To those of you who are new visitors, my goal with this blog is to discover and write about the complex relationships between ecology and society. The maps of black belt soils and voting patterns were a particularly elegant and striking example of the sort of geographic connections I'm fascinated by. If you liked that post, you should also check out Portlandhenge, the Downtown Portland Glacier, From Swimming Pools to Vernal Pools, and The ExxonMobil Arena/Disaster Shelter.
Red soil in red counties: Commenter Michael, in the Black Belt post below, pointed out that "as you travel into the politically red areas, it's also literally red, as river sediments give way to red clay. My guess is that the red dirt isn't nearly as good for farming."
I did some background research on this and found that it's true. Actually, the black belt itself features a good deal of red clay, but it's underneath a surface layer of rich, black and loamy topsoil. The photo at right shows a sample of "Bama soil," the official state soil of Alabama. Note the thinner layer of black soil on top of a thicker layer of red, iron-rich clay.
Clay soils are typically the remnants of ancient marine sedimentary deposits, so naturally, there's a lot of clay in the Black Belt and just to its south. But this essay from the Alabama Dept. of Conservation explains that black belt soils have a thicker layer of black, more fertile topsoil because of its chalk content. The chalk fostered prairie grasses, which, over millions of years, accumulated into a dark, nutrient-rich topsoil. South of the Black Belt, where the Cretaceous seas were deeper, there's less chalk. Which means less fertile soil. Which means they supported fewer antebellum slave plantations. Which means more Republicans live there today.
But their gardens are probably lousy.