In order to preserve a biblical claim, he rejects the clear evidence of far more mundane origins for the biblical flood story.
While I am inclined towards the "far more mundane origins" (and perhaps even Glenn Morton is), it is his here effort to fuse worldly history with Biblical claims. A real, major flood that happened at about the same time as earliest hominid history.
Now, I don't recall what Glenn's opinions about the ark are, but I'm very much inclined to think the whole ark concept is silly. Would all (or even much) of humanity and the Earth's creatures of that time be living within the Mediterranean basin? I don't think so. Also, for the ark to land on Mt. Ararat (Turkey) would require much more than the Mediterranean flood.
A more serious criticism arises from the lack of any method to carry the tale across 5 million years, call it 250,000 generations of pre-literacy with no assurance of even the capability of an oral tradition.
Now, in the context of a powerful creator God, I don't see this as a problem. God could have relayed the history of the flood to Moses lo those millions of years later (I'm serious, this isn't the sarcasm mode).
Professor, geology, Whatsamatta U
Evolution - Changes in the environment, caused by the interactions of the components of the environment.
"Do not meddle in the affairs of cats, for they are subtle and will piss on your computer." - Bruce Graham
"The modern conservative is engaged in one of man's oldest exercises in moral philosophy; that is, the search for a superior moral justification for selfishness." - John Kenneth Galbraith
"I know a little about a lot of things, and a lot about a few things, but I'm highly ignorant about everything." - Moose