Geoscience Reference
In-Depth Information
and Barnegat Bay in New Jersey, the Outer Banks of North Carolina, and Albermarle and Pamlico Sounds are
prime examples of these paired barrier island-estuarine systems along the Mid-Atlantic coast. The other major
estuaries, Delaware and Chesapeake Bays, were created as the rising sea flooded river valleys that had been
gouged out by raging rivers from glacial meltwater during the last ice age, when sea level was as much as 100
meters (300 feet) lower.
The more southerly Chesapeake Bay is in a class by itself as the largest estuary in the United States. Half of
its water volume derives from the Atlantic Ocean, matched by fresh waters that flow toward the sea from a
massive drainage basin of 166,000 square kilometers (64,000 square miles), including parts of New York,
Pennsylvania, West Virginia, Delaware, Maryland, and Virginia. The southern New England portion of the
coastline includes Long Island Sound and Narragansett Bay.
The Gulf Stream begins to veer away from the coast north of Cape Hatteras, but occasionally a northward-
bending meander breaks off the stream to form an eddy, or ring, that traps warm Sargasso Sea water in its cen-
ter. These warm core rings are typically 100 to 200 kilometers (60 to 120 miles) across and can extend to a
depth of 1,500 meters (4,900 feet). They are the only mechanism whereby warm tropical water can be trans-
ported from south of the Gulf Stream to north of it. Although these warm waters from the Sargasso Sea have
relatively low levels of biological production, they sometimes transport tropical fish and sea turtles into the
cool waters of the continental shelf in the Mid-Atlantic Bight.
