Pensacola Bay is a bay located in the northwestern part of Florida , United States , known as the Florida Panhandle .
131-560: The bay, an inlet of the Gulf of Mexico , is located in Escambia County and Santa Rosa County , adjacent to the city of Pensacola, Florida , and is about 13 miles (21 km) long and 2.5 miles (4 km) wide. The Pensacola Bay estuarine system, which also includes Escambia Bay , Blackwater Bay , East Bay , Santa Rosa Sound , and the Escambia , Blackwater , Yellow , and East Bay rivers,
262-430: A brine pool 3,300 feet (1,000 m) below the gulf's surface, with a circumference of 100 feet (30 m) and 12 feet (3.7 m) feet deep, which is four to five times saltier than the rest of the water. The first exploration of the site was unmanned, using Hercules and in 2015 a team of three used the deep-submergence vehicle Alvin . The site cannot sustain any kind of life other than bacteria , mussels with
393-578: A hypoxic dead zone that runs east–west along the Texas–Louisiana coastline. In July 2008, researchers reported that between 1985 and 2008, the area roughly doubled in size. It was 8,776 square miles (22,730 km ) in 2017, the largest ever recorded. Poor agricultural practices in the northern portion of the Gulf of Mexico have led to a tremendous increase of nitrogen and phosphorus in neighboring marine ecosystems, which has resulted in algae blooms and
524-476: A magnitude 6.0 earthquake occurred about 250 miles (400 km) west-southwest of Anna Maria, Florida . The quake was reportedly felt from Louisiana to Florida. There were no reports of damage or injuries. Items were knocked from shelves and seiches were observed in swimming pools in parts of Florida. The earthquake was described by the USGS as an intraplate earthquake , the largest and most widely felt recorded in
655-420: A symbiotic relationship , tube worms and certain kinds of shrimp . It has been called the "Jacuzzi of Despair". Because it is warmer than the surrounding water (65 °F or 18 °C compared to 39 °F or 4 °C), animals are attracted to it but cannot survive once they enter it. The Gulf of Mexico is 41 percent continental slope , 32 percent continental shelf , and 24 percent abyssal plain with
786-439: A consequence, a powerful source generating plate motion is the excess density of the oceanic lithosphere sinking in subduction zones. When the new crust forms at mid-ocean ridges, this oceanic lithosphere is initially less dense than the underlying asthenosphere, but it becomes denser with age as it conductively cools and thickens. The greater density of old lithosphere relative to the underlying asthenosphere allows it to sink into
917-695: A documentary about the project, short videos and video updates during the expedition. Video footage from the ROV was an integral part of this outreach and used extensively in the Mystery Mardi Gras Shipwreck documentary. On July 30, 1942, the Robert E. Lee , captained by William C. Heath, was torpedoed by the German submarine U-166 . She was sailing southeast of the entrance to the Mississippi River when
1048-450: A few tens of millions of years. Armed with the knowledge of a new heat source, scientists realized that Earth would be much older, and that its core was still sufficiently hot to be liquid. By 1915, after having published a first article in 1912, Alfred Wegener was making serious arguments for the idea of continental drift in the first edition of The Origin of Continents and Oceans . In that book (re-issued in four successive editions up to
1179-704: A great harbor the master pilot Miruelo knew of. Sometime during these two days, one of the five remaining ships was lost on the rugged coast, but nothing else is known of it. In 1697 French sailor Pierre Le Moyne d'Iberville was chosen by the Minister of Marine to lead an expedition to rediscover the mouth of the Mississippi River and to colonize Louisiana which the English coveted. D'Iberville's fleet sailed from Brest on October 24, 1698. On January 25, 1699, d'Iberville reached Santa Rosa Island near Pensacola founded by
1310-487: A lack of available oxygen. Occurrences of masculinization and estrogen suppression were observed as a result. An October 2007 study of the Atlantic croaker found a disproportioned sex ratio of 61% males to 39% females in hypoxic sites. This was compared with a 52% to 48% male-female ratio found in reference sites, showing an impairment of reproductive output for fish populations inhabiting hypoxic coastal zones. According to
1441-475: 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
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#17328370554121572-571: A layer of basalt (sial) underlies the continental rocks. However, based on abnormalities in plumb line deflection by the Andes in Peru, Pierre Bouguer had deduced that less-dense mountains must have a downward projection into the denser layer underneath. The concept that mountains had "roots" was confirmed by George B. Airy a hundred years later, during study of Himalayan gravitation, and seismic studies detected corresponding density variations. Therefore, by
1703-572: A license to claim what is now the Gulf Coast of the United States, known as the Narváez expedition . The contract gave him one year to gather an army, leave Spain, be large enough to found at least two towns of 100 people each, and garrison two more fortresses anywhere along the coast. On April 7, 1528, they spotted land north of what is now Tampa Bay . They turned south and traveled for two days looking for
1834-400: A misnomer as there is no force "pushing" horizontally, indeed tensional features are dominant along ridges. It is more accurate to refer to this mechanism as "gravitational sliding", since the topography across the whole plate can vary considerably and spreading ridges are only the most prominent feature. Other mechanisms generating this gravitational secondary force include flexural bulging of
1965-510: A number of large tectonic plates , which have been slowly moving since 3–4 billion years ago. The model builds on the concept of continental drift , an idea developed during the first decades of the 20th century. Plate tectonics came to be accepted by geoscientists after seafloor spreading was validated in the mid-to-late 1960s. The processes that result in plates and shape Earth's crust are called tectonics . Tectonic plates also occur in other planets and moons. Earth's lithosphere,
2096-559: A permanent cyclonic gyre in the Bay of Campeche, as well as anticyclonic gyres which are shed by the Loop Current and travel westward where they eventually dissipate. The Bay of Campeche constitutes a major arm of the Gulf of Mexico. Additionally, the gulf's shoreline is fringed by numerous bays and smaller inlets. Stream that empty into the gulf include the Mississippi River and the Rio Grande in
2227-662: A result of plate tectonics . The Gulf of Mexico basin is roughly oval in shape and is approximately 810 nautical miles (1,500 km; 930 mi) wide. Its floor consists of sedimentary rocks and recent sediments. It is connected to part of the Atlantic Ocean through the Straits of Florida between the U.S. and Cuba, and with the Caribbean Sea via the Yucatán Channel between Mexico and Cuba. Because of its narrow connection to
