This maar is a superb example of phreatomagmatic volcanic activity. The operation is characterized by an intense explosive activity caused by the meeting of the hot magma during the ascent with the waters infiltrated from the surface.
Description
With the highest average flow of the entire department of Ardèche (about 80l/s), the springs of Molines constitute a certain potential wealth for Boutières both from a tourist and economic point of view. Their existence is closely linked to that of the Borée-Echamps Volcano. This indeed corresponds to a maar, an explosion crater linked to the meeting between water and magma during the ascent. The various rocks pulverized during the explosions form a heterogeneous sandy material which accumulated to a great thickness in the crater before being covered and protected by a lake of lava which appeared at the end of the volcanic activity and whose solidification on the spot led to the formation of the plain of Echamp.
The rainwater collected by this plain infiltrates through the cracks in this basalt pancake and is stored in the interstices of the underlying sandy accumulation which plays the role of a sponge in a way. This constitutes both an important reservoir of water guaranteeing the regularity of the flow of the springs and a filter all the better as the water has been able to stay there for a long time before emerging on the side of the slope.
In the case of the Molines springs, this course of water through the reservoir is probably a few years. Their exit point corresponds to a breach opened in this reservoir due to the retreat of the slope by erosion.
Opening
From 01 / 01 to 31 / 12.
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These are typical examples of viscous lava needles that have moved into place almost in a solid state. Here no craters but massive shapes in the landscape. Interpretation table between the two rocks.
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