Potassium-argon dating of the Tertiary f (sub 1-2) stage in New Guinea and its bearing on the geological time-scale

Abstract

An unequivocally Hemphillian fauna of the Bone Valley type is described from the Manatee County dam site. Three habitats (savannah, stream, and estuary) are present. Sharks are the most abundant; these today range into estuarine and fresh-water streams. If the land has been stable tectonically since at least Miocene, then the sea dropped as low as the level of the Manatee site, 6 feet above present sea level. Evidence of eustatic fluctuations of over 90 feet during Hemphillian time is present. A horse species and a tortoise are reported from the eastern U.S. for the first time, and other genera and species are discussed and described.