Sentier Karstique du Grand Bois

Sentier Karstique Montrond-le-Chateau - Grand Bois de Mérey

Useful Information

Location: Near Mérey-sous-Montrond, Jura. From Mérey-sous-Montrond follow D11 towards Fontain, parking about 1.5 km north of Mérey-sous-Montrond. Signposted.
(47.161088, 6.061274)
Open: No restrictions.
Guided Tours: JUN Sat, Sun 14, 15:30.
JUL to AUG Mon-Fri 10:30, 14, 16, Sat, Sun, Hol 10:30, 14, 15:30, 17.
Fee: free
Guided Tours: Adults EUR 5, Children (11-18) EUR 4, Children (0-9) free, Students EUR 4, Speleologists EUR 4.
Groups (10+): Adults EUR 4.
Classification: TopicSentier Karstique KarstCovered Karst KarstDoline KarstKarren SpeleologyKarst Cave KarstCollapsed Cave KarstLimestone Pavements
Light: bring torch.
Guided tours: self guided, L=1,200 m, D=45 min.
guided, L=1,600 m, D=
Photography: allowed
Accessibility: no
Address: Sentier Karstique du Grand Bois, Mairie de Mérey-sous-Montrond, 1, rue Saint-Sébastien, 25660 Mérey-sous-Montrond, Cell: +33-680-14-46-41, Fax: +33-381-86-79-14.
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
Please check rates and details directly with the companies in question if you need more recent info.


2001 start of summer camps for the restauration of the trail.
2005 restauration completed.


The Sentier Karstique du Grand Bois (Karst Trail of the Great Forest) or Sentier Karstique Montrond-le-Chateau near the village Mérey-sous-Montrond is a special sight. On one hand it is a geologic gem showing numerous typical and rare features of karst areas, on the other hand it is a mysterious realm of elves and dwarfs. The Grand Bois de Mérey (Great Forest of Mérey) is a fantastic realm of dark trees, lichen, and moss.

A winding path starts at the parking lot at the road and runs into the forest. It is a round trip, and it will end at the same place, but in between the visitor will lose his direction completely. The path crosses bridges, orbits around collapsed caves and crosses small caves. The whole trail is inside an enchanted forest, and even the sun is not able to tell you allways which direction youre going.

The main sights of this trail are small caves, sinkholes and dolines. Other, not so obvious karst features are karren, limestone pavements and other solutional forms. The rocks form strange formations, looking like rugged ruins, the remains of medieval castles or huge fungi, several metre high. All those forms are a result of the weathering of limestone and thus strongly connected with the forming of karst.

Even the plants and animals of the forest are affected by the geologic situation. The karstified rocks allow the water to easily enter vaults and so the whole forest has no running water, very few dolines form small lakes, as they are filled with watertight clay. But the whole ecosystem is adapted to the lack of water in a humid area, where rains are rather common. The trees, the fungi and the mosses work together to keep the water in the top soil as long as possible, in order to survive periods of sunny weather.

The whole community of plants in this forest is adapted to the special conditions of covered karst in humid areas. The whole system is able to survive, but a human interference, especially the chopping down of trees would destroy the fragile eco system, and allow erosion to move the soil away and leave a rocky desert, a bare karst region.

The Grotte Maëva is one of the caves along the trails, and it is not possible to visit it self-guided. A few years ago the small cave (30 m long) was actually developed into a show cave. Trails and electric light were installed. When taking the guided tour through the karst trail, the visit of the cave is included.