Description
The Camerona enters eastwards in an ascending trend and with a moderate slope (15°- 20°) for about 60-70 metres, always very wide (18 to 25 metres wide, in plan) and with a ceiling about ten metres high, which only in the innermost part descends noticeably. In the main section, the cavern has no branches or side passages. The floor is completely occupied by large blocks of rock often represented by tabular fragments of the fallen layers from the vault, with a diameter of 1-3 m, while the thickness is generally between 0.5 and 1.5 m and the upper and lower faces are planar and sub-parallel. At the end of the cave, the blocks are progressively covered and concealed by a centimetric to decimetre thick layer of reddish-pink calcareous silt from the innermost parts of the cavity. These are sediments of probably mixed origin, originating both from the runoff of glacial deposits scattered along the slope above, and residual soils, i.e. derived from the unresolved fractions produced by the karstification processes of the limestone rock, which have been flowed, transported and redeposited by percolating waters.
Inside the cavity, at the time of the last visit (first ten days of March 2008), a modest diffuse dripping from the ceiling was observed, especially in the intermediate and final part. Other signs of water, mostly modest, were limited to small pools of concretion ('gours') and weak water run-off on the walls and surface of the deposit lining the steep final section of the cave. In this area, a conspicuous bank of beige-coloured calcareous silt was massively deposited, apparently devoid of laminar accretion structures, of medium consistency and relatively friable. The first explorers of the Camerona etched the deposit with marked footprints in order to facilitate the ascent, which is inclined at an angle of about 45°, and to find any other continuations at the top of the ramp.
The first part of the cave has no concretionary forms on the ceiling or walls. The central sector of the ceiling consists of the basal part of a stratification plane that gradually dips towards the north-west. In the innermost part, on the other hand, the ceiling is covered for large sections with large mamelon concretions, 0.5-1.0 m in diameter and 1.5-2 m long. These are stubby, 'pine-cone' stalactites, i.e. intermediate forms between stalactites and concretional flows, in which the radial growth is considerable, comparable to or slightly less than the vertical growth. On the floor, on the other hand, in correspondence with the concretions described above and the areas of dripstones, embryonic stalagmite forms are observed, more similar to concretionary volcanics, ring-shaped, of modest height (4-10 cm) and thickness of the order of 5-15 cm, brown in colour.
Finally, at the base of the steep terminal slope, there are some modest basins ('gours') with a diameter of 20-30 cm and a depth of a few centimetres. When the water meets a small asperity, it deposits its content of calcium carbonate, forming modest ribbons of concretion that gradually increase until they form veritable embankments, sometimes with a sinuous or curved course. The continuous deposition of calcium carbonate can even exceed one metre in height (as for example in the Grotta del Calgeron in Valsugana). In the Camerona, on the other hand, the pools are still in an embryonic stage, poorly developed and only recognisable to the expert eye.
The side walls of the cave, which are darkly coloured in places, are characterised by the presence of diffuse honeycombs on the rock surfaces. These are small concavities with a diameter of 1-3 cm and a depth of 0.5-1.5 cm, with a rounded bottom, separated by thin, sharp ridges. These morphologies are probably linked to phytokarstism, i.e. the action of chemical solution by organic acids released by certain species of algae or lichens that frequently develop in damp environments, with little light (the considerable size of the entrance to the Camerona allows light to faintly illuminate the tunnel for the first fifty metres), on vertical calcareous rocks traversed by weak veils of water with a sub-neutral or basic pH, even though they are poor in organic substance.
The environment, vegetation, climate, geology
The slope along which the access path to the cavity develops presents in the initial part some modest outcrops of well-stratified rock, while in the intermediate and terminal part of the access path it is characterised by a vast accumulation of landslide blocks of considerable size, in some cases exceeding 10-20 m in height. The blocks, which show signs of colonisation by mosses, lichens and minor vegetation, are part of one of the many landslides from the Quaternary period that marked the Trentino valleys after the withdrawal of the last glaciation.
The vegetation that covers the slope is a mixed forest, mainly consisting of beech and fir trees.
