Paleochannels and Patches: A Geoarchaeological Assessment of Silcrete Sources in the Cumberland Plain, Eastern Australia

Although Aboriginal occupation dates to the Pleistocene, silcrete artifacts only begin to dominate archaeological sites found in the Cumberland Plain of western Sydney, eastern Australia, during the mid‐late Holocene. These assemblages routinely include large numbers of backed artifacts. A geoarchaeological survey of five potential silcrete source areas found that silcrete is irregularly distributed along ridgelines within gravel patches that represent paleochannel remnants. Thus, particular parts of the landscape, dictated by the geological history, were more likely to be targeted for stone procurement. The quality of silcrete differs between and within the sources due to variations in grain‐size, degree of silicification, and presence of inclusions/fractures, as well as the destructive influence of bush fires on exposed cobbles, resulting in an overall low abundance of high‐quality silcrete across the Cumberland Plain. Furthermore, a rind or chalky weathering cortex on many cobbles means that testing was required to assess the internal raw material quality. The difficulty in locating suitable raw material for artifact manufacture meant that when good silcrete sources were found, they were heavily targeted. This contextual information provides an essential backdrop in which to understand the archaeology of the Cumberland Plain and broader patterns of landscape use.