LES MARAIS DOUX DE SAINT HILAIRE DE RIEZ

The gentle marshes of Saint Hilaire de Riez cover 2,500 hectares.

The soft marshes were formed by the deposition of alluvial deposits (debris of sand, mud and clay transported by watercourses), which, fixed in the low-lying areas, filled in the valleys, creating banks and mudflats on either side of the Sion plateau. These serve to anchor the dunes, which, pushed by the wind and currents, accumulate in front of the shore, isolating the low marshy areas. With the land thus isolated from the sea, the marshes gradually became desalinated, creating the soft marshes. This area is of considerable interest to everyone, regulating watercourses and preventing them from flowing too quickly and causing flooding downstream. True ecological purifiers, they facilitate the decantation and filtration of nitrates and pesticides.
The fauna is rich and distinctive, with wading ducks, geese, lapwings, herons, white egrets, marsh harriers and eels. The flora consists mainly of poplars, alders and willows.