Coastal dunes are mounds of sand which are formed along the coasts mainly by the winds, often in combination with the action of storm waves and landward alluvial events.
The sand from the beach or from nearby streams can be taken up by the wind and accumulated to the back of the beach, thus forming deposits of varying shapes and sizes, known as dune fields. The shape of the dunes depends on the particular geological, geo-morphological, sedimentary, exposure and climate conditions of each site.
Both marine and land vegetation also plays an important role in originating and maintaining dunes. In particular, land plants help to build and stabilise dunes.
The remains of sea vegetation washed up on the beach, especially Posidonia oceanica, together with other organic material, often form the first nucleus of dune formation.
As to size, dunes may vary from small sandy hillocks, covering a few square metres less than one metre in height, to imposing sedimentary masses extending for several square kilometres and reaching heights of more than ten metres.
The information listed here has been taken from:
Sandro De Muro, Gianni De Falco, Maurizio Costa
For more information visit the website www.osservatoriocostesardegna.eu