INTERNAL STRUCTURE OF THE EARTH | Unit 1 Module 2 - Grade 10 Science Lesson | MELC-Based [TEACH]

Summary

Welcome to CaViTeach, where today's lesson delves into Earth's internal structure, highlighting its five layers: the crust, mantle, outer core, inner core, and atmosphere. The inner core, made of iron and nickel alloy, is incredibly dense and hot at 5000°C, contrasting with the molten outer core at 2000°C. The mantle, composed of silicate rocks and divided into the upper, transition, and lower regions, is solid despite its extreme heat. The crust, Earth's thin outer layer, varies in thickness and composition, with continental crust being less dense than oceanic. This episode wraps up with a teaser for the next, focusing on the atmosphere.

Takeaways

• 🌐 The Earth has five concentric layers: crust, mantle (upper and lower), outer core, inner core, and atmosphere.
• 🔥 The inner core is the hottest part of the Earth with a temperature of about 5000°C, composed of solid iron and nickel alloy.
• 🌀 The outer core, with a temperature of around 2000°C, is made up of molten iron and nickel alloy, contributing to Earth's magnetic field.
• 🌍 The mantle, which makes up 80% of Earth's volume and 68% of its mass, is primarily composed of silicate rocks containing silicon, iron, oxygen, and magnesium.
• 🌡️ The asthenosphere, a layer within the mantle, is a soft and weak layer responsible for the movement of lithospheric plates, leading to earthquakes.
• 🏔️ The crust is the thinnest and outermost layer, divided into oceanic crust (7-10 km thick) and continental crust (35-40 km thick), with different compositions and densities.
• 🌋 The Mohorovicic Discontinuity marks the boundary between the crust and the mantle, while the Gutenberg Discontinuity is the boundary between the outer core and the lower mantle.
• 🧲 The Earth's magnetic field is believed to be generated by the movement of molten iron and nickel in the outer core.
• 🌌 The Lehmann Discontinuity is the boundary between the solid inner core and the molten outer core, discovered by Inge Lehmann.
• 🌬️ The atmosphere, the fifth layer, will be discussed in a future episode, highlighting the structure and composition of Earth's outermost layer.

Q & A

What are the five concentric layers of the Earth?

The five concentric layers of the Earth are the crust, the mantle (divided into upper and lower portions), the outer core, the inner core, and the atmosphere.

What is the diameter of the Earth's inner core?

The inner core has a diameter of approximately 2,600 kilometers.

What are the main constituents of the inner core?

The inner core is primarily composed of an iron and nickel alloy.

What is the approximate temperature of the inner core?

The inner core has an approximate temperature of 5,000 degrees Celsius.

Why is the inner core solid despite its high temperature?

The inner core is solid due to extreme pressure, a phenomenon known as pressure freezing, which counteracts the melting effect of the high temperature.

How do scientists know that the inner and outer core are composed of iron and nickel alloy?

Scientists deduce this composition from the Earth's magnetic field, which is generated by the movement of molten iron and nickel in the outer core, and from the density of the Earth, which is higher than that of crust rocks, suggesting denser materials like iron and nickel in the core.

What is the significance of the Lehmann Discontinuity?

The Lehmann Discontinuity is the boundary between the inner and outer core, named after Inge Lehmann who discovered that the outer core is molten and the inner core is solid.

What is the mantle's composition and its role in the Earth's structure?

The mantle is composed mostly of silicate rocks containing silicon, iron, oxygen, and magnesium. It makes up 80% of Earth's volume and 68% of its mass, serving as an intermediate zone between the crust and the core.

What is the Asthenosphere and its relation to plate tectonics?

The Asthenosphere is a soft, weak, and partially molten layer of the upper mantle that causes the movement of lithospheric plates, leading to continental drift and earthquakes.

What are the two types of crust found on Earth and their main differences?

There are two types of crust: continental crust, which is thicker and composed of less dense rocks like granite, and oceanic crust, which is thinner and made up of denser rocks like basalt.

What is the Mohorovicic Discontinuity and who is it named after?

The Mohorovicic Discontinuity is the boundary between the crust and the mantle, named after the Croatian meteorologist and seismologist Andrija Mohorovicic.

