The flood is depicted as having cosmic proportions and the telling uses universalistic rhetoric. Genesis is stronger in this regard than the Mesopotamian accounts. Tremper and John conclude: “The widespread nature of the destruction is indicated by the use of univeralistic rhetoric well-known for cataclysmic events, especially of a cosmic nature, in the ancient world.” (p. 71) The flood is longer in the biblical account than in the Mesopotamian accounts (forty days compared with seven days) but in all cases the numbers have rhetorical significance. They are not intended to convey specific details of an actual event.
“All of these are identifiably formulaic numbers that consistently carry rhetorical value. … the fact remains that the evidence from the ancient world and biblical usage indicates that we are not to read these time frames as specific or precise designations of actual time spans. We cannot reconstruct how long the rain lasted or the length of the aftermath of the flood from the information given; instead it is designed to convey the massive scope of the cataclysm.” (p. 71)