[thedoc (OP)]

Jonathon Kent Robison  asked the Naked Scientists:































   































The Biblical 'Great Flood'is manifestly ludicrous for a variety of reasons, the purpose of which is to encourage people to fear 'God' and obey the BIble.































































For example, killing nearly every living thing would result in theskeletal remains of hundreds of millions of vetebrate animals at or close the surface.































































A Christian told me that it covered the tops of the mountains, butapart from the diffficuilty of climbers breathing at 29 000feet, wouldn't the water pushing the air up higher result in the gravity of the sun and moon further reducing the density of the atmosphere?































































Yours faithfully,































































Kent Robison.































































































What do you think?

[syhprum]

The general consensus is that the event that gave rise to the flood legend was the break thru of the Mediterranean sea into the depressed black sea raising its level by a hundred meters or so.
This took place over quite a long time and would have affected the rotational period of the Earth by a millisecond or so per day.

[RD]

Jonathon Kent Robison  asked the Naked Scientists:
... A Christian told me that it covered the tops of the mountains ...

Water did once cover almost everything on Earth ...

... the continents were mostly flooded until the end of the Archaean and that only 2–3% of the Earth's area consisted of emerged continental crust by around 2.5 Ga.

http://www.sciencedirect.com/science/article/pii/S0012821X08005748

[Pmb]

Water did once cover almost everything on Earth ...

That is impossible. Where on Earth did you get such an idea? The link you posted doesn't say anything like that. In fact the word water doesn't even appear on that page. It certainly doesn't talk about the period of time in which Noah's flood was supposed to have occured, i.e. about 6,000 years ago. Do you realize what the volume of water must be in order to cover the entire surface of the earth high enough to cover all the mountaints, including Mt. Everest? Where do you think all that water could have gone?

[Pmb]

The Biblical 'Great Flood'is manifestly ludicrous for a variety of reasons, the purpose of which is to encourage people to fear 'God' and obey the BIble.

Whether that is the purpose of the flood story or not is merely a matter of opinion. Since God promised never to do it again what possible reason does anyone have to fear God from that story? God is powerful enough to put fear into the hearts of man with no story at all. Personally I have no fear of God no matter what I believe about Him.

[Pmb]

This took place over quite a long time and would have affected the rotational period of the Earth by a millisecond or so per day.

Why do you think it would alter the rotational period by that much? There's no basis to believe such a thing.

[RD]

Water did once cover almost everything on Earth ...

That is impossible. Where on Earth did you get such an idea? The link you posted doesn't say anything like that.

The article I linked to says ...

continents were mostly flooded until the end of the Archaean and that only 2–3% of the Earth's area consisted of emerged continental crust by around 2.5 Ga.

http://www.sciencedirect.com/science/article/pii/S0012821X08005748

i.e. 97-98% of the Earth was covered with water 2.5 billion years ago, (which was before mountains like Everest existed ).

[Bored chemist]

Unless you only count man-made artefacts, I suspect that water still covers most things on earth.
If you suddenly borrowed a lot of water from somewhere an put it on earth you would make the earth more massive and that would tend to increase the surface air pressure, but not by much.
Also, you would displace all the air that's currently here up to the new "sea level" so the overall effect on air pressure would be fairly small.

Noah wouldn't have had much difficulty breathing while on the arc.
The big problems would have been the fact that his boat wasn't big enough and it would have been destroyed by the rainfall needed to create the flood.
That's how we know it didn't happen.
And that, in turn, is a good reason not to fear God- all the evidence in favour of His existence is shoddy or impossible.

[evan_au]

I don't think the (unchanged) gravity of the Sun or Moon would have an effect on the breathability of Earth's atmosphere.

[CliffordK]

Obviously water can not just appear from nothing, then disappear again just as quickly. 

However, undoubtedly early man experienced many floods so it would not be hard to imagine them making up stories about the biggest, worst flood possible.  And, as mentioned, at the beginning of the Holocene, there was a relentless increase in sea levels around the world, and in the Mediterranean Basin. 

If an island or small continent sunk, it could seem like the whole world was covered with water, and depending on the location, it might take some time before land was found once again.

If we experienced a movement of water from the poles to the equator at the beginning of the Holocene, it undoubtedly would have slightly slowed the spin of the planet. 

The density of the atmosphere is dependent on the elevation, but if the air is displaced from lower elevations, then for the most part, it will simply move upwards.  So, if the air pressure is about 1 ATM at sea level.  Then, if sea level increased by 100 feet, the air pressure would remain at about 1 ATM.  Perhaps slightly more complicated with the movement of polar ice to equatorial oceans, but the difference will remain minimal.

[alancalverd]

The OP asked about the gravitational consequences. The answer surely is "none". All the water was present somewhere and it just moved somewhere else, so the mass of the planet was unchanged. There may have been some local changes in g due to the redistribution of mass, but as far as the man in the moon was concerned, the mean gravitational attraction of the blue lump stayed the same. 

[yor_on]

Whatever happened I would expect it to have happened while we was around, to remember it. And without good communications something happening over a whole country may well be interpreted as including the whole earth I guess?