Lithological and Structural Control on Italian Mountain Geoheritage: Opportunities for Tourism, Outdoor and Educational Activities

The Sardinian granitic batholith widely crops out along the eastern side of the island. It was intruded in the poly-deformed and metamorphosed Palaeozoic basement during the Variscan Orogeny, from 350 to 290 Ma BP (Carmignani et al. 2001, Rossi et al. 2009). During this long time period, changes occurred in the geodynamic framework, leading to a great diversity in the structural and compositional characteristics of the various intrusions. Uplift of the Variscan chain provoked the dissection of the granite basement and led to partial erosion of the granite plutons. Later, the Oligo-Miocene anticlockwise rotation movement of the Corso-Sardinian block and the Alpine collision, produced major faulting and tilting in the granite batholith.

The granitic Gallura landscape is characterized by jagged profile reliefs following the major fractures lines, rounded and often isolated landforms, wide depressions, horizontal or gently inclined plateaux determined by tectonics and by the alternation of morphogenetic processes, also in relation to different climate conditions. Along the dense joint network, intense modelling of relief took place, giving the landscape its characteristic features, modelled at a small to medium scale by physical and chemical processes, giving rise to inselbergs, rounded boulders, tors and tafoni (Fig. 2e). The main modelling of the granitic basement occurred during past periods of intense weathering, mainly related to climatic context (Melis et al. 2017). Currently, chemical and physical processes act at a lower intensity, but their activity can be tested inside the cavities within blocks and tafoni, where the granular surface often appears wet and weathered (Fig. 2f).

Granitic relief of the Gallura region has always been strictly interconnected with culture and life of the local communities, giving this area high cultural significance through time. Strong relationships have always occurred between people and granitic landscapes. Resistant building materials, often already available in blocks isolated by the joint network, were of great importance to the local population. Also the impressiveness of the relief (Fig. 2e) has become part of daily life, socio-economic needs and human imagination. Natural cavities have always been a geographic factor accompanying people throughout history, serving as shelters, burial sites or stabling for animals (Fig. 2c).

Peculiar geographical and geomorphological features of Sardinia granitic region offer opportunities for active tourism like climbing (Fig. 2d) and canyoning. One of the advantages is the possibility of practising climbing on granite, all over the year. In particular, specific geomorphological characters of the Sardinian granitic environment allow for outdoor activities like bouldering, on the many rounded blocks resulted from progressive erosion along fractures, and canyoning. The latter is practised along the representative granitic stream valleys, characterising the highest parts of the area and incised in the solid rock. In the Sardinia context, researches focused on methodology to quantify geomorphological hazard on climbing walls (Panizza, Mennella, 2007). These kind of information, like a correct knowledge of the rocks different behaviour towards weathering, could be considered an educational resource with the aim of raising awareness in people on the way to approach to outdoor activities.

Currently some of the Sardinian granitic landscapes are protected and included in official regional lists of protected areas. The inselberg of Monte Pulchiana (Aggius) is the only granitic landform included in the Geosite database of ISPRA.

One of the most representative and well known glacio-karst landscape of the Central Italian Prealps characterizes the Grigne Massif, located on the eastern side of Como Lake. The Triassic Esino carbonatic platforms of the Grigne Massif (Upper Anisian–Ladinian), thrusted along structural planes visible also in the landscape, forms two most important peaks (Grigne): the Northern (2,399 m a.s.l.) and the Southern Grigna (2,181 m a.s.l.). The landscape is typically characterised by karst landforms at different scales: sinkholes, hills and depressions, karren. The past glacial modelling (during the Late Glacial Maximum), mainly exharation, allowed for the formation of glacio-karst landscape, somewhere reworked also by the currently active processes linked with running waters or snow activity, the last one currently effective during a few months in the year (Santilli et al. 2005). The Moncodeno area (Fig. 3a), in particular, is the most famous part of the Massif concerning hypogenic aspects. The deep karst systems formed in the past and successively cut by Quaternary glacial erosion, are famous from a speleological point of view and this kind of activity is common among the amateurs. Among the deepest and most famous caves, there is the Abisso W le Donne (1,160 m deep). In some of these caves, ice is still present and it has been investigated for δ¹⁸O and ionic content relative to depth (Citterio et al. 2004). The ice presence inside the caves represents a peculiar feature, reported firstly by Leonardo Da Vinci. He also represented a particular of the Grigne in a beautiful painting (e.g. Vergine delle rocce, 1483–1486) and in drawings included in the Codice Windsor (e.g. code 12410) adding cultural value to this landscape.

