False-color image of the larger Mississippi Delta

Closeup of the currently active delta front

Mississippi Delta Lobes

The Mississippi River Delta is the modern area of land (the river delta) built up by alluvium deposited by the Mississippi River as it slows down and enters the Gulf of Mexico. The deltaic process has, over the past 5,000 years, caused the coastline of south Louisiana to advance gulfward from 15 to 50 miles (24 to 80 km). Image File history File links Download high resolution version (1151x720, 223 KB) Summary Mississippi River Delta. ... Image File history File links Download high resolution version (1151x720, 223 KB) Summary Mississippi River Delta. ... Mississippi Delta from space image description here larger version here Image courtesy: NASA/JPL-Caltech File links The following pages link to this file: Mississippi Delta Categories: NASA images ... Mississippi Delta from space image description here larger version here Image courtesy: NASA/JPL-Caltech File links The following pages link to this file: Mississippi Delta Categories: NASA images ... Image File history File links Licensing File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File links Licensing File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... The Holocene epoch is a geological period that extends from the present day back to about 10,000 radiocarbon years, approximately 11,430 ± 130 calendar years BP (between 9560 and 9300 BC). ... Nile River delta, as seen from Earth orbit. ... Alluvium is soil or sediments deposited by a river or other running water. ... The Mississippi River, derived from the old Ojibwe word misi-ziibi meaning great river (gichi-ziibi big river at its headwaters), is the second-longest river in the United States; the longest is the Missouri River, which flows into the Mississippi. ... Gulf of Mexico in 3D perspective. ...

It is a biologically significant region, comprising 3 million acres (12,000 km²) of coastal wetlands and 40 % of the salt marsh in the contiguous United States. It is also a commercially significant region, supporting the economy of New Orleans with significant shipping traffic, providing 16 to 18 % of the US oil supply, and providing 16 % of the US's fisheries harvest, including shrimp, crabs, and crayfish. This article is about marsh, a type of wetland. ... New Orleans is the largest city in the state of Louisiana, United States of America. ... Port Fourchon is a small community on the southern tip of Lafourche Parish, Louisiana, on the Gulf of Mexico. ... Superfamilies Alpheoidea Atyoidea Bresilioidea Campylonotoidea Crangonoidea Galatheacaridoidea Nematocarcinoidea Oplophoroidea Palaemonoidea Pandaloidea Pasiphaeoidea Procaridoidea Processoidea Psalidopodoidea Stylodactyloidea True shrimp are small, swimming, decapod crustaceans classified in the infraorder Caridea, found widely around the world in both fresh and salt water. ... Superfamilies Dromiacea Homolodromioidea Dromioidea Homoloidea Eubrachyura Raninoidea Cyclodorippoidea Dorippoidea Calappoidea Leucosioidea Majoidea Hymenosomatoidea Parthenopoidea Retroplumoidea Cancroidea Portunoidea Bythograeoidea Xanthoidea Bellioidea Potamoidea Pseudothelphusoidea Gecarcinucoidea Cryptochiroidea Pinnotheroidea * Ocypodoidea * Grapsoidea * An asterisk (*) marks the crabs included in the clade Thoracotremata. ... Families Astacoidea   Astacidae   Cambaridae Parastacoidea   Parastacidae Crayfish, often referred to as crawfish or crawdad, are freshwater crustaceans resembling small lobsters, to which they are closely related. ...

Recent influences

Every thousand years or so, the Mississippi river has changed course. Each Mississippi River deltaic cycle was initiated by a gradual capture of the Mississippi River by a distributary which offered a shorter and steeper route to the Gulf of Mexico. After abandonment of an older delta lobe, which would cut off the primary supply of fresh water and sediment, an area would undergo compaction, subsidence, and erosion. The old delta lobe would begin to retreat as the gulf advanced, forming bayous, lakes, bays, and sounds. A road destroyed by subsidence and shear. ... Big Cypress Bayou in Jefferson, Texas off of U.S. Route 59. ... Northern Øresund Puget Sound and Mt. ...

750 years ago, the Mississippi abandoned its main course through the Lafourche Bayou and began flowing in the current direction to the area where New Orleans is located. 550 years ago, it began extending further out into the Gulf of Mexico. Bayou Lafourche is a bayou in southeastern Louisiana, United States, that flows into the Gulf of Mexico. ...

In the last 100 years or so, the river has been diverting more of its flow to the Atchafalaya River, which branches off some 60 miles (95 km) northwest of New Orleans. In the 1950’s, engineers observed that the Mississippi would soon abandon its current channel as the mainstream, and instead migrate to the Atchafalaya. Because there is a considerable amount of economic development along the current path of the Mississippi, and because extensive flooding and evacuation would occur in the new area, Congress instructed the Army Corps of Engineers to maintain the then-present 70% / 30% distribution of water between the Lower Mississippi and the Atchafalaya River channels respectively. They did so by building the Old River Control Structure which consisted of massive floodgates that could be opened and closed as needed at the entrance to the Old River. The Atchafalaya River is a distributary of the Mississippi and Red rivers, approximately 170 mi (270 km) long, in south central Louisiana in the United States. ... New Orleans is the largest city in the state of Louisiana, United States of America. ... United States Army Corps of Engineers logo The United States Army Corps of Engineers, or USACE, is made up of some 34,600 military men and women. ... The Old River Control Structure was built by the U.S. Army Corps of Engineers at the confluence of the Mississippi and Atchafalaya Rivers in order to maintain the water distribution between the two at 70% and 30% respectively. ...

