Characteristic alpine environment, presenting forests and grasslands, heaps of stones and rocky walls, lakes and wetlands. The reserve, which is included in the big valley of the stream Pacoulla, is characterized by the presence of basins in the rock, which are of glacial morphology. They are disposed on different levels, now housing small lakes and peatbogs. The rocks which shape the big valley belong to the group of eclogitic mica-schists of the Sesia-Lanzo area.