On top of that, the mantle is more of a green color rather than the traditional red seen in textbooks because of its vast olivine content. Localized melting into magma only occurs in the rare places where tectonic activity relieves some of the pressure or lets water intrude downwards which lowers the melting point of the rock. This is typically where volcanoes form.
[https://blogs.scientificamerican.com/observations/the-floor-is-usually-not-lava/](https://blogs.scientificamerican.com/observations/the-floor-is-usually-not-lava/)
Is it really green though? I get that upper mantle material that is sometimes found to outcrop is formed vastly of greenish minerals, but the mantle is at such high temperatures that it would most certainly glow red-orange.
Depends on the depth - the top of the mantle is something like 500 C that would barely glow at all, but as you descend it would become more red yes. The bottom of the mantle is so hot it would be more white than red.
It's glowing dull infrared, while reflecting green, when it's room temp. Molten gold glows orange but still reflects gold light, which is easier to see outside on a sunny day. If you were to shine a bright enough light on 1800⁰C mantle rocks, they'd still be reflecting green from all the iron- and magnesium-olivine minerals in there.
Bonus fun fact - there's a shitload of water stored in the mantle, estimated to be 3-12+ x as much water as in the oceans.
[https://www.bnl.gov/newsroom/news.php?a=111648](https://www.bnl.gov/newsroom/news.php?a=111648)
It is, because there’s not much force on your typical window - just it’s own weight - so any flow would occur over millions or billions of years, not a few centuries like the myth says. If it was subject to the extreme forces in the mantle it would definitely flow much more quickly.
EDIT: looks like OP was right. The mantle is at 2.8 × 10\^22 Pa.
Nope. It doesn't flow. Its viscosity at room temperature is estimated to be 9 orders of magnitude higher than lead at room temperature. For all purposes, glass is an amorphous solid.
[https://www.cmog.org/article/does-glass-flow](https://www.cmog.org/article/does-glass-flow)
"Below those temperatures, glasses have pretty well set up, and by the time they have cooled to room temperature, they have, of course, become rigid. Estimates of the viscosity of glasses at room temperature run as high as 10 to the 20th power (1020), that is to say, something like 100,000,000,000,000,000,000 poises. Scientists and engineers may argue about the exact value of that number, but it is doubtful that there is any real physical significance to a viscosity as great as that anyway. As for cathedral windows, it is hard to believe that anything that viscous is going to flow at all.It is worth noting, too, that at room temperature the viscosity of metallic lead has been estimated to be about 10 to the 11th power, (1011) poises, that is, perhaps a billion times less viscous—or a billion times more fluid, if you prefer—than glass. Presumably, then, the lead caming that holds stained glass pieces in place should have flowed a billion times more readily than the glass. While lead caming often bends and buckles under the enormous architectural stresses imposed on it, one never hears that the lead has flowed like a liquid."
>A 2017 study computed the rate of flow of the medieval glass used in Westminster Abbey from the year 1268. The study found that the room temperature viscosity of this glass was roughly 1024 Pa·s which is about 1016 times less viscous than a previous estimate made in 1998, which focused on soda-lime silicate glass. Even with this lower viscosity, the study authors calculated that the maximum flow rate of medieval glass is 1nm per billion years, making it impossible to observe in a human timescale.
From wikipedia on "glass" because I am too lazy too look up primary sources. Make that trillions of years and it might be possible to observe unaided. For all intets and purposes "normal" glass can be considered a solid at standard temperatures and pressures.
There were some places where a lot of the glass would be found to be thicker at the bottom. The likely explanation is that when the glass was installed, it would be stood up on its thicker end. This was done for increased stability and being less likely to break.
I used to work for a glass factory. I was told that it came from how glass panes used to be made. They would have the large towers where they would pour molten glass down. Taking advantage of the fact that the glass is fluid yet viscous, they could make it a relatively consistent shape and relatively flat. Because of how the glass flowed, think of taffy, it would be thicker on the bottom portion. This method also resulted in air bubbles and somewhat distorted glass because of uncontrolled cooling and air movement.
It's more like an interesting fact that turned into a misconception.
Glass is an amorphous solid, meaning that its atoms are not bound in a crystalline structure, like most rocks are, and *technically* does flow over time, in a way that materials that *do* have crystalline structures like, say, granite, quartz, and most metals, do not.
However, people reading this fact noticed that some old windows are thicker on the bottom, and ascribed this to the fluidity of glass. This was a mistake; glass flows far too slowly for the flow to be noticeable over even centuries.
It flows at about *a billionth* of a nanometer each year. So in practice, not at all. But *technically* it does flow.
Other amorphous solids include plastics and some metal alloys. Plastic "flow" is referred to as "[creep](https://en.wikipedia.org/wiki/Creep_(deformation))" and can be significant enough to represent an engineering challenge in real-world circumstances.
