LOCAL GLACIERS IN THE JULIAN PREALPS (NE ITALY) DURING THE LAST GLACIAL MAXIMUM

Abstract

The prealpine range of the eastern Southern Alps includes many high-elevation (up to 1900 m) massifs, whose northern slopes contain glacial deposits. On the northern side of the Chiampon-Cuel di Lanis ridge (Julian Prealps) five different mountain moraine systems are sited; these are related to local glaciers, which were independent from the major Tagliamento Glacier during the Last Glacial Maximum (LGM). Their length was slightly more than 3 km, with lateral moraines developed along the lower part of the deep valleys. Their terminal moraines occur from 490 m to 650 m a.s.l. Clast petrography of the carbonate-rich till clearly establishes a local provenance, distinct from that of the Tagliamento catchment. Inferences from geomorphological parameters, such as elevations of the valley floor and of the lateral moraines, as well as the extent of the accumulation area, indicate a thickness of the glaciers, ranging from 130 to 230 m in the accumulation areas. Application of the Altitude x Area Balance-Ratio (AABR) formula provides an ELA estimate of 1130 to 1200 m a.s.l. This is in agreement with the atmospheric circulation models of the LGM for the Eastern Alps, which indicate an ELA depression, below 1300 m a.s.l., related to higher precipitation rates than the rest of the Alpine chain.