Here and there: Links between stone sources and Aboriginal archaeological sites in Sydney, Australia

The main aims of this research were to identify the distribution of potential sources of flaked stone found in Aboriginal archaeological sites in Australia's Sydney region, and to find methods suitable for directly relating artefacts and source materials. Ethnohistoric evidence for the procurement, manufacture or use of flaked stone in the region in the late 18th century (at "contact"), is sparse but tends to suggest that little was being used, particularly in the coastal zone. However, since the late nineteenth century, considerable quantities have been found throughout the area, in archaeological sites spanning many millennia. Previous attempts to identify stone sources relied on data from geological research, archaeological reports, word of mouth or chance discovery. Inadequacies in the data often resulted in source misidentification, with many types of stone thought only to be available beyond the region - a factor which would have necessitated the involvement of long-distance trade/exchange systems and all the social interactions these entail. This research demonstrates that all stone raw materials in Sydney archaeological assemblages are available in the Sydney region, mainly from Tertiary and Quaternary gravel beds, and that these are widely scattered. Studies aiming to characterise and identify rock from potential sources, mainly silcrete, had mixed results. Examination of whole rocks, fragments and thin sections was undertaken or commissioned. Experts' descriptions of the same rock type, from the same sources, tended to differ in quite significant ways. Other analyses indicated that discrimination between some regions might be possible but that variation within rocks from individual locations is often greater than between locations. PIXE-PIGME analysis supported this finding. Heating experiments showed that red colouration of silcrete and IMTC (indurated mudstone/tuff/chert) is an unreliable source indicator - yellow rock turns red when heated, which can happen to source material or artefacts, accidentally or deliberately, at any time. Conversely, yellow artefacts have not been heated and their colour may help to identify a source. In most analysed assemblages, the highest percentage of flaked stone, numerically, is silcrete or quartz, depending on site category and location - quartz predominates in rockshelters in the deeply incised sandstone areas, silcrete is dominant in open "campsites" on the less rugged Cumberland Plain. Variations in raw material abundance mainly seem to correlate with distance from potential sources. However, evidence suggests that, where a number of other knappable rock types were also available, silcrete may have been preferentially selected. Analyses also demonstrated that quartz discard rates in rockshelter sites (all of which are near to potential sources of quartz) changed through time - more was discarded in recent years, compared to other raw materials which were dominant earlier. This may signal changes in mobility or territoriality. This research should dispel some myths about raw material availability and use in the Sydney region and add new information about the materials themselves, where to find them and which techniques may and may not be worthwhile in relation to future research.