This passage, which provides access to the Chartreuse range from Chambéry, owes its distinctive physiognomy to the sheer face of Mount Granier which dominates it. In 1248, torrential rainfall led to the mountain's collapse, numerous villages were buried and 5,000 lives lost. The mass of stone and rock at the foot of the mountain create a chaos called the "abymes de Myans", today overrun by vegetation, but recognizable by the small mounds dotted with little lakes.