[HN Gopher] North America Is Dripping from Below, Geoscientists ...
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North America Is Dripping from Below, Geoscientists Discover
Author : jandrewrogers
Score : 134 points
Date : 2025-04-05 20:24 UTC (1 days ago)
(HTM) web link (www.jsg.utexas.edu)
(TXT) w3m dump (www.jsg.utexas.edu)
| jfengel wrote:
| Article is dated April 1 but the actual paper is dated March 23.
|
| Sometimes it can be hard to tell when it's outside of your
| domain.
| compootr wrote:
| or an april fool's joke!
| lunarcave wrote:
| > Researchers have discovered that the underside of the North
| American continent is dripping away in blobs of rock -- and that
| the remnants of a tectonic plate sinking in the Earth's mantle
| may be the reason why.
|
| Really appreciate the first sentence of the article having a
| pithy summary of what the whole thing is all about.
| mmooss wrote:
| Yes, thesis statements are very useful, especially in the
| Internet age when we are overloaded with potentially
| interesting things to read. Unless I already believe you have
| something essential, I generally won't follow you on your
| mystery tour.
|
| Maybe that reduces audience engagement time.
| imchillyb wrote:
| I believe it's a shame that the drippings do not create the basis
| of a mantle-stalagmite. That would be a neat feature to study.
|
| 'Our continent keeps on dripping, dripping, dripping, into the
| mantle...'
|
| Doo-doo dah doo-doo.
|
| ---
|
| Is there currently any type of ground penetrating radar or other
| device which could physically confirm the model's output?
| mnky9800n wrote:
| It is not just model output. The paper uses seismic tomography
| to image it:
|
| https://www.nature.com/articles/s41561-025-01671-x
| eigenform wrote:
| The abstract mentions:
|
| > Here we present a full-waveform seismic tomographic model
|
| So presumably, you would actually _do_ the seismic tomography
| (if they haven 't already). Instead of radar, you use the waves
| from earthquakes!
| ggm wrote:
| Steve Miller song at the speed of continental drift.
| zerealshadowban wrote:
| it usually starts with a stalactite, then a stalagmite; by the
| way is there a mnemonic for the two words in English? something
| like t for tumbling and m for mounting...
| xattt wrote:
| Stalactites hold "tight" to the ceiling.
|
| Courtesy of a 30-year-old Bill Nye episode.
| kazinator wrote:
| I also heard this lame one: stalagmites might hang, but
| they don't.
| danwills wrote:
| The one I've heard is 'just remember ants in pants: the mites
| go up, the tites come down'
| level3 wrote:
| I memorized it as "c" for "ceiling" and "g" for "ground."
| sritchie wrote:
| I always remember it with "g" for ground and "c" for
| ceiling... haha but I do like the mites and tites one too in
| a neighbor comment :)
| dec0dedab0de wrote:
| T from the top
| tejtm wrote:
| hope it holds tight...
| kazinator wrote:
| If I needed a mnemonic today, just remember that drops slowly
| drip from stalactites, like drops in a chemical titration
| procedure.
| thebruce87m wrote:
| Tights go down and mites go up.
| mewse wrote:
| That headline feels like a really clever metaphor for something
| but I can't figure out what.
| spike021 wrote:
| it reminds me of how in San Jose, CA, there are several roads
| that were constructed below the local water table. so
| effectively there's always water bubbling/"dripping from below"
| and causing puddles and erosion.
| MrMcCall wrote:
| Related: it's like the "Everything is fine" meme cartoon
| picture, except the people seeing the scene unfold are
| forbidden from talking about fire.
| jl6 wrote:
| That which is good and right is built on deep foundations which
| are often forgotten or neglected in favor of surface level
| activity.
| robotnikman wrote:
| There's something fascinating about knowing that there's movement
| happening hundreds of miles beneath our feet.
| Workaccount2 wrote:
| Its happening right beneath our feet too! Go dig up the rocks
| in your yard, come back a year later, and you will find it's
| full of rocks again.
| kazinator wrote:
| Maybe Trump can put a tariff on it to slow it down.
