The Tereñes Formation or Tereñes Marl is a Late Jurassic (Kimmeridgian) geologic formation in Asturias, Spain. The grey marls of the formation were deposited in a lagoonal environment at a muddy coast along a temporary inland sea. The lower section of the formation comprises silty and chalky sandstones with desiccation cracks and ripple marks, then becomes a bituminous, prominently ostracod-bearing, pelecypod shell chalk, lime chalk marl and marl. Fossil tracks have been reported from the formation.

Fossil content

The following fossils were reported from the formation: