La Mer de Pierre

Hikers will enjoy discovering this "Mer de Pierre" (Sea of Stone) in the middle of the woods, recognised by specialists as a geological curiosity.
Gaining altitude in its first section, the walk offers wide views of the Guye Valley to the east and the Baudots area to the north. Very shaded, the route then offers a few glimpses of the Charollais Mountains.
See practical information.

Details

3105584
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  • Walking
    Activity: Walking
  • ↔
    Distance: 11.86 km
  • ◔
    Average duration: 4h 05 
  • ▲
    Difficulty: Moderate

  • ⚐
    Back to start: Yes
  • ↗
    Ascent: + 248 m
  • ↘
    Descent: - 248 m

  • ▲
    Highest point: 488 m
  • ▼
    Lowest point: 238 m

Photos

Description of the walk

Park at the Parking des Randonneurs on the right after the church, just before the Guye bridge

(S/E) Leave the car park and turn left onto Rue de l'Église until you reach the D983. Turn right onto the departmental road, then 100 m further on, carefully cross this relatively busy road and turn left onto Route de Santagny.

(1) Immediately turn right and walk along Place du Marché.
Continue straight ahead on Rue du Teurcet before turning right a little further on Rue des Chênes. Pass the houses and you will soon reach a four-way crossroads.

(2) Turn left and follow the path between fields and pastures for 1 km until you reach a road near the village of Santagny at a stone cross.

(3) Turn right for a few metres, then immediately turn left onto another road towards Les Volans. Soon leave the road that turns right and continue straight ahead on an irregularly maintained grassy path. Stay on this path, which climbs for about 700 m before coming to a perpendicular path.

(4) Turn right and rejoin the road a little further up at a place called Les Fourneaux. Turn left and stay on the road to reach the Ferme des Volans just after being joined by theGR®7coming from the right.

(5) Keep left to follow theGR® and walk alongside the farm buildings before reaching the forest, 600 m after the farm, at a four-way crossroads.

(6) Keep following theGR® trail, then ignore a path on the left. A little further on, the trail splits into two branches. Keep left to stay on theGR® trail and cross a very ravined area for about 200 m before joining the other branch of the trail coming from the right.
Continue along theGR® for about 50 metres before leaving it and turning south onto the first path on the left. Ignore the cross paths and continue to an intersection at the Totem de la Mer de Pierre.

(7) Keep to the left and continue south towards Chaleutre. After about 100 m, make a short detour to the right to enjoy a panoramic view of the site. Be sure to return to the trail and continue south. Follow a slightly unclear passage between the rocks and you will soon find the Mer de Pierre sign at the southern end of the site.
The path is on the left. Continue south and you will reach the forest. Pass "la Pierre qui tient l'eau" (the stone that holds the water) and you will soon reach the Chaleutre crossroads.

(8) Follow the path that veers to the right and you will reach a four-way crossroads near Le Télégraphe.
Continue straight ahead for about 200 m until you reach a fork. Leave the path that turns right and veer left to start descending southwards.
Ignore the path on the right and stay on the path that gradually turns left until you come to a wide crossroads in a clearing.

(9) Turn right and continue south. Pass the first house on the right before reaching a fork at a farmhouse. Turn left just before the farmhouse.
Ignore the start of another path on the left and continue downhill towards the east. After two sharp bends, you will see a view of Collonge-en-Charollais on your right.
Soon after, you will pass a ruin before reaching another intersection.

(10) Leave Chemin des Teppes on your right and continue straight ahead. Keep to the right at the next two intersections. Cross a pasture and return to the woods at a four-way crossroads.

(11) Turn left onto a beautiful forest path lined with oak trees. Stay on this path heading north and keep to the right when you reach a fork. You will soon cross the Sentier de la Résistance.

(12) Continue straight ahead and join another path 400 m further on. Turn left and you will soon reach a four-way crossroads, still in the forest. Continue straight ahead north then north-east until you reach a cross path. Turn left onto this path before turning sharply right to leave the woods.

(13) Turn completely right and walk along the crops towards the east until you reach a place called Les Gaillets.
After the buildings, continue along a tarmac road which soon turns left to join a main road. Continue straight ahead and you will soon reach the next crossroads.

(14) Turn right towards the village and rejoin the D983 at the end of the road. Cross very carefully and follow the departmental road to the left for a few metres before turning immediately right at No. 39. Continue along the house, take a footbridge over the Guye and arrive at the Hôpital crossroads.
Continue to the left and return to the car park at the Old Bridge (S/E).

