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83-611: The Wabash Bridge carries one railroad track across the Mississippi River between Hannibal, Missouri , and Pike County, Illinois . Built by the Wabash Railroad , the bridge is today owned by the Norfolk Southern Railway . On May 3, 1982, the towboat Northern King lost power in one engine while pushing 12 grain-filled barges in heavy currents. The craft struck a 250-foot (76 m) truss span, which collapsed into

166-532: A large mound of sand spanning the width of the river 55 feet below the surface, allowing fresh water and large cargo ships to pass over. Fresh river water flowing from the Mississippi into the Gulf of Mexico does not mix into the salt water immediately. The images from NASA 's MODIS show a large plume of fresh water, which appears as a dark ribbon against the lighter-blue surrounding waters. These images demonstrate that

249-703: A length of 3,710 miles (5,971 km), making it the fourth longest river in the world after the Nile , Amazon , and Yangtze . When measured by the largest stream source (by water volume), the Ohio River , by extension the Allegheny River , would be the source, and the Mississippi would begin in Pennsylvania . At its source at Lake Itasca , the Mississippi River is about 3 feet (0.91 m) deep. The average depth of

332-786: A major generator of silt, which accumulated to form the fertile soils of north India and Bangladesh, and the loess of central Asia and north China. Loess has long been thought to be absent or rare in deserts lacking nearby mountains (Sahara, Australia). However, laboratory experiments show eolian and fluvial processes can be quite efficient at producing silt, as can weathering in tropical climates. Silt seems to be produced in great quantities in dust storms, and silt deposits found in Israel, Tunisia, Nigeria, and Saudi Arabia cannot be attributed to glaciation. Furthermore, desert source areas in Asia may be more important for loess formation than previously thought. Part of

415-478: A natural process known as avulsion or delta switching, the lower Mississippi River has shifted its final course to the mouth of the Gulf of Mexico every thousand years or so. This occurs because the deposits of silt and sediment begin to clog its channel, raising the river's level and causing it to eventually find a steeper, more direct route to the Gulf of Mexico. The abandoned distributaries diminish in volume and form what are known as bayous . This process has, over

498-440: A number of mechanisms. However, the main process is likely abrasion through transport, including fluvial comminution , aeolian attrition and glacial grinding. Because silt deposits (such as loess , a soil composed mostly of silt ) seem to be associated with glaciated or mountainous regions in Asia and North America, much emphasis has been placed on glacial grinding as a source of silt. High Asia has been identified as

581-482: A platy or bladed shape. This may be characteristic of how larger grains abrade, or reflect the shape of small quartz grains in foliated metamorphic rock , or arise from authigenic growth of quartz grains parallel to bedding in sedimentary rock . Theoretically, particles formed by random fracturing of an isotropic material, such as quartz, naturally tend to be blade-shaped. The size of silt grains produced by abrasion or shattering of larger grains may reflect defects in

664-615: A pollutant in water the phenomenon is known as siltation . Silt deposited by the Mississippi River throughout the 20th century has decreased due to a system of levees , contributing to the disappearance of protective wetlands and barrier islands in the delta region surrounding New Orleans . In southeast Bangladesh, in the Noakhali district , cross dams were built in the 1960s whereby silt gradually started forming new land called "chars". The district of Noakhali has gained more than 73 square kilometres (28 sq mi) of land in

747-522: Is detritus (fragments of weathered and eroded rock) with properties intermediate between sand and clay . A more precise definition of silt used by geologists is that it is detrital particles with sizes between 1/256 and 1/16 mm (about 4 to 63 microns). This corresponds to particles between 8 and 4 phi units on the Krumbein phi scale . Other geologists define silt as detrital particles between 2 and 63 microns or 9 to 4 phi units. A third definition

830-750: Is 208,200 cu ft/s (5,900 m /s). Thus, by volume, the main branch of the Mississippi River system at Cairo can be considered to be the Ohio River (and the Allegheny River further upstream), rather than the Middle Mississippi. In addition to the Ohio River , the major tributaries of the Lower Mississippi River are the White River , flowing in at the White River National Wildlife Refuge in east-central Arkansas;

