Okay, when the flood came, men who had boats got into them. Those without boats would find something that floated and jumped onto it. Others started climbing hills and mountains. In these cases, when the flood finally took them, their bones would have been on the top layer of sediment, wouldn't you say?
Now be honest, if you lived in Noah's day, and it began to rain so your home, etc., were underwater, wouldn't you jump into or onto something that floated? If you did, I'm sure your bones would settle on top of the many giant dinosaur-type animals that could not climb, swim, or float. Six thousand years later, when they find your bones, they would say, "Hay look, Serk's bones are here; he must have floated on something or been on a boat for 39 days before his end came.