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The Wellington Caves were the first Australian locality from which Europeans collected and analysed vertebrate fossils. Within this system, Cathedral Cave contains Australia's stratigraphically deepest sequence of fossil‐bearing infill sediments, the age and depositional history of which has been poorly understood. Here we present results from a new excavation of the upper 4.2 m of the deposit, reanalysing the stratigraphy, petrography, sedimentology and geochemistry, and employing optically stimulated luminescence dating, radiocarbon dating and Bayesian age modelling to establish a robust chronology. We recognise 13 sedimentary layers and sublayers in two stratigraphic units. Unit 2 accumulated between 72 000 ± 5000 and 38 000 ± 7000 years ago as sediments and animals entered through a now‐blocked ceiling hole. Accumulation halted for around 30 000 years when the hole closed. Unit 1 accumulated when deposition was reinitiated around 7000 ± 2000 years ago, continuing through to a few hundred years ago. Our chronology refutes earlier dating of the deposit, which suggested that extinct Pleistocene megafauna taxa persisted locally until the Last Glacial Maximum. It confirms the deposit as one of the few in Australia that formed during the interval of major environmental upheaval marked by the arrival of humans, variable climate and the extinction of many megafaunal species. [ABSTRACT FROM AUTHOR]

Climate change is affecting the distribution of species and the functioning of ecosystems. For species that are slow growing and poorly dispersed, climate change can force a lag between the distributions of species and the geographic distributions of their climatic envelopes, exposing species to the risk of extinction. Climate also governs the resilience of species and ecosystems to disturbance, such as wildfire. Here we use species distribution modelling and palaeoecology to assess and test the impact of vegetation–climate disequilibrium on the resilience of an endangered fire‐sensitive rainforest community to fires. First, we modelled the probability of occurrence of Athrotaxis spp. and Nothofagus gunnii rainforest in Tasmania (hereon "montane rainforest") as a function of climate. We then analysed three pollen and charcoal records spanning the last 7,500 cal year BP from within both high (n = 1) and low (n = 2) probability of occurrence areas. Our study indicates that climatic change between 3,000 and 4,000 cal year bp induced a disequilibrium between montane rainforests and climate that drove a loss of resilience of these communities. Current and future climate change are likely to shift the geographic distribution of the climatic envelopes of this plant community further, suggesting that current high‐resilience locations will face a reduction in resilience. Coupled with the forecast of increasing fire activity in southern temperate regions, this heralds a significant threat to this and other slow growing, poorly dispersed and fire sensitive forest systems that are common in the southern mid to high latitudes. [ABSTRACT FROM AUTHOR]

The use of 14C to elucidate sources of carbon within freshwater aquatic ecosystems is challenging the assumption that modern autochthonous carbon dominates energy flows. We measured the uptake of old carbon through several trophic levels of a wetland fed by groundwater of the Great Artesian Basin, Australia, the largest artesian basin in the world. Stable isotopes (δ13C and δ15N) and radiocarbon (14C) were used to quantify food chain links and connection between groundwater and surface water food webs. Our results suggest that old groundwater was the dominant carbon source even at the highest trophic levels, with predatory fish returning apparent carbon ages of up to 11 ka. Stable isotope analysis (δ13C and δ15N) identified trophic links between fish, aquatic insects, and algae with smaller contributions from particulate organic matter to the food webs. As natural mound springs and associated wetlands are the only source of reliable water during dry periods over vast areas of the western Great Artesian Basin, the result has potential implications for the interpretation of archaeological artifacts associated with indigenous passage within the interior. [ABSTRACT FROM AUTHOR]