913-558: Is a meandering river in a broad, flat area, only rarely flowing alongside a bluff (as at Vicksburg, Mississippi ). The Mississippi River is known as the Middle Mississippi from the Upper Mississippi River's confluence with the Missouri River at St. Louis, Missouri , for 190 miles (310 km) to its confluence with the Ohio River at Cairo, Illinois . The Middle Mississippi is relatively free-flowing. From St. Louis to

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996-615: Is a particular challenge for civil engineering . The failure of the Teton Dam has been attributed to the use of loess from the Snake River floodplain in the core of the dam. Loess lacks the necessary plasticity for use in a dam core, but its properties were poorly understood, even by the U.S. Bureau of Reclamation , with its wealth of experience building earthen dams . Silt is susceptible to liquefaction during strong earthquakes due to its lack of plasticity. This has raised concerns about

1079-494: Is called the Lower Mississippi River from its confluence with the Ohio River to its mouth at the Gulf of Mexico, a distance of about 1,000 miles (1,600 km). At the confluence of the Ohio and the Middle Mississippi, the long-term mean discharge of the Ohio at Cairo, Illinois is 281,500 cubic feet per second (7,970 cubic meters per second), while the long-term mean discharge of the Mississippi at Thebes, Illinois (just upriver from Cairo)

1162-703: Is carried through the vadose zone to be deposited in pore space. ASTM American Standard of Testing Materials: 200 sieve – 0.005 mm. USDA United States Department of Agriculture 0.05–0.002 mm. ISSS International Society of Soil Science 0.02–0.002 mm. Civil engineers in the United States define silt as material made of particles that pass a number 200 sieve (0.074 mm or less) but show little plasticity when wet and little cohesion when air-dried. The International Society of Soil Science (ISSS) defines silt as soil containing 80% or more of particles between 0.002 mm to 0.02 mm in size while

1245-589: Is common throughout the geologic record , but it seems to be particularly common in Quaternary formations. This may be because deposition of silt is favored by the glaciation and arctic conditions characteristic of the Quaternary. Silt is sometimes known as rock flour or glacier meal , especially when produced by glacial action. Silt suspended in water draining from glaciers is sometimes known as rock milk or moonmilk . A simple explanation for silt formation

1328-868: Is controlled and managed as a series of pools created by 26 locks and dams. The Upper Mississippi River is joined by the Minnesota River at Fort Snelling in the Twin Cities ; the St. Croix River near Prescott, Wisconsin ; the Cannon River near Red Wing, Minnesota ; the Zumbro River at Wabasha, Minnesota ; the Black , La Crosse , and Root rivers in La Crosse, Wisconsin ; the Wisconsin River at Prairie du Chien, Wisconsin ;

1411-509: Is largely a multi-thread stream with many bars and islands. From its confluence with the St. Croix River downstream to Dubuque, Iowa , the river is entrenched, with high bedrock bluffs lying on either side. The height of these bluffs decreases to the south of Dubuque, though they are still significant through Savanna, Illinois . This topography contrasts strongly with the Lower Mississippi, which

1494-413: Is often found in mudrock as thin laminae , as clumps, or dispersed throughout the rock. Laminae suggest deposition in a weak current that winnows the silt of clay, while clumps suggest an origin as fecal pellets . Where silt is dispersed throughout the mudrock, it likely was deposited by rapid processes, such as flocculation . Sedimentary rock composed mainly of silt is known as siltstone . Silt

1577-528: Is soil rich in silt which makes up some of the most fertile agricultural land on Earth. However, silt is very vulnerable to erosion, and it has poor mechanical properties, making construction on silty soil problematic. The failure of the Teton Dam in 1976 has been attributed to the use of unsuitable loess in the dam core, and liquefication of silty soil is a significant earthquake hazard. Windblown and waterborne silt are significant forms of environmental pollution, often exacerbated by poor farming practices. Silt

