In existographies, universal flood, aka global flood or “flood myth”, refers to a large number of great deluges, all of which derive from the annual Nile River flood (see: Noah’s flood), a phenomenon occurring annual in Egypt, wherein, owing to the melting of snow in the Ethiopian mountains, waters would rise three stories in height, covering entire islands and homes, lasting for 150 days.

Quotes
The following are related quotes:

“Because the sea could not rise fifteen cubits, or one-and-twenty standard feet and a half, above the highest mountains, without leaving its bed dry, and, at the same time, violating all the laws of gravity and the equilibrium of fluids, which would evidently require a miracle.”
Voltaire (1764), Philosophical Dictionary (§:Deluge) [1]

“Because the physical impossibility of a universal deluge, by natural means, can be strictly demonstrated. The demonstration is as follows: All [72] the seas cover half the globe. A common measure of their depths near the shores, and in the open ocean, is assumed to be five hundred feet. In order that they might cover both hemispheres to the depth of five hundred feet, not only would an ocean of that depth be necessary over all the land, but a new sea would, in addition, be required to envelop the ocean at present existing, without which the laws of hydrostatics would occasion the dispersion of that other new mass of water five hundred feet deep, which should remain covering the land. Thus, then, two new oceans are requisite to cover the terraqueous globe merely to the depth of five hundred feet. Supposing the mountains to be only twenty thousand feet high, forty oceans, each five hundred feet in height, would be required to accumulate on each other, merely in order to equal the height of the mountains. Every successive ocean would contain all the others, and the last of them all would have a circumference containing forty times that of the first.”
— Voltaire (1764), Philosophical Dictionary (§:Deluge) [1]

See also
God character equivalents

References
1. (a) Voltaire. (1764). Philosophical Dictionary (§:Deluge) (txt). Publisher.
(b) Joshi, Sunand T. (2014). The Original Atheists: First Thoughts on Nonbelief (pg. 54). Prometheus Books.

External links
Flood myth – Wikipedia.
Genesis flood narrative – Wikipedia.
List of flood myths – Wikipedia.

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