The Gulf Coastal Plain extends around the Gulf of Mexico in the Southern United States and eastern Mexico.
The Gulf of Mexico is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. 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 U.S. states of Texas, Louisiana, Mississippi, Alabama, and Florida border the Gulf on the north, which are often referred to as the "Third Coast", in comparison with the U.S. Atlantic and Pacific coasts.
The southern United States, also known as the American South, Dixie, Dixieland, or simply the South, is a region of the United States of America. It is located between the Atlantic Ocean and the western United States, with the midwestern United States and northeastern United States to its north and the Gulf of Mexico and Mexico to its south.
Mexico, officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatemala, Belize, and the Caribbean Sea; and to the east by the Gulf of Mexico. Covering almost 2,000,000 square kilometres (770,000 sq mi), the nation is the fifth largest country in the Americas by total area and the 13th largest independent state in the world. With an estimated population of over 120 million people, the country is the eleventh most populous state and the most populous Spanish-speaking state in the world, while being the second most populous nation in Latin America after Brazil. Mexico is a federation comprising 31 states and Mexico City, a special federal entity that is also the capital city and its most populous city. Other metropolises in the state include Guadalajara, Monterrey, Puebla, Toluca, Tijuana and León.
The plain reaches from the Florida Panhandle, southwest Georgia, the southern two-thirds of Alabama, over most of Mississippi, western Tennessee and Kentucky, into southern Illinois, the Missouri Bootheel, eastern and southern Arkansas, all of Louisiana, the southeast corner of Oklahoma, and easternmost Texas in the United States.It continues along the Gulf in northeastern and eastern Mexico, through Tamaulipas and Veracruz to Tabasco and the Yucatán Peninsula on the Bay of Campeche.
In geography, a plain is a flat, sweeping landmass that generally does not change much in elevation. Plains occur as lowlands along the bottoms of valleys or on the doorsteps of mountains, as coastal plains, and as plateaus or uplands.
The Florida Panhandle, an informal, unofficial term for the northwestern part of the U.S. state of Florida, is a strip of land roughly 200 miles (320 km) long and 50 to 100 miles wide, lying between Alabama on the north and the west, Georgia on the north, and the Gulf of Mexico to the south. Its eastern boundary is arbitrarily defined. The terms West Florida and Northwest Florida are today generally synonymous with the Panhandle, although historically West Florida was the name of a British colony (1763–1783), later a Spanish colony (1783–1821), both of which included modern-day Florida west of the Apalachicola River as well as portions of what are now Alabama, Mississippi, and Louisiana.
Georgia is a state in the Southeastern United States. It began as a British colony in 1733, the last and southernmost of the original Thirteen Colonies to be established. Named after King George II of Great Britain, the Province of Georgia covered the area from South Carolina south to Spanish Florida and west to French Louisiana at the Mississippi River. Georgia was the fourth state to ratify the United States Constitution, on January 2, 1788. In 1802–1804, western Georgia was split to the Mississippi Territory, which later split to form Alabama with part of former West Florida in 1819. Georgia declared its secession from the Union on January 19, 1861, and was one of the original seven Confederate states. It was the last state to be restored to the Union, on July 15, 1870. Georgia is the 24th largest and the 8th most populous of the 50 United States. From 2007 to 2008, 14 of Georgia's counties ranked among the nation's 100 fastest-growing, second only to Texas. Georgia is known as the Peach State and the Empire State of the South. Atlanta, the state's capital and most populous city, has been named a global city. Atlanta's metropolitan area contains about 55% of the population of the entire state.
The Gulf Coastal Plain's southern boundary is the Gulf of Mexico in the U.S. and the Sierra Madre de Chiapas in Mexico. On the north, it extends to the Ouachita Highlands of the Interior Low Plateaus and the southern Appalachian Mountains. Its northernmost extent is along the Mississippi embayment (Mississippi Alluvial Valley) as far north as the southern tip of Illinois.To the east the Gulf coastal plain meets the South Atlantic Coastal Plain in southern Georgia along the basin divide between the rivers flowing into the Gulf and those flowing to the Atlantic and south along the Apalachicola River through the Florida panhandle. The flat to rolling topography is broken by many streams, river riparian areas, and marsh wetlands. The Gulf Coastal Plain also extends into southern Mexico and up to the northern west coast states of the US.
