Good afternoon everyone, Surgid here, and this afternoon I'm going to rediscuss the first topic that we tackled this morning. So what you see on this screen is an image of the solar system. At the center of the solar system is the star called the Sun, and revolving around the Sun are the eight planets from Mercury down to Neptune. So obviously, as human beings, We only reside at the only habitable planet as of the moment, which is planet Earth. So planet Earth has three layers.
Gaseous layer, called the atmosphere. Liquid layer, called the hydrosphere. And the solid layer, called the lithosphere. So for our lesson for today, we will only focus on the solid layer of the planet Earth, called the lithosphere.
Based on the background image, there are a total of four layers of the Earth's lithosphere. So let's discuss them one by one. Here is the cross-sectional image. So at the top most, we have the crust. Below the crust, the one marked with orange is the mantle.
And then below the mantle is the core. So core is divided into two parts. The first one is outer core. and the bottom most layer is the inner core.
So now that we labeled the layers of the earth's lithosphere, it's time to identify their characteristics and or properties. So naturally, we human beings and other living organisms can only survive at the crust. Okay, so therefore, the characteristic that is attributed to crust is it is the only habitable layer.
So why? It's because most of the natural resources and basic necessities can be found on the crust. Basic necessities such as food, water, air, shelter, etc., etc., even the materialistic things, and natural resources such as water forms and landforms.
forms. Mantel, on the other hand, as you can see in the diagram, is represented by a deep color orange. That's because it's the magma reservoir.
And now you're left with outer core and inner core. Both are considered ball of metals but only one of them is liquid and the other one is solid. So for the outer core, it is the liquid ball of metals, the source of the magnetic field.
While on the other hand, And inner core is the solid ball of metals and is considered the center of gravity. So remember, when we throw things up in the air, all of them have the natural tendency to go down or to fall because of the force called gravity. But the reason why those objects do not immediately fall towards the inner core is because it's barricaded by the three layers above it. We have the crust, mantle, and the outer core.
to barricade falling objects from the inner core. But as you know, all objects are attracted to the inner core due to gravity. Okay now, a lot of people are confused between magma and lava.
There are some, they're technically the same, both of them involve molten rocks. So basically when rocks melt they turn to magma and lava. The difference lies in their position or direction.
So when you say magma, it refers to molten rocks inside a volcano. So remember, mantle is the magma reservoir. So magma is found inside the mantle or below the crust or inside a volcano. On the other hand, once the volcano erupts, it's not magma anymore.
It's called lava. That's the erupted magma. Now, let's arrange the layers of the Earth's lithosphere according to the following parameters.
Let's start with depth. From shallowest or topmost to deepest to the bottommost. So, because crust is at the topmost, therefore, we start our arrangement with crust. And the layer below it is mantle.
And the layer below the mantle is outer core. And the layer below it is the inner core. So that makes crust the shallowest layer and inner core the deepest layer in terms of depth or height. Next, how about thickness? When we say thick, when we arrange the layers in terms of thickness, we arrange it from thinnest to thickest.
So judging by their edges, so crust happens to be the thinnest. followed by the inner core and then outer core and the thickest is Mandel. Now when it comes to the third parameter which is density, we arrange them from lightest to heaviest.
So remember lighter objects tend to float and when they float they remain on top while heavy objects tend to sink and when they sink they got the bottom. So because cross is the topmost layer that means it is the lightest and below it is the mantle and below mantle is the outer core so that makes inner core the heaviest of the four layers. So density trends follow the depth trends as well. They have the same same trajectory basically.
Now for temperature, we arrange it from hottest to coldest. So let's be guided by this simulation from PET. Let me just share my screen.
Okay, let me just manipulate the settings and then zoom this out. Alright, even if we don't have the exact temperature values and ranges from cross down to inner core, we can use the thermometer from the toolbox here. So as you can see, the temperature somewhere near the cross is pretty low.
While as we descend and sink deeper, the number of thermometer increases until inner core. So that makes the topmost layer the coldest layer and the bottommost layer the hottest layer. So let's go back to my PowerPoint presentation.
