The
Gulf of Mexico is the ninth largest
body of water in the world. It is an ocean basin largely surrounded by the
North American continent and the island of
Cuba. It is bounded on the northeast, north and northwest by the
Gulf Coast of the United States, on the southwest and south by
Mexico, and on the southeast by
Cuba. The shape of its basin is roughly oval and approximately 810
nautical miles (1,500 km) wide and filled with sedimentary rocks and debris. It is part of the
Atlantic Ocean through the
Florida Straits between the U.S. and Cuba, and with the
Caribbean Sea (with which it forms the
American Mediterranean Sea) via the
Yucatan Channel between Mexico and Cuba.
Tidal ranges are extremely small due to the narrow connection with the ocean. The gulf basin is approximately 615,000
mi² (1.6 million km²). Almost half of the basin is shallow intertidal waters. At its deepest it's 14,383 ft (4,384 m) at the
Sigsbee Deep, an irregular trough more than 300
nautical miles (550 km) long.
It was probably formed approximately 300 million years ago as a result of the seafloor sinking. There is evidence that the
Chicxulub Crater was formed when a large
meteorite hit the earth 65 million years ago which may have led to the
Cretaceous–Tertiary extinction event.
History
Formation
Little is known about the geologic history of the Gulf of Mexico Basin before
Late Triassic time. Some authors have postulated the presence of a basin in the area during most of
Paleozoic time, but most evidence seems to indicate that Paleozoic rocks don't underlie most of the Gulf of Mexico basin and that the area was, at the end of Paleozoic time, part of the large supercontinent of
Pangea, the result of the collision of several continental plates.
The present Gulf of Mexico basin is believed to have had its origin in Late Triassic time as the result of rifting within the
North American Plate at the time it began to crack and drift away from the
African and
South American plates. Rifting probably continued through Early and Middle
Jurassic time with the formation of "stretched" or "transitional"
continental crust throughout the central part of the
basin. Intermittent advance of the sea into the continental area from the west during late Middle Jurassic time resulted in the formation of the extensive
salt deposits such as the
Brine pool. It appears that the main drifting episode, during which the
Yucatan block moved southward and separated from the North American Plate and true oceanic crust formed in the central part of the basin, took place during the early
Late Jurassic, after the formation of the salt deposits. The Gulf's southwestern and southern shores lie along the
Mexican states of
Tamaulipas,
Veracruz,
Tabasco,
Campeche,
Yucatán, and the northernmost tip of
Quintana Roo. On the southeast it's bordered by
Cuba. It supports major American, Mexican and Cuban fishing industries. The outer margins of the wide continental shelves of Yucatán and Florida receive cooler,
nutrient-enriched waters from the deep by a process known as
upwelling, which stimulates plankton growth in the
euphotic zone. This attracts fish, shrimp, and squid. River drainage and atmospheric fallout from industrial coastal cities also provide nutrients to the coastal zone.
The
Gulf Stream, a warm Atlantic Ocean current and one of the strongest
ocean currents known, originates in the gulf, as a continuation of the
Caribbean Current-Yucatán Current-
Loop Current system. Other circulation features include the anticyclonic
gyres which are shed by the
Loop Current and travel westward where they eventually dissipate, and a permanent cyclonic
gyre in the
Bay of Campeche. The
Bay of Campeche in Mexico constitutes a major arm of the Gulf of Mexico. Additionally, the gulf's shoreline is fringed by numerous bays and smaller inlets. A number of rivers empty into the gulf, most notably the
Mississippi River in the northern gulf, and the
Grijalva and
Usumacinta Rivers in the southern gulf. The land that forms the gulf's coast, including many long, narrow barrier islands, is almost uniformly low-lying and is characterized by marshes and swamps as well as stretches of sandy beach.
The
continental shelf is quite wide at most points along the coast, most notably at the Florida and
Yucatán Peninsulas. The shelf is exploited for its
oil by means of offshore drilling rigs, most of which are situated in the western gulf and in the
Bay of Campeche. Another important commercial activity is fishing; major catches include red snapper, amberjack, tilefish, swordfish, and various grouper, as well as shrimp and crabs. Oysters are also harvested on a large scale from many of the bays and sounds. Other important industries along the coast include shipping, petrochemical processing and storage, military use, paper manufacture, and tourism.
The gulf's warm water temperature can feed powerful Atlantic
hurricanes causing extensive human death and other destruction as happened with
Hurricane Katrina in 2005. In the Atlantic, a hurricane will draw up cool water from the depths and making it less likely that further hurricanes will follow in its wake (warm water being one of the preconditions necessary for their formation). However, the Gulf is shallower and its entire water column is warm. When a hurricane passes over, although the water temperature may drop it soon rebounds and becomes capable of supporting another tropical storm.
The Gulf is considered
aseismic: however, mild tremors have been recorded throughout history (usually 5.0 or less on the
Richter scale). A 6.0 tremor was recorded on
September 10,
2006, 250 miles off the coast of
Florida which caused no damage, but could be felt throughout the
Southeastern United States. No damage or injuries were reported.
Earthquakes such as this may be caused by interactions between sediment loading on the sea floor and adjustment by the crust.
Pollution
Because of the ever increasing amount of
nitrogen and
phosphates dissolved in the waters of the Gulf of Mexico, pollution has more than doubled since
1950. Current estimates suggest that three times as much nitrogen is being carried into the Gulf today compared with levels 30 years ago or at any time in history in the water. Every summer there's now an area south of the Louisiana coastline, larger than the
U.S. state of
Massachusetts at over 7,000 mi² (18,000 km²) that's
hypoxic. These waters don't carry enough
oxygen to sustain marine life. This annually enlarging
dead zone is a major threat to the fishing industry and to public health.
Also, there are frequent "
red tide" algae blooms that kill fish and marine mammals and cause respiratory problems in humans and some domestic animals when the blooms reach close to shore. This has especially been plaguing the southwest Florida coast, from the
Florida Keys to north of
Pasco County, Florida.
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