Pierre Du Serpent

BurtignySwitzerland 46° N · 6° E Verified Aug 2026

A glacial erratic in the Jura forest whose 'serpent' mark is natural erosion, not legend. It survived because it was too remote to quarry for building stone.

View map
Time needed
30 min (stone only); 3.5 hrs full loop
Entry
Free
Access
Forest path, not wheelchair accessible
Best season
Spring–Autumn

The most unremarkable stone in a Swiss forest is also a refugee from the Alps. Pierre du Serpent, tucked at the edge of the Bois des Tattes above Burtigny in Vaud, Switzerland, is a glacial erratic — a fragment of Alpine granite that the Rhône glacier set down here around 20,000 years ago. You visit not to see a monument, but to stand next to evidence of how far ice can carry a mountain.

The stone is small enough to miss. From the forest edge, take the little path behind the picnic table; the block sits roughly twenty metres in, unassuming. Look closely and you may find what earlier observers swore were a human footprint and a serpent's trace. The on-site panel records a less romantic verdict: the shapes are probably the work of erosion and time.

That shift — from mythical serpent to natural scar — echoes a larger scientific fight. For much of the nineteenth century, folk explanations clung to such boulders. Then geologists, most publicly Louis Agassiz, argued that ice had done the transporting. Pierre du Serpent stopped looking like magic and started looking like machinery.

Most of its cousins vanished into Vaud's villages. Hard Alpine granite was valuable stuff — too valuable to leave lying around — and accessible blocks were quarried for foundations, doorsteps and stair steps. This one survived because it was too far into the trees to bother with. Boring, in other words, became its best defence.

Researched by the Audiala editorial team from historical records, architectural archives, and local expertise.

What to see

  1. Pierre du Serpent

    Half-buried at the edge of the Bois des Tattes, this Alpine granite block rode a glacier here about 20,000 years ago and never left. Most of its siblings became doorsteps and house foundations in nearby villages; this one survived because it sits far enough into the forest to escape the builders. Run your fingers through it. Early observers read the groove as a serpent — after rain the granite darkens to grey-blue and the mark sharpens, even if the panel beside it says natural erosion carved the shape.

  2. Le plus grand sapin de la forêt

    A short climb from the stone, the path comes to a fir that hikers on AllTrails call the largest in the Bois des Tattes. No plaque gives its height. You measure it with the span of your arms and the resin smell that clings to your coat. The trunk is ridged like a mountain range in miniature. On quiet mornings the only sound is wind moving through needles, interrupted by a cowbell from the pastures below.

  3. Sentier des Pierres loop

    The full 4.7 km loop climbs just 120 m as it threads five glacial erratics through the Bois des Tattes, marked by yellow diamond signposts from Burtigny. No ticket booth, no café. Just packed earth, gravel and occasional panels explaining how the boulders got here. Forest clearings break open toward Lake Geneva and the Alps, so the route alternates between cool shade and sudden horizon. Go in autumn, when beech leaves pile like gold coins underfoot and the stones half-emerge from mist.

Plan your visit

Getting There
Drive to Burtigny, then follow Route des Matagasses to Route du Molard and turn left at the farm 'Sur la Motte'. Park at the forest edge above the picnic table; the stone sits about 20 metres down a small path. No direct bus reaches the boulder, so check SBB/CFF for the nearest connection to Burtigny.
Opening Hours
No gates, ticket booth, or closing time. This forest-edge erratic is open 24/7, year-round. As of 2026, no seasonal closures are posted, but December–February snow or ice can make the last path section slippery.
Time Needed
Stone only: 15–30 minutes from the forest-edge parking, enough to read the info panel and trace the eroded 'serpent' mark. The full 4 km Sentier des Pierres loop takes 1h30 to 2h; the longer 7.4-mile AllTrails variant needs 3–3.5 hours.
Accessibility
Not wheelchair accessible. The boulder sits beyond unpaved forest paths with roots and uneven soil; there are no paved lanes, lifts, or adapted toilets. The full loop gains about 80 m over 4 km, so it is easy on paper but not barrier-free.
Cost & Tickets
Free entry every day—no tickets, no booking, no queues. Parking at the forest-edge trailhead is also free. Combine it with the free Sentier des Pierres route and your only expense is a meal in the village.

History

A Refugee from the Ice Age

Most tourist histories open with a foundation date. Pierre du Serpent has none, because it was never built. It was dropped.

That happened about 20,000 years ago, when the Rhône glacier reached roughly 1,000 metres along the Jura chain and stretched toward Lyon. As the ice thinned, it let go of this Alpine granite block and left it at the edge of what is now the Bois des Tattes.