2358-551: A secondary phenomenon of this basically vertically oriented mechanism. It finds its roots in the Undation Model of van Bemmelen . This can act on various scales, from the small scale of one island arc up to the larger scale of an entire ocean basin. Alfred Wegener , being a meteorologist , had proposed tidal forces and centrifugal forces as the main driving mechanisms behind continental drift ; however, these forces were considered far too small to cause continental motion as
2489-633: A section of the bay. Pensacola Bay is bordered by Escambia Bay and East Bay to the north, and Santa Rosa Sound to the east. Pensacola Pass connects the Bay to the Gulf of Mexico. After the War of 1812 , the federal government decided to fortify Pensacola and Pensacola Bay. It built the Navy Yard west of the city in Warrington, starting in 1828 (this was redeveloped in the 20th century as Naval Air Station Pensacola ). It completed construction of Fort Pickens in 1834 at
2620-422: A serious threat to marine life and adjacent coastal wetlands and to the livelihoods of Gulf Coast shrimpers and fishermen. Coast Guard Rear Admiral Sally Brice O'Hare stated that the U.S. government will be "employing booms, skimmers, chemical dispersants and controlled burns" to combat the oil spill. By May 1 the oil spill cleanup efforts were underway but hampered by rough seas and the "tea like" consistency of
2751-407: A solid crust and mantle and a liquid core, but there seemed to be no way that portions of the crust could move around. Many distinguished scientists of the time, such as Harold Jeffreys and Charles Schuchert , were outspoken critics of continental drift. Despite much opposition, the view of continental drift gained support and a lively debate started between "drifters" or "mobilists" (proponents of
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#17328370554122882-478: A static Earth without moving continents up until the major breakthroughs of the early sixties. Two- and three-dimensional imaging of Earth's interior ( seismic tomography ) shows a varying lateral density distribution throughout the mantle. Such density variations can be material (from rock chemistry), mineral (from variations in mineral structures), or thermal (through thermal expansion and contraction from heat energy). The manifestation of this varying lateral density
3013-438: Is mantle convection from buoyancy forces. How mantle convection directly and indirectly relates to plate motion is a matter of ongoing study and discussion in geodynamics. Somehow, this energy must be transferred to the lithosphere for tectonic plates to move. There are essentially two main types of mechanisms that are thought to exist related to the dynamics of the mantle that influence plate motion which are primary (through
3144-495: Is 144 square miles, and it is the fourth largest estuarine system in Florida. Pensacola Bay is formed and protected by Fairpoint Peninsula and the barrier island of Santa Rosa . The Pensacola Bay Bridge crosses the bay, connecting Pensacola to Gulf Breeze on the western end of the peninsula. The Gulf Islands National Seashore includes Santa Rosa Island, and encloses part of the bay. The Gulf Intracoastal Waterway runs through
3275-527: Is based on their modes of formation. Oceanic crust is formed at sea-floor spreading centers. Continental crust is formed through arc volcanism and accretion of terranes through plate tectonic processes. Oceanic crust is denser than continental crust because it has less silicon and more of the heavier elements than continental crust . As a result of this density difference, oceanic crust generally lies below sea level , while continental crust buoyantly projects above sea level. Average oceanic lithosphere
3406-456: Is called a plate boundary . Plate boundaries are where geological events occur, such as earthquakes and the creation of topographic features such as mountains , volcanoes , mid-ocean ridges , and oceanic trenches . The vast majority of the world's active volcanoes occur along plate boundaries, with the Pacific plate's Ring of Fire being the most active and widely known. Some volcanoes occur in
3537-533: Is called the geosynclinal theory . Generally, this was placed in the context of a contracting planet Earth due to heat loss in the course of a relatively short geological time. It was observed as early as 1596 that the opposite coasts of the Atlantic Ocean—or, more precisely, the edges of the continental shelves —have similar shapes and seem to have once fitted together. Since that time many theories were proposed to explain this apparent complementarity, but
3668-490: Is half the typical 40- kilometer (25 mi ) thickness of continental crust. It was at this time that rifting first created a connection to the Pacific Ocean across central Mexico and later eastward to the Atlantic Ocean. This flooded the opening basin to create an enclosed marginal sea. The subsiding transitional crust was blanketed by the widespread deposition of Louann Salt and associated anhydrite evaporites . During
3799-487: Is in motion, presents a problem. The same holds for the African, Eurasian , and Antarctic plates. Gravitational sliding away from mantle doming: According to older theories, one of the driving mechanisms of the plates is the existence of large scale asthenosphere/mantle domes which cause the gravitational sliding of lithosphere plates away from them (see the paragraph on Mantle Mechanisms). This gravitational sliding represents
3930-408: Is invoked as the major driving force, through slab pull along subduction zones. Gravitational sliding away from a spreading ridge is one of the proposed driving forces, it proposes plate motion is driven by the higher elevation of plates at ocean ridges. As oceanic lithosphere is formed at spreading ridges from hot mantle material, it gradually cools and thickens with age (and thus adds distance from
4061-415: Is still advocated to explain the break-up of supercontinents during specific geological epochs. It has followers amongst the scientists involved in the theory of Earth expansion . Another theory is that the mantle flows neither in cells nor large plumes but rather as a series of channels just below Earth's crust, which then provide basal friction to the lithosphere. This theory, called "surge tectonics",
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4192-643: Is that before the late Triassic , the Gulf of Mexico did not exist. Before the Late Triassic, the area consisted of dry land, which included continental crust that now underlies Yucatán , within the middle of the supercontinent Pangaea . This land lay south of a continuous mountain range that extended from north-central Mexico, through the Marathon Uplift in west Texas and the Ouachita Mountains of Oklahoma , and to Alabama where it linked directly to
