The Origin and Evolution of Earth - Chapter 2 Geography NCERT Class 11
Summary
TLDRThis educational video delves into the formation and evolution of Earth, exploring both early and modern theories. It discusses the universe's expansion, the formation of stars and planets through accretion and gravitational forces, and the solar system's structure. The video also covers the Earth's layered structure, the evolution of its atmosphere and hydrosphere, and the origin of life. It highlights the significance of photosynthesis in creating Earth's oxygen-rich atmosphere and the geological timeline that traces life's development from simple organisms to complex life forms.
Takeaways
- 🌏 The Earth's formation and evolution are central to understanding its origin and the physical changes it underwent over time.
- 🌌 Two main theories exist for the origin of Earth: early and modern, with separate videos explaining each theory in detail.
- 📈 The universe is expanding, with an increase in space between galaxies, and our solar system is part of the Milky Way galaxy.
- 🌌 Stars were formed around 5 to 6 billion years ago, prior to the formation of planets, through the process of fusion where hydrogen and helium atoms combine, releasing energy.
- 🌍 Planets formed from localized lumps of gases that, due to gravitational force, created a core and a rotating disk of gas and dust, eventually leading to the formation of planets.
- 🌐 The solar system consists of the Sun, eight planets, moons, asteroids, comets, and other celestial bodies, with terrestrial planets being closer to the Sun and Jovian planets further away.
- 🌘 The difference between terrestrial and Jovian planets lies in their composition and proximity to the Sun, with terrestrial planets being rocky and Jovian planets being gas giants.
- 🌕 The Moon, Earth's only natural satellite, is believed to have formed from a giant impact, where a Mars-sized object collided with Earth, ejecting debris that coalesced into the Moon.
- 🌋 The Earth's layered structure, including the crust, mantle, outer core, and inner core, resulted from the process of accretion and the separation of materials based on density.
- 🌬️ The evolution of Earth's atmosphere and hydrosphere involved stages such as the primordial atmosphere, volcanic activity releasing gases, and the formation of oceans, which allowed life to evolve.
- 🌱 The origin of life on Earth is attributed to complex chemical reactions that led to the formation of organic molecules capable of self-replication, eventually giving rise to all life forms.
Q & A
What are the two theories about the origin of Earth mentioned in the video?
-The two theories about the origin of Earth mentioned are the early and modern theories. The video creator has made separate videos on both, which are linked in the description for further understanding.
What is the significance of the universe's expansion in relation to galaxies?
-The expansion of the universe refers to the increase in space between galaxies. It's important to remember that a universe consists of more than one galaxy, and each galaxy contains moons, asteroids, planets, and stars. The solar system we are part of is one such galaxy, and the Milky Way is the name of our galaxy.
How long ago are stars believed to have been formed, and how does this relate to the age of Earth?
-Stars are believed to have been formed about 5 to 6 billion years ago. Since Earth is estimated to be 4.6 billion years old, it's clear that stars were present before the formation of planets.
What is the process called where two light nuclei combine together, releasing a vast amount of energy?
-The process where two light nuclei combine together, releasing a vast amount of energy, is called fusion reaction.
Can you explain the formation of a core in a gas cloud as described in the video?
-The formation of a core in a gas cloud is described using the example of spinning a bucket of water with sand in it. The sand particles gather at the center due to the centrifugal force, similar to how the core of a gas cloud forms due to gravitational forces within the cloud.
What is the difference between terrestrial and Jovian planets?
-Terrestrial planets are those that lie between the Sun and the asteroid belt, composed mainly of rock and metal. Jovian or gas giant planets are those outside the asteroid belt and are characterized by their thick atmospheres of helium and hydrogen.
Why does the Earth's atmosphere contain mostly nitrogen and oxygen?
