The falun rock formation that surrounds you began 10 millions years ago.
Following global warming, the water level went up and the ocean invaded most of the northwestern France giving rise to the Sea of Falun. The valley of the Layon, where Doue La Fontaine is located, was covered by 25 meters of sea water. Thus, sediment shellfish and remains of marine and terrestrial animals stacked up with the tidal rhythms. Layers of falun were then formed up to 23 meters thick.
At the time, the region was in a subtropical climate zone where a specific flora and fauna existed, comparable to the current coast of Senegal. (sea of Falun visual material)
The sand left by the sea is more or less solidified depending on the percentage of calcium-carbonate contained in the shells which had dissolved and cemented all the grains.
At Les Perrieres, the falun deposited with the ebb and flow of the tides which was strong enough to move underwater dunes. This is why you can observe oblique strata on the rocksides corresponding to the displacement of these dunes. ( « dent de requin » + « Région douessine 10 millions d’années » visual materials