Abstract: Aim: To assess whether climate directly influences aquatic ecosystem dynamics in the temperate landscape of Tasmania or whether the effects of long‐term climatic change are mediated through the terrestrial environment (indirect climate influence). Location: Paddy's Lake is located at 1065 m a.s.l. in temperate north‐west Tasmania, a continental island south‐east of mainland Australia (41°15–43°25′ S; 145°00–148°15′ E). Methods: We developed a new 13,400 year (13.4 kyr) palaeoecological dataset of lake sediment subfossil cladocerans (aquatic grazers), bulk organic sediment carbon (C%) and nitrogen (N%) and δ13C and δ15N stable isotopes. Comparison of this new data was made with a recently published pollen, geochemistry and charcoal records from Paddy's Lake. Results: Low cladoceran diversity at Paddy's Lake is consistent with other temperate Southern Hemisphere lakes. The bulk sediment δ15N values demonstrate a significant lagged negative response to pollen accumulation rate (pollen AR). Compositional shifts of dominant cladoceran taxa (Bosmina meridionalis and Alona guttata) occur following changes in both pollen AR and pollen (vegetation) composition throughout the 13.4 kyr record at Paddy's Lake. The δ15N values demonstrate a significant positive lagged relationship to the oligotrophic:eutrophic cladoceran ratio. Main conclusions: Long‐term changes in cladoceran composition lag changes in both pollen AR and terrestrial vegetation composition. We interpret pollen AR as reflecting climate‐driven changes in terrestrial vegetation productivity and conclude that climate‐driven shifts in vegetation are the principal driver of the cladoceran community during the last ca. 13.4 kyr. The significant negative lagged relationship between pollen AR and δ15N reflects the primary control of vegetation productivity over within‐lake nutrient status. Thus, we conclude that the effects of long‐term climate change on aquatic ecosystem dynamics at our site are indirect and mediated by the terrestrial environment. Vegetation productivity controls organic soil development and has a direct influence over lake trophic status via changes in the delivery of terrestrial organic matter into the lake. [ABSTRACT FROM AUTHOR]

Aim To test competing hypotheses about the timing and extent of Holocene landscape opening using pollen-based quantitative land-cover estimates. Location Dove Lake, Tasmanian Wilderness World Heritage Area, Australia. Methods Fossil pollen data were incorporated into pollen dispersal models and corrected for differences in pollen productivity among key plant taxa. Mechanistic models ( REVEALS-Regional Estimates of VEgetation Abundance from Large Sites) employing different models for pollen dispersal (Gaussian plume and Lagrangian stochastic models) were evaluated and applied in the Southern Hemisphere for the first time. Results Validation of the REVEALS model with vegetation cover data suggests an overall better performance of the Lagrangian stochastic model. Regional land-cover estimates for forest and non-forest plant taxa show persistent landscape openness throughout the Holocene (average landscape openness ~50%). Gymnoschoenus sphaerocephalus, an indicator of moorland vegetation, shows higher values during the early Holocene (11.7-9 ka) and declines slightly through the mid-Holocene (9-4.5 ka) during a phase of partial landscape afforestation. Rain forest cover reduced (from ~40% to ~20%) during the period between 4.2-3.5 ka. Main conclusions Pollen percentages severely under-represent landscape openness in western Tasmania and this bias has fostered an over-estimation of Holocene forest cover from pollen data. Treeless vegetation dominated Holocene landscapes of the Dove Lake area, allowing us to reject models of landscape evolution that invoke late-Holocene replacement of a rain forest-dominated landscape by moorland. Instead, we confirm a model of Late Pleistocene inheritance of open vegetation. Rapid forest decline occurred after c. 4 ka, likely in response to regional moisture decline. [ABSTRACT FROM AUTHOR]

ABSTRACT Palynomorphs from the ODP Site 820 marine core have provided a detailed record of terrestrial environmental responses to glacial-interglacial forcing over the last 250 000 years in the Australian Wet Tropics. The development of an accurate geochronological framework for this key sequence has proved challenging. Consequently, different dominant forcing mechanism(s) have been proposed to drive environmental change in the low latitudes. A new chronology for the last 60 000 years, based on accelerator mass spectrometry radiocarbon (14C) dates of pollen concentrate material and the existing Marine Isotope Stage boundaries (MIS 4 to 1) has been produced. This new chronology provides a robust geochronological framework for interpreting environmental records across the region. In particular, our age model helps to resolve several debates concerning the timing of climatic changes and their impacts on both the marine and the terrestrial systems, as well as possible human arrival and associated impacts on the region's ecosystems. Our findings suggest 14C dating of terrestrial pollen concentrate in marine sediments is a valuable tool for resolving major chronological uncertainties in potentially diagenetically altered marine CaCO3 sediments and should play a role in future multi-dating strategies. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