Outlines

00:00

🌐 Exploring Earth's Internal Structure

This paragraph introduces the Caviteñan Virtual Teaching (CaViTeach) and delves into the Earth's internal structure, highlighting its five concentric layers: the crust, mantle, outer core, inner core, and atmosphere. It starts with the innermost layer, the inner core, which is approximately 2,600 kilometers in diameter and composed of iron and nickel alloy. The inner core's temperature is around 5,000 degrees Celsius, which is significantly hotter than the outer core at 2,000 degrees Celsius. The paragraph discusses the composition of both the inner and outer core, explaining that while the inner core is solid due to 'pressure freezing,' the outer core is molten. The discussion also touches on how scientists deduced the composition of the cores, mentioning the Earth's magnetic field and the density of the planet compared to meteorites. The boundaries between the inner and outer core (Lehmann Discontinuity) and the mantle (Gutenberg Discontinuity) are introduced, with a brief mention of the mantle's composition and its division into the upper mantle, transition zone, and lower mantle.

05:04

🌍 Delving into the Mantle and Crust

The second paragraph continues the exploration of Earth's layers, focusing on the mantle and crust. It describes the mantle as the intermediate zone between the crust and the core, composed mainly of silicate rocks rich in silicon, iron, oxygen, and magnesium. The mantle is divided into the upper mantle, transition zone, and lower mantle, with the Asthenosphere, a soft, weak layer made of hot molten materials, playing a crucial role in plate tectonics and earthquake activity. The boundary between the outer core and lower mantle, known as the Gutenberg Discontinuity, is named after Beno Gutenberg. The paragraph then transitions to the crust, detailing its composition and the difference between oceanic and continental crust. It explains that the crust is thinner than the mantle, with the continental crust being less dense and composed of granite, while the oceanic crust is denser and made of basalt. The Mohorovicic Discontinuity, marking the boundary between the crust and mantle, is also introduced. The paragraph concludes with an invitation for questions and a call to action for viewers to engage with the content by liking, sharing, and subscribing to the channel.

Keywords

💡Crust

The crust is the Earth's outermost layer, which is thin and composed of two types: oceanic and continental. In the video, it is mentioned that the continental crust is thicker, ranging from 35 to 40 kilometers, and is primarily made up of elements like sodium, oxygen, silicon, aluminum, potassium, and calcium. It is found under land masses and is less dense, consisting of rocks such as granite. The oceanic crust, on the other hand, is thinner at 7 to 10 kilometers and is denser, composed mainly of basalt and found under the ocean floors. The crust is a critical part of the Earth's structure as it is the layer we live on and interact with directly.

💡Mantle

The mantle is the layer beneath the Earth's crust, making up 80% of the Earth's volume and 68% of its mass. It is primarily composed of solid silicate rocks containing elements like silicon, iron, oxygen, and magnesium. The mantle is divided into the upper mantle, transition zone, and lower mantle, with the upper mantle being 670 kilometers thick and the lower mantle 2230 kilometers thick. The video explains that the mantle's temperature ranges from 1500 to 3000 degrees Celsius, which is much hotter than boiling water. The mantle's composition and temperature are vital for understanding the Earth's internal dynamics, including plate tectonics and volcanic activity.

💡Outer Core

The outer core is a layer between the mantle and the inner core, composed of molten iron and nickel alloy. Despite being cooler than the inner core, with an approximate temperature of 2000 degrees Celsius, it is still extremely hot. The video script highlights that the outer core's molten state is due to the extreme temperatures, which is significant for understanding the Earth's magnetic field. The movement of the molten iron and nickel in the outer core generates the Earth's magnetic field, which is essential for protecting the planet from harmful solar radiation.

💡Inner Core

The inner core is the Earth's innermost layer, with a diameter of 2600 kilometers, and is composed of solid iron and nickel alloy. Despite the extreme temperature of approximately 5000 degrees Celsius, which is 250 percent hotter than the outer core, the inner core remains solid due to the immense pressure, a phenomenon known as pressure freezing. The inner core's composition and state are crucial for understanding the Earth's overall density and the generation of its magnetic field, as discussed in the video.

💡Lehmann Discontinuity

The Lehmann Discontinuity is the boundary between the Earth's outer core and inner core. It is named after Inge Lehmann, a Danish seismologist who discovered the difference in the state of matter between these two layers. The video script explains that the outer core is molten, while the inner core is solid, which is a significant discovery for understanding the Earth's internal structure and the dynamics of its core.