-The Earth's atmosphere contains mostly nitrogen (about 78%) and oxygen (about 20-21%) due to a series of evolutionary stages, including the initial composition after the formation of the Earth, the effects of volcanic activity and degassing, and the introduction of oxygen through photosynthesis by early life forms.
How were the Earth's oceans formed according to the video?
-The Earth's oceans were formed as the planet cooled down, releasing gases and water vapor from its interior. Volcanic eruptions contributed to the continuous release of water vapor, which condensed and rained down, collecting in depressions to form oceans.
What is the 'Big Splat' theory mentioned in the video regarding the Moon's formation?
-The 'Big Splat' theory suggests that the Moon was formed as a result of a giant impact, where a Mars-sized object collided with the Earth. The debris from this collision eventually coalesced due to gravitational attraction to form the Moon.
How does the video explain the origin of life on Earth?
-The video explains that the origin of life on Earth is attributed to complex chemical reactions that generated complex organic molecules. These molecules were capable of duplicating themselves, leading to the formation of living organisms from inanimate matter.
Outlines
🌏 Origin and Evolution of Earth
This paragraph introduces Chapter 2, which discusses the formation and evolution of Earth. It mentions two theories regarding Earth's origin: early and modern, with separate videos provided for further understanding. The script explains the expansion of the universe and the structure of galaxies, including our own Milky Way. It also delves into the formation of stars around 5 to 6 billion years ago, which is prior to the formation of Earth, estimated at 4.6 billion years old. The process of star formation involves the fusion of hydrogen and helium atoms, releasing energy. The video also covers the measurement of light and the stages of planet formation, including the aggregation of gas clouds into cores and the eventual development into planets through accretion.
🚀 Formation of Solar System and Planets
Paragraph 2 elaborates on the formation of the solar system, starting with the nebula core around 5 to 5.6 billion years ago, leading to the formation of planets 4.6 billion years ago. The solar system is composed of the Sun, eight planets, moons, asteroids, comets, and other celestial bodies. Inner planets (Mercury, Venus, Earth, Mars) are distinguished from outer planets (Jupiter, Saturn, Uranus, Neptune), with the latter also known as Jovian or gas giant planets. The paragraph explains the difference between terrestrial and Jovian planets based on their composition and proximity to the Sun. It also touches on the theory of moon formation, suggesting that the current scientific consensus is that the Moon was formed from debris after a large body the size of Mars collided with Earth, known as the Giant Impact Theory or Big Splat.
🌋 Earth's Layered Structure and Evolution
Paragraph 3 discusses the evolution of Earth from a hot, rocky object with a thin atmosphere to its current state. It highlights the layered structure of Earth, including the crust, mantle, outer core, and inner core. The process of accretion, which led to the formation of Earth's layers, is explained, along with the role of temperature and density in material separation. The paragraph also covers the formation of the Moon and its impact on Earth's evolution, including the Giant Impact event. Additionally, it provides an overview of the lithosphere, which includes the crust and mantle, and how the Earth's early volatile state led to constant changes and the eventual formation of a crust.
🌤️ Evolution of Atmosphere and Hydrosphere
This paragraph details the evolution of Earth's atmosphere and hydrosphere. It describes the initial atmosphere composed mainly of hydrogen and helium, which was later lost due to solar winds. The current atmosphere's composition, dominated by nitrogen and oxygen, is a result of three stages: the premod atmosphere from the supernova explosion, the thermal radiation from Earth's hot interior, and the photosynthesis process by early life forms. The paragraph also explains the process of degassing, where gases and water vapor were released as Earth cooled, leading to the formation of oceans. The oceans are estimated to be around 4 billion years old, and their formation marked the beginning of life on Earth, which evolved in the oceans before spreading to land.
