Chesapeake Bay
The
Chesapeake Bay is the largest
estuary in the United States. It lies off the
Atlantic Ocean, surrounded by
Virginia and
Maryland. The Chesapeake Bay's
watershed covers 64,299
mi² (166 534
km²) in the
District of Columbia and parts of six states:
New York,
Pennsylvania,
Delaware,
Maryland,
Virginia, and
West Virginia. More than 150 rivers and streams drain into the Bay.
The main stem of the Bay itself is 189
miles (304
km) long, from the
Susquehanna River in the north to the Atlantic Ocean in the south. At its narrowest point near
Annapolis, Maryland, the Bay is 4 miles (6.4 km) wide; at its widest point, near the mouth of the
Potomac River, it is 30 miles (50 km) wide. Total shoreline for the Bay is 11,684 miles (18 804 km), and the surface area of the Bay and its major tributaries is 4,479 mi² (11 600 km²).
The narrowest point of the Bay is spanned by the
Chesapeake Bay Bridge. The
Chesapeake Bay Bridge-Tunnel spans a 23 mile (37 km) section of the Bay at near its mouth.
The Bay is the of the Susquehanna, meaning that was where the river flowed when sea level was lower. It is
not a
fjord because the
Laurentide Ice Sheet never reached as far south as the northernmost point on the bay. Rather, the Bay's geology and its present form and its very location have also been affected by a
bolide impact event at the end of the
Eocene (about 35.5 million years ago), forming the
Chesapeake Bay impact crater.
Parts of the Bay, especially the big parts by the coastline of
Calvert County, are lined by 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.
Scientist's Cliffs is a beach community in
Calvert County, named so because of the cliffs' propensity for geological finds and numerous fossils.
Much of the bay is quite shallow. At the point where the Susquehanna River flows into the bay the average depth is 30', although this soon diminishes to an average of 10' from the city of Havre de Grace for about 35 miles, to just north of Annapolis. A person 6 feet 7 inches (2
m) 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
meters.
The climate of the area surrounding the bay is primarily
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, and the mouth of the Susquehanna River and the Susquehanna flats often freeze in winter.
Since the Bay is an estuary it has fresh water and brackish water. Brackish water has 3 salinity zones, oligohaline, mesohaline, and polyhaline. The salinity is measured on parts per thousands (ppt). The fresh water zone runs from the mouth of the Susquehanna River to north Baltimore. The oligohaline zone has very little salt. salinity veries from 0.5ppt-10ppt and freshwater species can survive there. The north end of the oligohaline zone is north Baltimore and the south end is the Chesapeake Bay Bridge. The mesohaline zone has a medium amount of salt and runs from the Bay Bridge to the mouth of the Rapahannock River. the salinity ranges from 10.7ppt-18ppt. The polyhaline zone is the saltiest zone and some of the water can be as salty as sea water. It runs from the mouth of the Rapahannack River to the mouth of the Bay.The salinity ranges from 18.7ppt-36ppt. 36ppt is as salty as the ocean.
The Chesapeake Bay was first explored and mapped by
Captain John Smith during his explorations between
1607 and
1609. As of July 2006, two bills are circulating in the U.S. Congress to establish a Captain John Smith Chesapeake National Historic Trail.
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.
Today, the
Calvert Cliffs Nuclear Power Plant uses water from the Bay to cool its reactor.
The bay is also known for the
Chesapeake Bay Retriever, a
dog breed developed in this area.
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 RiverThe word
Chesepiooc is an
Algonquian word meaning "Great Shellfish Bay." The Bay was once known for its great seafood production, especially
blue crabs,
clams and
oysters. The plentiful oyster harvests led to the development of the
Skipjack, the State Boat of Maryland, which is the only remaining working boat type in the
United States still under sail power. Today, the body of water is less productive than it used to be, because of runoff from urban areas (mostly on the western shore) and farms (especially on the
eastern shore), overharvesting, and invasion of foreign species. The bay though, still yields more
fish and
shellfish (about 45,000 short
tons or 40 000
tonnes yearly) than any other estuary in the United States.
The Bay is famous for its
rockfish, also known as
striped bass. Once on the verge of extinction, rockfish have made a significant comeback and are now able to be fished in strictly controlled and limited quantities.
The Bay serves as the predominate source of
eel in the United States.
In
2005, local governments began debate on the introduction to certain parts of the Bay of a species of asian
oyster, to revive the lagging shellfish industry.
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.
*
Delmarva Peninsula*
Dead zone (ecology)*
Chesapeake, a novel by author
James A. Michener*
Chesapeake Bay Program*
Chesapeake Bay Journal*
Chesapeake Bay Gateways Network*
Chesapeake Bay Foundation*
Alliance for the Chesapeake Bay*
Chesapeake Research Consortium*
Chesapeake Community Modeling Program*
Chesapeake Bay Bridge (near Annapolis, MD)*
Chesapeake Bay Bridge-Tunnel*
Maryland Sea Grant*
Scientist's Cliffs*
National Geographic- Saving The Chesapeake*
National Geographic- Exploring The Chesapeake Then and Now*
John Smith Water Trail Blog - Musings and Meanders on the Chesapeake Bay*
Captain John Smith Chesapeake National Historic Water Trail
