Le Dérochoir from Plaine-Joux
Summer hike
Le Dérochoir from Plaine-Joux

Le Dérochoir from Plaine-Joux

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An aerial hike with difficult and vertiginous passages and a via ferrata touch . This itinerary with technical difficulties is reserved for very experienced hikers.
You will end your hike by climbing and descending the Passage du Dérochoir. Progress in this immense scree, at the beginning on a path, then in a chaos of rocks. On some passages you will need to climb the slabs. Chains, ropes or steps help you while climbing. But be aware that this is a difficult and dizzying trail, reserved for experienced hikers.
The arrival on the Desert de Platé by the Passage du Dérochoir is amazing. The view is breathtaking; the green colors of Vallée de l’Arve and Mont-Blanc on one side, and a mineral landscape on the other.

15 points of interest

View on Le Dérochoir

Le Dérochoir is the result of successive landslides. The first known and documented dates back to 1471. The second and last, at least for the moment, occurred in 1751. At the foot of the cliff stands a huge landslide cone which forms an unstable slope.
These various landslides created a passage making it possible to cross the Fiz ridge.
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The mont Blanc before mountaineering

Many mountaineers dream of climbing mont Blanc, the highest peak in Western Europe. But it has not always been that popular. In the past, the inhabitants of mountain villages were scared of the mountains environment which led to numerous superstitions, as you can tell from the names given to the summits (“Mont Maudit”, meaning Damned mountain, Aiguilles du Diable, meaning Devil peaks, etc.). Only shepherds, chamois hunters and crystal miners (mining rock crystals) frequented these hostile environments. The first ascents were made by daring "outsiders" who employed these mountain experts as guides.
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The Hazel Grouse

It is the smallest and most discreet of the mountain Galliformes species.
It is much less known than the Black Grouse or the Rock Ptarmigan because it lives exclusively in the forest!
But it is as important as the others from a biological and scientific point of view: it is an indicator species of environmental changes. Its specific demands in terms of vegetation and diversity of tree species ask for an adapted forest management. Bad preservation management of this habitats is one of the main causes of regression of the species.
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The Mountain Ash

It is a small tree growing in forest edges. Its fruits are red orange berries loved by thrushes and blackbirds.
The fruits can be used to make to make brandy, jelly or jam. But be aware that they are toxic at maturity, so you have to pick them earlier!
In the nature reserve, the Mountain Ash is part of a participatory science program intended to measure the impact of climate change on the ecosystems of the mountain.
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The 'Ayères'

Originally, the word "Ahier" comes from a roman patois meaning Sycamore Maple. The words "pierrières" and "roc" are references to the numerous boulders, evidence of the landslides of Dérochoir, including the one in 1751 which killed 6 people and a few domestic animals. All these cabins were alpine cabins for agricultural use. They are now used as holiday cottages.
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The alpine cabin

The alpine cabine is a small building which, gattered with others, forms a small hamlet. These constructions were originally intended for the organization of agricultural life in the mountains. These cabins were used in the summer to shelter the shepherds and their family. They were also used for milking and the production of cheese and other dairy products.
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The Wallcreeper

This bird is closely linked to the steepest rock walls! It lives mainly in the mountains, from the Alps to the Himalayas. But during a cold and snowy winter it can settle in stone buildings in the heart of the cities!

Excellent climber, it is able to catch insects hidden in the most inaccessible rock cracks, thanks to a long curved beak and clawed toes.

It is difficult to observe, except when flying in undulating waves reminding of butterflies, showing its shimmering colors of grey, black and red!
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The mountain refuge of Châtelet d'Ayères

A bucolic landscape with a view of Mont-Blanc, that’s where is settled the pretty refuge of Châtelet d'Ayères.

Built 100 years ago and currently runned by a family from Passy, it has welcomed some famous mountaineers in the 1950s: Roger Frison-Roche, Maurice Herzog...

Its renowned cuisine is loved by gourmets looking for delightful blueberry pies or the famous “farcement”, a very famous local dish.

The refuge is powered by solar energy. To be consumed with moderation!
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Odonates, more commonly known as dragonflies, are insects.
There are two stages in their lifecycle: a "larva" (or nymph) stage which is aquatic followed by a terrestrial stage, when the adults are grown to adults.
Dragonflies are predators: they are carnivores that feed on different types of prey depending on their stage. They eat other insects as well.
Their distribution is strongly linked to climate conditions and any change has a strong impact on their presence. Destruction of their wetland habitats is one of the main threats to dragonflies.
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The Grass Snake

Semi-aquatic, it mainly frequents wetlands but also drier environments hosting its main prey, such as amphibians (frogs, toads, salamanders or newts).
It's a protected species, like all reptiles!
It can be identified by its round pupils, its olive grey color and its double black and white or yellow collar shaped pattern. Or by another special feature: when it feels in danger, it spits out a foul smelling liquid and pretends to be dead, revealing its two-colored piano pattern on its ventral surface!
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Lac Vert

This amazingly colored lake was probably formed by the landslide of the Dérochoir rock (Fiz ridge to the north) in 1471.
There are several explanations for its emerald green color, including the surrounding vegetation consisting mostly of spruces, which are reflected in its waters. But the presence of blue algae or cyanophyceae in the lake is also a probable cause.
The water comes from sources providing the lake by its surface and underground.
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The history of Plaine-Joux

From forest to mountain pasture, Plaine-Joux has not always been a ski resort as reflected in its name, which would mean "forest on a flat space".

