Mantle Convection and Plate Tectonics

Good evening everyone, I am Sir Jude and today here's the video lecture for our lesson this morning. So let's pick up from where we left off yesterday by analyzing the picture and answering the questions that followed. Let's start with number one. What material is present in letter A? So obviously, what you see in the picture is anatomy of the mantle and you know that the contents of the mantle is not under the ALMA. Number two, in what direction does A1 rotate? So A1 rotates in a counterclockwise position. Number three, in what direction does A2 rotate? A2 rotates in a clockwise position. Number four, what process is depicted in the illustration above? So since most of the picture depicts the mantle, and we assume that below the mantle is the core, and since core is the heat source, we see that the middle, we have warm magma rising, and then at the sides, we have cold magma sinking. So the process depicted above is convection currents, which was our lesson yesterday. Number five, where do convection currents occur? Convection currents occur, as already aforementioned multiple times, inside the mantle. Number six, where is the heat source of convection currents? The heat source of convection currents is the layer below it and that's not other than four okay so now that we've recap convection currents it's time to watch the video for our next lesson Okay, so what you've seen in the video is that, especially in this region, you see the convection currents. So at the left, you have the counterclockwise rotation, and on the right, you have the clockwise rotation. And there are two sets of consequences. So you have here, you have one oceanic cross moving to the left, and another oceanic cross moving to the right. So that's oceanic-oceanic divergence. And the other consequence is depicted by this. scenario wherein one crust subducts under the other crust. So this is a convergent boundary with subduction. So those specific plate boundaries that we mentioned, oceanic-oceanic divergence and continental oceanic divergence, these are otherwise known as ridge push and slab push. There were a pair of scientists who conceptualized and had an interest on sea flower spreading. And they were credited as, or they were studied by Harry Hammond Hess and Robert Taits. So because of them, we're studying sea flower spreading. That is one of the major, let's say, important and significant studies when it comes to geology under earth science. So approximately, the earth, or rather the seafloor, spreads at 3 centimeters per year. So 3 centimeters out of 365 days, that's too short or too slow. And that's good because that allows for a lesser impact of earthquakes. Because if it is more than 3 centimeters per year, then we're probably rolling up and down every year. Okay, so let's start with the first repercussion of convection currents, which is the separation of two oceanic thrusts. So, as a separation, one oceanic thrust moves to the left and the other one moves to the right, as evidenced by the direction of the arrows here. Alright, so if you see two crusts separating, then the driving stress is none other than tension. The specific plate boundary is oceanic-oceanic divergence. And the geological formation found at the center is the mid-ocean ridge. So all in all, these descriptions are or denote ridge push or seafloor spreading. Now for the other consequence of convection currents, so here we have different set of crusts that are involved. So the first one we have continental crust which is stationary, not moving because there's no arrow designated to it. And beside the continental crust or rather below it, is the oceanic thrust. And because the oceanic thrust collides and subducts under the continental thrust, the driving stress involved is compression. So let's recall, any crust that subducts, usually it's oceanic, is because it's heavier compared to the, or denser compared to the continental thrust. The specific plate boundary is continental oceanic convergence. And when you see a deep geological formation at the subduction zone, that's what you call the trench. So this specific plate boundary is denoted or otherwise known as slab pool or subduction. And basically that's it on our lesson for today. It's time for a recap. Alright, so let's point the arrows where convection currents, bridge push, and slab pull happen. Let's start with convection currents because without convection currents, bridge push and slab pull will never happen. So convection currents are represented by the circular arrows there. One moving in the counterclockwise direction and the other one moving in the clockwise direction because as you recall, warm magma rises and then cold magma sinks. It's a cycle. Now when you say ridge push, you have two oceanic crusts separating from each other and those are represented, that specific plate mount is represented by the two red arrows, one moving to the left and the other one at the top. Slav pool is otherwise known as continental oceanic convergence wherein the oceanic crust subducts under the continental crust. So we never see a crust or an oceanic crust subducting, we call that the slav pool. Okay, so now let's explain how ridge push and slav