Water-worn shell and pebbles in shell middens as proxies of palaeoenvironmental reconstruction, shellfish procurement and their transport: A case study from the West Coast of South Africa

Geoarchaeological studies today are a vital component of archaeological research. The sedimentary environments of coastal settings in particular are highly dynamic and governed by a variety of factors among which changes in sea level play an important role. The object of such studies often involves the study of sediments deposited by natural factors in overlapping geological and anthropogenic contexts. Archaeomalacological studies conducted on shell middens along the West Coast of South Africa in the last two decades have also identified the presence of additional natural components that became incorporated into archaeological sites through active but inadvertent human agency. These sediments are relatively large particles (2-20 mm) of water-worn shells and water-worn pebbles (WWSP) that became entangled among the byssus threads that rocky shore mussels use for attaching themselves to hard substrate. Prehistoric shellfish foraging and subsequent transport of rocky shore mussels along with their byssus contents to campsites ensured the inclusion of WWSP into archaeological middens. This study shows that WWSP abundances and the proportion of their organic fraction (water worn shell) can be used as proxies for coastal palaeoenvironmental reconstruction and as a complement to archaeomalacological studies for inferring technologies involved in shellfish collection and transport. Conclusions presented here probably apply to other similarly configured shorelines and shell assemblages of comparable age from elsewhere in southern Africa and beyond. Follow-up studies from this sub-region and beyond might confirm and/or qualify the use of WWSP observations in other coastal settings.