La Tour Percee

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Raiders of the lost arch

At the end of May 2005 Grenoble climber Pascal Sombardier was exploring the foot of the Grand Manti cliffs situated in the Chartreuse mountains between Grenoble and Chambery He spied a couloir and decided to explore further. After climbing a short step he found himself in a suspended cwm, turning to his right he had trouble believing what he saw, a giant double arch spanning some 32 meters. An expert on the region, he had never heard of this natural wonder.

La Tour Percée

La Tour Percée

Back in the valley he showed the photograph to walkers and climbers. It must be fake, there was no way that such a span could have remained hidden from view. He contacted the The Natural Arch and Bridge Society (NABS), a non-profit society that supports the study, appreciation, and preservation of natural arches and bridges. Their Europe expert rushed to view the marvel and told Pascal it is the biggest span in the Alps and the double arch is probably unique in the world.

la tour percee

The lower arch spans 32 meters

How had such an arch remained hidden for so long? There are no paths leading to base of the cliffs and access from above requires a long and precarious traverse with several abseils. The arch lies entirely within a bowl. From below it is completely invisible as is the access couloir. The arch can be seen from above but appears to be a hollow, one of many in the surrounding cliffs. An observer flying by in a plane or helicopter would see a tower but not the openings. Climbers, the only people who would have the technical expertise to explore the area, never ventured beyond the vast yellow 400 meter rock face of the Grand Manti.

double hole

Double holes behind the arch

The arch lies on private land belonging to Bruno de Quinsonas who also owns the Chateau of Le Touvet. It let out to hunters. Access, while not strictly forbidden, is not exactly encouraged either. There is a barrier and a sign warning that people venturing onto the estate are at risk. Any form of mechanized access on the forest trails, such as with a mountain bike, is banned. It is possible that hunters or forest guards had already visited the site as the lush grass is a favourite grazing spot for Chamois. There was no evidence of visits… tracks, cartridges or other human detritus and no-one from the area had heard of the arch.


Couloir to the lost arch

The exact location of the arch has been a closely guarded secret since its discovery. Pascal Sombardier’s book Chartreuse Inedit, Itineraires Insolites (Secret Chartreuse, Weird Walks) has some super photos but declines to give a detailed route leaving it up the reader. There were some clues, the access couloir was somewhere in a 1000 meter stretch from a large needle shaped rock called the Aiguillette and the abrupt face of the Grand Manti. I also had a grainy photo of the couloir taken during the winter by a ski mountaineer. We knew that the couloir didn’t require any particular climbing skills and was sheer on the right bank, rocky on the left. I had scanned the area from the col de Marcieu with powerful binoculars but nothing was visible, not even the access couloir. It all looked like an impenetrable barrier.

la tour percee from col marcieu

The Tour from le Col du Marcieu

With the dark side of the moon mapped and explorers crawling over every inch of the Himalayas it is hard to believe that there are new wonders to discover and places never trodden by man within half an hour of a major European town.


Tower with the Belledonne behind

Mountain RangeChartreuse
SummitPas de Ragris
Altitude1817 meters
Distance5.2km to the Pas de Ragris
MapsIGN TOP 25 3334 OT Chartreuse Sud
GPS WaypointN 45.3690°, E 05.9043° - 1731 m
GPS RouteGoogle-Earth:Chartreuse
MarkingsNone - one or two cairns, orange in the Pas de Ragris
Equipment40 meter rope, '8', climbing harness and hat, loops
Road AccessA41 Crolles exit -> N90 to la Terrace -> D30 -> D30c to le Col du Marcieu
Starting Altitude1060m
Ascent1140 meters
Time4.5 hours to the Pas de Ragris?
Guide BooksAmazon-FR:2723453960
WebsiteLa Tour Percée
Authordavidof - 14th July 2006

Some short scrambles

The route does not require any particular climbing skills. You could tackle it without any equipment. However you should not confuse difficulty with danger. The steep slopes are slippery when humid, especially the couloir climbed to reach the upper loop. Any fall would probably result in death. There is also the risk of stone fall from above. The number of stones at the base of cliffs are a testament to the dangers. A climbing hat is really obligatory from the moment you reach the base of the cliffs to the Pas de Ragris. Be careful about dislodging stones into the couloirs as people may be climbing below. French law states that the people upslope are responsible for stone fall. Take particular care when abseiling. The upper loop has a well trodden path which overlooks steep cliffs but is not particuarly exposed. The Aup du Seuil can be climbed using fixed ropes (GPS N 45.3649°, E 05.9036° 1865m) and there are fixed ropes on the loop (N 45.3631°, E 05.9024°) over an exposed section above l'Aiguilette. Do not leave any litter in this still pristine environment.


