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.

Tuesday, April 2, 2024

Mysterious mountains

It's amazing how far human knowledge has come in only a hundred years.

Consider the following about the year 1924:

  • This is the year we would figure out that there are other galaxies beyond the Milky Way; before this, astronomers thought the Milky Way was all there was.  They called the galaxies they knew about (such as Andromeda and the Whirlpool Galaxy) "nebulae" (Latin for "clouds") and thought they were blobs of dust within our own galaxy.  This marks the moment we realized how big the universe actually is.
  • In 1924, the quantum nature of reality was still unknown; the first major papers by Heisenberg, Schrödinger, and Born would come out next year.
  • It'd be another four years before the first antibiotic -- penicillin -- was discovered.
  • It'd be five years before Edwin Hubble announced his discovery of red shift, which showed the universe is expanding and led to the Big Bang model of cosmology.
  • We'd have another seventeen years before we'd see the first electron micrograph of a virus; before that, it was known they caused disease, but no one knew what they were or had ever seen one.
  • It'd be another twenty years before DNA was shown to be the genetic material, and a good twenty years after that when Franklin, Watson, and Crick figured out its structure and the basics of how it works.
  • The first papers outlining the mechanics of plate tectonics were still forty years in the future; at this point, the only one who championed the idea that the continents moved was German geologist and climatologist Alfred Wegener, who was pretty much laughed out of the field because of it (and ultimately died in 1930 on an expedition to Greenland).

It's the last one that's germane to our topic today, which is a largely-unexplained (and massive) feature of North Africa that goes to show that however far we've come, there are still plenty of things left for the scientists to explain.  It's called the Tibesti Massif, and largely lies in the far north of the country of Chad, with a bit spilling over the southern border of Libya.

It's a strange, remote, and forbidding landscape:

[Image is in the Public Domain courtesy of photographer Michael Kerling]

What's peculiar about it -- besides the fact that it looks like the "desert planet" set from Lost in Space -- is that its terrain was largely created by volcanism, despite the fact that it lies smack in the center of one of those "stable continental cratons" I talked about in my previous post.  It's got a very peculiar geology -- the basement rock is Precambrian granite, over which there's a layer of Paleozoic sandstone, but above that is a layer of basalt which is in some places three hundred meters thick.  Basalt is one of those mafic rocks I mentioned; iron-rich, silica-poor, and ordinarily associated with seafloor rift zones like Iceland and deep-mantle hotspots like Hawaii.  But over that are felsic rocks like dacite, rhyolite, and ignimbrite, which are usually found in explosive, subduction zone volcanoes like the ones in the Caribbean, Japan, and Indonesia.

What's odd about all this is that there's no mechanism known that would generate all these kinds of rocks from the same system.  The current guess is that there was a mantle hotspot that started in the late Oligocene Epoch, on the order of twenty-five million years ago, that has gradually weakened and incorporated lower-density continental rocks as the upwelling slowed, but the truth is, nobody really knows.

It's still active, too.  The Tibesti Massif is home to hot springs, mud pools, and fumaroles, some of which contain water at 80 C or above.

So we've got a volcanic region in the southern Sahara where, by conventional wisdom, there shouldn't be one, with a geology that thus far has defied explanation.  Some geologists have tried to connect it to the Cameroon Line or the East African Rift Zone, but the truth is, Africa is a much bigger place than most people think it is, and it's a very long way away from either one.  (It's about three thousand kilometers from the northernmost active volcanoes in both Cameroon and Ethiopia to the southern edge of the Tibesti Massif; that's roughly the distance between New York City and Denver, Colorado.  So connecting Tibesti to either the Cameroon Line or the East African Rift is a bit like trying to explain the geology of Long Island using processes happening in the Rocky Mountains.)

And the problem is, figuring out this geological conundrum isn't going to be easy.  It's one of the most remote and difficult-to-access places on Earth, hampered not only by the fact that there are virtually no roads but the one-two punch of extreme poverty and political instability in the country of Chad.  So even getting a scientific team in to take a look at the place is damn near impossible.  The geologists studying the region have resorted to -- I swear I'm not making this up -- using comparisons to research on the geology of volcanoes on Mars, because even that is easier than getting a team into northern Chad.

The idea that we have a spot on the Earth still so deeply mysterious, despite everything we've learned, is both astonishing and thrilling.  Here we sit, in 2024, as arrogantly confident we have a bead on the totality of knowledge as the people did back in 1924, despite the fact that history has always shown such confidence in our understanding is unfounded.  The reality is humbling, and far more exciting.  As Carl Sagan put it, "Somewhere, something amazing is waiting to be known."

I wonder what the next hundred years will bring, and if the people in 2124 will look back at us with that same sense of "how could they not have known that?"

Onward -- into the great unknown!


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