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Earth Science

Large Crack in East African Rift is Evidence of Continent Splitting in Two (pbs.org) 81

Posted by msmash from the closer-look dept.
A large crack, stretching several miles, made a sudden appearance recently in south-western Kenya. The tear emerged after heavy rains caused havoc in the nation last month, which also saw neighborhood get flooded and major highways closing off. The downpour also exposed a fault line that geologists now say is evidence that the African continent will split into two over the next tens of millions of years. From a report: The Earth is an ever-changing planet, even though in some respects change might be almost unnoticeable to us. Plate tectonics is a good example of this. But every now and again something dramatic happens and leads to renewed questions about the African continent splitting in two. The Earth's lithosphere (formed by the crust and the upper part of the mantle) is broken up into a number of tectonic plates. These plates are not static, but move relative to each other at varying speeds, "gliding" over a viscous asthenosphere.

[...] The East African Rift Valley stretches over 3,000km from the Gulf of Aden in the north towards Zimbabwe in the south, splitting the African plate into two unequal parts: the Somali and Nubian plates. Activity along the eastern branch of the rift valley, running along Ethiopia, Kenya and Tanzania, became evident when the large crack suddenly appeared in south-western Kenya. When the lithosphere is subject to a horizontal extensional force it will stretch, becoming thinner. Eventually, it will rupture, leading to the formation of a rift valley. This process is accompanied by surface manifestations along the rift valley in the form of volcanism and seismic activity. Rifts are the initial stage of a continental break-up and, if successful, can lead to the formation of a new ocean basin.
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Large Crack in East African Rift is Evidence of Continent Splitting in Two More

Large Crack in East African Rift is Evidence of Continent Splitting in Two

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  • Might be a good thing (Score:5, Interesting)

    by Spy Handler ( 822350 ) on Monday April 02, 2018 @12:55PM (#56367731) Homepage Journal

    Smaller landmasses surrounded by water tend to be nicer places to live than huge continents. For example, much of Pangaea's interior was a desert wasteland.

    • Doesn't seem that the landmass sizes will be even here. But still, good to know that we'll have a place to go to when we retire! Assuming the immortality research goes well, of course.

  • Really Slow News Day! (Score:4, Insightful)

    by foxalopex ( 522681 ) on Monday April 02, 2018 @01:03PM (#56367777)

    It's funny how these are slow geologic process taking millions of years yet there's an article reporting on it like it was "suddenly" new news or unexpected. A few more cracks might open in our lifetime but don't expect to see the "parting or the red sea" type movement in our lifetime. Most geological processes are super slow.

    • Re:Really Slow News Day! (Score:5, Insightful)

      by froggyjojodaddy ( 5025059 ) on Monday April 02, 2018 @01:18PM (#56367853)
      In the submitters (and many news outlets) defence, I would think for the majority of people, this was indeed 'sudden news'. Most people understand plate tectonics but that doesn't take away the newsworthiness of a huge crack opening up.

      Think of volcanoes (volcano's?). Most folks understand they exist and, on occasion, they erupt - maybe even that eruptions are inevitable, but it's still news when it does blow.

      I think even if the crack was a few mm wide, if it's any significant length or depth, it'd still be counted as interesting news.
    • But... when it does happen ... when the rift reaches the mediterranean ... what a sight it will be! Man!!! So sad I won't live to see it.

      The Gibraltar isthmus becoming Gibraltar straits happened just 12,000 years ago, missed it by a whisker. This flooding of the rift valley into a sea will take at least 1 million years they say...

      • Re: (Score:1)

        by Anonymous Coward

        Yes, the world we know today was 'created' 12.000 years ago by some very dramatic events by the looks of it, recommend Randall Carlson on the Joe Rogan show. https://www.youtube.com/watch?v=G0Cp7DrvNLQ
        In Northern Europe there has also been the world largest landslide with accompanying tsunamis:
        https://www.britannica.com/topic/Storegga-slides
        "scientists contend that one or more tsunamis associated with the Storegga slides washed away the land bridge connecting the island of Great Britain with continental Eur

      • Re: (Score:2)

        by Hadlock ( 143607 )

        San Francisco Bay by many accounts is only 10,000 years old; previously it was meadows and fields before it sunk and became flooded as a tidal estuary when sea levels rose.

      • If you're referring to the Zanclean flood [wikipedia.org], that is supposed to have happened more than 5,000,000 years ago. Also, Wikipedia says it may have taken 10,000 years for the Mediterranean to fill up.

      • This flooding of the rift valley into a sea will take at least 1 million years they say...

        It'll take a lot longer than that, since most of the East African Rift System is actually above sea level. Some of the lake bottoms go below sea level, but they're already full of water.

        when the rift reaches the mediterranean

        Very unlikely to happen - the rift is already veering towards the Arabian Sea at the Afar Triangle. While there is probably some geotectonic control over the direction of the lower 2500km of the Ni

    • Re: (Score:1)

      by Anonymous Coward

      Most geological processes are super slow.

      Most, yes. But not all... e.g. Missoula Floods (https://en.wikipedia.org/wiki/Missoula_Floods)

    • Re:Really Slow News Day! (Score:4, Informative)

      by radarskiy ( 2874255 ) on Monday April 02, 2018 @03:32PM (#56368885)

      It's a crack several miles long that wasn't there a couple of weeks ago. That is, in fact, pretty damn sudden.