Waypoints

  1. S/E : km 0 - alt. 240 m - Hiker car park after the church. At the edge of the - Guye (rivière)
  2. 1 : km 0.38 - alt. 248 m - Fork in the road
  3. 2 : km 1.02 - alt. 264 m - Four-way intersection
  4. 3 : km 1.97 - alt. 294 m - Stone cross in Santagny
  5. 4 : km 2.87 - alt. 345 m - Fork in the road
  6. 5 : km 3.68 - alt. 413 m - Ferme des Volans
  7. 6 : km 4.33 - alt. 421 m - Crossroads at the edge of the woods
  8. 7 : km 5.08 - alt. 470 m - Totem of the Mer de Pierre
  9. 8 : km 5.74 - alt. 485 m - Chaleutre crossroads
  10. 9 : km 6.81 - alt. 414 m - Clairière: T-junction
  11. 10 : km 7.65 - alt. 324 m - Intersection near the ruins
  12. 11 : km 8.03 - alt. 297 m - Crossroads of the four paths
  13. 12 : km 8.48 - alt. 308 m - Sentier de la Résistance junction
  14. 13 : km 9.49 - alt. 275 m - Exit from the woods
  15. 14 : km 10.5 - alt. 263 m - Genouilly: Four-way intersection
  16. S/E : km 11.86 - alt. 240 m - Hikers' car park after the church.

Notes

There are a few places where you could get lost. It's best to be familiar with reading a map, but of course, with a GPS (or the Visorando app), there's no need to worry.

Worth a visit

Always be cautious and plan ahead when you're outdoors. Visorando and the author of this route cannot be held responsible for any accidents occurring on this route.

The GR® and PR® markings are the intellectual property of the Fédération Française de Randonnée Pédestre.

Reviews and comments

4.3 / 5
Based on 8 reviews

Reliability of the description
4.6 / 5
Ease of following the route
4.5 / 5
Route interest
3.9 / 5
User 9056917

Overall rating : 4.7 / 5

Date of your route : Jul 13, 2025
Reliability of the description : ★★★★★ Very good
Ease of following the route : ★★★★★ Very good
Route interest : ★★★★☆ Good
Very busy route : No

Once you reach the stone sea, the view of the valley is splendid.
The problem with this hike is that part of the path between points 12 and 13 is private property. The path may even be closed at point 13.

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Philippe BARRIER
Philippe BARRIER

Overall rating : 4.3 / 5

Date of your route : Apr 11, 2025
Reliability of the description : ★★★★☆ Good
Ease of following the route : ★★★★★ Very good
Route interest : ★★★★☆ Good
Very busy route : No

A varied hike with beautiful views. The elevation gain along the proposed route is very gradual and can be done with children. Contrary to what has been mentioned in previous reviews, "La Mer de Pierre" is worth seeing and remains very mineral in appearance! An unusual place.
A word of caution: between points 9 and 10, at the edge of the woods at altitude 380 on IGN maps, the route passes close to an isolated house resembling a scrapyard with two ferocious-looking dogs in the enclosure. However, the fence is not secure at the gate and the dogs can get underneath it. If you are with children, this could be very tricky (and that's putting it mildly). They came close to me, baring their teeth, but nothing more. Be careful! Otherwise, no worries.

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sguillard69
sguillard69

Overall rating : 4 / 5

Date of your route : Oct 21, 2024
Reliability of the description : ★★★★☆ Good
Ease of following the route : ★★★★☆ Good
Route interest : ★★★★☆ Good
Very busy route : No

A pleasant little hike, the stone sea is still clearly visible even though there is more and more greenery!

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celine974r
celine974r

Overall rating : 4 / 5

Date of your route : Jul 20, 2024
Reliability of the description : ★★★★★ Very good
Ease of following the route : Not used / Not applicable
Route interest : ★★★☆☆ Average
Very busy route : No

A bit disappointed with the Mer de Pierre because the vegetation has taken over quite a bit. It's still a nice little hike for locals.

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celine974r
celine974r

Overall rating : 4 / 5

Date of your route : Jul 20, 2024
Reliability of the description : ★★★★★ Very good
Ease of following the route : Not used / Not applicable
Route interest : ★★★☆☆ Average
Very busy route : No

A bit disappointed with the sea of stone because the vegetation has taken over quite a bit. It's still a nice little hike for locals.

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Serge71100
Serge71100
• Edited:

Overall rating : 4.3 / 5

Date of your route : Feb 05, 2024
Reliability of the description : ★★★★☆ Good
Ease of following the route : ★★★★★ Very good
Route interest : ★★★★☆ Good
Very busy route : No

A very pleasant hike with no particular difficulties. We did this hike in early February, and there were hunters in the woods we crossed.

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merlin patrick
merlin patrick

Overall rating : 4.3 / 5

Date of your route : Oct 16, 2023
Reliability of the description : ★★★★★ Very good
Ease of following the route : ★★★★☆ Good
Route interest : ★★★★☆ Good
Very busy route : No

Very beautiful hike.
The stone sea is superb.

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Vincs
Vincs

Overall rating : 4.7 / 5

Date of your route : Oct 09, 2023
Reliability of the description : ★★★★★ Very good
Ease of following the route : ★★★★☆ Good
Route interest : ★★★★★ Very good
Very busy route : No

A pleasant hike with beautiful views. The first part is open, then shaded.

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