The cave opens in the limestone formation known as the 'Misone Limestone' of the Lower Jurassic (Age: Sinemurian - Pliensbachian), which can be dated to approximately 190 - 200 million years ago. In recent years, the area has been the subject of geological studies and surveys as part of the CARG (Cartografia Geologica Regionale - Regional Geological Mapping) project, which led to the edition of the new 1:50,000 scale geological map "Foglio 080 Riva del Garda".
From a structural point of view, the western flank of Monte Misone constitutes a monocline plunging west-northwestwards, interrupted by a number of parallel, sub-vertical, slightly transverse faults. The monocline connects towards the north-west to a complex tectonic junction zone, consisting partly of a syncline (towards the north) and partly of adjacent rocky sectors interrupted by sub-vertical faults, with an axis almost coinciding with the valley floor of the Ballino area, formed by more recent calcareous-marly rocks (cretaceous formations called 'Maiolica' and 'Scaglia Rossa'). The monoclinal tectonic structure interrupted by faults on the western slope of Monte Misone, described above, accounts for the presence of 50-60 metre high rock walls, set along the left-hand transcurrent faults, oriented in such a way as to form some characteristic steps placed in succession that interrupt the mountainside. These are therefore forms of structural origin, linked to tectonic control, and not morphologies attributable to erosional events, such as ancient valley incisions, as might appear at first glance.
The outer surfaces of the rock in which the cave opens are grey in colour because they are covered by patinas or barks of surface alteration and decalcification caused by the action of exogenous agents. The rock, which can be classified as a micrite (microcrystalline calcite), is light grey to very light hazelnut in colour when freshly fractured and, when observed with a magnifying glass, sometimes shows the presence of original structures reduced to 'ghosts'; these are probably oolites, 'lumps' (irregular aggregates of larger dimensions), intraclasts and bioclasts whose contours are very evanescent due to diagenetic processes of calcite recrystallisation.
In the innermost parts of the cave, samples of light grey to whitish limestone were also collected in thin layers (10-12 cm thick) interspersed in the Misone Limestone, with significant silica content of organic origin disseminated in the matrix, deriving from the remains of sponge spicules and radiolarians; these are probably lithotypes that herald the transition to higher rock formations (Tofino Formation - Bocchetta Slavazzi Member; Middle Jurassic).
From a hydrographic point of view, the area is characterised by the presence of a few mostly temporary streams. To the west of Ballino, on the eastern flank of the Dosso d'Enziana - Cogorna ridge, several sub-parallel tributaries develop at Coste Lindos, Raina and Tovaros, which on the valley floor form several debris-flow conoids that are currently inactive or can only be reactivated in the event of catastrophic flood events. The most important of these is the Rio Ruzza, which forms the alluvial deposit on which the village of Ballino stands and then continues along the valley floor southwards, towards Tenno. On the western slope of Monte Misone, just north of the cave, some temporary streams can still be found in the Cercena and Stavei localities.
As far as the current climatic regime of the area is concerned, we must refer to the weather stations closest to our area of interest, represented by Cavrasto and Tenno. For the Tenno area (428 m altitude), the data shows a certain variability (ranging from 1162 mm in 1975, to 840 mm in 1988). In the period 1921-1950 at Cavrasto (Bleggio - 712 m altitude) an annual average of 1298 mm was obtained. For the Ballino area, bibliographic data, again for the period 1921-1950, gives an average of approximately 1080 mm/year. In the present day, the Ballino area is therefore characterised by a transitional climate between the temperate oceanic type, without a real dry season, and the continental type. More specifically, the climate is of the pre-alpine type, with two rainfall highs in spring and autumn and two lows in summer and winter. In reality, a relative minimum can be identified in summer, but a certain degree of rainfall is never lacking, always approximately between 80 and 100 mm/month for the months of July and August.
The temperature data available for the current period refer only to the Tenno station (altitude 428 m above sea level) for the years ranging from 2000 to 2007 and show minimum values indicatively between -4.6 and -4.9 °C (January) and between 19 and 23° C (July and August); the maximum values are instead between 0.3 and 3 °C (January) and between 22 and 30° C (July and August). For the Ballino area, a temperature decrease factor must be taken into account due to the higher altitude (753 m asl for the town centre and 893 m asl for the cave). The average annual temperature is most likely between 8.6 and 9.0 °C.
