The populated areas are mostly located on the plain and hillsides of Olot. A field of lava covers most of the plain (some 25 km²), and lava flows continue down the valley of the Fluvià to Sant Jaume de Llierca. Another important sector is in the tectonic valley of the River Ser, at the foot of the fault scarp of the Corb and Finestres ranges, with the volcanoes of Santa Margarida and Croscat. Lava flowed down the valley, past Sallent de Santa Pau to the Gibert mill. A third group of volcanoes lies in the Llémena river valley and the stream of Adri.