[Modernman]

I, for one, favor the idea that the biblical flood story (and the Gilgamesh story, as well as a lot of other ones) is the garbled hand-me-down of oral traditions concerning the great flood following the collapse of the great-lakes ice-wall at the end of the last glaciation.

It could be a little bit of both. Flood stories probably floated around in most cultures based on the end of the last ice age. At some point, the stories might well have been formalized, much like Homer (or a group of Greek poets) formalized the story of the Trojan wars.

[King Prout]

meaning... a more recent local flood may have caused an author or group to craft an epic about The Big Flood, cannibalizing bits and pieces of older tradition which were folklore concerning the flood at the end of the Ice Age?

makes sense.

impossible to determine either way, but makes sense.