SANTONIAN STAGE

the fourth of six main divisions (in ascending order) of the Upper Cretaceous Series, representing all rocks worldwide that were deposited during the Santonian Age (87.5 to 84 million years ago). The stage's name derives from the town of Saintes in western France, the area surrounding which is the classic type district for rocks of this age. The Santonian Stage is represented in northern Europe by the Granulaten Chalk, in England by part of the Upper Chalk, and in the United States by part of the Niobrara Chalk. Though it does not occur in the type district, the biozone of the ammonite cephalopod Texanites texanum is widely used to mark the base of the stage in regions as distant as Texas, Japan, southern Africa, Madagascar, and the Middle East. The biozones of the calcareous nannofossils Marthasterites furcatus and Lithastrinus grilli and of the planktonic foraminiferans Marginotruncana carinata and M. concavata are also considered diagnostic for rocks of this stage. The Santonian overlies the Coniacian Stage and underlies the Campanian Stage.