GLACIAL PHENOMENA Today´s glaciers are just a modest reminder of those that perodically covered the alpine chain and all of Europa from 1 million years ago up until about 10 thousand years ago. The Park contains many traces of these ancient glaciations: ice-polished and striated rock, erosion channels, shafts and potholes. Abrasive action on the bedrock by enormous masses of moving ice created the rounded and polished appearance of the rocks. The channels and potholes, with their varying shapes and sizes, were formed by the action of melting ice. During the warm seasons a portion of the glacier&´s surface melted. The streams thus produced sometimes fell into crevasses. These cascades carried with them sand, gravel and hard rock pebbles that fell with a whirling action that dug deeply into the softer bedrock.
The water and its detritus exerted an enormous force due to the height of its fall, which could sometimes be as much as hundreads of metres - the thickness of a valley glacier. Well-rounded pebbles can sometimes stil be seen at the bottom of potholes, and the area is dotted with erratic light-coloured granite blocks that were carried along by the glacier and abandoned at its point of withdrawal.
ROCK CARVINGS Numerous traces of man&´s presence over many centuries can be found here on polished rocks, the vertical walls of old quarries, isolated boulders and small caves. These rock carvings express man&´s need to communicate. Figurative drawings and dates appear side by side with geometric abstractions, signs, initials and symbols. Their meanings are often still unclear because of the difficulty in decoding the messages. A thorough study is under way to examine all the rock carvings.
POTSTONE Chiavenna "greenstone" varies in hardness due to the different combinations of minerals present. The softest type of stone, suitable for the production of pots by turring, is called potstone. This stone has been quarried continuously. There are also several archaeological finds from Roman times made from potstone: a vessel fragment, an urn and a funerary stone. The earliest evidence of a quarrying business at Piuro dates back to 1356 and such activities werw subsequently regulated. Workshops for turning the blocks were situated on the valley floor beside the river at Prosto and Chiavenna. Traces of this activity are preserved in place names, such as bottonera, from "botòn", pot-turning waste used for road paving.
GLACIAL GEOMORPHOLOGY Glacial erosion has sculpted the landscape of the park. Mountain terraces can be found at various levels all along the left bank of the river Mera. Standing out over the riverbed are rocky mounds, clusters of boulders, cliffs, gorges and erratic blocks of granite, with the valley separating the foothills from the lower mountain slopes. Potholes or giants&´ kettles (marmitte dei giganti), of polished, veined rock occur in the centre and on the slopes of these glacial valleys. Varying greatly both in size and shape, these potholes form an interconnecting system of shafts and basins. According to experts, this is the finest example of this particular phenomenon from the great Quaternary glaciation period in all of Europe. The Park contains wedges of mafic and ultramafic rock, commonly known as "greenstone of Chiavenna" (ophiolites). These are fragments from the ancient oceanic floor of the Tethys basin, some 150 million years old, comprising a great variety of rocks produced from the consolidation of basic and ultrabasic magmas. Metamorpgosis has been so intense that the primary mineral association has almost completely disappeared, the minerals now present are mainly serpentine, chlorite and talc. The area is also characterised by the presence of thrust formed out of huge blocks of "greenstone" containing faults and fractures. The series of landslidesd that caused this phenomenon occured some 15 thousand years ago with the withdrawal of the lateral support provided by the body of the glacier. A complex system of winding cracks within the thrust provides a constant stream of air at a steady temperature of between 6-10 degrees. These currents, known locally as "Sorèl", have been exploited by building "Crotti" cellars with three stone walls and one brick one with a simple room above.
LANDSCAPE AND VEGETATION The Marmitte die Giganti park is situated on the last slopes of a mountain range, which begins in the upper reaches of the Valchiavenna to the east and the Val Bregaglia to the South. The area includes the Natural Reserve of Regional Interest and a neighbouring area also classified as being of environmental interest. Old mule tracks and paths criss-cross thye park and lead to the ancient potstone quarries. The entire area provides breathtaking landscapes and majestic and fascinating example of geomorphology. This is one of anthropological activity dating back thousands of years, historic and prehistoric features of great interest and plentiful and varied plant life, with the most significant and rare species kept in the Paradiso botanical garden.
The woods are prevalently comprised of autochthonous tree species: Chestnut, Hornbeam , Ash, Mountain maple, Lime, Oak, Cherry-tree and Whitebeam. There are also many exotic species such as false acacia, Red oak and some Deodar ceder. The rupicolous vegetation is particularly interesting: Scot&´s pine, Juniper, Broom, carpets of heather, Red lily and Wild rose. Many specimens of Laurel, Arboreal heather, Hawthorn and Opuntia indicate the presence of a sub-Mediterranean microclimate.
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Informazioni ex art. 1, comma 125, della legge 4 agosto 2017 n. 124
Relativamente agli aiuti di Stato e aiuti de Minimis, si rimanda a quanto contenuto nel
“Registro nazionale degli aiuti di Stato” di cui all’articolo 52 L. 234/2012 (www.rna.gov.it).