These unique blue pebbles that protect the bay of sum

Cayeux, in Picard, means “Caillou”. But on the beaches of Cayeux-sur-Mer, seaside resort of the Baie de Somme, we prefer “pebbles”. They are millions, rolled by the centuries, torn off by the swell from the cliffs of chalk and normandy flint, shaped by the wide currents. During these hundreds of kilometers of drift, the rocks are struck and collide in a patient geological work.

Brewed as in a “large washing machine” say the Cayolais. The estuary of the Somme being the first natural dam, the stones are deposited here and form the local treasure: blue pebbles, of an almost perfect roundness, composed of pure 99 %silica. A unique deposit in Europe; Some even say unique in the world.

Pebbles transformed into roads, into technical concrete

Since 1928, the Silmer factory (Silice de la Mer) has exploited this material. She harvests, sorts, washes and transforms the pebbles for the needs of the construction industry: a little ceramic, but especially roads, paintings and technical concrete. Every morning for almost two decades, Ludovic Manouvrier, 47, goes up in his loader. In front of him, the sea, the pebbles and the ballet of the birds take place. “With the view, alone facing the sea, the job is nice,” he said, smiling. In summer, taking the precious pebbles is the dream. In winter, a little less, with greyness and rain. But when the waves are unleashed, work becomes stimulating.

“The storms bring us even more pebbles. Sometimes, from his cabin, Ludovic sees seals, the local attraction – the bay of the Somme houses the largest colony of Veaux -Marins in France. Amused, he watches them bounce towards the rising tide. He also observes spatulas, egrets, sea pies, gravels and other birds. Until 2022, Ludovic did not work alone on the cord of pebbles. Colleagues sorters on foot surrounded it and formed small tasks on the horizon. Curved and armed with a wicker basket, they were called the coastlines. When they filled their windfall, they put a pebble aside. After twenty-five stones, they knew they had picked up a ton. A hard but overwhelmed job. “We are no longer in Zola,” says Brigitte Pagès, the director of Silmer.

Local industry flagship

From now on, the harvest is provided by Ludovic, its Finnish loader and a screech of 400,000 euros. The machine operates the sorting in three outputs: the small pebbles are redesposed on the beach, the means and the large are kept, the all-year redistributed on the foreshore. Then, in the nearby factory, the second life of the roller begins. Washing, manual sorting, calcination at 1,600 ° C, grinding: by a series of precise gestures, an industrial product is created. Cristobalite silica which gives exceptions, hard, white, opaque and reflecting UV and heat. “The Germans love our products for their roads. When it is 35 ° C outside, the road temperature rises to 60 ° C, our aggregates lower it by ten degrees, ”explains Brigitte Pagès.

In this factory of 29 employees, two men are responsible for a crucial operation: calcination. Christophe Briseville, 44, is the head of ovens; Fabrice Rimbault, 42, his second. Two children from the Somme Bay. Christophe comes from Hourdel, a hamlet located at the northern tip, where the pebbles end their big trip. After twenty-two years at Silmer, he spots good calcination with the eye and ear. “If it cracks, it’s not good. The pebble must sing, ”says the expert. Son of a fisherman, his mother worked in a cans. Here, the sea and the pebbles form a whole.

“We do lace, not mass production,” insists Brigitte Pagès. Entrance to Silmer in 1994, after a summer in the quality laboratory, she never left the company, which she has been running for three years. “The sea is our partner, our constraint and our pride,” she recalls. The company takes on a 900 m long coastal strip, which moves according to state authorizations. And everything she takes, she “restores” it.

Rampart against erosion

The word is released: restitution. It is the heart of the local model. At the rate of 55,000 t per year, Silmer returns to the sea what it takes to him. For each tonne taken, a ton is restored to the sea. Not just how: reinjected in the fragile areas of the coast, with pebbles at the right size, placed in the right place, under control of state services. Silmer finances the operation entirely (1.2 million euros per year). To guarantee the volumes, the company buys pebbles from quoins from northern bay. The stone is not so pure there, but the sea does its work of ennobling and in a few years, the silica rates reach 99 %. The sleight of hand allows the dike to be maintained, made of a cord of pebbles of ten meters on the whole coast, the first natural bulwark against erosion. Without this virtuous loop, the sea would advance. And when she decides to regain her rights, nothing stops her.