4323-488: Is to consider the relative rate at which each plate is moving as well as the evidence related to the significance of each process to the overall driving force on the plate. One of the most significant correlations discovered to date is that lithospheric plates attached to downgoing (subducting) plates move much faster than other types of plates. The Pacific plate, for instance, is essentially surrounded by zones of subduction (the so-called Ring of Fire) and moves much faster than
4454-407: Is typically 100 km (62 mi) thick. Its thickness is a function of its age. As time passes, it cools by conducting heat from below, and releasing it raditively into space. The adjacent mantle below is cooled by this process and added to its base. Because it is formed at mid-ocean ridges and spreads outwards, its thickness is therefore a function of its distance from the mid-ocean ridge where it
4585-435: Is used. It asserts that super plumes rise from the deeper mantle and are the drivers or substitutes of the major convection cells. These ideas find their roots in the early 1930s in the works of Beloussov and van Bemmelen , which were initially opposed to plate tectonics and placed the mechanism in a fixed frame of vertical movements. Van Bemmelen later modified the concept in his "Undation Models" and used "Mantle Blisters" as
4716-419: Is widely disputed, and many historians doubt that it took place as described. In his letters, Vespucci described this trip, and once Juan de la Cosa returned to Spain, a famous world map was produced. In 1506 Hernán Cortés took part in the conquest of Hispaniola and Cuba, receiving a large estate of land and indigenous slaves for his effort. In 1510 he accompanied Diego Velázquez de Cuéllar , an aide of
4847-570: The Deepwater Horizon oil platform, located in the Mississippi Canyon about 40 miles (64 km) off the Louisiana coast, suffered a catastrophic explosion ; it sank a day and a half later. It was in the process of being sealed with concrete for temporary abandonment, to avoid environmental problems. Although initial reports indicated that relatively little oil had leaked, by April 24 it
4978-558: The Appalachian Mountains of North America are very similar in structure and lithology . However, his ideas were not taken seriously by many geologists, who pointed out that there was no apparent mechanism for continental drift. Specifically, they did not see how continental rock could plow through the much denser rock that makes up oceanic crust. Wegener could not explain the force that drove continental drift, and his vindication did not come until after his death in 1930. As it
5109-640: The Appalachian Mountains . It was created by the collision of continental plates that formed Pangaea. As interpreted by Roy Van Arsdale and Randel T. Cox, this mountain range was breached in the late Cretaceous by the formation of the Mississippi Embayment . The rifting that created the basin was associated with zones of weakness within Pangaea, including sutures where the Laurentia , South American , and African plates collided to create it. First, there
5240-507: The Bureau of Ocean Energy Management, Regulation and Enforcement ) to help predict the potential impacts of future oil/gas explorations. Since 1979, the specimens have been deposited in the national collections of the National Museum of Natural History. The major environmental threats to the gulf are agricultural runoff and oil drilling . There are 27,000 abandoned oil and gas wells beneath
5371-632: The Mardi Gras sank around the early 19th century about 35 mi (56 km) off the coast of Louisiana in 4,000 feet (1,200 m) of water. She is believed to have been a privateer or trader. The shipwreck, whose real identity remains a mystery, lay forgotten at the bottom of the sea until it was discovered in 2002 by an oilfield inspection crew working for the Okeanos Gas Gathering Company (OGGC). In 2007 an expedition led by Texas A&M University and funded by OGGC under an agreement with
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5502-543: The National Response Center , the oil industry has thousands of minor accidents in the Gulf of Mexico every year. In June 1979, the Ixtoc I oil platform in the Bay of Campeche suffered a blowout leading to a catastrophic explosion, which resulted in a massive oil spill that continued for nine months before the well was finally capped. This was the largest oil spill in the Gulf of Mexico to date. On April 20, 2010,
5633-569: The Old World ; they also had reason to expect that this new land would have gold . All of this encouraged two further expeditions, the first in 1518 under the command of Juan de Grijalva , and the second in 1519 under the command of Hernán Cortés , which led to the Spanish exploration, military invasion, and ultimately settlement and colonization known as the Conquest of Mexico . Hernández did not live to see
5764-422: The chemical subdivision of these same layers into the mantle (comprising both the asthenosphere and the mantle portion of the lithosphere) and the crust: a given piece of mantle may be part of the lithosphere or the asthenosphere at different times depending on its temperature and pressure. The key principle of plate tectonics is that the lithosphere exists as separate and distinct tectonic plates , which ride on
5895-475: 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
6026-724: The fluid-like solid the asthenosphere . Plate motions range from 10 to 40 millimetres per year (0.4 to 1.6 in/year) at the Mid-Atlantic Ridge (about as fast as fingernails grow), to about 160 millimetres per year (6.3 in/year) for the Nazca plate (about as fast as hair grows). Tectonic lithosphere plates consist of lithospheric mantle overlain by one or two types of crustal material: oceanic crust (in older texts called sima from silicon and magnesium ) and continental crust ( sial from silicon and aluminium ). The distinction between oceanic crust and continental crust
6157-473: The lithosphere and asthenosphere . The division is based on differences in mechanical properties and in the method for the transfer of heat . The lithosphere is cooler and more rigid, while the asthenosphere is hotter and flows more easily. In terms of heat transfer, the lithosphere loses heat by conduction , whereas the asthenosphere also transfers heat by convection and has a nearly adiabatic temperature gradient. This division should not be confused with
6288-415: The Atlantic Ocean, the gulf experiences very small tidal ranges . The size of the gulf basin is approximately 1.6 million km (620,000 sq mi). Almost half of the basin consists of shallow continental shelf waters. The volume of water in the basin is roughly 2.4 × 10 cubic kilometers (5.8 × 10 cubic miles). The gulf is one of the most important offshore petroleum production regions in
6419-590: The Earth's rotation and the Moon as main driving forces for the plates. The vector of a plate's motion is a function of all the forces acting on the plate; however, therein lies the problem regarding the degree to which each process contributes to the overall motion of each tectonic plate. The diversity of geodynamic settings and the properties of each plate result from the impact of the various processes actively driving each individual plate. One method of dealing with this problem
