The Big Ones: How Natural Disasters Have Shaped Us (and What We Can Do About Them)

by Lucy Jones

Because we live on land, we tend to make an existential distinction between what appears at the surface and what is submerged beneath our rivers, lakes, and oceans. But a river is not fundamentally different from the land around it. There is no distinction in the types of earth that form the riverbanks, nothing unique about the crust that lies beneath it. It is simply lower lying than the areas around it. Water flows down to wherever gravity pulls it, so, inevitably, bodies of water form at those areas of lower elevation. This is stating the obvious, but it’s a truth we tend to lose sight of. The Mississippi River is where it is because the land beneath it is at a lower elevation than nearly all the land surrounding it. In fact, for the last 450 miles of the Mississippi, the riverbed is actually below sea level. (As it approaches New Orleans, the bed of the Mississippi is as low as 170 feet below sea level.) The upper parts of the water continue downhill and with friction pull the rest of the water with them. It makes for a turbulent passage.