The coast of Picardy extends over 65 kilometers (40 miles).
Covering 3000 hectares (7,400 acres), the Somme Bay estuary
stretches from Le Hourdel point in the South to
Saint-Quentin-en-Tourmont point in the North. The Bay
has been silting up gradually, reducing the activity of the
harbours at Saint Valery sur Somme and Le Crotoy.
Over time, the construction of dykes (known as « renclôtures »)
and of a trestle bridge to carry the railway across the Bay in the
19th century, have both contributed to this process.
North of the Somme Bay, the sand dunes of Marquenterre were created through the same process of the coastline moving outwards. The first dykes were built from the 12th century by the monks of the neighbouring abbeys (Saint-Riquier, Valloires). The sand would build up against these embankments and gradually form dunes, which extend inland, linking this part of the coast to the Opal coast further North. Naturally, the beaches are extensive sandy areas.
Within the Bay itself, the two main environments are “slikke” and “schorre”, also known as “mollières”. The slikke is an area that is covered by the sea twice a day at high tide, meaning mudflats which are particularly damp, whereas the schorre is an area that is covered by the sea only during king tides, and where sheep (known as “pré-salés”) can graze most of the time. Here and there, pools of water remain, used for shooting wildfowl.
Le Hourdel point marks the southernmost limit of the Somme Bay. Its main feature is a flintstone embankment which heralds the coastal scenery further South.
The low fields of Cayeux recall the Dutch polders and the Belgian blotteland, which is also encountered on the French coast of Flannders between Bray-Dunes and Calais. The agricultural land, located below sea level, has been reclaimed over the sea by filling the gaps where the water used to flow in. The water is drained off via man-made canals (known as “nocs”).
South of the Picardy plain, the coastline features chalk cliffs, from Ault to Mers-les-Bains, which announce the cliffs of Normandy. A bank of shingle overlooks the beaches. The sand, always damp, is visible only at low tide. The cliff, some 40 meters high at Ault, drops gradually down to sea level from Onival.
This scenic variety contributes to the presence of many animal and plant species.
The habitat is very favourable for both sedentary and migrating birds, which can be observed in the Somme Bay natural reserve or in the Marquenterre ornithological sanctuary, where large numbers of water fowl (mallard duck, teal, widgeon, gadwall...) as well as shorebirds (snipe, curlew, oystercatchers, lapwing…) are to be found.
The Somme Bay is also home to the largest seal colony in France (60% of the total population). The species had been severely depleted in the late 19th century (intensive hunting), but re-appeared naturally during the 1980s...
Two types of seals are currently found in the Somme Bay:
- The grey seal
- The common seal
At low tide, the seals rest out of the water, using the sand banks to rebuild their energy (all the year round), to give birth and feed the offspring (from June to September)… The number of seals therefore varies depending on the season and the tide schedule.
The largest number of seals observed in the Somme Bay was 557 common seals (on 27/08/2016) and 185 grey seals (on 05/06/2016). These were animals that were resting.