Interior of the Earth - Chapter 3 Geography NCERT Class 11

Summary

This educational video script delves into the Earth's interior, exploring its layers—core, mantle, and crust—and the dynamic processes within. It distinguishes between endogenous forces like volcanic activity and exogenous ones such as erosion, shaping our landscapes. The script underscores the significance of understanding these processes for human settlement and disaster mitigation. It also discusses how scientists gather information about the Earth's interior through direct observations, like deep drilling, and indirect methods, including gravitational anomalies. The video concludes with an overview of earthquake types, their measurement, and effects, promising further exploration in linked videos.

Takeaways

• 🌏 The interior of the Earth consists of the core, mantle, and crust, which are in a constant state of change.
• 🌋 Endogenous processes such as volcanic activity and tectonic plate movements shape the Earth's landscape, while exogenous processes like weathering and erosion modify its surface.
• 🏙️ Population density is higher in flat areas due to the influence of physiographic conditions on human settlement.
• 🌪️ Understanding the Earth's interior helps in predicting and mitigating the impact of natural disasters like earthquakes and tsunamis.
• 🔍 Direct observation of rocks and analysis of materials from deep drilling and volcanic eruptions provide insights into the Earth's interior.
• 📊 Indirect sources of information about the Earth's interior include temperature, pressure, and density changes with depth, as well as meteorite studies.
• 📉 Gravity anomalies indicate variations in the Earth's mass distribution, with higher gravity at the poles suggesting greater mass concentration.
• 💥 There are different types of earthquakes, including tectonic, volcanic, collapse, explosion, and reservoir-induced, each with unique causes and effects.
• 📈 Earthquakes are measured using the Richter scale for magnitude and the Mercalli scale for intensity.
• 🌋 Volcanoes release magma from the asthenosphere, leading to various volcanic landforms and the release of gases and pyroclastic materials.

Q & A

What are the three main layers of the Earth's interior?

The three main layers of the Earth's interior are the core, mantle, and crust.

What are endogenous processes and how do they affect the landscape?

Endogenous processes are internal geological activities such as volcanic activities, folding of the crust, and faulting due to plate tectonic activities. These processes change the landscape by shaping the Earth's surface features.

How do exogenous processes contribute to changes in the landscape?

Exogenous processes are external activities like weathering, erosion, transportation, deposition, and denudation. These processes alter the outer physical shape of a landscape by wearing down and reshaping the Earth's surface.

Why is it important to understand the interior of the Earth in relation to human settlements?

Understanding the interior of the Earth is important because human settlements are largely based on the physiographic conditions of a region. Knowledge of these conditions can help predict and mitigate risks from natural calamities such as floods and landslides.

What are the two ways scientists collect information about the Earth's interior?

Scientists collect information about the Earth's interior through direct observations and analysis of materials. This includes studying rocks from the surface and mining areas, as well as materials that come out from the interior, such as magma during volcanic eruptions.

What is the significance of the Cola deep drill in Arctic Ocean?

The Cola deep drill in the Arctic Ocean is significant because it is the deepest drill to date, reaching a depth of 12 km. This is an important effort to gather information about the Earth's interior, although it is still only half the depth of the continental crust.

How do indirect sources of information contribute to our understanding of the Earth's interior?

Indirect sources of information, such as changes in temperature, pressure, and density with depth, meteorites, and variations in the Earth's gravitational field, contribute to our understanding of the Earth's interior by providing data that scientists can analyze to estimate the conditions within the Earth.

What are the different types of earthquakes mentioned in the script?

The script mentions five types of earthquakes: tectonic, volcanic, collapse, explosion, and reservoir-induced earthquakes.

How are the strength and intensity of an earthquake measured?

The strength or magnitude of an earthquake is measured using the Richter scale, while the intensity is determined by the Mercalli scale, which ranges from 1 to 12.

What is the role of the asthenosphere in volcanic activity?

The asthenosphere, part of the upper mantle, contains molten rock called magma that moves and causes instability in the crust. This movement can lead to seismic activities and is the source of magma that erupts from volcanoes as lava.

