In addition to supplying its water to the lake of Longemer, the Vologne crosses a forest. These woods are home to an unusual stack of granite stones. Standing amidst conifer plantations, it is shaped like a rectangle several meters thick. It stretches over 1,300 ft (400 m) long and 131 ft (40 m) wide. One hypothesis is that a glacier dropped the rocks there some 50,000 years ago. This geological curiosity constitutes an ideal biotope for wood mice and wall lizards.