New geomorphological and chronological constraints for glacial deposits in the Rivoli-Avigliana end-moraine system and the lower Susa Valley (Western Alps, NW Italy)

Our new dataset from the Rivoli-Avigliana end-moraine system, the westernmost amphitheatre of the Italian Alps, provides an important step towards understanding foreland-reaching glaciations before and during the Last Glacial Maximum (LGM) in the Western Alps. Be-10 data from six boulders in pre-LGM deposits gave ages between 26.8 +/- 2.1 and 41.2 +/- 1.9 ka. Based on morphological and pedological data, we interpret the oldest age as a minimum age for the glacier advance(s). Be-10 results suggest that the LGM occurred in two major steps. During the first at 24.0 +/- 1.5 ka, several ridges were constructed demonstrating oscillation of the Dora Riparia glacier snout at the maximum position. Our data demonstrate a significantly larger LGM extent in the Rivoli-Avigliana amphitheatre than shown on previous maps. The maximum advance was followed by a short re-advance of the glacier at 19.6 +/- 0.9 ka, as recorded by Be-10 ages from boulders in lateral positions along the lower Susa Valley. The maximum ice surface during the LGM was at 1000-920m a.s.l. in the final reach of the valley (560-620m of elevation above the alluvial plain) and at 620-340m a.s.l. at the continuous moraines in the amphitheatre.