Pas De La Branche

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Before widespread road transport routes like the Pas de la Branche were used by travelers to pass directly from one valley to the next. In this case from the commune of St Ismier in the Gresivaudan to Le Sappey in the Chartreuse. On the St Ismier side the route follows the depositions zone of rock avalanches from the cliffs above. The route is a stiff climb and not without danger and should only be undertaken in dry conditions. There is the risk of stone fall on the upper sections.


la Corbonne

There is parking for five cars at the reservoirs. The track to the left is drivable for around 1km. From the reservoir take either the left or right fork (les Combes) direction Pierre Grosse Marie. After about 700 meters (620m.) the two routes rejoin and the path zig-zags up through the woods. At 1km (700m.) there is a T-junction. Take the left fork. The path to the right traverses across the Corbonne torrent to the Pierre Grosse, the whole of this part of the descent can be done on a mountain bike. Note that the IGN map shows a path that continues ahead but this seems to be an error.

Roche Fendue

View into the Gresivaudan valley

The left fork gives some views down the Corbonne torrent and you can see the flood protection work that has been carried out. At 745 m the path turns right past a viewpoint. Here the roche Fendue is visible. At 10h15 on the 15th of July 1979 there was a large landslide as part of the roche Fendue broke away depositing 75,000 m3 of debris below. Stabilization work using grass and shrubs is being carried out on the slopes.


Roche Fendue

At 790m the path traverses the river again. There is an excellent view of the Gresivaudan valley from here. The path gets is less well maintained beyond this point. A sign warns that the Pas de la Branche is closed by decree. The track zig-zags up through the forest. At around 1050 meters a sign on a tree in wood warns of stone fall. The real hostilities begin here. The path is narrow and steep with frequent trees blocking the way although nothing too tricky. The path crosses two scree slopes which should be treated with a great deal of care. Finally at 1180 meters you are confronted with a cliff wall. The path is not evident but traverses to the left (south), crosses a stream bed where there is some cable protection then climbs a 10 meter cliff to the south-west. This is protected by a piece of rope followed by cable on an exposed traverse. The path continues through a wooded glade before turning north with some more cables just before the pas de la Branche. Here it joins the Charteuse north-south ridge path and it is possible to descend directly to le Sappey en Chartreuse through the combe Noire.

pas de la branche interdit

Remember that officially this route is illegal

Mountain RangeChartreuse
SummitPas de la Branche
Altitude1350 meters
MapsIGN TOP 25 3334 OT Chartreuse Sud
GPS WaypointN 45.2614° E 05.7995°
GPS RouteGoogle-Earth:Chartreuse
EquipmentGood hiking boots
Road AccessA41 to St Ismier exit, at pont du Rivet crossroads turn left onto N90 then first right climb to the Corbonne reservoirs
Starting Altitude490m
Ascent860 meters
Time3 hours
Guide Books 
Authordavidof? June 29, 2006, at 04:44


Pas de la Branche

Pas de la Branche

Weather started out sunny but it was snowing when I reached the pass. Not bad for the end of May. This required a rapid descent into the valley. Where the track crosses the Corbonne at point 790 meters (just after the viewpoint) it has been washed away in places and is slippery. Care is needed here and in the cabled section. The cables have been maintained recently. Pascal Sombardier suggests this was done by a local volunteer group.


Cabled section

Contributed by davidof on the 30th May 2006

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