Morphological Features of Rodoretto Valley Deep-Seated Gravitational Slope Deformations

Abstract

A new, detailed survey of the Rodoretto Valley (Western Alps, Italy) has been conducted resulting in the production of a new morphological and quaternary geological map of the area. The authors used the innovative Solid (True) Ortho-Photo (STOP) technology integrated with navigation sensors (Global Navigation Satellite System-GNSS/Inertial Measurement Unit-IMU). This state-of-the-art procedure has demonstrated several operational advantages during both the land survey and the post-processing phases. The survey highlighted remarkable glacial evidences and landforms probably connected with Deep-Seated Gravitational Slope Deformations (DSGSDs) phenomena. The glacial forms which have been detected consist of diffuse relics of cirques, glacial slopes, small lateral and frontal moraines and some outwash incisions. The deposits associated with the relics are lodgment till, flowtill and outwash sediments, respectively. The gravitational evidences and the very fractured bedrock that has been recognized on both sides of the Rodoretto Valley, suggest the presence of two DSGSDs which are confirmed also by the occurrence of some doubled ridges in the higher elevation band of the slopes. Moreover, several minor scarps and many longitudinal and transversal trenches, of various size, occur in the intermediate band. Extended landslide bodies have been recognized in the lower altimetric band. The major new geological element detected and interpreted after the survey and the map production is represented by the identification of a well defined WNW-ESE trend of fractured rocks and gravitational landforms. The observed fractures are not limited to the Rodoretto Valley, suggesting the possible connection of the described gravitational landforms with a tectonic discontinuity with the same WNW-ESE trend. This tectonic discontinuity crosses the Cenischia-Nizza System in a zone highlighted by a portion of intensively fractured rocks.