The Triassic gypsum include a stretch of about 10 km of Val Secchia where the river has deeply carved the current geological formation forming the whites and steep sides of the valley. Due to the high solubility of gypsum karst phenomena occur in these rocks and have given rise to some outcrops. These rocks are evaporite of more than 200 million years old, deposited in the waters of the ancient sea of Tethys which, evaporating within large lagoons, deposited gypsum and salt.
Salt, more soluble than gypsum, is today only in depth and is actively dissolved by water seeping. This is why the References of Poiano are salted and why in this area karst phenomena occur, giving rise to small sinkholes and caves. The landscape of gypsum is harsh, varied and full of contrasts: cliffs, semi-arid grasslands, juniper formations, scrublands of flood and helichrysum along the sunny slopes, shrubs, dense woods of Ostrya spp., forest formations along the cool northern slopes, chestnut trees and lush vegetation riparian.
The chalky areas are rich in habitats, plant and animal species, also of European importance, due to the environmental mosaic determined by geomorphology and karst. The areas of Triassic gypsum, as well as the Pietra di Bismantova, are sites of Community Importance (SCI IT 434 030 009) and are part of the Appennino tosco – emiliano National Park.