Std-4 Ch-2

1. Day 1

2. THE MOVEMENTS OF
THE EARTH AND ITS
EFFECTS

3. Warm up
1) From where does the
sun rise?
2) From where does the
sun set?
3) Have you ever thought
why this happens?

4. Warm up
4) Why the earth appears
blue from space?
5) Which is the planet in the
solar system that has
life in the form of
plants, animals and
humans?

5. OUR PLANET—EARTH

6. OUR PLANET—EARTH
1. The earth is the only planet that has an
atmosphere containing about 21 percent
oxygen.
2. It is the only planet that has liquid water on its
surface and this is why the earth appears blue
from space.
3. It is also the only planet in the solar system that
has life in the form of plants, animals, insects,
birds and human.

7. The structure of the earth-video

8. THE STRUCTURE OF THE EARTH
• The earth was formed millions of years ago from a cloud
of dust and hot gases. Initially, it was very hot.
• With time, the hot gases gradually formed clouds. There
were continuous rains that cooled the outer surface.

9. THE STRUCTURE OF THE EARTH
• So, the surface became hard on cooling. Water appeared
on the surface in liquid form.
• The gases formed the atmosphere. Slowly, the conditions
became suitable for life to take form.
• The earth is made up of three layers—crust, mantle and
core.

10. • The outermost layer of the earth is called the crust. It
is made up of rocks, mainly granite and
basalt.
• The layer below the crust is called mantle. It is hot and
made up of a thick layer of rocks rich in minerals such as
iron and magnesium.
• The innermost layer of the earth is very hot and it is in
a molten state. It is known as the core and is made up
of dense minerals, mainly iron and nickel.

12. The molten material present in the core is known as
lava or magma. It gushes out with great force from
cone-shaped mountains which are known as volcanoes.
The hole from where the lava comes out is known as
the crater.