Carbonate microfacies in shell middens of northern Iberia: implications for Holocene environment and Mesolithic settlement

Summary

In the Cantabrian region (northern Spain) the exploitation of marine resources is well known. This is especially true during the Mesolithic, as attested by the particular record of carbonate-cemented shell middens in caves and rockshelters, although only a few sites have shell middens in stratigraphic position, allowing archaeological excavation.

Recent investigations at three sites, El Alloru, El Mazo and La Fragua, demonstrated that these deposits record a complex accumulation of calcium carbonate forms, with juxtaposed microfacies resulting from both human inputs of Ca (e.g. combustion features and the shells themselves) and the posterior carbonate cementation by karstic hydrological activity. In addition, postdepositional processes led to the precipitation of secondary carbonate crystals throughout the deposits. Differentiation between each form of calcium carbonate is possible through petrographic (thin sectioning), mineralogical (FTIR), and geochemical (SEM) analysis. This approach permits the identification of carbonate forms such as tufa, stromatolitic structures, calcitic ash, and secondary recrystalizations, achieving great detail in their spatial and chronological interactions.

It is concluded that microcontextual multitechnique approaches to the carbonate microfacies of the shell midden are highly informative regarding a higher-resolution record of local Holocene conditions, the integrity of the human activities, and therefore, the functionality of these deposits.

This Resource is Part of the Following Collections

• Society for American Archaeology 81st Annual Meeting, Orlando, FL (2016)   •
• Shell Midden Microarchaeology Unraveled

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