Shell Fragmentation Beyond Screen-Size and the Reconstruction of Intra-Site Settlement Patterns: A Case Study from the West Coast of South Africa
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Zooarchaeologists normally screen shell remains through stacked meshes of different sizes to assess the degree of fragmentation of this material. This kind of quantification serves the purpose of characterizing stratigraphic sequences and reconstructing intra-site settlement patterns and site formation processes. However, screening can be time consuming, add an additional step to the processing of faunal remains, and pose complexities when storing shell samples. Moreover, it is not always clear whether the interpretations of changes in shell fragmentation in terms of behavioral patterns are well justified without contrasting them against independent evidence.
This chapter presents an alternative proxy-measure of shell fragmentation without screening and by relying on the quantification of diagnostic shell parts that are in two different states of preservation. The case study in question is based on the South African black mussel (Choromytilus meridionalis), one of the most common species of molluscs observed in South African West Coast shell middens. The results show that, in the absence of major taphonomic alterations that can substantially modify the chemistry of a shell matrix (e.g., burning and dissolution) and therefore increase their vulnerability to breakage, low levels of shell fragmentation correlate with higher deposition rates resulting from longer visits. This behavioral inference is supported by independent quantitative data on material culture. On the other hand, shell fragmentation does not seem to depend on shell density or the original shell size, at least within the range of shell sizes considered in this case study. Changes in the percentage of black mussels among other taxa may be a minor but contributing factor in black mussel preservation, but this is yet to be determined with further studies. Insights into intra-site settlement patterns and characterization of regional settlement patterns may be gained through the comparison of shell fragmentation data from several sites. This analytical approach can be applied to other mollusc species and in different geographic and cultural contexts within South Africa and elsewhere in the world.
KeywordsShell taphonomy Shell preservation Choromytilus meridionalis Shell middens Elands Bay
Excavations at Pancho’s Kitchen Midden and subsequent analyses were co-funded by the SWAN FUND (Oxford University), a Center for Science Development (South Africa) grant to the Spatial Archaeology Research Unit at the University of Cape Town, and a University of Cape Town field work grant to the Department of Archaeology at the University of Cape Town. I am very grateful to Mr. T. Smit for allowing our team to undertake fieldwork in his farm of Verlorenvlei and to R. Yates for his support in the field, interest, and discussion of results over the years. Many thanks to P. Faulkner for sourcing bibliography not available locally and to two anonymous referees for their useful comments and suggestions on earlier versions of this paper. Any errors are my own. Francesc Conesa kindly compiled Fig. 8.1 and greatly assisted with Fig. 8.4. I am very grateful to George Branch for generously sharing a photograph of a Choromytilus meridionalis shell. I wish to extend my sincere thanks to P. Bardone, J. Du Toit, N. Erlank, U. Evans, G. Hall, S. Hall, A. Leatt, M. Loopuyt, A. Manhire, L. Manning, B. Mütti, R. Nackerdien, A. Neale, P. Nilssen, J. Plantinga, J. Reynard, K. Sadr and E. Wahl for their help in various excavation seasons.
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