Landslides and climate change in the Italian Dolomites since the Lateglacial.

The paper deals with the relationship between the temporal occurrence of landslides and climatic changes in the Italian Dolomites since the Late glacial. After an introduction on the state of the art, with particular reference to the Alpine region, the results of recent investigations in the two study sites are illustrated. At Cortina d'Ampezzo, several landslides were dated mainly by the radiocarbon method. The most ancient landslide event there involved large rock slides, which affected the dolomitic slopes following the withdrawal of glaciers after the Last Glacial Maximum (LGM), and also slides and flows mainly occurring in pelitic materials of the valley floors (from 13,000 to 10,000 cal BP). A later series of flows occurred between 5500 and 2500 cal BP. In the Upper Badia Valley (Alta Badia), the most ancient events go back to 10,000 and 9000 cal BP, and correspond with earth flows that followed vast rotational slides affecting the bedrock up to a depth of about 50 m. More recent earth flows, involving more modest amounts of material, took place between 6500 and 2300 cal BP. By analysing the dates from the two study areas, it was possible to correlate the recorded increase of landslide activity with the climatic changes occurring at the boundary between the Late glacial and the Holocene and between the Atlantic and the Subboreal, and to compare the results with those derived from other European regions. The types and causes of landslides taking place in these two periods were substantially different, reflecting the different morphoclimatic conditions that existed in the two areas when these mass movements were triggered. Finally, notwithstanding the importance of non-climatic causes, such as geological-structural factors and possible human influences, it is concluded that many of the dated landslides can be considered as indicators of climatic change.