- [Tweet](https://twitter.com/i/status/1491080740586782720) by [@Mikeachim](https://twitter.com/Mikeachim) on 2022-02-08 - - 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/ [pic.twitter.com/NGwwSsBhGb](https://twitter.com/Mikeachim/status/1491080740586782720/photo/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/ [pic.twitter.com/DcQHInaoai](https://twitter.com/Mikeachim/status/1491083081444655106/photo/1) - No need to imagine - because it actually did. - It's called the Messinian Salinity Crisis, and it happened around 5-6 million years ago: - [en.wikipedia.org/wiki/Messinian…](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/ [pic.twitter.com/BySQ2sjOw3](https://twitter.com/Mikeachim/status/1491087135214284801/photo/1) - 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/ [pic.twitter.com/6XL2vk5fZS](https://twitter.com/Mikeachim/status/1491089038694322176/photo/1) - 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](https://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? - 10/ [pic.twitter.com/TkkD1XXESy](https://twitter.com/Mikeachim/status/1491095871064141827/photo/1) - (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/ [pic.twitter.com/PbYtnFWnCS](https://twitter.com/Mikeachim/status/1491097445392334850/photo/1) - 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/ [pic.twitter.com/XVKbXPFNcy](https://twitter.com/Mikeachim/status/1491098962853777410/photo/1) - The name for this astounding event is the ZANCLEAN MEGAFLOOD: - [Zanclean flood - Wikipedia](https://en.wikipedia.org/wiki/Zanclean_flood) - I'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](https://everythingisamazing.substack.com/about)) - And also? Let me say this very loudly: - AS YOU CAN SEE, GEOLOGY IS NOT BORING. - Thanks for reading. :) - And lastly, since this is starting to go a bit nuts with shares & likes (thank you!) - you may also enjoy this thread I did in December, about light pillars: - [twitter.com/Mikeachim/stat…](https://twitter.com/Mikeachim/status/1466763517487370246) - Ta! - [@Xian_Yesu](https://twitter.com/Xian_Yesu) Ahhh - no, I *had* heard about it, via this podcast: [twitter.com/everywheretrip…](https://twitter.com/everywheretrip/status/1444754146372898817) And it had utterly fled my mind, like the fool I am... - Thank you for reminding me. :) - And! A hat-tip to [@frod_san](https://twitter.com/frod_san) for steering me towards this reconstruction of the Mediterranean flood: [twitter.com/frod_san/statu…](https://twitter.com/frod_san/status/1491168739609354241) - And and! [@math_vet](https://twitter.com/math_vet) reminded me that the Zanclean Megaflood featured in one of the finest things on the Web: [twitter.com/math_vet/statu…](https://twitter.com/math_vet/status/1491211079523119112) You really should check it out. It's a wonderful journey. - OK. Breaking from this Big Terrifying Geological Nope No Thanks theme for a second, I'd like to recommend to you some other curious, interested writers. - 1/ Mr [@douglasmack](https://twitter.com/douglasmack), a travel writer who now has a delightfully curious newsletter about snacks: [snackstack.net](https://www.snackstack.net/) - 2/ Jodi ([@legalnomads](https://twitter.com/legalnomads)) whose newsletter is the aptly-named Curious About Everything: [jodiettenberg.substack.com](https://jodiettenberg.substack.com/) - Read this just-published piece by her at CNN to learn what a terrific writer she is: [edition.cnn.com/travel/amp/jod…](http://edition.cnn.com/travel/amp/jodi-ettenberg-legal-nomads-csf-leaks-wellness-cmd/index.html) - 3/ The mighty [@celbrash](https://twitter.com/celbrash), ridiculously accomplished travel writer (recently in National Geographic) who can currently be found farming pearls in Tahiti: [kamokapearls.com](https://kamokapearls.com/) - Her daily life is ridiculously interesting (sorry, Celeste, but it's true). Follow her for the stories.