4.2.2 La Venne Formation - VEN (old: Rv3-4)

Author: after Geukens, 1999.

Description: Heterogeneous unit characterised by the alternation of black slate and dark quartzite. The quartzite is sometimes very clayey and micaceous. In the middle part very thick beds occur of grey-bluish quartzite which can contain thin gravel layers. The lower part is characterised by a rhythmic sedimentation with units consisting of, from base to top, coarse sandstone, fine sandstone, siltstone and slate, and also by well-stratified blue quartzite and by micaceous sandstone beds. Volcanic intrusions are present, mostly acid in composition.

Stratotype: Not yet defined; type area in the Amblève valley, along the railway sections between La Gleize and Coo.

Area: Stavelot Massif.

Thickness: 500 m.

Age: Mid to Late Cambrian based on acritarchs (Vanguestaine & Van Looy, 1983; Ribecai & Vanguestaine, 1993).