pool are parallel in the following scenarios. So for those of you who weren't able to grasp this lesson the moment I lectured it, there are some practical applications that do not necessarily involve the continental and oceanic grasp that may parallel or mirror ridge push and slump pull. So for example, let's start with conveyor belts. So any of you has... uh don groceries at the mall knows that when you're about to pay at the cashier you load your item unload your items at the conveyor belt so when you load your items at the conveyor belt and the conveyor belt starts to move them uh move them towards the cashier no that's a rich push and once the platform goes down without your item obviously that's slag pool On the second scenario, you have a chain which is sinking because of an anchor being unloaded down the ship. So when the chain is moving at a straightforward position, that's reach push. And once it descends, because the anchor was unloaded, that's a manifestation of slab pull. And finally, with the escalator scenario, if you are on the platform, whether you're ascending or descending, you're undergoing reach push. And once the platform that you step on finally descends under the floor or under the escalator machine, that's an evidence of slump pull. So this is how reach push... These are how ridge push and slab pull are paralleled in scenarios that do not technically involve continental and oceanic thrusts. Alright, so because we're done with convection currents and ridge push and slab pull, which drive tectonic plates, so what will happen if the core is cold? So because convection currents only occur because the core is cold. hot. What will happen if the core is cold? So obviously there will be a lot of rubber cautions. So there will be no convection currents anymore because the rising of magma and the sinking of magma only happen when the core is hot. If there will be no convection currents, probably there will be no ridge push and slab pull anymore. And if there's no ridge push and slab pull, there will be no plate movement and boundaries as well. The ones that we didn't tackle as well will not probably happen anymore because the plates are stationary and not moving. So as a consequence, there will also be no geological formations, no mountains, mountain ranges, hills, volcanoes, islands, trenches, reef valleys, mid-ocean regions and other landforms and water forms. There's probably a high possibility of known that existence of natural disasters because once again the cross is not moving anymore and probably the continents will remain intact together so we'll probably have a super continent where all the continents are uh situated next to each other and not separated by oceans so it is possible to still live under the circumstances but the earth will be geologically dead So that's it. Basically, if the core is cold, then the entire first quarter of science in grade 10 will be erased because we only discuss these topics only because the core is hot. Alright, so tomorrow we will have our performance task involving sea floor spreading. I already uploaded an edited video myself on how to assemble the improvised seafloor spreading using the show box and these seafloor stripe printouts. Okay? But to wrap things up, to conclude this lesson, let's answer this question. If the seafloor spreads out, remember, at three centimeters per year, approximately, how come the earth never expands and instead maintains its size? When I translate it to Tagalog, kung naghiwalay ang oceanic crust, how come hindi naman nalaki ang planet Earth at hanggang ngayon, namaintain pa rin yung kanyang size? Never siyang lumaki, never rin siyang lumigil. The answer lies because of slab pool. So what is it with slab pool that allows the Earth to maintain its size despite the presence of sea floor spreading? So let's complete the sentence below with the six blanks. So the subducted cross, blank to the blank, melts to blank, is expelled by blank. As blank goes to blank, then the cycle repeats. So the subducted cross will sink to the mantel. And because there's convection currents in the mantel making it hot, the subducted cross will met to magma. Once there's enough build up of pressure magma will be expelled by volcanoes. And as you know once magma is expelled by volcanoes it's now called as lava. And once lava cools down at a certain amount of time it will be cold to rocks. Then the cycle repeats again. So let me reread the sentence for you. Why is it that the earth never expands, maintains its size, despite the presence of sea floor spreading? So the subducted crust sinks to the mantle. Sorry for the apologies for the missed spelling. The subducted crust sinks to the mantle, melts to magma. is expelled by volcanoes as lava pulls the rocks, then the cycle repeats. So Earth has a way of geologically recycling its own natural resources. Isn't it great how Earth does not need any human or living accompaniment just to recycle its own natural resources? Alright, and there you go, that's where you push and it's love for you. Tomorrow, if we have classes, if there are no suspension classes, we will finally be able to assemble your improvised, see your spreading. See you tomorrow. Stay safe and dry. Goodbye.