la tour percee

La Tour Percée from the loop

So on Bastille Day, 2006 we set off into the unknown. We knew that the arch was visible from the Aup du Seuil so we decided to climb through the steep woodland above the Col de Marcieu ski resort to exit below the cliffs somewhere in the middle of the zone to be searched. Rain had been torrential during the night and the approach was muddy and difficult, especially for Ben who was carrying a 70 meter length of rope. Coming out of the forest I almost came face to face with a grazing chamois who set off up the cliffs with an athletic grace that would put star climbers to shame. It was just after 6am and the sun was just peeking its head above the sparkling glaciers of le Mont Blanc. The cliffs were bathed in a deep orange glow.

Mont Blanc

Mont Blanc through the lower arch

Above us we were surprised at the number of couloirs snaking up through the rocks. None of them visible from below. However they all required a climb to access. We decided to track back to the Pas de Ragris on a trail left by the chamois. Rounding a nose of rock we stumbled on a couloir that looked suspiciously like our photograph, minus the snow. There also seemed to be tracks. The couloir is around 35 degrees except for a steep section below a 10 meter cliff. This is an ice fall in winter and had caused from problems for the skiers last winter. We found a few footholds off to the right and scrambled up into the cirque. The double arch was immediately visible and didn’t disappoint. We were possibly the first non-French people to set eyes on the miracle. The bowl is covered in grass made slippery by the morning dew. With the 10 meter cliff in the forefront of our thoughts we gingerly scrabbled up to the arch.

upper loop

Ben on the upper loop, the tour is to the right

The upper section was easy to access, it is about a 1.5 meter gap, not enough to stand up. A path lead through to the couloir on the other side. We had seen the base of this earlier on. The slope was fearsomely steep in the wet conditions and we didn’t move off the flat ground but we had enough room to take a photograph. A belay point had been fixed in the couloir. We didn’t understand the purpose but it appears this was used to give a better perspective on the arch for photographs.


A short climb up an exposed couloir

We took GPS reading then climbed onto the roof of the arch via a short series of rocky steeps. We wondered if the couloir where we had seen the belay point could be climbed from this higher vantage. We could see a higher loop (sangle) of grass and thought this might exit onto the Aup de Seuil plateau. After an exposed traversed it was obvious that the couloir had not been equipped, we would need Friends and other climbing paraphernalia to shimmy up a series of difficult chimneys. Ben was downcast and suggested we go down. He is a good climber but has been suffering from tendonitis in his elbows – an extreme golf injury. I decided to explore another chimney, this had good hand holds and exited into a bowl. It seemed possible to traverse some way to the left. Exploring the traverse revealed another couloir, a humid 50 degree slope of mud and grass but this lead to the upper loop. I called to Ben whose climbers eyes immediately spotted something I had missed, a belay point and a little red paint arrow. We were on the right tracks it would seem.

belay point

Belay Point

We finally got to use Ben’s rope. I belayed from below as Ben tackled the couloir. Without a rope it is extremely exposed as it is the continuation of the couloir we had climbed to reach the arch. A fall would take the unlucky victim several hundred meters over rocks and certain death. The upper loop didn’t immediately exit onto the ridge above, instead it climbed along the base of the cliffs. It didn’t look that promising but looks were deceptive. The track lead into another bowl and on the far side we came across some fixed ropes leading to the radio relay of the Aup du Seuil and more bizarrely, a standard French letter box. The loop was enchanting and we decided to see where it would take us. The next bowl was above the Aiguillette with its strange troglodyte grottos in the surrounding cliffs. The exit was tricky but we clipped onto some fixed ropes. These has presumably been installed by Pascal to secure the route and are somewhat controversial. Some believe they will encourage inexperienced walkers onto the dangerous cliffs. The final stretch lead down to the Pas de Ragris. Over six hours we had not seen a single soul and it was a shock to suddenly be thrust into the comings and goings of holiday walkers. We felt extremely privileged to have witnessed this natural wonder. What will the future bring? Restrictions if the route proves too popular? Maybe classification as a Unesco World Heritage Site? Sure Pascal Sombardier deserves some recognition for his exploration of this “inner space”?


Troglodyte village?

Contributed by davidof on the 14th July, 2006

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