Fig. 3

The Grigne Massif that, moreover, is only 1,5 hours by car from the Milan metropolitan area, is defined by Corti, Anghileri (2003) as a open-air laboratory for styles and ethics in climbing. Indeed, the Grigne Massif, and in particular, the Southern Grigna, represented the object of interest for several generations of climbers who, starting from the second half of the XIX century, equipped hundreds of traditional and alpinist climbing routes. The Ragni della Grignetta Sport Group and School, born after the Second World War, has contributed significantly to the development of alpinism in this calcareous massif. Indeed, this long tradition resulted in 30 equipped rock pillars with routes of different difficulties both for beginners and expert alpinists, where some of the most famous alpinists (e.g. among the others Riccardo Cassin) had herein trained during times. Besides the potential for use deriving from linking Geosciences and sport activity, this feature represents an additional cultural-historical heritage.

The regional geosites catalogue of Lombardia and the interregional list (Various Authors 2008) considered the area for its stratigraphic and glaciokarstic importance. Also the ISPRA catalogue includes the Moncodeno hypogenic system as geosite.

The juxtaposition of contrasting lithologies and geological structures, such as dolomite rocks overlying clayey rock types, undergoing cryoclastic and gravity processes, is responsible for the peculiarity of the Dolomites Massif (Eastern Italian Alps). In 2009 UNESCO recognised 9 different mountain systems, contained in an approximately 142.000 hectares, as a serial property to be included in the World Heritage List (Giannolla et al. 2009, Soldati 2010). Besides their universally recognised outstanding aesthetic value, the Dolomites are a site of exceptional scientific value from a geological-stratigraphic and geomorphological viewpoint. The geomorphology of this mountain range is the result of different morphogenetic agents that have acted in shaping the landscape through time. Tectonics has strongly affected the sedimentary sequences of limestones and dolomites, generating large synclines and anticlines. Monoclinal reliefs are also a distinctive feature. Depending on the lithology, different litho-structural landforms have developed: dolomitic outcrops have been highly fractured under tectonic pressure, developing large and deep valleys that cut through the massifs, and a dense network of several fracture systems, that amplify cryogenic processes. Limestones have been mainly subject to karst processes that have created wide surfaces sculptured by karren (mainly solution runnels and toothed blades), especially on the top of structural surfaces of strata, but also on roches moutonnées and on landslide blocks. Valley glaciers, which have repeatedly occupied the area starting from the Pleistocene, have left their clear signs with frontal moraines, scattered drift, roches moutonnées, glacial lakes and depressions of glacial erosion, the latter reshaped most of the times by karst action. The most common and widespread Quaternary deposits in the area are talus cones and talus slopes, located at the base of dolomite cliffs and on the top of the mountain groups. Important phenomena are landslides of different type and size related to the indirect effect of glacier retreat combined with the lithological, stratigraphic and tectonic conditions of the mountain range.

This area, besides its outstanding scientific and educational value, has important additional values. The aesthetic value is mainly linked with verticality, variety of forms, monumentality and colour contrasts, and it is also responsible for the socio-economic interest in the landforms. In fact, the Dolomites are one of the most attractive mountainous areas in the world, enjoyed by thousands of visitors every year (Gianolla et al. 2009). The dense network of climbing and hiking paths, developed during the last decades, makes this range one of Europe’s most complete and varied destinations for mountaineers and climbers (Panizza 2009, Soldati 2010, Marchetti et al. 2017). Dolomites are particularly famous for providing some of the longest traditional multi-pitch and sport climbing routes in the world. Moreover, several hiking trails and fixed-rope routes, ranging from easy to demanding, are offered as well. These peaks, hosting about 170 historic vie ferrate, has the highest concentration of this kind of routes in the world. The majority of these climbing routes, now popular tourist attraction, were equipped by both the Italian and the Austro-Hungarian armies, to defend key position during the First World War (Rushforth 2014). Concerning the cultural value, in art, both in painting and photography, as well as in poetry, music and others arts, the shape of these mountains has inspired many visions (Panizza, Piacente 2017).