Outlines

00:00

🌍 Understanding Earth's Interior

This paragraph delves into the concept of Earth's interior, encompassing its core, mantle, and crust. It emphasizes the significance of comprehending the constant changes within Earth's layers for grasping landscape dynamics. The distinction between endogenous (internal processes like volcanic activities and plate tectonics) and exogenous (external processes like weathering and erosion) processes is highlighted. The paragraph also underscores the relevance of this knowledge for human settlements, especially in the context of natural disasters. It introduces the methods of studying Earth's interior, such as direct observations from rocks and materials from deep drilling projects and volcanic eruptions, and indirect observations like temperature, pressure, and density changes with depth.

05:02

🌐 Indirect Sources of Earth's Interior Information

The second paragraph focuses on indirect sources that provide insights into Earth's interior. It discusses how temperature and pressure increase with depth, and how density changes are observed through mining activities. The paragraph also mentions the use of meteorites as a source of information, given their composition is similar to Earth's materials. Gravitational anomalies, magnetic fields, and seismic activities are highlighted as crucial indirect sources. The concept of gravity anomalies is explained, linking it to the Earth's shape and material distribution. The paragraph transitions into a discussion on the types of earthquakes, their causes, and the tools used to measure them, such as seismographs, and the Richter and Mercalli scales.

10:02

🌋 Earthquakes and Volcanic Landforms

The final paragraph addresses the effects of earthquakes on landforms and human life, detailing the various consequences of seismic activities. It distinguishes between high-magnitude earthquakes that are rare but highly destructive and the more frequent, low-magnitude tremors. The structure of the Earth is briefly mentioned, with a reference to a separate video for detailed information. The paragraph then shifts to volcanoes, explaining the origin of magma and the materials emitted during volcanic eruptions. Different types of volcanoes and their landforms are introduced, with a prompt to view another video for a comprehensive understanding. The paragraph concludes by summarizing the chapter's coverage of Earth's interior and encourages viewers to explore the provided resources for further learning.

Keywords

💡Interior of the Earth

The 'Interior of the Earth' refers to the layers beneath the Earth's surface, including the core, mantle, and crust. This concept is central to the video's theme as it sets the stage for discussing the Earth's structure and the processes occurring within it. The video mentions that understanding the interior is crucial for comprehending the changes and activities that shape the Earth's surface.

💡Endogenous processes

Endogenous processes are internal geological activities such as volcanic eruptions, folding of the crust, and faulting due to plate tectonics. These processes are highlighted in the video as they are responsible for changing the landscape and are a key aspect of understanding the Earth's interior dynamics.

💡Exogenous processes

Exogenous processes are external forces that act upon the Earth's surface, such as weathering, erosion, transportation, deposition, and denudation. The video explains that these processes alter the physical shape of landscapes and are distinct from endogenous processes in that they operate on the surface rather than within the Earth.

💡Physiographic conditions

Physiographic conditions refer to the physical features of a region, such as its topography and landforms. The video discusses how human settlements are largely based on these conditions, with populations tending to be higher in plains areas compared to hilly or mountainous regions due to the influence of physiographic conditions on habitability.

💡Natural calamities

Natural calamities, such as floods and landslides, are mentioned in the video as events that pose significant risks to human life and property. Understanding the interior of the Earth and the processes that lead to such calamities is emphasized as a way to develop protective mechanisms against them.

💡Direct observation

Direct observation is a method of collecting information about the Earth's interior by studying rocks from the surface and mining areas. The video explains that while direct observation has its limitations, it provides valuable insights into the composition and characteristics of the Earth's layers.

💡Volcanic activities

Volcanic activities are cited in the video as a source of direct information about the Earth's interior. When magma is erupted from a volcano, it offers scientists a sample to analyze and infer the conditions and materials present at deeper levels within the Earth.

💡Gravity anomaly

A gravity anomaly is a change in gravitational force that varies with location on Earth. The video explains that gravity is greater near the poles and less at the equator, which can be attributed to the Earth's non-spherical shape and the distribution of mass within the planet.

