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A bit of geology
The reserve's territory is made up of Ceppo, a sedimentary rock composed of pebbles and sandstone cement, which gives rise to 14 springs.
The Reserve's geological history is important for understanding its natural features, particularly the springs. The Reserve's geological highlight is the "Ceppo Formation." From a mineralogical perspective, it is a conglomerate, a rock composed of pebbles of varying sizes, bonded together by a sort of natural cement (which in this case is quite rich in limestone, or calcium carbonate), which, however, leaves numerous spaces between each pebble. These spaces allow the Ceppo to function like a sponge and absorb water, the same water that forms the so-called "aquifer," responsible for the presence of 14 springs within the Reserve.
The Ceppo: What It Is and Where It Comes From
To better understand, it's best to start from the last million years, in what is called the Quaternary Era. At that time, the Earth was subjected to numerous periodic climate fluctuations, which led to severe climate changes and the subsequent onset of ice ages. Coinciding with the Earth's cooling, large masses of ice (glaciers), currently confined to the Alps above 3,000 meters, descended into the Po Valley, sometimes reaching the outskirts of Milan and even affecting the area where the Reserve is currently located. These cold eras were followed by brief warm periods, called "interglacials," during which the ice melted, giving rise to enormous rivers that, as they flowed toward the sea, carried and subsequently deposited on the plains a vast quantity of pebbles and sands of varying composition. The stones, originally sharp-edged, were shaped by the water until they developed the typical rounded shape we see on the beds of modern rivers. These enormous pebble deposits, particularly the older ones dating back to the earliest interglacials, were buried by other deposits and were thus subjected to enormous pressure and the circulation of liquids rich in mineral salts such as calcium carbonate. Over the millennia, these deposits cemented together to form a compact rock, called a "conglomerate," consisting of numerous pebbles bonded together. These deposits are now known as the "Ceppo Formation" and cover much of central-northern Lombardy. The entire Reserve, represented by an ancient valley, has sides made of the Ceppo conglomerate, which is literally cut in half by the valley furrow, allowing the water contained within the conglomerate to emerge, forming numerous springs. The Ceppo outcrops constitute an important microenvironment for the flora, represented by small damp walls, on which numerous species typical of damp walls and dripping cliffs develop.
The Fountain
Evocative and magical environments, fountains have always attracted human attention since the dawn of civilization. Ancient and magical water-related rituals have often taken place around them, including those of the ancient Celtic peoples who once populated the area. Modern man has partially dispelled the mystery surrounding these environments, clarifying the mechanisms that cause the water to surface. Nonetheless, these ecosystems retain great charm, alongside their historical, landscape, and naturalistic values. In the Fontana del Guercio Reserve, there are as many as 14 fountains, some of which feature ancient walls made of large, unbound blocks. The presence of these springs is due to the Ceppo Formation, which functions like a sponge, retaining water from the aquifer and releasing it when the rock is cut in two by the valley: the springs gush out at the base of the valley incision.
How a fountain is made
A fountain consists of a section near the water outlet from the ground or rock, called the "head of the fountain" or "spring cup," which maintains a constant temperature year-round. From the head, a stream, called the "shaft of the fountain," branches off, where the temperature is typically found in a stream of similar size, and therefore varies throughout the year. At the head of the fountain, the points where the water emerges are visible, called "springs" or "springs," identifiable by the sand disturbed by the water emerging from the bottom. From a naturalistic perspective, the most interesting area of ​​the fountain is the head, due to its constant temperature, which in the case of our fountains is around 12 degrees Celsius: this environment is home to animal and plant organisms unique to water at a constant temperature. Spring fountains are partly artificial ecosystems, as the spring bowl is man-made. Over the years, plant debris, aquatic plants, and sand completely clog the head, which loses its naturalistic value. In the past, every 2-5 years, in winter, the spring fountains were cleaned of mud (known as "head purging") and the bowl restored. Nowadays, following the abandonment of agriculture, head cleaning has become one of the duties of the Reserve's managers.
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