Last Glacial Maximum and the Gschnitz stadial in the Maritime Alps according to 10Be cosmogenic dating

Two glacial deposits in the Gesso valley (Maritime, Alps) have been 10Be-dated at 20140±1080 (weighted mean±SD) and 16590±970 years, respectively, thus constraining the Last Glacial Maximum (LGM) and Gschnitz stadials in the southwestern part of the Alps. The LGM age is chronologically coherent with MIS 2 and synchronous with most other LGM moraines in the Alps. The Gschnitz stadial also appears to be in agreement with the ages obtained from other Alpine sites and with Heinrich Event I. This suggests that the Alpine glaciers reacted simultaneously and essentially synchronously with the climate change associated with Heinrich Event 1. The Equilibrium Line Altitudes (ELAs) of the LGM and Gschnitz reconstructed palaeoglaciers are 1850 and 1910m a.s.l., respectively. The ELA comparison across the Alps indicates that the palaeoclimate of the Maritime Alps during the LGM was rather different from that of other Alpine sectors. However, the similar Gschnitz ELA value between the Gesso valley and other sites across the mountain chain indicates that Alpine glaciers responded with the same intensity to the climate change associated with Heinrich Event I. Overall, these results suggest that the interaction between the atmospheric circulation of air masses and local Alpine orography was more complex than has previously been argued.