw marks was recovered from the bank of the Scaup Burn in Kielder Forest in Northumberland. The marks were analysed, the tree species were identified and the sample was radiocarbon dated to between 1269 and 1396. Other wood remains in the same context suggest a most likely dating between 1330 and 1390. This find represents the most recent radiocarbon-dated physical evidence of beaver yet found in Britain, by at least 400 years. In conjunction with documentary and other archaeological evidence from the period, this discovery indicates beaver were present within the Tyne River catchment up until at least the 14th century ad. In addition, this find highlights the need to investigate all possible evidence of beaver fully when discovered and to remain open-minded about the possibility of making finds in unexpected locations and contexts.

Since the late 1980s, northern Iberia has yielded some of the earliest radiocarbon dated Aurignacian assemblages in Western Europe, probably produced by anatomically modern humans (AMHs). This is at odds with its location furthest from the likely eastern entry point of AMHs, and has also suggested to some that the Châtelperronian resulted from cultural transfer from AMHs to Neanderthals. However, the accuracy of the early chronology has been extensively disputed, primarily because of the poor association between the dated samples and human activity. Here, we test the chronology of three sites in northern Iberia, L'Arbreda, Labeko Koba and La Viña, by radiocarbon dating ultrafiltered collagen from anthropogenically modified bones. The published dates from Labeko Koba are shown to be significant underestimates due to the insufficient removal of young contaminants. The early (c.44 ka cal BP [thousands of calibrated years before present]) Aurignacian chronology at L'Arbreda cannot be reproduced, but the reason for this is difficult to ascertain. The existing chronology of La Viña is found to be approximately correct. Together, the evidence suggests that major changes in technocomplexes occurred contemporaneously between the Mediterranean and Atlantic regions of northern Iberia, with the Aurignacian appearing around 42 ka cal BP, a date broadly consistent with the appearance of this industry elsewhere in Western Europe This research was funded by a NERC Standard grant (NE/D014077/1) as part of the project 'Dating of the Middle-Upper Palaeolithic transition in western Europe using ultrafiltration AMS radiocarbon' for which we are extremely grateful. R. Wood was funded by a tied studentship to this grant. A. Villaluenga was funded by the Basque Government Ph.D. funding program. Roger Jacobi, British Museum, is thanked for discussions, invaluable advice in sample selection and bone identification. Javier Fortea, Universidad de Oviedo, is thanked for help in sample selection and interpretation of results from La Villa. Both sadly passed away during the course of this project Maite Izquierdo, Heritage Preservation, Basque Government, is thanked for help sampling bone from Labeko Koba. Excavation and research at l'Arbreda is funded by the Culture Ministry of Catalonia and the ministerial projects HAR2010-19120 (The Middle Palaeolithic of the L'Arbreda Cave) and HAR2010-22013 (Cultural, Paleoenvironmental and Chronological History of the Last Neanderthals and Early Modern Humans in the North of the Iberian Peninsula)

Fish otoliths from the Willandra Lakes Region World Heritage Area (south-western New South Wales, Australia) have been analysed for oxygen isotopes and trace elements using in situ techniques, and dated by radiocarbon. The study focused on the lunettes of Lake Mungo, an overflow lake that only filled during flooding events and emptied by evaporation, and Lake Mulurulu, which was part of the running Willandra Creek system. Samples were collected from two different contexts: from hearths directly associated with human activity, and isolated surface finds. AMS radiocarbon dating constrains the human activity documented by five different hearths to a time span of less than 240 years around 19,350 cal. BP. These hearths were constructed in aeolian sediments with alternating clay and sand layers, indicative of fluctuating lake levels and occasional drying out. The geochemistry of the otoliths confirms this scenario, with shifts in Sr/Ca and Ba/Ca marking the entry of the fish into Lake Mungo several years before their death, and a subsequent increase in the δ 18 O by ∼4‰ indicating increasing evaporation of the lake. During sustained lake-full conditions there are considerably fewer traces of human presence. It seems that the evaporating Lake Mungo attracted people to harvest fish that might have become sluggish through oxygen starvation in an increasingly saline water body ( easy prey hypothesis). In contrast, surface finds have a much wider range in radiocarbon age as a result of reworking, and do not necessarily indicate evaporative conditions, as shown by comparison with otoliths from upstream Lake Mulurulu.

