Traces of frost activity and ice segregation in Pleistocene loess deposits and till of Northern Italy: deep seasonal freezing or permafrost

In this paper the geomorphic history of aeolian sand of western Negev and northern Sinai is summarized on the bases of archaeological data and rediocarbon dating. Aeolian sands and sand dunes are associated with Epipalaeolithic sites (18,000-10,000 BP) and they lie on loess reworked by fluvial transportation that includes Upper Palaeolithic sites (30,000-20,000 BP). The deposition of the aeolian sand, therefore, slightly predates the last glacial maximum of the Late Pleistocene (Isotopic Stage 2). The source of the sand has been identified as the Nile Delta, which was exposed to a wider extent than present due to sea level drop. The dune incursion, from west to east, was gradual and time-transgressive but relatively rapid and was induced by hyperarid climatic conditions.