The Flood Myth  
     The Biblical flood myth of Genesis has it's roots in earlier religions.  The Sumerian version, which predates the Bible by over a thousand years, and the Babylonian Epic of Gilgamesh, which is over two hundred years older than the Bible, and is likely the story the Bible's authors plagarized.
     The Gilgamesh story has the traditional elements of the Biblical myth.  A hero warned by a god,the building of a huge boat, animal selection, the ship grounding on a mountain, a sacrifice to please the god, and the god's promise to not do it again.  Sound familiar? The Mesopotanian deluge story even has the releasing of various birds to find dry land.
     Also note that the Hebrew word translated as earth also means land and country. The deluge was likely only a report of the writers known world or homeland. Common sense should tell us that there is no where near enough water on earth or in our atmosphere to cover all but the highest of mountain tops.