Fondry des Chiens

The Fondry des Chiens is a deep karst hollow near Nismes in the Viroin valley, a natural pit some twenty metres deep and a hundred long formed by the dissolution of the limestone along a fault and later opened up by iron ore working, with bare rock walls, ledges and pinnacles inside it and a floor of scree. Around it lies dry limestone grassland, tienne in the local term, an unusually rich habitat in Belgium that holds orchids, thyme, rock rose and a substantial butterfly list, kept open by grazing. The whole area is a nature reserve and the hollow is reached on a marked walking circuit from Nismes through the grassland. The name refers to iron ore extraction rather than to dogs, despite what the guides sometimes say.

What you actually see

• A twenty-metre karst hollow - bare rock walls and ledges in the grassland.
• Limestone grassland - orchids, thyme and rock rose on the slopes.
• Butterflies on the tienne - one of the richer sites in Belgium.
• The walking circuit from Nismes - the marked route through the reserve.

When to go

May to September, with June for orchids and July and August for butterflies. Two to three hours for the circuit. Weekends bring walkers. The rock is slippery when wet.

Honest expectations

Descending into the hollow is discouraged and the rock is unstable and slippery. It is smaller than photographs suggest. There is no shade on the grassland. Facilities are in Nismes rather than at the site. Ticks are present.

Nearby

Nismes and the Viroin valley are south; the Eau d'Heure lakes lie west.