🌱 Origin of Life and Geological Time Scale
Paragraph 5 explores the origin of life on Earth, suggesting it began as complex chemical reactions that led to the formation of organic molecules capable of self-replication. These molecules transformed inanimate matter into living organisms. The paragraph connects the presence of fossils in rocks to the early life forms, such as blue algae, indicating life evolved around 3.8 billion years ago. It mentions the geological time scale, which charts the major events in the history of life on Earth, and how it shows the transition from unicellular bacteria to modern humans. The speaker expresses fascination with these processes and considers creating additional content to delve deeper into these topics.
Mindmap
Keywords
💡Origin of Earth
💡Evolution
💡Universe Expansion
💡Formation of Stars
💡Accretion
💡Terrestrial Planets
💡Jovian Planets
💡Moon Formation
💡Atmosphere Evolution
💡Origin of Life
Highlights
The chapter discusses the origin and evolution of Earth, including its formation and physical changes over time.
Two main theories on the origin of Earth are presented: early and modern theories, with separate videos provided for further understanding.
The universe is expanding, with an increase in space between galaxies, and our solar system is part of the Milky Way galaxy.
Stars are believed to have formed around 5 to 6 billion years ago, prior to the formation of planets like Earth.
Matter and energy in the universe were unevenly distributed, leading to the formation of hydrogen and helium atoms through fusion reactions.
The formation of planets involves stages such as core formation, gas cloud condensation, and the development of planetesimals into planets.
Our solar system consists of the Sun, eight planets, moons, asteroids, comets, and other celestial bodies.
The terrestrial planets (Mercury, Venus, Earth, Mars) are rocky and metallic, while Jovian planets (like Jupiter) are gas giants.
The Moon is Earth's only natural satellite, and its formation is believed to be the result of a giant impact.
Earth's early atmosphere was different from today's, consisting mainly of hydrogen and helium.
The evolution of Earth's atmosphere involved stages including the primordial atmosphere, volcanic outgassing, and the addition of oxygen through photosynthesis.
The oceans on Earth formed around 500 million years after the planet's formation, providing a habitat for the earliest life forms.
Life on Earth is thought to have originated from complex chemical reactions that led to self-replicating organic molecules.
The geological timescale provides a framework for understanding the major events in the evolution of life on Earth.
The chapter concludes by emphasizing the importance of understanding the origin and evolution of life as a crucial part of Earth's history.
Transcripts
this video is about chapter 2 the origin
and evolution of Earth in this chapter
we will read about the story of the
origin that is the formation of Earth
and evolution that is how Earth evolved
over time meaning what were the physical
changes that the Earth went through now
the origin of Earth has two theories
basically the early and modern theories
I've made separate videos on both the
theories I'll be posting the link in the
description as well as you can click on
the link here on the screen so watch
that video and you will understand these
theories well the expansion of universe
means increase in space between the
galaxies always remember this order a
universe consists of more than one
Galaxy and one Galaxy consists of moons
asteroids planets and stars so the solar
system that we are part of is one Galaxy
like that there are many other galaxies
and the name of a galaxy is Milky Way
though we know there are many other
galaxies but we do not know whether
there is another universe so the
scientific Community only believes in
the theory that the universe is
expanding
now we will read about how the stars
were formed now the formation of stars
is believed to have taken place some 5
to six billion years ago Earth is
believed to be 4.6 billions years old so
clearly stars were there before the
planets previously we spoke about how
matter and energy was scattered in the
universe due to the big explosion of the
singular atom one thing to know is that
the matter and energy were uneven
meaning there were differences in the
densities in every matter because of
that there was attraction between these
matters and that's how hydrogen and
helium atoms were formed basically
hydrogen and helium are a gas like this
there are many tiny groups of hydrogen
and helium gases constantly colliding
with each other and producing energy
this process is also called as fusion
reaction where two light nuclei combined
together releasing vast amount of energy
and this energy gave rise to formation
of stars let's quickly understand how to
measure a light here again I've made a
separate video on this topic as well the
link is there in the description you can
also click on The annotation on the
