HAUTERIVIAN STAGE

the third of six divisions (in ascending order) in the Lower Cretaceous Series, representing all those rocks on a global basis deposited during the Hauterivian Age (131 to 124 million years ago). No global stratotype section and point (GSSP) for the base of the Hauterivian Stagei.e., worldwide standard for defining the stratigraphic boundaryhas been approved by the International Commission on Stratigraphy (under the direction of the International Union of Geological Sciences). Many different and conflicting stage names have been proposed for the internal divisions of the Cretaceous System, but the present scheme conforms closely to the order imposed by the French geologist Alcide Dessalines d'Orbigny in the mid-19th century. The name of the stage is derived from the village of Hauterive in Switzerland, the surrounding area of which serves as the classic type district for rocks of this age. The Hauterivian Stage is represented in northern continental Europe by part of the thick Hils clay, whereas in England it includes the middle part of the Wealden sandstones and clays. The base of the stage is defined by the first appearance of the ammonite cephalopod Acanthodiscus radiatus and related species. The planktonic foraminifera biozone of Caucasella hoterivica is also considered diagnostic for rocks of this age. Rocks of the Hauterivian Stage overlie those of the Valanginian Stage and underlie rocks of the Barremian Stage.