Oh, I have that. Covered my septic system with it last summer. I almost cried, haha. Thought you had the the ancient tundra peat+evergreen in layers. Black like charcoal, basically the early stages of charcoal.
I thought he was sitting on black humus because of his location, but it sounds more like super fresh wood litter that the microbes have barely started on.
But yes, I was referring to the black soil you hear about. The smell is so rich. It's like perfume to a grower.
Look up Ancient Forest amendment.
View attachment 848968
Around $35 for .5ft cu.
Mix that with Fox Farm Ocean Forest, Roots Organic soil, and expanded clay pellets for super soil.