Before entering Étrépilly, coming from the west, after passing Brunoy, park at the three-way junction on the right, by the iron cross (GPS 49.036562, 2.925309).
(S/E) Follow the road towards the village. Take the grassy/dirt track on the right, running alongside the marshes, to Rue du Pont des Planches.
(1) Just before reaching the street, turn right onto the grassy path that climbs towards the plain.
(2) Take the first grassy track on the right, on the La Fâche plot.
(3) Turn right onto the road. Continue along the road, passing between the Fontaine Saint-Laurent and the highest point of the plateau (116 m), then head back down to the car park (S/E), either via the small road or the grassy track running alongside it.