Arundel Clay

The Arundel Formation, also known as the Arundel Clay, is a clay-rich sedimentary rock formation, within the Potomac Group, found in Maryland of the United States of America. It dates to the Early Cretaceous, and is of late Aptian or early Albian age. This rock unit had been economically important as a source of iron ore, but is now more notable for its dinosaur fossils. It is named for Anne Arundel County, Maryland.