Marine reservoir ages are a key element in calculating and constraining uncertainty in radiocarbon age estimates and are also essential to better understand regional ocean circulation. In this study, we present a new method to reconstruct long-term, high-resolution sea surface reservoir ages based on analysis of the organic skeleton of deep-sea (560 m) black coral (Anthozoa, Antipatharia). Our results confirm that antipatharians are extremely slow growing (typical radial growth rate for a South Pacific specimen around 0.03 mm/yr). Coupled uranium series and radiocarbon measurements were made on black coral collected live from the Norfolk Ridge (north Tasman Sea) to provide the first modern reservoir ages for this region. At the Norfolk Ridge, the average reservoir age between 1790 AD and 1900 AD was ∼330 years. This was followed by a steep decrease over time of about 70 years to 1950 AD (our most modern value). This indicates an increase in surface ocean ventilation of water masses in this region. These results are consistent with observational studies for the early twentieth century, which suggest significant changes in regional circulation of the southwest pacific.

This paper presents 29 radiocarbon dates from eight surface concentrations of shell and 10 test-pits across four shell middens at Long Point in the Coorong, South Australia. Results indicate that occupation of these sites was confined to the late Holocene period, post-2500 cal. BP. With the exception of one midden, which appears not to have been used after 500-300 cal. BP, all other sites suggest continued use until the recent past. This pattern fits with a proposed period of population expansion and intensification of resource use in the Coorong, along with more general changes known to have occurred in parts of coastal Australia during the mid- to late Holocene.

Little is known about growth rates of deep-water reef-forming corals or the rates at which these reefs accumulate. Such information is critical for determining the resilience of the reefs to anthropogenic impacts such as trawling and climate change. We radiocarbon date live-caught and sub-fossil samples of the bioherm-forming coral Solenosmilia variabilis collected from precisely known depths and locations by means of a remotely operated vehicle on seamounts south of Tasmania, Australia. The growth rate of colonies live-caught between 958 and 1,454 m, which spans most of the depth range of the species locally, ranged from 0.84 to 1.25 mm linear extension yr−1 and tended to be higher in the deeper-caught material. Analysis of skeletal microstructure suggests annual deposition of growth increments near the growing tips, but not closer to the base, as the skeleton is extended and thickened. Dating of sub-fossil material indicates S. variabilis has been present on Tasmanian seamounts for at least the last 47,000 yrs and a reef accumulation rate of 0.27 mm yr−1.

We report extension rates and growth patterns of the coralline red alga Sporolithon durum (rhodolith form) from New Caledonia. Alizarin red S staining was used to mark 43 rhodolith branches and helped determine extension rates over the rhodoliths' last living year. A combination of radiocarbon dating, major Mg/Ca ratio cycles and growth band determinations provided a chronological approach to characterise extension rates for 5 branches over the last 5 decades. A seasonal asymmetry in the extension rates was observed, with higher extension during the austral summer-fall-winter period, indicating that variations in ambient seawater temperature are not of major influence in the seasonal growth pattern of S. durum. At the sub-seasonal level, minor growth bands were observed with a maximum frequency of 14 d but were too variable to be considered as a reliable chronological tool. The concordance of the results from both the monitoring experiment over the year 2010 to 2011 and the chronological approach applied to the period 1968 to 2008 suggests that an extension rate (mean +/- SD) of 0.6 +/- 0.2 mm yr(-1) is typical of the S. durum community at the study site. However, annual extension rates varied considerably among branches and individuals. Long-term trends still appeared, such as a decrease during the early 1970s attributed to the impact of mining activity. A slight but consistent decrease was observed in the annual extension rates throughout the record and may reflect an ontogenic effect potentially enhanced by reduced light penetration due to increasing suspended particulate matter in the water column.

We have studied two young speleothems, SC4 from Smiths Cave (Christmas Island, eastern Indian Ocean) and WM7 from Wollondilly Cave (Wombeyan caves, SE Australia). Attempts to date these speleothems by the Th/U method have proved unsuccessful with some age reversals for SC4 due to multiple sources of non-authigenic Th. This method has also resulted in imprecise ages for WM7 because of low U concentrations (

We report the first uranium-series age estimates for rock art in China. Calcite bracketing a paint layer was used to constrain the age of a naturalistic outline hunter-gatherer painting in the Jinsha River area of northwest Yunnan Province (southwest China). The rock paintings in this region are unique in style and content compared with other bodies of rock art in China, which are dominated by Neolithic subject matter. The minimum and maximum ages were determined using isochron techniques on multiple samples of calcite from above and beneath the paint layer. A large painted deer head was dated to between 5738 and 2050 years. This painting and underlying flowstone are superimposed on older paintings that suggest the older paintings are at least 3400 years old, if not older than 5738 years. The results indicate for the first time that Jinsha River rock art is older than other forms of rock art in the region and show that rock art likely extends back to at least the transition from the Palaeolithic to Neolithic in this part of China.

