The Italian Mountains: glacial landforms from the Bølling–Allerød Interstadial (14.6–12.9 ka)

The effects of the Bølling–Allerød warm period on the environments of Peninsular Italy were registered by several terrestrial and marine climate proxies. The landscape was characterised by thermophilic and xerophilic vegetation at low altitudes, coniferous and deciduous woods up to altitudes above 1000m where lakes were almost totally absent or experienced a negative hydrological balance with strong processes of evapotranspiration. In the Apennine glacial chronology, the correlation of the various palaeoenvironmental data make it possible to define the Venaquaro Interstadial as equivalent to the Bølling–Allerød. During this interstadial, the Apennines were characterised by warm air temperature and dry conditions that led to the exhaustion of almost all glaciers, and even the disappearance of lakes in proglacial environments. Some small glaciers survived in higher parts of the central Apennines and deposited small frontal moraines. This glacial standstill led to the formation of moraines that became stable around 14.9±0.4ka cal BP (Aquila 1 stade), consistent with a cold episode at the beginning of the Bølling–Allerød. The sedimentation rate of loess of Saharan origin underwent a decrease/interruption, as indicated by the sedimentary records of some lakes. This might indicate a reduction in the advection of southern air masses. As these dust-rich currents were also generally humid, their reduction may have accelerated the already ongoing retreat of the Apennine glaciers.