98 research outputs found

    Eurosion case study . Lu litarroni - La liccia - Isle of Sardegna Italy

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    The coast under study has been subdivided into 5 physiographical units. The physiographic area includes about 22 km of coastline, 10 of which of sandy beach, 5 of low rocky coast and 7 of cliffy coast. The outcropping rocks are those related to the Hercynian cycle, with the typical sequence of intrusive events represented by tonalites, granodiorites and leucogranitic plutons. The studied area includes includes only the sectors B and C. The wave-cut (cliff) stretches of coast, oriented according to these lineations are considerably fractured and crossed by tectonic lines perpendicular to the coast, on which processes of linear erosion and deep valleys have evolved. All physiographical units under study present maximum exposure to the winds and waves from west and north-west. The morphology of the submerged beaches of north western Gallura is strongly affected by the outcropping of the crystalline basement that determines its geomorphological arrangement The distribution of the dike set strongly affects coastal morphology by creating natural barriers to longitudinal transport, defining physiographic entities and creating tombolos and isolated rocks. La Liccia, Rena Majori and Bureddaggia are highly exposed beaches, liable to very intense swell with modest SW-NE net energy flow. Naracu Nieddu and Lu Litarroni beaches are poorly exposed, liable to intense swell with mild SW-NE net energy flow. Tourism represents one of the predominant sectors of the local economic systems and has influenced all other forms of the use of those parts of coast and sea, who have oriented themselves towards an organisation suitable for the needs of tourism. Tourist activities include various compartments of quality of the agricultural nutrition sector (to think about wine, cheese, bread and so on) and furthermore traditional and artistic trade or craft (fabrication of baskets, carpets, ceramics, knives, leather, wooden objects etc.). Of fundamental importance is the analysis of “progettualità” deriving from the socio-economic energies used for planning, programming (in particular of the local development programs, the instruments for urban development) and from those which regard actions in the area of the Quadro Comunitario di Sostegno also with the recent instrument of “Progettatione Integrata Territoriale” (PIT). With these reports it will be possible to verify a new scheme of territorial order, which directly originates from knowledge about the intentions of the local administration and the economic world in relation to the two principal objectives of development: -Strengthening and re-establishing entrepreneurship by productive investments in principally tourism-related activities, -Realisation, alignment and completion of infrastructural devices to be provided by the public (water pipes, the net of sewers, recycling…) and service

    The sedimentary bedforms in the channels of La Maddalena archipelago (NW Sardinia, Italy): a product of the holocene sea level rising

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    The use of a Chirp high-resolution acoustic source made it possible the differentiation of acoustic facies in the recentmost sediments of the channels of the La Maddalena Archipelago and the recognition of large scale bedforms linked to the last eustatic cycle. The acoustic facies, distinguished on the basis of their reflectivity characters, show a substantial coherence with the distribution of the sedimentary facies described by previous Authors. In the channels of the archipelago flat bottom sediments with medium to poor reflectivity correspond to sands, gravels and muds mainly of bioclastic composition deriving from the high CaCO3 productivity of the Posidonia Oceanica seagrass that populates the flanks of the channels down to about - 40 m. On the contrary sediments on the flanks, which are mostly non-reflective, are mainly represented by silico-clastic sands resulting from the degradation of the granitic structural highs. Sediments of the most proximal and protected bays are characterized by higher reflectivity and correspond to finer deposits such as silts and sandy silts. The Chirp survey highlighted the occurrence of large scale, low-H/L-ratio bedforms not evidenced on SSS survey because of their too low relief. In the channels roughly oriented W-E sedimentary bodies up to 3 km long and some meter thick occur in axial position. Two larger and thicker transversal bodies are present in two N-S trending channels, where they act as bathymetric thresholds between the adjacent islands. All these acoustically opaque bedforms, classified as sand ridges or sand banks are younger than the underlying sediments. They are mainly composed of bioclastic sands and gravels and represent the product of the present hydrodynamic regime. Seafloor undulations of sand wave type occur in the main channel along the Gallura coast down-flow to the headlands with respect to the dominant, eastward directed current. Symmetric forms may be attributed to stormy wave motion, while the asymmetric ones to the seabed current. Sand ridges and sand waves are significant sedimentary bodies in the archipelago depositional system as they witness the importance of the currents in the hydrodynamic regime. These features are overprinted by smaller sedimentary features such as comet marks, small scale sand waves, sand ribbons and ripple mark fields, which indicate the axes and directions of the sedimentary transport. The large-scale sedimentary bedforms of the channels of La Maddalena archipelago are the result of the hydrodynamic regime set up after the slackening of the sea-level rise, mainly between 6 -5 ky B.P. This event brought to the stabilization of the sea level and the formation and maintenance of the bedforms
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