Comment: 11:45 - 13:01 (01:16)
Source: Annenberg/CPB Resources - Earth Revealed - 20. Running Water II: Landscape Evolution
Keywords: "Mississippi River", river, "river channel", sea, sediment, discharge, bank, flood, "Gulf of Mexico", levee, commerce, "stream course"
Our transcription: The Mississippi could not have created this much land if it had stayed in one channel.
The southern part of the River has changed course many times over an area some 300 kilometers wide.
The key to these changes is the River's natural tendency to follow the "path of least resistance," which is almost always the shortest route to the sea.
The Mississippi follows a single channel until gradually its channel fills with sediment.
At that point, the River easily overtops its banks during periods of high discharge.
When that happens, it is free to find a more direct route to the Gulf, until of course, the lengthy cycle begins again.
This cyclical shifting of the Mississippi has resulted in an ongoing battle to control the forces of nature.
Along most of its lower course, levees have been built to confine the River to its present channel.
Cities and ports have grown along the Mississippi, and it has gradually become one of the world's most important economic waterways.
Geology School Keywords