Assigning accurate dates to hypersaline sediments opens important terrestrial records of local and regional paleoecologies and paleoclimatology. However, as of yet no conventional method of dating hypersaline systems has been widely adopted. Biomarker, mineralogical, and radiocarbon analyses of sediments and organic extracts from a shallow (13 cm) core from a hypersaline playa, Lake Tyrrell, southeastern Australia, produce a coherent age-depth curve beginning with modern microbial mats and extending to ~ 7500 cal yr BP. These analyses are furthermore used to identify and constrain the timing of the most recent change in hydrological regime at Lake Tyrrell, a shift from a clay deposit to the precipitation of evaporitic sands occurring at some time between ~ 4500 and 7000 yr. These analyses show the potential for widespread dating of hypersaline systems integrating the biomarker approach, reinforce the value of the radiocarbon content of biomarkers in understanding the flow of carbon in modern ecologies, and validate the temporal dimension of data provided by biomarkers when dating late Quaternary sediments.

A previous assessment of radiocarbon ( 14 C) dates from alluvial units in southeastern Australia revealed a gap in the geochronological record that coincides with the Holocene climatic optimum. Thisgapin the alluvial recordcanbe further refined usingoptically stimulatedluminescence (OSL). The chronology of Holocene river terraces on Widden Brook, a sandy alluvial stream in southeastern Australia, was established using 14 C and OSL techniques. Combined use of these independent techniques allows for a more rigorous assessment of the alluvial record. The robust chronology, consisting of 38 14 C and 11 OSL samples, permitted identification of significant deposi- tionalvariationwithin thecatchment,resulting fromlocalisedgeomorphicprocesses. Thethree terrace sequences identified yielded distinct chronologies, suggesting alluvial deposition at different times. The sequences exhibited a continuous chronology, which indicated continuous deposition throughout the Holocene. The chronology of terrace sequences within this catchment suggests that terrace formation can be attributed to localised geomorphic processes rather than climatic forcing. Copyright # 2010 John Wiley & Sons, Ltd. Supporting information can be found in the online version of this article.

In February 2007, a single stage AMS from the National Electrostatics Corporation (NEC) was installed at the Research School of Earth Sciences at the Australian National University. This instrument is equipped with a gas/graphite hybrid ion source allowing direct analysis of CO 2 as well as traditional graphite targets. The instrument was funded by an Australian Research Council grant and by a consortium of eight universities plus the CSIRO Division of Land and Water. Its purpose is to support integrated environmental and archaeological research and access is open to the wider research community. In the first year ∼1500 samples have been analysed. A precision of ∼3‰ is routinely observed. The background for processed graphite (coal, calcite, Carrera marble) is better than 45,000 years. This paper summarizes the first year of measurements.

We present a novel application for radiocarbon dating by aging 4 scales from a single large adult lungfish (Neoceratodus forsteri) from the Burnett River, in Queensland, Australia. The relict fish species lack a solid crystalline otolith, which precludes the use of the otolith annuli as a reliable age indicator. Previous attempts to age lungfish using a number of techniques have had only limited success. We report on ages obtained from the dense lamellar bone of the scale, which were isolated from the organic layers that thicken and subsequently obscure the 14C signal. Using the characteristics of the bomb curve, 2 parameter von Bertanalffy growth functions were fit, providing an estimate of absolute age to be ∼65–70 yr. The information gleaned from this study will aid in assessing the population structure, and therefore management, of this vulnerable species.

