Sea-level change along the French Mediterranean coast for the past 30 000 years

Observational evidence for sea-level change along the French Mediterranean coast has been examined and compared with glacio-hydro-isostatic models to predict the spatial and temporal patterns of change for about the past 30 000 C-14 years. These predictions are pertinent to discussions of changing ocean volumes during this interval, the tectonic stability or otherwise of the coastal areas, mantle rheology, and the timing of possible human occupation of the now submerged coastal plain and caves, such as Cosquer Cave near Marseille. The principal results from the analysis are: (i) sea levels along this section of the coast have risen continually since the time of the last glacial maximum (LGM) and at no time during the Holocene has the mean sea level been higher than that of today. (ii) The coast has been tectonically stable between Marseille and Nice as well as further to the west in Roussillon. Western Corsica may have experienced a slow tectonic uplift of between 0.15-0.3 mm/year for the past 3000 years but northernmost Corsica appears to have been stable during this same interval. (iii) During the LGM, sea levels along the coast and immediate off-shore areas stood at between 105-115 m below present level, the range reflecting the importance of the isostatic contributions. During oxygen isotope stage 3, sea levels do not appear to have risen locally above about -60 m. (iv) The rebound parameters (describing the mantle rheology and ice sheets) required to match the limited observational evidence are consistent with the results of similar analyses carried out for other parts of Europe. Because of its distance from the former northern ice sheets, the isostatic factors are particularly sensitive to the value of the lower-mantle viscosity. (v) The model predictions for sea-level change at the Cosquer Cave site and for its immediate environments indicate that the cave was last readily accessible before about 10 700 +/- 500 C-14 years (about 12 500 +/- 500 cal, years) BP and that the cave entrance was completely flooded by 9000 +/- 200 radiocarbon years BP (between about 9800 and 10 300 calibrated years BP), The cave was above sea level throughout the oxygen isotope stage 3. (C) 2000 Elsevier Science B.V. All rights reserved.