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.

Detailed geological mapping in mountain areas using an unmanned aerial vehicle: application to the Rodoretto Valley, NW Italian Alps

“…The case study was a glacial valley with steep rocky mountain sides and a wide flat valley floor covered with subglacial and supraglacial sediments. The gravitational phenomena involving this area are clear from many gravitational elements, such as fractures, minor scarps and trenches (Forno et al 2012). The produced slope map covers a sector of the left slope (northern area in Figure 7) and the wide valley floor (southern area in Figure 7).…”

“…Finally, the use of a solid (true) Orthophoto (Forno et al 2012) provides a complete 3-D land data interface and a correct aerial photographic perspective in a geo-referenced form, which on site, during the survey, were very useful (Forno et al 2011). Geologists unskilled in geomatics have efficiently used these new instruments during field surveys.…”

Object-Based Geomorphological Mapping: Application on an Alpine Deep-Seated Gravitational Slope Deformation Contest (Germanasca Valley, Western Alps—Italy)

“…In the application area of the OBM, traditional field work involving a detailed geological survey produced by the authors led to good knowledge of the territory regarding the features of bedrock and Quaternary sediments, resulting in a detailed geological and geomorphological map [8][9][10][11]. A detailed traditional geomorphological survey, especially emphasizing the typical gravitational landforms of DSGSD (as minor scarps, trenches, counterscarps and doubled ridges) has been coupled in the investigated area with geomatics techniques to also study inaccessible sectors [3].…”

Applied Geology

“…In the past years, several authors (Forno et al 2011;Forno et al 2012;Piras et al 2016) have conducted detailed survey, identifying the geological and geomorphological characters and resulting in the production of a new morphological and quaternary geological map of the area. A lot of peculiar morphologies connected to deep-seated gravitational slope deformations (DSGSDs) phenomena as scarps, depressions, transversal trenches and ridges elongated parallel to watersheds have been recognized and described in Forno et al (2011).…”

“…In addition, some water mountain sources, many of which potentially exploitable for drinking purposes, have been identified along the longitudinal trenches mapped in the upper sector of Rodoretto Valley: by mean exclusive geological investigations, it was, therefore, possible to demonstrate how the pattern of the hydrographic network is strongly affected by the recognized gravitational features (Forno et al 2012).…”