The size of the Camerona is naturally not compatible with the smallness of the present-day reservoir, and the formation of the cave dates back to much older times. In agreement with many other karstic complexes in the southern Veneto Alps, it was probably located in the Oligocene, shortly after the territory emerged from the sea, or at most during the later middle-superior Miocene, with a tropical climate, a particularly intense rainy season and rich vegetation with intense pedogenesis.
During the Quaternary period, glaciations played an important role in the cyclical filling and emptying of the sediments, but should not have particularly influenced the development of the cave. Instead, concreting continued into the more recent Quaternary period in which it can be assumed, in accordance with palaeoclimatic data obtained from isotopic analyses of cave concretions (Borsato, 2007), that there was a humid and very wet climate from the beginning of the Late Glacial period (approximately 11,000 - 12,000 years B.P.) until 8,000 years B.P, followed by a period of progressive reduction in rainfall with evolution towards a dry, cold continental climate in the period between approximately 8,000 and 5,000 years B.P. (= Before Present).
Cave formation
An important role in the formation of the cave was undoubtedly played by the stratification, which here has an inclination of 30-32° with a north-westerly dip (306°). The strata vary in thickness from a minimum of 50-70 cm to a maximum of 130-160 cm, but local intercalations of thin 10-12 cm layers of microcrystalline limestone (micrite) and massive counters more than 2-3 m thick are also visible.
In the initial part, several fractures of significant extension can be observed, which contributed to the formation and growth of the considerable cross-section. The first, with a direction almost orthogonal to the axis of the cave, is visible a short distance from the entrance and plunges north-west at an inclination of about 55°, crossing the entire section of the cavity. A second system of fractures is responsible for the morphology of the right side of the cavity (proceeding inwards), and plunges towards the southwest with an inclination of 82°.
In the second part, the morphology changes. In the last section (about 20-25 metres long), the cave narrows and subsides noticeably (6-7 metres wide by 2 metres high). The floor, formed by silt and concretions, climbs upwards with a considerable slope and the gallery, which almost seems to bend towards the north-northeast, suddenly ends with a small room and two short, barely visible and impassable tunnels at the bottom. In their 1932 surveys of this area, cavers from Rivoli pointed out two small shafts recently dug in the silt and accurately described the sediment coming from the top of the cave during periods of heavy rain. The overall development of the cave is about 100 metres and the difference in height between the entrance and the highest internal point is almost 33 metres.
An initial genetic phase can be traced back to the progressive enlargement of the cross-section of the cavity following the passage of significant amounts of aggressive water along the stratification planes and fracture systems (generally ascribable to a humid tropical climatic phase with tectonic-structural control that favours the absorption of water at depth). Subsequently, the widening and morphology of the tunnel, after the deepening of the valleys and thus of the base level, was completed by alternating phases of filling-emptying of large quantities of sediment (in close dependence on climate variations), collapse and erosion phenomena at the mouth (glacial erosion and exacerbation, slope tension release), alteration of the walls and vault (concreting, cryoclastism, phytokarst), etc.
Hypogean fauna
From 1935 to 1949, various speleo-biologists visited the Camerona and carried out accurate faunal research (Alberto Brasavola de Massa of the Natural Science Museum in Trento, Livio Tamanini of the Rovereto Civic Museum, Leonida Boldori of the Italian Entomological Society, etc.). Among the most important finds, in addition to interesting specimens of molluscs, collemboles, dipterans and myriapods living in the wettest areas of the cavity, the scientific literature reports some rare species of insects (carabid beetles, heteropterous hemipterans) as well as some very small terrestrial isopods (crustaceans) specifically adapted to living in an underground environment.
Historical information, explorations and previous studies
The visibility of the wide entrance from the Ballino area and the fact that the cave is easily accessible within a few minutes, suggest that the cavity has been known and probably frequented since the earliest times.
It is barely mentioned in Cesare Battisti's "Guida delle Giudicarie" (1909), in which the author instead publishes extensive news and photographs of other less important caves such as Arca di Fraporte di Stenico or Bus de la Bastia di Tione.