      • It is unclear from the reporting if the fissure was present for some time but has only recently broken through to the surface. As a caver, I spend an appreciable part of my spare time in underground voids which have been forming for thousands of years (one study I've been involved with hints at a multi-million year history for a UK cave), and are slowly ascending by roof stoping. Eventually they'll break through to the surface, seemingly suddenly but really the result of a millennia-long process.

  • This is news? (Score:4, Informative)

    by charlie merritt ( 4684639 ) on Monday April 02, 2018 @01:16PM (#56367833)
    Seems I've heard of the East African Rift Valley for, like, decades. Only 'news' here is rain washed sediment away and people could see a fault. The entire rift is a fault zone.

    • Re:This is news? (Score:5, Informative)

      by 93 Escort Wagon ( 326346 ) on Monday April 02, 2018 @01:30PM (#56367917)

      The first link in the submission leads to a March 26th photo showing a rather dramatic crack that’s opened up across some fields and a highway.

      I think the story is a reminder that the rift is geologically active - the rift itself has existed for millions of years.

    • Hotspot in the mantle, according to "Rise of the Continents". Pretty good, it was on BBC a while back.

      Nova probably has something similar but with more pictures and fewer long words.

      • "Nova might has something close but with more pictures and less big words."

        .

        FTFY.

      • At Afar, certainly something closely resembling a mantle plume. Further south in the Rift system ... a much trickier proposition. Is there a second plume under the Turkana region where Eastern and Western Rifts separate? Why the tectonic and sedimentary contrasts between Eastern and Western Rifts?

        I attended a 3-day conference largely devoted to such questions a bit over a year ago. No one knows "the" answer, if indeed there is a posable question. Very interesting ; very hard to condense into notes.

    • Re: (Score:2)

      by jd ( 1658 )

      There's a difference between knowing in the abstract sense and KNOWING in the sense that there's a bloody great big rip in the fabric of the continent that is now highly visible. (Admittedly, if it was a rift in the fabric of spacetime and Jack Harkness and The Doctor were involved, it would be more interesting. For the few seconds before a Dalek fleet vaporized you. Nonetheless, interesting.)

    • I was going to say, it looks more like erosion, or subsurface erosion and collapse, rather than some cataclysmic rift to the bowels of the earth.

      As you say, probably more likely a natural process when a rift creates an opportunity for water to wash away sediment.

      Less exciting I suppose.

  • My childhood dream of the earth opening up and swallowing bullies is actually possible!

    • Re: (Score:2)

      by Nkwe ( 604125 )

      My childhood dream of the earth opening up and swallowing bullies is actually possible!

      It is possible, you just have to get the bullies to stand still for a long time.

      • ... or persuade them to jump up and down on a carefully chosen (by you) spot.

        Ground-penetrating radar is your friend.

  • It's just Gaia getting ready to fart.

  • No. Way. (Score:3)

    by DrXym ( 126579 ) on Monday April 02, 2018 @02:06PM (#56368211)
    There was I thinking that Rift Valley was just a figurative name.

    • A more accessible place where you can see the same process happening is Thingvellir in Iceland, which is on the Mid-Atlantic Ridge. It happens to also be the location of the ancient parliament of the country, but researchers are unable to determine exactly where the original thousand-year-old meeting place ("Law Rock") was because of the continual movement of the rift valley.

    • Re: (Score:1)

      by Tablizer ( 95088 )

      There was I thinking that Rift Valley was just a figurative name.

      After it tears, it's "Raft Valley" for those caught in the middle.

    • Ummm, why would you start to think that?

      Without even trying particularly hard, I can get the use of "the Rift Valley" (in various permutations) back to 1894 as a geological term. I don't know enough of East African history to really be interested in following it back into the murkiness of Dr Livingstone's expeditions (though I've scuba dived where he last set off into "the interior") to investigate the naming further, but Livingstone wasn't a geological innocent, and neither were Speke and Burton. I suspe

      • Re: (Score:2)

        by DrXym ( 126579 )
        That's the joke. I don't think it is a figurative name or a metaphor. In the context of the article it is me wondering why it's news that a rift valley is actually called that because it is an actual geological rift formation.
  • Although pretty much anyone who's read much about the Rift Valley knows that Africa is splitting there.
  • DOE SecretaryPruitt said science has nothing to do with the rift, claims plate tectonics is unproven science

  • https://en.wikipedia.org/wiki/... [wikipedia.org]
    https://africa-arabia-plate.we... [weebly.com]
    [Zec 14:4 KJV] 4 And his feet shall stand in that day upon the mount of Olives, which [is] before Jerusalem on the east, and the mount of Olives shall cleave in the midst thereof toward the east and toward the west, [and there shall be] a very great valley; and half of the mountain shall remove toward the north, and half of it toward the south.
    https://discussions.godandscie... [godandscience.org]
    https://www.tomorrowsworld.org... [tomorrowsworld.org]
    https://www.blueletterbible.or... [blueletterbible.org]
    h [biblesearchers.com]

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