A leaf falls in the water. A crawfish eats it. Larger fish eat the crawfish. Humans eat the larger fish. A flood wipes out human towns but leave nutrients behind to enrich the soil.
New plants grow.
They drop their leaves. And life on the Mississippi goes on. The Cahokia Mounds State Historic Site is the largest prehistoric settlement in North America. The Upper Mississippi National Wildlife Refuge is a haven for migratory birds, waterfowl, and raptors. The refuge stretches 264 miles along the river in Minnesota, Wisconsin, Iowa, and Illinois.