1660-634: Is that it is a straightforward continuation to a smaller scale of the disintegration of rock into gravel and sand. However, the presence of a Tanner gap between sand and silt (a scarcity of particles with sizes between 30 and 120 microns) suggests that different physical processes produce sand and silt. The mechanisms of silt formation have been studied extensively in the laboratory and compared with field observations. These show that silt formation requires high-energy processes acting over long periods of time, but such processes are present in diverse geologic settings. Quartz silt grains are usually found to have

1743-443: Is that silt is fine-grained detrital material composed of quartz rather than clay minerals . Since most clay mineral particles are smaller than 2 microns, while most detrital particles between 2 and 63 microns in size are composed of broken quartz grains, there is good agreement between these definitions in practice. The upper size limit of 1/16 mm or 63 microns corresponds to the smallest particles that can be discerned with

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1826-528: Is the only true waterfall on the entire Mississippi River. The water elevation continues to drop steeply as it passes through the gorge carved by the waterfall. After the completion of the St. Anthony Falls Lock and Dam in 1963, the river's head of navigation moved upstream, to the Coon Rapids Dam . However, the Locks were closed in 2015 to control the spread of invasive Asian carp , making Minneapolis once again

1909-604: The American Civil War , the Mississippi's capture by Union forces marked a turning point towards victory , due to the river's strategic importance to the Confederate war effort. Because of the substantial growth of cities and the larger ships and barges that replaced steamboats, the first decades of the 20th century saw the construction of massive engineering works such as levees , locks and dams , often built in combination. A major focus of this work has been to prevent

1992-831: The Arkansas River , joining the Mississippi at Arkansas Post ; the Big Black River in Mississippi; and the Yazoo River , meeting the Mississippi at Vicksburg, Mississippi . Deliberate water diversion at the Old River Control Structure in Louisiana allows the Atchafalaya River in Louisiana to be a major distributary of the Mississippi River, with 30% of the combined flow of the Mississippi and Red Rivers flowing to

2075-559: The Gulf of Mexico , part of the Atlantic Ocean. The total catchment of the Mississippi River covers nearly 40% of the landmass of the continental United States. The highest point within the watershed is also the highest point of the Rocky Mountains , Mount Elbert at 14,440 feet (4,400 m). In the United States, the Mississippi River drains the majority of the area between the crest of

2158-582: The Minnesota River , James River , and Milk River valleys. When the ice sheet completely retreated, many of these "temporary" rivers found paths to Hudson Bay or the Arctic Ocean, leaving the Mississippi Basin with many features "over-sized" for the existing rivers to have carved in the same time period. Ice sheets during the Illinoian Stage , about 300,000 to 132,000 years before present, blocked

2241-537: The Nile and Niger River deltas. Bangladesh is largely underlain by silt deposits of the Ganges delta. Silt is also abundant in northern China, central Asia, and North America. However, silt is relatively uncommon in the tropical regions of the world. Silt is commonly found in suspension in river water, and it makes up over 0.2% of river sand. It is abundant in the matrix between the larger sand grains of graywackes . Modern mud has an average silt content of 45%. Silt

2324-1226: The Rock River at the Quad Cities ; the Iowa River near Wapello, Iowa ; the Skunk River south of Burlington, Iowa ; and the Des Moines River at Keokuk, Iowa . Other major tributaries of the Upper Mississippi include the Crow River in Minnesota, the Chippewa River in Wisconsin, the Maquoketa River and the Wapsipinicon River in Iowa, and the Illinois River in Illinois. The Upper Mississippi

2407-836: The Rocky Mountains and the crest of the Appalachian Mountains , except for various regions drained to Hudson Bay by the Red River of the North ; to the Atlantic Ocean by the Great Lakes and the Saint Lawrence River ; and to the Gulf of Mexico by the Rio Grande , the Alabama and Tombigbee rivers, the Chattahoochee and Appalachicola rivers, and various smaller coastal waterways along

2490-429: The headwaters region and serve multiple purposes, including power generation and recreation. The remaining 29 dams, beginning in downtown Minneapolis, all contain locks and were constructed to improve commercial navigation of the upper river. Taken as a whole, these 43 dams significantly shape the geography and influence the ecology of the upper river. Beginning just below Saint Paul, Minnesota , and continuing throughout

