Cenozoic History of the Bering Land Bridge

Many facts of paleontology and biogeography (1, 2) indicate that the Old and New Worlds have sometimes been connected by a continuous land route that extended from Alaska across the present shallow floors of the Bering and Chukchi seas (Fig. 1) to Siberia. Recent geologic studies in western Alaska permit a more detailed consideration of the times at which the land bridge existed during the last 50 million years of Tertiary and Quaternary time. Some wellfounded inferences can also be drawn concerning the climate and vegetation that prevailed on the land bridge during the last (Wisconsin) glacial interval, the most recent period during which the land bridge existed (3).