Skeptophilia (skep-to-fil-i-a) (n.) - the love of logical thought, skepticism, and thinking critically. Being an exploration of the applications of skeptical thinking to the world at large, with periodic excursions into linguistics, music, politics, cryptozoology, and why people keep seeing the face of Jesus on grilled cheese sandwiches.

Thursday, October 5, 2023

A beautiful hellscape

One of the strangest places on Earth is in eastern Ethiopia.  Not that many people have even heard of it, for the very good reason that if you go there, there are about a million and one ways you could die.

It's called Dallol, which comes from a word in the Afar language meaning "disintegration."  The name comes from the fact that this is what would happen to you if you went for a swim there.  It lies in the Danakil Depression, and is a maze of hot springs, filled with water that gets up to 95 C and can have a pH of less than 1.  It's surrounded by evaporite plains covered with layers of magnesium, calcium, and iron oxide, crystalline salt, and elemental sulfur.

The place doesn't even look real:

[Image licensed under the Creative Commons Kotopoulou Electra, The hydrothermal system of Dallol, CC BY-SA 4.0]

The highest elevation in Dallol is 48 meters below sea level.  The region gets ridiculously hot -- think Death Valley in midsummer -- so tourism, even if you were so inclined, is pretty much out of the question.

Where it gets even more interesting is why, if the place is entirely below sea level, it's not under water.  And this has to do with the geology of the region, and how it was created in the first place.

Dallol and the Danakil Depression are part of the East African Rift System, which formed in the Miocene Epoch on the order of fourteen million years ago.  Basaltic magma upwelling from the mantle created a crack in the Earth's crust and began to fracture the African Plate.  This generated a long rift valley running more-or-less northeast to southwest, from the shore of the Red Sea in Ethiopia, under Lake Victoria, then southward through Tanzania and all the way to Malawi.  The entire thing is seismically active, but the north end especially so, experiencing nearly constant earthquakes and volcanic eruptions -- not to mention a huge amount of hydrothermal activity, such as you see at Dallol.

The water of the Red Sea is currently being held back by the barrier of the Erta Ale Range, which blocks the East African Rift Valley on its northeastern end.  Eventually, though, the barrier will be breached as the rift continues to open up, and the water will come pouring in.  At that point, all of Dallol and the Danakil Depression -- and a large part of the rest of the valley -- will be an inlet of the Indian Ocean.

That won't stop the rift from continuing to spread, though.  The entire "Horn of Africa" will separate from the rest of the continent and go sliding off to the east.  As I've pointed out before, it's only our short life spans that make us think the current configuration of continents is permanent.

For now, though, the Erta Ale Range is holding the ocean back, allowing us to take a look at one of the most inhospitable places on Earth.  What I find most curious is that a part of this same system of rifts -- farther south, in Kenya and Tanzania -- is thought to be the cradle of humanity.  Much of the history of our earliest ancestors, species like Paranthropus and Australopithecus and Ardipithecus, took place here.  Somehow they dealt with the heat and drought and seismic activity (as well as the predators), surviving long enough to evolve into Homo sapiens, who then pretty much rushed out and took over the whole planet.

Odd to think that a beautiful hellscape was where humanity first got its start.


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