Bamboo corals (Family Isididae) are an important component of seamount benthos south of Tasmania. Besides having lifespans of up to 400 yr, little is known about their basic ecology, nor how to decode potential climate signals encoded in their skeletons. We explored the stable nitrogen isotope and radiocarbon compositions of the skeletal organic fraction of the genera Isidella, Keratoisis and Lepidisis collected from 3 Tasmanian seamounts. Analyses were performed on tissues and organic node growth rings sampled at a temporal resolution of 1 to 4 yr. Radiocarbon chronologies exhibited nuclear bomb signals characteristic of surface waters and constrained radial growth rates to ~35 ± 10 µm yr–1 for 3 specimens of the genus Lepidisis and 113 ± 17 µm yr–1 for 1 specimen of Isidella. δ15N values of the living tissue and underlying gorgonin were similar and averaged 9 to 12‰. Records of δ15N from 8 different specimens showed subtle, quasi-decadal patterns over the last ~100 yr, although the amplitude of these features (~1‰) was similar to the average intra- and intercolony reproducibility. These results demonstrate the utility of deep-sea corals to track seamount biogeochemical processes over long time scales, and suggest that the extent of nutrient depletion of surface waters and associated trophic dynamics have remained relatively constant in this region over centuries. This provides an important baseline for the evaluation of the impacts of anthropogenic climate change.

The Center for AMS, Lawrence Livermore National Laboratory (CAMS) modified high-intensity Cs+ sputter source has several key characteristics, including very high ion current output, that make it useful for AMS applications. Within the AMS community there have been suggestions that certain aspects of operation of a sputter ion source at very high output levels could result in low ionization efficiency and the likelihood of consuming (burning through) small samples without acquiring adequate statistics. This is of particular importance for small mass carbon targets. We have recently re-determined the carbon ionization efficiency of the CAMS sputter source using graphite targets derived from Oxalic Acid I & II and demonstrated relatively high ionization efficiency (∼33%) during the operation of these sources at high output levels. We also examine the relationship between ion source efficiency and sample size.

Coralline sponges have the potential to fill in gaps in our understanding of subsurface oceanographic variability. However, one disadvantage they have compared to hermatypic reef building coral proxies is that they do not have annual density bands and need to be radiometrically dated for an age determination. To elucidate growth rate variability we have measured radiocarbon in 1 mm increments from Astrosclera willeyana sponges collected off the Central and Northern Great Barrier Reef (GBR) and from Truk in the Caroline Islands and compared these radiocarbon profiles to independently dated coral radiocarbon records. Growth rates of the GBR sponges average 1.2 {+-} 0.3 and 1.0 {+-} 0.3 mm yr{sup -1}, north and central respectively but can vary by a factor of two. The growth rate of the Truk sponge averages 1.2 {+-} 0.1 mm yr{sup -1}. These growth rates are significantly faster to those measured for other GBR Astrosclera willeyana sponges (0.2 mm yr{sup -1}) by Calcein staining (Woerheide 1988).

The ability to reliably age siliceous sponges is explored using radiocarbon dating of several hexactinellid sponge specimens including Rossella racovitzae racovitzae Topsent, 1901 (C. Hexactinellida: O. Lyssacinosida: F. Rossellidae), collected from the Ross Sea, Antarctica. The optimal pretreatment was found to consist of both sequential acid digestion and pre-roasting at temperatures >400 °C. Subsequent combustion at 900 °C liberated the proteinaceous material within the spicule matrix and once the reservoir age of the surrounding water was accounted for, a linear extension rate was calculated to be around 2.9 mm yr−1, aging the sponge at ∼440 years old.

Past glacial-interglacial climate transitions were accompanied by millennial-scale pulses in atmospheric CO2 that are widely thought to have resulted from the release of CO2 via the Southern Ocean. However, direct proxy evidence for a Southern Ocean role in regulating past ocean-atmosphere CO2 exchange is scarce. Here we use combined radiocarbon and neodymium isotope measurements from the last deglaciation to confirm greatly enhanced overturning and/or air-sea exchange rates relative to today, in particular during the Bolling-Allerod warm interval. We show that this deglacial pulse in ocean ventilation was not driven by the North Atlantic overturning alone, and must have involved an increase in the ventilation of southern-sourced deep waters. Our results thus confirm the removal of a physical and/or dynamical barrier to effective air-sea (CO2) exchange in the Southern Ocean during deglaciation, and highlight the Antarctic region as a key locus for global climate/carbon-cycle feedbacks.

