Illustrative notes of the Geomorphological Map of the Upper Arma Valley (Stura di Demonte Valley, Maritime Alps)

Abstract

The present-day morphology of the upper Arma Valley (Maritime Alps) is the result of the complex interaction among glacial, periglacial, gravitational, running water, anthropogenic, karstic and structural processes. The overall geometry of the valley is related to the main thrusts separating the Briançonnais, Subbriançonnais and Dauphinois Domains. Although most glacial and periglacial processes are no longer active, present-day cryoclast processes, mostly on the southern flanks, are still feeding the numerous gravitational debris-fans, slope talus and debris-flow fans. The reconstructed glaciers that once occupied the Cavera and Serour valleys, likely coeval, gave a similar ELA of about 2100 m asl. Embryonic protalus rock glaciers have been found on almost every northern slope above 1800-2000 m, while other larger rock glaciers have developed from lateral and frontal moraines. Because of the widespread presence of soluble rocks, most of the Valley is characterized by ephemeral channels and other surface karstic features that have developed both on rocks and deposits. The presence of clays, derived from weathered schists, have brought about the formation of badlands, also favored by freeze and thaw processes. Finally, the upper Cavera Valley S-facing flank is widely affected by a complex deep-seated gravitational movement that is responsible for the presence of several trenches along the slope and doubled-crests along the divide.