SOLVED!
The Answer to My Ig-runt Question From the Geology sub-Reddit (It was all because of that sneaky Upper Cretaceous Thank you "v7x" I'm a Selma chalk smiley face! I was once the coast of the Gulf of Mexico, long time ago. Even More The fertile soil has origins in the Cretaceous Period, when the shoreline of the Gulf of Mexico was much farther inland. Over millions of years, plankton that lived in the Gulf left behind exoskeletons rich in calcium carbonate—the accumulation of which resulted in the Black Belt’s chalk subsoil. As a result of all the calcium, the soil is very fertile and good for growing crops. I truly appreciate the response. Now we know. ("We" means quite a few of us'ns.) MacGown, Brown and Hill