6550-588: The French commandant. The Gulf of Mexico's eastern, northern, and northwestern shores lie along the US states of Florida, Alabama, Mississippi, Louisiana, and Texas. The US portion of the coastline spans 1,680 miles (2,700 km), receiving water from 33 major rivers that drain 31 states and 2 Canadian provinces. The southwestern and southern shores lie along the Mexican states of Tamaulipas, Veracruz, Tabasco, Campeche, Yucatán, and
6681-506: The Gulf of Mexico. Instead, the Spanish sailed into the Caribbean around Cuba and Hispaniola . The first alleged European exploration of the Gulf of Mexico was by Amerigo Vespucci in 1497. Vespucci is purported to have followed the coastal land mass of Central America before returning to the Atlantic Ocean via the Straits of Florida between Florida and Cuba. However, this first voyage of 1497
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#17328370554126812-669: The Minerals Management Service (now BOEM ) was launched to undertake the deepest scientific archaeological excavation ever attempted at that time to study the site on the seafloor and recover artifacts for eventual public display in the Louisiana State Museum . As part of the project educational outreach Nautilus Productions in partnership with BOEM, Texas A&M University, the Florida Public Archaeology Network and Veolia Environmental produced
6943-553: The Northward along this meridian to the latitude of the South point of the Dry Tortugas (24°35'N), along this parallel Eastward to Rebecca Shoal (82°35'W) thence through the shoals and Florida Keys to the mainland at the eastern end of Florida Bay and all the narrow waters between the Dry Tortugas and the mainland being considered to be within the Gulf. The consensus among geologists
7074-475: The Padre Island treasure. This loss, in combination with other ship disasters around the Gulf of Mexico, gave rise to a plan for establishing a settlement on the northern Gulf Coast to protect shipping and more quickly rescue castaways. As a result, the expedition of Tristán de Luna y Arellano was sent and landed at Pensacola Bay on August 15, 1559. On December 11, 1526, Charles V granted Pánfilo de Narváez
7205-526: The Spanish; he sailed from there to Mobile Bay and explored Massacre Island, later renamed Dauphin Island . He cast anchor between Cat Island and Ship Island ; and on February 13 he went to the mainland, Biloxi , with his brother Jean-Baptiste Le Moyne de Bienville . On May 1 he completed Fort Maurepas on the northeast side of the Bay of Biloxi. On May 4 d'Iberville sailed for France leaving his teenage brother, Jean-Baptiste Le Moyne , as second in command to
7336-508: The United States ; on the southwest and south by the Mexican states of Tamaulipas , Veracruz , Tabasco , Campeche , Yucatán , and Quintana Roo ; and on the southeast by Cuba . The Southern U.S. states of Texas , Louisiana , Mississippi , Alabama , and Florida , which border the gulf on the north, are often referred to as the " Third Coast " of the United States (in addition to its Atlantic and Pacific coasts). The Gulf of Mexico took shape approximately 300 million years ago as
7467-530: The United States of America and the Republic of Cuba, of December 16, 1977. Mexico and United States: Treaty to resolve pending boundary differences and maintain the Rio Grande and Colorado River as the international boundary, of November 23, 1970; Treaty on maritime boundaries between the United States of America and the United Mexican States (Caribbean Sea and Pacific Ocean), of May 4, 1978, and treaty on
7598-601: The United States, in accordance with Mexico's domestic legislation. On March 13, 2009, the CLCS accepted Mexico's arguments for extending its continental shelf up to 350 nautical miles (650 km; 400 mi) into the Western Polygon. Since this would extend Mexico's continental shelf well into territory claimed by the United States, however, Mexico and the U.S. would need to enter a bilateral agreement based on international law that delimits their respective claims. A ship now called
7729-533: The actual motions of the Pacific plate and other plates associated with the East Pacific Rise do not correlate mainly with either slab pull or slab push, but rather with a mantle convection upwelling whose horizontal spreading along the bases of the various plates drives them along via viscosity-related traction forces. The driving forces of plate motion continue to be active subjects of on-going research within geophysics and tectonophysics . The development of
7860-478: The assumption of a solid Earth made these various proposals difficult to accept. The discovery of radioactivity and its associated heating properties in 1895 prompted a re-examination of the apparent age of Earth . This had previously been estimated by its cooling rate under the assumption that Earth's surface radiated like a black body . Those calculations had implied that, even if it started at red heat , Earth would have dropped to its present temperature in
7991-399: The asthenosphere. This theory was launched by Arthur Holmes and some forerunners in the 1930s and was immediately recognized as the solution for the acceptance of the theory as originally discussed in the papers of Alfred Wegener in the early years of the 20th century. However, despite its acceptance, it was long debated in the scientific community because the leading theory still envisaged
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#17328370554128122-764: The attack. One officer, nine crewmen and 15 passengers were lost. The passengers aboard Robert E. Lee were primarily survivors of previous torpedo attacks by German U-boats. The wreck's location was discovered during the C & C Marine survey that located the U-166 . In 2001 the wreck of U-166 was found in 5,000 feet (1,500 m) of water, less than two miles (3.2 km) from where it had attacked Robert E. Lee . Various biota include chemosynthetic communities near cold seeps and non chemosynthetic communities such as bacteria and other micro- benthos , meiofauna , macrofauna , and megafauna (larger organisms such as crabs , sea pens , crinoids , demersal fish , cetaceans , and
8253-469: The base of the lithosphere. Slab pull is therefore most widely thought to be the greatest force acting on the plates. In this understanding, plate motion is mostly driven by the weight of cold, dense plates sinking into the mantle at trenches. Recent models indicate that trench suction plays an important role as well. However, the fact that the North American plate is nowhere being subducted, although it
8384-553: The basin expanded and deepened. Later, loading of the crust within the basin and adjacent coastal plain by the accumulation of kilometers of sediments during the rest of the Mesozoic and all of the Cenozoic further depressed the underlying crust to its current position about 10–20 km (6.2–12.4 mi) below sea level. Particularly during the Cenozoic, a time of relative stability for
8515-421: The basin experienced a period of cooling and subsidence of the crust underlying it. The subsidence was the result of a combination of crustal stretching, cooling, and loading. Initially, the combination of crustal stretching and cooling caused about 5–7 km (3.1–4.3 mi) of tectonic subsidence of the central thin transitional and oceanic crust. Because subsidence occurred faster than sediment could fill it,
