Some observations on the occurrence of the shell Hygromia hispida (Linné) during the Last Glaciation and in Holocene times

Abstract

Evidence suggests that wherever there occurs a sudden and large increase in numbers of the shell Hygromia hispida (constituting more than 40% of the total) a large increase likewise takes place in the total number of shells of other species present in such a deposit. This numerical optimum was reached during a late interstadial of the Last Glaciation, during the closing stages of the Late Glacial period, as well as in the Sub-Atlantic phase of Holocene times. A study of deposits, covering this span of time, suggests that there was but one period during which H. hispida and thermophile species of shells have similar quantitative distribution in relation to the rest of the land molluscan fauna present. This occurs in the latter portion of the Bronze Age and the first part of the Early Iron Age. The presence of marsh- and/or freshwater-shells in a deposit does not appear to influence the quantitive distribution of H. hispida