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The Willandra Lakes in semi-arid southeastern Australia provide some of the most continuous combined palaeoenvironmental and archaeological records on the continent. These are best preserved within the transverse shoreline (lunette) dunes on their downwind margins. Following final lake retreat c. 15 ka avulsion of the dominant fluvial inflow eastwards, the Willandra lunettes periodically reactivated, experiencing erosion, aeolian redeposition and alluvial sheetwash. These reworked sedimentary archives reflect regional climatic conditions rather than those of the entire catchment. Yet the focus of most study in the region to date has remained on the late Pleistocene. The general paucity of Holocene data has contributed to a perception that people largely abandoned the area in favour of the perennial Murray and Darling Rivers to the south and west. Our study reconstructs past geomorphological conditions and patterns of human mobility in adjacent Lakes Mungo and Durthong over the last c. 15 ka subsequent to final lake retreat, including the most recent 150 years since Europeans established pastoralism in the region. Our data show that Indigenous people did not abandon the area as previously assumed, but developed effective strategies for responding to the changed environmental conditions. Final lake retreat transitioned into a phase of aeolian accumulation c. 15–12 ka, indicating locally dry conditions. Subsequent aeolian reactivation peaked during arid phases experiencing less rainfall in the early Holocene and twice in the most recent 1000 years prior to European settlement in the area. Alluvial sheetwash was deposited onto lake floors during the mid-Holocene, and again in the early decades of European settlement. Aeolian reactivation, likely driven by European pastoral activities, increases in the most recent 150 years. Our study underscores the necessity of integrating geomorphological and archaeological investigations over landscape scales in order to optimise our understanding of interactions between people and their environment through time. [ABSTRACT FROM AUTHOR]

Climatic forcing of fluvial systems has been a pre-occupation of geomorphological studies in Australia since the 1940s. In the Riverine Plain, southeastern Australia, the stable tectonic setting and absence of glaciation have combined to produce sediment loads that are amongst the lowest in the world. Surficial sediments and landforms exceed 140,000 yr in age, and geomorphological change recorded in the fluvial, fluvio-lacustrine and aeolian features have provided a well-studied record of Quaternary environmental change over the last glacial cycle. The region includes the Willandra Lakes, whose distinctive lunette lakes preserve a history of water-level variations and ecological change that is the cornerstone of Australian Quaternary chronostratigraphy. The lunette sediments also contain an ancient record of human occupation that includes the earliest human fossils yet found on the Australian continent. To date, the lake-level and palaeochannel records in the Lachlan-Willandra system have not been fully integrated, making it difficult to establish the regional significance of hydrological change. Here, we compare the Willandra Lakes environmental record with the morphology and location of fluvial systems in the lower Lachlan. An ancient channel belt of the Lachlan, Willandra Creek, acted as the main feeder channel to Willandra Lakes before channel avulsion caused the lakes to dry out in the late Pleistocene. Electromagnetic surveys, geomorphological and sedimentary evidence are used to reconstruct the evolution of the first new channel belt following the avulsion. Single grain optical dating of floodplain sediments indicates that sedimentation in the new Middle Billabong Palaeochannel had commenced before 18.4 ± 1.1 ka. A second avulsion shifted its upper reaches to the location of the present Lachlan River by 16.2 ± 0.9 ka. The timing of these events is consistent with palaeohydrological records reconstructed from Willandra Lakes and with the record of palaeochannels on the Lachlan River upstream. Willandra Lakes shows high inflows during the Last Glacial Maximum (∼22 ka), but their subsequent drying between 20.5 ka and 19 ka was caused by river avulsion rather than regional aridity. This case study highlights the benefits of combining fluvial with lacustrine archives to build complementary records of hydrological change in lowland riverine plains. [ABSTRACT FROM AUTHOR]

Three freshwater mussel shell tools recovered from the Lake Mungo lunette, in semi-arid south-eastern Australia with bracketing age estimates of 40–30 ka, and a possible fourth tool with bracketing age estimates of 50–40 ka, are described. An experimental approach, combined with detailed structural and taphonomic analysis of the shell establishes the presence of both deliberate cultural modification and wear traces from use on the mussel fragments. The characterization of Australian Pleistocene stone artefacts as being simple and unchanging is steadily being challenged through recent studies of Pleistocene assemblages from Lake Mungo and elsewhere, and these early shell tools reinforce the multidimensionality of ancient Australian technologies. [ABSTRACT FROM AUTHOR]

