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CHAPTER-3
GEOGRAPHY
EARTH’S MOVEMENTS AND MAJOR LANDFORMS
SUMMARY
•Exogenic forces are those that act on the earth’s surface, such as wind, water,
ice, temperature conditions, etc. and modify the face of the Earth.
• Endogenic forces are those which act beneath the Earth’s surface.
•The Earth’s crust is divided in to seven main lithospheric plates.
•Circular heat currents are generated in the Earth’s mantle which cause
movement in the plates.
•The movement of the Earth’s lithospheric plates is termed as tectonic
movements.
•Tectonic movements are divided in to horizontal movements and vertical
movements.
•Horizontal movements give rise to tensional forces which cause faulting in
the Earth’s surface and create rift valleys and fold mountains.
•Vertical movements are caused by forces that uplift the Earth’s crust or cause
it subsidence.
•When blocks of rocks get dislocated from a plane a fault or a deep crack
occurs.
•Convergent plate movements are a result of compressional forces.
•Divergent plate movements are a result of tensional forces.
•The point where the earthquake originates is called the focus.
•The point on the surface that is vertically above the focus is called epicenter.
•The Richter scale measures the strength or intensity of the shock waves
produced by an earthquake.
• A volcano is an opening or a vent in the surface of a planet through which
molten magma, ash, and gases come out from below the surface.