Man-made changes to other parts of the Mississippi River have a pronounced effect on the Delta region. Dams, artificial channeling, and land conservation measures have caused a decrease in sediment carried into the delta region, decreasing the rate of build up of the Delta.

At the same time, the rate of loss of the Delta has recently increased past the rate of build up, causing a net loss of wetlands in the Delta area. The rise of the sea level has also caused increased erosion, as fresh water vegetation previously protecting against erosion dies due to the influx of salt water. Subsidence has increased. For considerations of sea level change, in particular rise associated with possible global warming, see sea level rise. ... A road destroyed by subsidence and shear. ...

History

Build-up of the Gulf of Mexico shoreline due to the outflow of the Mississippi River has been occurring in a periodic fashion since the late Jurassic period. This same process is responsible for build up of the larger Mississippi embayment, however the delta region is the most recent, ecologically distinct, portion. Gulf of Mexico in 3D perspective. ... The Jurassic Period is a major unit of the geologic timescale that extends from about 200 Ma (million years ago), at the end of the Triassic to 146 Ma, at the beginning of the Cretaceous. ... This article may be too technical for most readers to understand. ... Ernst Haeckel coined the term oekologie in 1866. ...

The latest cycle of delta formation can be traced to the pleistocene epoch, when a large amount of ocean water was tied up in glaciers. The sea level was 300-400 feet (~100m) below present level, and causing the mouth of the Mississippi to be located further out into the Gulf of Mexico. 10,000 years ago, the glaciers began to melt, and the sea level began to rise. 5,000 - 6,000 years ago, the sea level stabilized, and formation of recognizable modern deltas began. The Pleistocene epoch (IPA: ) is part of the geologic timescale. ... For considerations of sea level change, in particular rise associated with possible global warming, see sea level rise. ... Image File history File links SE-USshoreline. ...

Lake Pontchartrain was formed during the evolution of two separate delta lobes. 4000-3800 years ago, the Cocodrie lobe * expanded over the area where New Orleans presently resides, forming the lake's southern shore. 2800-2600 years ago, the St. Bernard lobe * pushed forward and completed the lake's eastern shoreline. [1] To meet Wikipedias quality standards, this article or section may require cleanup. ... New Orleans is the largest city in the state of Louisiana, United States of America. ...

See also

• Delta switching
• Mississippi Valley Division of the United States Army Corps of Engineers
• Mississippi embayment
• New York Times article on possibility of moving the Mississippi

Delta switching, also known as avulsion, is the process by which some rivers--such as the Mississippi River--change their course near their deltas. ... The United States Army Corps of Engineers Mississippi Valley Division (MVD) and the complementary Mississippi River Commission (MRC) are responsible for maintaining the Mississippi River as a navigable waterway while preventing flooding. ... United States Army Corps of Engineers logo The United States Army Corps of Engineers, or USACE, is made up of some 34,600 civilian and 650 military men and women. ... This article may be too technical for most readers to understand. ...

Sources

• Kolb,van Lopik (1958). Geology of the Mississippi River deltaic plain, southeastern Louisiana. Technical Report 3-483. Vicksburg, MS: U.S. Army Corps of Engineers Waterways Experiment Station. (PDF, 6.86MB) [2]
• LA Coast / USGS — Mississippi River Delta Basin
• Emporia State University — The Mississippi Embayment, Quaternary Geology
• USGS, Status and Trends — Coastal Louisiana
• Detrital Depositional Sequences of the Mississippi River Deltaic Plain, George F. Hart, Ph. D.
• USGS — Geologic History of the Lake Pontchartrain Basin
• Louisiana State University — Wetlands: Impacts of Energy Development in the Mississippi Delta
• USGS — Louisiana Coastal Area - Ecosystem Restoration Plan

External links and sources

• Google Maps - satellite imagery
• US Army Corps of Engineers, New Orleans District
• U.S. Geological Survey - Mississippi Delta, Changes Over Time
• U.S. Geological Survey - Causes of hot-spot wetland loss in the Mississippi delta plain
• U.S. Geological Survey - Louisiana Coastal Wetlands: A Resource At Risk
• NOW with Bill Moyers - Losing Ground
• visibleearth.nasa.gov - True-color image hilighting sediment outflow from delta front
• lacoast.gov - Land loss map of the delta front
• Barataria Terrebonne National Estuary