Derborence

Two enormous rockfalls came off the Diablerets massif in 1714 and 1749, burying alp pastures and the people on them and damming the valley - the lake behind that debris is Derborence. The scale of the collapse is still obvious in the boulder field. What makes the site scientifically important is what grew back and what never was cut: the forest here includes stands of spruce and larch that have never been logged, one of the few genuinely primeval woodland remnants in the Alps, protected as a reserve since 1959. Charles Ferdinand Ramuz set his novel Derborence on the 1714 disaster, which is how most Swiss know the name. The road in is single-lane with unlit tunnels.

What you actually see

• A lake dammed by rockfall - the debris of 1714 and 1749.
• Untouched forest - never-logged spruce and larch, a reserve since 1959.
• The boulder field - the raw scale of the collapse still visible.
• Ramuz's setting - the novel that made the disaster known.

When to go

Late June to October. Half a day.

Honest expectations

The access road is narrow, exposed and has unlit tunnels - not for nervous drivers, and it closes for winter. Facilities are one inn. Do not walk into the reserve off the marked paths. Rockfall risk means some areas are signed off.

Nearby

Conthey and the Rhone valley are below; Anzere is east on the terrace.