The Sierra Madre de Chiapas is a major mountain range in Central America. The Sierra Madre de Chiapas is part of the American Cordillera, a chain of mountain ranges (cordillera) that consists of an almost continuous sequence of mountain ranges that form the western "backbone" of North America, Central America, and South America.
The Ouachita Mountains, simply referred to as the Ouachitas, are a mountain range in western Arkansas and southeastern Oklahoma. They are formed by a thick succession of highly deformed Paleozoic strata constituting the Ouachita Fold and Thrust Belt, one of the important orogenic belts of North America. The Ouachitas continue in the subsurface to the southeast where they make a poorly understood connection with the Appalachians and to the southwest where they join with the Marathon area of West Texas. Together with the Ozark Plateaus, the Ouachitas form the U.S. Interior Highlands. The highest natural point is Mount Magazine at 2,753 feet.
The Appalachian Mountains, often called the Appalachians, are a system of mountains in eastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period. They once reached elevations similar to those of the Alps and the Rocky Mountains before experiencing natural erosion. The Appalachian chain is a barrier to east–west travel, as it forms a series of alternating ridgelines and valleys oriented in opposition to most highways and railroads running east–west.
The Gulf Coastal Plain is a westward extension of the Atlantic Coastal Plain around the Gulf of Mexico. It is only the lower, seaward part of this region that deserves the name of plain, for there alone is the surface unbroken by hills or valleys. The inner part, initially a plain, has been maturely dissected into an elaborate complex of hills and valleys, usually of increasing altitude and relief as one passes inland. The Gulf Plain features not found in the Atlantic coastal plain are:
A peninsula is a landform surrounded by water on the majority of its border while being connected to a mainland from which it extends. The surrounding water is usually understood to be continuous, though not necessarily named as a single body of water. Peninsulas are not always named as such; one can also be a headland, cape, island promontory, bill, point, or spit. A point is generally considered a tapering piece of land projecting into a body of water that is less prominent than a cape. A river which courses through a very tight meander is also sometimes said to form a "peninsula" within the loop of water. In English, the plural versions of peninsula are peninsulas and, less commonly, peninsulae.
Soil is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Earth's body of soil, called the pedosphere, has four important functions:
Alabama is a state in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east, Florida and the Gulf of Mexico to the south, and Mississippi to the west. Alabama is the 30th largest by area and the 24th-most populous of the U.S. states. With a total of 1,500 miles (2,400 km) of inland waterways, Alabama has among the most of any state.
A broad, low crustal arch extends southward at the junction of the Atlantic and Gulf coastal plains. The emerged half of the arch, constitutes the visible lowland peninsula of Florida. The submerged half extends westward under the shallow Florida overlapping waters of the Gulf of Mexico. The northern part of the peninsula is composed largely of a weak limestone.
Limestone is a carbonate sedimentary rock that is often composed of the skeletal fragments of marine organisms such as coral, foraminifera, and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3). A closely related rock is dolostone, which contains a high percentage of the mineral dolomite, CaMg(CO3)2. In fact, in old USGS publications, dolostone was referred to as magnesian limestone, a term now reserved for magnesium-deficient dolostones or magnesium-rich limestones.
Here, much of the lowland drainage is underground forming many sinkholes (swallowholes). Many small lakes in the lowland appear to owe their basins to the solution of the limestones. Valuable phosphate deposits occur in certain districts. The southern part of the state includes the Everglades, a large area of low, flat, marshy land, overgrown with tall reedy grass.
The eastern coast is fringed by long-stretching sand reefs, enclosing lagoons so narrow and continuous that they are popularly called rivers. At the southern end of the peninsula is a series of coral islands, known as the Florida Keys. They appear to be due to the forward growth of corals and other lime-secreting organisms towards the strong current of the Gulf Stream from which they obtain their food. The western coast has fewer, shorter off-shore reefs. Much of it is of minutely irregular outline.
A typical example of a belted coastal plain is found in Alabama and the adjacent part of Mississippi. The plain is here about 150 mi (240 km) wide. The basal formation is chiefly a weak limestone, which has been stripped from its original Alabama innermost extension and worn down to a flat inner lowland of rich black soil, thus gaining the name of the black belt.