💡Tectonic earthquakes

Tectonic earthquakes result from the breaking of the Earth's crust due to the sliding of rocks and the creation of faults. The video discusses this type of earthquake as a common one, directly related to the movement and interaction of tectonic plates within the Earth's crust.

💡Seismograph

A seismograph is an instrument used to detect and measure earthquakes by recording vibrations. The video mentions seismographs in the context of measuring the strength or magnitude of earthquakes, which is crucial for understanding their impact and potential hazards.

💡Volcanic landforms

Volcanic landforms are geological features created by volcanic activity, such as lava flows, ash deposits, and craters. The video touches upon these landforms as a result of the interaction between the Earth's interior (specifically the asthenosphere where magma is generated) and the surface.

Highlights

The chapter explores the Earth's interior, including the core, mantle, and crust.

Understanding the Earth's interior is crucial for comprehending constant changes within the planet.

Landscapes are shaped by both endogenous (internal) and exogenous (external) processes.

Endogenous processes include volcanic activities, crust folding, and plate tectonics.

Exogenous processes involve weathering, erosion, transportation, and deposition.

Knowledge of the Earth's interior is vital for human settlements and understanding natural calamities.

The Earth's radius is 6370 km, and direct observations are limited due to inaccessibility.

Direct sources of information include rocks from the Earth's interior, such as those from mining.

Deep drilling projects, like the one in the Arctic Ocean, provide insights into the Earth's layers.

Volcanic eruptions offer another direct source of information through magma analysis.

Indirect sources of information include temperature, pressure, and density changes with depth.

Meteorites provide information about the Earth's interior as they are composed of similar material.

Gravitational anomalies indicate variations in Earth's mass distribution.

Tectonic earthquakes result from the breaking and sliding of the Earth's crust.

Volcanic earthquakes are associated with magma movement and pressure changes around volcanoes.

Collapse earthquakes occur in areas of intense mining activity due to underground mine roof collapses.

Explosion earthquakes are manmade, caused by the detonation of chemical or nuclear devices.

Reservoir-induced earthquakes happen in areas with large water reservoirs due to water pressure on the crust.

Seismographs measure earthquake vibrations, and the Richter scale quantifies their magnitude.

Earthquakes have various effects on landforms and human life, with high-magnitude events causing significant damage.

The chapter provides a comprehensive understanding of the Earth's interior and its impact on our world.