As early as the 1930’s, the inhabitants of Passy were already practicing ski activities in this location enjoying a magnificent panorama. It was around 1965 that it officially became a communal ski resort. Even nowadays, Plaine-Joux remains, as well in summer as in winter, a popular family resort for skiing, hiking, paragliding... and contemplation.
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The mont Blanc

Beneath the snow and the glaciers, two main rock types form the Mont-Blanc Massif: the sharp edges and the highest peaks are made of very hard granite (from the left to the right: Aiguilles de Chamonix including Aiguille du Midi, Mont Blanc du Tacul, Mont Maudit, summit of mont Blanc) while the rounder - because softer - parts are in gneiss (from the left to the right: Dôme du Goûter, Aiguille du Goûter, Aiguille de Bionnassay,...).

These two so-called crystalline rocks come from the core of the Earth in fusion.
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The placid Ibex

The Ibex is not very shy, especially compared to the Chamois sharing its territory.
Unlike most other mountain species, it remains at altitude even when winter and snow arrive.
It then reaches ridges and snow-cleared areas where it will more easily find grass to feed on. This search for food costs a lot of energy. So, if you see it, do not approach and let it leave quietly in order to avoid wasting its precious energy, especially in winter.
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La Maison de la Réserve

The exhibition an information office Maison de la Réserve naturelle de Passy is located in Plaine-Joux and welcomes you during the school holidays. The permanent exhibition about fauna, flora and landscapes will open the doors to the nature reserve. You may find answers to some of your questions here and can admire the wild species hidden in nature. If the Maison de la Réserve naturelle is closed, don’t worry, go up to the passageway. There is permanent free access to information about former (geological times) and present landscapes, the wonders of biodiversity and the great challenges of the mountains of the future (water, glaciers, global warming...).
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Departure from Maison de la Réserve naturelle de Passy.
  1. Take the paved road which passes in front of the restaurant "Lou Pacheran".
  2. Take the track that climbs towards the Col d'Anterne. Beacon 102.
  3. At the orientation table, continue on the track towards the Col d'Anterne. Beacon 103.
  4. Continue on the track towards Ayères des Pierrières, Col d'Anterne. Beacon 16.
  5. Cross the hamlet of Ayères des Pierrières.
  6. Beacon 18. Take the path on the left, and follow the direction Le Dérochoir. Difficult trail. Marked by red dots on the rocks.
  7. At the passage Le Dérochoir, take the opposite path.
  8. Beacon 18. Head towards Plaine Joux and cross the hamlet of Ayères des Pierrières.
  9. Beacon 16. Turn left towards Les Mollays.
  10. At the Châtelet refuge. Take the direction of Lac Vert - Plaine Joux. Beacon 143.
  11. Take the track that goes down to the left. Direction Lac Vert - Plaine Joux. Beacon 95.
  12. Cross the car park Lac Vert and take the paved road towards Plaine Joux. Beacon 159.
  13. Beacon 93. Take the path on the left towards Plaine Joux.
  14. Turn left on the paved road. Direction Plaine Joux.
Departure : Maison de la Réserve naturelle de Passy
Arrival : Maison de la Réserve naturelle de Passy
Towns crossed : Passy, Sixt-Fer-à-Cheval

Altimetric profile

Sensitive areas

Along your trek, you will go through sensitive areas related to the presence of a specific species or environment. In these areas, an appropriate behaviour allows to contribute to their preservation. For detailed information, specific forms are accessible for each area.
Impacted practices:
Aerial, , Land, Vertical
Asters - Conservatoire d'espaces naturels de Haute Savoie
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Impacted practices:
Aerial, , Land, Vertical
Sensitivity periods:
Asters - Conservatoire d'espaces naturels de Haute Savoie
Christelle BAKHACHE : 06 49 99 99 48


This itinerary runs through a nature reserve, please consult the regulations.

Difficult and aerial passage, for experienced hikers.

Take water with you.


Bus SAT Mont-Blanc L85

Access and parking

Reach the Passy Plaine-Joux resort by road D43.
Parking at the entrance of the station. Bus line L85 (SAT Mont-Blanc).

Report a problem or an error

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