A geomorphic framework for understanding the surface archaeological record in arid environments

We present data from Australian study areas that support episodic nonequilibrium as a suitable model for developing a theoretical and methodological framework for interpreting the surface archaeological record. According to this model, long periods of little or no geomorphic activity are punctuated by catastrophic events that erode or deposit sediments, and hence remove or cover up surface stone artefact deposits discarded by Indigenous people in the past. We demonstrate the impact of a single rainfall event on the surface archaeological record at one of our western New South Wales study locations. We then use the results of Optically Stimulated Luminescence (OSL) of sediments underlying the artefact deposits and radiocarbon dating of associated heat-retainer hearths to suggest that both landscape chronology and the surface archaeological record are reflections of a series of episodic events such as this rain event. We conclude that, at least in our study area, the archaeological record is discontinuous in time because geomorphic events have removed the record equating to particular time periods. This process is cumulative so that the record of recent times is much more common when compared to that from earlier times. The episodic nature of geomorphic processes also has an effect on human behaviour, such that occupation of place is discontinuous. The methods by which the archaeological record is surveyed and interpreted need to take into account these spatial and temporal landscape discontinuities.