While strolling along the Corniche Kennedy, you’ll spot a small, unassuming building near number 174. You might think it’s just an ordinary house, but it actually houses a special monument: the Marseille tide gauge. A true benchmark for measuring all elevations in France, this scientific and historical installation sparks a great deal of curiosity. Marseille Secrète tells you more about this “point zero” of French elevation.
A device unique in the world
Let’s start with a quick definition exercise. After all, what is a tide gauge? The term refers to two things:the device that measures sea level and the building that houses it. The Marseille tide gauge was installed in 1885 to determine the reference elevation for mainland France. While researchers today use a digital tide gauge, the old mechanical device is still in operation, making it the only one of its kind in the world.
The Marseille tide gauge, the zero-elevation reference point in France (and Switzerland!)
It is therefore from this historic tide gauge that all elevations in France are calculated. As the true “zero point” for elevation, it is thanks to this gauge that we know Mont Blanc stands at 4,810 meters, the Eiffel Tower at 324 meters, and the Bonne Mère at 162 meters. Furthermore, since Switzerland has no coastline, it uses the Marseille tide gauge as its reference point.
In addition to measuring elevation, the tide gauge also serves asa scientific observatory. It plays a key role in monitoring one of the many effects of climate change: the rise in average sea level.
The association “Les Amis du marégraphe de Marseille”
Marseille was chosen to house the tide gauge primarily because of its low tidal range. When France was required to designate a site at the request of European authorities in 1864, this was the criterion it selected. Listed as a historic monument since 2002, the tide gauge is very rarely open to the public. However, the association “Les Amis du marégraphe de Marseille” offers virtual tours for those who are curious.
