The shingle comes from the slow and inexorable breaking up
of the Pays de Caux cliffs. Having fallen into the water,
the pieces of flint are rolled, eroded by the waves and gradually
take their characteristic rounded shape.
Originally, before the gradual depositing of the salt
marsh bar, the shingle would end its journey in the
complex of estuaries of the Somme, the Maye and the
Authie. Vast banks were then created, which form the
basis of today's le Crotoy quarries in Rue.
North of Ault, the breaking up of the cliffs has gradually
created a shingle bar, which protects the Cayeux-sur-Mer
salt marshes from the sea's intrusions. This was how
the Hâble d’Ault became isolated from the
sea.
A mining resource
The quantities available and their
unequalled content of silica (over 95 %) make the shingle
an outstanding mineral resource. It is used as a by-product,
after calcination and grinding, for making roads, buildings,
and also sanitary facilities, paints, cosmetics, and
false teeth.
The shingle collected straight from
the foreshore is the most sought-after because it is
of a much higher quality than shingle from inland quarries.
Of great ecological importance
The shingle areas provide new kinds of habitat that are rare
in continental Europe. They are home to plants which do not
need soil, like the Sea kale Crambe maritima, a nationally
protected species because of its great rarity. A succession
of similar plants, mostly low-growing but with brightly-coloured
flowers, embellishes the bluish hue of the shingle bar.
With regard to birds, uncommon species like plovers find
this flat and sparsely-planted area a suitable breeding place.
The Hâble d'Ault, protected by the shingle bar, is a
vast area lacking in tall vegetation, and is home to exceptional
flora and fauna. A circular walk enables you to explore the
shingle bar and the Hâble d'Ault. For more information,
please refer to the
espaces nature Somme circular walks, or, for guided tours,
to the schedule of guided nature outings.
