Skip to main content
U.S. flag

An official website of the United States government

Harry at the Cliffs

Detailed Description

 Harry Dowsett is explaining the significance of these beds of the Calvert Formation that are exposed along Calvert Cliffs on the west side of the Chesapeake Bay. Beds 11, 12, and 13 (shown here) were deposited during the Middle Miocene Climatic Optimum, about 17 to 14 million years ago. Like today, the warming during the MMCO was driven by large and rapid CO2 emissions. 


Public Domain.