screen so follow the link and watch the
video now we are going to talk about the
formation of planets now there are again
some stages in the development of
planets as well so let's go through them
so just moments back we have read that
stars are localized lump of gases now
the gravitational force within those
lump leads to the formation of a core to
the gas cloud and a huge rotating disc
of gas and dust envelopes around the gas
core
so let me just show it to you with the
help of an illustration because it's
very difficult to make you understand
with words so a good example to
illustrate this is uh take a bucket of
water a little water not much and put
some sand in it now spin the water in
that bucket in a circular fashion soon
you'll notice that so all the mud
particle that you had poured it will
come in the center and gather so that's
how it forms a core and the same thing
happens in these gas clouds inside a
star and then after a long time layers
of of layers starts forming and that's
how a rotating dis of gas is formed and
then in the next stage the gas cloud
starts getting condensed meaning it gets
very concentrated and due to this
phenomena the matters that are around
the core develops into small rounded
objects then again after time what
happens these small objects by the
process of cohesion meaning they form
group sort of a thing and develops into
what is called Planet decimal
so you see most of the things happen
because of collision and gravitational
attraction because of these phenomena
the materials stick together and that's
what makes these large number of small
bodies now in the final stage these
large number of small bodies they
accrete to form a few larger bodies so
the meaning of accrete is forming layer
after layer so these smaller bodies that
were formed due to Collision and
gravitational attraction with time what
happens is layers several layers are
formed on it as a result from a small
body it becomes a large body and that's
how planets are formed I hope you
understood somewhat how the planets are
formed if at all you did not follow up I
recommend that you go back a little bit
and watch it again because it can get
difficult to explain by using these
words that are given in the book so I'm
trying my best to use illustrations and
examples and you know refining the words
into simpler terms so just go back a
little bit and watch it again and I'm
sure you'll get get it now we're going
to read about our solar system so here
it says our solar system consists of
nine planets now this is a fairly old
book so as of now there are eight
planets in the solar system so that
means Pluto is no longer a planet and
the reason behind that is because it has
been classified as dwarf so the meaning
of dwarf planet is it is a round mass of
metal and rock or gas moving around the
Sun that is not large enough to be
considered as as a planet okay some of
the 12w planet in our solar system
includes Pluto then we have series and
Aries so as I've told you before that
everything right from planets and stars
and everything has been formed out of
this Cloud called nebula so the core
formation of this nebula started
somewhat around 5 to 5.6 billion years
ago and the planets were formed about
4.6 billion years ago so clearly it
means that stars were there before
planets now don't forget this just
remember this our solar system consists
of sun that is the star sun is a star
basically and then we have eight planets
then 63 moons then millions of smaller
bodies like asteroids and comets and
huge quantity of dust grains and gases
and if you see it is because of these
two last terms that is dust grains and
gases there are new stars and planets
that are coming up so there's always a
new discovery by NASA about all these
planets and stars so out of the eight
planets Mercury Venus Earth and Mars are
called as the inner planet so if you
look at the solar system after Mars the
Jupiter planet comes and in between Mars
and Jupiter there is a big asteroid belt
so those planets which are out of
asteroid belt including Jupiter they are
known as outer planets and those which
are inside they are called inner planets
so these planets which are inside the
asteroid belt they are called as
terrestrial planets meaning they have
earthlike
similarities in other words they consist
of rock and metals and the planets that
are outside the asteroid belt they are
called Jovian or gas giant planets so
basically they are like Jupiter and they
are huge planets but they have very
thick atmosphere mostly of helium and
hydrogen and this is another cool fact
all the planets were formed in the same
period sometime about 4.6 billion years
ago so when we hear something like this
that all the planets were formed in the
same period it clearly proves the fact
that whatever phenomena that caused
these planets to exist is actually true
which is the Big Bang Theory the
universe being expanding whilea Theory
because just for argument sake had it
been the fact that all the planets came
into existence at their own time then it
