The Chesapeake Bay is the nation's largest estuary. An estuary is a semi enclosed basin with fresh water flowing in at one end and salt water coming in at the other. There are many famous rivers that drain into the Chesapeake Bay. These include the Potomac, Susquehanna, York, and James.
Scientists offer a couple of explanations about how the Bay was formed.
One was that a meteorite hit the ocean thirty-five million years ago. This meteorite would have punched through the ocean, which was then rock, and left a hole twice as big as Rhode Island. The researchers say the meteorite impact left a dent in the continental shelf. Today that dent is known as the Chesapeake Bay. Another theory is that the bay formed after the last glaciers shaped the eastern seaboard.