Former Anjou slate-quarrying site at La Pouëze with a surviving wooden headframe over puits no. 3, inscribed as monument historique in 1999, set within a heritage landscape of spoil heaps and open-cast workings.
The ardoisières de La Pouëze in the commune of Erdre-en-Anjou (Maine-et-Loire) form part of the Anjou slate basin, whose vein extends from Trélazé through Saint-Barthélémy to Avrillé and northwards. Open-cast extraction on the western side of the commune is documented from the fifteenth century, and small underground workings were established by the early nineteenth century. Industrial-scale extraction developed through the nineteenth century, initially as open-cast quarries and later as underground mines served by vertical shafts equipped with headframes of the same type as those used in coal mines.
The principal sites are grouped north-east of the village of La Pouëze. Puits no. 1 (la Carterie) reached 101 metres but was destroyed by fire in October 1899. Puits no. 2 followed.
In 1941 puits no. 3 was deepened and a supplementary shaft (3bis) was sunk; this complex sustained the centre ardoisier until 1989 when a rockfall condemned the Carterie site. The wooden headframe over puits no. 3, reaching approximately its present form by the mid-twentieth century, was inscribed as monument historique in March 1999. The industrial workings of the Espérance site have ceased; the landscape retains prominent spoil heaps, the puits no. 3 headframe, administrative buildings, and workers' housing.
Small-scale open-cast slate workings on the commune of La Pouëze are attested from the fifteenth century, located at La Pinardière and La Bichetière toward Vern-d'Anjou. By 1797 three artisan families from Saint-Quentin-les-Anges — the Chesneaux, Gasnier, and Bellanger households — had settled at La Pouëze to continue slate working after the closure of a small ardoisière at Chatelais. Between 1800 and 1830, exploitations belonging to petits maîtres employed approximately ten workers each. An 1894 estimate gave annual production of 3 million slates with 110 workers.
Industrial extraction developed through the nineteenth century by sinking vertical shafts equipped with headframes on the same model as those used in coal mines. The principal workings were grouped north-east of the bourg at the Carterie and Fiogée sites. Puits no. 1 (la Carterie) descended to 101 metres; it was destroyed in October 1899 when a steam-powered extraction machine installed at the shaft vault caught fire and set the timbering alight, causing the puits to be abandoned. Following this catastrophe, extraction was renewed entirely and puits no. 2 was sunk at la Carterie.
In 1941, facing exhaustion of the shallower reserves, the operators decided to commit fresh capital: puits no. 3 was deepened and a rescue shaft, puits 3bis in reduced section, was driven at la Carterie. By 1952 the centre ardoisier was operating with approximately 300 workers, accounting for some 4% of the national output in quality slates. By 1980 the workforce had fallen to 140. In 1968 puits no. 3 was replaced for principal extraction purposes by the deepened puits 3bis (equipped with a steel headframe), which was driven to 450 metres; puits no. 3 was epuisé at 355 metres and abandoned in 1974. The steel headframe of puits 3bis was demolished at the end of the 1980s. In 1989 a rockfall condemned the Carterie site entirely. Slate working at La Pouëze continued for a further period using stone transported from Trélazé and Noyant-la-Gravoyère/Misengrain, before ceasing definitively in 1998 with the end of the Société des Ardoisières de l'Anjou.
The surviving wooden headframe, standing over puits no. 3, is a landmark in the local landscape. Puits no. 3 had been completely abandoned since 1974. The chevalement en bois of puits no. 3 was inscribed to the Inventaire supplémentaire des Monuments Historiques by arrêté of 16 March 1999. Other surviving elements at the Espérance site include the administrative building with brick window surrounds, the patron's residence dated 1897, and the workers' housing estates of La Fiogée and Les Pouëzettes. The landscape is strongly marked by former open-cast quarries and spoil heaps of slate waste. A heritage discovery trail around the site de l'Espérance was developed by the commune and provides interpretation of the mining heritage.