8646-495: The bathymetry of the deep ocean floors and the nature of the oceanic crust such as magnetic properties and, more generally, with the development of marine geology which gave evidence for the association of seafloor spreading along the mid-oceanic ridges and magnetic field reversals , published between 1959 and 1963 by Heezen, Dietz, Hess, Mason, Vine & Matthews, and Morley. Simultaneous advances in early seismic imaging techniques in and around Wadati–Benioff zones along
8777-421: 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
8908-432: The coastal zones, thick clastic wedges built out the continental shelf along the northwestern and northern margins of the basin. To the east, the stable Florida Platform was not covered by the sea until the latest Jurassic or the beginning of Cretaceous time. The Yucatán Platform was emergent until the mid-Cretaceous. After both platforms were submerged, the formation of carbonates and evaporites has characterized
9039-413: The concept was of continents plowing through oceanic crust. Therefore, Wegener later changed his position and asserted that convection currents are the main driving force of plate tectonics in the last edition of his book in 1929. However, in the plate tectonics context (accepted since the seafloor spreading proposals of Heezen, Hess, Dietz, Morley, Vine, and Matthews (see below) during the early 1960s),
9170-418: The continuation of his work: he died in 1517, the year of his expedition, as the result of the injuries and the extreme thirst suffered during the voyage, and disappointed in the knowledge that Diego Velázquez had given precedence to Grijalva as the captain of the next expedition to Yucatán. In 1523, a treasure ship was wrecked en route at Padre Island , Texas. When word of the disaster reached Mexico City,
9301-415: The deep mantle at subduction zones, providing most of the driving force for plate movement. The weakness of the asthenosphere allows the tectonic plates to move easily towards a subduction zone. For much of the first quarter of the 20th century, the leading theory of the driving force behind tectonic plate motions envisaged large scale convection currents in the upper mantle, which can be transmitted through
9432-644: The delimitation of the continental shelf in the western Gulf of Mexico beyond 200 nautical miles (370 km; 230 mi), of June 9, 2000. On December 13, 2007, Mexico submitted information to the Commission on the Limits of the Continental Shelf (CLCS) regarding the extension of Mexico's continental shelf beyond 200 nautical miles. Mexico sought an extension of its continental shelf in the Western Polygon based on international law, UNCLOS, and bilateral treaties with
9563-401: 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; when a hurricane passes over the water temperature may drop but it soon rebounds and becomes capable of supporting another tropical storm. From 1970 to 2020, surface temperatures warmed at approximately twice
9694-530: The discussions treated in this section) or proposed as minor modulations within the overall plate tectonics model. In 1973, George W. Moore of the USGS and R. C. Bostrom presented evidence for a general westward drift of Earth's lithosphere with respect to the mantle, based on the steepness of the subduction zones (shallow dipping towards the east, steeply dipping towards the west). They concluded that tidal forces (the tidal lag or "friction") caused by Earth's rotation and
9825-466: The driving force for horizontal movements, invoking gravitational forces away from the regional crustal doming. The theories find resonance in the modern theories which envisage hot spots or mantle plumes which remain fixed and are overridden by oceanic and continental lithosphere plates over time and leave their traces in the geological record (though these phenomena are not invoked as real driving mechanisms, but rather as modulators). The mechanism
9956-472: The explosion destroyed the #3 hold, vented through the B and C decks and damaged the engines, the radio compartment and the steering gear. After the attack she was under escort by USS PC-566 , captained by Lieutenant Commander Herbert G. Claudius, en route to New Orleans . PC-566 began dropping depth charges on a sonar contact, sinking U-166 . The badly damaged Robert E. Lee first listed to port then to starboard and finally sank within about 15 minutes of
10087-542: The extinct Caribbean monk seal ) are living in the Gulf of Mexico. Recently, resident Bryde's whales within the gulf were classified as an endemic, unique subspecies and making them as one of the most endangered whales in the world. The Gulf of Mexico yields more fish, shrimp, and shellfish annually than the south and mid-Atlantic , Chesapeake , and New England areas combined. The Smithsonian Institution Gulf of Mexico holdings are expected to provide an important baseline of understanding for future scientific studies on
10218-473: The final one in 1936), he noted how the east coast of South America and the west coast of Africa looked as if they were once attached. Wegener was not the first to note this ( Abraham Ortelius , Antonio Snider-Pellegrini , Eduard Suess , Roberto Mantovani and Frank Bursley Taylor preceded him just to mention a few), but he was the first to marshal significant fossil and paleo-topographical and climatological evidence to support this simple observation (and
10349-691: The forces acting upon it by the Moon are a driving force for plate tectonics. As Earth spins eastward beneath the Moon, the Moon's gravity ever so slightly pulls Earth's surface layer back westward, just as proposed by Alfred Wegener (see above). Since 1990 this theory is mainly advocated by Doglioni and co-workers ( Doglioni 1990 ), such as in a more recent 2006 study, where scientists reviewed and advocated these ideas. It has been suggested in Lovett (2006) that this observation may also explain why Venus and Mars have no plate tectonics, as Venus has no moon and Mars' moons are too small to have significant tidal effects on
10480-588: The geographical latitudinal and longitudinal grid of Earth itself. These systematic relations studies in the second half of the nineteenth century and the first half of the twentieth century underline exactly the opposite: that the plates had not moved in time, that the deformation grid was fixed with respect to Earth's equator and axis, and that gravitational driving forces were generally acting vertically and caused only local horizontal movements (the so-called pre-plate tectonic, "fixist theories"). Later studies (discussed below on this page), therefore, invoked many of
10611-535: The geologic history of these two stable areas. Most of the basin was rimmed during the early Cretaceous by carbonate platforms, and its western flank was involved during the latest Cretaceous and early Paleogene periods in a compressive deformation episode, the Laramide Orogeny , which created the Sierra Madre Oriental of eastern Mexico. In 2014, Erik Cordes of Temple University and others discovered
