"The Book of Genesis says of the Flood that 'all the high hills
that were under the whole heaven were covered'. Taken literally,
this seems to indicate that there were 10,000 to 20,000 feet of
water on the surface of the earth, eqiuivalent to more than half
a billion cubic miles of liquid! Since, according to biblical
accounts, it rained for 40 days and 40 nights, or for only 960
hours, the rain must have fallen at a rate of at least 15 feet
per hour."

John Paulous _Innumeracy, Mathematical Illiteracy and Its
Consequences_