2.5.5 Hosdin Formation - HOS

Author: Verniers, 1976 ms, 1983a.

Description: Dark to medium grey mudslate, siltslate, siltstone and fine sandstone with quartzic pelite in the e-division; Tde sequences are often present (74%) and medium thick (17 cm on average); only one Tbcde sequence is observed (14.2 cm thickness); Tcde sequences are often present (24%) and thick (26 cm average); c-divisions are mostly thin, ranging from 0.5 to 18.5 cm and averaging 6.9 cm. Both lower and upper boundaries have not been observed and are unknown, because the formation is bordered north and south by important faults.

Stratotype: Village Latinne, section in the abandoned railway section south-west of the hamlet Hosdin, at the locality Trou du Loup; outcrop HH-6 in Verniers (1983).

Area: Until now only observed in the Mehaigne valley.

Thickness: Recorded sections: 11.5 m, outcropping sections: >55 m, estimated thickness of formation: >150 m.

Age: Telychian, upper Llandovery based on chitinozoan assemblage with Conochitina vitrea (= Conochitina sp. A in Verniers, 1982).

(J. VERNIERS)