Short term camps or long term accumulations? Dating heat retainer hearth clusters in western New South Wales, Australia

Surface archaeological deposits are widespread in arid Australia, but have received relatively little attention by researchers owing in part to the difficulty of providing chronological constraint. Heat-retainer hearths, or earth ovens, are most often found in association with stone artefact deposits, and radiocarbon determinations on charcoal from the hearths are beginning to provide a powerful means for developing a chronology of Holocene occupation of the locations in which they are found. We report on recent archaeological survey results where 865 hearths were identified along a 10 km section of Rutherfords Creek in the Paroo Darling National Park in western New South Wales, Australia. In some areas erosion has exposed clusters of hearths, some of which preserve charcoal suitable for radiocarbon age determinations. However, partial excavation of the hearths is required to obtain charcoal and is of concern to Aboriginal custodians and heritage managers charged with protecting the remains of cultural activity. Optically Stimulated Luminescence (OSL) dating provides an alternative method which may be applied in these contexts. We present preliminary OSL dating results for heat-retainer hearth stones, providing age estimates of the last heating event. These results are compared to radiocarbon determinations on charcoal from the same hearths, and provide powerful evidence of the potential of OSL for directly dating the hearths. Analysis of the results from four spatially separated clusters of hearths allow us to determine whether space and time are correlated, that is, whether hearths that are close to one another have similar ages. These results provide an insight into the types of behavioural inferences that can be derived from the surface archaeological record in Australia.