So temperature, coldest is crust and then followed by mantle, then outer core and inner core happens to be the hottest. So you might be wondering why is crust the coldest out of the core? That's because as you can see, both core and inner core are solid ball of metals.
This is where radioactive decay happens. And as you know, metals are the best conductors of... thermal conductors or conductors of heat.
Compared to crust, wherein we contain not only metals but also non-metals and metalloids as well. And the source of our heat is sun, which takes eight minutes to reach the planet Earth. Compared to outer core and inner core, wherein the radioactive decay is concentrated within it. That's why inner core is the hottest and crust is the coldest. Now, let's review and recap by identifying the layer of the Earth's lithosphere.
Number one, the hottest layer is the inner core. The lightest layer is the crust. The coldest layer is also the crust. The thickest layer is the mantle. The thinnest layer and the topmost layer is the crust.
The heaviest layer happens to be inner core. the only liquid layer happens to be outer core. So you might be wondering why is outer core the only liquid layer out of the four layers of the lithosphere?
It's because the outer core is already surrounded by two solid materials such as the mantle and the inner core. So as the tendency when you are surrounded with too much heat you become to melt that's why outer core is the only liquid layer. It's incomparable to that of the mantle so as if you can see mantle is situated between the crust and the outer core but because mantle is still thick enough compared to the crust which is very thin, No matter and press or mean solid. Now bottom most layer happens to be inner core.
Magma is located inside the mantle and the only habitable layer is the frost. You will die or we will die, all the living organisms will die in the mantle and the core due to the extreme. We will burn first then eventually die if we happen to travel in it. Now Let's move on to the cross by revisiting the seven continents.
So let's start with the biggest continent, which is marked here by color orange. That's Asia, followed by the yellow continent here, which is Africa. And then the light green continent, which is North America. And then below North America is the fourth.
largest continent in dark green that's South America and then to be followed by the mostly icy continent which is Antarctica the one in blue next is Europe the one in red and the smallest continent which also happens to be a hundred is Australia so planet earth is mostly uh 25 percent land and surrounding the continents is the oceans which is basically amalgamation of several sources of water. So we have five major oceans so the largest happens to be the Pacific Ocean which is at the right of Asia and the left of both North and South Americas and then the second largest is Atlantic this is where titanic sand and then third is the indian ocean now for the fourth and fifth which is which are antarctic and arctic one of them is found at the south pole one of them is one of the old so antarctic ocean is found near the south pole and the smallest ocean arctic is found at the north forward. So the reason why we revisited the seven continents and five major oceans is because we have two types of crust supporting them. So supporting the continents is the continental crust and supporting the oceans is the oceanic crust.
So once again, from the name itself, continental crust, it mostly supports continents, while oceanic crust mainly supports oceans. So as you can see, both continental crust and oceanic crust, they are not on the same level with each other. And that is because primarily to the different rock compositions.
So continental crust is mostly made out of granite, while oceanic crust is mostly made out of basalt. Now, as you can see as well, continental crust is bigger and thicker. as well as lighter compared to oceanic crust. It appears to be somewhat elevated while oceanic crust which is found at the below the sea level is thinner and heavier compared to the continental crust. So just remember the four underlined words associated with each type of crust.
For continental supports continents mostly made of granite and thicker and lighter while shiny crust supports oceans is mostly made of basalt and thinner and heavier now before we end our recap let's review first so the lighter crust and uh the thicker crust happen to be continental crust the thinner and heavier crust happens to be oceanic crust. The one that supports the ocean is oceanic crust. The one that supports the continent is the continental crust. The one mostly made of basalt is oceanic crust. And last but definitely not the least, the one mostly made of granite is continental crust.
And that's it for our discussion for today. I hope you learned a lot from the four layers of the Earth's lithosphere and the differences between the continental and oceanic cross. Be ready for our very first performance task tomorrow. As I always say, let's call it a day.
Enjoy the rest of your day. Goodbye.