10742-570: The governor of Hispaniola, in his expedition to conquer Cuba. In 1518 Velázquez put him in command of an expedition to explore and secure the interior of Mexico for colonization. In 1517 Francisco Hernández de Córdoba discovered the Yucatán Peninsula. This was the first European encounter with an advanced civilization in the Americas , with solidly built buildings and a complex social organization which they recognized as being comparable to those of
10873-616: The greatest depth of 12,467 feet in the Sigsbee Deep . Seven main areas are given as: As early as the Maya civilization , the Gulf of Mexico was used as a trade route off the coast of the Yucatán Peninsula and present-day Veracruz . Although the Spanish voyage of Christopher Columbus was credited with the discovery of the Americas by Europeans, the ships in his four voyages did not reach
11004-493: The gulf's first such study estimated concentrations that rival the highest globally reported. 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 and southern Florida coast, from the Florida Keys to north of Pasco County, Florida . The gulf contains
11135-506: The gulf. These have generally not been checked for potential environmental problems. In 1973 the United States Environmental Protection Agency prohibited the dumping of undiluted chemical waste by manufacturing interests into the gulf, and the military confessed to similar behavior in waters off Horn Island . Microplastics within semi-enclosed seas like the gulf have been reported in high concentrations, and
11266-480: The impact of the Deepwater Horizon oil spill . In Congressional testimony, Dr. Jonathan Coddington, associate director of Research and Collections at the Smithsonian's National Museum of Natural History , provides a detailed overview of the Gulf collections and their sources which Museum staff have made available on an online map. The samples were collected for years by the former Minerals Management Service (renamed
11397-658: The interiors of plates, and these have been variously attributed to internal plate deformation and to mantle plumes. Tectonic plates may include continental crust or oceanic crust, or both. For example, the African plate includes the continent and parts of the floor of the Atlantic and Indian Oceans. Some pieces of oceanic crust, known as ophiolites , failed to be subducted under continental crust at destructive plate boundaries; instead these oceanic crustal fragments were pushed upward and were preserved within continental crust. Three types of plate boundaries exist, characterized by
11528-412: The large scale convection cells) or secondary. The secondary mechanisms view plate motion driven by friction between the convection currents in the asthenosphere and the more rigid overlying lithosphere. This is due to the inflow of mantle material related to the downward pull on plates in subduction zones at ocean trenches. Slab pull may occur in a geodynamic setting where basal tractions continue to act on
11659-473: The late Jurassic, continued rifting widened the basin and progressed to the point that seafloor spreading and formation of oceanic crust occurred. At this point, sufficient circulation with the Atlantic Ocean was established that the deposition of Louann Salt ceased. Seafloor spreading stopped at the end of the Jurassic, about 145–150 million years ago. During the late Jurassic through early Cretaceous,
11790-421: The lithosphere before it dives underneath an adjacent plate, producing a clear topographical feature that can offset, or at least affect, the influence of topographical ocean ridges. Mantle plumes and hot spots are also postulated to impinge on the underside of tectonic plates. Slab pull : Scientific opinion is that the asthenosphere is insufficiently competent or rigid to directly cause motion by friction along
11921-403: The lower mantle, there is a slight westward component in the motions of all the plates. They demonstrated though that the westward drift, seen only for the past 30 Ma, is attributed to the increased dominance of the steadily growing and accelerating Pacific plate. The debate is still open, and a recent paper by Hofmeister et al. (2022) revived the idea advocating again the interaction between
12052-405: The many geographical, geological, and biological continuities between continents. In 1912, the meteorologist Alfred Wegener described what he called continental drift, an idea that culminated fifty years later in the modern theory of plate tectonics. Wegener expanded his theory in his 1915 book The Origin of Continents and Oceans . Starting from the idea (also expressed by his forerunners) that
12183-429: The matching of the rock formations along these edges. Confirmation of their previous contiguous nature also came from the fossil plants Glossopteris and Gangamopteris , and the therapsid or mammal-like reptile Lystrosaurus , all widely distributed over South America, Africa, Antarctica, India, and Australia. The evidence for such an erstwhile joining of these continents was patent to field geologists working in
12314-512: The motion picture of the Atlantic region", processes that anticipated seafloor spreading and subduction . One of the first pieces of geophysical evidence that was used to support the movement of lithospheric plates came from paleomagnetism . This is based on the fact that rocks of different ages show a variable magnetic field direction, evidenced by studies since the mid–nineteenth century. The magnetic north and south poles reverse through time, and, especially important in paleotectonic studies,
12445-438: The motion. At a subduction zone the relatively cold, dense oceanic crust sinks down into the mantle, forming the downward convecting limb of a mantle cell , which is the strongest driver of plate motion. The relative importance and interaction of other proposed factors such as active convection, upwelling inside the mantle, and tidal drag of the Moon is still the subject of debate. The outer layers of Earth are divided into
12576-466: The north pole, and each continent, in fact, shows its own "polar wander path". During the late 1950s, it was successfully shown on two occasions that these data could show the validity of continental drift: by Keith Runcorn in a paper in 1956, and by Warren Carey in a symposium held in March 1956. The second piece of evidence in support of continental drift came during the late 1950s and early 60s from data on
12707-453: 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 Gulf of Mexico is an excellent example of a passive margin . The continental shelf is quite wide at most points along
12838-416: The northernmost tip of Quintana Roo. The Mexican coastline spans 1,743 miles (2,805 km). On its southeast quadrant, the gulf is 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
12969-407: The oceanic crust is suggested to be in motion with the continents which caused the proposals related to Earth rotation to be reconsidered. In more recent literature, these driving forces are: Forces that are small and generally negligible are: For these mechanisms to be overall valid, systematic relationships should exist all over the globe between the orientation and kinematics of deformation and
