In the Lower Cretaceous period, the entire subalpine area was subject to intense tectonic activity. The Durance Fault-Line separates the Dauphiné lower lying basin area to the west from a higher area to the east.
This area is subject to strong erosion and is criss-crossed by east-west underground channels of waterways.

The currents transport coarse and fine sediments from the erosion of the slopes.
When the speed of the water decreases, the coarse and fine sediments are deposited, giving rise to the creation of breaches and thus the creations of chasms.
Today, with the uprising of the Alps and the subseqent effects of erosion, we can now discover this site.

This imposing mass of rock is poetically nicknamed The Whale.
We can also observe phenomena testifying to the activity of underwater channels dating from the same period in the Bès valley (in the county, Alpes de Haute-Provence) and in the Ceüse mountain range (in the neighbouring county, Hautes-Alpes).