The lowland is enclosed by an upland or escarpment, known as Chunnenugga Ridge, sustained by partly consolidated sandy strata. However, the upland is not continuous, but a maturely dissected escarpment. It has a relatively rapid descent toward the inner lowland, and a very gradual descent to the coast prairies, which become very low, flat and marshy before dipping under the Gulf waters, where they are generally fringed by off-shore reefs.
The coastal plain extends 500 miles (800 km) inland on the axis of the Mississippi embayment. Its inner border affords admirable examples of topographical discordance where it sweeps northwestward square across the trend of the piedmont belt, the ridges and valleys, and the plateau of the Appalachians. All of which are terminated by dipping gently beneath the unconformable cover of the coastal plain strata. In the same way the western side of the embayment, trending south and southwest, passes along the lower southeastern side of the dissected Ozark plateau of southern Missouri and northern and central Arkansas. The southern Missouri and northern Arkansas Ozark plateau resembles in many ways the Appalachian plateau. The Ozarks and Ouachitas make up the U.S. Interior Highlands, the only major mountainous region between the Rocky Mountains and the Appalachian Mountains.
As the coastal plain turns westward toward Texas, it borders the Ouachita Mountains of Arkansas and Oklahoma and the Arbuckle Mountains in southern Oklahoma. The Ouachitas and the Arbuckles may be considered an analog of and possible extension of the Appalachian fold and crystalline belts.
In the embayment of the coastal plain some low escarpment-like belts of hills with associated strips of lowlands suggest the features of a belted coastal plain. The hilly belt or dissected escarpment determined by the Grand Gulf formation in western Mississippi is the most distinct. Important salt deposits occur in the coastal plain strata near the coast. The most striking feature of the embayment is the broad valley which the Mississippi has eroded across it.
The small proportion of total water volume supplied from the great Missouri River basin is due to the light precipitation in that region. The lower Mississippi has no large tributaries from the lower east, but two important ones come from the west. The Mississippi Arkansas drainage area being a little less than the Ohio River and the basin of the Red River of Louisiana being about half as large. The Mississippi River drains an area of about one-third of the United States. The head of the coastal plain embayment is near the junction of the Ohio and the Mississippi. It flows southward for 560 miles (900 km) through the semi-consolidated strata of the plain. The river has eroded a valley about 40 to 50 miles (64 to 80 km) wide enclosed by bluffs one or two hundred feet high in the northern part. These bluffs decrease towards the south, but with local increase of height associated with a decrease in flood plain breadth on the eastern side where the Grand Gulf escarpment is traversed.
This valley in the coastal plain, with the much narrower rock-walled valley of the upper river in the prairie states, is the true valley of the Mississippi River. However, in popular usage, the Mississippi valley is taken to include a large central part of the Mississippi drainage basin.
The valley floor is covered with a floodplain of fine silt, having a southward slope of only half a foot to a mile (100 mm/km). The length of the river itself, from the Ohio mouth to the Gulf is about 1,060 miles (1,710 km) due to its windings. Its mean fall is about 3 inches per mile (50 mm/km). On account of the rapid deposition of sediment near the main channel at times of overflow, the flood plain, as is normally the case on mature valley floors, has a lateral slope of as much as 5, 10, or even 12 ft (3.7 m) in the first mile from the river, but this soon decreases to a less amount. Thus just a short distance from the river, the flood plain is often swampy, unless its surface is there aggraded by the tributary streams. For this reason Louisiana, Arkansas and Mississippi rank immediately after Florida in swamp area.
The great river receives an abundant load of silt from its tributaries, and takes up and lays down silt from its own bed and banks with every change of velocity. The swiftest current follows the outer side of every significant curve in the channel. Thus the concave bank on the side of the fastest part of the river is worn away. Any chance irregularity is exaggerated, and in time a series of large serpentines or meanders is developed, the most-symmetrical examples at present being those near Greenville, Mississippi. The growth of the meanders tends to give the river continually increasing length. This tendency is counteracted by the sudden occurrence of cut-offs from time to time, so that a fairly constant length is maintained.
