#4: The Shifting Landmass of the Mississippi River Delta
Look at enough old maps of southern Louisiana and the shoreline begins to resemble a disappearing sketch. The Mississippi built its delta by flooding, changing channels, and spreading sediment across broad wetlands. Levees now keep the river from wandering into communities and shipping routes, but they also prevent much of that mud and sand from replenishing sinking marshes. Meanwhile, buried sediment compacts under its own weight, canals alter water movement, salt reaches farther inland, hurricanes tear through fragile vegetation, and sea level continues rising around the land.