Transcripts

this chapter is about the interior of

the earth when we say interior we are

talking about the inside of Earth so if

you are familiar with this diagram the

different layers of earth that is the

core mantle and crust these all together

make the interior of the earth and there

is a constant change that is going on

inside the earth knowing those changes

requires us to understand the interior

of the earth that is what we are going

to learn in this chapter the landscape

that we see around us is a result of a

constant endogenous and exogenous

process

so endogenous means internal and

exogenous is external now internal

processes such as volcanic activities

folding of the crust and faulting due to

plate tectonic activities so all these

process change the landscape and they

are collectively known as endogenous

processes now exogenous process are

those activities like weathering erosion

Transportation deposition denudation all

these acts causes changes to the outer

physical shape of a

landscape the main reason it is

important to know about the interior of

the earth is due to the fact that human

settlement is largely based on

physiographic conditions of a region

that's why you'll see in plain areas the

population is more compared to hilly and

mountainous region now we have seen a

lot of times due to natural calamities

like flood Landslide there's a huge risk

towards human life as well as properties

and if we know why the Earth shakes or

how a tsunami wave is generated that

will help us in creating necessary

mechanisms that will protect us from any

any of such natural calamities again

going back to this diagram about

different layers of earth scientists

have gathered enough information and

various characteristics about each of

these layers so this chapter will

basically help us know more about these

layers let's read some information about

the interior of our Earth the Earth's

radius is 6370 km and no one can reach

the center of the earth and it is

obvious as to why we cannot so in that

case we only have two ways of collecting

information about the interior of our

Earth and that is through direct

observations and Analysis of

materials first let's know about some

direct sources under direct sources we

have rocks that are like a strong

evidence which we can use to know the

interior of the Earth the rocks that we

see on the surface or the Rocks we get

from mining areas they all speak

something about the interior of the

Earth but it is generally said that if

we can get some rocks that are direct

from the interior we have better

information that will lead us some where

because the surface rocks undergo

constant weathering due to rain and wind

hence it is not as good as an interior

Rock from a mine that's why we have many

scientific projects around the world

that penetrate into deeper depth to

explore the conditions there are

projects like deep ocean drilling

project and integrated ocean drilling

project to gather large volume of

information and analyze materials for

understanding the interior of Earth just

a quick information here the the deepest

drill is at Cola which is in Arctic

Ocean and it has so far reached a depth

of 12 km the crust that is the upper

layer of the Earth is itself 30 km deep

from the continent not from the ocean

bed it is that thick so 12 km is just

half of it yet it has been the deepest

drill till date this is something to

think about so this was the drill part

for gathering information another way is

to analyze the material that comes out

automatically from the interior I'm

referring to the volcanic activities

volcanic eruption forms another source

of obtaining direct information so

whenever there is any volcanic eruption

a sample of the magma is tested around

the globe by scientists to determine its

components however it is difficult to

assume the depth of the source of such

magma meaning from where this magma has

evolved is it right from the core or is

it somewhere in between the Earth's

layers so there are some limitation when

the quest of knowledge is dependent on

Direct sources however it is far better

than going in person inside the earth

which can otherwise be

fatal now let's read about some indirect

sources that gives us information about

the interior so the temperature and

pressure increases as we go from the

surface towards the interior in deeper

depths now this information was observed

through mining activities another very

important information we know is that

the density of the material also

increases with depth now that we have

all all these facts scientists have

developed an estimation as to what the

temperature pressure and density of each

layer will be with respect to the total

thickness of the Earth again these are

estimation that is approximate values so

here you see a lot of mathematical

concept comes into play that's why it is

referred to as indirect sources another

source of information are the meteors

have you ever heard of meteor Shar

that's the time when meteors reach the

Earth since they are not part of Earth

you must realize that they are solid

bodies developed out of material similar

to that of Earth hence this becomes yet

another source of information about the

interior of the earth then other

indirect sources include gravitation

magnetic field and seismic activity so

gravitation force is not the same at

different latitudes it is greater near

the poles and less at the equator and

the reason is because the Earth is not a

perfect sphere it is bulged at its

Center so its distance from the Center

at the equator is comparatively more

than the poles the gravity keeps on

changing as we move from one place to

another but it is maximum at the place

where it is nearer to the center as a

result the gravity is more at the poles

and least at the equator now this change

in gravity reading is called gravity

anomaly the gravity values also differ

according to the mass of material and we

know that materials are unevenly

distributed on Earth moments back I told

you that gravity is more at the poles

than at equator therefore we can say

that the materials found at the pole

have higher Mass compared to the

materials found at equator and that's

why you will see North and South Pole

are rich in natural

resources the next topic is about

earthquake and I've made a separate

video on it I'll link the video in the

