Hauterivian

The Hauterivian is a stage of the Early Cretaceous epoch. It is the second stage of the Early Cretaceous, fitting between the Valanginian in the early part of the century and the Barremian later in the century. In approximate terms, it spans about 132 to 129 million years ago. As a standard of International Chronostratigraphy, the Hauterivian is used to segment marine and coastal deposits of that time for correlations across regions.

The name Hauterivian derives from Hauterive, a locality in Switzerland, where rocks of this age were studied and described. The term has been in use since the 19th century as part of the European framework for subdividing the Early Cretaceous, and it is now adopted in formal stratigraphic scales used worldwide.

Stratigraphically, the Hauterivian is characterized in many regions by distinctive marine fossil assemblages, particularly ammonites and other ammonoid coquinas that enable regional biostratigraphy. The base of the Hauterivian is typically correlated with reorganization in ammonite faunas and other microfossil shifts, while its top is marked by the appearance of faunal assemblages associated with the ensuing Barremian. Global correlations rely on these fossil markers, in combination with other lithologic indicators and, where available, radiometric data from intercalated volcanic layers or well-dated ash beds.

Paleogeographically, the Hauterivian occurred during a time of generally warm global climate with higher eustatic sea levels, leading to widespread shallow seas in parts of Europe and the northern Tethys realm. The stage records a diverse marine biota and provides important biostratigraphic markers for correlating Early Cretaceous sections around the world.