The document discusses landforms created by internal and external forces on Earth. Internal forces like plate tectonics cause volcanoes and earthquakes and form mountains over long periods. The theory of plate tectonics explains how continents split apart from a supercontinent and drifted to their current positions. Most volcanoes are located on the Ring of Fire around the Pacific Ocean where tectonic plates are subducting under each other.

1. Which natural landforms can you spot in the image given above?
Are all the landforms of the Earth similar?
How do the natural forces and landforms impart a dynamic character to the Earth?

2. EARTHS MOVEMENTS AND
CHANGING LANDFORMS
LO:
1. To classify the movements of the earth.
2. To explain why and how earthquakes occur.
3. To explain how volcanoes are formed.

3. ENDOGENIC AND EXOGENIC FORCES
The movements of the earth can broadly be divided into two on the
basis of forces that cause them .
The internal or endogenic forces originate within the Earth's crust create
• slow Earth movements that form continents, ocean beds, mountains, plateaus and
plains.
• sudden Earth movements such as volcanic emptions, earthquakes and landslides.
• The external or exogenic forces which originate outside the Earth 's crust cause
changes on the surface of the Ea1th. For example, through erosion and
deposition by natural agents such as wind, water, and so on.

4. FORMATION OF LANDFORMS BY
INTERNAL PROCESSES
•According to the Theory of Plate Tectonics, the Earth's lithosphere is divided
into several Iarge and small irregularly shaped plates, called lithospheric
or tectonic plates. It is believed that these plates are 'floating' on the molten mantle or
the asthenosphere and a.re in a state of constant motion. These movements
take place mainly due to the heat generated within the interior of the Earth.
The movement of the lithospheric plates causes changes to the surface of the Earth.

5. Video:
https://youtu.be/7h6tPalC1sU

6. Can You Remember What’s Under Your Feet?
Mark the layers of the earth

7. HOW WERE THE SEVEN CONTINENTS FORMED? CAN YOU EXPLAIN IT?

8. THE THEORY OF CONTINENTAL DRIFT
Today we observe millions of geological changes on the face of the
earth. To explain the current position of the continents and the oceans,
several scientists put forth different theories.
The foremost attempt was made by Alfred Wegener in 1912. He was a
German meteorologist. He tried to explain the present division of the
continents and the oceans. According to his theory, a supercontinent
called Pangaea broke into different continents 200 million years ago
and the continents drifted to their present locations. This theory is
called the Continental Drift theory.

9. THE THEORY OF CONTINENTAL DRIFT
Movements of the plates occur due to the various
forces acting upon it. Two broad categories of these
forces are the endogenic and exogenic.
Endogenic forces act in the interior of the earth.
Exogenic forces work on the surface of the Earth.
Endogenic forces produce slow as well as sudden
movements like earthquakes and volcanoes which
cause mass destructions over the surface of the
earth. Horizontal and vertical movements are also
produced by them, which result in variety of relief
features like mountain building.
Erosional and depositional works are done by
exogenic forces like rivers, wind, glaciers and sea
waves.

10. EARTH’S MOVEMENTS

11. What do you see?

12. The Earth’s Plates
The Earth’s plates are always
moving. They move so slowly
that we usually can’t feel it.
The edges of plates are called
faults. Faults can rub together,
push toward each other, or pull
away from each other.
Have a look at the Earth’s plates.
What do you notice about where
New Zealand is?

13. The tectonic plates are constantly
Rubbing together Moving towards each
other
Moving away from each
other
This kind of movement causes earthquakes.

14. An earthquake is the sudden and sometimes violent shaking of the
Earth’s crust. It can have devastating effects on the land and areas on
the surface as a result of the shock waves from the energy built up
underground.
What is an Earthquake?

15. The place of origin of an
earthquake is called FOCUS.
The point on the earth’s surface
which is vertically above the
focus is called the EPICENTRE.
The vibrations of an earthquake
spread out in concentric waves
from the focus. These
vibrations are called seismic
waves.
The effect or intensity of an
earthquake is most at the
epicenter. The surface of the
earth can shake due to the
movements of the lithosphere
plates, volcanic eruptions or
even bomb explosion.

16. How Are Volcanoes Made?
Pressure builds up
inside the Earth.
This then affects the
Earth’s crust, so that
magma can
sometimes erupt
through it.
The lava and ash that
has erupted through
the crust build up to
form the classic volcano
cone shape over time.
This process is happening
all the time!

17. Watch the video about volcanoes.
• https://youtu.be/lAmqsMQG3RM

18. What’s It All Called?
magma chamber
eruption cloud
crater
conduit/main vent
Secondary vent
lava

19. Mark the parts of a volcano.

20. Types of Volcanoes
active
A volcano that erupts frequently and throws out ashes, gases,
lava and rocks.- Etna and Stromboli in Italy, Kilauea in Hawaii
dormant
A volcano that has erupted and is quiet now. They don’t show signs of
erupting in the near future, but may erupt again. Vesuvius in Italy,
extinct
A volcano that hasn’t erupted in the last 10 000 years, and isn’t
expected to erupt again. Mount Kilimanjaro in Tanzania.

21. Where Are Most Volcanoes Located? Distribution of volcanoes
The circum – pacific Belt: It encircles the pacific ocean. It is also known as
Pacific “.Ring of fire”
Most volcanoes are
located in the red area,
which is named “Ring
of Fire”.
Most of the volcanoes are located
in the Andes of S.America and th
Rockies of N.America
Why do you think it is
called that?

22. A second belt of volcanoes is found along the
Mediterranean Sea.
• It is called the Mid World Mountain Belt.
• It mostly has dormant and extinct volcanoes.