5.10 Orient Formation - ORI
Authors: de Dorlodot, 1909; Camerman, 1944; Mortelmans, 1969; Hennebert & Doremus, 1997a, 1997b.
Description: Dark grey calcareous shales, with crinoidal and fossiliferous limestone beds, sometimes sandy. The formation overlies the Landelies Fm.
Stratotype: Not exposed at present.
Area: Western HSA (Tournai area).
Thickness: 60 m in the Tournai borehole and 58 m in the Leuze borehole.
Age: Latest Hastarian (based on the macrofauna, Paproth et al., 1983).