Absence of evidence or evidence of absence? Understanding the chronology of indigenous occupation of western New South Wales, Australia

Radiocarbon determinations obtained from heat retainer hearths in four sampling locations in western New South Wales, Australia are reported, with age estimates ranging from the mid Holocene until the last few centuries BP. Hearths are first considered in their geomorphic setting to determine the likely age of the surfaces into which they were dug and the reasons why they are still extant today. Second, the radiocarbon determinations are analysed not to date single events in the past, but to construct a regional chronology of Indigenous Australian occupation. In this chronology, periods when hearths were not constructed are as important as periods when radiocarbon determinations indicate sustained hearth formation. Third, comparisons are made among the four sampling locations to determine regional patterns. Results suggest both regional and local patterns of occupation and abandonment, or at least very much reduced hearth construction, over the last two millennia. The increasing frequency of radiocarbon determination results from hearths as one approaches the present is likely to be a result of the relative abundance of well preserved recent surfaces in the locations we have studied and the consequent lack of relatively ancient surfaces.