The Troche Quarry and Lake Lozère

Starting point and access: Orsay-Ville station.
- RER - Line B, on the section between Paris and Saint-Rémy-lès-Chevreuse.
Take Exit 2 Rue de l'Yvette/Faculté, on the side of Platform 2, travelling from Saint-Rémy-lès-Chevreuse to Paris (if arriving in the opposite direction, Platform 1, use the underpass).

No signposting

(S/E) On leaving the station, head diagonally left onto Rue Élisa Desjobert. Walk downhill, cross Rue de Launay and continue straight ahead. At the crossroads, take the footbridge over the Yvette.

Red and white markings

As you come off the footbridge, turn right and follow the river. Pass the municipal swimming pool on your left and turn right to cross the river again.

No markings

You’ll emerge at the edge of Lac du Mail; go round it on the left. At the end, follow a street to the left for a few dozen metres.

(1) Take a narrow footbridge to cross the Yvette again (do not go under the railway bridge). Cross Avenue de Lattre de Tassigny and continue straight ahead, uphill, along Avenue des Bois. At the junction, take the^first right (dead end). At the end, turn left onto a narrow path and follow the railway line on your right. Continue along a narrow lane (Impasse de Verdun), still following the railway line. At the end, turn right onto Rue de Verdun and follow it to Guichet station.

(2) Then turn left and immediately right at the corner of a restaurant. Follow Rue du Guichet and cross the N118. When the street turns right towards Palaiseau, turn left onto Rue Aristide Briand. At the fork that appears immediately, turn right onto Rue de Corbeville and then immediately right onto Montée de la Glycine. Climb this steep path, interspersed with steps, which ends in a flight of stairs.

Yellow markings

At the top, follow a street to the left. After about 75 m, climb another flight of steps on the right.

No markings

At the top, continue straight on along Rue Fernand Couturier to the end of the road. Then turn left and you will immediately find the entrance gate to the Bois de la Troche on your right.

Yellow markings

(3) Go through the gate and go down a wooden staircase. Continue downhill and you will soon reach the old Troche quarry (sandstone rocks, climbing school). Turn right, cross the sandy area, continue along a dirt track and go under a footbridge (ground may be wet). At a fork, veer to the right. Turn right with the path, pass through a metal gate and rejoin the tarmac.

No signposting

At the end of the street, turn left. After about 50 metres, turn right into Rue de la Troche.

(4) After a few metres, head straight on into the Passage du Rocher and go down these steep steps. At the bottom, turn left. Immediately ignore a yellow arrow pointing left onto the Sentier de Châteaufort and go down Rue des Gâtines. At the end, turn left. At number 117, turn right onto a footpath and take the footbridge over the railway line. On the other side, follow Rue de Lozère to the left.

(5) At the three-way junction, follow Rue Béranger to the right (access to Lozère station on the left). At the three-way junction, turn left, still on Rue Béranger. At the crossroads, take the^first right, at an acute angle (Rue Alfred de Musset, not signposted here). At the next junction, turn left, cross a road and pass through a wooden gate to reach the eastern end of Lac de Lozère. Take a path between the Yvette (on your left) and the lake (on your right). At the end, take a footbridge on the left to cross the river.

Red and white + yellow markings

(6) Follow the Promenade de l’Yvette to the right. After a football stadium, at a junction, continue straight on, as the tarmac gives way to a hard-packed track. Pass through a forest gate and emerge at a roundabout.

Red and white markings

(7) Go straight on (ignore the PR® turning left) and cross the^first slip road onto the N118 at the pedestrian crossing. Pass under this four-lane road and cross a^second slip road. Continue along the river and, just before a 30 km/h zone, head for the riverbank. Go under a small road bridge. Further on, join the road, follow it to the right and go under the railway viaduct.

(1) Ignore the narrow footbridge on the right that you took on the way there; head towards Lac du Mail and go round it on the left.

No signposting

At the corner of a playground, turn left. Follow Rue du Mail straight on and cross Rue de Launay. At the end, turn right onto Rue de l’Yvette. After about fifty metres, you’ll find the entrance to Orsay-Ville station on the left (S/E).

To get back home:
- RER - Line B, towards Paris (direct access to platform 2) or Saint-Rémy-lès-Chevreuses (take the underpass to platform 1).

Train timetables: check the Transilien website.

For motorists:
Park in the car park of one of the stations you pass along the way: Orsay-Ville (S/E) (limited capacity); Le Guichet (2); Lozère, near (5).

Good walking shoes are sufficient for this short route, which follows well-maintained paths or tarmac roads.

Bar, restaurant and mini-market near Le Guichet station (2). Picnic tables at the former Troche quarry, a short distance further on (3).

A detailed map is useful (at the very least the one accompanying this description).

Walk completed by the author on 27 February 2022.

- A pleasant walk along the Yvette.
- A few panoramic views at the top of the steps between (2) and (4).
- Lac du Mail, near (1).
- Rock boulders from the former La Troche sandstone quarry, shortly after (4).
- Lac de Lozère, before (6).