MINERALS AND ROCKS IN CENTOVALLI
AND TERRE DI PEDEMONTE



Since over half a century scientists all over the world know Centovalli for its deposits of important nickel, chromite, iron and asbestos mineralizations, especially on Mount Gridone’s northern slope. These mineralizations are tightly connected to the “Ivrea-Verbano” zone, one of the most important tectonic unit, which is characterized by the presence of rocks, that have their origin in the mantle, the layer directly beneath the Earth crust. The magnetic and gravimetric anomalies, which have been detected in this region and found in no other place of the Alps, are tightly connected with the underlying mantle. Another topic of particular interest is the presence of the so called “Insubric Line”, the main fault line of the entire range of the Alps. This is the result of the collision between the African and the Eurasian plates, which formed the Alps.

Minerals of special interest are also mentioned in the „Map of the Mineral Raw Materials of Switzerland“, which was published in the year 1994 by the Swiss Geotechnical Commission.

In this important document quite a few minerals, found in the valley, are mentioned, among these, next to nickel and chromite, also chrysotile (serpentine asbestos) of Mount Gridone, molybdenite of Intragna and feldspar, that is present in substantial quantities in Camedo and Bordei. Moreover in the flooding debris of the Melezza river the presence of gold, uranium and tungsten has been reported. This document mentions that in critical times through a political decision these mineral raw materials could be exploited.

Although the special geological structure of this region has right from the beginning inhibited the formation of minerals of bigger dimensions, with a few rare exceptions, the valley displays a certain richness of rock varieties.

The mineralogical research by Fabio Girlanda, the first of this kind in Centovalli, has ascertained the presence of about fifty minerals, a few quite common and others definitely more rare, which have been preserved since eons of time in the heart of our mountains.

Among the most notable discoveries almandine and exonite garnet, beryllium, diopside, chromo-diopside, magnetite, talcum, tremolite, olivine, corundum and zirconium are worth mentioning.

Some very seldom radio-active minerals, such as euxenite and polycrasium-yttrium, have their origins in the Pizzo Ruscada region. A few of these of particular scientific interest are presently being thoroughly examined.

Centovalli’s mineral and rock collection is on display at the Cà d'Amalia – Terra Vecchia foundation in Bordei (Palagnedra) (tel. 091-798 1218) as well as partially at the Regional Museum of Centovalli and Pedemonte at Intragna (Tel. 091-796 2577).

Among the beech forests, which cover the valley of Capolo, the remnants of the kiln are still visible, where in the past limestone was calcined. In these kilns lime was produced, which found several applications: from building and wall plastering of most private and public buildings in the municipalities of Palagnedra and Borgnone in the upper part of the valley, to home and stable disinfection, because of several epidemics, that did not spare this region either. Hence a product of the highest relevance, which was used until the end of the nineteenth century instead of today’s cement.

Unfortunately historical findings, which relate to this kiln, are rather scarce and fragmentary. Nevertheless, it is certain that it existed already around mid 1600. It is assumed that the lime used for building the famous Palazzo Tondù at Lionza (on the other side of the valley), which was built about 1670, came from this kiln.

The only relevant historical data can be found in the “Libro dei Terrieri di Camedo“ (Property Register of Camedo) and in the “Libro delle risoluzioni dell’antico Comune di Centovalli” (Book of Resolutions of the Old Municipalitiy of Centovalli).

The Swiss scientist I. Schneiderfranken in his research “Ricchezze del suolo ticinese” (Richness of Ticino’s Soil) of 1943 attached the “Inventario delle cave e fornaci di calce in Ticino” (Inventory of Ticino’s Quarries and Lime Kilns) of the year 1895, in which for the Centovalli it was written: “Lime quarry (but much sand) near the kiln of Capolo interrupted since 1886 and near the kiln of Bordei interrupted since 1875. Already explored in ancient times, were used all over again ”.

The kiln of the Capolo valley, restructured in 2002, belongs to the patricians of Palagnedra and Rasa. It has a round shape of 3.5 m in diameter and 3.30 m in height. It is a rather rudimentary construction, which consists of a hole in the slope and a dry wall made of stones found on the surrounding area.

It can be easily reached in about 30 minutes on a comfortable path, which starts at Pian del Barch (972 m over sea level): a beautiful way with an outstanding sight on most of Centovalli.

The Capolo valley splits open to the south of the village of Moneto to the foot of the impressive Gridone North Wall. It is a wonderful landscape, which is mentioned in the "riserva forestale di Palagnedra" (Forest Reserve of Palagnedra) and in the "lista cantonale delle zone di interesse naturalistico e paesaggistico" (Canton Register of Landscapes of naturalistic and scenic interest) and presents interesting geological and botanical aspects. Here you can admire the asclepias-gentian or the extremely rare serpentine-fern (asplenium cuneifolium). The latter can only be found in three other places in Switzerland.

