Mont Gerbier de Jonc

The Gerbier de Jonc is a phonolite dome, a plug of viscous lava that never flowed far, rising to about one thousand five hundred and fifty-one metres with sides of loose broken slabs that ring when struck. At its foot the Loire begins: three separate sources are claimed, one of them running through a farmhouse, and the longest river in France, over one thousand kilometres, starts here as water you could step over. The path to the summit is short but steep on loose rock. The surrounding Ardeche plateau is high, open and cold, dotted with more volcanic domes and used for summer grazing.

What you actually see

• The volcanic dome - a steep cone of ringing phonolite slabs.
• The Loire sources - the first trickles of France's longest river.
• The plateau - high open grazing land studded with other domes.
• The summit view - the Ardeche and Velay uplands from the top.

When to go

May to October; the plateau is snowbound and windswept in winter and roads can close. The climb takes about forty minutes and is slippery in wet weather.

Honest expectations

The path is loose rock and has been closed at times for erosion repair; check before climbing. The source itself is unspectacular, a trickle beside a souvenir shop. Weather on the plateau turns quickly.

Nearby

Le Puy-en-Velay lies northwest; the Ardeche gorges are southeast.