Albert Barnes' Bible Commentary
Genesis 7:17-24
The prevalence of the waters. The forty days are now completed. And 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.
Upon the land. - The land is to be understood of the portion of the earth’s surface known to man. 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 man. 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 man. 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 draught 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 which 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 ken of antediluvian man. 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.
There expired all flesh. - The resulting death of all by drowning is here recounted. “All in whose nostrils was the breath of the spirit of live died.” This statement refers solely to man, whose higher life is exclusively expressed by the phrase חיים נשׁמת nı̂shmat chayı̂ym, “breath of life” Genesis 2:7. It affirms the death of the whole of mankind. The sum total of animal and vegetable life, with the exception of those in the ark, is here declared to be extinguished.
Fifty and a hundred days. - 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 draught of water. It is probable they were still rising during the first half of the hundred and fifty days, and then gradually sinking during the other half.