3.2.7 Colibeau Formation - CLB

Authors: Maillieux, 1930a; emend. Michot, 1954.

Description: Dark grey or brownish black coarse-grained shale with rare intercalations of clayey sandstone, quartz- rich and rather strongly micaceous (Maillieux, 1930a; Martin, 1969a).

Stratotype: railway section along railway Namur-Arlon, at locality Colibeau, near Naninne (Martin, 1969).

Area: Condroz inlier.

Thickness: ± 650 m (Michot, 1957).

Age: Brachiopod fauna in the upper part of the unit, with Spirifer elevatus, Plethorhyncha percostata and Stropheodonta simulans, one specimen of each, similar to the Whitcliffe Flags in Wales, U.K. (Malaise, 1913; Maillieux, 1930a): Ludfordian (late Ludlow) age.

(J. VERNIERS)