A continuation of the Normandy cliffs, and reaching a height of almost 80 metres, the Picardy cliffs stretch for over 6 km between Mers and Ault.

The living cliff is not stable. Year after year, the cliffs continue to be eroded, leading to the destruction of whole sections, which constantly renews the landscape. At the heart of the six kilometres of cliffs nestles the Cise Wood, a small grouping of trees where the different houses built at the beginning of the century give it a picturesque aspect. Many species of plants brighten up the tree cover (daffodils, wood anemones).

The Picardy cliffs offer nesting sites for different species of birds, which are monitored on an almost annual basis. Amongst them, the Herring gull is the main resident. You can also find there more unexpected species: House martin, Jackdaw, Fulmar.

Les falaises picardes offrent des sites de nidification pour différentes espèces qui font l'objet d'un suivi pratiquement annuel. Parmi elles, le goéland argenté est le principal locataire. On y retrouve aussi des espèces plus inattendues : hirondelle des fenêtres, choucas des tours, fulmar boréal...

From Onival onwards, the cliff is no longer in contact with the sea because of the ancient layer of shingle. The shingle bar, which extends as far as Le Hourdel, protects the salt marshes at Cayeux-sur-Mer. It offers remarkable protection against cliff erosion. Here this is called the dead cliff, in contrast to the living cliff, which continues to be subjected to attack from the sea, sea spray and erosion.

A circular walk enables you to explore the natural heritage. For more information, please refer to the espaces nature Somme circular walks. There are also guided tours to this site: please refer to the schedule of guided nature outings.