http://www.madere.com/history.htmlWith each flood, the Mississippi has also raised its banks or natural levees higher. At New Orleans, the natural levees average ten to fifteen feet above sea level and one to two miles in width, sloping gently and almost imperceptibly into the backswamp. So uninviting was the backswamp as a place to build, that for some 200 years New Orleans was confined to its natural levees of the Mississippi and the Metairie and Gentilly ridges. In southeast Louisiana, since only the natural levees are well-drained, relatively safe from flooding and allow the building of roads and structures, nearly all settlements, urban and rural, are located on the natural levees of the Mississippi and its distributaries.
While building its levees higher, the Mississippi extends then further into the Gulf. As it does so, the river also raises its riverbed higher. To maintain its current, the river requires a gradient. Whenever the current slackens, material is deposited in the riverbed. So, as the river extends itself into the gulf, its upstream stretches rise higher and higher with each new flood and each addition to the natural levees. Consequently, in many of its stretches in south Louisiana, the Mississippi stands higher than its adjacent flood plain. For this reason, all small streams in south Louisiana flow away from or parallel to the Mississippi's natural levees. Since none of the small streams can cross the Mississippi, intra-coastal shipping was impossible in the Mississippi's delta until a canal with locks was built in 1909. In the New Orleans area, the Mississippi stands ten to fifteen feet above sea level, perched on a ridge above much of the modern city.
Throughout its geologic history, the Mississippi has changed its course numerous times. The river's former main courses largely determined the pattern of modern settlement and transportation routes in southeast Louisiana. One, the Bayou Teche, is the main artery of Cajun Louisiana; its natural levees supporting such Cajun centers as St. Martinville, Breaux Bridge, New Iberia and Lafayette. Halfway between the Teche and New Orleans, Bayou Lafourche is a more recent ancestor of the Mississippi. The St. Bernard Delta, east of New Orleans, is another former course of the Mississippi. These former courses all run parallel to one another, but they are separated by swampy troughs. Until recently, all roads in southeast Louisiana were limited to natural levees and ran parallel to one another, which made travel in and through Cajun country difficult and left New Orleans poorly connected with its immediate hinterland.
Printer-friendly format
Email this thread to a friend
Bookmark this thread
(1000+ posts)
Send PM |
Profile |
Ignore