2573-483: The most recent Ice Age . The southernmost extent of this enormous glaciation extended well into the present-day United States and Mississippi basin. When the ice sheet began to recede, hundreds of feet of rich sediment were deposited, creating the flat and fertile landscape of the Mississippi Valley. During the melt, giant glacial rivers found drainage paths into the Mississippi watershed, creating such features as

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2656-561: The Earth's mantle (specifically, the Bermuda hotspot ) that was undergoing a period of intense activity. The upwelling of magma from the hotspot forced the further uplift to a height of perhaps 2–3 km of part of the Appalachian-Ouachita range, forming an arch that blocked southbound water flows. The uplifted land quickly eroded and, as North America moved away from the hot spot and as

2739-610: The French rendering of the Anishinaabe ( Ojibwe or Algonquin ) name for the river, Misi-ziibi (Great River). In the 18th century, the river was set by the Treaty of Paris as, for the most part, the western border of the new United States. With the Louisiana Purchase and the country's westward expansion, it became a convenient boundary line between the western and eastern halves of

2822-648: The Gulf of Mexico by this route, rather than continuing down the Mississippi's current channel past Baton Rouge and New Orleans on a longer route to the Gulf. Although the Red River was once an additional tributary, its water now flows separately into the Gulf of Mexico through the Atchafalaya River. The Mississippi River has the world's fourth-largest drainage basin ("watershed" or "catchment"). The basin covers more than 1,245,000 square miles (3,220,000 km ), including all or parts of 32 U.S. states and two Canadian provinces. The drainage basin empties into

2905-482: The Gulf. The Mississippi River empties into the Gulf of Mexico about 100 miles (160 km) downstream from New Orleans. Measurements of the length of the Mississippi from Lake Itasca to the Gulf of Mexico vary somewhat, but the United States Geological Survey 's number is 2,340 miles (3,766 km). The retention time from Lake Itasca to the Gulf is typically about 90 days; while speed varies along

2988-462: The Illinoian Stage. Timeline of outflow course changes In March 1876, the Mississippi suddenly changed course near the settlement of Reverie, Tennessee , leaving a small part of Tipton County, Tennessee , attached to Arkansas and separated from the rest of Tennessee by the new river channel. Since this event was an avulsion , rather than the effect of incremental erosion and deposition,

3071-562: The Midwestern and eastern U.S. These earthquakes created Reelfoot Lake in Tennessee from the altered landscape near the river. When measured from its traditional source at Lake Itasca , the Mississippi has a length of 2,340 miles (3,766 km). When measured from its longest stream source (most distant source from the sea), Brower's Spring in Montana , the source of the Missouri River , it has

3154-473: The Mississippi River between Saint Paul and Saint Louis is between 9 and 12 feet (2.7–3.7 m) deep, the deepest part being Lake Pepin , which averages 20–32 feet (6–10 m) deep and has a maximum depth of 60 feet (18 m). Between where the Missouri River joins the Mississippi at Saint Louis, Missouri, and Cairo, Illinois, the depth averages 30 feet (9 m). Below Cairo, where the Ohio River joins,

3237-411: The Mississippi River has experienced numerous large and small changes to its main course, as well as additions, deletions, and other changes among its numerous tributaries, and the lower Mississippi River has used different pathways as its main channel to the Gulf of Mexico across the delta region. As Pangaea began to break up about 95 million years ago, North America passed over a volcanic " hotspot " in

3320-464: The Mississippi River near New Madrid, Missouri , between Memphis and St. Louis, is related to an aulacogen (failed rift) that formed at the same time as the Gulf of Mexico. This area is still quite active seismically. Four great earthquakes in 1811 and 1812 , estimated at 8 on the Richter magnitude scale , had tremendous local effects in the then sparsely settled area, and were felt in many other places in

3403-445: The Mississippi River. Silt Silt is a common material, making up 45% of average modern mud . It is found in many river deltas and as wind-deposited accumulations, particularly in central Asia, north China, and North America. It is produced in both very hot climates (through such processes as collisions of quartz grains in dust storms ) and very cold climates (through such processes as glacial grinding of quartz grains.) Loess

