Mississippi River Delta

The Mississippi River Delta is the confluence of the Mississippi River with the Gulf of Mexico in Louisiana, southeastern United States. The river delta is a area of land that stretches from Vermilion Bay on the west, to the Chandeleur Islands in the east, on Louisiana's southeastern coast.Couvillion, B.R.; Barras, J.A.; Steyer, G.D.; Sleavin, William; Fischer, Michelle; Beck, Holly; Trahan, Nadine; Griffin, Brad; and Heckman, David, 2011, Land area change in coastal Louisiana from 1932 to 2010: U.S. Geological Survey Scientific Investigations Map 3164, scale 1:265,000, 12 p. pamphlet. It is part of the Gulf of Mexico and the Louisiana coastal plain, one of the largest areas of coastal wetlands in the United States.Louisiana's Coastal Area. "Ecosystem Restoration." LCA – Louisiana Coastal Area. 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 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 .

History and growth

The modern Mississippi River Delta formed over the last approximately 4,500 years as the Mississippi River deposited sand, clay and silt along its banks and in adjacent basins. The Mississippi River Delta is a river-dominated delta system, influenced by the largest river system in North America. The shape of the current birdfoot delta reflects the dominance the river exerts over the other hydrologic and geologic processes at play in the northern Gulf of Mexico. Prior to the extensive leveeing of the Mississippi River that began in the 1930s, the river avulsed its course in search of a shorter route to the Gulf of Mexico approximately every 1,000–1,500 years. The prehistoric and historic delta lobes of the Mississippi River Delta have influenced the formation of the Louisiana coastline and led to the creation of over of coastal wetlands.

As the river changed course, the natural flow of freshwater and sediment changed as well, resulting in periods of land building and land loss in different areas of the delta. This process by which the river changes course is known as avulsion, or delta-switching, and forms the variety of landscapes that make up the Mississippi River Delta.

The Atchafalaya River is the largest distributary of the Mississippi River and is also considered to be an influential part of the continual land-building processes within the Mississippi River Delta. The river's tributary channel was formed approximately 500 years ago and the Atchafalaya and Wax Lake deltas emerged around the middle of the twentieth century.

Starting with the earliest European settlement, people have struggled with the delta's natural cycle of floods, progradation, and transgression. Increased economic development and human habitation in the region created a desire to protect society from the threats posed by the river. Beginning in the 20th century, advances in technology and engineering allowed humans to alter the river in fundamental ways. Although these changes successfully shielded many people from danger and enabled significant economic development in the region, they have proven to have profoundly negative effects on the downstream delta.

Geologic history

The formation of the Mississippi River Delta can be traced back to the late Cretaceous Period, approximately 100 million years ago, with the creation of the Mississippi embayment. The embayment began focusing sediment into the Gulf of Mexico, which facilitated the deltaic land-building processes for the future. During the Paleogene Period (approx. 65.5 to 23 million years ago), a series of smaller scale, regional rivers entered present-day southern Louisiana allowing an increase in dispersion of sediment deposition into the delta region. The Mississippi embayment then became a primary focus of sediment deposition during the Miocene Epoch (approx. 23 to 5.3 million years ago), which built the foundation of the modern delta region. The modern day Mississippi River Delta plain began to evolve during the Holocene Epoch (around 7,500 to 8,000 years ago) due to the deceleration of sea level rise and the natural shifting of the river's course every 1,000–1,500 years.

The delta cycle refers to a dynamic process whereby the river deposits sediment at its outfall, growing a delta lobe, then eventually, seeking a shorter path to the sea, abandons its previous course and associated delta. After the river changes course and abandons the delta headland, the region experiences land loss due to the processes of subsidence, erosion of the marsh shoreline, and the natural redistribution of sands deposited along the delta that create the barrier islands. The delta cycle contains the natural process of land loss and land gain, due to the directionality and discharge of the river. This process formed the bays, bayous, coastal wetlands, and barrier islands that make up the coastline of Louisiana.

The Mississippi River major deltaic cycle began over 7,000 years ago, eventually forming six delta complexes which are major depositional elements of a delta plain. The Mississippi River Delta complexes consist of smaller areas known as delta lobes, which contain the basins and other natural landscapes of the coastline.