� 60.5%, and individual samples range from � 72% to 134%. The annual average postbomb maximum occurs in 1973 at 122%. The timing of the postbomb maximum is consistent with a primary subtropical source for the surface waters in the Indonesian seas. During the postbomb period, the coral records regular seasonal cycles of 5% to 20%. Seasonal high D 14 C occur during March–May (warm, low salinity), and low D 14 C occur in September (cool, higher salinity). The D 14 C seasonality is coherent and in phase with the seasonal D 14 C cycle observed in Makassar Strait. We estimate the influence of high D 14 C Makassar Strait (North Pacific) water flowing through the Lombok Strait using a two end-member mixing model and the seasonal extremes observed at the two sites. The percentage of Makassar Strait water varies between 16% and 70%, and between 1955 and 1990, it averages at 40%. The rich D 14 C variability has a biennial component reflecting remote equatorial Indian Ocean forcing and a component in the ENSO band, which is interpreted to reflect Pacific forcing on the D 14 C signature in

We provide geochemical analyses and grain size data for a clearly layered, 80 cm thick sedimentary deposit close to a roof collapse in Blanche Cave near Naracoorte in SE South Australia. This deposit contains aeolian material deposited between ∼40 ka and 14 ka cal BP and which yields airborne sediments spanning the Last Glacial Maximum, a period of time with little information for the Australian continent. The deposit also contains abundant vertebrate fossil material derived from owl pellets, accumulation and pitfall entrapment. Below the studied profile, large vertebrate remains are found but are not discussed here. No Holocene sedimentation occurred at the site examined in the cave, and the top of the sequence is capped with a layer that has been anthropologically disturbed and contains exotic Pinus pollen. Chronologies of the deposit were obtained using two dating techniques: single stage accelerator mass spectrometer (SSAMS) 14C analysis of 23 charcoal samples and optically stimulated luminescence (OSL) dating of quartz from 6 sediment samples. The 14C chronology is preferred to describe the history of the deposits since the OSL chronology, which consistently overestimates the associated radiocarbon dates, may be inaccurate due to complexities in calculating dose rates, and may in addition represent the timing of sediment deposition through the cave opening rather than sediment transport to the deposit site. Morphological analysis of single quartz grains and grain size analysis indicate different provenance that is confirmed through the geochemical analyses of bulk sediment. Major elements were measured by X-ray Fluorescence (XRF), trace and rare earth elements by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA ICP-MS), and Neodymium isotopic ratios were obtained using a Thermal Ionisation Mass Spectrometer (TIMS). Our results indicate that the aeolian material deposited in Blanche Cave over the 40–14 ka cal BP period originated from different sources across South Australia, although Nd isotopes clearly indicate a close association with sediments of the Kanmantoo Group outcropping along the eastern portion of the Mount Lofty Ranges and the Padthaway Ridge further south, both being located to the NW and NNW of the cave. During the latter part of Marine Isotope Stage 3, conditions were wetter and windblown sediment came from the coastal region just north and south of the Coorong Lagoon, with winds originating from the north-northwest. At that time, woody taxa appear to have vegetated the landscape. During the drier phases, especially the Last Glacial Maximum, sediment came from further inland, thus suggesting a different predominant wind direction, more from the northwest. The deglaciation saw material originating from a more northerly direction.

[1] To explore the seasonal to decadal variability in surface water masses that contribute to the Indonesian throughflow, we have generated a 115-year bimonthly coral-based radiocarbon time series from a coral in the Makassar Straits. In the pre-bomb (pre-1955) era from 1890 to 1954, the radiocarbon time series occasionally displays a small seasonal signal (10–15‰). After 1954 the radiocarbon record increases rapidly, in response to the increased atmospheric 14C content caused by nuclear weapons testing. From 1957 to 1986 the record displays clear seasonal variability from 15 to 60‰ and the post-bomb peak (163 per mil) occurred in 1974. The seasonal cycle of radiocarbon can be attributed to variations of surface waters passing through the South Makassar Strait. Southern Makassar is under the influence of the Northwest Monsoon, which is responsible for the high austral summer radiocarbon (North Pacific waters) and the Southeast Monsoon that flushes back a mixture of low (South Pacific and upwelling altered) radiocarbon water from the Banda Sea. The coral record also shows a significant 14C peak in 1955 due to the bomb-14C water advected into this region from nuclear weapons tests in the Marshall Islands in 1954.

