The salt marshes are where Guérande salt is produced. Sea water passes through a succession of ponds and is gradually evaporated. The salt contained in the water is concentrated until it crystallizes; it can then be harvested.
The sea water is carried by “étiers”, or channels, to the salt marshes. These long channels vary in length and are filled according to the tides and specific measurements.
The salt-worker’s know-how allows him to choose the ideal moment for filling a pond known as the “vasière” via a system of hatches. This first evaporation pond acts as a reserve to help cope with variations in sea level between two tides. It also has a second role as a separating pond in which the water from the sea deposits all the suspended impurities and silt that it contains.
Once this initial separation has taken place, the water from the “vasière” travels through the various ponds via a gradient system: these ponds are known as the “cobier”, “fards” and “adernes”.
|Pond||Salt concentration in g/l of water|
|Fares||60 à 100g/l|
The “adernes” provide a daily reserve that the salt-workers use to fill up the final set of ponds known as the “œillets”, where the salt and Fleur de Sel are harvested.
The “œillets” are small in size and have a platform on one side, known as the “ladure”, approximately 2m in diameter, where the salt-worker collects the daily salt harvest. The salt is then stored in piles (“trémets”) around the salt marshes for the season (June to September).
The salt harvest varies according to weather conditions. Depending on the year, it may be 50 to 70 kg of coarse salt per “œillet” per day and 3 to 5 kg of Fleur de Sel per “œillet” per day.