Gour
Definition of gour :
- Hole of water in the rock, generally keeping water in period dries (see also Marmite of the visible devil
- Concrétion in some Grotte S
Gour as a concretion
The gours result from calcite deposits. The subterranean water dissolves the limestone (more precisely the calcium carbonate) of under ground. This water can evaporate when it is brought to stagnate in a preexistent cavity: it makes " flaques" of water.
The concentration in Calcite increases and this one settles with the accesses of the " flaque" by increasing the level of water. The water supply must be sufficiently weak or discontinuous not to decrease this concentration and to stop the phénomêne concretion.
The result is a basin called " gour". They are often laid out the ones following the others; lower gours taking delivery of the too full one with the gours downstream (cf photograph)
Thousand-year-old erosion finishes by miter the calcareous base by opening unsoundable gouffes, such those which one knows in Vercors or in Ardeche.
Sites
- France Country of the caves
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