Gulf of Mexico

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Gulf of Mexico


The Gulf of Mexico is a geographic area and a body of water that forms the so-called third coast of the contiguous United States. The Gulf of Mexico is surrounded on the United States side by coastlines of western and northern Florida, Alabama, Mississippi, Louisiana, and Texas. In Mexico, the Gulf is bordered by the states of Tamaulipas, Veracruz, Tabasco, Campeche, and Yucatán. The western end of the island of Cuba forms a partial barrier to the eastern Gulf of Mexico, where it joins the Caribbean Sea. The Gulf of Mexico is roughly oval-shaped with a long dimension of about 950 mi (1,500 km). The area of the Gulf of Mexico is about 615,000 square mi (1.6 million square km). For more than 500 years, the Gulf of Mexico has played a key role in the economic and political development of the United States, Cuba, and Mexico.

Historical Background and Scientific Foundations

The Gulf of Mexico is thought to have originated about 250 million years ago with the rifting or breaking apart of the tectonic plates of North America, South America, and Africa. When these components separated, an area of ocean floor developed between North and South America, which became the basin for the Gulf of Mexico. Not long after this basin was formed, sea water access to the basin was restricted and much of the sea water evaporated. We know this because today a large part of the deeper Gulf of Mexico basin is underlain by a thick layer of salt from this evaporation event. After an early dynamic history of crustal plate movement, the Gulf of Mexico basin became a stable area of Earth's crust and has remained so ever since.

Features of the Gulf of Mexico

The Gulf of Mexico is generally characterized by wide continental shelves around most of its periphery. These shelves, where water depths are at most a few hundred feet, have been the sites of intensive oil exploration in the past and to the present. The shelves give way to continental slopes, which lead down to the deeper plain of the Gulf of Mexico floor, which is known as the Sigsbee Deep. On the northern shelf of the Gulf of Mexico, an enormous pile of sediment from the Mississippi River delta has built a feature called the Mississippi sedimentary cone. This cone extends across the continental shelf and down the continental slope in front of the mouth of the Mississippi River.

Plastic and pliable salt from deep within the Gulf of Mexico basin has been squeezed up over time due to the weight of continental shelf and slope sediments. The upward movement of this buoyant salt has formed a submarine ridge on the northern continental shelf's outer margin, which is called the Sigsbee Ridge. In addition, numerous salt domes (conical salt intrusions) rise through the continental shelf sediments and in some places on land as a result of this pressure-related salt mobilization from below.

Geological History of the Gulf of Mexico

After salt deposition early in the Gulf's history, sediment began to gradually fill in this stable basinal area between continents. Sand, clays, and muds from the adjacent land areas of the northern Gulf of Mexico rim were continually washed into the Gulf basin by the Mississippi and other rivers. Much of this sediment came from sources in the Appalachian, Ouachita, and other adjacent uplifted mountains. In the Florida area and in the Yucatán area of Mexico, sediments of a chemical nature (calcium-carbonate precipitates and organic remains) filled in the basin.


RIVER DELTA: Flat area of fine-grained sediments that forms where a river meets a larger, stiller body of water such as the ocean. Rivers carry particles in their turbulent waters that settle out (sink) when the water mixes with quieter water and slows down; these particles build the delta. Deltas are named after the Greek letter delta, which looks like a triangle. Very large deltas are termed megadeltas and are often thickly settled by human beings. Rising sea levels threaten settlements on megadeltas.

SEDIMENT: Solid unconsolidated rock and mineral fragments that come from the weathering of rocks and are transported by water, air, or ice and form layers on Earth's surface. Sediments can also result from chemical precipitation or secretion by organisms.

SHORELINE: The band or belt of land surrounding a large body of surface water, such as a lake or ocean.

TECTONIC PLATE: Rigid unit of Earth's crust that moves about over geological time, merging with and separating from other tectonic plates as the continents rearrange but retaining its identity through these encounters. There are seven major tectonic plates on Earth and a number of smaller ones.

UPWELLING: The vertical motion of water in the ocean by which subsurface water of lower temperature and greater density moves toward the surface of the ocean. Upwelling occurs most commonly among the western coastlines of continents, but may occur anywhere in the ocean. Upwelling results when winds blowing nearly parallel to a continental coastline transport the light surface water away from the coast. Subsurface water of greater density and lower temperature replaces the surface water and exerts a considerable influence on the weather of coastal regions. Carbon dioxide is transferred to the atmosphere in regions of upwelling.

