When the what whatted?! Here we go again with one of our goofy titles. How can we be serious about this sort of thing? You know we are just trying to get your attention. Right? Well, it worked, didn’t it? (And it’s about time you started reading these columns!) But there is a real story here and a good one. It all started back in the early 1970’s. Geologists on the Glomar Challenger, a deep-sea research vessel, had been drilling in the Mediterranean and they made some very surprising discoveries. Pretty much everywhere they drilled, they encountered salt deposits - thick salt deposits. They interpreted those salts as having been formed during successive moments when the Mediterranean Sea had dried up or at least almost dried up. Yep, that’s quite the claim, isn’t it? Once again, we have some explaining to do.
The story begins during the last ten or so million years. Africa had been drifting to the north and a collision with Europe was resulting. This was a bit of a bumpy ride. When Africa made enough of an advance the Strait of Gibraltar was likely to close. If Africa backed up, then the strait was likely to open. During any of those closures the Mediterranean Sea was cut off from any access with the North Atlantic. In fact, it was isolated from all other bodies of water. Well, you might think “so what” how could the Mediterranean actually dry up? Much of it is more than three miles deep. That’s a lot of water. That just doesn’t seem possible, or even plausible, and certainly not intuitive. But it is, in fact, quite possible; this is a pretty dry region. The Sahara Dessert is just to the south and the arid Mid East is just to the east. It has been calculated that all that water would evaporate in only about a thousand years.
This awful time has a name; it is called the “Messinian Salinity Crisis.” As we said, this was a bumpy ride. The Strait of Gibraltar opened and closed several times. The first was about six million years ago, that’s the time called the Messinian. Imagine flying a plane west to east across the Mediterranean back then. Down below there would have been gigantic salt flats, gleaming white in the subtropical sun. Here and there you would see relatively small basins of hyper-salty waters, each a lot like today’s Dead Sea.
Watching an ocean dry up would not have been very exciting. But when the Strait opened up again it must have gotten real interesting Think about it and, in your mind’s eye, imagine the waters of the North Atlantic pouring through the Gibraltar Strait and refilling the Mediterranean with those three miles of sea water! We wish that Frederic Church had been there to paint that waterfall!
Neither one of us spends much time reading science fiction. Can you guess why?
Contact the authors at randjtitus@prodigy.net. Join their facebook page “The Catskill Geologist.; Read their blog at “thecatskillgeologist.’
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