The turning point

The Scientist Who Never Stood Here

Louis Agassiz (1807–1873) does not appear in the local record for this exact stone. He doesn't need to. The Swiss naturalist and Neuchâtel professor was among the most public champions of the idea that vast ice sheets had once smothered Switzerland, and erratic boulders like this one were the physical proof he pointed to.

What was at stake for Agassiz was his reputation. In the late 1830s, the notion of a continent-wide Ice Age sounded absurd to many geologists; accepting it meant rewriting the planet's recent past. His turning point came as evidence accumulated — the Jura's scattered Alpine fragments stopped looking like folk curiosities and started looking like a delivery system.

Burtigny's own trail literature records that glacial theory only imposed itself in the mid-19th century. So a visitor at Pierre du Serpent is standing on the winning side of a fight that once seemed almost impossible to win.

The Serpent That Isn't a Serpent

The stone takes its name from a trace that looks like a snake. The on-site panel puts it plainly: the shape, along with a human-footprint-shaped mark, is natural — carved by erosion and time, not by reptile or hand. Some unnamed authors once believed otherwise, but their identities have not survived. Most people arrive searching for the serpent and overlook the footprint altogether.

Saved by Being Forgotten

The same qualities that made Alpine granite precious for Vaud's villages nearly did for Pierre du Serpent. Hard and frost-resistant, the boulders were cut up for foundations, retaining walls, doorsteps and stair steps. Most accessible erratics disappeared this way. This one survived because it sat in a remote forest corner, too inconvenient to cart away. Its obscurity became its protection.

Tips for visitors

  • Do all four stones

    Pierre du Serpent is small, so make the 4 km Sentier des Pierres loop the actual outing. It links this boulder with Pierre à Roland, Pierre à Mille Trous, and Pierre à Phébou.

  • Perch Mondays at Lion d'Or

    Auberge du Lion d'Or on Place du Tilleul 1 closes Tuesdays and Wednesdays. Come Monday evening for filets de perches à gogo, or order the Gruyère fondue on the terrace.

  • Go March–October

    Best conditions run March through October, when the forest paths stay dry and the leaf canopy is at its best. Early morning or late afternoon side light makes the stone's eroded serpent mark visible.

  • Photograph the erosion groove

    No photo restrictions apply, but the serpent shape reads best in raking light, not at noon. Bring a small torch to illuminate the grooves and footprint-like depressions.

  • Mind the farm gates

    The path from Route du Molard passes farm buildings at Sur la Motte and open pasture. Close any gates behind you and stick to the marked trail.

Frequently asked

Is Pierre du Serpent worth visiting?

Only if you pair it with the Sentier des Pierres loop. By itself the boulder is small and easy to walk past. With the 4 km circuit of erratics and the giant fir, it makes a fine quiet afternoon.

How long do you need at Pierre du Serpent?

Fifteen to thirty minutes if you're only seeing the stone. The full Sentier des Pierres loop runs about 4 km and takes 1h15 to 1h30. That's the better use of your time.

How do I get to Pierre du Serpent from Burtigny?

Drive or walk out of Burtigny on Route des Matagasses, continue onto Route du Molard, then turn left at the farm called Sur la Motte. Park at the forest edge and take the small path behind the picnic table; the stone sits about 20 metres in. No direct public transport to the boulder appears in local sources.

What is the best time to visit Pierre du Serpent?

March to October, with autumn as the standout. After rain, the granite darkens and the serpent groove becomes easier to trace. Snow can hide the mark in winter.

Can you visit Pierre du Serpent for free?

Yes, it's free and always open. There's no ticket office, visitor centre, or gate. You just follow the forest path to the boulder.

What should I not miss at Pierre du Serpent?

The serpent groove on the rock surface, best seen when the granite is wet. Run your fingers over the coarse crystals and look for the fainter footprint-like hollow nearby. If you walk the loop, don't skip the giant fir that hikers point to as the largest in the forest.

What is Pierre du Serpent?

A small glacial erratic boulder of Alpine granite, dropped by the Rhône glacier roughly 20,000 years ago on the Jura slopes above Burtigny. It sits at 807 m at the forest edge. The local panel says the serpent and footprint marks are probably natural erosion, not carvings.

Sources & attribution 8

Researched and written by the Audiala editorial team from historical records, architectural archives, and local expertise. Last reviewed August 2026.

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Photo credits (2)
  1. Pierre à Roland — Marti80 — CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0/) — Source: https://commons.wikimedia.org/wiki/File:Pierre_à_Roland.jpg
  2. Pierre à Phébou — Marti80 — CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0/) — Source: https://commons.wikimedia.org/wiki/File:Pierre_à_Phébou.jpg

Photos may have been resized or cropped.