La piana costiera del fiume Liscia (Sardegna nord-occidentale)

The coastalplain of the River Liscia (Northern Sardinia, Italy)

Abstract

The coastal plain of the river Liscia represents one of the deepest and most extended coasts of the northern sector of Sardinia. The portion of emerged ground has shown a predominance of structural forms, associated with the crystalline basement and its petrographical variations. Along the coastal perimeter aeolian processes induced by the west winds have produced the most significative shapes. The evolution of the river Liscia was traced back on the basis of historic maps, which was followed by a series fo aerial photographs. Significant variations both of the course of the river and of the perimeter of the coast were observed. These variations were also supported by the results from grain size analyses and in situ measurements. The transport of fine grained material from east to west and the presence of some terraces with material of different grain sizes and at different depths has created the distinctive morphology of the seabed of the rias of this area. The rias bottom is occupied by clay silt, whose origin may be associated with the withdrawal of the coast along the old palustrine deposits. A paleopool of the river Liscia was located at a depth of about ten metres, in the vicinity of an old abandoned meander. We have tried to reconstruct the recent evolution of the plain, which was periodically subjected to marine ingression and to the fluvial dynamics of the river Liscia in the Upper Pleistocene. Forms and deposits testifying deep transformations along the Inner have been located, whereas In the Innermost part of the coastal plain the landscape was not particularly affected.