description and you can have a look at

it so now we are going to move on to the

topic types of earthquake the first one

is a common one and is known as tectonic

earthquakes whenever you to hear the

word tectonic we are referring to the

breaking of the crust part of the

Earth's surface so the breaking of the

crust part is due to Sliding of rocks

that creates a fault and that's what the

entire tectonic earthquake is all about

the second one is recognized as wanic

tectonic earthquake these are confined

to areas of active volcanoes now you see

this word tectonic again associated with

volcano so you know that volcanoes are

like a ventilator of the Earth's surface

from where the magma comes out whenever

the magma comes out of the volcano the

movement results in pressure changes in

the rock around where the magma has

experienced stress and at some point the

rock may break or move and when that

happens it's tectonic where in the crust

part of the Earth surface breaks

creating a fault the third one is called

as collapse earthquakes these take place

in areas of intense mining activity here

the roofs of underground mine collapse

causing minor tremors

as we know that mining involves a lot of

explosion of rock and that produces

seismic waves these waves are called

tors the fourth one is called explosion

earthquakes now by the word explosion

it's evident that we are talking about

something manmade or manually created

due to the explosion of chemical or

nuclear devices seismic waves are

produced and these waves produces

Tremors these Tremors move and break the

rocks and that creates an earthquake

which which is a total manually created

and the fifth one is Reservoir induced

earthquakes the earthquakes that occur

in the areas of large reservoirs are

referred to as Reservoir induced

earthquakes to explain this I'll have to

show you an illustration you know what a

reservoir is right now when reservoirs

store water and I mean large quantity of

water that huge quantity of water

creates pressure now where does the

pressure hits it hits on the wall the

surface of the reservoir

now those walls in turn creates pressure

on nearby rocks if at all there is a

fault meaning a crack in the crust

because you never know where the falls

and cracks are inside the crust so if at

all there is one nearby to the reservoir

that will push large chunk of rocks and

that fault may increase in size there

you go we have a reservoir induced

earthquake the next topic that we are

going to talk about is measuring

earthquakes a seismograph is used to

detect the vibration caused by an

earthquake the strength or magnitude of

an earthquake is measured using the

Richer scale on an intensity scale of 0

to 10 10 being the highest the intensity

of the earthquake is determined by a

merali scale which ranges from 1 to 12

so richer scale determines the magnitude

of the earthquake and mercal scale

determines the intensity of the

earthquake remember that now let's read

about the effects of earthquake

so earthquake is a natural Hazard so

these are some effects of earthquake I

want you to quickly look at them there

are some 10 to 12 of them just have a

look at them now in this list the first

six have to do with land forms because

if you see ground shaking differential

ground settlement land and mudslides

soil liquefaction then ground lurching

Avalanches all these have links with

land forms and the remaining effects of

this list are concerned with the life

and properties of people in that region

so yeah just have a look at this list of

some hazardous effects of

earthquake earthquake with high

magnitude can cause heavy damage to the

life and property of people and not all

the parts of the globe necessarily

experience major shocks a magnitude of 8

plus is very rare and can occur once in

1 to 2 years whereas those of tiny types

occur almost every minute so basically

it is saying that there is a constant

change that is happening inside the

surface of the Earth

and those little changes are creating

tiny

Tremors the next topic is about the

structure of the earth I've again made a

separate video on it the video link is

in the description please have a look at

it we now move on to the next topic

volcanoes and Volcanic landforms we all

know what a volcano is we have seen

pictures of it releasing gases ashes

then molten rock material lava to the

ground so the question now is where does

the magma inside the volcano comes from

so let's understand it with a simple

illustration below the volcano is the

crust which is the upper layer of the

Earth after crust it's the mantle

actually the mantle is divided into two

parts if you remember upper mantle and

lower mantle and we have also read that

the upper mantle is also called as

asthenosphere where ASO means weak here

the rocks are in molten fluid called

magma and is moving here and there and

that's what makes the crust unstable

causing seismic activities so it is from

this layer which is the astrosphere from

where the molten rock comes out of the

volcano as lava the material that

reaches the ground includes lava flows

pyroclastic debris volcanic bombs Ash

and dust and Gases such as nitrogen

compounds sulfur compounds and minor

amounts of chlorine hydrogen and argon

now volcanoes are of different types and

they are based on the nature of the

eruption and form I have another

separate video on different types of

volcanoes and their land forms the video

link is in the description just have a

look at it the reason I make topics like

these in separate videos so that they

can be referred easily by anyone at any

time you don't have to watch a long

video like this one and then get to a

point to understand one individual topic

so I hope you don't mind when I tell you

to go to so and so link for so and so

topic so don't forget to watch that

video as of now we are done with this

chapter this chapter dealt with the

interior of the Earth in a nice

comprehensive manner I hope you found

this video informative the question

answer of this chapter can be found on

the website the link is there in the

description as well as usual thanks for

watching and I'll see you in the next

one if you enjoy these videos and see a

purpose behind watching them please like

the video and comment down below until

then catch you guys later and talk to

you guys on the next one peace