Tortonian Stage
Tortonian Stage
the upper stage of the Middle Miocene of the Neogene system of Western Europe. It was identified in 1857 by the Swiss geologist K. Mayer-Eymar in northern Italy. It is represented by blue marls with deepwater fauna characterized by mollusks. The corresponding stages in the northern part of the European USSR are the Karagan and Konka [seeNEOGENE SYSTEM (PERIOD)].