Viviane. The Cayolais still talk about this storm that struck the Picardy coast. Between February 25 and 27, 1990: winds at 140 km/h, Mer force 10, coefficient tide 96. The sea rises by one meter, floods the cellars, ravages shops and destroys 3,000 ha of cultures. François Mitterrand goes there with three ministers. Reconstruction costs the equivalent of 11 million euros. Viviane serves as an electrochoc. From 1997 to 2001, 80 protection ears were placed on the beaches around the city to protect the pebble cord – 24 were added in front of Cayeux in 2015. Behind these damage, we find the hand of man. Jets, port entries and nuclear power plants (in this case, that of Penly, in Seine-Maritime) are all dams for the carpet treading stones. These works hinder the natural infusion of the pebble cord. When less pebbles run up to Cayeux, the sea takes them easier.

Fragile resource

Thierry Bizet is deputy director of the Baie de Somme joint union – Grand Littoral Picard, a public community which brings together eighteen municipalities. He manages regional planning, observes, measures and acts. This geology enthusiast tells the roller’s trip from the Cape d’Antifer, Normandy, to Cayeux as no one. “Our coast is like a patient in the hospital, the infusion is the pebbles,” he explains. Between 1974 and 2011, before the construction of the 24 additional ears in front of Cayeux, the beach south of boulevard Maritime had retreated thirty meters. “People came to see the sea, its behavior. They were worried and it caused town, ”he recalls. Here, the sea is talking and Gérard Montassine has a good memory. The 79 -year -old man fished the gray shrimp from the 1960s to 1995. Son and father of sailors, he saw the pebbles go and the sea get closer.

When he was younger, he camped in the summer in the Hourdel dunes, before moving on his own boat. He was also a baller in the Baie de Somme, so that the Cabots spot themselves. “When I started, with the trawl, we were fishing 250 m from the dike. At the end, we went to 150 m. The sea, it advances. Without the restitution of Silmer, it would progress more. “He is a hell of a partner, a friend who participates in the balance of the coast,” says Thierry Bizet. For how long? The “pebble for pebble” restitution is not eternal. The careers where Silmer buys his stones to restore them to the sea have an estimated lifespan at thirty years. The alternatives do not convince.

An industry that is not unanimous

The cliffs of Boulogne-sur-Mer (Pas-de-Calais)? Sandstone, not flint. Maritime extraction? Environmental prohibitions must be taken into account. “Fortunately, Silmer does not do basic extraction intended for quantity” blows Thierry Bizet. The company has made it a slogan. “We are the Christian Dior du Galet,” likes to repeat Brigitte Pagès.

But in Cayeux, some less and less support the presence of an industry in the seaside decor. The transformation of pebbles generates dust, trucks pass at dawn … The city has 2400 inhabitants in winter and 20,000 in summer; 38 % of main residences and 62 % second homes. The tension rises. Recently, a Swiss bought a house close to the factory. He rents it on Airbnb. But vacationers complain about the noise. The owner launched a petition to reach neighbors, little followed. “Supreme injustice,” Brigitte Pagès moves. The worst for business chief: virulence of social networks. “People who have never set foot in Cayeux, who do not know us, and who dirty us with outrageous and lapidary remarks. »»

World mirror

In his office, Jean-Paul Lecomte, the mayor, knows the problem well. “I’m still in mediation,” he says. He too is concerned. The famous Cayeux beach cabins for example. Jean-Paul Lecomte wants to pass their number from 524 to 600. But the plank path must be extended, already the longest in Europe. Three resident buildings opposed it. Fear of losing sea view. Airbnb again. “I had to make a local referendum last year: 92 % yes”, lets go of the councilor, reeelled in 2020 with 68 % of the votes.

Behind these quarrels, a real risk. In Cayeux, being against the pebbles is to expose themselves. In April 2024, the Storm Pierrick surprised: at noon, nothing; At 2 p.m., 50 cm of water in the streets. “We live with it. But newcomers do not understand, ”says the mayor. They will understand. In 2026, three winters of works will start: Muret increased to 1.20 m, pit and water evacuation basins. Twelve million euros to anticipate the upcoming Centennale storm. “A nasty: we expect an Xynthia, it is planned in the models,” says Jean-Paul Lecomte.

Cayeux-sur-Mer is the mirror of the world. Here, the sea is a strength, a resource and a limit. It is not an isolated case, but a miniature of the world debate which opens in Nice with the Conference of the United Nations on the future of the oceans. The sea feeds: what are we ready to give it back?