Multidisciplinary study of late Pleistocene and Holocene paleoenvironmental changes and human impact in the archaelogical site of Palmi (SW Calabria)

A multidisciplinary study was carried out on a pedostratigraphic succession excavated in “Piani della Corona” archaeological site, located on a marine terrace in the surroundings of Palmi city (SW Calabria). We integrated archaeostratigraphic, pedological, anthracological, tephrostratigraphic, isotopic and geochronological approaches. The upper stratigraphy consists of soils horizons spanning from middle to late Holocene, which include late Neolithic to late early Bronze age settlements and lithic and ceramic artefacts, overlaid by arable layers of undetermined age. The lower portion of the stratigraphic succession shows no archaeological finds, but its bottom was ascribed to late Pleistocene on the basis of a radiocarbon date (27650±250 a BP). This chronology is coherent with the chemical composition of volcanic glass identified using SEM-EDS, which suggests a provenance from late Pleistocene-Holocene eruptions of the Aeolian Arc. Environmental changes were reconstructed along the pedostratigraphic succession. Pedological data evidenced late Pleistocene cold-humid conditions indicated by more abundant short-range order minerals (SROM) probably during an interstadial predating the LGM, as SROM formation is favoured by the weathering of volcanic material under prolonged moisture conditions. The late Pleistocene to early Holocene climate amelioration until the Neolithic climatic optimum, characterized by an increase of humidity and temperatures, is evidenced by the presence of clay coatings, coupled with dominance of phyllosilicates over SROM, as their formation is favoured by warm-humid conditions and seasonal contrast, higher during the climatic optimum. The upper part of the succession records a return to humid conditions, indicated by more abundant SROM and disappearance of clay coatings above the Bronze age paleosurface. The latter and the Neolithic soils are widely affected by soil truncation and anthropic influence (pole holes, cisterns, ditches, plough furrows). Typical soil features related to tillage were also observed at the microscale. Soil charcoal analysis evidenced the dominance of herbaceous taxa during the late Pleistocene, followed by oak forest that persisted during the climatic optimum and after the late Bronze age, suggesting a relatively limited spatial extension of human impact.