OROMBELLI G.
Il ghiacciaio del Ruitor (Valle d’Aosta) nella piccola età glaciale – The Ruitor glacier (Aosta Valley) during the Little Ice Age
Pages 239-251
Abstract
The maximum extent reached by the Ruitor glacier during the Lit tle Ice Age (LIA) was recons tructed on the basis of a geomorphologic survey of marginal moraines , dr ift limits and erosional tr imlines. At the LIA maximum the glacier was 27% larger than now (1991) and its terminus was at an altitude 370 m lower than the present. LIA melt -water streams and marginal lakes were identified. In particular the ice dammed Ruitor lake is well documented by shore lines, a delta moraine and by melt-water chan nels. jokulhaup coarse sedime nts have been observed just out of the max LIA morai nes, possibly depos ited by the last outburst (175 1) from the ice dammed lake. On the base of historical documents the max LIA advance occurred between 1751 and 1864, possibly in phase with the 1820 advance shown by other Aost a valley glaciers, as previous ly suggested by Sacco. Pre -LIA Holocene moraines were also observed and preliminarily dated. The surface extent variations of the Ruitor glacier during the Ho locene are bracketed between the maximum LIA and the minimum pre-Neoglacial, inferred from stratig raphic evidence. The Equilibri um Line Altitude variation was of about 150 m, a value in agreeme nt with what observed in other Italian glaciers with a prevailing northern aspect.