Printed from: on 23 Aug 2017
Copyright: © 2017 - 2017 John Gardner

Réseau de la Dent de Crolles
Photograph of the main passage in the lower story of Trou du Glaz
Note the dip of the strata running down from right to left
Photograph: Dave Checkley


The Dent de Crolles is part of an extensive Early Cretaceous limestone massif in the Chartreuse range of the French prealps, with its summit of 2062 metres looming over the Isère valley. It is honeycombed by a cave system with over 60 km of passages contained within an area of just 2.3 km². The Réseau de la Dent de Crolles has eleven entrances, including the resurgence (Grotte du Guiers Mort, 1332 m) and a top entrance (Gouffre Bob Vouay, 2026 m) which is located just 160 m from the summit. It is made up of a number of active systems draining into a master cave, and a number of far older large fossil phreatic systems. These were probably formed during the mid-Pliocene, and drained a landscape long since disappeared. The fossil passages were truncated during the Quaternary glaciations, and now have large entrances overlooking deep valleys on the east, west, and north sides of the massif. They have been intercepted by the active systems to create a vast interconnected network, the plan survey which has been likened to a plate of spaghetti.

Dent de Crolles plateau and summit from the south

Dent de Crolles plateau and summit from the south
The highest entrance is near the col left of top centre, and the resurgence is near bottom right
Click image for larger resolution

The Réseau de la Dent de Crolles provides perfect holiday caving, with a large number of through trips and round trips possible of varying degrees of difficulty. It is possible to traverse from the top of the mountain to near the base, and through the mountain from west to east, and combinations of the two. Some of the more popular routes have been superbly equipped with pull-through chains and traverse lines, and are waymarked. Some of the through-trips take around 4 hours, others over 12. All the entrances are reasonably accessible, the walk-in varying between about ¾ of an hour, and two hours.

The purpose of this website is to pull together the latest pertinent information on the cave, and to clarify the locations of the entrances. Please look at the Sources of information page for a summary of available material, much of it on the web.

As of 2017 the following 11 entrances are known. Those with links are discussed further on this site.

Name Northing Easting Altitude Notes
Gouffre Bob Vouay 3 45.30960° 5.85445° 2,026 m 100 m from the summit, links with Trou du Glaz and Grotte Chevalier
Gouffre des Quanta 5 45.316° 5.865° 1,937 m About 210 m E of S of Gouffre Thérèse, links with Guiers Mort
Accessed by a 50 m abseil down the eastern cliffs!
P40 1 45.31259° 5.85357° 1,930 m Equipped route to Trou du Glaz
Gouffre Thérèse 1 45.31821° 5.86458° 1,925 m Equipped route to Grotte du Guiers Mort
Gouffre Pulpite 3 45.31407° 5.85586° 1,901 m Equipped route to Trou du Glaz.
Links with Grotte du Guiers Mort
Puits des Cartusiens 2 45.32081° 5.86179° 1,780 m Links with Grotte du Guiers Mort
Grotte des Montagnards 5 45.310° 5.856° 1,765 m Entered and linked with Grotte Chevalier in 1966
Accessed by an 80 m hard rock climb on the eastern face.
Trou du Glaz 2 45.31736° 5.85146° 1,697 m Equipped routes to Guiers Mort, Annette Bouchacourt, and Chevalier.
Exit for equipped routes from P40 and Gouffre Pulpite.
Equipped round trip.
Grotte Annette Bouchacourt 4 45.30710° 5.85540° 1,685 m Exit for equipped route from Trou du Glaz.
Grotte Chevalier 4 45.30766° 5.85616° 1,670 m Exit for equipped route from Trou du Glaz
Links with Gouffre Bob Vouay
Grotte du Guiers Mort 4 45.32591° 5.85727° 1,332 m Exit for equipped routes from Trou du Glaz and Gouffre Thérèse.
Also links with Gouffres Quanta, Cartusiens, and Pulpite.
Two equipped round trips.
1  Location from Spéléo Secours Isère route guide
2  Location from Gilbert Bohec's survey
3  Location from author's GPS reading
4  Location from IGN map 3334OT
5  Location estimated from Gilbert Bohec's survey
Dent de Crolles from the west showing 7 of the 11 entrances

Dent de Crolles plateau from the west showing seven of the entrances. The other four are in the eastern cliffs
Click image for larger resolution

In addition to the caving, the area also offers magnificent walking, as well as ample opportunities for big route climbing, sport climbing, canyoning, and via ferratas. For more information on the area consult the author's Chartreuse website.