3. Earth, otherwise known
as the world, is the
third planet from
the Sun and the only
object in
the Universe known to
harbor life. It is the
densest planet in
the Solar System and
the largest of the
four terrestrial planets.
- E A R T H -
4. *EARTH FACTS
The Earth formed 4570 million years ago (mya) but the first animals with
shells and bones appeared less than 600 mya. It is mainly with the help of
their fossils that geologists have learned about the Earth’s history since
then. We know very little about the 4000 million years before, known as
Precambrian Time.
Hot material from the Earth’s interior often bursts on to the surface from
volcanoes. 216
The Earth probably began when tiny pieces of space debris (called
planetesimals) began to clump together, pulled together by each other’s
gravity.
5. * F O U R ( 4 ) L AY E R S OF THE
E A R T H
Crust
Mantle
Outer Core
Inner Core
6. • Earth's crust. The crust
of the Earth is composed
of a great variety of
igneous, metamorphic, and
sedimentary rocks.
The crust is underlain by
the mantle. The upper part
of the mantle is composed
mostly of peridotite, a rock
denser than rocks common
in the overlying crust.
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- C R U S T-
7. * FACTS ABOUT THE EARTH’S CRUST
The crust is deepest in mountainous areas. It can be up to 70km thick
here.
The continental and oceanic crusts are bonded to the mantle, and this
forms a layer called the lithosphere. This layer is cool and rock solid.
The continental crust is solid and the temperature overall is about 22⁰C.
8. • The mantle is the mostly-
solid bulk of Earth's interior.
The mantle lies between
Earth's dense, super-heated
core and its thin outer layer,
the crust. The mantle is
about 2,900 kilometers (1,802
miles) thick, and makes up a
whopping 84% of
Earth's total volume.
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- M A N T L E -
9. * FACTS ABOUT THE EARTH’S MANTLE
The mantle of the earth is solid rock, but amazingly it can be
moulded, just like play dough. This certainly isn’t the type of play
dough you’d want to play with; your fingers would burn as it’s so
crazy, mad hot!
It is made of molten (melted) iron, minerals and other semi-solid
rocks that can flow under pressure.
thought that when the rocks rise due to the very intense heat and
then cool, this means that they sink back to the core and this
movement causes the crust to break into sections, or plates.
10. • The outer core of the Earth is
a fluid layer about 2,300 km
(1,400 mi) thick and composed
of mostly iron and nickel that
lies above Earth's solid
inner coreand below its
mantle. Its outer boundary lies
2,890 km (1,800 mi)
beneath Earth's surface.
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- O U T E R C O R E -
11. * FACTS ABOUT THE EARTH’S OUTER
CORE
Did you know that the inner core and the outer core of the Earth are as
big as Mars?
The outer core moves around the inner core, Earth's magnetism is
created.
The Outer Core is about 4000-5000 degrees celsius. The Inner Core is so
hot it causes all the metal in the Outer Core to melt into liquid magma.
12. • The Earth's inner core is
the Earth's innermost part and
according to seismological
studies, it has been believed to
be primarily a solid ball with a
radius of about 1,220
kilometres (760 miles), which is
about 70% of the Moon's
radius. It is composed of an
iron–nickel alloy and some light
elements.
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- I N N E R C O R E -
13. * FACTS ABOUT THE EARTH’S INNER CORE
Some scientists believe that the earth's inner core spins at a faster speed
than the rest of it - at a rate of 2/3rds of a second faster.
The Inner Core is a solid ball composed of an element named NiFe. Ni
for Nickel and Fe for Ferrum also known as Iron.
The Inner Core is about 5000-6000 degrees celsius. It melts all metal
ores in the Outer Core causing it to turn into liquid magma.
15. T R O P O S P H E R E
o The troposphere starts at the Earth's surface and extends 8 to 14.5
kilometers high (5 to 9 miles). This part of the atmosphere is the most
dense. Almost all weather is in this region.
16. S T R AT O S P H E R E
o The stratosphere starts just above the troposphere and extends to 50
kilometers (31 miles) high. The ozone layer, which absorbs and scatters
the solar ultraviolet radiation, is in this layer.
17. M E S O S P H E R E
o The mesosphere starts just above the stratosphere and extends to 85
kilometers (53 miles) high. Meteors burn up in this layer
18. T H E R M O S P H E R E
o The thermosphere starts just above the mesosphere and extends to 600
kilometers (372 miles) high. Aurora and satellites occur in this layer.
19. E X O S P H E R E
o This is the upper limit of our atmosphere. It extends from the top of the
thermosphere up to 10,000 km (6,200 mi).