[1] Fine particulate matter collected at two urban, four near-urban, and six remote sites throughout the United States were analyzed for total carbon (TC) and radiocarbon (14C). Samples were collected at most sites for both a summer and winter season. The radiocarbon was used to partition the TC into fossil and contemporary fractions. On average, contemporary carbon composed about half of the carbon at the urban, ∼70–97% at near-urban, and 82–100% at remote sites. At Phoenix, Arizona, and Seattle, Washington, one monitor was located within the urban center and one outside to assess the urban excess over background concentrations. During the summer the urban and rural sites had similar contemporary carbon concentrations. However, during the winter the urban sites had more than twice the contemporary carbon measured at the neighboring sites, indicating anthropogenic contributions to the contemporary carbon. The urban fossil carbon was 4–20 times larger than the neighboring rural sites for both seasons. Organic (OC) and elemental carbon (EC) from TOR analysis were available. These and the radiocarbon data were used to estimate characteristic fossil and contemporary EC/TC ratios for the winter and summer seasons. These ratios were applied to carbon data from the Interagency Monitoring of Protected Visual Environments network to estimate the fraction of contemporary carbon at mostly rural sites throughout the United States. In addition, the ratios were used to develop a semiquantitative, lower bound estimate of secondary organic carbon (SOC) contribution to fossil and contemporary carbon. SOC accounted for more than one-third of the fossil and contemporary carbon.

New ΔR values are presented for 10 known-age shells from the Kimberley region of northwest Australia. Previous estimates of ΔR for the Kimberley region are based on only 6 individual shell specimens with dates of live collection known only to within 50 yr (Bowman 1985a). Here, we describe the results of our recent attempts to constrain ΔR variability for this region by dating a suite of known-age pre-AD 1950 shell samples from the Australian Museum and Museum Victoria. A regional ΔR of 58 ± 1714C yr for open waters between Broome and Cape Leveque is recommended based on 7 of these specimens. The criteria used to select shells for dating and inclusion in the regional mean are discussed.

Like elsewhere in Australia, the archaeology of northwest Queensland has focused on the antiquity of occupation and the continuity of that occupation through the Last Glacial Maximum (LGM), in an attempt to better understand the adaptive capabilities and strategies of early humans. Veth (1989, 1993) has hypothesised that the northwest Queensland savannah, as an important ‘corridor’ for the colonisation of Australia (e.g. Bird et al. 2005; Horton 1981), should contain ‘early’ sites; and furthermore that with the climatic deterioration associated with the LGM, such sites should fit one of two patterns: (1) they will be abandoned and display a cultural hiatus; or, (2) if located in resource-rich zones within catchments (‘local refuges’), they will continue to be utilised, though subsistence strategies will be modified to rely more heavily on locally available resources. The northwest Queensland sites of Colless Creek at Lawn Hill (Hiscock 1984, 1988), and GRE8 near Riversleigh (Slack 2007:218-251; Slack et al. 2004), both fit the second pattern, i.e. persistent occupation through the LGM with altered strategies to cope with increased aridity. However, outside these local refugia, sites pre-dating the LGM have not yet been located in the northwest Queensland savannah. For example, Mickey Springs 34 (Porcupine Gorge) provides evidence for human occupation from c.10,000 BP (Morwood 1990, 1992, 2002) and Cuckadoo Shelter in the Selwyn Ranges (Davidson et al. 1993) provides a near basal date of 15,270}210 BP; Veth (1989:87) argued that such sites reflect the post-LGM expansion of groups from refuges. The evidence available to date raises the question as to whether the wider northwest Queensland savannah corridor was indeed occupied in the pre-LGM period, when rainfall levels were higher and there was greater availability of surface water and food resources (cf. Hiscock and Wallis 2005).

In 2008, we began two related research projects that focus on recent Australian rock art, made after the arrival of Asians and Europeans, in part of northwest Arnhem Land's Wellington Range. This area has extensive and diverse rock art, including many examples of paintings that reflect contact between local Aboriginal people and visitors to their shores. At some sites figures made of beeswax are found superimposed under and over paintings, thus providing a means of obtaining minimum and maximum ages for pigment art. We report on the results of an initial radiocarbon beeswax dating programme at the Djulirri site complex. Results include the earliest age for a depiction of a Southeast Asian watercraft in Australian rock art, which is also Australia's earliest contact period rock art depiction discovered so far. Based on the probability distribution of the calibrated ages, it is 99.7% probable this image dates to before AD 1664 and likely is much older. The significance of this result is discussed in relation to early contact history, as revealed by historic documents and archaeological excavation. Other important results suggest a close encounter between local Aboriginal people and Europeans occurred in the 1700s, before British exploration and settlement in the Arnhem Land region.

