The thermal springs, the “Bollente”, the “lago delle sorgenti” and “acqua Marcia”, is the same water that fell as rain and snow on the Apennines, at an average height of 800 metres, probably more than 1.500 or 2.000 years ago. During this extremely long period of time, the water slowly penetrated the ground, until halting at a considerable depth on a basement, a sedimentary platform of Mesozoic rocks (ophiolites, carbonates and evaporites) at around 2.500 – 3.000 metres in a primary tank, where in relationship to the so-called geothermal gradient, for which there is an increase in temperature of 1°C every 33 metres it descents, it acquires the unique boiling hot temperature that distinguishes it, that of the “Bollente” and in part the springs of the “lago - lake”.
The presence of faults, or rather of striking cracks in the earth’s crust have favoured especially in the case of the “Bollente” a rapid and uncontaminated re-climbing, therefore it maintains the same temperature that it acquires underground in the depths of the earth.
During its millenary journey, the water from the Apennines has crossed the saline relics of that enormous sea that during the Mesozoic era, or rather, between one hundred and two hundred millions of years ago, occupied the foundations of Northern Italy, and brought with it a significant richness in sodium, bromine and iodine. On the other hand, the chemical processes brought on by the water in presence of the carbon dioxide with chalky sediment deposits found at the bottom of the tank, explains the presence of sulphates and indirectly of sulphides.
Chemical composition of the: “BOLLENTE” SPRING (temperature around 74,5°C )
pH: 8,4 Fixed residue at 180°C: mg\l 2.200,0
Sodium Na+ mg\l 665,1
Potassium K+ mg\l 15,5
Magnesium Mg++ mg\l 0,1
Calcium Ca++ mg\l 127,8
Chlorine Cl- mg|l 1.095,0
Hydrogen Carbonate HCO3- mg\l 29,3
Sulphate SO4 -- mg\l 207,0
Bromine Br- mg\l 3,7
Iodine I- mg\l 0,5
Sulphur HS- mg\l 1,86