would be difficult to argue that what
actually happened because there there's
going to be very different kind of data
of you know something happened because
of something else and then something
happened because of something else if
everything happens because of one reason
then it is easier to study and
understand I hope you're getting what
I'm trying to say now let's try to
understand what is the difference
between terrestrial and Jovian Planets
so let me quickly tell you this
terrestrial planets are those planets
which are in between the Sun and the
asteroid belt and the ones that are
outside the asteroid belt they are known
as Jovian planets or outer planets so as
we know that most of the testile planets
are full of rock and
so that means it has very less gas and
dust and if you look at the Jovian
Planets they have lot of gas present
dust and gas present so the theory goes
like this Newton realized that the
reason the planets orbit around the Sun
is related to why objects fall to earth
when we drop them the Sun's gravity
pulls on the planets just as Earth's
gravity pulls down anything that is not
held up by some other force and keeps
you and me on the ground so heavier the
objects produce a bigger gravitational
pull than lighter ones so as the heavy
weight in our solar system the sun is
the strongest gravitational pull now
with this Theory you know that the
terrestrial planets which are between
the Sun and asteroid belt they are
nearer to the Sun and because of that
they exert a lot of gravitational pull
and because they are nearer to the sun
meaning the heat of the sun blew away
all the gases and dust but then the
Jovian planets which are outside the
asteroid belt they are far away from the
Sun so the solar winds were not that
intense that's why these planets still
have a lot of gas and dust particles so
that's the reason between the inner
planets and the outer planets or in
other words the terrestrial planets and
the Jovian
Planets now we're going to talk about
the moon moon is the only natural
satellite of the earth meaning Moon just
revolves around the earth now there is a
theory behind how the moon was formed so
if you see a lot of the time we are
reading about theories in this chapter
so this chapter is full of theories so
let's understand the theory behind the
moon as well so in 1838 Sir George
Darwin he suggested that the Earth and
the moon they were combined okay they
were joined together like a dumble
shaped so if you have seen a dumble it
looks like this now what happened was it
eventually broke and the material that
was forming the Moon it got separated
from the earth and to support this
Theory Darwin went on to say that if you
look at the depression in the Pacific
Ocean so Pacific Ocean is the largest
ocean and the deepest ocean so the
depression that occupies the Pacific
Ocean that depression is due to the
separation of the Moon object from the
earth so this is the theory of George
Darwin now the present scientist they do
not accept this Theory what we now
believe is that the formation of moon as
a satellite of Earth is an outcome of
giant impact now this theory has another
name which is called the big Splat now
big splat that means Big Splash a giant
impact now what this Theory says is
there was an object of the size of Mars
so that object that body it collided
into the Earth sometime shortly after
the earth was formed so when two objects
Collide there are these debris so these
portions of small blasted material they
continue to orbit around the Earth and
due to gravitational attraction and
collision these small particles
eventually formed into the present Moon
so this theory is now widely accepted
about the origin of moon now we're going
to read about the evolution of the earth
so once upon a time the planet Earth was
a baring Rocky and hot object with a
thin atmosphere of hydrogen and helium
and today when we see a picture of the
Earth it does not look like that so
obviously there must have been some
events some processes which has caused
this change so let's go ahead and
understand what led to the evolution of
life on the surface of the planet
so we know that all the celestial body
were formed with a process called
accretion meaning a layer after layer
after layer that's how they became from
small body to a large body similarly
Earth is no different the Earth has a
layered structure so from the outermost
end of the atmosphere to the Center of
the Earth the material that exists is
not uniform meaning they are not same so
right from the outside of the earth as
we go towards the interior of the Earth
the density increases
that's why we also know that there are
five layers in atmosphere and then we
also know that the Earth's interior is
divided into four parts that is the
crust mantle outer core and inner core
and that's why in geography we also have
different disciplines to understand the
Earth we have the lithosphere then we
have the study of atmosphere hydrosphere
so they have been nicely categorized in