In the absence of eyewitness reports or clear sedimentary structures, it can be difficult to interpret tsunami deposits or reconstruct tsunami inundation patterns. The emplacement dynamics of two historical tsunami deposits were investigated at seven transects in Okains Bay, New Zealand, using a combined geospatial, geomagnetic and sedimentological approach. The tsunami deposits are present as layers of sand and silt intercalated between soils and become finer and thinner with distance inland. The deposits are attributed to the 1960 and possibly the 1868 tsunamis, based on radiometric dating and correlation with historical records. Measurements of Magnetic Fabric (MF: Anisotropy of Magnetic Susceptibility) and particle size were used to reconstruct the evolution of flow dynamics laterally and vertically. A combination of statistical methods, including spatial autocorrelation testing, Spearman's rank order correlation, Principal Component Analysis (PCA) and K-means cluster analysis, was applied to examine relationships between MF parameters and sediment texture, and infer depositional hydrodynamics. Flow patterns deduced from MF show the estuary channel acted as a conduit for inundation, with flow commonly aligned sub-perpendicular to the estuary bed. MF and sediment data suggest deposition occurred from settling during laminar flow. Evidence of both uprush and backwash deposition, as well as wave reflection from infrastructure, was found. Statistical analysis of data showed significant relationships between grain size parameters and MF parameters associated with flow speed and magnetic fabric type. PCA and cluster analysis differentiated samples into two primary hydrodynamic groups: (1) samples deposited from laminar flow; and (2) samples deposited close to the limit of inundation, which includes samples deposited further inland, those affected by flow convergence, and those in the upper part of tsunami deposits. This approach has potential as a tool for reconstructing hydrodynamic conditions for palaeotsunamis and by combining spatial and statistical analyses, large-scale investigations can be more easily performed. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

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In 1989-1990, part of a wooden artefact with an incised criss-cross design was recovered from the pre- Lapita pottery level of the U- L- T area of the Apalo site in the Arawe Islands of New Britain, Papua New Guinea. The artefact was made from a Ficus tree species, and has been dated by AMS to 4043-3848 calBP (95.4%). This makes it the oldest directly dated ornamented object in the New Guinea region, though zoomorphic stone figurines and pestles and decorated stone mortars of the region are probably of similar antiquity. The artefact adds to the growing body of information about people in the Papua New Guinea Islands prior to the appearance of Lapita pottery, though the simplicity of the design and its widespread distribution in time and space caution against seeing it as a precursor to the Lapita design system. The nature of the original artefact is uncertain. [ABSTRACT FROM AUTHOR]

