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ATLANTIS & the Atlantic Ocean 1 (ORIGINAL)

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Author Topic: ATLANTIS & the Atlantic Ocean 1 (ORIGINAL)  (Read 36304 times)
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« Reply #15 on: December 21, 2007, 09:41:20 pm »


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   posted 08-10-2004 01:47 AM                       


                                                   Why Did The Med Dry Up?

25 June 2003 - Prof Victor Axiak*

Last week we had a collective dry nightmare of the Mediterranean Sea drying up. We saw how the stretch between Malta and Sicily was turned into a dusty plateau, with the occasional deep valley cutting through it. We also saw how both the Eastern and Western basins of this sea tuned into deep holes with vast expanses of salt flats alternating with occasional mountains. The climate within these dried up basins was very harsh and not many animal and plant forms were able to survive. On the other hand, the surrounding climate of the region is cooler and drier as an important moisture source disappeared.

The problem with this nightmare/dream is that it DID happen.



The first real indication of this cataclysmic past event came to light in 1970 when an international group of scientists started drilling the Mediterranean seafloor. Strange things started turning up in core samples: layers of microscopic plants and soil sandwiched between huge beds of salt more than two kilometres below today's sea level. The plants had grown in sunlight. Could the seafloor once have been near a shoreline? Or did the sea ever evaporated, leaving behind massive deposits of salts and what was once the sea floor, exposed to air! Eventually, most scientists agreed with the latter proposition: The Med did dry up. What’s more fantastic about this idea is that this sea probably dried up, only to be refilled with seawater more than once!

As we all know, the Mediterranean sea is exposed to intense sunlight which evaporates huge volumes of seawater. In fact, in spite of being replenished by a number of rivers which flow in it, some scientists have estimated that the sea level of our sea should go down by one metre every year, due to this water loss. So what stops this from happening? Well, this does not happen thanks to the Straits of Gibraltar through which water from the Atlantic is flowing in to compensate for the water loss due to the evaporation by the sun.

As the last Atlantic waters dripped over into the Mediterranean, this body of water began to become a hypersaline lake as evaporation exceeded precipitation and it eventually dried up (PICTURE 2). Prior to completely drying up, there could have been smaller hypersaline lakes, in which little or no marine life survived. As such lakes eventually evaporated as well, they left behind them thick deposits of salts. And these salt deposits were one of the first clues which suggested the possibility that our sea dried up, millions of years ago. Some remnants of these salt deposits today form salt mines which are commercially exploited (PICTURE 3)
About 5.3 million years ago, a small breach in the Gibraltar dam sent the process into reverse. Ocean water gushed out cutting a tiny channel to the Mediterranean. As the channel enlarged, the water flowed faster and faster, until the torrent ripped through the emerging Strait of Gibraltar at more than 100 knots. That must have been quite a sight (PICTURE 4)!

Eventually, the rising waters drowned the falls and warm Mediterranean water began to escape to the Atlantic, reheating the oceans and the planet. The salinity crisis ended about 5.3 million years ago. It had lasted roughly 600 000 years.
Incidentally, the pictures shown in the present contribution should not be taken literally or as being accurate enough. For example, it is quite likely that a few million years ago, the morphology of the Mediterranean was quite unlike that of today! However these pictures do give us a rough idea of what happened.

Can this event happen again? Yes. It is not unlikely that future continental drift will push the African continent closer to Europe sealing off the Straits of Gibraltar yet again.

Can it happen in our lifetime?

Certainly not.

These events are of a geological nature and therefore normally take place at VERY SLOW rates. So, it is quite likely that the human species will not be around to witness a repeat performance of this event.

What a pity!
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