Importance des constructions algaires dues a des cyanophycees dans les formations continentales du Cretace superieur et de l'Eocene du Languedoc

Abstract

The upper Cretaceous and lower Tertiary continental sediments of the Languedoc region, in southern France, contain numerous fossil algal structures of various shapes and sizes, previously supposed to be concretions. The algae principally represented are forms with affinities to living Rivularia haematites of the Cyanophyceae. The morphology of the structures varies with the mode of deposition. Forms subject to flood currents are algal balls and incrustations on shells. Those in calmer zones are characterized by larger cylindrical forms.