The 5.5-4.5 kyr climatic transition as recorded by the sedimentation pattern of coastal deposits of Apulia region, southern Italy

Coastal marine Holocene deposits of the Apulia region, considered as indicators of palaeoclimatic conditions, were studied. Our data show that (1) up to c. 5500 cal. yr BP, a phase of accumulation of flint pebbles from the Gargano headland occurred at the Riviera sud di Manfredonia (Adriatic coast); their transport from the Gargano headland (north of the study site) is incompatible with the current northward littoral drift and is best explained by a prevalence and dominance of NE and E winds and (2) after c. 4500 cal. yr BP, there was a rapid accumulation of sediments at the Marina di Ugento (Ionian coast), which is best explained by a prevalence and dominance of S, SW and SE winds. The two different wind regimes identified can be explained by a change in the mean pressure configuration in the central Mediterranean. The first phase (until c. 5500 cal. yr BP) consisted of more frequent cyclogenesis to the east-southeast of the Italian Peninsula, followed by a second phase (from c. 4500 cal. yr BP) of more frequent cyclogenesis to the west-northwest. The period between 5500 and 4500 cal. yr BP represents a transitional phase between the two different regimes. In other words, there was a ‘retreat’ of the central Mediterranean cyclogenesis towards the west-northwest. This pattern is contemporaneous with the termination of the African Humid period. We interpret both the ‘retreat’ of the Mediterranean cyclogenesis and the termination of the African Humid period as the expression of an expansion of the tropical dry Saharan belt.