Hauterivian Stage

(after the town of Hauterive in Switzerland), the third lowest stage of the Cretaceous system, first identified in 1874 in the Jura Mountains of France by E. Renevier, who attributed the bluish marls and overlying yellowish zoogenic and oolitic limestones in a standard cross section near Hauterive to this stage. Numerous sea urchins, bivalves, and ammonites are found in these rocks (in particular, in the marls); they are especially important for identifying the stage. In the USSR, deposits of the Hauterivian stage are well developed in the Carpathians, the Crimea, the Caucasus, the Kopet Dagh, and the Mangyshlak Peninsula. Clays and sandstones are predominant in a Hauterivian stage; in the Transcaucasus, limestones are widespread. In the Eastern European Platform the lower section of the clays, characterized by unique ammonites of the genus Simbirskites, may be part of the Hauterivian stage.