many sites investigated through archaeology appears to have ensued. Evidence for the Aboriginal use and occupation of the Sydney region from this period is therefore far more "archaeologically visible" than for previous periods. In the South Sydney region at least three archaeological sites have produced dates of Aboriginal occupation that range from between 3,000 and 5,000 years ago. From about 3,000 years ago to Contact the number of occupied sites appears to have increased dramatically. This may reflect a "real" increase in the number of sites (and hence people) in the region, or may reflect preservation factors (particularly associated with shell midden deposits) where older sites have been destroyed by thousands of years of erosion, and accelerated by development in the post-Contact period. Over the 20,000 years of Aboriginal occupation in the region, and in particular the last 5,000 to 8,000 years, numerous changes in excavated stone tool assemblages have been observed. Various temporal markers have been established by archaeologist in an attempt to distinguish what are considered to be the more significant changes in tool types and tool kit composition. The assumption being that changes in one (or more) components of the excavated material culture may reflect changes in other aspects of past Aboriginal social, economic and technological practices. These arguments are based upon changes in stone tool assemblages and observable changes in the use of certain types of stone used in Aboriginal tool manufacture. Excavation of a number of rock-shelter occupation sites in particular indicates that the earlier phases of occupation are largely characterised by the presence of large cores and scraper tools. This appears to be followed by the addition of a variety of smaller backed implements (known variously as backed blades, geometric microliths or Bondi Points) to the toolkit previously dominated by larger tools at around 5,000 years ago. By around 1,500 years ago the smaller backed forms appear (on available evidence) to have gone out of use and excavated site assemblages are characterised by quartz bi-polar artefacts and more opportunistic or undifferentiated small tools. It is reasonable to assume that the many artefacts made by Aboriginal people from shell, bone or wood as observed at Contact were also used in the past but these materials have not survived in the archaeological record. Research indicates that coastal sites in the Sydney region have been largely ignored by archaeologists until relatively recently. Prior to work completed over