Stage 4 – From Gajum to the Shrine of S. Miro along the first section of the “Giorgio Achermann” Geological Trail and return to Gajum

Description

Walk alongside the Sorgente Hotel and Restaurant. On the left, when entering Via Per San Miro, ERSAF (the Regional Agency for Services to Agriculture and Forestry) installed two explanatory panels for tourists, which introduce, respectively, the Ravella Valley trails and the “Giorgio Achermann” Geological Trail – conceived in the Eighties by the Gruppo Naturalistico della Brianza (Brianza Naturalist Society) and rearranged in 2003, when it was dedicated to the Swiss journalist who founded the Society. There is, too, a Insubria Region Geosites’ totem (which refers to the Malascarpa Sasso mountain above), and an indication to St. Augustine’s Path. Take Via Per San Miro, which is cobbled, keeping to your right; behind the panel with the introduction to the Geological Trail (which starts here) another panel indicates the first geological event, the Coral limestone (Event no. 1), a block of sedimentary rock consisting mainly of fossil remains of corals, coming in particular from branched colonies of Thecosmilia clathrata. This formation, called Zu Limestone by geologists, originated in the late Triassic (approx. 210 million years ago), when the sea was warm, clear and shallow (an ideal habitat for the life of corals), similar to that of the coral reefs existing in tropical and equatorial areas. It is a compact rock, greyish in colour, which is subject to erosion by acidic rainwater (karstism). It forms the eastern slopes of the Cornizzolo and Pianezzo mountains, as well as part of Prasanto. After approx. twenty metres, the asphalt covering the ground is replaced by cobblestones, and you start to walk alongside the Ravella stream. After another 100 metres a panel was installed, on the left of the road, to illustrate the geology of Canzo’s Horns, one of the most complex areas of the Alps from a geological point of view. About 50 metres further along the road another panel, once again on the left, illustrates the phenomenon called “Slumping” (Event no. 2), which affects the sedimentary formation outcropping at the edge of the path, called Moltrasio Limestone (the most common in the Triangolo Lariano, as it dates back to the early Jurassic, approx. 190 million years ago), the layers of which are folded, due to the sliding and folding of the sediments during the consolidation process on a submarine slope, at quite deep levels.

After approx. another 70 metres, on the right, there is a clearing which is the last available parking area; after that the footpath is blocked on the left by a pole and an iron barrier, which show that vehicles cannot pass. It is therefore advisable to keep to the right (please mind the remaining part of the barrier which reaches the right hand-side of the path). A further 60 metres along the path, on the right, just after a clearing with the water system, you meet two other geological places of interest, with the relevant descriptions. The first is a millstone made of a marine sedimentary rock, called Sirone Conglomerate (Event no. 3), better known by the local name of “ceppo”, which derives from the consolidation of material eroded by weathering on land (gravel, sands and silts), carried by the rivers into the sea and deposited at modest depths, about 90 million years ago, in the Cretaceous Age. The second event is a block of Majolica (Event no. 4), a compact white limestone of deep marine sedimentary origin, dating back to 145 million to 135 million years ago, between the end of the late Jurassic and the beginning of the early Cretaceous periods, frequently arising in the southern portion of the Triangolo Lariano, which was used for the production of concrete (Cesana quarry). A little further on, on the right of the path, there is yet another place of interest, i.e. fragments of Metamorphic rocks (Event no. 5), boulders from the Valtellina and Chiavenna, transported by glaciers during the Pleistocene glacial stages and abandoned as they drew back. In the Ravella Valley you can find mica-schists and gneisses of the Alpine basement, oriented texture rocks – mainly quartz, mica and clear feldspar – and the Valmalenco serpentinites, so called because their appearance resembles snake skin (snake is “serpente” in Italian). Along the trail you can see several blocks of neatly squared serpentinite: in fact, before the Second World War, some companies “extracted” this material for building activities, cutting off these blocks almost exclusively by hand in the place where they were found, with the aid of saws and chisels.