13100-437: The oceanic lithosphere and the thicker continental lithosphere, each topped by its own kind of crust. Along convergent plate boundaries , the process of subduction carries the edge of one plate down under the other plate and into the mantle . This process reduces the total surface area (crust) of the Earth. The lost surface is balanced by the formation of new oceanic crust along divergent margins by seafloor spreading, keeping
13231-412: The oil. Cleanup operations were resumed after conditions became favorable. On May 27 the USGS had revised the estimate of the leak from 5,000 barrels per day (790 m /d) to 12,000–19,000 barrels per day (3,000 m /d) an increase from earlier estimates. On July 15 BP announced that the leak had stopped for the first time in 88 days. In July BP reached an $ 18.7bn settlement with the U.S. government,
13362-565: The pass. 30°22′06″N 87°12′03″W / 30.36833°N 87.20083°W / 30.36833; -87.20083 Gulf of Mexico The Gulf of Mexico ( Spanish : Golfo de México ) is an ocean basin and a marginal sea of the Atlantic Ocean , mostly surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of
13493-603: The past three decades in the region. According to the September 11, 2006 issue of The Tampa Tribune , earthquake tremors were last felt in Florida in 1952, recorded in Quincy , 20 miles (32 km) northwest of Tallahassee . Cuba and Mexico: Exchange of notes constituting an agreement on the delimitation of the exclusive economic zone of Mexico in the sector adjacent to Cuban maritime areas (with map), of July 26, 1976. Cuba and United States: Maritime boundary agreement between
13624-407: The planet. In a paper by it was suggested that, on the other hand, it can easily be observed that many plates are moving north and eastward, and that the dominantly westward motion of the Pacific Ocean basins derives simply from the eastward bias of the Pacific spreading center (which is not a predicted manifestation of such lunar forces). In the same paper the authors admit, however, that relative to
13755-399: The plate as it dives into the mantle (although perhaps to a greater extent acting on both the under and upper side of the slab). Furthermore, slabs that are broken off and sink into the mantle can cause viscous mantle forces driving plates through slab suction. In the theory of plume tectonics followed by numerous researchers during the 1990s, a modified concept of mantle convection currents
13886-426: The plates of the Atlantic basin, which are attached (perhaps one could say 'welded') to adjacent continents instead of subducting plates. It is thus thought that forces associated with the downgoing plate (slab pull and slab suction) are the driving forces which determine the motion of plates, except for those plates which are not being subducted. This view however has been contradicted by a recent study which found that
14017-408: The present continents once formed a single land mass (later called Pangaea ), Wegener suggested that these separated and drifted apart, likening them to "icebergs" of low density sial floating on a sea of denser sima . Supporting evidence for the idea came from the dove-tailing outlines of South America's east coast and Africa's west coast Antonio Snider-Pellegrini had drawn on his maps, and from
14148-469: The rate observed for the global ocean surface. The gulf is considered aseismic ; however, mild tremors have been recorded throughout history (usually 5.0 or less on the Richter magnitude scale ). Earthquakes may be caused by interactions between sediment loading on the sea floor and adjustment by the crust. On September 10, 2006, the U.S. Geological Survey National Earthquake Information Center reported that
14279-459: The relationships recognized during this pre-plate tectonics period to support their theories (see reviews of these various mechanisms related to Earth rotation the work of van Dijk and collaborators). Of the many forces discussed above, tidal force is still highly debated and defended as a possible principal driving force of plate tectonics. The other forces are only used in global geodynamic models not using plate tectonics concepts (therefore beyond
14410-428: The relative position of the magnetic north pole varies through time. Initially, during the first half of the twentieth century, the latter phenomenon was explained by introducing what was called "polar wander" (see apparent polar wander ) (i.e., it was assumed that the north pole location had been shifting through time). An alternative explanation, though, was that the continents had moved (shifted and rotated) relative to
14541-399: The ridge). Cool oceanic lithosphere is significantly denser than the hot mantle material from which it is derived and so with increasing thickness it gradually subsides into the mantle to compensate the greater load. The result is a slight lateral incline with increased distance from the ridge axis. This force is regarded as a secondary force and is often referred to as " ridge push ". This is
14672-614: The rigid outer shell of the planet including the crust and upper mantle , is fractured into seven or eight major plates (depending on how they are defined) and many minor plates or "platelets". Where the plates meet, their relative motion determines the type of plate boundary (or fault ): convergent , divergent , or transform . The relative movement of the plates typically ranges from zero to 10 cm annually. Faults tend to be geologically active, experiencing earthquakes , volcanic activity , mountain-building , and oceanic trench formation. Tectonic plates are composed of
14803-402: The sea about 97 miles (156 km) south of Port Fourchon , Louisiana , according to the U.S. Bureau of Safety and Environmental Enforcement. Plate tectonics Plate tectonics (from Latin tectonicus , from Ancient Greek τεκτονικός ( tektonikós ) 'pertaining to building') is the scientific theory that Earth 's lithosphere comprises
14934-486: The southern hemisphere. The South African Alex du Toit put together a mass of such information in his 1937 publication Our Wandering Continents , and went further than Wegener in recognising the strong links between the Gondwana fragments. Wegener's work was initially not widely accepted, in part due to a lack of detailed evidence but mostly because of the lack of a reasonable physically supported mechanism. Earth might have
15065-409: The states of Alabama, Florida, Louisiana, Mississippi and Texas, as well as 400 local authorities. As of 2015 BP's cost for the clean-up, environmental and economic damages and penalties has reached $ 54bn. On May 12, 2016, a release of oil from subsea infrastructure on Shell's Brutus oil rig released 2,100 barrels of oil. This leak created a visible 2 by 13 miles (3.2 by 20.9 km) oil slick in
15196-470: The theory of plate tectonics was the scientific and cultural change which occurred during a period of 50 years of scientific debate. The event of the acceptance itself was a paradigm shift and can therefore be classified as a scientific revolution, now described as the Plate Tectonics Revolution . Around the start of the twentieth century, various theorists unsuccessfully attempted to explain