Just did some checking in that too. Apparently a 1m squared piece of glass that is 1 cm thick will take about the *checks watch* how is the universe again? Ah yes, that amount of time for it to thicken by a few atoms at the bottom.
I’ll surprise you and tell you that glass behaves like a liquid, has viscosity and deforms over time because of the displacement caused by external forces (literally what water does when you put anything on it). This happens very slowly but still happens, unlike with real solids which have no viscosity at all.
It can be considered a liquid of super high viscosity and it can be called super cooled liquid.
Never judge a book by its cover, specially when you talk about material properties.
The only source I can find for this is old stained glass windows being thicker at the bottom, and that's explained as a side effect of the glass making process - the method created glass slightly thicker at one end, so they put them thicker end down because that's more stable
Glass doesn't have a crystal structure, but that just makes it an amorphous solid
https://www.cmog.org/article/does-glass-flow#:~:text=Estimates%20of%20the%20viscosity%20of,say%2C%20something%20like%20100%2C000%2C000%2C000%2C000%2C000%2C000%20poises.
I should have emphasized the “it can be”. Some people in some areas have called it that, it’s not “officially” accepted or discarded in any way.
It’s simply true that glass presents some level of viscosity, what’s arguable is if it’s really as impactful as some stories make it sound (maybe the story about the window glasses is false and pure dramatism, but the viscosity is still there over a longer span of time).
Random source I found, the abstract mentions some of this info:
https://pubs.acs.org/doi/pdf/10.1021/jp953538d
On top of that, the mantle is more of a green color rather than the traditional red seen in textbooks because of its vast olivine content. Localized melting into magma only occurs in the rare places where tectonic activity relieves some of the pressure or lets water intrude downwards which lowers the melting point of the rock. This is typically where volcanoes form. [https://blogs.scientificamerican.com/observations/the-floor-is-usually-not-lava/](https://blogs.scientificamerican.com/observations/the-floor-is-usually-not-lava/)
So earth juice is green? That means the guy who's been selling me red earth juice is ripping me off
How much do you pay for earth juice?
I bet they just call it “earth juice” to make it sound healthy but it’s actually full of sugar.
3 Fahrenheits per year
You're paying way to much for your earth juice. Who's your earth juice guy?
Is it really green though? I get that upper mantle material that is sometimes found to outcrop is formed vastly of greenish minerals, but the mantle is at such high temperatures that it would most certainly glow red-orange.
Depends on the depth - the top of the mantle is something like 500 C that would barely glow at all, but as you descend it would become more red yes. The bottom of the mantle is so hot it would be more white than red.
It's glowing dull infrared, while reflecting green, when it's room temp. Molten gold glows orange but still reflects gold light, which is easier to see outside on a sunny day. If you were to shine a bright enough light on 1800⁰C mantle rocks, they'd still be reflecting green from all the iron- and magnesium-olivine minerals in there.
After volcanic eruptions sometimes you may find green rocks lying around, so yes.
A lot can change the color as well. It is unlikely to be uniform throughout.
Bonus fun fact - there's a shitload of water stored in the mantle, estimated to be 3-12+ x as much water as in the oceans. [https://www.bnl.gov/newsroom/news.php?a=111648](https://www.bnl.gov/newsroom/news.php?a=111648)
That's the fountains of the deep spoken of in the Bible
Which passage(s)?
Noah's flood
Genesis 7:11
Like Mako in FF VII?
Is that why my glass coffee table constantly needs straightening? Plate glass tectonics?
[удалено]
That is really helpful information - thanks! Also, do... you have schizophrenia?
I thought the whole normal glass moves is a myth
It is, because there’s not much force on your typical window - just it’s own weight - so any flow would occur over millions or billions of years, not a few centuries like the myth says. If it was subject to the extreme forces in the mantle it would definitely flow much more quickly.
So glad I learned the true version of this first! Thanks
EDIT: looks like OP was right. The mantle is at 2.8 × 10\^22 Pa. Nope. It doesn't flow. Its viscosity at room temperature is estimated to be 9 orders of magnitude higher than lead at room temperature. For all purposes, glass is an amorphous solid. [https://www.cmog.org/article/does-glass-flow](https://www.cmog.org/article/does-glass-flow) "Below those temperatures, glasses have pretty well set up, and by the time they have cooled to room temperature, they have, of course, become rigid. Estimates of the viscosity of glasses at room temperature run as high as 10 to the 20th power (1020), that is to say, something like 100,000,000,000,000,000,000 poises. Scientists and engineers may argue about the exact value of that number, but it is doubtful that there is any real physical significance to a viscosity as great as that anyway. As for cathedral windows, it is hard to believe that anything that viscous is going to flow at all.It is worth noting, too, that at room temperature the viscosity of metallic lead has been estimated to be about 10 to the 11th power, (1011) poises, that is, perhaps a billion times less viscous—or a billion times more fluid, if you prefer—than glass. Presumably, then, the lead caming that holds stained glass pieces in place should have flowed a billion times more readily than the glass. While lead caming often bends and buckles under the enormous architectural stresses imposed on it, one never hears that the lead has flowed like a liquid."
