Human-landscape interactions in the Bologna area (northern Italy) during the mid-late Holocene, with focus on the Roman period

Integrated sedimentological and archaeological investigations of mid-late Holocene deposits from the subsurface of Bologna elucidate the complex relationship among urban settlement, human society, geomorphology and climate change at the southern margin of the Po Plain. Above the Pleistocene-Holocene unconformity, the Holocene succession forms an intricate mosaic of alluvial deposits. Two palaeosols, spanning between about 8000-5000 cal. yr BP and 3200-1500 cal. yr BP, respectively, represent the most prominent stratigraphic markers across the study units. A huge amount of archaeological remains from the younger palaeosol enables the identification of an uninterrupted sequence of settlements from the Early Iron Age to the Late Roman period. The first permanent settlements of Iron Age took place in a topographically elevated region protected from flooding. The onset of paedogenesis during this period reflects the radical transformation of the environment by human settlements through widespread control of the river network and setting of regular patterns of irrigation channels. A period of exceptional climate stability characterized the expansion of the Roman Empire. This phase is testified by a wealth of exceptionally preserved archaeological material, including buildings, cemetery sites, streets and irrigation channels. Subsurface correlations of the Roman palaeosol enable detailed reconstruction of the Roman topography, with special focus on fluvial paths and communication routes. The decline of the Roman Empire, hit by a devastating epidemic and the barbarian invasions, was paralleled by a phase of climatic deterioration, resulting in the abandonment of rural lands and degradation of the river network, which ultimately favoured the burial of Roman settlement.