2.1.10 Ville - Pommeroeul Chert Formation - VPO

Authors: Robaszynski (1975c).

Description: Light-coloured, chalky, siliceous limestone, rarely marly, with numerous, more or less completelysilicifiedconcretions. Towards the top there is a progressive transition into black cherts of the Hautrage Formation. Fauna is extremely rare.

Stratotype: Motorway cutting, at the bridge connecting Ville-Pommeroeul and Rond du Bois-de-Ville (see Robaszynski, 1975b, p. 35).

Area: MonsBasin. In the eastern part of the basin, the Formation also contains glauconite, and becomes a "glauconitite" with siliceous nodules of up to 10 cm in size; when altered they have a powdery aspect: Also known as the "Verts à têtes-de-chat" auct. (see J. Cornet, 1923) or the "Glauconitite de Thieu" (see Robaszynski, 1975c).

Thickness: 4 to 30 m.

Age: Late Turonian on the basis of Micraster leskei, recorded from Harchies.

Remarks: - This formation is also known as the "Fortes-Toises" auct. (J. Cornet, 1923).

- The designation "Formation de Merlin" (Doremus, 1997) is a junior synonym of the Ville-Pommeroeul Chert Formation.