Number two, in what direction does A1 rotate? So A1 rotates in a counterclockwise position. Number three, in what direction does A2 rotate? A2 rotates in a clockwise position. Number four, what process is depicted in the illustration above?

So since most of the picture depicts the mantle, and we assume that below the mantle is the core, and since core is the heat source, we see that the middle, we have warm magma rising, and then at the sides, we have cold magma sinking. So the process depicted above is convection currents, which was our lesson yesterday. Number five, where do convection currents occur?

Convection currents occur, as already aforementioned multiple times, inside the mantle. Number six, where is the heat source of convection currents? The heat source of convection currents is the layer below it and that's not other than four okay so now that we've recap convection currents it's time to watch the video for our next lesson Okay, so what you've seen in the video is that, especially in this region, you see the convection currents. So at the left, you have the counterclockwise rotation, and on the right, you have the clockwise rotation. And there are two sets of consequences.

So you have here, you have one oceanic cross moving to the left, and another oceanic cross moving to the right. So that's oceanic-oceanic divergence. And the other consequence is depicted by this.

scenario wherein one crust subducts under the other crust. So this is a convergent boundary with subduction. So those specific plate boundaries that we mentioned, oceanic-oceanic divergence and continental oceanic divergence, these are otherwise known as ridge push and slab push. There were a pair of scientists who conceptualized and had an interest on sea flower spreading.

And they were credited as, or they were studied by Harry Hammond Hess and Robert Taits. So because of them, we're studying sea flower spreading. That is one of the major, let's say, important and significant studies when it comes to geology under earth science.

So approximately, the earth, or rather the seafloor, spreads at 3 centimeters per year. So 3 centimeters out of 365 days, that's too short or too slow. And that's good because that allows for a lesser impact of earthquakes.

Because if it is more than 3 centimeters per year, then we're probably rolling up and down every year. Okay, so let's start with the first repercussion of convection currents, which is the separation of two oceanic thrusts. So, as a separation, one oceanic thrust moves to the left and the other one moves to the right, as evidenced by the direction of the arrows here. Alright, so if you see two crusts separating, then the driving stress is none other than tension.

The specific plate boundary is oceanic-oceanic divergence. And the geological formation found at the center is the mid-ocean ridge. So all in all, these descriptions are or denote ridge push or seafloor spreading.

Now for the other consequence of convection currents, so here we have different set of crusts that are involved. So the first one we have continental crust which is stationary, not moving because there's no arrow designated to it. And beside the continental crust or rather below it, is the oceanic thrust.

And because the oceanic thrust collides and subducts under the continental thrust, the driving stress involved is compression. So let's recall, any crust that subducts, usually it's oceanic, is because it's heavier compared to the, or denser compared to the continental thrust. The specific plate boundary is continental oceanic convergence. And when you see a deep geological formation at the subduction zone, that's what you call the trench.

So this specific plate boundary is denoted or otherwise known as slab pool or subduction. And basically that's it on our lesson for today. It's time for a recap.

Alright, so let's point the arrows where convection currents, bridge push, and slab pull happen. Let's start with convection currents because without convection currents, bridge push and slab pull will never happen. So convection currents are represented by the circular arrows there.

One moving in the counterclockwise direction and the other one moving in the clockwise direction because as you recall, warm magma rises and then cold magma sinks. It's a cycle. Now when you say ridge push, you have two oceanic crusts separating from each other and those are represented, that specific plate mount is represented by the two red arrows, one moving to the left and the other one at the top. Slav pool is otherwise known as continental oceanic convergence wherein the oceanic crust subducts under the continental crust. So we never see a crust or an oceanic crust subducting, we call that the slav pool.

Okay, so now let's explain how ridge push and slav pool are parallel in the following scenarios. So for those of you who weren't able to grasp this lesson the moment I lectured it, there are some practical applications that do not necessarily involve the continental and oceanic grasp that may parallel or mirror ridge push and slump pull. So for example, let's start with conveyor belts.

