- north of the Somme Bay: the dunes of Le Marquenterre form a unit of approximately 240 ha, of which 45 ha are pine forest.

- south of the Somme Bay: the Brighton dunes cover 50 ha.

The dunes, a rich natural environment

382 plant species have been recorded here, of which four are protected on a national level (Fen orchid, Seaside pansy, Round-leaved wintergreen, Lyme-grass). Twelve other species are protected on a regional level.

The dunes are home to 60 species of nesting birds. The fresh water ponds in the depressions are an ideal environment for the Great crested newt. You can also find other batrachians there, like the Natterjack toad and the European treefrog.

Shifting and fragile environments

The wind puts the sand in motion and reshapes the landscape endlessly, and the buffeting of the waves is constantly eroding the dunes. The ever-changing nature of the terrain is amplified by the activity of walkers, which can have catastrophic results when it becomes too intense. Finally, to this dynamic must be added the growth of vegetation which tends to fix the sand and create dense shrubby areas once the sand is stabilised.

The fixing of the dunes, in particular with the planting of beachgrass, dates from the beginning of the XVIIth century, and was intended to prevent the movement of the sand towards inhabited areas.

Circular walks give you the opportunity to explore the natural heritage of this dune environment. For more information, please refer to the espaces nature Somme circular walks, or, for guided tours, to the schedule of guided nature outings.