💡Asthenosphere

The asthenosphere is a layer within the upper mantle, described in the video as a soft, weak, and partially molten zone. It is approximately 180 kilometers thick and has temperatures ranging from 300 to 800 degrees Celsius. The asthenosphere plays a crucial role in the movement of tectonic plates, as its semi-molten state allows for the convection currents that drive plate tectonics, leading to geological activities such as earthquakes and the creation of mountains.

💡Gutenberg Discontinuity

The Gutenberg Discontinuity is the boundary between the Earth's outer core and lower mantle. It is named after Beno Gutenberg, an American-German seismologist. The video script mentions this discontinuity as a significant marker in understanding the Earth's internal structure, as it separates the solid mantle from the molten outer core, which is essential for studying the Earth's dynamics and seismic activities.

💡Mohorovicic Discontinuity

The Mohorovicic Discontinuity, often abbreviated as the Moho, is the boundary between the Earth's crust and mantle. It is named after Andrija Mohorovicic, a Croatian meteorologist and seismologist. The video script explains that this discontinuity is a key layer in the Earth's structure, marking the transition from the relatively light and brittle crust to the denser, hotter mantle below.

💡Concentric Layers

The term 'concentric layers' refers to the Earth's internal structure, which is divided into several layers that are concentric, or circular, around the Earth's center. The video script discusses the five main layers: crust, mantle, outer core, inner core, and atmosphere. Understanding these layers is fundamental to the study of geology and the Earth's composition, as each layer has distinct properties and plays a different role in the planet's overall function.

💡Pressure Freezing

Pressure freezing is a phenomenon mentioned in the video script to explain why the Earth's inner core is solid despite its extremely high temperatures. It refers to the process where extreme pressure can counteract the melting effects of high temperatures, causing materials that would normally be molten to remain solid. This concept is crucial for understanding the state of the inner core and its implications for the Earth's magnetic field and overall structure.

Highlights

Introduction to the five concentric layers of the Earth: crust, mantle, outer core, inner core, and atmosphere.

The inner core is approximately 2,600 kilometers in diameter and consists of iron and nickel alloy.

The inner core has an extreme temperature of 5,000 degrees Celsius, which is 250% hotter than the outer core.

The outer core is molten iron and nickel alloy despite being cooler than the inner core, due to pressure freezing.

Earth's magnetic field is generated by the movement of molten iron and nickel in the outer core.

The overall density of the Earth suggests a denser core composition than the crust's rocks.

Meteorite analysis reveals the Earth's core likely contains iron and nickel, similar to Chrondite.

The Lehmann Discontinuity marks the boundary between the solid inner core and the molten outer core.

The mantle is the largest layer of Earth, making up 80% of its volume and 68% of its mass.

The mantle is composed mainly of silicate rocks with a temperature range from 1,500 to 3,000 degrees Celsius.

The asthenosphere, a part of the upper mantle, is responsible for the movement of lithospheric plates and continental drift.

The Gutenberg Discontinuity is the boundary between the outer core and the lower mantle.

The crust is the thinnest and outermost layer, consisting of oceanic and continental types with different compositions and thicknesses.

The Mohorovicic Discontinuity is the boundary between the crust and the mantle.

The crust's composition varies, with continental crust made of less dense rocks like granite and oceanic crust of denser rocks like basalt.

A detailed table of the element composition of the Earth's crust is provided.

A teaser for the next episode, which will discuss the Earth's atmosphere as the fifth concentric layer.

Invitation for students to ask questions and engage with the content through likes and shares.

Transcripts

hello students! Welcome to Caviteñan Virtual Teaching or CaViTeach

for today's episode we will be discussing the internal structure of the Earth

for we all know there are five concentric layers of the earth

the first one is the crust the second one is the mantle which is divided

to upper at lower portions. Third is the outer core. Fourth is the inner core

and the fifth one, can you guess it?

