
The landscape of the grassland and the Millefonts lakes is the direct result of the geographical model put in place by the last glacial period. The glaciers created deep hollows in places and in other created natural dams called. The two phenomena naturally created mountain lakes. However, sediment and organic plant matter tend to fill the lakes in, leaving just a wet and marshy area: the peat bog.
These environments are very rich in plant life but also highly fragile. An excellent example can be see downstream of the small Millefonts lake.