Supramonte is one of the most important karst areas in Sardinia, with high naturalistic and historical value recognized at national level. It is a carbonate massif covering a surface of 170 km² and constituted by dolostones and limestones of Middle Jurassic-Upper Cretaceous age. The carbonatic cover lies on the peneplained Variscan metamorphic and granite basement (Carmignani et al. 2001). The metamorphic rocks prevalently crop out along the western and south-western borders of the Supramonte while granites characterise most of the entire eastern border.

The Supramonte area covers a range of landscapes that goes from the characteristic eastern rocky coast to the inland mountainous relief towards the west, reaching heights of more than 1,000 m a.s.l. (Mt. Corrasi, 1,463 m a.s.l.). Intense karst processes have generated spectacular hypo- and epigenic landforms and have developed, mainly controlled by tectonics, during the Eocene, with the emersion of the Mesozoic sediments, during the Oligo-Miocene tectonic phases, and in the course of Middle Pleistocene in more wet and warm interglacial periods. The karst processes are still active, but the more intense phases and deepening of many canyons characterizing the surface hydrographic system, took place with the beginning of the Mio-Pliocene sea regression, about 5 M years BP (Antonioli, Ferranti 1992).

Supramonte as a whole constitutes a unique landscape unit in which natural aspects largely overrule the human imprint on the environment and its great naturalistic value has been recognised at a national level. The area was inserted in the National Park of Gennargentu, legally defined but unfortunately never put into practice.

Nowadays, Supramonte is a mountainous uninhabited region bordered by small villages. Nevertheless, many signs of past and recent human presence are found all around the region. The archaeological research discovered traces of ancient settlements going back to the Upper Paleolithic. Among the many sites of interest, many caves can be mentioned: Sa Oche, Corbeddu, Tiscali. Witnesses of Nuragic Age settlements are the rests of several towers spread all over the territory. Due to the geomorphological character of the area, traditional use of land and soil is mainly pastoral. Many sheepfolds are present, some of them still utilized, others restored for tourism; they are originally made of calcareous stones, covered with juniper and used seasonally by shepherds. The very known value of the region, both from a cultural and from an environmental point of view, is increased by the concentration of underground and surface landforms of high scientific significance and connected with karst processes. The Supramonte karst area includes some of the most important underground systems in Italy, like the one of Codula Illune. The fluviokarstic net of the Supramonte massif is characterised by deep and narrow canyons (Fig. 3c, d); the runoff waters draining the calcareous massif are diffusely captured along the streams by several sinkholes and return to the surface in a series of springs (Cabras et al. 2008). The drainage pattern is probably inherited from wetter and warmer periods and it is strongly guided by tectonics.

The rich diversity of surface and subterranean landforms and the quite wilderness of the whole area, make it a strong call for the lovers of the active tourism and of some extreme sports. The harsh rocky relief and high vertical cliffs, controlled by tectonics and lithology, are widely known and frequented by climbers from all over the world during all the year. A multipitch and very difficult route (Hotel Supramonte), very famous all over the world and located in the Gola di Gorroppu, was opened in 1999 and the name was assigned taking inspiration from the song of one of the most appreciated Italian artist (Fabrizio De Andrè).

Along the many gorges, canyoning outdoor activity is largely practised. The prevalent underground water flows, and the climate, make this area suitable for canyoning during quite all seasons of the year. Several guide books concerning canyoning and climbing in this area of Sardinia are published and frequently re-edited and updated.

