Unique in Europe, the Grand Canyon of the Verdon Gorges owes its diversity and depth to the considerable thickness of tithonic limestone dug by the river as well as by traditional processes of karst erosion (formation of underground streams, caves, sinkholes and collapses) and torrential erosion processes (shaping of potholes). These phenomena, well described by scientists, have taken on an exceptional magnitude in the Verdon Gorges.