Le Maar de Borée-Echamps
Ardèche ()
The vaporisation of the water in the confined space of the feeder chimney causes an overpressure and an explosion that pulverises the rocks in the conduit and the juvenile magma (fresh magma in the process of rising). The more or less coarse debris is violently thrown outwards where it settles to form a ring of tuffs. The maar was probably formed very recently (a few hundred thousand years at most), which links it to the volcanism of the Bas Vivarais, like the maar at Saint Martial.
The overflow of the lava lake from Echamps fed a flow of which a few shreds can be found in the Azette valley, at Bois Lantal, Chanéac....
After a calm phase, the activity ended with a brief strombolian episode (alternating projections and flows) that produced several small cones around the maar (Rastillas and the cone supported by the Pialox phonolite, which emitted a small flow towards the Gazeille).
Explosive materials: granitic rocks, prodotites, ashes, granules, magma blocks, small cauliflower bombs, slag, pozzolan, etc.
All year round.
TarifsFree access.
Contact et accès 07310 BoréeArdèche (7)
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