Eocene Series Epoch

the middle division of the Paleogene system (period). The name was introduced in 1833 by the British geologist C. Lyell. In 1855 the Upper Eocene was singled out as the Oligocene, and in 1874 the Lower Eocene was defined as the Paleocene.

The Eocene is divided into three subseries: Lower, Middle, and Upper. Nummulites, large foraminifers used to identify sub-series and zones, were widespread in the tropical seas of the Eocene. The Eocene is divided into stages according to local patterns. Four stages are identified in the USSR: Bakhchisarai, Simferopol’, Bodrak, and Alma. In Western Europe there are three stages: Ypresian, Lutetian, and Priabonian. [SeePALEOGENE SYSTEM (PERIOD); PALEOCENE SERIES (EPOCH); and OLIGOCENE SERIES (EPOCH).]

In the USSR deposits of petroleum (the Carpathians, the Northern Caucasus, and Fergana) and brown coal (the Ukraine and Eastern Siberia) are associated with Eocene beds, as well as deposits of phosphorites (Chernigov, the Donets Basin, and Turgai), diatomites (the Voronezh Anteclise and the Western Siberian Plain), iron ore (the Western Siberian Plain), and bleaching clays (askanite in the Caucasus).