Many of the underground and surface forms of this territory undergo different kinds of regional protection. The Supramonte of Oliena, Orgosolo e Urzulei – Su Suercone, for example, is one of the Sardinian Rete Natura 2000 Sites. We find some of the most spectacular surface and underground landforms also in ISPRA geosites catalogue.

The Pietra di Bismantova is a wide biocalcarenite rock slab overlying marls and clay shales, and represents an iconic landmark of the National Park of the Tuscan-Emilia Apennine (Conti, Tosatti 1994). This unique morphologic feature in the Emilia Apennines encompasses significant scientific, cultural s.l. and socio-economic values. The general morphology of this area is strongly conditioned by lithology, stratigraphy and tectonics and consequently by differential erosion on outcropping formations. The Pietra di Bismantova is a representative example of a mesa. The summit level surface of this rhombohedral-shaped calcarenite rocky slab is due to high resistance of caprock. It is bordered by sub-vertical cliffs, pervasively affected by systems of vertical joints and intensively remodelled by ongoing degradation processes (Fig. 4a). Intense jointing, severe weathering processes, that affect the rock slopes since the end of the last glaciation (GSUE 1976), and high relief energy have favoured the onset of almost all landslide types in the area (Borgatti, Tosatti 2010). Particularly hazardous, in terms of velocity, are rock-falls, the last one occurred in February 2015, posing serious problems for the conservation of this geosite and for the safety of visitors, settlements and infrastructure.

Fig. 4

From a cultural point of view, the Pietra di Bismantova and its surroundings have received high degree of attention since long time ago and remains of early human settlements are dated back to the late Bronze Age and early Iron Age. The verticality and monumentality of this slab, clearly visible even from plain, have inspired many artists through the centuries. The Dante’s description of his ascent to the mount of Purgatory, compared to the trail going up the Pietra di Bismantova, can be quoted as an example. The Pietra is also characterised by high value for the history of alpinism: the first ascent is dated 1922 along the path called Via degli Svizzeri (Motta et al. 2009). Nowadays the site is one of the highly appreciated popular and challenging rock climbing routes of the Emilia Apennines, as confirmed by the organization of climbing competitions, which draws top climbers from all over northern Italy and beyond. In total there are around 250 routes extending for 130 meters from bottom to top, both for beginners and expert climbers. Here there are some long bolted multi-pitch climbing routes of which, the majority extend between 100 to 150 m of length. Several are also the single pitch sport routes. In order to increase the safety of this world-famous tourist area, analysis and modelling of possible rock fall trajectories have been recently developed (Migliazza, Giani 2005, Borgatti, Tosatti 2010). Moreover, a monitoring system has been put in place and detailed studies for the quantitative hazard and risk assessment and zonation of the whole area is being carried out (Corsini et al. 2016).

The Pietra di Bismantova is part of the territory of the National Park of the Tuscan-Emilia Apennines and its importance as geosite is recognised at national and regional level, being listed in both the ISPRA and Emilia-Romagna region geosite lists.

The Orcia Valley is one of the Italian sites inserted in the UNESCO World Heritage List due mainly to its cultural value. It is located in the Siena Province (Central Apennines). Inside this area, clayey outcrops, related to the Pliocene marine transgression phases, are predominant. They are modelled generating spectacular calanchi landscape (Fig. 4b). Locally, the witnesses of the widespread Quaternary volcanic activity, related to the Monte Amiata volcanic complex, are represented by upstanding landforms like the Radicofani neck. It is a more resistant relief in respect to the surroundings clays and it is characterized, at the base of the slopes, by deposits related to rock-falls and lateral spreading processes. On the neck, a castle and a village were built. This kind of human settlements adds a cultural value to the Radicofani area. The village and the castle dominate from above the surrounding landscapes characterized by calanchi (Fig. 4b). The water runoff, since recent times, is leaving space to the action of gravity as testified by the development of shallow landslides. This reflects the interplay with human settlements and land use policies that may influence soil erosion rates (Aucelli et al. 2016). Since this landform transformation across times (from gullies to shallow landslides; Fig. 4b) is very evident, the educational and geodiversity value of the site is high. Moreover, in the area specific researches on the ecologic support role of these morphologies were performed in term of presence of endemic species (Maccherini et al. 1998) and response of arboreal vegetation to stress induced by intense erosion (Bollati et al. 2016a).

