The "Balze" of the Valdarno
Following the ancient Cassia Vetus road, today Setteponti, through small villages of Piantravigne, Persignano, Poggitazzi, Penna and Loro Ciuffenna, you will come across fascinating geological formations called "Balze" (cliffs) that somewhere give this land the unusual appearance of small canyons.
The origin of these formations is prehistoric: in the Pliocene, about 5 million years ago, all the Valdarno was covered by a vast lake, whose shores were the current Pratomagno and the Chianti hills. In the Pleistocene, about 100,000 years ago, due to movements of the earth's crust, the water flowed in the direction of Florence by the Arno, which together with its tributaries began to erode the sediments deposited on the lake bottom, creating gentle undulations in the central areas the valley, and near to the Pratomagno it formed these harsh clay formations, also modeled from the elements over the millennia.
Even Leonardo Da Vinci was impressed from them, so much that he decided to study the geology of the area and paint them in the background of the "Mona Lisa"! Today, the Balze are among the protected areas of Tuscany. Their erosion continues, and it is estimated that in a few thousand years they will be completely gone.