Abstract: Lake Mungo, presently a dry lake in the semi-arid zone of southeastern Australia, preserves a unique record of human settlement and past environmental change within the transverse lunette that built up on its downwind margin. The lunette is >30 km long and the variable morphology along its length suggests spatial variability in deposition over time. Consequently this presents differential potential for the preservation of past activity traces of different ages along the lunette. Earlier work at Lake Mungo focused primarily on the southern section of the lunette, where two ritual burials of considerable antiquity were found. Here we describe the depositional history of the central section of the Lake Mungo lunette, together with the first single grain optically stimulated luminescence (OSL) chronology of the full stratigraphic sequence and of three hearths. We thereby lay the foundation for systematic investigation of the distribution of archaeological traces through the sedimentary record. The older depositional units (Lower and Upper Mungo) were deposited ca. 50–40 ka and ∼34 ka respectively, and are substantially thinner in the central section of the lunette compared with the south. By contrast, the overlying unit of interbedded sands and clayey sands (Arumpo–Zanci units), deposited ca. 25–14 ka, is markedly thicker and dominates the stratigraphic sequence in the central portion of the lunette. Although the sequence broadly reflects previous models of the lunette's depositional history and changing hydrological conditions, our results indicate spatially variable deposition of sediments, possibly as a result of changes in prevailing wind regimes. Archaeological traces are exposed in all stratigraphic units deposited after ca. 50 ka, including sediments deposited after the final lake drying ca. 15 ka, indicating human occupation of the area under a range of palaeoenvironmental conditions. Dating and stratigraphical examination of individual hearth features demonstrates that even within individual stratigraphic units, human occupation persisted under variable conditions. Mid-Holocene occupation of the area following the final lake retreat took place during a period of relatively humid climate. [Copyright &y& Elsevier]

Single-grain optical dating has been widely used to estimate depositional ages for Quaternary sediments. An understanding of the sources influencing the dispersion of equivalent dose (D e) estimates from individual grain measurements is essential for accurate age determination. Beta microdosimetry (i.e., beta dose deposition at the sub-millimetre scale) is a known cause of spread in single-grain D e values, so the detection and assessment of beta dose rate ( D ˙ β) variation is important to properly interpret these data. Here we demonstrate the application of Timepix, a pixelated detector that directly measures in situ beta emissions based on cluster analysis, to determine the beta microdosimetry of natural sediment samples from a cave deposit in Russia and a sand dune in Australia. We describe a Timepix measurement and data processing procedure for natural sediments, and establish sample-specific calibration curves using associated sample radioelement concentrations to convert Timepix count rates into estimates of D ˙ β. On the basis of the Timepix analysis, a 2D 'heat map' of D ˙ β at sub-millimetre resolution was obtained for each sample. Our results show that the D ˙ β estimates are heterogeneous and their non-uniformity gives rise to 9 ± 4 to 26 ± 5% overdispersion in the single-grain D e distributions for the samples examined here. We discuss the likely sources of D ˙ β heterogeneity, based on micromorphological investigations of these sediment samples, which include a variety of materials present in natural deposits associated with D ˙ β 'hot' and 'cold' spots. A comparison of the D ˙ β dispersion with that of the corresponding single-grain D e values shows that the scatter among the latter can be fully or partly explained by beta microdosimetry and other known sources of overdispersion. • Timepix pixelated detector used to measure beta dose rates of natural sediments. • Measurement and data analysis procedure proposed and tested on four samples. • Spatially-resolved 'heat map' of beta dose rates obtained at sub-millimetre resolution. • Beta heterogeneity gives rise to ∼9–26% overdispersion of single-grain D e values. • Beta heterogeneity can fully or partly explain overdispersion of single-grain D e values. [ABSTRACT FROM AUTHOR]

The article discusses the study on establishing a theory of geological heritage and redemptive or recuperative power of material remains of the past of the rivers and elevated mountain ranges in Australia. Three areas in the country which include Adelaide's Hallett Cove, Lake Callabonna Fossil Reserve, and Willandra Lake are considered a geological significance, but had been previously described as wasteland, unproductive, and degraded. Geological perspectives had developed a new lexicon for the appreciation of Australian landscapes to adopt the aesthetics agenda of heritage rhetoric.

