Durbuy anticline

Near the Durbuy anticline, look for a black slate layer. This is the result of one of the greatest ecological disasters on Earth. You're looking here at a limestone layer that was deposited in "healthy times" but "massive doom was on the way."

Some context about that ecological disaster (known as the Kelkwasser Event) and what caused it.

What caused the Kellwasser event's ecological disaster?

1. Because land plants proliferated during this period and their roots loosened deeper soils, nutrients such as nitrogen and phosphorus were transported to the sea via rivers. This phenomenon was exacerbated by a major mountain building event caused by the collision between Laurussia and Gondwana (the Variscan orogeny , also known as the Hercynian orogeny ). There was also increased volcanic activity in Siberia, which likely also impacted global climate change and oxygen-poor (anoxic) seas. Call it the geological version of "a problem never comes alone."
2. This leads to eutrophication : an explosive growth of algae in the sea that was there at that time.
3. This explosive algae growth led to a reduction in light, oxygen, and the depletion of certain minerals. Consequently, they destroyed their own ecosystem through explosive growth .
4. The algae die en masse and their dead biomass is then broken down by bacteria, which uses up the remaining oxygen in the water and creates anoxic (oxygen-free) conditions .
5. This made the sea completely uninhabitable, even for other organisms, which died en masse. The extinction can be recognized as black clay layers (black shales) in this deposit.

This was a dramatic event on Earth in which about 70-80% of all species became extinct, especially marine organisms such as corals, stromatophores, ammonites and brachiopods.

The limestones occurring in the Durbuy anticline are part of the Moulin Liénaux/Philippeville Formation, deposits from the Frasnian of the Devonian. In the Ardennes, including the Durbuy area, traces of the Kellwasser Event can also be found, mainly as dark shale layers (such as those of the Matagne Formation).

Pascal Brackman