The outcrop in Freyr reveals limestone from the Lower Carboniferous, more specifically from the Tournaisian and Visean (-355 Ma to -325 Ma), both era formerly known as the Dinantien. The underground of Dinant is in that time situated around the equator and covered by a sea. To the north of the seas emerges the ancient Brabant Massif like a shield. Formations are deformed by the Variscan orogeny: Gondwana and (the Caledonian formed) Euramerica will steadily form Pangaea within another 100 million year, being a home for dinosaurs that breaks up again eventually fostering a further growth of biodiversity.

• Dalle école: The Bayard Formation is a dark gray limestone rich in crinoids, occasionally showing black cherts. The formation is visibly stratified. This limestone can be partially or totally dolomitized.

• Tête du Lion and Pape. La Jeunesse and Louis-Philippe: The Waulsort Formation consists of solid unstratified limestone. The carbonated mud shows particles of sponges. At the base there are still crinoids, while at the top fossils are much finer and richer, tending to the Leffe formation.

• Les fissures Georget, Mérinos, Cinq ânes and Al'lègne: The Leffe formation exposes also at the Colébi ravine with lots of black cherts. The formation is composed of a purplish gray limestone that comes in thick patches, with foraminifera fossiles.

• Unclimbable abandoned quarry next to Dalle école: The Molignée formation is the youngest around here and shows gastropods, intraclasts, trilobites,... The reveils a very pronounced syncline (U-shaped layers of rock).

• Source: S. Rekk, X. Legrain, L. Bock and V. Hallet (2016). Patrimoine géologique et pédologique en Province de Namur: 500 millions d’années de façonnement de notre paysage. Itinéraires géologiques et pédologiques. Sentier de Freyr: Contexte géologique.

• Geological map by the government of Wallonia.

• Consult decent geological literature for more information. Don't believe all that a website writes.