The plains of Colfiorito, Cesi, Popola, Ricciano, Arvello, Annifo, Colle Croce and Palude di Colfiorito, are the seven plateaus called “Plestini”.
The plateaus form the bottom of ancient lakes, which have undergone the typical evolution of karst substrates, with the formation of sinkholes that have led to their drying up.
During the rainy period (from autumn to early spring) there is generally an accumulation of water, which is then slowly disposed of through one or more sinkholes. In few cases, the water remains in the center of the sinkholes. This exception is represented by the Colfiorito swamp: in fact, it is the only area where water still resists during the whole year, and is therefore one of the most interesting wetlands in the entire region.