About 10 metres further up the path, on the right, you can see a large serpentinite boulder, of approximately 3 x 3 metres, beyond which the right edge is not protected anymore: we advise you to keep to your left. After another 10 metres, a sign on the left indicates the Marine sedimentary rocks (Event no. 6), the most widespread in the Triangolo Lariano, including, in particular, the Moltrasio Limestone, which presents itself in the shape of grey-whitish coloured banks of stratified limestone and marly limestone. This rock, formed on the bottom of the ancient sea that occupied this area during the early Jurassic (about 202-180 million years ago), surfaced at a later stage following the movements of the earth’s crust during the formation of the Prealps and Alps. Other examples of marine sedimentary rocks, the Flints (Event no. 7), can be seen on your left, after approx. 60 metres: siliceous, hard and compact, of glassy appearance and varied in colour (brown, black or red), they were formed by the remains of the outer silica shell of Protozoa (Radiolaria), Sponges and Algae (Diatoms). They are often present in thin layers, lenses or nodules included in limestone rock; for their toughness and easy workability they were used by primitive men for the manufacture of tools such as gravers, scrapers, spear points and arrows. Footpath number 7, which heads to Mount Cornizzolo, begins a little further on, on the right. Continuing along the Geological Trail, on the right, you will come across the panel that describes another sedimentary rock which appears now and then in the southern portion of the Triangolo Lariano: the Lombard Red Ammonitic Limestone (Event no. 8) of limestone-marly marine sedimentary origin, interspersed with flint layers and lenses, dating back to the early Jurassic Era (about 190 million years ago). Reddish in colour, it is rich in fossils, especially Ammonites, i.e. Cephalopod Molluscs with planespiral shells, extinct at the end of the Mesozoic era.

Continue for about 50 metres, cross a 15 metre long bridge over the Ravella stream (with approx. 120 cm high abutments consisting of wooden railings), followed, 150 metres away, by another bridge having the same characteristics. We are immersed in a mixed mesophilous wood, with European ash, sycamore, lime trees, and laburnum (golden chain trees). After 100 metres, on the left, you come across a boulder from high Valsassina (in the Maglio area), consisting of Verrucano Lombardo (Event no. 9), a compact conglomerate, reddish in colour, made of porphyry and quartz pebbles. It is a continental sedimentary rock, formed in sub-desert climate, dating from the late Permian period (the last period of the Paleozoic or Primary Era, about 260 million years ago). From this point onwards the surface of the trail becomes a little more uneven. At a short distance you find a signpost signalling station 10 (“The people of the stream”) of another themed walking trail that winds through the Ravella Valley, the “Spaccasassi Trail”, designed and set up by the Regional Forestry Agency with funding from the Provincial Authority of Como. Right next to it there is another panel installed by ERSAF illustrating the biology of the European Freshwater Crayfish, an important “inhabitant” of the stream, which was recently the subject of a LIFE Nature project. After crossing yet another bridge on the Ravella stream (with the same characteristics as the two above), the climb becomes steeper, and, after 60 metres, you will see a “Ghiandone” boulder of on the right (Event no. 10), coming from the Masino Valley. It is a granodiorite, which takes its name from the presence of large crystals of white-pink potassium feldspar, sub-rectangular in shape, similar to acorns. After about forty metres turn right into the steep cobbled footpath that leads to the Shrine of S. Miro, following signal no. 6 to Mount Cornizzolo. By walking straight on and crossing the wooden bridge on the Ravella you continue to cover the second section of the “Geological Trail” up to Terz’Alpe, entering the “Canzo’s Horns” Regional Forest. Having taken the deviation to the Shrine instead, after approx. sixty metres, on the left, on a rock at the edge of the path, you may notice a small chapel that bears the date 1818 engraved on its architrave. The small building has three niches: the middle one hosts a painting of Our Lady of the Rosary with the Child and the three Horns of Canzo in the background; the one on the right depicts Sain. Miro, dressed as a pilgrim, with a stick and a water bottle, again with the Ravella Valley on the background; in the one on the left hosts a painting of Saint Francis. From the chapel onwards the left edge of the path is protected for a hundred metres by a 1.20 metre high wooden railing, which stops leaving the edge unprotected for 40 yards until you reach the square of the Shrine of S. Miro al Monte. In the clearing in front of the precinct, at the base of the rock hosting the cave which Saint Miro used as a shelter (a statue of Our Lady has been placed at its entrance), in 2005 the Cumpagnia di Nost Association built a serpentinite fountain under a jet of water, which, according to local tradition, he had made flow out from the rock. This wellspring is considered sacred by the people of Canzo, and its water was used to cure diseases.

The Shrine’s square (approximately 20 X 15 metres), which is gravelled in its front section, is preceded by a low wall (30 cm) upon which you can sit, and opened in the middle to allow access to a paved pathway leading to the porch in front of the church, the construction of which began in 1643.

The left side of the square (when facing the Shrine) is limited by a low wall (approx. 30 cm) – upon which you can sit – surmounted by a 1.30 metre high iron railing; more or less in the middle there is another fountain.

Beside the church you can see a small two-storey building, which housed a number of monks probably connected to the nearby monastery of S. Francesco, until it was suppressed at the end of the eighteenth century. The monks cultivated medicinal plants on small mounds, which are still visible, made with dry stone walls on the opposite side of the Ravella stream (“Giardin di Fraà”, i.e. “The Garden of the Brothers”).

You are now ready to walk back to Gajum.