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3486-452: The Mississippi near Rock Island, Illinois, diverting it to its present channel farther to the west, the current western border of Illinois. The Hennepin Canal roughly follows the ancient channel of the Mississippi downstream from Rock Island to Hennepin, Illinois . South of Hennepin, to Alton, Illinois , the current Illinois River follows the ancient channel used by the Mississippi River before

3569-757: The Missouri River; the Middle Mississippi, which is downriver from the Missouri to the Ohio River; and the Lower Mississippi , which flows from the Ohio to the Gulf of Mexico. The Upper Mississippi runs from its headwaters to its confluence with the Missouri River at St. Louis, Missouri. It is divided into two sections: The source of the Upper Mississippi branch is traditionally accepted as Lake Itasca , 1,475 feet (450 m) above sea level in Itasca State Park in Clearwater County, Minnesota . The name Itasca

3652-567: The Ohio River confluence, the Middle Mississippi falls 220 feet (67 m) over 180 miles (290 km) for an average rate of 1.2 feet per mile (23 cm/km). At its confluence with the Ohio River, the Middle Mississippi is 315 feet (96 m) above sea level. Apart from the Missouri and Meramec rivers of Missouri and the Kaskaskia River of Illinois, no major tributaries enter the Middle Mississippi River. The Mississippi River

3735-430: The U.S. Department of Agriculture puts the cutoff at 0.05mm. The term silt is also used informally for material containing much sand and clay as well as silt-sized particles, or for mud suspended in water. Silt is a very common material, and it has been estimated that there are a billion trillion trillion (10 ) silt grains worldwide. Silt is abundant in eolian and alluvial deposits, including river deltas , such as

3818-430: The Upper Mississippi River is the Upper St. Anthony Falls Lock and Dam in Minneapolis. Above the dam, the river's elevation is 799 feet (244 m). Below the dam, the river's elevation is 750 feet (230 m). This 49-foot (15 m) drop is the largest of all the Mississippi River locks and dams. The origin of the dramatic drop is a waterfall preserved adjacent to the lock under an apron of concrete. Saint Anthony Falls

3901-426: The Upper Mississippi is a simple steel culvert, through which the river (locally named "Nicolet Creek") flows north from Lake Nicolet under "Wilderness Road" to the West Arm of Lake Itasca, within Itasca State Park . The earliest bridge across the Mississippi River was built in 1855. It spanned the river in Minneapolis where the current Hennepin Avenue Bridge is located. No highway or railroad tunnels cross under

3984-555: The areas drained by them. Denser salt water from the Gulf of Mexico forms a salt wedge along the river bottom near the mouth of the river, while fresh water flows near the surface. In drought years, with less fresh water to push it out, salt water can travel many miles upstream—64 miles (103 km) in 2022—contaminating drinking water supplies and requiring the use of desalination . The United States Army Corps of Engineers constructed "saltwater sills" or "underwater levees" to contain this in 1988, 1999, 2012, and 2022. This consists of

4067-415: The basin in increasing numbers. The river served sometimes as a barrier, forming borders for New Spain , New France , and the early United States, and throughout as a vital transportation artery and communications link. In the 19th century, during the height of the ideology of manifest destiny , the Mississippi and several tributaries, most notably its largest, the Ohio and Missouri , formed pathways for

4150-411: The country. This is reflected in the Gateway Arch in St. Louis, which was designed to symbolize the opening of the West, and the focus on the " Trans-Mississippi " region in the Trans-Mississippi Exposition . Regional landmarks are often classified in relation to the river, such as "the highest peak east of the Mississippi " or "the oldest city west of the Mississippi". The FCC also uses it as

4233-427: The course of the river, this gives an overall average of around 26 mi (42 km) per day, or 1 mi (1.6 km) per hour. The stream gradient of the entire river is 0.01%, a drop of 450 m over 3,766 km. The Mississippi River discharges at an annual average rate of between 200 and 700 thousand cubic feet per second (6,000 and 20,000 m /s). The Mississippi is the fourteenth largest river in

