Back about '97 or '98 I read a paper (unfortunately, I've forgotten the author and journal, but I could probably hunt it up eventually) on bay rims in South Carolina. The researcher dated them to the P-H boundary (perhaps by Optical Stimulation Luminescense?). Formation of rims is pretty easy to understand. 12,000 to 10,000 years ago, most of North America was both colder and windier than it is now. There were still trees in South Carolina, but they would have been more thinly spread than today, sort of like a Savannah. Bays, being depressional areas, were wetter than the surrounding higher areas, and would have supported much denser stands of trees. These denser stands of trees acted like windbreaks; when wind slows down, it drops much of its aeolian load, and indeed, the thickest portions of bay rims are along the southeastern edges of bays, which would have been in the lee of prevailing winter winds. (This is similar to snow drifts forming on the lee side of a hedge or fence). The woody vegetation in bays was (and is) different from that of the surrounding upland areas, too; deciduous evergreens like Red Bay, Loblolly Bay, Sweet Bay, Dahoon, Ti-Ti, etc, while the vegetation on the uplands was dominantly oak-hickory...trees that would lose their leaves during the winter. The Bays were very effective windbreaks.
As for the ages of bays themselves, I think that was from a paper by Ray Daniels and Ehrling Gamble circa 1967. The copies weren't mine, they belonged to one of my colleagues, so it would take me some effort to track them down.
IOW, the bays walk, look and act like a duck to the layman(that would be me), that is, it looks for all the world like something took a swipe at the eastern seaboard(amongst other places???) at roughly the P/H boundary. If you're sayin' it ain't a duck, the arguments will necessarily have to be ironclad. Or maybe handed down from the mount. Coulda's and woulda's are great for purposes of discussion, but.....
Again, you'll forgive my skeptcism???
FS