Albert Barnes Commentary Genesis 7:17-24

"And the flood was forty days upon the earth; and the waters increased, and bare up the ark, and it was lifted up above the earth. And the waters prevailed, and increased greatly upon the earth; and the ark went upon the face of the waters. And the waters prevailed exceedingly upon the earth; and all the high mountains that were under the whole heaven were covered. Fifteen cubits upward did the waters prevail; and the mountains were covered. And all flesh died that moved upon the earth, both birds, and cattle, and beasts, and every creeping thing that creepeth upon the earth, and every man: all in whose nostrils was the breath of the spirit of life, of all that was on the dry land, died. And every living thing was destroyed that was upon the face of the ground, both man, and cattle, and creeping things, and birds of the heavens; and they were destroyed from the earth: and Noah only was left, and they that were with him in the ark. And the waters prevailed upon the earth a hundred and fifty days." — Genesis 7:17-24 (ASV)

The prevalence of the waters. The forty days are now completed. At the end of this period, the ark had been afloat for a long time. It was drifted on the waters in the direction in which they were flowing, and toward what was formerly the higher ground (Genesis 7:19).

Upon the land. The land is to be understood as the portion of the earth’s surface known to humanity. This, with an unknown margin beyond it, was covered with the waters. But this is all that Scripture warrants us to assert. Concerning the distant parts of Europe, the continents of Africa, America, or Australia, we can say nothing.

All the high hills were covered. Not a hill was above water within the horizon of the spectator or of humanity. There were ten generations from Adam to Noah inclusive. We cannot tell what the rate of increase was.

But, supposing each couple to have ten children, and therefore the common ratio to be five, the whole number of births would be about five million, and the population in the time of Noah less than four million. It is probable that they did not scatter further than the necessities and conveniences of life demanded. In a fertile region, an area equal to that of the British Isles would be amply sufficient for four million men, women, and children.

Let us suppose, then, a circle of five hundred miles in diameter inhabited by people. Let this occupy the central region of a concentric circle of eight hundred miles in diameter. With a center a little southwest of Mosul, this larger circle would reach fifty miles into the Mediterranean, the Euxine, and the Caspian, and would probably have touched the Persian Gulf at the time of the deluge. If this region were covered with water, it is obvious that no land or mountain would be visible to a spectator within the inner circle of five hundred miles in diameter.

Fifteen cubits upward. This was half the depth of the ark. It may have taken this draft of water to float it. If so, its grounding on a hill under water would indicate the depth of water on its summit.

The gradual rise of the waters was accomplished by the depression of the land, aided, possibly, by a simultaneous elevation of the bed of the ocean. The water, by the mere necessity of finding its level, overflowed the former dry land.

The extent of this oscillation of the solid crust of the earth is paralleled by the changes of level that geology indicates, the last of which took place at the time of the six days’ creation. It is possible that most of the land that was then raised was now again temporarily submerged in the returning waters, while distant continents may have all along existed, which never came within the awareness of antediluvian humanity. The sobriety and historical veracity of the narrative are strikingly exhibited in the moderate height to which the waters are said to have risen above the ancient hills (Genesis 7:21–23).

There expired all flesh. The resulting death of all by drowning is recounted here. All in whose nostrils was the breath of the spirit of live died. This statement refers solely to humankind, whose higher life is exclusively expressed by the phrase חיים נשׁמת (nı̂shmat chayı̂ym), “breath of life” (Genesis 2:7). It affirms the death of all humankind. The sum total of animal and vegetable life, with the exception of those in the ark, is declared here to be extinguished.

Fifty and a hundred days (Genesis 7:24). These, and the forty days of rain, make one hundred and ninety days: about six lunar months and thirteen days. If to this we add the month and seventeen days before the commencement of the rain, we have eight months completed, and are therefore brought to the first day of the ninth month. The waters may be said to prevail as long as the ark had its full draft of water. It is probable they were still rising during the first half of the one hundred and fifty days, and then gradually sinking during the other half.