The Central Mediterranean

B ecause of their geologically young age and com- plex geological setting, central Mediterranean shelves show a large variability in morphol- ogy (width, slope, unevenness), stratigraphy (different thickness of depositional bodies resulting from the last climatic/eustatic cycle) and sedimentology (shelf-mud offshore of the main river mouths, bioclastic sediment in under-supplied areas). The overall morphology usually encompasses a well-defined shelf break as deep as 120m to 150 m; above this depth, a well-developed erosional unconformity cutting across older deposits is present, overlaid by the depositional sequence formed in the last 20,000 years during the last sea-level rise and the present highstand of sea level. The thickness of such a sequence is highly variable, from many tens of meters offshore of the main rivers (e.g. the Po and Tiber) or in tectonically active areas (e.g. the Ionian Sea), to a few decimeters on insular shelves or on uplifting regions with arid climates (e.g. Apulia and the volcanic islands of the Tyrrhenian Sea). Accordingly, the shelf is floored by detrital siliciclastic sediment in well-fed areas that show sandy shorelines and muddy shelves with a mud line located at about 20 m, and by bioclastic sand and silt in underfed areas. The morphology of the shelf is profoundly con- ditioned by the tectonic and sedimentary setting. In stable/uplifting and underfed areas, bedrock may outcrop and create a complex setting of shoals and paleo-headlands. In subsiding and well-fed areas the shelf is usually flat, with a slope of a few tenths of a degree.