A multidisciplinary analysis of shell deposits from Saltés Island (SW Spain): The origin of a new Roman shell midden

The analysis of shell deposits eroded by a ebb-tide channel on Saltés Island (Tinto-Odiel estuary, SW Spain) resulted in the identification of a new shell midden, associated with the activity of a nearby Roman factory over the 4th-5th centuries CE. This midden differs from other old shell deposits (sandy tidal flats, cheniers, washover fans) in several features: a) its malacological content, dominated by edible species (mainly the bivalve Glycymeris nummaria) and differentiated by statistical analysis; b) a partial selection and better conservation of Glycymeris nummaria (Linnaeus), its most abundant species; c) the absence of microfauna, which implies a previous washing to its final deposit; and d) an age concordant with the one deduced from the Roman amphoraic remains found in this area and subsequent to the washover fans on whom it was deposited. All these features, together with the absence of both anthropic fractures or cooking, would indicate that this Roman shell midden was the end result of a trawling on subtidal Glycymeris-rich sandy bottoms with adjacent grasslands, where the gastropod Bittium reticulatum (da Costa) was the most abundant mollusc. This gastropod is the dominant species in the remaining shell deposits. [Display omitted] •Multidisciplinary analyzes permit to distinguish shell middens from other shell deposits.•Percentages of edible species, taphonomy or shell size delimit shell middens.•Statistics permits to delimitate shell middens from cheniers, washover fans or tidal flats.•Autoecology of the species delimits the fishing spaces of a Roman factory and the fishing techniques used.•Age of shell midden is consistent with that of the nearby archaeological remains.