NEW EVIDENCE ON THE EVOLUTION OF THE PO-DELTA COASTAL-PLAIN DURING THE HOLOCENE

The Po coastal plain, dominated by the Po and Adige rivers deltaic sys tems, is characterized by beach ridges which mark successive positions of the coastline during the Holocene. The most evident of these ridge s are the most recent ones; their dating is mainly based on archaeolog ical and historical data. The complex formed by some of the most promi nent beach ridges was previously considered by experts to be the first post-glacial shoreline. This shoreline enclosed a single lagoonal sys tem comprising the lagoon of Venice and the delta of the main rivers. More recent studies have, instead, allowed us to recognize other beach ridges older than this one. These beach ridges are partially or total ly buried by alluvial sediments, belonging, we believe, to active Subb oreal shorelines. Additionally, other studies we are now carrying out, such as the Geomorphologic Map of the Po Plain and the Venetian Lagoo nal System Project, have allowed the identification of older buried in tertidal facies. This work proposes a progradational model mainly deve loped by the building of the marine deltas including episodic or disco ntinuous lagoonal environments, in opposition to the continuous lagoon al system model described up to now.