Geomorfologia dell’alta Val di Genova (Gruppo dell’Adamello, Alpi Centrali)

Geomorphology of the upper Val di Genova (Adamello Group, Central Alps)

Abstract

The Val di Genova is one of the most characteristic valleys of the Adamello Group. It extends up to the Adamello and Lobbia-Fumo summit glaciers, two high plateau glaciers which follow, with their relative effluences, the valleys radiating out from the summit area. Other smaller glaciers and snowfields develop in small cirques and other topographically protected areas. The morphogenetic agents which have been most influential are glacial and periglacial, still active at the glacier edges. There are also landforms and deposits clearly associated with gravity and with the flow of fluvial and fluvioglacial waters, which are active, together with phenomena of debris flow which occurred towards the end of the 19805, in the lower part of the valley. On the basis of morphological, sedimentological, stratigraphic, lichenometric and dendrochronological observations and with the help of several ¹⁴C dates, preminent phases of the geomorphological evolution of the study arca were construcied. The maximum extension in the Holocene of the Vedretta della Lobbia and Vedretta del Mandrone were reconstructed and some moraines associated with different events in the Little Ice Age were dated. In particular, a moraine near M.ga Matarot shows an advance of the Vedretta della Lobbia ascribed to the first phases of the Little Ice Age and dated at around 410 ± 90 years ¹⁴C B.P. (1430-1635 A.D.). Since the middle of the last century there has been a notable regression of the glaciers, broken by brief and not very marked advances, however not always registered accordingly by the main glaciers. The evident contraction of the ice surface has brought about a lowering of the surface of the ice by several tens of meters in the accumulation area and the marked regression of the fronts has caused a withdrawal of more than 2 000 m for the Vedretta della Lobbia and about 1800 m for the Vedretta del Mandrone.