Question about Mediterranean Sea formation & Flood

[supery00n]

Hey guys...I have a question about whether you think the following article on Wikipedia that describes the Messinian Salinity Crisis and its termination in the Zanclean Flood is valid. This refers to the drying out of and subsequent refilling of the Mediterranean Sea.

In 1920, H. G. Wells published a popular history book in which it was suspected that the Mediterranean basin had in the past been cut off from the Atlantic. One piece of physical evidence, a deep channel past Gibraltar, had been noticed. Wells estimated that the basin had refilled roughly between 30,000 and 10,000 B.C.[40] The theory he printed was that:[40]

• In the last Ice Age, so much ocean water was taken into the icecaps that world ocean level dropped[citation needed] below the sill in the Strait of Gibraltar.
• Without the inflow from the Atlantic the Mediterranean would evaporate much more water than it receives, and would evaporate down to two large lakes, one on the Balearic Abyssal Plain, the other further east.
• The east lake would receive most of the incoming river water, and may have overflowed into the west lake.
• All or some of this seabed may have had a human population, where it was watered from the incoming rivers.
• There is a long deep submerged valley running from the Mediterranean out into the Atlantic.
• (Modern research, however, has shown that Wells' theory is incorrect. All the geological and plant-fossil evidence shows that the Mediterranean did not dry out during the last ice age. Sea levels were 120m lower than today, resulting in a shallower Strait of Gibraltar and a reduced water exchange with the Atlantic, but there was no cut-off.[41])

I think the last bullet point that says that the Mediterranean Sea could not have been cut off from the Atlantic Ocean during the last Ice Age is an unjustified conclusion, and I present a counterexample to show this:

First of all, the claim that the Strait of Gibraltar is today, at its deepest point, 900m below present-day sea level is entirely true. But the claim that given that the sea level was 120m lower during the last Ice Age, the Strait of Gibraltar would still be below the waterline (900m - 120m) by 780m at its deepest point during the Ice Age is, while seemingly a perfectly rational conclusion, in actuality contains a subtle assumption.

Here's the counterexample:

Imagine that the Strait of Gibraltar was 10m above the sea level 20,000 years ago, and that it was an isthmus which was rather narrow, and further, that this above-sea level isthmus had remained above the sea level for a time period of greater than 1,000 years, which is the amount of time that is estimated to be needed to dry out the Mediterranean Sea into a basin given that it is blocked from the Atlantic Ocean.

Then the Mediterranean Sea would, at the time of 20,000 years ago, be a dry basin; further, not merely just reduced some 120m below its present level, but reduced either completely down to its deepest basins, or some amount far greater than just 120m; perhaps 2 km.

We know that the Mediterranean region near the Strait of Gibraltar, is, today, a very tectonically active region. The 1755 earthquake offshore of Lisbon Portugal, which had a moment magnitude of around 8.7, is an example of how large earthquakes close to magnitude 9 can happen near that region.

Because the Mediterranean Sea would be a basin in that situation, it would be supporting the entire mass of the ocean water on its west side (the Atlantic Ocean), and only air on its east side (because the water had dried out in the Mediterranean). Even given the increased atmospheric density on the right side due to the greater depths in the Mediterranean basin, the mass of water on the left hand side would still have a density of some 500 times greater than the air on the right hand side, and a pressure even greater.

So you have a disequlibrium of forces, since pressure is force over area, and the area exposed on both sides of the isthmus underwater are probably reasonably similar, yet a static situation. If this net force exerted on the isthmus' exceeds the breaking strength of the isthmus, and the breakage that results either occurs below the water surface, reduces the height of the isthmus above the then sea level from 10m above to something even like -5m above, the Atlantic Ocean will spill over that reduced height isthmus.

Let us assume that given such an disequilibrium of forces, an earthquake on the scale of the 1755 Lisbon quake (8.7 magnitude estimate), could potentially be a trigger event that reduces the tensile/breaking stress of the rock that makes up the isthmus so that the net force exerted on the isthmus, which was prior to the quake, insufficient to exceed the breaking stress of the isthmus, but now exceeds the breaking stress; not because the net force on the isthmus (i.e. the level of the ocean in the Atlantic increased, but because the earthquake caused the breaking stress of the isthmus rock to decrease...so that the unchanged net force suddenly "found itself" above the decreased breaking stress.

Then, the Atlantic Ocean would intrude into the Mediterranean basin. Perhaps even at a trickle at first, but scientists who worked on the Mediterranean Sea flood and studied the one 5.33 million years ago have done geophysical modeling that showed that a trickle would soon grow into a torrent.

This torrent would flow at a tremendous speed, which I argue would be sufficient to carve down what was prior to the earthquake+breakthrough of Atlantic water an isthmus into a deep U-shaped canyon. Since the sea levels 20,000 years ago were 120m below present day sea level and the hypothetical isthmus above-water I supposed was 10m above the then sea level of 120m, the isthmus would originally have been located at 110m (-120m + 10m) below present-day sea level, yet still NOT underwater (that's my supposition). The earthquake+incursion of water would then erode a total vertical distance of (-110m - (-900m)) = 790m, so that we now look at the present-day vertical maximum depth of the Strait of Gibraltar and say the water level never went down to 900m below present, so the Mediterranean couldn't have been cut off...but what if in actuality, the reason the strait is so deep today was because it did dry out 20,000 years ago as H.G. Wells hypothesized, and the ensuing flood that refilled it actually carved what was an isthmus 10m or so above the sea level of -120m all the way down to the present depth of -900 m (a total of 790m)?

Do you think this is a valid counterexample to the widely-held conclusion that the Mediterranean Sea could not have dried out during the last Ice Age?

Thanks.