ABSTRACT
The geologic formations of the Chesapeake Bay area contain a detailed record of the oceanographic history of the Miocene Epoch. When the Earth entered periods of global warming during the Miocene, the polar ice caps and high-latitude glaciers melted, raising sea levels and flooding the coastal plain areas. In times of global cooling, the ice caps and glaciers rebuilt, sea level plummeted, and the coastal areas again became dry land. During times of marine flooding (transgressive intervals), thick beds of shells were deposited, and their distribution defines the extent of the oceanic incursion. Sea level lows (regressive intervals) are represented by either missing layers (unconformities) or by layers of terrestrial or unfossiliferous near-shore sediments.
