They were once a symbol of devastation: black conical mountains rising in strange symmetry from the otherwise flat landscape of Nord-Pas-de-Calais, in northern France. Entirely made by humans, these terrils, or slag heaps, are the byproduct of nearly three centuries of coal mining in the region. Their presence is a reminder of both environmental and economic disaster, as the mines’ closure plummeted a region—already ravaged by industry—into unemployment and poverty.
Today the slag heaps (also known as spoil heaps) symbolize something else. What from a distance appears black turns green up close—the vegetation as promising as the sustainable tourism initiatives now starting to revitalize the region’s economy.
“The terrils are pockets of nature in a highly industrialized, urbanized area,” explains Frédéric Rivet, a naturalist-ranger at the Terril des Argales. Because of the soil’s heat, “they foster a biodiversity that wasn’t here before, attracting rare species like the European nightjar, and those usually found in a coastal marine habitat, like the natterjack toad, its mating call so loud you can hear it [about a mile] away.”
Now, these rehabilitated mounds serve as playgrounds for locals and visitors alike, with natural spaces and even the Louvre’s first satellite museum. Hikers appreciate the panoramas from the summits of Europe’s highest slag heaps, while ultra runners train on the “hell staircase” at the Arena Terril Trail in Noyelles-sous-Lens. Cyclists circle the lake at the Terril des Argales in Rieulay and skiers glide atop an artificial ski slope covering a terril in Noeux-les-Mines.
In Rieulay a vineyard blankets a slag heap, its Chardonnay grapes harvested by hand from steep terraces to produce the pride of the village: “Charbonnay,” named in a playful nod to charbon (coal). And in Loos-en-Gohelle, the former coal extraction site known as the Base 11/19 now serves as a tourist attraction, music center, and sustainable development hub. From the café operated by the tourism office, you can sign up for a range of activities on the terrils: an art therapy class, a meditation session, or a sunrise hike with breakfast.
“It’s nature’s revenge,” says Bernard Lefrançois, a former miner who guides tours at the Base 11/19. Beyond their function as natural spaces, the slag heaps also represent important industrial heritage. For Lefrançois, returning to his former workplace in a new tourism vocation inspires strong emotions and pride.
“I feel that I’m resurrecting the memory of the miners, particularly my father and grandfather, who died before the age of 60,” he says. “When I speak of the work underground, I always get chills … I cannot help but think of the toil, the sweat, the deaths. There are monuments to the memory of soldiers who died for France all over the country; the slag heaps, for me, are the national monuments to the miners.”
‘A crazy idea’
The French mining basin stretches about 75 miles west from the Belgian border, following coal seams far beneath the earth’s surface. At its widest, the swath measures only about 4.5 miles. But within this rectangular territory, nearly 2.4 billion tons of coal were extracted from the time coal was discovered in 1720 and the closure of the last mine in 1990. In fact, the region’s network of tunnels produced half of the French supply from 1940 to 1960, contributing to the country’s reconstruction after World War II. But the effects on the region were dire, the closure of the mines triggering a catastrophic economic collapse.
What to do in the aftermath? In this post-mining world, the initial impulse was to raze the slag heaps to the ground and plant them with vegetation, whatever the cost. “Helicopters flew overhead, dropping seeds, to cover up what was perceived as ugly black hills,” explains Jeremie Le Sage, a guide with Eden 62, an organization that manages and protects Pas-de-Calais’ natural sites (including 15 terrils). At the same time, inhabitants began to reappropriate the slag heaps, using them as motocross circuits and party spots.
In the early 2000s, a few visionaries imagined a new strategy for the future. After all, the destruction of the slag heaps would erase a page of history. “The miners are just as important as the kings in the history of France,” says Loos-en-Gohelle Mayor Jean-François Caron. Preserving this important heritage could also valorize it, giving the slag heaps a new purpose while safeguarding their unique biodiversity.
“It seemed crazy to talk of tourism in an industrial territory so scarred socially and economically, but certain politicians believed in it,” explains Cyrille Dailliet of the Mission Bassin Minier, the organization tasked with the area’s redevelopment.
Not all the terrils can be rehabilitated; some are still dangerous, and others are better left untouched as nature preserves. Aerial surveillance monitors some slag heaps’ combustion with infrared cameras. The Mission Bassin Minier has sought to create links between the terrils, mostly along the railroads that once transported coal, to serve as both nature corridors for fauna and recreational greenways for people.
In 2012 UNESCO awarded the mining basin World Heritage status, recognizing it as a living and evolving cultural landscape symbolizing Europe’s industrial history. The region’s infamous black mountains suddenly had the same standing as the pyramids of Giza. Shocked locals, newly instilled with pride, perceived their region differently.
In December of that same year, the long-planned Louvre Lens opened on a former coal mine in the town of Lens, its luxuriant gardens sprawling across a flattened slag heap. As the first outpost for the world’s most popular museum, the venue brought international cachet and great hope for the economic future. This year it’s celebrating its 10th anniversary with a packed program of events.
A nascent tourism ecosystem
Unemployment in Lens has been steadily decreasing since hitting a high of 15.5 percent in 2009. In the first third of 2021, despite the pandemic, the region recorded unemployment of 9.4 percent. Tourism businesses in the private sector are now following the large initial public investment. “We started at zero and we’re still in the beginning stages of a strategic approach for the tourism economy that will last decades,” says Dailliet.
Local entrepreneurs are starting to pop up with creative accommodations and experiences. In the village of Bruille-lez-Marchiennes, Françoise Hennebert opened a guest suite inside a custom-built wagon called la Roul’hôte. Created by an artisanal carpenter specializing in treehouses, this abode complements her ensemble of brick guest cottages. Near Lens, the stately former home of a mining engineer (the Maison d’Ingénieur) has been transformed into a local hangout with a restaurant and guest rooms.
At the Ferme des Chevrettes du Terril, situated at a former mining headquarters in Rieulay, Julien Graf and his wife Paola embarked on an adventure in sustainable agriculture that’s morphed into a tourist attraction. Their herd of goats grazes on the slag heap, thereby containing the vegetation in its pioneer state and preserving the biodiversity, while producing organic milk for cheese, soaps, and other products.
Julien’s brother Olivier operates a lively restaurant onsite where you can try the goat cheese and hearty regional specialties with local beer. The popular “rando biquette” (goat walk) allows visitors to join Julien on his daily transhumance across the terril, listening to his anecdotes and admiring the goats.
“These terrils are emblematic of the region,” says Graf, who’s originally from Douai. “Growing up, when we would come back from a trip and see the terrils from the highway, we knew we were home. Each of these rocks has passed through the hands of miners. If these terrils were covered in forest, we wouldn’t remember that.”