So any of you has... uh don groceries at the mall knows that when you're about to pay at the cashier you load your item unload your items at the conveyor belt so when you load your items at the conveyor belt and the conveyor belt starts to move them uh move them towards the cashier no that's a rich push and once the platform goes down without your item obviously that's slag pool On the second scenario, you have a chain which is sinking because of an anchor being unloaded down the ship. So when the chain is moving at a straightforward position, that's reach push. And once it descends, because the anchor was unloaded, that's a manifestation of slab pull. And finally, with the escalator scenario, if you are on the platform, whether you're ascending or descending, you're undergoing reach push.

And once the platform that you step on finally descends under the floor or under the escalator machine, that's an evidence of slump pull. So this is how reach push... These are how ridge push and slab pull are paralleled in scenarios that do not technically involve continental and oceanic thrusts.

Alright, so because we're done with convection currents and ridge push and slab pull, which drive tectonic plates, so what will happen if the core is cold? So because convection currents only occur because the core is cold. hot.

What will happen if the core is cold? So obviously there will be a lot of rubber cautions. So there will be no convection currents anymore because the rising of magma and the sinking of magma only happen when the core is hot. If there will be no convection currents, probably there will be no ridge push and slab pull anymore.

And if there's no ridge push and slab pull, there will be no plate movement and boundaries as well. The ones that we didn't tackle as well will not probably happen anymore because the plates are stationary and not moving. So as a consequence, there will also be no geological formations, no mountains, mountain ranges, hills, volcanoes, islands, trenches, reef valleys, mid-ocean regions and other landforms and water forms. There's probably a high possibility of known that existence of natural disasters because once again the cross is not moving anymore and probably the continents will remain intact together so we'll probably have a super continent where all the continents are uh situated next to each other and not separated by oceans so it is possible to still live under the circumstances but the earth will be geologically dead So that's it. Basically, if the core is cold, then the entire first quarter of science in grade 10 will be erased because we only discuss these topics only because the core is hot.

Alright, so tomorrow we will have our performance task involving sea floor spreading. I already uploaded an edited video myself on how to assemble the improvised seafloor spreading using the show box and these seafloor stripe printouts. Okay? But to wrap things up, to conclude this lesson, let's answer this question.

If the seafloor spreads out, remember, at three centimeters per year, approximately, how come the earth never expands and instead maintains its size? When I translate it to Tagalog, kung naghiwalay ang oceanic crust, how come hindi naman nalaki ang planet Earth at hanggang ngayon, namaintain pa rin yung kanyang size? Never siyang lumaki, never rin siyang lumigil.

The answer lies because of slab pool. So what is it with slab pool that allows the Earth to maintain its size despite the presence of sea floor spreading? So let's complete the sentence below with the six blanks.

So the subducted cross, blank to the blank, melts to blank, is expelled by blank. As blank goes to blank, then the cycle repeats. So the subducted cross will sink to the mantel. And because there's convection currents in the mantel making it hot, the subducted cross will met to magma. Once there's enough build up of pressure magma will be expelled by volcanoes.

And as you know once magma is expelled by volcanoes it's now called as lava. And once lava cools down at a certain amount of time it will be cold to rocks. Then the cycle repeats again. So let me reread the sentence for you. Why is it that the earth never expands, maintains its size, despite the presence of sea floor spreading?

So the subducted crust sinks to the mantle. Sorry for the apologies for the missed spelling. The subducted crust sinks to the mantle, melts to magma. is expelled by volcanoes as lava pulls the rocks, then the cycle repeats.

So Earth has a way of geologically recycling its own natural resources. Isn't it great how Earth does not need any human or living accompaniment just to recycle its own natural resources? Alright, and there you go, that's where you push and it's love for you.

Tomorrow, if we have classes, if there are no suspension classes, we will finally be able to assemble your improvised, see your spreading. See you tomorrow. Stay safe and dry.

Goodbye.

Transcript for:Mantle Convection and Plate Tectonics

Transcript for:
Mantle Convection and Plate Tectonics