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SESSION 1
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Class 7
Ch.1 The Forces Beneath
Recapitulate how the earth was formed
Learn about the layers of the earth
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RECAP of Grade 6
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What you already know?
• Do you think landforms which we see today have undergone any
changes since their formation millions of years ago?
• YES to know more visit the following links
YouTube
https://www.youtube.com/watch?v=55oDyazPdTU
https://www.youtube.com/watch?v=uGcDed4xVD4
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Seismology & Seismologist
• Seismology is the study of earthquakes, volcanoes and related
phenomenon.
• Scientists who specialize in the study of earthquake and volcanoes by
studying the waves beneath the surface of the Earth are known as
Seismologist.
Recent Update –
Inner Earth is highly dynamic and chemically diverse.
The new view depicts the planet as a living organism
where events that happen deep inside effect the events
that take place on its surface.
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Layers of the Earth
• The Earth’s interior is made up of three concentric layers. Just like an
onion, it is made up of thin outermost skin known as crust, a thick
middle part called the mantle and the innermost part called the core.
• Crust :- It is the outermost layer of the Earth. It ranges in thickness
from 5km beneath the oceans to about 35kms on the continental
masses.
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Components of the Earth
Crust
Core
Mantle
Core
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EARTH’S CRUST
Crust
sial
Oceanic
Crust(Lower
Layer)
Silicon
Aluminium
sima
Continental
Crust(Upper
Layer)
Silicon
Magnesium
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Continental Crust and Oceanic Crust
Continental
Crust
Continent
Ocean
Oceanic
Crust
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MANTLE
• The mantle is about 2900 kms thick and is the densest part of the earth.
Mantle
Mantle is made up of solid
rocks and a layer of
molten rocks called
Magma.
Temperature –20000 C
Upper
Mantle
Lower
Mantle
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MANTLE CONSISTS OF :Rocks
Molten layer of Rocks
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CORE
• It is the innermost layer of the Earth & is about 2400 kms thick.
Core is composed of Iron, Nickel
and Sulphur.
Outer Core:
Temperature -40000 C to 50000 C
Core
Outer Core(in
liquid state)
Inner Core
Core (in solid
state)
Inner Core:
Temperature -50000 C to 70000 C
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MORE ABOUT CORE
Outer Core
Inner Core
• Temperature -40000 C to 50000 C
• Temperature -50000 C to 70000 C
• Added to this is the pressure
from all sides(as it is centre).
Therefore iron and other metals
cannot melt, and the inner core
remains solid in composition.
• Due to such extreme heat, the
minerals present in this layer are
in liquid or molten form.
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IP FOR THE DAY
1. List and present the characteristics of layers of Earth. Any
prop required to make the activity interesting may be
used. You may add interesting information and facts from
various sources.
2. Do Q.1 and Q.5 from the ‘Time to work out’ given on
page no.15.
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