Geomorphological map of Valnontey (Gran Paradiso Group, Western Alps, Italy)

Abstract

This paper describes the geomorphology of Valnontey (Valle d’Aosta, Graian Alps), located in the heart of the Gran Paradiso National Park in the Western Alps and illustrates the annexed geomorphological map at the scale of 1:15,000. Valnontey retains a relevant heritage of landforms linked to the Pleistocene and Holocene glacial activity, as evidenced by the characteristic Alpine morphology with its typical erosional landforms (U-shaped valleys, glacial cirques, horns, arêtes, trimlines) and well-preserved moraines. A complex system of moraines and glacial deposits outcropping outside the limit of the Little Ice Age (LIA) indicate a Lateglacial advance related to the Younger Dryas cold period (correlable to the Egesen Auct.). Valley and cirque glaciers are the most common and widespread glacier forms. Well-preserved LIA and present-day moraines testify recent glacier fluctuations at the valley head and at the highest elevation, where Valnontey still hosts glaciers that are among the widest and most impressive of the entire Gran Paradiso Group. The Valnontey glaciers have experienced an areal reduction of more than 50% since the LIA, and frontal retreat has further increased since the late 1920s, with a remarkable acceleration of contraction since the end of the 20th century. At present, the processes due to mass wasting, running water, periglacial and nival activities are playing a relevant role in sculpting the landscape. The geomorphological map was realized by using indirect survey techniques based on the photo-interpretative analysis of stereoscopic aerial photographs, digital orthophotos, LiDAR data, and long-lasting geomorphological field surveys. The structure of the legend follows the guidelines suggested by Campobasso & alii (2018). All the collected data were computerized and managed in a GIS environment, in order to build a geomorphological database containing morphogenesis, morphodynamic, morphotype, chronology (where possible), geological structure, and any additional information from other sources. This geomorphological map furnishes a significant tool for contributing to land management, geomorphological risk prevention, and geomorphosite valorization of this wellknown and highly popular valley of the Gran Paradiso National Park.