Plate tectonics: Geological features of divergent plate boundaries | Khan Academy
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- Опубликовано: 13 окт 2024
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Plate Tectonics -- Geological Features of Divergent Plate Boundaries. Created by Sal Khan.
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on a further note, i just realized out of all the thousands of dollars I've spent at a university, I've learned the most from you. thank you.
This was SO HELPFUL! Mind blown. I understand it now. Thank you so much!
I've listened to you for years on my math homework, i almost shit my pants when i heard your voice on a geology lesson. i love you. you make cramming the night before with no prior knowledge of the subject possible.
So are you planning on doing a geography series? That'd be awesome!
Great drawing of sourdough bread
you are like the best teacher ever! thank you khan academy!
thanks
sal khan is a G!!!!
this cleared up so much confusion, thank you
The lithosphere is stretched and thinned at mid-ocean ridges. It isn't being pushed up by magma. The more correct explanation of this is that the lithosphere is stretching and thinning, and is it gets thinner the asthenosphere flows up towards the surface to fill the gap left behind by thinning rock. The asthenosphere begins to melt as it decompresses, ie. decompression melting. The bread analogy is completely incorrect.
TLDR: Melting doesn't cause rifting. Rifting causes melting. This video is fundamentally incorrect.
I believe you are wrong. The rift valleys are created when the continent lies over an extremely hot part of the mantle, causing the continental crust to bulge up and stretch and thin. During Mid Ocean ridges, hot asthenosphere is ascending and due to low pressure and water and increase of temperature, it causes magma to go upwards. you are right when you say magma isn't pushing it towards. Rifting does eventually cause melting. However, the stretching and thinning is mostly at rift valley, to clarify.
Hi Sarah. You are incorrect. You are probably confused because you are conflating several ideas. Hot parts of the mantle are called hot spots. Sometimes, hot spots and divergent boundaries coincide, but not always. If you read any textbook (since 1990 or so) that describes the forces acting on the lithosphere, you will discover that the largest force acting on the lithosphere is the slab pull force. This is the force the results from the subduction of cold lithosphere at subduction zones. This force pulls on the lithosphere and causes extension that can result resulting in rifting. About 95% of the all of the forces acting on the lithosphere are the result of slab pull. The scenario you describe is physically impossible! If you don't want to do any math, think about Hawaii! It is a hot spot, but not a rift! These things are disconnected.
Thinning the lithosphere results in upward motion of the asthenosphere, bringing higher temperature material (it is hotter because it used to be deeper) closer to the surface. This results in melting, and the initial uplift you describe that precedes rifting.
Also, you need to be specific with terminology when you discuss plate tectonics. We are discussing the lithosphere and asthenosphere when we discuss plate tectonics, not the crust and mantle. It is these sorts of mistakes (like the many errors in this video) the results in student confusion.
Hello, could you go over some of the errors as I'm slightly confused. One major question is how can an incipient sea (e.g. the red sea) form if the hot spot is causing the plate to uplift? Also, what comes first, the updoming/rifting or the melting of the mantle.
Ayo why does the illustration look like Golden Experience Requiem
actually the asthenosphere isn't less dense instead the listhosphere is less dense due to its composition which is felsic and that's why it is floating on the underlying
asthenosphere.
simply, ==> Asthenosphere= less strong (viscous) and denser
==> Lithosphere = strong and less dense
NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO!
No! No! No!
I just finished my tectonic course literally 2 months ago...
(bangs head on desk repeatedly).
Is the pacific plate and the North American plate convergent? Or divergent?
Incognitø • transform
does that mean that there's a hotspot underneath the mid Atlantic ridge? what about the whole seafloor spreading thing then?
do some vids on igneous and metamorphic petrology
@Madpolis7 the plate tectonics model is loaded with problems, and can be traced back to dr. alfred wagerer in 1912 - it has remained largely unchanged for almost a century. modern scientists have demonstrated clear cases showing the earth has been expanding from within since at least 220 million years ago.
i guess i should have specifically asked the uploader for an answer, because i wanted a response from someone who knew more thoroughly what they were talking about. thanks anyway.
What if the earth has magnetic lines that get twisted like the sun and when they break it propels magma into the lithosphere?
Man's comparing the Earth with Pizza Dough
💀
Volcanoes!
The mantle isn't a liquid.
yes but it's viscous
It is molten rocks, in a semi-liquid state
@thejustineaster Lol, hon the expanding earth theory is insane. It would require matter to made from nothing. I'm not talking about quantum level stuff either. This is different.
@savageecho
I am thinking @hedonism13 is just expressing frustration that this video wasn't available when he/she studied it - not that it is inaccurate.
@hedonism13 Look, part of education is correction. You cannot just scream NO! and they walk away and expect people to get it right. Maybe you don't expect people to fix themselves, but if you have a correction please don't sit on it. State your correction, so that he may fix it and the rest of us who did not take tectonic courses will not be mislead. That being said, would you care to help out?
isn't the expanding earth theory turning out to be more sound than the plate tectonic theory?
@Madpolis7 not true. plasma discharge can be responsible for the creation of matter, so given the earth's atmosphere has plasma discharges, this would produce the materials needed. even more likely, when the earth exchanges energy with magnetic and electric fields radiating from, among other things, the sun, then we would expect to have lots of dust, water and minerals created. obviously it's not insane. in fact, numerous reconstructions suggest a 99% matching of all the continental boundaries.
@wombiroller Yeah, with his/her "wut" response I figured that either he/she didn't understand what I was driving at or was, as you put it, frustrated. I was only responding because if there was something wrong I wanted to know since my science is pretty weak, which is sad because I still seam to be better than most Americans.
why does this guy sound like the guy from Mr. Raymonds civics class
are you Aiden Croffhard for HJC
truth is stranger than fiction
So we are all here for earth science homework?
@McDohnuts Earth isn't growing bigger with time! Plates may be pushed apart at divergent boundaries and that creates new crust, but plates also come together and get destroyed at convergent boundaries. Watch the next video in the series, "Plate Tectonics - Geological features of Convergent Plate Boundaries." ;)
Interesting.
Looks like the earth growing bigger in time...
@MrNewkingjames Couldn't help taking a look at your channel with your comment and the username you have. Do you still believe in noahs arc?
lol the Earth is a sourdough bread
i'm getting hungry...
you can never see his cursor its so annoying
LOL!
@savageecho
wut
ho cares !!!!!!!!!!!!!!!!!!!!!!!
U stutter too much
@hedonism13 explain?