The Italian mountains: glacial landforms prior to the Last Glacial Maximum

The glacial landforms formed before the Last Glacial Maximum (LGM) in the mountains of the Italian Peninsula are discussed. Although the chronological data are still limited, some modern research outcomes from the central sector of the Apennines have led to an accepted glacial chronology. It is now evident that five pre–Last Glacial Cycle (LGC) cold phases and one pre–Last Glacial Maximum cold phase have affected mountain geomorphology, leading to proglacial lakes formation and glaciofluvial depositions. However, only in some cases, there is clear evidence of moraines that have formed during these periods of climatic recrudescence.

Uranium-series dating (230Th/14U) and archaeological artefacts found in aeolian covers made it possible to chronologically constrain at Marine Isotope Stage 6 (MIS 6) some moraines in the Central Apennines. Morphostratigraphical considerations were used to propose a pre-LGM (MIS 3–4) age of other moraines in the same area, as well in other sectors of the Central Apennines. These assumptions have been confirmed locally by the covering of moraines by a tephra layer dated at about 36 ka.

Although analysis of the growth rate of speleothems points to a probable pre-LGM (MIS 3–4) glacial covering in sectors of the Northern Apennines (e.g., Apuan Alps), no ages for the several moraines are available and hypotheses are still based on a morphostratigraphic approach. To date, no glacial traces considered older than the LGM are documented in the Southern Apennines.

Despite a paucity of chronological data, the 1970s hypothesis that the pre-LGM glaciations in the mountains of the peninsula were more extensive is confirmed.