Stone artifact scatters in western NSW, Australia: Geomorphic controls on artifact size and distribution

Abstract

Surface scatters of Aboriginal stone artifacts have been exposed in many parts of inland Australia by accelerated erosion that followed the introduction of pastoralism by European settlers in the 19th century. This paper reports on a set of techniques developed to investigate and quantify the effects of these post-discard disturbance processes in Sturt National Park in northwest NSW, Australia. Backwards, stepwise, linear regression showed the influence of geomorphic parameters such as slope gradient, elevation, landform, and contemporary surface processes on artifact distribution, with artifact maximum dimension as the dependent variable. The results indicate that, even at low gradients, artifact size and slope angle are significantly related, but that the variance in maximum dimension explained by gradient is very low. Similar results were found for the other geomorphic variables. We conclude that artifact movement by surface wash across these surfaces is unlikely to significantly affect artifact distribution. While vertically conflated surface scatters do not preserve "living floors" in a short-term, functional sense, their apparent horizontal integrity allows investigation of the long-term use of place by hunter-gatherer people in the past. Insofar as assemblage integrity is important for assessing site significance in the heritage management industry, our methods provide a means for assessing the degree to which a site has been damaged by water flow. ᭧

The surface archaeological record in arid Australia: Geomorphic controls on preservation, exposure, and visibility

“…On individual scalds, artifacts are clustered in high-density patches with intervening areas of lower density, rather than being spread uniformly across the surface (Figure 3). This spatial pattern, together with analyses of the relationships between artifact size and various topographic parameters (Fanning & Holdaway, 2001a), illustrates the conclusion reached here, while the vertical integrity of the original artifact deposits may be lost, the lateral integrity remains intact. The high visibility of the record is one of the factors that attracted us to work in western NSW, but interpreting the significance of the quantity of artifacts visible, as well as those that remain buried, must be related to the geomorphic history of the sediments on which they rest.…”

“…On slopes greater than two degrees, overland flow can also move small artifacts [with a maximum clast dimension (b axis length) less than 20 mm]. Lateral movement is much less discernible among the larger artifacts, as demonstrated by our own studies (Bryant, 2007;Fanning & Holdaway, 2001a), experimental work carried out by Schick (1987), and the results of hydrological modeling in one of our study areas (Pigdon, 1997). In areas where water flow is concentrated, such as rills, gullies, and channels, there is the potential to move all artifacts; however, these geomorphic features cover only a small area of many scalds.…”

“…Using maximum clast dimension (b axis length) as the dependent variable, regression analyses testing the impact of contour interval and gradient were run. Results of the regression (Table II) indicate that both the steepest slopes and lowest contour intervals (i.e., closest to the channels) have significantly larger artifacts than flatter slopes or higher surfaces, evidence consistent with winnowing of smaller artifacts by sheet wash (Fanning & Holdaway, 2001a).…”

“…Overland flow moves artifacts resting on surfaces with gradients greater than two degrees (Bryant, 2007;Fanning & Holdaway, 2001a the poorly sorted, mixed load deposits that are characteristic of ephemeral dryland streams. Because sediment loads are high, the volume of stone artifacts eroded and transported is likely to be low relative to the total volume of sediment eroded at any one location, adding to the loss of artifact visibility.…”

Experimental lithic tool displacement due to long-term animal disturbance

“…However, the downslope movement Rick (1976) observed was on surface exposures on fairly steep slopes (> 10°). Fanning and Holdaway (2001) found that downslope artifact migration with shallower slopes is less pronounced and found a slight, but significant, positive correlation between artifact length (on artifacts > 20 mm) and slope in Australian contexts for a very large dataset (n = 17,128). However, only slopes between 0°and 5.6°were analyzed, which make the results with Rick (1976) difficult to reconcile.…”