Starting about 160 million years ago, organic rich sediments were deposited in the Gulf of Mexico, which eventually became a key source layer for the Gulf's rich petroleum industry. Much of this petroleum became entrapped in a formation found through much of the northern Gulf rim called the Smackover Formation. Around 120 million years ago, a large reef system rimmed the western and northern Gulf of Mexico. These reefs, which were composed of now-extinct clams and associated shell fish, eventually formed some of the highly productive oil fields of eastern Mexico. Over the past 100 million years, the Gulf has remained a stable area, which is gradually being filled, mainly from the north and west, by sediment from sand- and clay-laden rivers.

Gulf of Mexico Economics

In addition to the oil production mentioned earlier, there is associated gas production from wells drilled into sediments of the Gulf of Mexico. Further, the Gulf has a highly valuable fishing production, both shell fish (for example, oysters) and swimming fish. The fishing industries of the Gulf coastal United States, Cuba, and Gulf coastal Mexico are supported by abundant living resources of the Gulf area. The continental margins of Florida and the Yucatán (Mexico) are situated in areas where deeper, cold, nutrient-rich waters in the Gulf rise through a process called upwelling. This provides for abundant growth of marine plankton, which in turn supports fish, shrimp, and squid harvesting.

The Gulf of Mexico has historically been an important avenue for shipping and there are many key ports on the Gulf, including New Orleans, Louisiana; Houston, Texas; and others. Gulf shores are well known as resort areas in Florida, Mississippi, Alabama, and parts of the Texas coast.

Gulf of Mexico Waters and Islands

Warm waters of the Gulf of Mexico are both a blessing and a curse. They give rise to the waters of the Gulf Stream, which flows north out of the Gulf and brings warmer waters to northern areas of the Atlantic. Such waters are a key factor in the success of the tourism industry mentioned earlier. Warm waters of the Gulf help fuel the intensity of tropical storms and hurricanes, which commonly enter the Gulf from sites in the western tropical Atlantic Ocean. Gulf of Mexico hurricanes, especially some in recent years such as Katrina, are famous for their potential for heavy damage and loss of life.

The Gulf of Mexico shoreline is notable for its barrier islands, which form end-to-end chains from Florida to eastern Louisiana and eastern Texas to eastern Mexico. These barrier islands are separated from the mainland by a narrow body of water such as a lagoon, bay, or estuary. Barrier islands are low-lying narrow strips of land that represent a delicate balance between sand availability, sea level, and coastal wave energy. The only parts of the Gulf shoreline that are not part of this barrier island trend are the marshy coasts of Louisiana and the Mexican coast (for example, along the Yucatán coast), where sand is not readily available.

Impacts and Issues

Like all bodies of water on Earth, the Gulf of Mexico responds to climatic change. For example, during times of warming climates, as today, higher sea surface temperatures cause intensification of cyclonic storms in the Gulf of Mexico. Communities and ecosystems along the Gulf of Mexico still remain especially vulnerable to disruption from storms after the record hurricane season of 2005 that included Hurricanes Katrina and Rita. The 2005 Atlantic hurricane season was the most active in recorded history. Also, sea level is rising in the Gulf of Mexico as it is globally today. Alternatively, during past times of much cooler global climates, the Gulf of Mexico was a much smaller body of water (due to lower sea level) and probably had far fewer cyclonic storms than today.

See Also Beach and Shoreline; Hurricanes; Sea Level Rise.



Gore, R. H. The Gulf of Mexico: A Treasury of Resources in the American Mediterranean. Sarasota, FL: Pineapple Press, 1992.

Web Sites

“Gulf of Mexico Integrated Science Data Information Management System.” U.S. Geological Survey, July 25, 2007. <> (accessed December 3, 2007).

GulfBase: Resource Database for Gulf of Mexico Research, 2007. <> (accessed December 3, 2007).

David T. King Jr.

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Gulf of Mexico

The Gulf of Mexico is a unique, semi-enclosed sea located between the Yucatan and Florida peninsulas, at the southeast shores of the United States. The Gulf of Mexico borders five of the 50 United States (Alabama, Florida, Louisiana, Mississippi, and Texas), and also Cuba and the eastern part of Mexico. Sometimes it is also called America's Sea. The Straits of Florida divides the Gulf from the Atlantic Ocean, while the Yucatan Channel separates it from the Caribbean Sea. The Gulf of Mexico covers more than 600,000 mi2 (almost 1.5 million km2), and in some areas its depth reaches 12,000 ft (3660m), where it is called Sigsbee Deep, or the "Grand Canyon under the sea." About two-thirds of the contiguous United States (31 states between the Rocky Mountains and the Appalachian Mountains) belongs to the watershed area of the Gulf of Mexico, while it receives freshwater from 33 major river systems, and many small rivers , creeks, and streams. This watershed area covers a little less than two million mi2(almost 5 million km2).