different subjects so that we can read
about Earth in a much more better sense
now we are going to read about
lithosphere when we hear the word
lithosphere it it means the outer layer
of the Earth consisting of crust and
mantle so initially the Earth was in a
volatile State meaning there was
constant change taking place everything
was going through Rapid change so all
the particles that were involved in the
creation of Earth their densities were
increasing as well there was so much
Collision taking place and energy was
increasing as a result temperature was
also increasing rapidly in chemistry if
you want to extract or refine any metal
you need to put the metal in a furnace
where the temperature is extremely high
the idea is to turn the metal into a
molten state so that the properties of
the metal get separated similar thing
happened here as well when the
temperature was so high all the
materials started getting separated
depending on their densities heavy
materials like iron started sinking
towards the center of the earth forming
the coal and the lighter ones moved
towards the surface with time the
temperature cooled and the outer layer
in the form of a crust was formed and
then there was another big impact that
is the cre creation of moon which we
also call the giant impact even that
further heated the Earth and that's how
materials got separated into different
layers we know Earth has four layers
like the crust mantle outer core and
inner core always remember from the
crust to the core the density of the
material increases in the coming
chapters we will discuss about the
properties of each of the Earth's layer
now we're going to read about the
evolution of atmosphere and hydrosphere
so in the Earth's atmosphere you will
mostly find nitrogen and oxygen nitrogen
consists of some 78% of the entire air
and 20% or 21% is oxygen there is a
separate chapter that is chapter 8 which
deals with the composition and structure
of Earth's atmosphere so we will read in
depth about all these things in that
chapter so there are three stages in the
evolution of the present atmosphere it
is because of these three stages the
present atmosphere came into being so in
the premod atmosphere the Sun and its
planet formed about 5 billion years ago
where there was an explosion of a
supernova which is a big star so that
before bursting had generated heavy
elements starting from hydrogen and
helium so that was the first stage of
the present atmosphere I mean to say
atmosphere initially looked like that
and then comes the second stage we have
read that the Earth was a very volatile
object there were constant changes rapid
development was going on and the
temperature was so high that the
interior of the Earth was super hot so
when an object is super hot it will emit
heat which is also called as thermal
radiation so we have to say that these
thermal radiation they will also
contribute to the evolution of the
atmosphere so every single aspect
together contributed towards present
atmosphere that's why we have to count
every single thing and now comes the
final stage that is the third stage
today when human beings and living
organism came into existence in this
world there was a process called photo
synthesis so photosynthesis is a
chemical process through which plants
some bacteria and algae produce glucose
and oxygen from carbon dioxide and water
using only light as a source of energy
before even humans arrived on this
planet There Were Trees plants and all
sorts of grasses and Etc so we can say
that the process of photosynthesis has
already begun before the humans arrived
and we know that plants take carbon
dioxide and emits oxygen so again there
is a emission of oxygen involved and
that is the final and the third stage of
the composition of present atmosphere
always remember the premod atmosphere
which is the initial atmosphere when the
Earth was beginning to form that
atmosphere consisted only of hydrogen
and helium so that atmosphere went away
and the reason behind that is because it
is not just Earth all the terrestrial
planets so we have spoken about what the
terrestrial planets are these are the
planets that are in between Sun and and
the asteroid belt so basically there are
only four planets Mercury Venus Earth
and Mars now these planets the
terrestrial planets since they are
closer to the Sun these planets received
a lot of solar wind coming from the Sun
it stripped off the hydrogen and helium
atmosphere and that's why these planets
don't look like the jovial planets the
planets which are outside the asteroid
belt and finally when the Earth was
cooling down the gases and the water
vapor they were released from the
interior of Earth now this thing is very
easy to imagine whenever you're trying
to boil water in an utensil at your
place you will see that if you put a
cover on it or if you put some kind of a
plate on it you'll see that the plate
will gather all the water vapor so the
similar thing happened when the Earth
was cooling down all the heat was
released upward and in the atmosphere
