Chris wrote (to Don):

Genesis is the creation myth of the ancient Near East assimilated by the Hebrews and reinterpreted in the light of their experience of God. In fact two or three myths went into Genesis and were combined to make an almost coherent whole. Any good commentary will tell you this. It may or may not contain cultural memories of a large flood which covered the whole Middle East, which may or may not have been related to a sudden sea level rise of up to 80 metres possibly caused by the rapid melting of the Greenland ice sheet (to inject some science!).

Chris