The Tufs et calcaires de Rosan () is a geologic formation in France. It preserves fossils dating back to the Katian to Hirnantian (Kralodvorian to Kosovian in the regional stratigraphy) stages of the Late Ordovician period.Tufs et calcaires de Rosan at Fossilworks.org
Fossil content The formation has provided fossils of:Melou, 1990
Strophomenata
Hedstroemina sp. Iberomena sp. Leptaena sp. Leptestiina sp.
Rhynchonellata
Porambonites sp. Eoanastrophia sp. Rostricellula sp. ?Dalmanella sp. Bancroftina sp. Nicolella sp. Retrorsirostra sp. Ptychopleurella sp. Dolerorthis sp. Mcewanella sp. Aberia sp. ?Rhactorthis sp.
See also List of fossiliferous stratigraphic units in France
References
Bibliography M. Melou. 1990. Brachiopodes articules de la coupe de l'ile de Rosan (Crozon, Finistere); formation des tufs et calcaires de Rosan (Caradoc-Ashgill). Géobios 23(5):539-579