Calvert Cliffs State Park is a state park in [[Calvert County, Maryland, situated on the Chesapeake Bay. On the 1612 John Smith of Jamestown map, the site was called Rickard's Cliffes. The park is located in Lusby, Maryland.
Geology and paleontology
The park is known for the abundance of mainly Middle Miocene sub-epoch fossils, which can be found on the shoreline. It contains the type locality site of the Early to Middle Miocene Calvert Formation. These rocks are the sediment from a coastal ocean that covered the area during that time. The age of the formation is (19-)18-15(-14) million years, i.e. it extends essentially over the Hemingfordian stage. This formation occurs in Maryland and neighboring Virginia.
In addition, rocks of the younger Choptank and the St. Marys Formations are exposed. This makes Calvert Cliffs State Park highly interesting for paleoclimatology and paleontology, because the accessible strata provide a good record of the Middle Miocene Climate Transition and documents a minor mass extinction event, the Middle Miocene disruption.
This formation is notable for the plentiful fossil shark teeth found therein. Especially popular among "rockhounds" are those from giants such as Carcharocles and the famous Megalodon (which is often included in Carcharocles). Some remains of a prehistoric loon (Gavia) are also believed to be from the Calvert Formation; they are the oldest known record of that genus known from North America. Collecting can be done on the beach as access to the Cliffs is no longer available due to erosion.
The ancestral baleen whale Eobalaenoptera harrisoni and the merganser Mergus miscellus were described from the Virginian part of the formation. From the uppermost layer, deposited 15-14 million years ago, they represent the oldest known member of their family and genus, respectively.