La Grande Cournouse, from the Grotte de Pabro to the Pas de l'Allier

Departure from Châtelus town hall, reached from Pont-en Royan via the D292a shortly after starting to climb the Bourne valley.

(S/E) From the car park, walk 200 m back along the road to the south-east to the start of the tracks and paths.

(1) Take the track heading north-east, go through the barrier and, immediately afterwards, turn right onto the Pabro trail, which climbs quite steeply up the slope. At around 725 m, it joins a forest track which you take to the right for 100 m, then take the path again which branches off to the left for an uphill traverse towards the cliffs until you reach a crossroads with blue and red paint markings.

(2) The path on the left starts off level, descends slightly to go around a ridge, then climbs steeply up to the platform of the Pabro Cave.

(3) The path actually arrives in front of a large porch; the cave itself is on the right, down a short descent. After visiting the cave, which is not particularly difficult (there are boulders to climb over), return in the opposite direction to the crossroads.

(2) The path on the right (on the left when returning from the cave) climbs up a scree slope and then through a series of very steep corridors and ledges, sometimes earthy, sometimes rocky, where fixed ropes help you to pull yourself up with your arms. This is the Pas de Pabro, whose exit into the forest is marked by a cairn.

(4) You can go left to the rocks of Bec de Chatelus for an unobstructed view, then return to climb southwest on a pleasant forest track to its summit, where there is a viewpoint of the cliff a few metres to the right.

(5) Head east for a traverse that is sometimes level, sometimes ascending, leading to the summit of Pas des Voûtes.

Start climbing up opposite: at the first bend, a cairn marks the start of a path that first heads north-east, passing a viewpoint, then curves south-east to descend slightly below the cliffs to the prehistoric site of La Charmate, with its fountain.

(6) Retrace your steps to rejoin the forest track uphill, which immediately arrives at the junction with the Pas des Voûtes trail.

(7) Continue climbing along the forest track known as the Intérieur, which winds through the forest with flat sections and eventually reaches the Charmate viewpoint, the highest point of the day.

(8) Several trails connect this viewpoint to the Pas de l'Allier:
- continue along the forest track that descends eastwards until you reach the^GRP® du Tour du Vercors Drômois, which you take south then south-east to cross the plateau; this is the easiest but also the longest route.
- a trail starts near a marker to the south-west, staying on the Petite Cournouse ridge, then veers south-east to descend to Pas de l'Allier; this is the most direct route, but not the best marked on the ground.
- A good trail also starts in the south-east in the forest. It quickly descends to join another trail coming from the left and continues downhill to the GRP^®.

(9) Follow to the right to Pas de l'Allier; this is the GPS track route.

(10) From the viewpoint at the top of the cliffs, turn right onto the sunken path and then onto a remarkable retaining structure, which descends on the western side of the cliffs. The trail makes a long descent at the foot of the Petite Cournouse cliffs, with some eroded sections that can be tricky before they are repaired, to the foot of the Pas des Voûtes trail.

(11) Continue descending in the same direction along what is now a comfortable track until you reach the edge of the forest, near the Col de Mézelier.

(12) At Champ Gonet, altitude 565, turn right to climb up a path to the top of a meadow and turn left to go through a gate (make sure you close it behind you). Descend along a path between two fences, join a track and follow it for 100 m on the right, then turn left again and descend towards Châtelus, passing through a barrier just before reaching the road.

(1) Walk down the 200 m road back to the car park (S/E).

The Very Difficult rating is due to the Pas de Pabro climb, which is very steep and physically demanding. Only attempt this route in dry conditions.
The climb to the cave is also steep and difficult, but the rest of the route is of "medium" difficulty.

The descent of the Pas de l'Allier, which used to be well marked, is subject to rockfalls and landslides on part of the route: it is not uncommon for this section to be closed by municipal decree because the areas concerned are relatively exposed.
In this case (decrees posted at the relevant passages), it is advisable to descend via the Pas des Voûtes, from (7) to (11). It is quite steep but on a well-marked and signposted path.

There is a standpipe at the car park at the start of the walk, and water can also be found in the Grotte de Pabro at (3) and, above all, at the Charmate fountain at (6).

There are numerous viewpoints along the route as it winds between the western and eastern edges of the cliffs surrounding the Grande and Petite Cournouse.
The views are towards the Vernaison (Petits and Grands Goulets) or Bourne (Gorges) valleys, with either the Montagne de l'Arp or the Rochers de Presles opposite.

The Grotte de Pabro is vast and rich in concretions (especially stalagmites), some of which are unfortunately broken. Bring good lighting as the space is vast and has a high ceiling.