The floods of the Mississippi usually occur in spring or summer. Owing to the great size of the drainage basin, it seldom happens that the three upper tributaries are simultaneously flooded. It is a serious problem for the lower river if two of the large tributaries flood at the same time. In this case, the lower river will rise to 30, 40 or even 50 feet (15 m). The fall of the river is significantly steepened and its velocity is accelerated down stream from the point of highest rise. Conversely, the fall and the velocity are both diminished up stream from the same point.
The load of silt carried down stream by the river finally, after many halts on the way, reaches the waters of the Gulf. There, the decrease of velocity aided by the salinity of the sea water, causes the formation of a remarkable delta, leaving less aggraded areas as shallow lakes (Lake Pontchartrain on the east, and Grand Lake on the west of the river). The ordinary triangular form of deltas, due to the smoothing of the delta front by sea action, is here wanting, because of the weakness of sea action in comparison with the strength of the current in each of the four distributaries or passes into which the river divides near its mouth.
After constriction from the Mississippi embayment to 250 miles (400 km) in western Louisiana, the coastal plain continues southwestward with this breadth until it narrows to about 130 miles (210 km) in southern Texas near the crossing of the Colorado River (Texas Colorado River, not the Colorado River that flows through the Grand Canyon), but it again widens to 300 miles (480 km) at the national boundary as a joint effect of embayment up the valley of the Rio Grande and of the seaward advance of this river's rounded delta front. These several changes take place in a distance of about 500 miles (800 km). It includes a region of over 100,000 square miles (260,000 km2), less than half of the large state of Texas. A belted arrangement of reliefs and soils, resulting from differential erosion on strata of unlike composition and resistance, characterizes almost the entire area of the coastal plain. Most of the plain is treeless prairie, but the sandier belts are forested. Two of them are known as cross timbers, because their trend is transverse to the general course of the main consequent rivers. An inland extension from the coastal plain in north-central Texas leads to a large escarpment known as Grand Prairie (not structurally included in the coastal plain), upheld at altitudes of 1,200 or 1,300 ft (400 m) by a resistant Cretaceous limestone. This dips gently seaward with its scalloped inland-facing escarpment overlooking a denuded central prairie region of irregular structure and form. Its gentle coastward slope of 16 ft (4.9 m) per mile (3 m/km) is dissected by many branching consequent streams. In its southernpart as it approaches the Colorado river, the escarpment is dissected into a belt of discontinuous hills. The western cross timbers follow a sandy belt along the inner base of the ragged escarpment of Grand Prairie. The eastern cross timbers follow another sandy belt in the lowland between the eastern slope of Grand Prairie and the pale western escarpment of the immediately eastward and lower Black Prairie escarpment. This escarpment is supported at an altitude of 700 ft (210 m) or less by a chalk formation, which gives an infacing slope some 200 ft (61 m) in height.
Its gently undulating or rolling seaward slope of 2 or 3 ft per mile (500 mm/km), covered with marly strata and rich black soil, determines an important cotton district. Then comes the East Texas timber belt, broad in the northeast, narrowing to a point before reaching the Rio Grande, a low and thoroughly dissected escarpment of sandy Eocene strata. This is followed by the Coast Prairie, a very young plain, with a seaward slope of less than 2 ft per mile (400 mm/km), its smooth surface interrupted only by the still more nearly level flood plains of the shallow, consequent river valleys. Near the Colorado river, the dissected escarpment of the Grand Prairie passes southward changing to a more nearly horizontal structure into the dissected Edwards plateau. The Edwards plateau is referred to later as part of the Great Plains. The plateau terminates in a maturely dissected fault scarp approximately 300 or 400 feet (120 m) in height as the northern boundary of the Rio Grande embayment. From the Colorado to the Rio Grande, the Black Prairie, the timber belt and the Coast Prairie merge in a vast plain, little differentiated, overgrown with chaparral (shrub-like trees, often thorny), widening eastward in the Rio Grande delta and extending southward into Mexico.