You are right! It is our Atmosphere!

let us discuss these concentric layers one by one starting with the innermost

the inner core has two thousand six hundred kilometers in diameter and

consists of iron and nickel alloy. The inner core of our planet

has an approximate temperature of five thousand degree celsius

this is 250 percent hotter than the next layer which is the outer core

which has an approximate temperature of two thousand degrees celsius

and has a thickness of two thousand two hundred fifty kilometers

if we will look into the approximate temperatures of the innermost layers of our planet,

which one is hotter?

the outer core with two thousand degree celsius or the inner core with five thousand degree celsius?

if you think the inner core is hotter, you are right!

both inner and outer core are composed of Iron and Nickel Alloy

So if inner core is the hottest,

Which of them has molten iron and nickel alloy?

the inner core? or the outer core?

if you answered inner core...

well i cannot blame you

but the correct answer is outer core

the inner core is made up of solid iron and nickel alloy

while the outer core is made up of molten iron and nickel alloy

Why?

the extreme temperature of the inner core could have molten the iron

and Nickel but it is believed to be solidified as a

result of extreme pressure scientifically known as pressure freezing

but, how did our scientists were able to say

that the inner at outer core are made up of iron and nickel alloy? (How did you says so?)

How did you say so?

here are the explanations of the scientists regarding that

First, the earth has magnetic field

and they believe that we have magnetic field because of the movement

of molten iron and nickel in the outer core.

Iron and Nickel are both dense and magnetic in nature

Second, the overall density of the earth is way higher than the density of rocks in the crust

this suggests that the inside must be made up of something denser than rocks

based on the analysis of experts on meteorites

they found out that it contains Chrondite

Chrondite is made up of the elements like Iron

Silicon, Magnesium, Oxygen, and some contains Nickel

the earth and meteorites has almost the same densities

thus the earth's mantle rock and the meteorites minus

its iron have the same densities does it make sense

doesn't make sense

the boudary between inner and outer core is called Lehmann Discontinuity

It is named after Inge Lehmenn who is a Danish Seismologist

who discovered that the the outer core is molten and the inner core is solid

the second concentric layer that we will discuss is the mantle

the mantle is the intermediate zone between the crust and the core and

consists mostly of solid rocks

the mantle makes up the 80 percent of Earth's volume and 68 percent of Earth's mass

it has an approximate thickness of two thousand nine hundred kilometers

with a temperature ranging from fifteen thousand degrees celsius to thirty thousand degree celsius

it is 150 to 300 times as hot as boiling water

the mantle is mainly made up of silicate rocks specifically the elements

silicon, iron, oxygen and magnesium

and contrary to common belief, the mantle is solid since both s waves and p waves can pass through it

the mantle has three parts or regions. The upper mantle, the transition zone, and the lower mantle

the upper mantle has a thickness of 670 kilometers

and the lower mantle has a thickness of 2230 kilometers

In the mantle, we can find the layer called the Asthenosphere

or the low-velocity zone

it is a soft, weak, top layer of the upper mantle that is made up of hot molten materials

it has a thickness of 180 kilometers and has a temperature ranging from 300 degree celsius

to 800 degrees celsius

since the asthenosphere is molten and flowing underneath the crust

it causes the movements of lithospheric plates

which is responsible to the movement of continents

that is why we have earthquakes

the boundary between the outer core and lower mantel is called

Gutenberg Discontinuity named after Beno Gutenberg who is an American-German Seismologist

the boundary between upper mantle and crust, which we will discuss next

is called Mohorovicic Discontinuity

named after Andrija Mohorovicic who is a Croatian Meteorologist and Seismologist

the next concentric layer that we will discuss is the Crust

the crust is the thinnest, outermost, rocky layer of the earth

that is made up of two parts

the oceanic crust and the continental crust

continental crust has a thickness of 35 to 40 kilometers

and is mainly made up of the elements sodium

oxygen, silicon, aluminum, potassium, and calcium

the continental crust is usually found under land masses

and is made up of less dense rocks such as granite

On the other hand, the oceanic crust has a thickness of 7 to 10 kilometers

Oceanic Crust is found under ocean floors and is made up of dense rocks such as basalt.

The crust has two layers, the upper layer which is composed of granite

which is only found in the continental crust

and the next layer is made up of Basalt

which is found in oceanic crust and continental crust

if we are going to compare the mass of oceanic crust and continental crust, oceanic crust is the heaviest.

here is a table that shows the element composition of our crust

we will end here our discussion on the concentric layers of the earth

on our next episode we will discuss the fifth concentric layer

which is the atmosphere

so if you have questions on the concentric layers that we discussed earlier,

just leave a message below

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