The mountain group of Valmontagna and Frasassi is characterised by a folding geological motif, with a wide limestone anticlinal corresponding to the orographic relief, and narrow synclinal which correspond to valleys and plans (Pianello di Genga's area – Saint Vittore Terme's Area). Water circulation constituted by river Sentino entered these geological structures, after orogenesis events, helped by faults and “diaclasi”(wide cracks in rocks).
These rivers, obstructed by the Mountains of Frasassi, formed, at the beginning of Pleistocene, a wide lake next to Pianello di Scheggia, and getting deep through the breaks of calcareous rocks they reached the ”Evaporitici Riabliani” deposits below, made of rock-salt , chalk and bituminous levels(AGIP Burano Well). Through the millenniums the stagnant water in Pianello-Genga's area, operating deep and subjected to great Hydrostatic pushes, caused the solution of “Evaporiti Riabliani ”, melting rock-salts and chalk, splitting the latter in calcium bicarbonate and sulphureous acid (sulphureous water). Through this mechanism, the water ,enriched in depth by mineral salts , blocked by impermeable grounds, obliged by communicating vessels law, ascended along the fault plans with springs and streams in Saint .Vittore Terme, where topographic surface is lower than the feeding basin.