Recent success in the amplification of ancient DNA (aDNA) from fossil humans has led to calls for further tests to be carried out on similar material. However, there has been little systematic research on the survival of DNA in the fossil record, even though the environment of the fossil is known to be of paramount importance for the survival of biomolecules over archaeological and geological timescales. A better understanding of aDNA survival would enable research to focus on material with greater chances of successful amplification, thus preventing the unnecessary loss of material and valuable researcher time. We argue that the thermal history of a fossil is a key parameter for the survival of biomolecules. The thermal history of a number of northwest European Neanderthal cave sites is reconstructed here and they are ranked in terms of the relative likelihood of aDNA survival at the sites, under the assumption that DNA depurination is the principal mechanism of degradation. The claims of aDNA amplification from material found at Lake Mungo, Australia, are also considered in the light of the thermal history of this site. [Copyright &y& Elsevier]

Smith's Comment on our functional analysis of grinding stone fragments from Pleistocene contexts at Lake Mungo () draws attention to the low frequency of implements, uncertainties about functional interpretations and archaeological implications. He argues that Pleistocene seed exploitation at Lake Mungo was limited and probably not indicative of a seed grinding economy. We suggest that it is premature to speculate about the scale of seed grinding at Lake Mungo. We also use new data to address concerns raised about our methodology. [ABSTRACT FROM AUTHOR]

Lake Mungo is a currently dry lake basin in the semi-arid zone of southeastern Australia. The transverse dune system on the downwind side contains a record of human occupation of international importance. It also contains one of the most continuous records of climate change over the last glacial cycle in the Australia desert. In this paper we provide a framework for the interpretation of lake level history from before the arrival of people (>41 ka) until after the establishment of the pastoral industry in the area. We present 83 optically stimulated luminescence ages from the Lake Mungo lunette. The lake level history is reconstructed from 34 stratigraphic sections along three transects through the lunette. The dating reveals considerable lake level fluctuations through time which occur over a depth range of ∼10 m in the basin. At its height, probably at multiple times before 20 ka, the lake held more than 1 km3 of water and at its final level at ∼19 ka, contained only 0.03 km3. The inception of Lake Mungo appears to have taken place during the mid-Pleistocene between ∼256 and 369 ka. During the last glacial cycle, Lake Mungo was almost continuously wetter than present from shortly after 60 ka until ∼19 ka. The Upper Mungo, Arumpo and Zanci units represent a succession of lake filling and drying events, briefly interspersed by soils. The final Zanci unit does not represent a single high lake phase, but an initial lake filling followed by a series of short-lived lake level events within a brief period of a few thousand years. At the conclusion of this event, the lake remained dry until the present day. Four OSL ages from a linear dune upwind of Lake Mungo indicates regional aeolian activity from ∼30 ka until present. Widespread erosion that produces the characteristic topography of the lunette began after the arrival of British pastoralists and traditional aboriginal ways of life overlapped briefly with this erosion. The presence of water in Lake Mungo closely corresponds to periods when regional surface temperature was colder than present during the late Pleistocene. Our new data supports a model that decreased evaporation and increased runoff were primarily responsible for increased availability of surface water in the hydrological cycle. • The lake level history of Lake Mungo is reconstructed from 34 stratigraphic sections and 83 luminescence ages. • The lake level fluctuated over a depth range of ∼10 m in the basin, from more than 1 km3 of water to only 0.03 km3. • The inception of the lake appears to have taken place during the mid-Pleistocene at ∼256–369 ka. • The lake filled during the last glacial maximum. • The presence of water in Lake Mungo corresponds to when regional surface temperature was significantly colder than present. [ABSTRACT FROM AUTHOR]

ABSTRACT Fullagar et al. () use microwear and residues to argue for seed grinding in the late Pleistocene at Lake Mungo. The ten Zanci/ Arumpo grindstone fragments in their study represent only three grindstones when conjoined. Grindstones appear to be rare in these assemblages and are small, hand-sized implements. Traces of starch are low, of uncertain taphonomy and not from known economic taxa. The use-polish may indicate grinding of seeds, but these grindstones were used differently to ethnohistorical seed-grinders. Even if seeds were used, this was probably not a seed-based economy. [ABSTRACT FROM AUTHOR]