Climbing crags: an unusual approach for science outreach in the frame of the CARG project

In the Central Alps, the connection between man and mountain has always been an integral part of the culture of local populations. In the past decades the mountainous area of Valchiavenna, Val Masino and Alto Lario has evolved from a place where the main means of subsistence were mountain pastures and woods, into a territory where sports tourism, such as trekking, skiing, alpinism and climbing, has become an important source of income. From the early 1900’s, when mountaineering was an elitist activity, numerous alpine associations have been established, like the Italian Alpine Club (CAI), giving rise to the clustering of alpinists and climbers in large and lively communities. In the 1960’s, Val di Mello (Val Masino) was one of the first places in Italy where the climbing movement known as ‘Nuovo Mattino’ took place. This new fundamental climbing philosophy broke away from classic climbing, that involved extensive use of artificial aids (such as nails, fixed ropes, etc.), definitely embracing the technical difficulty of free-climbing. Nowadays, climbing has become a mainstream sport, and territorial alpine associations provide means and best practices to mountaineers for carefully facing the mountain. Although climbers have the possibility to “put their hands on the rock”, in most cases they are unaware of the surroundings, even if the geological features could affect the climbing style. In the last years, a geological survey has been conducted in the mountainous region of Valchiavenna, Val Masino and Alto Lario, in the frame of the CARG Project (Carta Geologica d’Italia alla scala 1:50.000, geological sheets 038 “Chiavenna”, 021 “Passo dello Spluga”, 022 “Madesimo”, 037 “Bodengo”). The study area is located in the north-western Central Alps, just South of the Italy-Switzerland national border. Here, we can find different poly-metamorphic basements belonging to the Penninic nappe stack outcrop (e.g. Adula, Tambò, and Suretta nappes), divided by slices of metasedimentary cover (e.g. Splugen Zone and Misox Zone) and intruded by Permian and Oligocene metagranitoids and granitoids (e.g. Truzzo Granite, Bergell Pluton and Novate Granite). The nappe stack is juxtaposed by some structural and paleogeographic uncertain units, such as the Chiavenna Unit mafic-ultramafic complex (Schmid et al. 1996). To the South, the Insubric Line separates these tectonic units from the South Alpine metamorphic basement (Tonale Nappe) and its sedimentary series (Upper Orobic Nappe). Even if the main activity of the CARG project is the collection of a complete set of geological and geomorphological data, scientific outreach and activities are a provided legacy of the project, promoting mutual interaction and sharing between the scientific community and the local population. To achieve the latter objective, the selection of intriguing and gripping topics could represent a good approach to stimulate the audience’s attention and curiosity. In this context, local climbing sites can be an unusual but engaging subject (or even place) for scientific outreach, even though the collaboration with the local mountaineering clubs for organization and promotion of activities and meetings. The use of 3D Digital Outcrop Models that employ high resolution photogrammetric and point cloud data from Unmanned Aerial Vehicles, can help to make the topic more accessible and impressive. The possibility to communicate geology with an appealing approach for the population, together with the cultural value that the alpinist community attributed to rock climbing sites over time, as mentioned above, makes to consider climbing crags as geoheritage sites possible [3]. For this reason, we have selected six climbing sites, each one featuring peculiar lithology, geomorphological processes and structural settings. They represent a sample of Valchiavenna, Val Masino and Alto Lario geodiversity, and together they help outlining the geological, structural and geomorphological features of the study area (Fig. 1): - Cimaganda bouldering site is located near the homonymous hamlet, on the left side of Val San Giacomo. The climbing area was formed as a result of a landslide that fell down from the mountain, damming the valley. The landslide body is made up of cyclopean blocks of different lithology, as Truzzo Granite and Tambo Nappe ortho- and para-derived rocks. The instability of the landslide niche and the neighbouring cliffs continues to occur, consequently, regular monitoring is essential to mitigate risks and ensure safe climbing. - The Dalò via ferrata is located on the right flank of Val Bregaglia, above the small village of Pianazzola. It develops on a cliff that is composed of Permian meta-granitoids belonging to the Truzzo Granite intrusive body. The steep walls of the cliff represent the morphological