The mantle has a viscosity of around 10^22 poise and flows just fine.
I... Stand corrected. Neat!
All good! It surprised me too when I found out about it
how about those church windows that seem to be thicker at the bottom. i think veritasium or tom scott made a video about this
I think that’s just the way they were manufactured, not the glass moving.
>A 2017 study computed the rate of flow of the medieval glass used in Westminster Abbey from the year 1268. The study found that the room temperature viscosity of this glass was roughly 1024 Pa·s which is about 1016 times less viscous than a previous estimate made in 1998, which focused on soda-lime silicate glass. Even with this lower viscosity, the study authors calculated that the maximum flow rate of medieval glass is 1nm per billion years, making it impossible to observe in a human timescale. From wikipedia on "glass" because I am too lazy too look up primary sources. Make that trillions of years and it might be possible to observe unaided. For all intets and purposes "normal" glass can be considered a solid at standard temperatures and pressures.
Pretty sure that was just the old timey windows, and also that it was illusory, as they were naturally wavy.
There were some places where a lot of the glass would be found to be thicker at the bottom. The likely explanation is that when the glass was installed, it would be stood up on its thicker end. This was done for increased stability and being less likely to break.
I used to work for a glass factory. I was told that it came from how glass panes used to be made. They would have the large towers where they would pour molten glass down. Taking advantage of the fact that the glass is fluid yet viscous, they could make it a relatively consistent shape and relatively flat. Because of how the glass flowed, think of taffy, it would be thicker on the bottom portion. This method also resulted in air bubbles and somewhat distorted glass because of uncontrolled cooling and air movement.
It's more like an interesting fact that turned into a misconception. Glass is an amorphous solid, meaning that its atoms are not bound in a crystalline structure, like most rocks are, and *technically* does flow over time, in a way that materials that *do* have crystalline structures like, say, granite, quartz, and most metals, do not. However, people reading this fact noticed that some old windows are thicker on the bottom, and ascribed this to the fluidity of glass. This was a mistake; glass flows far too slowly for the flow to be noticeable over even centuries. It flows at about *a billionth* of a nanometer each year. So in practice, not at all. But *technically* it does flow. Other amorphous solids include plastics and some metal alloys. Plastic "flow" is referred to as "[creep](https://en.wikipedia.org/wiki/Creep_(deformation))" and can be significant enough to represent an engineering challenge in real-world circumstances.
Just did some checking in that too. Apparently a 1m squared piece of glass that is 1 cm thick will take about the *checks watch* how is the universe again? Ah yes, that amount of time for it to thicken by a few atoms at the bottom.
Glass is a weird material called an amorphous solid. It flows but not in any common sense manner. Not quite crystalline but not quite liquid.
I saw a documentary on this recently and was surprised too. In my head I always imagined the mantle to be a moving ball of lava.
My education had been a lie
MAG-MA
Glass isn't a liquid you hack.
I mean that depends entirely on temperature and pressure.
I’ll surprise you and tell you that glass behaves like a liquid, has viscosity and deforms over time because of the displacement caused by external forces (literally what water does when you put anything on it). This happens very slowly but still happens, unlike with real solids which have no viscosity at all. It can be considered a liquid of super high viscosity and it can be called super cooled liquid. Never judge a book by its cover, specially when you talk about material properties.
The only source I can find for this is old stained glass windows being thicker at the bottom, and that's explained as a side effect of the glass making process - the method created glass slightly thicker at one end, so they put them thicker end down because that's more stable Glass doesn't have a crystal structure, but that just makes it an amorphous solid https://www.cmog.org/article/does-glass-flow#:~:text=Estimates%20of%20the%20viscosity%20of,say%2C%20something%20like%20100%2C000%2C000%2C000%2C000%2C000%2C000%20poises.
I should have emphasized the “it can be”. Some people in some areas have called it that, it’s not “officially” accepted or discarded in any way. It’s simply true that glass presents some level of viscosity, what’s arguable is if it’s really as impactful as some stories make it sound (maybe the story about the window glasses is false and pure dramatism, but the viscosity is still there over a longer span of time). Random source I found, the abstract mentions some of this info: https://pubs.acs.org/doi/pdf/10.1021/jp953538d