Textural Characteristics of the Holocene Sandy Ridges in the Eastern Venetian Coastal Plain (North Adriatic Sea, Italy)

Abstract

In the lower Piave river coastal plain (northeast of the Venice Lagoon, Italy), evidences of ancient sandy ridges testify to both the local coastline progradation and retrogradation that occurred during the Holocene. Their arrangement is recognizable in aerial photographs as they appear as groups of parallel sandy strips. The orientation of each group of ridges differs from the orientation of the others. Even if the ridges have not preserved their original relief and morphology, weak undulations are still locally present. Through the joint interpretation of textural parameters and geomorphological observations and measurements, an attempt has been made to define the depositional processes responsible for the formation of these sandy ridges. The results from grain-size analyses have given evidence of the foreshore and the backshore environments. They have confirmed the presence of both aeolian deposits in most of the sampled sandy ridges and fine-grained filling sediments containing organic matter in the old inter-ridge depressions. The investigations have also confirmed the existence of a well-preserved abandoned Piave river delta and four subsequent main stages of coastal progradation interrupted by episodes of coastal retreat. Therefore, this research has provided new insights into the evolution of the Holocene Venetian coastal plain by adding new information on the different coastal depositional environments and transporting agents.