We present the first radiocarbon dates from previously unrecorded, secondary burials in the Cardamom Mountains, Cambodia. The mortuary ritual incorporates nautical tradeware ceramic jars and log coffins fashioned from locally harvested trees as burial containers, which were set out on exposed rock ledges at 10 sites in the eastern Cardamom Massif. The suite of 28 14C ages from 4 of these sites (Khnorng Sroal, Phnom Pel, Damnak Samdech, and Khnang Tathan) provides the first estimation of the overall time depth of the practice. The most reliable calendar date ranges from the 4 sites reveals a highland burial ritual unrelated to lowland Khmer culture that was practiced from cal AD 1395 to 1650. The time period is concurrent with the 15th century decline of Angkor as the capital of the Khmer kingdom and its demise about AD 1432, and the subsequent shift of power to new Mekong trade ports such as Phnom Penh, Udong, and Lovek. We discuss the Cardamom ritual relative to known funerary rituals of the pre- to post-Angkorian periods, and to similar exposed jar and coffin burial rituals in Mainland and Island Southeast Asia.

This paper presents the initial radiocarbon ages from the Lower Murray Archaeological Project developed in conjunction with the Ngarrindjeri Heritage Committee in South Australia. As part of this community based research program, a total of 59 shell (V. ambiguus) and charcoal samples were selected for radiocarbon dating. Radiocarbon ages varied significantly between sites within the region and ranged from 150-490 calBP at Pomberuk (Hume Reserve Midden and Historic Campsite) to 8190-8390 calBP at Glen Lossie Midden and Burial Site (GLMBS). These results will contribute to developing a more comprehensive understanding of human occupation in Ngarrindjeri ruwe (lands and waters) and assist in developing a local chronology for the region. In the last decade there has been growing concern from the Ngarrindjeri community regarding investigations on burials and invasive analysis of skeletal remains during a period when community priorities have involved the repatriation of Old People's remains from museums and university departments (Wilson 2005; Hemming and Wilson 2010). As a result, this has shifted archaeological investigations within Ngarrindjeri ruwe (lands and waters), enabling new research opportunities to be developed that focus on research that contributes to the strategic goals of the community. These projects are integrated within broader cultural heritage management agendas driven by the Ngarrindjeri Heritage Committee (NHC) who engage university researchers and students to work on projects that are beneficial to the broader community. In 2007, the NHC engaged Wilson to undertake archaeological investigations on shell midden sites in the Lower Murray following cultural heritage surveys conducted by Australian Cultural Heritage Management (ACHM) during the Lower Murray Reclaimed Irrigation Area (LMRIA) Project. The NHC were particularly interested in questions surrounding the long-term chronology of significant cultural places in the Lower Murray as well as evidence for the continuity of occupation. An extensive dating program was undertaken as a component of Wilson's doctoral research (under the auspices of the Lower Murray Archaeological Project, hereafter LMAP) to: establish the minimum age of shell midden sites across the study region; develop a chronology for occupation at specific shell midden sites; and, establish a cultural sequence for open sites. This paper reports on the initial radiocarbon ages obtained from surface sampling and excavations conducted for LMAP and examines the implications for understanding the archaeology of the Lower Murray. These results provide new evidence for human occupation in Ngarrindjeri ruwe during the Holocene that spans ca 8400 calBP to the present. Study region The study region is situated within Ngarrindjeri ruwe--the traditional lands and waters of the Indigenous people stretching across the Lower Murray River, Lakes and Coorong in South Australia. The Lower Murray River is part of the Murray-Darling Basin (or riverine plain) which is Australia's largest river that flows from Mt Kosciusko northwest through New South Wales and Victoria before entering the terminal lake system which includes Lake Alexandrina, Lake Albert and the Coorong at the river mouth in South Australia. It forms part of a Wetland of International Importance under the Ramsar Convention and supports an extensive range of native flora and fauna--most of which are under threat by irrigation, development and regulation of river flows. Archaeological investigations were conducted between the townships of Mypolonga and Montieth (Figure 1). A total of six shell midden sites were excavated: Glen Lossie Midden and Burial Site (GLMBS); Glen Lossie Midden 6 (GLM6); Glen Lossie Midden 5 (GLM5); Glen Lossie Midden 3 (GLM3); Pomberuk (Hume Reserve Midden and Historic Campsite) (POM); and Swanport Midden 1 (SWM1). Sturt Reserve Midden and Montieth Midden 1 were also identified by the NHC as significant places to excavate, however it was decided that these two complexes would be incorporated into future investigations. …