the water vapor was collected and that
is how the present atmosphere started
the early atmosphere largely contained
water vapor nitrogen carbon dioxide
methane ammonia and very little of free
oxygen so the process through which the
gases were outpoured from the interior
is called degassing now you must be
wondering that okay the gases were
degased so how did it still continue to
form water vapor and the answer to that
question is the continuous volcanic
eruption so volcanoes are like a
ventilator of the earth so from these
ventilators the inner core the heated
substance of the earth starts pouring
out and again if there is a a substance
which has a high temperature there will
be heat and because of this continuous
volcanic eruption there was a lot of
water vapor and gases generated and as
these water vapor were released they
started getting condensed and then the
carbon dioxide in the atmosphere got
dissolved in rain water and the
temperature further decreased causing
more condensation and rain and then once
rain started happening the rain water
falling onto the surface got collected
in the depression to give rise to oceans
and that's how the ocean iodes of the
earth were formed so these Earth's ocean
were formed within 500 million years
from the formation of the earth now that
tells us that the oceans are as old as
4,000 million years and then once the
oceans were formed life began to evolve
and if you notice bacteria were among
the first life forms to appear on Earth
and if you see humidity is perfect for
any bacterial growth and humidity is
formed due to heat and water hence it is
obvious that once the oceans were formed
L life began to evolve and once life
began to evolve the process of
photosynthesis also started so for a
very long time life was confined to the
oceans that means there was no presence
of life on a land form it was only
confined to Ocean because ocean had the
perfect combination of oxygen through
the process of
photosynthesis and eventually this big
ocean was saturated with oxygen and
after that oxygen began to flood to the
atmosphere and that's how oxygen contain
started increasing in the atmosphere now
comes the last topic of this chapter the
origin of life because once the earth
was formed it is necessary to know about
the life on Earth otherwise the entire
big picture is incomplete that's why the
origin and evolution of life is regarded
as the last phase in the evolution of
Earth so far after reading all of this
we are clear about the fact that
initially it was impossible to live on
Earth because the conditions were not
ideal you know Earth was w vertile it
was super hot there was very little
oxygen so all these things were going on
hence the modern scientist they think
that the origin of life is due to the
complex chemical reaction that generated
complex organic molecules and because of
their assembly we came into present and
this assembly of complex organic
molecules is such that it duplicates
themselves it is just like amoeba how it
splits into two equal copies of itself
similarly this organic molecule it
started copying itself and that got
converted into inanimate matter and that
converted some matters which were
lifeless which had no sign of life into
living organism so when you look at a
rock you'll find fossils in it fossils
are the dead decay of animals and plant
organism hence when we look at a rock
the record of life that existed on this
planet can be seen across different
periods so when you look at Blue algae
which is found in lakes and water bodies
and if you look at the microscopic
structure closely you will find that
these formations are present in rocks
that are much older and are some 300,000
million years ago and that is how we can
assume that life began to evolve
sometime 3,800 million years ago and if
you want to know how a unicellular
bacteria turned into a modern man then
you have to look at this geological time
scale so this geological time scale
shows some life major events and it is
very fascinating to see how this thing
happened it is almost like a magic but
there's a huge deep science involved and
that is why it makes geography
interesting you know I'm so fascinated
to read all of this maybe I will make a
separate short videos on these smaller
Concepts as to how human came into
existence how Earth was formed how this
ocean were formed moon were formed Etc
anyways with this we have come to an end
of this chapter and this chapter has
been a real eye opener till now for me
and it's so interesting and fascinating
to read this I hope you understood
whatever that I told you though in
between it was kind of difficult for me
to comprehend because the words that
were used they were not very simple to
be able to convert them into a real
metaphor or a simpler example I hope you
found this video informative and let me
know what you think about this so as
usual question answers can be found on
the website so 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
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