LN.3 – EARTH MOVEMENTS & MAJOR LANDFORMS
OUTCOMES OF FOCUSED LEARNING:
 Folding
 Faulting
 Volcanoes
 Earthquakes
KEY TERMS:
1. Plates: division of crust into several large slabs of rocks
2. Magma: molten material inside the earth
3. Fissure: crack or gap through which magma oozes out
4. Richter Scale: the scale used for measuring the earthquake
5. Seismograph: Instrument used for the measurement of the quakes
6. Seismologists: People who study earthquakes
7. Seismology: Study of earthquakes
4. ANSWER THE FOLLOWING QUESTIONS IN ONE OR TWO
SENTENCES:
a. What do you understand by plate tectonics?
The study of the movements of the earth’s plates and the
associated phenomena is plate tectonics.
b. What is folding?
Folding is the wave-like upliftment of sedimentary rocks due to
horizontal forces from two opposite sides.
c. What is a rift valley?
A rift valley is a sunken portion of land between two block
mountains. Examples: Deccan plateau
d. What causes the formation of block mountain?
Block mountains are formed when the land between the two
faults or cracks is uplifted by internal forces. Examples: The
Vindhya, The Satpura
e. What do you understand by the focus of an earthquake?
The point where the earthquake waves originate inside the
earth is called the focus of the earthquake.
5. ANSWER THE FOLLOWING QUESTIONS IN FOUR OR FIVE
SENTENCES:
a. What is a fold mountain?
FOLD MOUNTAIN:
 A fold mountain is formed due to folding or wave-like upliftment
of sedimentary rocks due to horizontal forces from two opposite
sides.
 This happen when a part of the crust is pushed against another.
 Examples: The Himalayas, The Aravallis.
b. Explain the formation of a block mountain.
FORMATION OF A BLOCK MOUNTAIN:
 Due to tension vertical faults or cracks are created along the lines
of weakness in the crust.
 Sometimes the land between the cracks is uplifted by internal
forces, forming a block mountain or horst.
 Examples: The Vindhya, The Satpura
c. How is a rift valley formed?
FORMATION OF A RIFT VALLEY:
 A rift valley is created when a part of the crust between two faults
sings down.
 The land on either side of the valley remains standing as block
mountains.
 Examples: The Himalayas, The Aravallis.
d. Describe a volcano with a suitable diagram?
VOLCANO:
Volcanoes are openings in the earth’s crust through which molten
minerals, ash and hot gases are thrown out.
a. Magma Chamber: A large underground pool of molten rock below
the crust
b. Vent: The opening through which the magma comes onto the surface
c. Crater: A bowl-shaped depression at the mouth of the volcano
d. Lava flow: A mass of flowing or molten lava
e. What is an earthquake? What causes it?
EARTHQUAKE:
 Earthquakes are vibrations or tremors felt on the surface of the
earth.
 The tremors are caused due to disturbances beneath the crust.
 These disturbances could either be due to plates colliding or
rubbing against each other or due to volcanic eruptions.
 The point where the earthquake waves originate inside the earth
is called the focus of the earthquake.
 The tremors or vibrations produced during an earthquake are also
called seismic waves.