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4316-513: The crystal structure of the quartz, known as Moss defects. Such defects are produced by tectonic deformation of the parent rock, and also arise from the high-low transition of quartz: Quartz experiences a sharp decrease in volume when it cools below a temperature of about 573 °C (1,063 °F), which creates strain and crystal defects in the quartz grains in a cooling body of granite. Mechanisms for silt production include: Laboratory experiments have produced contradictory results regarding

4399-403: The delta of the Chippewa River of Wisconsin as it enters the Upper Mississippi, is more than 2 miles (3.2 km) wide. By the time the Upper Mississippi reaches Saint Paul , Minnesota, below Lock and Dam No. 1, it has dropped more than half its original elevation and is 687 feet (209 m) above sea level. From St. Paul to St. Louis, Missouri, the river elevation falls much more slowly and

4482-532: The depth averages 50–100 feet (15–30 m) deep. The deepest part of the river is in New Orleans, where it reaches 200 feet (61 m) deep. The Mississippi River runs through or along 10 states, from Minnesota to Louisiana , and is used to define portions of these states' borders, with Wisconsin , Illinois , Kentucky , Tennessee , and Mississippi along the east side of the river, and Iowa , Missouri , and Arkansas along its west side. Substantial parts of both Minnesota and Louisiana are on either side of

4565-405: The dividing line for broadcast call-signs , which begin with W to the east and K to the west, overlapping in media markets along the river. Due to its size and importance, it has been nicknamed The Mighty Mississippi River or simply The Mighty Mississippi . The Mississippi River can be divided into three sections: the Upper Mississippi , the river from its headwaters to the confluence with

4648-483: The earthquake damage potential in the silty soil of the central United States in the event of a major earthquake in the New Madrid Seismic Zone . Silt is easily transported in water and is fine enough to be carried long distances by air in the form of dust . While the coarsest silt particles (60 micron) settle out of a meter of still water in just five minutes, the finest silt grains (2 microns) can take several days to settle out of still water. When silt appears as

4731-419: The effectiveness of various silt production mechanisms. This may be due to the use of vein or pegmatite quartz in some of the experiments. Both materials form under conditions promoting ideal crystal growth, and may lack the Moss defects of quartz grains in granites. Thus production of silt from vein quartz is very difficult by any mechanism, whereas production of silt from granite quartz proceeds readily by any of

4814-443: The fine silt produced in dust storms and the coarse silt fraction possibly representing the fine particle tail of sand production. Loess underlies some of the most productive agricultural land worldwide. However, it is very susceptible to erosion. The quartz particles in silt do not themselves provide nutrients, but they promote excellent soil structure , and silt-sized particles of other minerals, present in smaller amounts, provide

4897-441: The hotspot's activity declined, the crust beneath the embayment region cooled, contracted and subsided to a depth of 2.6 km, and around 80 million years ago the Reelfoot Rift formed a trough that was flooded by the Gulf of Mexico . As sea levels dropped, the Mississippi and other rivers extended their courses into the embayment , which gradually became filled with sediment with the Mississippi River at its center. Through

4980-401: The laboratory using the pipette method, which is based on settling rate via Stokes' law and gives the particle size distribution accordingly. The mineral composition of silt particles can be determined with a petrographic microscope for grain sizes as low as 10 microns. Vadose silt is silt-sized calcite crystals found in pore spaces and vugs in limestone . This is emplaced as sediment

5063-460: The largest drainage basin in the United States . From its traditional source of Lake Itasca in northern Minnesota , it flows generally south for 2,340 miles (3,766 km) to the Mississippi River Delta in the Gulf of Mexico . With its many tributaries , the Mississippi's watershed drains all or parts of 32 U.S. states and two Canadian provinces between the Rocky and Appalachian mountains. The river either borders or passes through

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5146-416: The largest in North America. Native Americans have lived along the Mississippi River and its tributaries for thousands of years. Many were hunter-gatherers , but some, such as the Mound Builders , formed prolific agricultural and urban civilizations, and some practiced aquaculture . The arrival of Europeans in the 16th century changed the native way of life as first explorers, then settlers, ventured into

