The shell midden I'm linking to is much, much more recent, but I do wonder if something like a buried-in-sediment offshore midden of similar type is the sort of

The shell midden I'm linking to is much, much more recent, but I do wonder if something like a buried-in-sediment offshore midden of similar type is the sort of evidence that would could theoretically find (relatively) easily if we started looking at submerged historic coastline in earnest. https://en.wikipedia.org/wiki/Whaleback_Shell_Midden https://en.wikipedia.org/wiki/Whaleback_Shell_Midden