Hey, what if the darkearth was created using bloodletting ceremonies from across the Amazon? Sounds pretty odd, but blood is regenerative, and there were such ceremonies in South America. Am I nuts, or is this a possibility?
Methinks most of the blood-letting in mass quantities took place in Mexico (Aztecs). I don't recall similar activities on a large scale in the other Central and South America paleo-Indian cultures. Blam would probably know.
It should be pretty easy to tell by chemical analysis--such soil should have a high iron content.