Val del Grisol, originated from the confluence of a network of small valleys furrowing the eastern slopes of Schiara-Talvena group (Val dei Ross, Val Costa dei Nass, Val Grave di S.Marco) is an isolated and solitary valley dug into Jurassic marine sedimentary rocks (flinty dolomite rocks, marls, and limestones).
Steep slopes and high rocky drops characterize the outcropping areas of the compact formations, while gentler slopes can be found only on the degradable marly formations.
Among the most interesting valleys of the Park, Val del Grisol differs from the others for the distinctive features of the wet, cool, and shadowy ravine environments and for the quality of its Silver Fir and Beech Tree woodlands.
The Silver Fir often dominates between the 600 and the 1,100 meters of altitude, where it is particularly luxuriant and associated with the noble broadleaf trees (Common Ash, Mountain Maple, Norway Maple, Wych Elm, Bigleaf Linden). Among the most interesting floristic species, the Euonymus latifolius and Lunaria rediviva are worth a mention. This forest has extraordinary features, unique in Europe.
Moreover, the Silver Fir woodland of Val del Grisol is one of the most interesting wildlife habitats of the Park (Northern Goshawk, Hazel Grouse, Black Grouse, Tengmalm's Owl, Black Woodpecker, Pine Marten, Deer, and Roe Deer).