The limestone outcrops of the cliffs on the other side of the Reynier river were deposited on the sea bed about 140 million years ago during the Kimmeridgian period.

The geometry of the Kimmeridgian limestone-layers illustrates the instability of the seabed at the end of the Jurassic period. Indeed, we can observe geologically folded, contorted and fragmented layers between two more regular sets of layers. This type of geological feature, called "a slump", indicates the typically sliding of banks of sediment that are still soft and pliable and not yet entirely transformed into solid rock. This suggests the existence of slopes and therefore of an underwater terrain at that time.

Several levels of "slumps" can be observed superimposed in the cliff section, which shows the repetition of the phenomenon over time.

The study of various sites throughout South East France has enabled us to reconstruct this paleogeography, (paleogeography is the study of geographical features at periods in the geological past).

When this disturbance and rearrangement of the sediment is pushed to the extreme, we end up with complete disintegration and the formation of a so-called intraformational breccia rock formation.