THE SOAPSTONE IN CENTOVALLI

Thanks to its low hardness and particular thermal characteristics soapstone (“güia” in the local dialect), has been used since over two-thousands years for the production of a multitude of objects, both for household use as well as for religious matters.

The Centovalli and the Terre di Pedemonte, however, cannot boast about a hundred years old soapstone delivery and processing tradition as other valleys of Locarno do. The main reason for it is perhaps fact that it is mainly a rather hard kind and difficult to work with, although in the whole region there are about ten deposits. Just in three or four places traces of delivery in the past centuries are evident. A large part of the soapstone objects, which you can find in all the villages of the valley, has probably been produced with material that came from the many quarries of nearby Vigezzo valley. It is also possible that, for instance, the spray basin, which are still being preserved in many homes, come from other Ticino’s regions and have been bought at the weekly street market of Locarno. Still, something must have been produced out of soapstone of the area.

The most interesting deposit is the one of Riale di Borgnone, right below the village that bears the same name. On an area of about 30 m2, delivery traces are clearly visible, among others those of plates, used perhaps for constructing a seldom kiln in the upper valley.

Rather well visible delivery traces, but covered by a thick vegetation, you can also notice in the quarry above Verdasio. Processed rock chunks and niches are evident. From this material plates for kiln construction could have been extracted.

The most frequent objects one can find, are mortars, in which nuts and chestnuts were ground, and containers in numerous, rather large shapes and weights, which were used for the conservation of pickled meat, butter and salt. On the church parvis of Verdasio it is possible to admire a monolithic fountain, while in the courtyard of the Tosetti house are other noteworthy objects, such as a press wheel and a mortar that bears the engraving “Tosetto”, the old name of this family. A little further, in another home, there is a particularly beautiful, conical mortar, which has been produced from a soap stone of the area.

Objects from the ancient roman time have been found during excavations in the Terre di Pedemonte. It has been reported that in Tegna a Neolithic axe has been recovered, while in Cavigliano in the year 1944 six graves from the first and second century A.D. were found, that contained glasses, flat cooking pots and ornaments.

THE PEAT MARSH OF THE HILL ABOVE COMINO

Along the mountain ridge of Pizzo Ruscada, on the left side of the valley, stands the hill of Comino, a wonderful sunny hill with an altitude of 1000 to 1200 m over sea level. From Verdasio, one of the most typical villages of Centovalli, you can comfortably reach this hill, which by the way belongs to the widest of the Canton of Ticino, with the cable car, that was built just a few years ago, or in less than an hour on a comfortable path, which displays wide bends. Below the hill, in an enchanting place of outstanding fascination and beauty, the little church of the Madonna della Segna, built in the year 1647, is standing, since centuries venerated by the local people.

Behind this place of prayer, on the watershed to the Onsernone valley, is a wide basin surrounded by forests, where one of the most important naturalistic jewels of Centovalli is located, the peat marsh of Pian Segna, which is mentioned in the list of the peat marshes and swamps of national importance.

This peat marsh has an extension of about an hectare and is mainly characterized by typical habitat species. They consist of little bogs (caricion fuscae) and peat marsh heaps (Sphagnum sp.), a particular musk species, that absorbs much water (up to 40 times its initial weight). On a long process peat is formed out of its decomposition. Peat is being used for plant and flower growing and in the past was used especially as a fossil fuel, however of low heat yield. It was therefore called the "coal of the poor people".

Furthermore on this peat marsh also grow the sheathed spandrel (eriophorum vaginatum) and the round leafed sun rope (drosera rotundifolia), a meat eating plant, which feeds on small insects, such as ants and flies, in order to compensate the missing of nitrogenous composting in the soil. Other plants living in this special habitat are the moorland witch (molinia cerulea), tricophorum caespitosum, juncus effusus, carex flava, carex panicea, carex fusca, licopodium inondatum, empetrum nigrum, while around the peat marsh grow the mountain arnica, the astrantia, the spotted orchid, the gold rod, the heath herb, the blueberry and many other plants.

In this peat marsh lives a red frog. Two species of ringed snakes and three of dragonflies, among which the rare somatochlora arctica, have also been observed. Furthermore Bär, a scientist, spotted in 1915 the heodes virgaureae, a butterfly with copper colored wings.

The peat marshes are rare habitats of outstanding beauty. From a naturalistic standpoint, they are among the most precious habitats of Switzerland and represent vital spaces of substantial ecological value for protected plants and animals.

Unfortunately senseless works, which man in the past years has performed, have seriously damaged the peat marsh of the hill above Comino, with all the negative changes in the water balance.

Fabio Girlanda - CH 6653 Verscio - +41 (0)91/796.17.80