Department of Chemical and Geological Sciences, University of Cagliari, Italy

Mapping and luminescence aging of raised marine terraces and aeolian ridges along an ∼90 km coastal stretch in southwestern Sicily provide the first quantitative assessment of vertical tectonic deformation in this region, which spans the frontal part of an active thrust belt. We recognized a staircase of eleven terraces and nine related aeolian ridges. The elevation profile of terraces parallel to the coast shows a >90 km long bell-shaped pattern, onto which shorter-wavelength (∼10 km long) undulations are superimposed. Luminescence ages from terraced beach deposits and aeolian sediments constrain the position of paleoshorelines formed during MIS 5e, 7a and 7c, with a maximum uplift rate of ∼0.75 mm/a, and indicate a late Middle-Late Pleistocene (80–400 ka) age for the sequence of terraces. The elevation of Lower Pleistocene morpho-depositional markers points that uplift may have occurred at similar rates at the beginning of the Early Pleistocene, but almost zeroed between ∼1.5 and 0.4 Ma before the recent renewal. The uneven elevation of Middle-Upper Pleistocene paleoshorelines observed moving along the coast documents that uplift embeds both a regional and a local component. The regional, symmetric bell-shaped uplift is related to involvement in the thrust belt of thicker crustal portions of the northern African continental margin. The short-wavelength undulations represent the local component and correspond to actively growing bedrock folds. The present study contributes to unravel the different spatial and temporal scales of deformation processes at a collisional margin.

Recent works (Evelpidou et al., 2012) suggest that the modern tidal notch is disappearing worldwide due sea level rise over the last century. In order to assess this hypothesis, we measured modern tidal notches in several of sites along the Mediterranean coasts. We report observations on tidal notches cut along carbonate coasts from 73 sites from Italy, France, Croatia, Montenegro, Greece, Malta and Spain, plus additional observations carried outside the Mediterranean. At each site, we measured notch width and depth, and we described the characteristics of the biological rim at the base of the notch. We correlated these parameters with wave energy, tide gauge datasets and rock lithology. Our results suggest that, considering ‘the development of tidal notches the consequence of midlittoral bioerosion’ (as done in Evelpidou et al., 2012) is a simplification that can lead to misleading results, such as stating that notches are disappearing. Important roles in notch formation can be also played by wave action, rate of karst dissolution, salt weathering and wetting and drying cycles. Of course notch formation can be augmented and favoured also by bioerosion which can, in particular cases, be the main process of notch formation and development. Our dataset shows that notches are carved by an ensemble rather than by a single process, both today and in the past, and that it is difficult, if not impossible, to disentangle them and establish which one is prevailing. We therefore show that tidal notches are still forming, challenging the hypothesis that sea level rise has drowned them.