15327-502: The theory) and "fixists" (opponents). During the 1920s, 1930s and 1940s, the former reached important milestones proposing that convection currents might have driven the plate movements, and that spreading may have occurred below the sea within the oceanic crust. Concepts close to the elements of plate tectonics were proposed by geophysicists and geologists (both fixists and mobilists) like Vening-Meinesz, Holmes, and Umbgrove. In 1941, Otto Ampferer described, in his publication "Thoughts on
15458-476: The total surface area constant in a tectonic "conveyor belt". Tectonic plates are relatively rigid and float across the ductile asthenosphere beneath. Lateral density variations in the mantle result in convection currents, the slow creeping motion of Earth's solid mantle. At a seafloor spreading ridge , plates move away from the ridge, which is a topographic high, and the newly formed crust cools as it moves away, increasing its density and contributing to
15589-429: The trenches bounding many continental margins, together with many other geophysical (e.g., gravimetric) and geological observations, showed how the oceanic crust could disappear into the mantle, providing the mechanism to balance the extension of the ocean basins with shortening along its margins. All this evidence, both from the ocean floor and from the continental margins, made it clear around 1965 that continental drift
15720-490: The viceroy requested a rescue fleet and sent Ángel de Villafañe from Mexico City, marching overland to find the treasure-laden vessels. Villafañe traveled to Pánuco and hired a ship to transport him to the site, which had already been visited from that community. He arrived in time to greet García de Escalante Alvarado (a nephew of Pedro de Alvarado ), commander of the salvage operation, when Alvarado arrived by sea on July 22, 1554. The team labored until September 12 to salvage
15851-467: The way the plates move relative to each other. They are associated with different types of surface phenomena. The different types of plate boundaries are: Tectonic plates are able to move because of the relative density of oceanic lithosphere and the relative weakness of the asthenosphere . Dissipation of heat from the mantle is the original source of the energy required to drive plate tectonics through convection or large scale upwelling and doming. As
15982-537: The western end of Santa Rosa Island; completed Fort McRee in 1839, and completed redesign and expansion of Fort Barrancas in 1844, to add to defenses. Following the Deepwater Horizon oil spill (called the "Gulf oil spill"), the government and BP planned to close the entrance to Pensacola Pass with a floating barrier system in June 2010, to control tidal flow of oil entering from the Gulf of Mexico. The daily high tide
16113-508: The world, making up one-sixth of the United States' total production. The International Hydrographic Organization defines the southeast limit of the Gulf of Mexico as: A line joining Cape Catoche Light ( 21°37′N 87°04′W / 21.617°N 87.067°W / 21.617; -87.067 ) with the Light on Cape San Antonio in Cuba, through this island to the meridian of 83°W and to
16244-434: Was a late Triassic–early Jurassic phase of rifting during which rift valleys formed and filled with continental red beds . Second, as rifting progressed through early and middle Jurassic times, the continental crust was stretched and thinned. This thinning created a broad zone of transitional crust, which displays modest and uneven thinning with block faulting and a broad zone of uniformly thinned transitional crust, which
16375-443: Was causing oil-contaminated water to enter Pensacola Bay. Such a barrier system is designed to allow boats to travel through Pensacola Pass during the outflowing tide, but to close during the rising tide. The booming plan was never carried out. The Pass was only boomed for a day due to strong currents which broke the boom. No other plan was in place in areas of less current nor was there a plan to trap incoming oil. Oil product entered
16506-462: Was claimed by BP that approximately 1,000 barrels (160 m ) of oil per day were issuing from the wellhead , about 1-mile (1.6 km) below the surface on the ocean floor. On April 29, the U.S. government revealed that approximately 5,000 barrels (790 m ) per day, five times the original estimate, were pouring into the gulf from the wellhead. The resulting oil slick quickly expanded to cover hundreds of square miles of ocean surface, posing
16637-531: Was feasible. The theory of plate tectonics was defined in a series of papers between 1965 and 1967. The theory revolutionized the Earth sciences, explaining a diverse range of geological phenomena and their implications in other studies such as paleogeography and paleobiology . In the late 19th and early 20th centuries, geologists assumed that Earth's major features were fixed, and that most geologic features such as basin development and mountain ranges could be explained by vertical crustal movement, described in what
16768-599: Was formed. For a typical distance that oceanic lithosphere must travel before being subducted, the thickness varies from about 6 km (4 mi) thick at mid-ocean ridges to greater than 100 km (62 mi) at subduction zones. For shorter or longer distances, the subduction zone, and therefore also the mean, thickness becomes smaller or larger, respectively. Continental lithosphere is typically about 200 km (120 mi) thick, though this varies considerably between basins, mountain ranges, and stable cratonic interiors of continents. The location where two plates meet
16899-424: Was observed early that although granite existed on continents, seafloor seemed to be composed of denser basalt , the prevailing concept during the first half of the twentieth century was that there were two types of crust, named "sial" (continental type crust) and "sima" (oceanic type crust). Furthermore, it was supposed that a static shell of strata was present under the continents. It therefore looked apparent that
17030-443: Was popularized during the 1980s and 1990s. Recent research, based on three-dimensional computer modelling, suggests that plate geometry is governed by a feedback between mantle convection patterns and the strength of the lithosphere. Forces related to gravity are invoked as secondary phenomena within the framework of a more general driving mechanism such as the various forms of mantle dynamics described above. In modern views, gravity
17161-560: Was supported in this by researchers such as Alex du Toit ). Furthermore, when the rock strata of the margins of separate continents are very similar it suggests that these rocks were formed in the same way, implying that they were joined initially. For instance, parts of Scotland and Ireland contain rocks very similar to those found in Newfoundland and New Brunswick . Furthermore, the Caledonian Mountains of Europe and parts of
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