Heading back up towards the source of the Tronne

A small stream originates in a place called Bausdisson.
It flows through the town from north to south and joins the Loire after a journey of around twelve kilometres.
This small river, called the Tronne, gives the town of Mer a certain charm.
In fact, Mera means "marsh" or "place covered with water" in Latin, which is the origin of the name Mer.

Details

22968087
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  • Walking
    Activity: Walking
  • ↔
    Distance: 9.36 km
  • ◔
    Average duration: 2h 45 
  • ▲
    Difficulty: Moderate

  • ⚐
    Back to start: Yes
  • ↗
    Ascent: + 30 m
  • ↘
    Descent: - 30 m

  • ▲
    Highest point: 99 m
  • ▼
    Lowest point: 80 m
  • ⚐ Country: France
  • ⚐ District: Mer (41500)
  • ⚑
    Start/End: N 47.704207° / E 1.507956°
  • ❏
    IGN map(s): Ref. 2120O, 2121OT, 2121SB
  • Hour-by-hour weather

Photos

Description of the walk

Park in the car park in front of the Halle aux Grains de Mer, Avenue Maunoury.
Signposting: Blue or yellow, continuous line or circle

(S/E) Walk up Avenue Maunoury towards the station. Cross towards the station entrance, continue on the left and take the tunnel under the tracks. Walk down towards the park, follow the wooden footbridge on the right after the first small bridge.
At the signpost, follow the signs for La Tronne, marked with a circle. At the end, turn right, take the stairs and continue left into Impasse des Pichoteries.
Go up Rue Gilbert Philippe and join Rue Haute d'Aulnay.
Turn right and cross carefully towards Rue des Brossillons.
On the left, take Chemin des Fourneaux. At the end of this road, cross Rue de Buray and take the road opposite.
Reach Rue Haute d'Aulnay, cross the road, take care. Turn right, continue along Grande Rue, go up this street towards the water tower. Take care as you continue on the left-hand side of the road. Reach the Source de la Tronne crossroads.

(1) Turn left at a large gate, at a place called Fontaine de Baudisson, go down to admire the Source de la Tronne, and go back up the stairs. Turn left onto a grassy dirt track until you reach a place called Les Grandes Maisons.

(2) Take Rue Basse d'Aulnay, before the cemetery, pass through the garden of the Chapelle d'Aulnay, take the path below, turn left and go down a grassy path, turn right before a footbridge and follow the path along the edge of the Tronne. You will reach the Simon Hémé nursing home.

(3) Walk along it to reach the crossroads with Rue Cour du Moulin. Turn right onto it, then continue along the path that follows it. Then turn right onto Rue Gilbert Philippe, then left onto Rue Basse d'Aulnay. Leave it on the right and take the alley on the left between the houses, follow the lane to the end, turn right, join Rue Basse d'Aulnau and go up towards the Mérolles school.
Follow a grassy path, turn right, then right again towards a car park.
At the end, turn right and join Rue Pierre Loison, heading towards an aqueduct.
Follow the yellow continuity markings, take an alley on the left immediately after passing the aqueduct, cross Rue Bizeray with caution, turn right and follow the river to a footbridge. Follow the yellow round markings. Cross Rue Toutevoie and take Rue de la Fontaine.
Turn left onto Rue Dutemps, then right onto Rue des Pichots.
Return to Avenue Maunoury, turn right before the traffic lights and continue to Place du Novembre 1918.

(4) Pass in front of the statue of General Maunoury, go down a few steps, cross the road and continue straight ahead, on the left, passing under a porch.
Cross Route Nationale D152 with caution and continue along Rue Barreau. On the left, go up Rue des Coteaux to the tower in the town hall courtyard. Cross the road with caution. Opposite, take the narrow streets to Rue Jean Moulin. Follow the yellow markings. Cross Rue Barreau and take the alleyway opposite. Continue to Parc de la Corbillière and climb up to the museum. Admire the remarkable Lebanese cedar tree, then descend towards La Tronne.

(5) Cross the D152 national road again at Place de l'Église, take the pedestrian street Rue Jean et Guy Dutems, turn right onto Rue Lenoir, take an alley on the left, Rue de Pichots, do not go up Avenue Maunoury. Turn left again to rejoin the same semi-pedestrian street via Rue des Moines.
At the end of Rue Dutemps, cross towards a car park, turn right, admire the statue of the goddess Ceres, cross the park towards the market hall, follow the signs to reach the Halle aux Grains car park (S/E).