Twenty years later, in 1932, Italo Maroni and the speleologists of the Gruppo Grotte della SAT di Riva del Garda (SAT Caves Group of Riva del Garda), after having fully explored the cave, drew the first accurate topographical survey of it, accompanying it with some (unpublished) summary observations on the internal morphology, especially of the deepest part.
Arturo Martini dedicates a few lines to the cave in his historical-tourist guidebook "La conca delle Giudicarie Esteriori" (Trento, Saturnia, 1955) in which he generically mentions objects and traces that were found there as proof of its use as a shelter in prehistoric times or as a probable refuge in the Iron Age for groups of Euganean peoples who stopped here during their raids north of Lake Garda. The cave is actually located in an almost strategic position on the side of the pass that connects the Upper Garda with the Giudicarie, and has always been considered historically important for the transit of goods to the port of Riva.
According to recent studies, however, the strategic importance of this route should be reduced in favour of other communication routes such as the Val Lomasona and the Passo di San Giovanni, whose frequentation in proto-historic and historic times is testified by a series of finds distributed along these routes.
A brief description, accompanied by some photographs and the reproduction of the Maroni plan, is given by Gino Tomasi in the first volume of "Le Giudicarie Esteriori" (published in 1987 by the Stenico Industrial Electrical Consortium). Finally, Marco Ischia (SAT speleological group of Arco) published an interesting article with detailed faunistic information in the SAT Yearbook 2001 of Riva del Garda.
Recent archaeological research
Archaeological research in recent times has not revealed any particular finds. Due to its easy visibility and accessibility, the cave has undoubtedly been a frequent destination for improvised researchers who have removed any finds present on the site, with deep reworking of the ground.
It should also be pointed out that according to the archaeological data currently available, the main north-south connection routes in this sector of Trentino in prehistoric and protohistoric times were the San Giovanni Pass and Val Lomasona. The route over the Ballino Pass would therefore have been of secondary importance, and this could probably indicate that the importance of the Camerona as a place of frequentation was also somewhat overestimated.
Main data La Camerona cave
Location: Ballino Pass
Municipality: Fiavé
UTM coordinates - Rome 1940 (National): East 1640827, North 5091774
UTM WGS 84 coordinates: East 640798, North 5091751
Altitude: 893 m asl
Geological Formation: Misone Limestone - Lower Jurassic (Age: Sinemurian-Pliensbachian)
Bibliography
Borsato A., 2007 - Climatic-environmental reconstructions for the Holocene from calcareous tuff and mountain milk in Trentino. In: Studi Trent. Sci. Nat., Acta Geol., 82 (2005): 239-259.
Eccel E. & Saibanti S., 2007-Climatic frameworkof the Lavarone-Vezzena Plateau in the general Trentino context. In: Studi Trent. Sci. Nat., Acta Geol., 82 (2005): 111-121.
Ischia M., 2001 - The "Camerona" Cave near Ballino. In: Yearbook SAT Riva del Garda. 2001
Martini A., 1955 - La conca delle Giudicarie esteriori: guida storico-turistica. - Trento, Saturnia, 1955. 170 p.
Tomasi G.,1987 - Natural aspects of the Giudicarie Esteriori. In: Le Giudicarie Esteriori. Banale, Bleggio, Lomaso. V.2, The territory. Stenico (TN), Consorzio elettrico industriale di Stenico, 1987: 15-81.
Access
It opens with a wide portal to the east of the hamlet of Ballino, just above the village, at an altitude of 893 metres. The cave can be reached starting from the centre of the village and following a small road uphill towards the south-east to the locality of Castil. Here, immediately behind the colony of the Padri Verbiti di Varone (Verbiti Fathers of Varone), a path starts, which was restored in 2006 by the Servizio Foreste e Fauna della P.A.T. (Forestry and Fauna Service of the P.A.T. - Tione Forestry District Office). The path climbs north-east and leads to the cavity in about 15-20 minutes, crossing a slope consisting of an ancient accumulation of landslide blocks. The cave entrance, which is exceptionally large (20 metres wide by 12 metres high), is easily visible from the state road no. 421 and characterises the low western slope of Mount Misone in a special landscape way.
