From the album: Calvert Cliffs
Along the edge of the cliffs there are three major formations. The youngest of these three is known as the St. Mary's formation which began forming during the Miocene. This is a chunk taken out of the St. Mary's formation. As you can see, these formations produce evidence of prehistoric marine life. See: http://www.mgs.md.gov/esic/brochures/ccliffs.html