IN THE PROVINCE OF AREZZO rise the Balze del Valdarno, mountains that were formed after the drying up of a lake during the Pliocene era and, subsequently, thanks to the action of exogenous forces such as water and wind.

One striking feature of the Balze is its three distinct layers. The top of these mountains is brown because many pebbles and fine sand protect them from erosion caused by rainwater. The middle section is yellow because of clay and silt deposits, which are easy to erode by atmospheric agents. At the base of the mountains, there is a layer of material called scree, which is made of rock fragments and other debris that broke off from the upper layers and accumulated at the base.