The currents in the Gulf of Mexico form a complex system. Its dominant feature is the Caribbean Current, coming from the warm Caribbean Sea by the Yucatan Channel, meandering around in the Gulf, then leaving through the Straits of Florida. Together with the Antilles Current, the Caribbean Current forms the Gulf Stream . The Gulf of Mexico has tides (the ocean waters' response to the Moon's and Sun's gravitational pull) of normally 2 ft (0.6 m) or less.

According to the modified Trewartha climate system, most of the Gulf Coast area is in the subtropical climate region with a summer precipitation maximum. The southern tip of the Yucatan Peninsula belongs to the savanna climate, and between the subtropical and the savanna lies a small area of tropical dry savanna. The hurricane season is between June and November, when hurricanes from the Atlantic Ocean, the Caribbean Sea, or the Gulf of Mexico can damage the Gulf shore, and beyond it. These hurricanes also help to balance the salinity of the water , while also moderating the atmosphere. The Gulf of Mexico plays an important role as a fuel injector for hurricanes before landfall, since major hurricanes are rapidly intensified by passing over deep and warm water.

The Gulf of Mexico has several environmental quality problems originating either from natural processes, or from anthropogenic pollution, or their combination. The problems range from erosion , and topsoil washing from the land into the Gulf, to oil spills and hazardous material spills, or trash washing ashore. These problems not only affect the estuaries, wetlands, and water quality in the Gulf, but have led to problems such as hypoxia (a zone of oxygen-depleted water), declining fish catch, contaminated fish, fish kills, endangered species, and air and water quality problems.

The role of the Gulf of Mexico is complex. The Gulf hosts important ocean currents (the area where hurricanes can gain strength before hitting land). The Gulf of Mexico and the Caribbean area contain some of the most spectacular wildlife in the world. The Gulf also partially supplies moisture for the North American Monsoon, and is also an important area for recreation and commercial fisheries. Many onshore refineries and offshore drilling platforms operate in the Gulf area, and produce about a quarter of the crude oil and almost one third of the natural gas in the United States. The Gulf also links the ports of the five southern states and Mexico with the ocean; about half of all the cargo shipped in and out of the United States travels through the Gulf. The Gulf of Mexico provides food, energy, jobs, recreation, and government revenue, not only benefiting the population on the shoreline of the Gulf, but the whole country.

See also Delta; Dunes; Estuary; Gulf stream; Petroleum extraction; Red tide; Rip current; Seawalls and beach erosion

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MEXICO, GULF OF. Bounded by the southern United States, eastern Mexico, and Cuba, this oval-shaped body of water has played a central role in North America's economic and political development. The Gulf of Mexico and its coastal beaches, estuaries, and islands have supplied varied peoples with abundant food and minerals. A warm current, the Gulf Stream, enters the gulf from the Caribbean Sea at the Strait of Yucatán and flows into the Atlantic at the Straits of Florida. The gulf's large mass of warm water shapes weather across the region, creating long growing seasons and violent tropical storms. The 600,000-square-mile gulf has been the site of important trade routes and settlements and a pivotal arena for imperial contests since Europeans first arrived in the Americas.

Diverse native societies once ringed the gulf, including complex Maya and Aztec civilizations in Mesoamerica, and Calusa, Chickasaw, Choctaw, Natchez, and Karankawa peoples in what became the United States. Spain first explored the gulf in voyages by Juan Ponce de León in 1513 and Alonso Alvarez de Pineda in 1519, and colonial outposts such as Havana and Veracruz rapidly followed. The gulf was a Spanish sea for nearly two centuries, and Spanish galleons took great quantities of silver and gold from the region. The French entered the gulf in about 1700, and the heart of their colonial effort was the Mississippi River and New Orleans, founded in 1718.

Imperial rivalries between Spain, France, and England dominated the region in the eighteenth century. The eventual winner, the United States, entered the scene in 1803 with the Louisiana Purchase. The Americans continued earlier patterns of growing rice, sugar, and cotton using slave labor, and New Orleans became their major gulf port. A powerful desire for new lands led to American acquisition of Florida, completed between 1810 and 1819. Florida and Texas were granted statehood in 1845, and the admission of Texas led to war with Mexico. The American victory in the Mexican-American War in 1848 confirmed the Rio Grande as the western edge of America's Gulf Coast. Expansion along the gulf ended there, as antebellum efforts to purchase Cuba for its sugar plantations and strategic position failed.

The security and stability of the Gulf of Mexico remained a significant foreign policy concern during the twentieth century. In 1898 the American victory in the Spanish-American War gave Puerto Rico to the United States, and Cuba became an American protectorate. The Panama Canal, begun in 1904, made shipping lanes in the gulf even more important. The United States intervened in the region many times in the twentieth century with its greatest focus on its complex Cold War relations with Cuba.