5229-402: The last two decades, this number was only 160 million short tons (145 million metric tons) per year. The reduction in sediment transported down the Mississippi River is the result of engineering modification of the Mississippi, Missouri, and Ohio rivers and their tributaries by dams, meander cutoffs , river-training structures, and bank revetments and soil erosion control programs in

5312-437: The lower 10 miles (16 km) of the Kaskaskia River, forming a new Mississippi channel and cutting off the town from the rest of the state. Later flooding destroyed most of the remaining town, including the original State House. Today, the remaining 2,300 acres (930 ha) island and community of 14 residents is known as an enclave of Illinois and is accessible only from the Missouri side. The New Madrid Seismic Zone , along

5395-415: The lower Mississippi from shifting into the channel of the Atchafalaya River and bypassing New Orleans . Since the 20th century, the Mississippi River has also experienced major pollution and environmental problems — most notably elevated nutrient and chemical levels from agricultural runoff, the primary contributor to the Gulf of Mexico dead zone . The word Mississippi itself comes from Misi zipi ,

5478-549: The necessary nutrients. Silt, deposited by annual floods along the Nile River , created the rich, fertile soil that sustained the Ancient Egyptian civilization. The closure of the Aswan High Dam has cut off this source of silt, and the fertility of the Nile delta is deteriorating. Loess tends to lose strength when wetted, and this can lead to failure of building foundations. The silty material has an open structure that collapses when wet. Quick clay (a combination of very fine silt and clay-sized particles from glacial grinding)

5561-449: The new river channel, contiguous with the adjacent state. Also, due to a meander in the river, a small part of western Kentucky is contiguous with Tennessee but isolated from the rest of its state. Many of the communities along the Mississippi River are listed below; most have either historic significance or cultural lore connecting them to the river. They are sequenced from the source of the river to its end. The road crossing highest on

5644-425: The past 5,000 years, caused the coastline of south Louisiana to advance toward the Gulf from 15 to 50 miles (24 to 80 km). The currently active delta lobe is called the Birdfoot Delta, after its shape, or the Balize Delta , after La Balize, Louisiana , the first French settlement at the mouth of the Mississippi. The current form of the Mississippi River basin was largely shaped by the Laurentide Ice Sheet of

5727-453: The past 50 years. With Dutch funding, the Bangladeshi government began to help develop older chars in the late 1970s, and the effort has since become a multi-agency operation building roads, culverts , embankments, cyclone shelters, toilets and ponds, as well as distributing land to settlers. By fall 2010, the program will have allotted some 100 square kilometres (20,000 acres) to 21,000 families. A main source of silt in urban rivers

5810-436: The plume did not mix with the surrounding sea water immediately. Instead, it stayed intact as it flowed through the Gulf of Mexico, into the Straits of Florida , and entered the Gulf Stream . The Mississippi River water rounded the tip of Florida and traveled up the southeast coast to the latitude of Georgia before finally mixing in so thoroughly with the ocean that it could no longer be detected by MODIS. Over geologic time,

5893-440: The problem may be the conflation of high rates of production with environments conducive to deposition and preservation, which favors glacial climates more than deserts. Loess associated with glaciation and cold weathering may be distinguishable from loess associated with hot regions by the size distribution. Glacial loess has a typical particle size of about 25 microns. Desert loess contains either larger or smaller particles, with

5976-479: The river, although the Mississippi defines part of the boundary of each of these states. In all of these cases, the middle of the riverbed at the time the borders were established was used as the line to define the borders between adjacent states. In various areas, the river has since shifted, but the state borders have not changed, still following the former bed of the Mississippi River as of their establishment, leaving several small isolated areas of one state across

6059-502: The river, entangling the tug and several barges and halting river traffic for nine hours. Three barges broke loose and drifted downstream, missing Mark Twain Memorial Bridge . The bridge, then owned by Norfolk and Western Railway , predecessor of the current owner, was repaired. Built as a swing span , the bridge was converted in 1994 to a vertical lift bridge to increase the width of the navigational channel. The vertical lift span

