Age of the Cape Kennedy Barrier-and-Lagoon Complex

Thorium and uranium isotopic analyses of both modern and fossil shells and beach rock of the Cape Kennedy, Florida, area suggest that the materials can be treated as closed, datable systems that have experienced a brief open period after deposition (but before burial) during which both uranium and thorium were incorporated. An isochron method of correction for addition of Th230 is applied, based on results from the modern materials. Two periods of deposition before the present are indicated: one at about 110 thousand years ago, and another, less extensive, at about 30 thousand years ago. These deposits appear to represent the only high sea level stands of the Pleistocene in the area.