Unlocking the past through the present : exploring the use of present-day land snail assemblages as indicators of past environments in the Maltese Islands

Abstract

Land snails from archaeological deposits are useful tools to determine past environments due to their often quite specific habitat requirements. Their value as palaeo-environmental indicators has been recognised by geologists since the 1940s, but it was not until the 1970s that the study of snails was brought into an explicit archaeological context.1 In the Maltese Islands, where the alkaline soils preserve their shells very well, the presence of land snails in archaeological deposits had been noted as far back as 1908.2 Land snails were listed in the Museum Annual Reports up to 1971, along with marine molluscs, and are likely to represent food remains due to the contexts in which they were found.3 Based on such food remains, possible deductions about the environment are rather limited. However, some Maltese archaeological deposits contain natural land snail assemblages. The first environmental studies using land snails were made in connection with the Xagħra Circle excavations in Gozo between 1987 and 1994.4 This study was groundbreaking as it provided the first scientific insight on the environment of a Neolithic site in the Maltese Islands. Other studies of natural assemblages in archaeological deposits followed.5 These studies showed changes over time in diversity and abundance for ecological groups conventionally defined by their habitat/microhabitat requirements as leaf litter (sheltered), open country (exposed), freshwater/wetlands (humid), subterranean and ubiquitous.6 One problem associated with the interpretation of land snail assemblages in the Maltese Islands is that it is based heavily on the ecological information in Giusti and colleagues,7 which, however is more pertinent to indicator species than to multi-species assemblages. This emphasises the need for new ecological studies on Maltese land snail assemblages in order to apply a holistic approach, using both individual species and species assemblages, in environmental interpretations that would hopefully lead to more precise results.