The six Mississippi River Delta complexes are as follows:
:1. The ''Maringouin delta'' formed 7,500 to 5,500 years ago when relative sea level rapidly rose.
:2. The ''Teche delta'' formed 5,500 to 3,500 years ago after relative sea level rise decelerated.
:3. The ''St. Bernard delta'' formed 4,000 to 2,000 years ago following an avulsion that caused the river's relocation to the east of present-day New Orleans.
:4. The ''Lafourche delta'' formed 2,500 to 500 years ago from a second avulsion that caused the river to relocate to the west of present-day New Orleans.
:5. Modern day development (over the past 1,500 years) formed the ''Plaquemines-Balize delta'', also known as Bird's Foot Delta, between the St. Bernard and Lafourche delta.
:6. Diversion to the Atchafalaya began 500 years ago with the ''Atchafalaya'' and ''Wax Lake Outlet deltas'' emerging in the mid-20th century. More recent influences created the most recent land building processes in the Wax Lake Outlet when the Wax Lake Outlet channel was created in 1942 to reduce water levels at Morgan City.

Social, economic and cultural history

History

The history and culture that is linked to the Mississippi River Delta is as unique as its geologic landscape. The mouth of the Mississippi River was discovered in 1519 by Alvarez de Pineda of Spain. Robert Cavelier de La Salle claimed the territory around the mouth of the Mississippi River for France in 1682, and the region grew with importance with its strategic location for trade and security.

In 1699 the French built their first crude fort at La Balize, on the Southeast Pass in Pass á Loutre, to control passage on the Mississippi. By 1721, they had built the wooden lighthouse-type structure ( means 'seamark' in French) that gave the settlement its name. Built in the marshes, the village was vulnerable to hurricane damage. In addition, ships had to deal with the shifting conditions of tides, currents, and mudflats through the mouth of the river. From 1700 to 1888, the main shipping channel was changed four times in response to shifting sandbars, mudflats, and hurricanes.

In 1803, the United States purchased Louisiana from Napoleon. During this period, the economic and political significance of New Orleans and the mouth of the Mississippi River increased, and it became an integral part of the nation's farming industries. Due to the influx of nutrient-rich soil from the Mississippi River, the delta is a prime area for the farming of sugar cane, cotton, and indigo—crops that were introduced into Louisiana farmlands during the pre-Civil War era. Many of these processes are important resources that the delta still provides today.

The importance of navigation and trade on the Mississippi only increased after the Civil War, and like the river itself, this economic development eventually flowed into the delta. In the 1870s, former delta swamplands were being transformed, via levee construction, into fertile farmland. Timber companies began harvesting lucrative forests and planters followed, taking advantage of the new agricultural opportunities. More railroads entered the area, replacing steamboats as the primary means of transporting the delta's rich natural bounty.

With the opening of the Panama Canal in 1914, the Mississippi River Delta became an even more important transportation artery. In addition to shipping, local and commercial fisheries continued to expand. The discovery of vast oil and gas deposits brought further economic and environmental changes to the delta. Despite these profound changes, the delta today remains very much rooted in the vibrant cultural and social traditions of its residents.

People

The Mississippi River Delta is home to more than two million people. The location of the delta at the mouth of the Mississippi River allowed for the area to be a cultural gateway into the United States, and influenced the mix of nationalities which settled in the area over time, forming the diversity of the region.

Louisiana's first 18th century colonists were French, but they were soon joined by Spanish and Acadian settlers. The region has been home to other European-immigrant ethnic groups, beginning in the 19th century, including German, Sicilian, and Irish. There are also the Africans, West Indians, and Native Americans in the mix. The combination of these groups over time has created the special culture found in the Mississippi River Delta.

Two unique groups are the Creoles and the Cajuns.History and Culture of the Lower Mississippi River Delta. 2001. Draft Heritage Study and Environmental Assessment. National Park Service
In general terms, Creole refers to a black, white, or mixed-race native of Louisiana. Creoles descended from the union of various ethnic groups in Louisiana, and they are often categorized according to their heritage. Creole populations before 1803 were typically born of French and/or Spanish parents; as such, they kept their European characteristics and cultures. A sub-group is known as the " Creoles of color," born of the mingling of African, European, and Native American identities. During the colonial period, the mixed-race Creoles were usually free from bondage, obtained an education, and often owned businesses and property.

The Cajuns are another ethnic group in southern Louisiana; they primarily consider themselves to be descendants of the Acadian settlers who were expelled from Nova Scotia by the British after the French and Indian War, when France lost its North American colonies. The Cajuns have intermarried with all ethnicities, profoundly influencing the culture of Louisiana. The Creole and Cajun cultures possessed distinct identities and remain strong influences in the Mississippi River Delta. They continue to shape preferences of food, music, and art, as well as to maintain the unique identities existing in the southernmost parts of the region. Both cultures speak a form of French; but they are considered to be autonomous and distinct dialects.

Culture

From 1910 to 1920, New Orleans