| pjio wrote:
| It's bad that America is melting from below under Trump. But
| did you know, that Earth was circling around a never ending
| nuclear fusion explosion under Biden? /s
| tim333 wrote:
| The lower mantle has been treating America very unfairly. I'm
| sure it they can tariff penguins they can tariff the mantle
| too.
| mxuribe wrote:
| Its specifically melting the underneath of North
| america....because, the earth is flat...everyone knows that!
| /s
|
| But, let's not worry, because Trump will build a wall, er,
| heat shield, and no more pesky nuclear fusion-based heat will
| ever penetrate our 1%-er bunkers, er i mean, our atmosphere
| to melt our continent....and if some heat should get in,
| well, then ICE will be there to help save the day! /s
|
| :-D
| hoseyor wrote:
| This makes a lot more sense to me as to the origin of the Great
| Lakes, opposed to the common explanation that the extremely sharp
| and deep lakes were carved by glaciers, which one would expect to
| be very shallow instead
| glitchcrab wrote:
| I think the formation of the Lakes by glaciers was
| substantially different to glacial action we see today. It's
| commonly accepted that the Lakes were formed by the existence
| of the Laurentide ice sheet which was up to _2 miles_ thick in
| places - that's vastly different to the glaciers we see today
| and the effects that they have had.
| HelloMcFly wrote:
| While the idea that they filled up from below may make more
| intuitive sense at face value, the "common explanation" in this
| instance is substantiated in many different ways and doesn't
| seem far fetched when you study it a little further.
| amelius wrote:
| Also figuratively.
| Conasg wrote:
| Phrasing!
| crazygringo wrote:
| Is there any possible justification for using the word "dripping"
| rather a normal word like "sinking"?
|
| To me, dripping requires liquid drops that travel through air or
| a vacuum. _Maybe_ through another liquid if the drops cohere. But
| solids can 't drip, and substances can sink or travel or migrate
| through a solid but they can't _drip_ through it.
|
| Is there some special geological meaning of "dripping"? Or is
| this just bad English?
| jofer wrote:
| It's called "mantle drip" or "lithospheric drip" in the
| technical literature. "Lithospheric mantle delamination" is a
| more descriptive variant. We're fond of fun terms in geology.
| E.g. the "jelly sandwich model" vs the "creme brulee model" for
| lithospheric strength is closely related to what's being
| discussed here. And yes, those are the proper technical terms.
|
| Solids can indeed "drip". The mantle is a solid, but it still
| very much flows. "Fluid" means no shear strength, but fluids
| are not the only things that flow and flowing is separate from
| having a shear strength. Fluids do not behave elastically. If
| you stress them at all, they permanently deform. Elastic
| materials behave like a spring up until a point. When you
| stress them, they deform, but will pop back. The mantle is
| viscoelastic. Strain rate matters in how it deforms. When you
| stress at high strain rates it, it deforms, but pops back (i.e.
| shear waves from earthquakes can pass through). If you maintain
| those stresses at a low strain rate, it will slowly permanently
| deform. That's, by definition, flow.
|
| This is a good analogy for what's being discussed:
| https://en.wikipedia.org/wiki/Pitch_drop_experiment
|
| The reason "mantle drip" is used is to evoke a mental image
| similar to that experiment.
| crazygringo wrote:
| Thank you!
|
| Still seems a little weird to include in an article meant for
| a general audience, but I appreciate that geology uses these
| as technical terms.
|
| Since you know the field, can you explain what the difference
| is between a solid flowing and a solid dripping? Thinking
| about it more, my mental model of dripping requires surface
| tension for drops to even exist. But surface tension doesn't
| exist for solids, right? What defines a solid "drop" as
| opposed to, I don't know, just a layer or pieces?
|
| Or am I overthinking this and it was just chosen as a silly
| fun word to use?
| seadan83 wrote:
| Rock behaves like warm wax on geologic timescales. Kinda
| crazy..
|
| Was hoping to find a source to back up my memory on this,FWIW,
| Google's AI summary states it well:
|
| > On geological timescales (millions to billions of years),
| rocks, even those that seem brittle, can deform plastically, or
| flow like wax, due to the immense pressures and temperatures
| deep within the Earth, allowing for slow, gradual deformation
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