100% upvoted, but again lightly commented upon.

The general consensus of the black mat layer is that it represents a period of increased moisture (and hence increased plant matter) in what is now the desert Southwest.

Interesting, I can accept this hypothesis.

The black mats are a southwestern US phenomenon; they are not widespread across the country or anything.

Oh... the reply is either misinformed or disingenuous. I get it.

"At a conference later that year, my boss approached him and asked what he found in the samples. He said he had not run them yet. But then in a presentation later that day, he claimed to have nanodiamonds and microspherules from the Younger Dryas layer at our site. Shady as hell..."

Whoa, don't think you ever mentioned that before. Between that and the PNAS thing...

and

That is extremely illuminating. Shady indeed.

So, it seems the community liked that reply (+11) and didn't oppose it.