6142-400: The site of the head of navigation of the river. The Upper Mississippi has a number of natural and artificial lakes, with its widest point being Lake Winnibigoshish , near Grand Rapids, Minnesota , over 11 miles (18 km) across. Lake Onalaska , created by Lock and Dam No. 7 , near La Crosse, Wisconsin , is more than 4 miles (6.4 km) wide. Lake Pepin , a natural lake formed behind

6225-524: The state line still follows the old channel. The town of Kaskaskia, Illinois once stood on a peninsula at the confluence of the Mississippi and Kaskaskia (Okaw) Rivers . Founded as a French colonial community, it later became the capital of the Illinois Territory and was the first state capital of Illinois until 1819. Beginning in 1844, successive flooding caused the Mississippi River to slowly encroach east. A major flood in 1881 caused it to overtake

6308-456: The states of Minnesota , Wisconsin , Iowa , Illinois , Missouri , Kentucky , Tennessee , Arkansas , Mississippi , and Louisiana . The main stem is entirely within the United States; the total drainage basin is 1,151,000 sq mi (2,980,000 km ), of which only about one percent is in Canada. The Mississippi ranks as the world's tenth-largest river by discharge flow, and

6391-699: The unaided eye. It also corresponds to a Tanner gap in the distribution of particle sizes in sediments : Particles between 120 and 30 microns in size are scarce in most sediments, suggesting that the distinction between sand and silt has physical significance. As noted above, the lower limit of 2 to 4 microns corresponds to the transition from particles that are predominantly broken quartz grains to particles that are predominantly clay mineral particles. Assallay and coinvestigators further divide silt into three size ranges: C (2–5 microns), which represents post-glacial clays and desert dust; D1 (20–30 microns) representing "traditional" loess ; and D2 (60 microns) representing

6474-567: The upper and lower river, the Mississippi is further controlled by thousands of wing dikes that moderate the river's flow in order to maintain an open navigation channel and prevent the river from eroding its banks. The head of navigation on the Mississippi is the St. Anthony Falls Lock. Before the Coon Rapids Dam in Coon Rapids, Minnesota , was built in 1913, steamboats could occasionally go upstream as far as Saint Cloud, Minnesota , depending on river conditions. The uppermost lock and dam on

6557-413: The very coarse North African loess. Silt can be distinguished from clay in the field by its lack of plasticity or cohesiveness and by its grain size. Silt grains are large enough to give silt a gritty feel, particularly if a sample is placed between the teeth. Clay-size particles feel smooth between the teeth. The proportions of coarse and fine silt in a sediment sample are determined more precisely in

6640-463: The western expansion of the United States. The river also became the subject of American literature , particularly in the writings of Mark Twain . Formed from thick layers of the river's silt deposits, the Mississippi embayment is one of the most fertile regions of the United States; steamboats were widely used in the 19th and early 20th centuries to ship agricultural and industrial goods. During

6723-473: The world by volume. On average, the Mississippi has 8% the flow of the Amazon River , which moves nearly 7 million cubic feet per second (200,000 m /s) during wet seasons. Before 1900, the Mississippi River transported an estimated 440 million short tons (400 million metric tons) of sediment per year from the interior of the United States to coastal Louisiana and the Gulf of Mexico. During

6806-496: Was chosen to designate the "true head" of the Mississippi River as a combination of the last four letters of the Latin word for truth ( ver itas ) and the first two letters of the Latin word for head ( ca put ). However, the lake is in turn fed by a number of smaller streams. From its origin at Lake Itasca to St. Louis, Missouri , the waterway's flow is moderated by 43 dams. Fourteen of these dams are located above Minneapolis in

6889-582: Was taken from a bridge over the Tennessee River at Florence, Alabama . To minimize the effect on river traffic, the new span was installed over the course of three days. Before the Mark Twain Memorial Bridge opened in 1936, the Wabash Bridge was also a toll bridge carrying U.S. Route 36 across the river. Mississippi River The Mississippi River is the primary river of

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