expression of the lithological contrast between the metagranite and the surrounding lithologies (mainly paragneisses and amphibolites of the Tambo Nappe basement). The intrusive body features a high-variable rock texture and grain size. In the less deformed portions the rock is massive and characterized by centimetre-sized K-feldspar phenocrystals, which could be used as holds, while other portions are characterized by fine-grained centimetre- to decimetre-sized mylonitic and ultramylonitic bands that reduce the grip of the rock. - The Uschione climbing area is located on the left flank of Val Bregaglia above the town of Chiavenna and in the core of the Chiavenna Unit, a mafic-ultramafic complex mainly composed of amphibolite (e.g. Fate Nere crag) and peridotite (e.g. Lottano Climb and Olimpo crags), intruded by granitic, aplitic and pegmatitic dykes of the Oligocene Novate Granite (e.g. Sasso Bianco and Tanno crags). Here, the climbing sites are characterized by a frictional style, as the consequence of the subglacial exharation that smoothed the rock outcrops. - The Precipizio di Strem climbing crag is located in Val Bodengo, above the Corte Terza hamlet. Its peculiarity lies in the migmatitic texture of the outcropping rocks, which developed under high-grade metamorphism. Here, the Adula nappe orthogneiss underwent partial melting, segregating the melt into white layers called ‘neosome’ from darker ones of resistant rock called ‘paleosome’. This results in a well-developed network on the cliff where the climbing routes develop, especially in the sector known as ‘Ragnatela’ (Italian word for “spider web”), where the rock's massiveness and the low presence of fractures promote a frictional climbing style. - The Val di Mello climbing area, on the Raethian side of lower Valtellina, is characterized by outcrops of granodiorite belonging to the Oligocene Bergell intrusion. These rocks are also known with the local term ‘Ghiandone’, due to the presence of centimetre-sized phenocrysts of alkali feldspar. As for the Dalò crags, the preferential erosion preserves feldspar crystals and facilitates frictional climbing style. Additionally, holds or even climbing routes may follow rock exfoliation cracks. These features are typical of these kinds of rocks, generally related to weathering processes and to the stresses accumulated or induced within the rocks, even if the processes leading to their formations are complex and still debated. The intersection between different fault families and local cracks promotes the fall of cyclopean blocks, which represent a source of attraction for many boulderers. The most popular one is called ‘Sasso Remenno’, with an impressive volume of more than half a million m3. - Sasso Pelo climbing area develops between Gravedona ed Uniti and Peglio municipalities, in the Alto Lario area, a few kilometres beneath the Insubric Line. The climbing cliff is composed of dolomite that underwent weathering and carbonate dissolution, leading to the formation of karst structures, such as ‘rillen karren’ or ‘alveoli’. These features give more grip for friction climbing. Together, these climbing sites represent the geodiversity of the area and also could represent useful natural outreaches for the many attending climbers. Indeed, geological features are fundamental for the climbing style, since familiarity with the type of rock permits to know the critical issues of the climbing routes and to be more mentally and physically equipped, improving performance. Additionally, the knowledge of ongoing and future transformation processes would contribute to a greater awareness of the hazard and a reduction of personal risks associated with climbing. Recognizing climbing crags as sites for geoscience dissemination and geological heritage promotion can attract greater attention, fostering collaboration between scientists and institutions for their preservation. Highlighting their importance may also encourage public administrations to invest in sustainable management, ensuring accessibility and environmental protection. Scientific outreach can be accessed in various ways: by the installation of explanatory on-site panels; through the use of QR codes; by the participation of expert geologists in field activities organized by local recreational and sports associations; targeted activities with climbing groups. In order to enhance visitor experience by promoting 30 geological knowledge and to recommend a safe climbing practice, as it was experienced, in the past, for the Ministerial strategic project AREE INTERNE "School, mountains and sport: strategies and tools for Earth Sciences teaching and dissemination for the conservation and development of the mountain territory". The initiative involved the use of climbing walls for outside activities and students guided to observe and understand the rock faces while practicing their sporting skills [2].