Although the Coast Prairie is a sea bottom of very modern uplift, it appears already to have suffered a slight movement of depression. Its small rivers all enter embayments. However, the larger rivers seem to have counteracted the encroachment of the sea on the land by a sufficiently active delta building with a resulting forward growth of the land into the sea. The Mississippi has already been mentioned as rapidly building forward its digitate delta. The Rio Grande, next in size, has built its delta about 50 miles (80 km) forward from the general coastline. Since this river is much smaller than the Mississippi, its delta front is rounded by seashore effects. In front of the Brazos and the Colorado, the largest of the Texan rivers, the coast-line is very gently bowed forward as if by delta growth. The sea touches the mainland in a nearly straight shore line. Nearly all the rest of the coast is fringed by off-shore reefs or barrier islands, built up by waves from the very shallow sea bottom. Due to the weak tides, the barrier islands continue in long unbroken stretches between the few inlets.
The northern region uplands are dominated by pine, originally longleaf and slash in the south and shortleaf mixed with hardwoods in the north. These are wildfire-maintained systems that give way to loblolly pine and hardwoods in damper areas and bottomland hardwood forest in extensive lowland drainages. The southern region has tropical and subtropical moist broadleaf forests and western Gulf coastal grasslands. They include large habitats of freshwater wetlands, salt marshes, and coastal mangrove swamps.Much of the lower elevation Gulf Coastal Plain supports wintering waterfowl.
A global satellite study by German and USA scientists spanning the last decade indicates groundwater resources are shrinking due to overuse causing regional water security uncertainty in a changing climate. Surface water quality is declining due to increasing population, depleted streams, and land subsidence along certain coastlines.The Atlantic and Gulf Coastal Plain Aquifer is considered to have low to moderate stress, but the region's economic capacity and land-use patterns signal trends toward a human-dominated stress on water resources.
The geography of Alabama describes a state in the Southeastern United States in North America. Alabama is 30th in size and borders four U.S. states: Mississippi, Tennessee, Georgia, and Florida. It also borders the Gulf of Mexico.
Ghana is a country in Africa, along the Gulf of Guinea, just a few degrees north of the equator.
Sri Lanka, formerly called "Ceylon", is an island nation in the Indian Ocean, southeast of the Indian subcontinent, in a strategic location near major Indian Ocean sea lanes. The nation has a total area of 65,610 km², with 64,740 km² of land and 870 km² of water. Its coastline is 1,340 km (830 mi) long. The main island of Sri Lanka has an area of 65,268 km² – it's the twenty-fifth largest island of the world by area. Dozens of offshore islands account for the remaining 342 km² area. The largest offshore island, Mannar Island, leads to Adam's Bridge.
The Great Plains is the broad expanse of flat land, much of it covered in prairie, steppe, and grassland, that lies west of the Mississippi River tallgrass prairie in the United States and east of the Rocky Mountains in the U.S. and Canada. It embraces:
South Africa occupies the southern tip of Africa, its coastline stretching more than 2,850 kilometres from the desert border with Namibia on the Atlantic (western) coast southwards around the tip of Africa and then northeast to the border with Mozambique on the Indian Ocean. The low-lying coastal zone is narrow for much of that distance, soon giving way to a mountainous escarpment that separates the coast from the high inland plateau. In some places, notably the province of KwaZulu-Natal in the east, a greater distance separates the coast from the escarpment. Although most of the country is classified as semi-arid, it has considerable variation in climate as well as topography.
Prairies are ecosystems considered part of the temperate grasslands, savannas, and shrublands biome by ecologists, based on similar temperate climates, moderate rainfall, and a composition of grasses, herbs, and shrubs, rather than trees, as the dominant vegetation type. Temperate grassland regions include the Pampas of Argentina, Brazil and Uruguay, and the steppe of Ukraine, Russia and Kazakhstan. Lands typically referred to as "prairie" tend to be in North America. The term encompasses the area referred to as the Interior Lowlands of Canada, the United States, and Mexico, which includes all of the Great Plains as well as the wetter, hillier land to the east.
Missouri, a state near the geographical center of the United States, has three distinct physiographic divisions:
An escarpment, or scarp, is a steep slope or long cliff that forms as an effect of faulting or erosion and separates two relatively level areas having differing elevations. Usually scarp and scarp face are used interchangeably with escarpment.
