Age, soil-forming processes, and archaeology of the loess deposits at the Apennine margin of the Po plain (northern Italy): New insights from the Ghiardo area

The significance of two loess profiles located in the Ghiardo area (Reggio Emilia, northern Italy) along the southern margin of the Po Plain is discussed on the basis of sedimentary and pedological data, optically stimulated luminescence (OSL) dating, and archaeological context. Loess sedimentation occurred during cold and arid glacial and stadial periods of the Upper Pleistocene, between c. 70 and 35 ka. In the same time interval, loess sedimentation occurred at other localities at the northern margin of the Po Plain (Po Plain Loess Basin). The early period of loess sedimentation was contemporary with an intense frequentation of the area by Palaeolithic hunters, whose remains, consisting of clusters of flint artefacts, are found at the base of the loess sequences. Thermoluminescence dates on burned flints are consistent with OSL measurements on sediments where lithics were found and therefore the archaeological finds may be attributed to the Middle Palaeolithic lithic complexes of the Mousterian culture. Subsequent soil-forming processes on the loess deposits during the Holocene are suggested by changes in the proprieties of the profiles (clay illuviation, hydromorphic and vertic features, mukkara/gilgai microrelief). Degradation processes of the topsoil, leading to the formation of an eluvial top horizon, were eventually triggered by deforestation, which took place in the area since the Chalcolithic period (middle Holocene).