How the Mediterranean Sea came to be“I recently learned something mindblowing about the geological history of the Mediterranean Sea, and I just can't get it out of my head.
Now I'm going to make it *your* problem too. Sorry.
Hang onto your hat. This is wild.
1/
This is the Strait of Gibraltar, where Europe and Africa reach out to *almost* touch each other.
At this point there's only 13 km/ 8 miles between them - and it's where the Med feeds into the Atlantic.
Imagine if something absurdly Roland-Emmerichy happened & it closed up?
⬇️
2/
No need to imagine - because it actually did.
It's called the Messinian Salinity Crisis, and it happened around 5-6 million years ago:
https://en.wikipedia.org/wiki/Messinian_salinity_crisis After a presumably colossal tectonic shift, the Pillars of Hercules closed (or more correctly were bridged)....
3/
...and the Mediteranean started drying up.
After some undetermined period of time, the Mediterranean was empty - evaporated down to a desert & a series of huge, super-salty lakes.
A vast, salty desert bowl - *kilometres* deep.
(This is not the wild thing.)
4/
The desert bowl of the western Med was also noticeable higher than the east.
You can see this in modern sea floor maps: shallower continental crust in the west, deeper oceanic in the east - connected at the modern-day Strait of Sicily...
And primed for another cataclysm.
⬇️
5/
Before I read about this, I assumed that at some point the Strait of Gibraltar cracked, the water rushed in, and over centuries or millennia, our modern Mediterranean was created.
That's a manageable thought, right? Epic in scale, but - thinkable.
That's not what happened.
6/
Modern borehole and siesmic data has uncovered huge grooves through the rock on either side of the Gibraltar Strait - each around 250 metres deep...
And there's a channel along the bed of the sea floor, carved with unimaginable force.
It's around 200km long.
7/
At some point, maybe after a massive earthquake, the landlocked cliffs at the Strait were forced aside and the Atlantic rushed in with *mindboggling* fury.
Not a waterfall, but a long slope - down which roared up to *100 million cubic metres of water a second*.
8/
I'm keeping the nerdy geological details pretty light here. There's so much, and it's all on an incredible, mindbending scale.
If you want to geek out further, I'll have a newsletter on all this next week. Sign up for free here:
everythingisamazing.substack.com
OK, back to it.
9/
This flood, descending a kilometre to the sea floor, had a thousand times the discharge of the modern Amazon...
And it refilled 90% of the West Med in a YEAR.
This was 5 (or 6) million years ago. Did any of our distant ancestors see it?
Can you imagine their terror?
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(One year. Or perhaps even less time. Or perhaps a couple of years!
(The point here is: this DIDN'T take centuries, or even decades. It was terrifyingly fast.
(It must have seemed like the end of the world.)
11/
If you're disappointed that the breached Straits of Gibraltar didn't form a spectacular waterfall - look to the east of this artist's reconstruction, courtesy of Wikipedia.
Remember that the eastern Med is a lot deeper?
South of Sicily, there's an underwater cliff...
⬇️
12/
The flood roared over it at around 160 miles an hour, forming a waterfall over 1.5km high.
And to the east, the deeper desert bowl of the dessicated Mediterranean started filling with water - rising up to 10 metres a day.
*Not* a typo.
13/
The name for this astounding event is the ZANCLEAN MEGAFLOOD:
https://en.wikipedia.org/wiki/Zanclean_floodI've put it in All Caps because, what a hilariously epic name. I burst out laughing when I read it.
Anyone searching for a name for their new rock band?
14/
So now I'll leave you to do your own reading - although, if you want my own excitable take on all this, I'll have something in my newsletter next week (everythingisamazing.substack.com/about)
And also? Let me say this very loudly:
AS YOU CAN SEE, GEOLOGY IS NOT BORING.”
From:
https://threadreaderapp.com/thread/1491080740586782720.htmlOr
https://twitter.com/mikeachim/status/1491080740586782720XKCD did a fantastic piece centered around people observing this event. It was super cool, published a frame at a time in like 30 minute increments
https://en.wikipedia.org/wiki/Time_(xkcd)
https://twitter.com/math_vet/status/1491211079523119112Zanclean Flood of the Mediterranean in Sicily - computer animation2 min