The Intermontane Plateaus of the Western United States is one of eight U.S. Physiographic regions (divisions) of the physical geography of the contiguous United States. The region is composed of intermontane plateaus and mountain ranges. It is subdivided into physiographic provinces, which are each subdivided into physiographic sections.
A coastal plain is flat, low-lying land adjacent to a sea coast. One of the largest coastal plains is located in southeastern United States. The Gulf Coastal Plain of North America extends northwards from the Gulf of Mexico along the Lower Mississippi River to the Ohio River, which is a distance of about 981 miles (1,579 km).
A cuesta is a hill or ridge with a gentle slope on one side, and a steep slope on the other. In geology the term is more specifically applied to a ridge where a harder sedimentary rock overlies a softer layer, the whole being tilted somewhat from the horizontal. This results in a long and gentle backslope called a dip slope that conforms with the dip of resistant strata, called caprock. Where erosion has exposed the frontslope of this, a steep slope or escarpment occurs. The resulting terrain may be called scarpland.
The Mississippi Embayment is a physiographic feature in the south-central United States, part of the Mississippi Alluvial Plain. It is essentially a northward continuation of the fluvial sediments of the Mississippi River Delta to its confluence with the Ohio River at Cairo, Illinois. The current sedimentary area was formed in the Cretaceous and early Cenozoic by the filling with sediment of a pre-existing basin. An explanation for the embayment's formation was put forward by Van Arsdale and Cox in 2007; movement of the earth's crust brought this region over a volcanic "hotspot" in the Earth's mantle causing an upthrust of magma which formed the Appalachian-Ouachita range. Subsequent erosion caused a deep trough that was flooded by the Gulf of Mexico and eventually filled with sediment from the Mississippi River.
The Mississippi River Delta region is a three-million-acre area of land that stretches from Vermilion Bay on the west, to the Chandeleur Islands in the Gulf of Mexico on the southeastern coast of Louisiana. It is part of the Louisiana coastal plain, one of the largest areas of coastal wetlands in the United States. The Mississippi River Delta is the 7th largest river delta on Earth (USGS) and is an important coastal region for the United States, containing more than 2.7 million acres of coastal wetlands and 37% of the estuarine marsh in the conterminous U.S. The coastal area is the nation's largest drainage basin and drains about 41% of the contiguous United States into the Gulf of Mexico at an average rate of 470,000 cubic feet per second.
The Dissected Till Plains are physiographic sections of the Central Lowlands province, which in turn is part of the Interior Plains physiographic division of the United States, located in southern and western Iowa, northeastern Kansas, the southwestern corner of Minnesota, northern Missouri, eastern Nebraska, and southeastern South Dakota.
The Great Escarpment is a major topographical feature in Africa that consists of steep slopes from the high central Southern African plateau downward in the direction of the oceans that surround Southern Africa on three sides. While it lies predominantly within the borders of South Africa, in the east it extends northwards to form the border between Mozambique and Zimbabwe, continuing on beyond the Zambezi River valley to form the Muchinga Escarpment in eastern Zambia. In the west, it continues northwards into Namibia and Angola.
The geography of Texas is diverse and large. Occupying about 7% of the total water and land area of the U.S., it is the second largest state after Alaska, and is the southernmost part of the Great Plains, which end in the south against the folded Sierra Madre Oriental of Mexico. Texas is in the south-central part of the United States of America, and is considered to form part of the U.S. South and also part of the U.S. Southwest.
The Atlantic Plain is one of eight distinct United States physiographic regions. This major division consists of the Continental Shelf and Coastal Plain physiographic provinces. It is the flattest of the U.S. physiographic divisions and stretches over 2,200 miles (3,500 km) in length from Cape Cod to the Mexican border and southward another 1,000 miles (1,600 km) to the Yucatán Peninsula. The central and southern Atlantic Coast is characterized by barrier and drowned valley coasts. The coastal Atlantic plain features nearly continuous barriers interrupted by inlets, large embayments with drowned river valleys, and extensive wetlands and marshes. The Atlantic plain slopes gently seaward from the inland highlands in a series of terraces. This gentle slope continues far into the Atlantic and Gulf of Mexico, forming the continental shelf. The relief at the land-sea interface is so low that the boundary between them is often blurry and indistinct, especially along stretches of the Louisiana bayous and the Florida Everglades.