Since the bay is submerged, that made 8000 years, the sediments accumulate naturally around the Mount-Saint-Michel.

These fine sands, them “pitch”, brought by the flood all are not taken again by the ebb. Nearly 3% of these sediments accumulates in the zones out of attack of the rivers, raising by place the strikes of more than one meter time of only one summer.

Spaces which the tide does not bathe any more that at the time of the sharp water are colonized by the herbu, increasing by 25 to 30 hectares each year, which thus gives to bay a character more pastoral than maritime.

To free from sand bay, i.e. to remove the sediments which settle there, are out of our range. But it is possible to restore and maintain to the Mount-Saint-Michel a sand space naturally maintained by the rivers, criches and fibres, and to stop the invasion of the herbus which threaten to encircle the rock.

For that purpose, certain works built by the man will be modified so that the currents of erosion make their maintenance work.

Carte : Mission du Mont Saint-Michel/Anne Chappuis