Erosion pyramids

Shortly before reaching Zone, in the hamlet of Cislano, the majestic scene of the Erosion Pyramids opens up, commonly called “Stone Fairies,” but scientifically identified as “erosion pyramids.” This very rare natural phenomenon, with few examples worldwide, is caused by the action of water on steep moraine terrain; the large boulders resting on the tops of the pyramids act as protective “hats” for the underlying soil, thereby reducing the effects of water. They constitute an important record of the geological evolution of the Alpine glacial and post-glacial era.

The vast moraine deposit from which they originate was left about 150,000 years ago by a lateral tongue, which penetrated the Bagnadore valley, of the imposing glacier coming from the Camonica Valley that, during the third Riss glaciation, filled the basin now occupied by Lake Iseo.

Moraine soil is a mixture of earth and small pebbles of different sizes and various origins, cemented and hardened just enough to have some consistency, but also easily eroded by rainwater washout. The erosive action of rain on the moraine deposit gradually isolates large rock boulders (up to 6 meters in diameter). These boulders exert a protective umbrella effect on the underlying material, shaping a column of earth, the pyramid, which can reach up to 30 meters in height, and is also protected by a thin film made of insoluble clay transported by water along its sides. When the boulder on the top falls, the pyramid quickly disintegrates until it finds another “hat” at a lower level, a very delicate magic due to truly particular environmental situations and physical combinations.

Regional Reserve