SlUlll ll ary.Sedimentological and palaeoecological observations, accompanied by archaeological determinations and absolute dating, have been carried out on a recent beach-barrier system succes sion located 20 km south of Siracusa, south-eastern Ionian coast of Sicily (Italy) . These deposits fi ll the back edge of a ria incised within Miocene limestones and are composed of three main stratal units characterized by distinct sedimentological fe atures. The two lower units, fo rmed by cross bedded sands and laminated days, recorded the development of a small confined beach-barrier depo sitional system, influenced by fr equent high-energy events. The upper unit, represented by chaotic coarser sediments, can be attributed to a destructive marine high-energy event. The physical prop erties of the composing stratal units and the morphological setting of the study area allowed us to reconstruct a suite of storm-and tsunami-related marine depositional processes that might have occurred in recent times along this area of elevated seismicity. In particular, absolute dating and archaeological determinations allow correlating the upper unit to a tsunami wave triggered by the 1693 AD catastrophic earthquake. The same depositional mechanism can also account for some of the coarse levels occurring into the underlying stratal units.

No abstract

A common problem facing sea-level researchers lies in determining the cause of rapid changes observed in coastal stratigraphic sequences. Such changes are commonly ascribed to the interaction of processes that operate over differing temporal and spatial scales, i.e. rapid local and regional sea-level trends and storm magnitude/frequency. At least some of the difficulty in distinguishing between these processes lies in the often limited stratigraphic database upon which palaeoenvironmental reconstruction is based. Here, we present the results of detailed morphostratigraphic and micropalaeontological investigations from a series of sites located at the interface between the protective gravel barrier complex of Dungeness and the barrier estuary sediments of Romney Marsh, England. A period of rapid coastal regression is identified between c. 4500 and 3000 cal. yrs BP, during which time the sea level continued to rise but was outpaced by sediment accretion and peat accumulation. A subsequent acceleration in the rate of rise led to a reversal of this excess of sediment supply over sea-level rise, and to rapid inundation of the entire barrier estuary between c. 2800 and 1900 cal. yrs BP. At the local level, coastal development reflects an interdependence between storms and long-term relative sea-level (RSL) rise; processes which lie at opposite ends of the magnitude/frequency spectrum. However, when viewed from a holistic perspective encompassing the Holocene development of Romney Marsh as a whole, storms are of secondary importance in controlling coastal evolution. Rather, our study suggests that at this macro-scale coastal evolution responds primarily to the combined effects of RSL rise and sediment supply.

AbstraetIn this paper, we present the results of bivariate plols of grain size parameters (mean againsl sorting) in the reconstruc¡ion of Holocene envíronmental change in coastal envíronmenls where barrier Fonnalion has had an important control on sedimentatíon. Sites on the North Atlantic coast with differing histories of climate, sediment flux, sea-Ievel change and barrier integrity are invesligaled lO delennine the general efficacy 01' this bivariate parameler model in dislinguishing between openand closed-basin conditions, and in reviewing lhe signillcance 01' aperiodic high-energy geomorphic events in controlling late slage back-barrier sedimenlalion.

No abstract