A dramatic journey through time and some spectacular stalactite formations, the Grottes de Thouzon can be found 16 km / 10 miles east of Avignon, just outside the small town of Thor.
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The site was first discovered in 1902 when workers at a neighbouring limestone quarry were detonating explosives. They were mightily surprised and impressed at what they found.
Today the entrance, by a modest snack bar, belies the spectacle inside. The geologically minded will identify all sorts of formations: stalagmites, draperies (curtains of stalactites), gours and neat, round cave pearls.
The most striking sight is the thousands of fistulous stalactites, sometimes called macaroni because they're hollow. These pale, delicate, fragile fingers can be up to two metres / six and a half feet long and less than three millimetres / one-eighth of an inch thick.
The Grottes de Thouzon are also sometimes known as the Grotte aux Fées, or Fairy Cave and younger kids should enjoy these magical shapes and colours, ranging from pure white to - thanks to the presence of iron oxide - orange, rust and brown.
At the climax of the visit, the tour recreates, with dramatic lighting and music, the thrilling moment back in 1902 when those quarrymen first discovered the cave by candlelight.
The cave dates back to the cretaceous geological period, which makes it at least 60 million years old (by the way, although both the promotional literature and website refer to "caves" in the plural, the site consists of one very long thin cavity).
The main attraction for families is that, unlike most underground caves in the region, which are stacked vertically and require potholing skills, Thouzon is a horizontal series of formations.
The trail path gently follows the fossilised bed of the Sorgue river which once ran through the cave, and is easily accessible. It's the only cave of this type in Vaucluse that's open to the public.
The path is 230 metres / 250 yards long, and so not huge. The guided tour lasts a brisk 45 minutes, which might be a disappointment for some but could well be an advantage for those travelling with small children. Comfortable flat shoes are advised, as is a light sweater, as it's a humid and cool 13 degrees Celsius / 56 degrees Fahrenheit inside, even in high summer.
There are limited tours in English on request, but if one isn't available you can always take a leaflet in one of six languages, including English, at the reception desk, even if this doesn't offer quite the same experience.
Thouzon also has a shop selling rock and mineral samples, jewellery and other small souvenirs, a picnic area and snack bar and free parking. It's closed between early November and February.
Where: Grottes de Thouzon, 2083 route d'Orange (D16), 84250 Le Thor. Tel. (+33) 4 90 33 93 65. Website for the Grottes de Thouzen
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