Waypoints

  1. S/E : km 0 - alt. 94 m - Car park at the - Halle aux grains
  2. 1 : km 2.82 - alt. 95 m - Source of the Tronne (river) - Tributary of the Loire - la Tronne
  3. 2 : km 3.82 - alt. 96 m - The Great Houses
  4. 3 : km 4.47 - alt. 87 m - Nursing home
  5. 4 : km 6.92 - alt. 91 m - Place du Novembre 1918
  6. 5 : km 8.5 - alt. 87 m - Gentilhommière de la Corbillière (Sea) - La gentilhommière de la Corbillière - Musée
  7. S/E : km 9.36 - alt. 94 m - Car park at the - Halle aux grains

Notes

Access: A10 exit 16 - D2152 from Blois or Orléans - Train: SNCF station.
Numerous parking spaces around the Halle, Avenue Maunoury, the station. Toilets: Place de la Halle.
Parc de la Corbillière - Opposite the church.
Food: Pizzeria - Maison Marchand.
Bars and cafés in the town centre.
Accommodation: Numerous lodges and guest rooms.
Local shops.
Facilities: public toilets at the Halle, Parc de la Corbillière and the church.

Worth a visit

Along the way:
The Halle aux Grains, etc.
Viewpoint not to be missed: The Temple

Reviews and comments

4.7 / 5
Based on 6 reviews

Reliability of the description
4.8 / 5
Ease of following the route
4.7 / 5
Route interest
4.7 / 5
emma41
emma41

Overall rating : 5 / 5

Date of your route : Nov 04, 2025
Reliability of the description : ★★★★★ Very good
Ease of following the route : ★★★★★ Very good
Route interest : ★★★★★ Very good
Very busy route : No

We went hiking with our club 15 days ago.
To get to the source, there were more than 40 of us.
We didn't take the upper road from Aulnay, but instead took Rue de la Babin to reach the lower road from Aulnay.
We made the round trip through the fields.
This time, we were able to follow the Tronne river along the entire route, which was wet but passable.
For many, it was a pleasant discovery of the alleys and the Tronne in the sunshine.
Thank you for sharing the hidden sides of Mer with us.
Emma

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emma41
emma41

Overall rating : 5 / 5

Date of your route : Jul 22, 2025
Reliability of the description : ★★★★★ Very good
Ease of following the route : ★★★★★ Very good
Route interest : ★★★★★ Very good
Very busy route : No

Hello,
We went hiking yesterday morning, which was the ideal weather for walking.
After the Aulnay chapel at point 2, we reached La Tronne only via Rue des Blés d'Or.
The path was impassable. A local resident explained that it had been flooded and could not be maintained.
This allowed us to discover the town, La Tronne up to its source, and the residential areas.
Thank you for the route and the detailed description.
Emma

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lemaire marie brigitte
lemaire marie brigitte

Overall rating : 4.3 / 5

Date of your route : Dec 09, 2024
Reliability of the description : ★★★★☆ Good
Ease of following the route : ★★★★☆ Good
Route interest : ★★★★★ Very good
Very busy route : No

The signposting is well done. Due to the stream flooding, some sections are difficult. We had to go back up to the road, leaving the grassy paths, but it was refreshing and peaceful, thank you.

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Lauthi
Lauthi

Overall rating : 4.7 / 5

Date of your route : Jan 29, 2024
Reliability of the description : ★★★★★ Very good
Ease of following the route : ★★★★★ Very good
Route interest : ★★★★☆ Good
Very busy route : No

An interesting and varied hike. It allowed us to discover Mer and its hidden treasures. A pleasant surprise.

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randovaldemer41
randovaldemer41

Hello,
Thank you for your feedback and for sharing the images.

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sholby
sholby

Overall rating : 5 / 5

Date of your route : Dec 25, 2023
Reliability of the description : ★★★★★ Very good
Ease of following the route : ★★★★★ Very good
Route interest : ★★★★★ Very good
Very busy route : No

On Christmas morning, I only did the northern half of the hike, from the centre of Mer to the source of the Tronne.
I found the route, although inevitably muddy at this time of year, very interesting and varied. Of course, there wasn't a soul in sight, but I did see storks, sheep, goats, horses and even a black rabbit. The route winds along the Tronne to the amusing source, passing through the town's streets, alleys, paths, small bridges and industrial areas. In short, there's something for everyone...
It gives a more mysterious view of Mer than a simple walk through the town centre.

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Aurmi
Aurmi

Overall rating : 4.3 / 5

Date of your route : Jul 31, 2022
Reliability of the description : ★★★★★ Very good
Ease of following the route : ★★★★☆ Good
Route interest : ★★★★☆ Good
Very busy route : No

I didn't know this little river, the Tronne, but this walk allowed me to discover it and realise that there were still mosquitoes!
The route is a little less pleasant before reaching the source, near the water tower, but there's no way around it.
Overall, it's a lovely little walk.

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