The Chesapeake Bay is the largest estuary in the United States. It is located off the Atlantic Ocean and is surrounded by states of Virginia and Maryland. The Chesapeake Bay's watershed covers an area of 64,299 square miles (166 534 km²) in the District of Columbia and all or part of six states including New York, Pennsylvania, Delaware, Maryland, Virginia, and West Virginia. There are more than 150 rivers and streams that drain into this particular Bay.
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The Chesapeake Bay is around 200 miles (300 km) long, from the 'Susquehanna River' in the north to the Atlantic Ocean in the south.
Its narrowest point is near Annapolis, Maryland, where the Bay is 4 miles (6.4 km) wide.
Its widest point is close to the mouth of the 'Potomac River' where it is 30 miles (50 km) wide.
The total shoreline of the Bay and its tributaries is 11,684 miles (18,804 km), and the surface area of the bay and its major tributaries is 4,479 square miles (11,600 km²).
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The narrowest point of the bay is spanned by the Chesapeake Bay Bridge. The Chesapeake Bay Bridge-Tunnel spans a 17 mile (27 km) section of the bay near its mouth. |
Chesapeake Bay's geology, its form and location was affected by a bolide impact (an extraterrestrial body that collides with the Earth such as a meteor), which formed the Chesapeake Bay impact crater. This bolide hit the east shore of North America around 35.5 million years ago in the late Eocene epoch. It is one of the best preserved craters and the second largest in the U.S. The continued slumping of sediments over the rubble of the crater have helped shape Chesapeake Bay.
Some parts of the bay, particularly the larger parts by the coastline of Calvert County, are lined with cliffs as the result of receding waters millions of years ago. These cliffs, generally known as Calvert Cliffs, are famous for their fossils, especially fossilized shark teeth. Fossilized shark teeth are commonly found washed up on the beaches next to the cliffs.
Quite a lot of the bay is very shallow. At the point where the 'Susquehanna River' flows into the bay, the average depth is 30 feet, although this soon diminishes to an average of 10 feet from the city of Havre de Grace for about 35 miles, to just north of Annapolis. A person 6 feet 7 inches (2 metres) tall could traverse some 700,000 acres (2 800 km²) of the bay without being entirely submerged. On average, the depth of the bay is less than 30 feet or 9 metres.
The climate of the area surrounding the bay is mostly humid subtropical, with hot, very humid summers and mild, rainy winters. Only the area around the mouth of the Susquehanna River is continental in nature. The mouth of the Susquehanna River and the Susquehanna plains often freeze in winter.
The Chesapeake Bay was the site of the Battle of the Chesapeake in 1781, during which the French fleet defeated the Royal Navy in the decisive naval battle of the American Revolutionary War.
The largest rivers flowing into the bay, from north to south, are:
Susquehanna River
Patapsco River
Choptank River
Patuxent River
Potomac River
Rappahannock River
York River
James River
In the 1970s, the Chesapeake Bay contained one of the planet's first identified marine dead zones, where hypoxic waters were so depleted in oxygen they were unable to support life, resulting in massive fish kills. Large algae blooms, nourished by the runoff of farm and industrial waste throughout the watershed, prevent sunlight from reaching the bottom of the bay. The resulting loss of marine vegetation has depleted the habitat for many of the bay's animal creatures. One particularly harmful algae is Pfiesteria piscicida, which can affect both fish and humans. The depletion of oysters due to overharvesting and damaged habitat has had a particularly harmful effect on the quality of the bay. The bay's oyster industry has also suffered from two diseases: MSX and Dermo. Oysters serve as natural water filters, and their decline has further reduced the water quality of the bay. Water that was once clear for metres is now so turbid that a wader may lose sight of his feet before his knees are wet.
Efforts of federal, state and local governments, working in partnership through the Chesapeake Bay Program, and the Chesapeake Bay Foundation and other nonprofit environmental groups, to restore or at least maintain the current water quality have had mixed results. One particular obstacle to cleaning up the bay is that much of the polluting substances arise far upstream in tributaries lying within states far removed from the bay itself.
