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In the low-energy estuary, without strong river currents to flush away the sediments, the Exmore Channel filled up.

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Chesapeake Bay bathymetry Source: National Oceanic and Atmospheric Administration (NOAA) National Geophysical Data Center The bay is a feature on the Coastal Plain.

The Coastal Plain east of I-95 was created over the last 150-200 million years by erosion from the Appalachian Mountains and by deposition of sediments at the bottom of the Atlantic Ocean.

The Chesapeake Bay fills the drowned valleys of the Susquehanna and James rivers, plus tributaries that intersected the Susquehanna.

The current shape of the bay is less that 10,000 years old - so Native Americans arrived in in Virginia in time to witness the conversion of multiple freshwater river channels into the brackish estuary of the modern Chesapeake Bay.

The Exmore Channel, the oldest paleochannel dating back to 300,000-500,000 years ago, was the path of the combined Susquehanna and Potomac rivers east across the Continental Shelf.

After sea level rose and covered the Continental Shelf, an estuary formed at the ancient mouth of the Susquehanna River.

To get around the barrier of the Accomack Spit, the mouth of the Belle Haven channel reached the Atlantic Ocean south of the old Exmore Channel, roughly at the latitude of today's Rappahannock River.

When sea levels rose again as ice sheets melted on the continents, an estuary developed at the mouth of the Belle Haven channel.

Deltas, with barrier islands and spits, formed at river mouths during the periods of high sea level ("highstands").

When sea levels dropped, an ancestor of today's river carved a new channel nearby, seeking the easiest path to the ocean - but bypassing the old river mouth, now blocked by accumulated sediments.

a fjord created by a glacier Source: National Park Service, Those Fabulous Fjords!

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