Xert Formation

Xert Formation
Stratigraphic range: Late Barremian ~122–120 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Underlies	Forcall Formation
Overlies	Artoles Formation, Arcillas de Morella Formation
Lithology
Primary	Limestone, marl
Other	Claystone, chert
Location
Coordinates	40°42′N 0°06′E / 40.7°N 0.1°E / 40.7; 0.1
Approximate paleocoordinates	30°06′N 10°12′E / 30.1°N 10.2°E / 30.1; 10.2
Region	Aragón
Country	Spain
Extent	Maestrazgo Basin  Galve Basin
Type section
Named for	Chert
Xert Formation (Spain) Show map of Spain Xert Formation (Aragon) Show map of Aragon

The Calizas y margas de Xert Formation or Xert Formation is an Early Cretaceous (late Barremian) geologic formation of the Maestrazgo and Galve Basins in central-eastern Spain. The formation is described as a coastal claystone, with indications of a transgressive episode, marked by the transition from marsh facies, with little marine influence, to marine platform facies evidenced by abundant marine invertebrates.^[1]