ABSTRACT It is widely accepted that most larger Australian vertebrates were extinct by 40 ka. The reliability of <20-ka radiocarbon (14C) ages on charcoal stratigraphically associated with sthenurine (short-faced) kangaroo tooth fragments from Seton Rockshelter, Kangaroo Island, have therefore proven contentious. Some researchers have argued these fossils were in situ, while others have claimed they were reworked. To address this we obtained new 14C ages on bones from the site. These bone ages are not only consistent with earlier charcoal ages, but are in near-perfect stratigraphic order, providing strong support for the site's stratigraphic integrity. Our analyses indicate units aged 21−17 ka were primarily accumulated by Tasmanian devils ( Sarcophilus harrisii) and owls ( Tyto species), after which humans became the primary accumulation agent. The tight chronology, faunal trends and current lack of evidence for older layers from which specimens could have been reworked suggest the sthenurine remains may be in situ. However, because attempts to directly date sthenurine material failed, we cannot confidently assert that they survived to this time. Therefore, Seton Rockshelter may be best excluded from the Pleistocene extinction debate until the site can be re-excavated and more conclusive evidence collected, including more complete or directly datable sthenurine remains. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Two fluvial sediment cores taken from a floodplain of the Hawkesbury- Nepean River system in the Sydney region, eastern Australia are dated using Optically Stimulated Luminescence ( OSL) to provide a reliable chronology essential for the management and planning of water resources. Nine charcoal 14 C ( AMS) dates constrain these OSL ages. Quartz extracted from seven OSL samples from each of the cores was measured using both single-grain and multi-grain OSL techniques. Three of the single-grain natural dose distributions appear to be well bleached, but the others appear to be incompletely bleached to various degrees. Three minimum-age models ( MAM, MAMUL and IEU) are applied to the single-grain dose distributions. We conclude that these models give consistent age estimates. For one of the cores it appears to be necessary to use a minimum-age model to obtain accurate ages, but in the other core incomplete bleaching is probably less important than postdepositional mixing and mixing during sampling. As a result, the burial age is probably best estimated using the weighted average of the individual single-grain dose estimates. The application of multi-grain OSL techniques to these samples results in an average apparent age overestimation of ∼200 years, which is significant for these samples, but negligible for sediments older than a few thousand years. The intention is that the chronology obtained in this study will be used in conjunction with a proxy flood record, derived from floodplain sediments, to gain an understanding of the long-term variability in periods of high and low rainfall in eastern Australia. [ABSTRACT FROM AUTHOR]

Chronological, sedimentological and geochemical analyses of a clastic infill from Kelly Hill Cave ( 5K1), Kangaroo Island, document a palaeoenvironmental record that spans from the Late Pleistocene to the middle Holocene. We AMS radiocarbon-dated bone collagen and U- Th-dated speleothem to determine that fossiliferous sediments were deposited between >20 ka and 7 ka ago. Most of the 15 sedimentary layers are dominated by sand- and silt-sized quartz that is physically and geochemically comparable with surface soils in the Kelly Hill area. Late Pleistocene and Last Glacial Maximum strata are represented primarily by homogeneous, poorly sorted quartz-rich sediments that contain little organic matter, but include a thin layer composed largely of silt-sized clay pellets that resemble sediments deflated from playa lakes. Microstructures observed in petrographic slides indicate that, with the exception of one layer, all sediments experienced little reworking once deposited in the cave. Some layers display pedogenic microstructures such as redeposited clays and opaline silica infilling that indicate postdepositional modification; that is, cave-floor soil development. Overlying Holocene-aged sediments also consist mainly of quartz but have much greater organic matter content. Some of these sediments have been strongly influenced by re-precipitated organic matter that appears to have been transported into the cave via vadose drip water. The presence of dissolved organic matter in soil/vadose waters suggests a high vegetation density and acidic soils, which are congruent with the more equitable climatic conditions characteristic of the Holocene. The sediments described here provide a valuable palaeoenvironmental record that will facilitate future interpretation of associated vertebrate fossils. [ABSTRACT FROM AUTHOR]

Bog peat soils have been accumulating at Wellington Plain peatland, Victoria, Australia for the last 3300 years. Now, dried peat soils are common adjacent to bog peats. The 14C basal age of dried peat is not different from the 14C basal age of bog peat, which supports the theory that dried peat formed from bog peat. A novel application of 210Pb dating links the timing of this change with the introduction of livestock to Wellington Plain in the mid-1800s. Physical loss of material appears to have been the dominant process removing material as bog peats drained to form dried peats, as indicated by the mass balances of carbon and lead. This research has implications for the post-fire and post-grazing restoration of bogs in Victoria's Alpine National Park, and the contribution of peat soils to Australia's carbon emissions. [ABSTRACT FROM AUTHOR]

We report carbon isotope measurements on pre-bomb museum samples of freshwater mussel shells collected alive from riverine locations in New South Wales, Australia. The calculated reservoir ages, ranging from -60 to +112 years, are much smaller than those for Australian marine shells and not considered significant for the radiocarbon dating of Late Pleistocene freshwater shells from the Murray-Darling Basin. [ABSTRACT FROM AUTHOR]