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by Christian Encarnacion

The structure of a saline.

If you do a quick search of Guérande, France on Google, you will see what looks like misshaped puzzle pieces near a beautiful blue sea. What many people don’t realize is that this landscape is the result of an artisan practice dating back to the Middle Ages! Known as marais salants, or salt marshes, Guérande is molded by these man–made artifacts. Even to this day you can purchase French bay salt at a number of online websites, and it is a prominent ingredient used amongst gourmet chefs. With regard to our 17th century Ship Biscuit and Salted Beef (SBSB) study that we’ve been conducting these past few months, this salt is the same salt that was used by 17th century sailors for their own food preservation! But wait, how exactly is all this salt harvested?

Known as paludiers, salt–makers set up their homes near the salt marshes to facilitate this centuries–old practice. Depending on the paludier’s preferences, each saline has its own variation in regards to size and the number of channels and reservoirs. In general, each saline is constructed so that seawater flows along the same pathway. Seawater is collected through small creeks (etiers) that go through artificial channels (bondres) where they get stored in reservoirs (vasieres). When high tide occurs, the water is collected through a small gate (cui) underneath a raised bank (talus). At this point, the water goes through a series of basins with gradual decreases in elevation. At each basin, water is heated and evaporated and silt and algae are decanted. Once it passes the tour d’ eau, the water slowly circulates downward into smaller basins (refer to the cross section). By the time it reaches the oeillets, the salinity of the water is approximately 27%. The oillets are further divided into ponts that are made of compacted hard silt. From here, a paludier can extract the collected salt, where it’s left overnight on a ladure for drainage. The harvesting of the salt (the prise) is considered the most taxing and requires a lot of endurance and dexterity.

A paludier transfers salt on a wheelbarrow.

This entire process usually takes several weeks to two months. Maintenance of these salt marshes is year round; paludiers have to constantly monitor banks and cut off excess vegetation that might interfere with seawater flow.

The fact that this method of salt harvesting has been kept from generation to generation is extraordinary. With our SBSB study, we were able to maintain this ingredient of a 17th century recipe intact. Currently, we have discovered some unique microbes found in the French bay salt that was used in our simulated preservations. Knowing the way that this salt has been harvested, it could be possible that these microbes may have come from the salty marshes of Guérande!



Thompson IB. The role of artisan technology and indigenous knowledge transfer in the survival of a classic cultural landscape: The marais salants of Guérande, Loire-Atlantique, France. Journal of Historical Geography. 1999;25(2):216-234.

Special thanks goes out to Andrew Fielding of Ecosal-UK for his help with salt research within our project.