Grain size characterization of modern and ancient dunes within a dune field along the Pisan coast (Tuscany, Italy)

In this paper, grain size analysis on a large number of samples from a dune field within the Migliarino – San Rossore – Massaciuccoli Regional Park has been carried out in order to define the textural characterization of modern and ancient dune ridges. More than 200 samples along five transects have been collected from the backshore, the active dunes and the steady dunes up to the last recognizable dune ridge. The samples have been dry-sieved and the obtained data have been processed electronically to achieve textural parameters such as mean diameter and sorting. The results showed similar trends of the transects throughout the entire dune field. In particular, the grain size tends to decrease towards the most ancient dune ridges, showing a significant drop at the transition between active and inactive areas. The drastic decrease might be related to a possible variation of River Arno sediment discharge occurred after the XVIII century.