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Discovery of the Mississippi by De Soto A.D. 1541 by William Henry Powell depicts Hernando de Soto and Spanish Conquistadores seeing the Mississippi River for the first time. Map of the French settlements (blue) in North America in 1750, before the French and Indian War (1754 to 1763). c. 1681 map of Marquette and Jolliet's 1673 expedition.
The river runs approximately 273 miles (439 km) long, in the U.S. state of Illinois. [12] This river was important among Native Americans and early French traders as the principal water route connecting the Great Lakes with the Mississippi. The Illinois River meets the Mississippi at Pere Marquette State Park, which is near Grafton.
In addition, the length of meanders can change significantly over time due to natural or artificial cutoffs, when a new channel cuts across a narrow strip of land, bypassing a large river bend. For example, due to 18 cutoffs created between 1766 and 1885, the length of the Mississippi River from Cairo, Illinois , to New Orleans, Louisiana , was ...
The political and engineering focus in the 20th century was to separate the Lower Mississippi River from its floodplain.Levees and channelization—along with substantial loss of bottomland forests to agriculture in the alluvial valley—have resulted in a loss of wildlife and fish habitat, decreased water quality, and an expansion of the hypoxic zone in the Gulf of Mexico.
The shifting river delta at the mouth of the Mississippi on the Gulf Coast lies some 300 miles south of this area in Louisiana, and is referred to as the Mississippi River Delta. Rather, the Mississippi Delta is part of an alluvial plain , created by regular flooding of the Mississippi and Yazoo rivers over thousands of years.
Measure a length of stream, and mark the start and finish points. The longest length without changing stream conditions is desired to obtain the most accurate measurement. Place an orange at the starting point and measure the time for it to reach the finish point with a stopwatch. Repeat this at least three times and average the measurement times.
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. [7]
A temperature gradient is a physical quantity that describes in which direction and at what rate the temperature changes the most rapidly around a particular location. The temperature spatial gradient is a vector quantity with dimension of temperature difference per unit length. The SI unit is kelvin per meter (K/m).