Shell Fragmentation Beyond Screen-Size and the Reconstruction of Intra-Site Settlement Patterns: A Case Study from the West Coast of South Africa
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.
- Ash, J., Faulkner, P., Brady, L. M., & Rowe, C. (2013). Morphometric reconstructions and size variability analysis of the surf clam, Atactodea (= Paphies) striata, from Muralag 8, southwestern Torres Strait, northern Australia. Australian Archaeology, 77, 82–93.Google Scholar
- Balbo, A. L., Madella, M., Vila, A., & Estévez, J. (2010). Micromorphological perspectives on the stratigraphical excavation of shell middens: A first approximation from the ethnohistorical site Tunel VII, Tierra del Fuego (Argentina). Journal of Archaeological Science, 37, 1252–1259.CrossRefGoogle Scholar
- Buchanan, W. (1985). Middens and mussels: An archaeological enquiry. The South African Journal of Science, 81, 15–16.Google Scholar
- Cannon, A. (2013). Revealing the hidden dimensions of Pacific Northwest Coast shell middens. In G. Bailey, K. Hardy, & A. Camara (Eds.), Shell energy: Mollusc shells as coastal resources (pp. 21–34). Oxford: Oxbow.Google Scholar
- Claassen, C. (1998). Shells. Cambridge manuals in archaeology. Cambridge: Cambridge University Press.Google Scholar
- Ford, P. J. (1992). Interpreting grain size distributions of archaeological shell. In J. Stein (Ed.), Deciphering a shell midden (pp. 283–325). San Diego: Academic.Google Scholar
- Hogg, A. G., Hua, Q., Blackwell, P. G., Niu, M., Buck, C. E., Guilderson, T. P., et al. (2013). SHCal13 Southern hemisphere calibration, 0–50,000 years cal BP. Radiocarbon, 55(4), 1–15.Google Scholar
- Jenkins, R. A. (2006). From midden to sieve: The impact of differential recovery and quantification techniques on interpretations of shellfish remains in Australian Coastal Archaeology. Unpublished Ph.D. dissertation, University of Queensland, Brisbane.Google Scholar
- Jerardino, A. (1995). The problem with density values in archaeological analysis: A case study from Tortoise Cave, Western Cape, South Africa. South African Archaeological Bulletin, 50(161), 21–27.Google Scholar
- Jerardino, A. (1997). Changes in shellfish species composition and mean shell size from a late-Holocene record of the West Coast of southern Africa. Journal of Archaeological Science, 24, 1031–1044.Google Scholar
- Jerardino, A. (1998). Excavations at Pancho’s Kitchen Midden, Western Cape coast, South Africa: Further observations into the megamidden period. The South African Archaeological Bulletin, 53, 17–25.Google Scholar
- Jerardino, A. (2007). Excavations at a hunter-gatherer site known as ‘Grootrif G’ shell midden, Lamberts Bay, Western Cape Province. The South African Archaeological Bulletin, 62(186), 162–170.Google Scholar
- Jerardino, A. (2012). Large shell middens and hunter-gatherer resource intensification along the West Coast of South Africa: The Elands Bay case study. Journal of Island and Coastal Archaeology, 7, 76–101.Google Scholar
- Jerardino, A., Fort, J., Isern, N., & Rondelli, B. (2014). Cultural diffusion was the main driving mechanism of the Neolithic transition in southern Africa. PLOS ONE, 9(12), e113672. doi: 10.1371/journal.pone.0113672.
- Maggs, T., & Speed, E. (1967). Bonteberg Shelter. The South African Archaeological Bulletin, 22(87), 80–93.Google Scholar
- Malan, A., Webley, L., Halkett, D., & Hart, T. (2013). People and places on the West Coast since AD 1600. In A. Jerardino, A. Malan, & D. Braun (Eds.), The Archaeology of the West Coast of South Africa (pp. 124–142). Oxford: Archaeopress.Google Scholar
- Mowat, F. M. (1994). Size really does matter: Factors affecting shell fragmentation. In M. Sullivan, S. Brockwell, & A. Webb (Eds.), Archaeology in the North: Proceedings of the 1993 Australian Archaeological Association conference (pp. 201–210). Darwin: The Australian National University.Google Scholar
- Muckle, R. J. (1985). Archaeological considerations of bivalve shell taphonomy. Unpublished M.A. thesis, Simon Fraser University, Burnaby.Google Scholar
- Muckle, R. J. (1994). Differential recovery of mollusk shell from archaeological sites. Journal of Field Archaeology, 21, 129–131.Google Scholar
- Noah, J. (2007). Application of a predictive method for estimating length from shell attributes: A case study from Argenvillei’s limpet(Scutellastra argenvillei). Unpublished B.Sc. Honours thesis, University of Cape Town, Cape Town.Google Scholar
- Peacock, E. (2000). Assessing bias in archaeological shell assemblages. Journal of Field Archaeology, 27(2), 183–196.Google Scholar
- Shiner, J. S., Fanning, P. C., Holdaway, S. J., Petchey, F., Beresford, C., Hoffman, E., et al. (2013). Shell mounds as the basis for understanding human-environment interaction in far north Queensland, Australia. Queensland Archaeological Research, 16, 65–91.Google Scholar
- Silberbauer, G. (1965). Report to the Government of Bechuanaland on the Bushman survey. Gaberones: Bechuanaland Government.Google Scholar
- Stein, J. K. (1992). Deciphering a shell midden. San Diego: Academic.Google Scholar
- Wessa, P. (2015). Free statistics software, Office for Research Development and Education, version 1.1.23-r7. Retrieved from http://www.wessa.net/.
- Yellen, J. E. (1977). Archaeological approaches to the present. New York: Academic.Google Scholar