Rose Whitau

The manipulation of fire is a technological act. The identification of the archaeological signatures of the controlled use of fire has important implications not only for the estimations of the origins and functions of the first fireplaces but also for our understanding of prehistoric technological development and resource use. At Riwi (Kimberley region, Western Australia), excavations over two field seasons have revealed a discontinuous occupation sequence over the past 45 ka, showing numerous, different combustion features interspersed within the deposit. Anthracological and micromorphological investigations at Riwi Cave indicate that the combustion features at the site can be categorised into three types: flat combustion features (type A), dug combustion features (type B) and thick accumulations of mixed combustion residues (type C). These provide evidence for two kinds of combustion practice: (i) fires lit directly on the ground and most likely not re-used and (ii) ground ovens, the latter appearing some 10,000 years after the first evidence for occupation of the site. A comparison of the wood species identified within these combustion features with those from equivalent scattered context levels, enables an exploration of the potential factors influencing wood selection and fire use through time at the site. A detailed J Archaeol Method Theory https://doi.

An extensive series of 44 radiocarbon (14 C) and 37 optically stimulated luminescence (OSL) ages have been obtained from the site of Riwi, south central Kimberley (NW Austra-lia). As one of the earliest known Pleistocene sites in Australia, with archaeologically sterile sediment beneath deposits containing occupation, the chronology of the site is important in renewed debates surrounding the colonization of Sahul. Charcoal is preserved throughout the sequence and within multiple discrete hearth features. Prior to 14 C dating, charcoal has been pretreated with both acid-base-acid (ABA) and acid base oxidation-stepped combustion (ABOx-SC) methods at multiple laboratories. Ages are consistent between laboratories and also between the two pretreatment methods, suggesting that contamination is easily removed from charcoal at Riwi and the Pleistocene ages are likely to be accurate. Whilst some charcoal samples recovered from outside hearth features are identified as outliers within a Bayesian model, all ages on charcoal within hearth features are consistent with stratigraphy. OSL dating has been undertaken using single quartz grains from the sandy matrix. The majority of samples show D e distributions that are well-bleached but that also include evidence for mixing as a result of post-depositional bioturbation of the sediment. The results of the two techniques are compared and evaluated within a Bayesian model. Consistency between the two methods is good, and we demonstrate human occupation at this site from 46.4–44.6 cal kBP (95.4% probability range). Importantly, the lowest archaeological horizon at Riwi is underlain by sterile sediments which have been dated by OSL making it possible to demonstrate the absence of human occupation for between 0.9–5.2 ka (68.2% probability range) prior to occupation.

Wood charcoals excavated from archaeological sites provide a useful tool for palaeoenvironmental reconstruction, particularly in arid and semi-arid zones, where suitable catchments for palynological archives are often limited. Preservation of organic material in northern Australia is characteristically poor, and wood charcoal analysis provides a viable alternative to understand shifts in woody vegetation in the past. The analysis of charcoal from matrix contexts at Riwi cave, located in the southern Kimberley region of northern Western Australia, has allowed a reconstruction of the local woody vegetation during occupation over the last 45,000 years. The wood charcoal assemblage from the Holocene stratigraphic units reflects the composition of the modern vegetation, and illustrates that people were occupying the site during periods of relative humidity. The Pleistocene stratigraphic units show a shift in vegetation composition from Eucalyptus spp. to Corymbia sp. dominated savanna, with an understory of secondary shrub, associated with a Late MIS 3 arid event observed in both terrestrial and marine archives, suggesting that activities continued at Riwi during this arid event. Further anthracological analysis of other sites in the Kimberley will help to build a regional picture of woody vegetation change, and will further disentangle local and regional climatic signals, particularly in relation to phases of occupation.

Wooden artefacts are seldom recovered from Australian archaeological contexts, limiting our understanding of an important component of past Indigenous socioeconomic systems. When recovered, the taxa used for construction are very rarely identified, and when undertaken, taxonomic identifications are generally unsubstantiated. For wood taxa to be identified, the microscopic elements of the xylem structure need to be observed and described from three planes. Conventional microscopy methods require physical sectioning, which is a complex, time-consuming process, whereas X-ray computed microtomography is non-invasive and expeditious. Here we describe the use of X-ray microtomography to identify the material of two wooden implements, the negative component of a fire drill and an artefact fragment, both recovered from Riwi cave in the southern Kimberley of Western Australia. By drawing on archaeobotanical analyses conducted at Riwi cave (wood charcoal and other macrobotanical remains), we are able to illustrate that the past inhabitants of Riwi selected certain woods for specific purposes within the last 1000 years of occupation at the site.

The rare recovery of hafting technology from archaeological deposits around the world prevents a clear picture of
Palaeolithic hafting arrangements. Without the recovery of hafted stone tools, our understanding of this technology
is limited to extrapolation from artefact morphology and ethnographic analogy, and such is the case in Australia.
Here we present a direct date of 3160–2954 cal. BP, obtained from resin on a stone point recovered from Carpenters
Gap 1 rockshelter in northern Western Australia. This artefact fits the description of point technology in Australia,
being a retouched flake with converging margins, and provides the first direct date of hafting resin in situ on a stone
tool from the Australian continent. The hafting arrangement of a stone point during the mid- to late Holocene is
archaeologically visible for the first time in Australia. This point was hafted using resin adhesive as well as wound
binding material. This rare artefact is used to discuss the current interpretations of technological change in the
Holocene record of Australia and the direct dating process.