When grouped together, radiocarbon determinations from heat-retainer hearths from western New South Wales decrease in frequency with age. One interpretation for this pattern is that it reflects an increase in the frequency of occupation, and perhaps ultimately an increase in Aboriginal populations in this region during the late Holocene. An alternative explanation is that the increase in frequency reflects the differential preservation of the land surfaces on which the hearths are found. According to this explanation, the pre-servation of ancient surfaces itself decreases with time, with the destruction of ancient records of occupation accounting for the relatively recent skew in the age distribution of heat-retainer hearths. We test these hypotheses by comparing the distribution of hearth radiocarbon ages against the distribution of ages obtained from samples associated with buried human remains from western New South Wales. Samples obtained by excavating buried deposits should not be subject to the same range of erosion processes that have affected surface deposits. Therefore the samples from buried deposits are able to act as a control against which the distribution of hearth ages can be evaluated. Results indicate that age estimates obtained from human burials have a distribution different from those obtained from hearths, supporting the conclusion that the decrease in hearth frequency with age is a product of geomorphic preservation rather than cultural change.