La Paroi de Barrachin

The Barrachin rock face was used for backfill, wall construction and the production of aggregates. It boasts a beautiful outcrop that allows the history of the Domaine Briançonnais to be reconstructed in the Triassic period (around 230 million years ago and in the Jurassic period). On the paroi de Barrachin, the first feature is carbonate sedimentary rock with alternating dark limestone and light dolomite beds. This sequence is repeated several times. Next, you can see sedimentary features on the wall: bioturbations due to crustacean burrows, tempestites, "bird eyes", not to mention fossils of stromatolites and dasycladaceae. These sedimentary figures and fossils are proof of the shallowness of the water. Fossils of blue-green algae, which need light for photosynthesis, indicate shallow water (pools 20-30 m deep). Fossils have allowed us to date certain terrains: they were deposited in the Triassic period. At that time, the sea was very shallow. Finally, there are visible deformations; almost at the top we can see two normal faults, the deformation is brittle and took place on the surface, contemporary with the sedimentation. A seismite towers over them. But here, the deformation is flexible. Indeed, it touched the sludge during induration, shaken by an earthquake due to the activity of normal faults at the time.

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