The midwest has great soil because billions of organisms died millions of years ago in a shallow sea that covered most of the central united states today.
A theory I heard as a child was that glaciers pushed topsoil down from Canada during the ice ages? A superficial search did not turn up more info so maybe that has long been discredited and nobody told me.
I thought the soil was great because of the Yellowstone Caldera Supervolcano dropping huge amounts of volcanic ash every 650,000 years.
How long has it been? Oh, right around 650,000 years..........
You aren't wrong. All the life sustaining minerals/elements we have in the earths lithosphere are being renewed by volcanism. It is why the plant life was able to exist in the first place.
I’m not sure that’s correct, or at least is not complete. There were many cycles of grasses and wildlife involved in building up the soil.
No, it's correct. The plains states are so fertile because of hundreds of millions of years of shallow ocean water led to huge amounts of plankton to die and settle. That's also why there's oil in Texas, Oklahoma, and Kansas.