Military tensions in the gulf eased by the beginning of the twenty-first century, but environmental concerns increased as large numbers of Americans built homes along the Gulf or visited its beaches as tourists. In the twenty-first century the Gulf Coast remained a major agricultural region and the site of important fisheries, and after the 1940s it became a leader in oil, natural gas, and petrochemical production. The Gulf of Mexico has rich natural resources, but its many users put its productive waters and fragile coastlines and reefs at risk.


Gore, Robert H. The Gulf of Mexico: A Treasury of Resources in the American Mediterranean. Sarasota, Fla.: Pineapple Press, 1992.

Weber, David J. The Spanish Frontier in North America. New Haven, Conn.: Yale University Press, 1992.

William C.Barnett

See alsoCuba, Relations with ; Mexico, Relations with .

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Mexico, Gulf of

The Gulf of Mexico is a body of water that is bordered by the United States on the north and Mexico on the west and south; its eastern boundary is a line drawn from the western tip of the Florida Keys to the northeastern corner of the Yucatán Peninsula. The European discoverer of the Gulf was Sebastián de Ocampo, who sailed around the western end of Cuba in 1508. The earliest maps referred to the Gulf as Seno Mejicano or Golfo de la Nueva España, but it was named Golfo Mexicano on the 1569 Mercator map. The Gulf covers about 590,000 square miles and is bordered by continental shelves that vary between 30 and 90 miles in width. The Campeche Bank on the northern and western coasts of the Yucatán, however, is 150 miles wide at its greatest extent. The Sigsbee Depression, located toward the western side of the basin, forms the deepest point in the Gulf—13,124 feet.

The geologic history of the Gulf of Mexico is related to the breakup of Pangaea, the ancient continent that held all the world's landmasses, between 200 million and 300 million years ago. The Gulf began to form 130 million to 150 million years ago with the separation of North and South America, but its final shape was realized only within the last 30 million years.

The Gulf is dominated by a northward flow of water formed by the part of the South Equatorial (Caribbean) Current that rushes through the Yucatán Channel. This flow divides and curves east and west along the Gulf's north shore. The eastward-flowing waters pass through the Florida Straits to form the Gulf Stream. The waters of the Gulf are quite warm, varying between 73 and 84 F, and this creates the warm, wet maritime tropical air mass that affects the climate of the adjacent mainlands. The warm waters of the Gulf also contribute to the formation or strengthening of hurricanes that cross the Gulf to strike either the United States or the Mexican mainland. The 1995 hurricane season was one of the most active ever recorded. There were twenty-one named storms, and five crossed the northeastern Gulf of Mexico.

One of Mexico's most important resources is petroleum, and production areas on the Gulf continental shelves include the Marine Golden Lane off Tampico and the Akal and Bacab fields on the Campeche Bank, discovered in the mid 1970s. In 2006 oil companies discovered a massive reserve of oil in U.S.-owned Gulf waters that could conceivably boost oil reserves by fifty percent. Veracruz was Mexico's leading port during the colonial period and the nineteenth century, and Gulf ports still account for 75-80 percent of Mexico's maritime foreign commerce.

See alsoFlorida, Spanish West; Petroleum Industry; Yucatán.


Jorge Tamayo, Geografía general de México, 2d ed., vol. 2 (1962), pp. 626-644.

Robert S. Weddle, The Spanish Sea: The Gulf of Mexico in North American Discovery, 1500–1685 (1985).

Additional Bibliography

Barbosa, Fabio. "Petróleo en los hoyos de dona: Una Mirada a lo desconocido. (El petróleo en los hoyos de dona y otras dreas desconocidas del Golfo de México." Translated by David Shields. Siempre 50, no. 2649 (March 2004): 48-50.

Gore, Robert H. The Gulf of Mexico. Sarasota, FL: Pineapple Press, 1992.

Grafenstein, Johana von, Laura Muñoz Mata, and Antoinette Nelken-Terner. Un mar de encuentros y confrontaciones: El Golfo-Caribe en la historia nacional. México, D.F.: Secretaría de Relaciones Exteriores, 2006.

Rezak, Richard, Tom J. Bright, and David W. McGrail. Reefs and Banks of the Northwestern Gulf of Mexico: Their Geological, Biological, and Physical Dynamics. New York: John Wiley and Sons, 1985.

Skerritt Gardner, David. Colonos franceses y modernización en el Golfo de México. Veracruz, México: Universidad Veracruzana, 1995.

Trujillo Bolio, Mario A. El Golfo de México en la centuria decimonónica: Entornos geográficos, formación portuaria y configuración marítima. México D.F.; CIESAS, 2005.

                                        John J. Winberry