The Orcia valley includes geosites inserted in the ISPRA database and representative of erosion processes but the Radicofani area is not considered, even if particularly relevant (Bollati et al. 2016a).

Ophiolitic green coloured rocks associated with deep-sea sedimentary rocks, the latter less resistant to erosion, offer unique and impressive mountain landscapes in Northern Apennines (case study I, K Fig. 1; Fig. 4c and 4f). In this context, the differential erosion between ophiolites and softer sediments is particularly evident. The stability and difficult accessibility of the ophiolitic ridges favoured the presence of human settlements and strongholds, as they could be easily defended. This can be deduced from some local place names: petrum (Pietramogolana) or saxum (Sassomorello); rauca or roca (Roccaprebalza, Roccamurata); or, finally, castrum after castle or fort (Sasso di Castro). The Rio Ceno valley, in the province of Parma, is a still unspoiled environment, dominated by medieval castles and military forts, most of them rising on top of ophiolitic cliffs. Among these, the Castle of Bardi (case study I Fig. 1; Fig. 4c) is worthy of note: strategically placed on a rise made up of basalts and red jaspers, it is still a lofty stronghold at the junction of roads linking the Ligurian western coast to Via Emilia (Bertacchini et al. 2002).

Where the ultramafic rocks outcrop as elongated stripes, superficial modelling generates peculiar mountain shapes like extended ridges. This kind of rocks, undergoing typical weathering that favours the development of a red coloured patina, supports impressive landscapes in both the Alps and the Apennines. In the Alpine context, an evident example is represented by the ridge of the Terra Rossa ridge (case study J, Fig. 1; Fig. 4e), whose place name derives from the peculiar colours due to weathering of ultramafic rocks. It is located in the territory of the Veglia-Devero Natural Park, in the Western Italian Alps at the border between Switzerland and Italy. Nevertheless, it is not inserted in any of the geosite catalogues covering the Italian territory. Another famous ridge constituted by ophiolites in the Northern Apennines is the Pietra Parcellara ridge, in Emilia Romagna (case study K, Fig. 1; Fig. 4f). Within the hydrographic basin of the Trebbia River, where the Pietra Parcellara site is located, fluvial morphologies are strictly controlled by the alternating lithologies (Pellegrini, Vercesi 2017), changing in a few kilometres, becoming very peculiar from the educational point of view (Bollati et al. 2011): e.g. entrenched meanders in correspondence of the Ponte Barberino ophiolitic spur transform to braided and sinuous patterns where clays prevail.

Chemical composition of serpentinite outcropping at Pietra Parcellara allows for the colonization of an endemic flora (Vercesi et al. 2005), underlining its high ecological support role. Indeed, a special Natural Reserve was set in the area in virtue of this peculiar vegetation and the site is listed in both the ISPRA and Emilia-Romagna region geosite lists.

Serpentinoschists outcrops are scattered inside mountain chains and the recurrence of related climbing walls is rare. A spot located in the Central Italian Alps has been selected as very representative (case study L, Fig. 1; Fig. 4d). It is the Sasso del Drago – Drake Spur (Chiavenna Valley, Central Italian Alps). It has an evocative name, as it often happens in the case of serpentinoschists rocky cliffs, and as mentioned before, this is one of the rare examples where climbing activity is practiced. The climbing spot is very accessible and it offers the possibility of climbing on several routes of different difficulty. The lower portion is constituted by ultramafic rocks (Fig. 4d) of the Chiavenna Ophiolitic Complex that are folded within the gneiss of the Tambò Nappe (Pennidic Domain). In this lower portion of the climbing wall, climbing routes are suitable for beginners, while in the upper and northern portion of the climbing wall, where it is incipient the presence of gneisses, routes present higher difficulty. This spot, even if it is not considered as geosite in any catalogue, represents a good and rare site for getting in touch with geology and geomorphology of rocks of oceanic origin through an outdoor activity.